1,095 results on '"D. Peters"'
Search Results
2. A Canadian River Ice Database from the National Hydrometric Program Archives
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L. de Rham, Y. Dibike, S. Beltaos, D. Peters, B. Bonsal, and T. Prowse
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Environmental sciences ,GE1-350 ,Geology ,QE1-996.5 - Abstract
River ice, like open-water conditions, is an integral component of the cold-climate hydrological cycle. The annual succession of river ice formation, growth, decay and clearance can include low flows and ice jams, as well as midwinter and spring break-up events. Reports and associated data of river ice occurrence are often limited to single locations or regional assessments, are season-specific, and use readily available data. Within Canada, the National Hydrometric Program (NHP) operates a network of gauging stations with water level as the primary measured variable to derive discharge. In the late 1990s, the Water Science and Technology Directorate of Environment and Climate Change Canada initiated a long-term effort to compile, archive and extract river-ice-related information from NHP hydrometric records. This data article describes the original research data set produced by this near 20-year effort: the Canadian River Ice Database (CRID). The CRID holds almost 73 000 recorded variables from a subset of 196 NHP stations throughout Canada that were in operation within the period 1894 to 2015. Over 100 000 paper and digital files were reviewed, representing 10 378 station years of active operation. The task of compiling this database involved manual extraction and input of more than 460 000 data entries on water level, discharge, ice thickness, date, time and data quality rating. Guidelines on the data extraction, rating procedure and challenges are provided. At each location, time series of up to 15 variables specific to the occurrence of freeze-up and winter-low events, midwinter break-up, ice thickness, spring break-up, and maximum open-water level were compiled. This database follows up on several earlier efforts to compile information on river ice, which are summarized herein, and expands the scope and detail for use in Canadian river ice research and applications. Following the Government of Canada Open Data initiative, this original river ice data set is available at https://doi.org/10.18164/c21e1852-ba8e-44af-bc13-48eeedfcf2f4 (de Rham et al., 2020).
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- 2020
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3. Classical and quantum anisotropic Heisenberg antiferromagnets
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W. Selke, G. Bannasch, M. Holtschneider, I.P. McCulloch, D. Peters, and S. Wessel
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Heisenberg antiferromagnets ,Monte Carlo simulation ,DMRG ,biconical phase ,supersolid phase ,multicritical point ,Physics ,QC1-999 - Abstract
We study classical and quantum Heisenberg antiferromagnets with exchange anisotropy of XXZ-type and crystal field single-ion terms of quadratic and quartic form in a field. The magnets display a variety of phases, including the spin-flop (or, in the quantum case, spin-liquid) and biconical (corresponding, in the quantum lattice gas description, to supersolid) phases. Applying ground-state considerations, Monte Carlo and density matrix renormalization group methods, the impact of quantum effects and lattice dimension is analysed. Interesting critical and multicritical behaviour may occur at quantum and thermal phase transitions.
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- 2009
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4. Gender sensitivity in health service provision in Afghanistan from 2012-2013
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J. Gupta and D. Peters
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Infectious and parasitic diseases ,RC109-216 ,Public aspects of medicine ,RA1-1270 - Published
- 2015
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5. Inertia gravity waves in the upper troposphere during the MaCWAVE winter campaign – Part II: Radar investigations and modelling studies
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A. Serafimovich, Ch. Zülicke, P. Hoffmann, D. Peters, P. Dalin, and W. Singer
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Science ,Physics ,QC1-999 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
We present an experimental and modelling study of a strong gravity wave event in the upper troposphere/lower stratosphere near the Scandinavian mountain ridge. Continuous VHF radar measurements during the MaCWAVE rocket and ground-based measurement campaign were performed at the Norwegian Andoya Rocket Range (ARR) near Andenes (69.3° N, 16° E) in January 2003. Detailed gravity wave investigations based on PSU/NCAR Fifth-Generation Mesoscale Model (MM5) data have been used for comparison with experimentally obtained results. The model data show the presence of a mountain wave and of an inertia gravity wave generated by a jet streak near the tropopause region. Temporal and spatial dependencies of jet induced inertia gravity waves with dominant observed periods of about 13 h and vertical wavelengths of ~4.5–5 km are investigated with wavelet transform applied on radar measurements and model data. The jet induced wave packet is observed to move upstream and downward in the upper troposphere. The model data agree with the experimentally obtained results fairly well. Possible reasons for the observed differences, e.g. in the time of maximum of the wave activity, are discussed. Finally, the vertical fluxes of horizontal momentum are estimated with different methods and provide similar amplitudes. We found indications that the derived positive vertical flux of the horizontal momentum corresponds to the obtained parameters of the jet-induced inertia gravity wave, but only at the periods and heights of the strongest wave activity.
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- 2006
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6. Investigation of inertia-gravity waves in the upper troposphere/lower stratosphere over Northern Germany observed with collocated VHF/UHF radars
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A. Serafimovich, P. Hoffmann, D. Peters, and V. Lehmann
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Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
A case study to investigate the properties of inertia-gravity waves in the upper troposphere/lower stratosphere has been carried out over Northern Germany during the occurrence of an upper tropospheric jet in connection with a poleward Rossby wave breaking event from 17-19 December 1999. The investigations are based on the evaluation of continuous radar measurements with the OSWIN VHF radar at Kühlungsborn (54.1 N, 11.8 E) and the 482 MHz UHF wind profiler at Lindenberg (52.2 N, 14.1 E). Both radars are separated by about 265 km. Based on wavelet transformations of both data sets, the dominant vertical wavelengths of about 2-4 km for fixed times as well as the dominant observed periods of about 11 h and weaker oscillations with periods of 6 h for the altitude range between 5 and 8 km are comparable. Gravity wave parameters have been estimated at both locations separately and by a complex cross-spectral analysis of the data of both radars. The results show the appearance of dominating inertia-gravity waves with characteristic horizontal wavelengths of 300 km moving in the opposite direction than the mean background wind and a secondary less pronounced wave with a horizontal wavelength in the order of about 200 km moving with the wind. Temporal and spatial differences of the observed waves are discussed.
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- 2005
7. Modelling the wintertime response to upper tropospheric and lower stratospheric ozone anomalies over the North Atlantic and Europe
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I. Kirchner and D. Peters
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Science ,Physics ,QC1-999 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
During boreal winter months, mean longitude-dependent ozone changes in the upper troposphere and lower stratosphere are mainly caused by different ozone transport by planetary waves. The response to radiative perturbation induced by these ozone changes near the tropopause on the circulation is unclear. This response is investigated with the ECHAM4 general circulation model in a sensitivity study. In the simulation two different mean January realizations of the ozone field are implemented in ECHAM4. Both ozone fields are estimated on the basis of the observed mean January planetary wave structure of the 1980s. The first field represents a 14-year average (reference, 1979–1992) and the second one represents the mean ozone field change (anomaly, 1988–92) in boreal extra-tropics during the end of the 1980s. The model runs were carried out pairwise, with identical initial conditions for both ozone fields. Five statistically independent experiments were performed, forced with the observed sea surface temperatures for the period 1988 to 1992. The results support the hypothesis that the zonally asymmetric ozone changes of the 80s triggered a systematic alteration of the circulation over the North Atlantic – European region. It is suggested that this feedback process is important for the understanding of the decadal coupling between troposphere and stratosphere, as well as between subtropics and extra-tropics in winter.Key words. Meteorology and atmospheric dynamics (general circulation; radiative processes; synoptic-scale meteorology)
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- 2003
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8. The Lagrangian structure of ozone mini-holes and potential vorticity anomalies in the Northern Hemisphere
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P. M. James and D. Peters
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Science ,Physics ,QC1-999 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
An ozone mini-hole is a synoptic-scale area of strongly reduced column total ozone, which undergoes a growth-decay cycle in association with baroclinic weather systems. The tracks of mini-hole events recorded during the TOMS observation period over the Northern Hemisphere provide a database for building anomaly fields of various meteorological parameters, following each mini-hole center in a Lagrangian sense. The resulting fields provide, for the first time, a complete mean Lagrangian picture of the three-dimensional structure of typical ozone mini-holes in the Northern Hemisphere. Mini-holes are shown to be associated with anomalous warm anticyclonic flow in the upper troposphere and cold cyclonic anomalies in the middle stratosphere. Ascending air columns occur upstream and descent downstream of the mini-hole centers. Band-pass filtering is used to reveal the transient synoptic nature of mini-holes embedded within larger scale circulation anomalies. Significant correlations between ozone and Ertel’s potential vorticity on isentropes (IPV) both near the tropopause and in the middle stratosphere are shown and then utilized by reconstructing the Lagrangian analysis to follow local IPV anomalies instead of ozone minima. By using IPV as a proxy for ozone, the geopotential anomaly dipolar structure in the vertical characteristic of mini-holes is shown to result from a superposition of two largely independent dynamical components, stratospheric and tropospheric, typically operating on different time scales. Hence, ozone mini-holes may be viewed primarily as phenomena of coincidence.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; synoptic-scale meteorology)
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- 2002
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9. Very low zonally asymmetric ozone values in March 1997 above the North Atlantic-European region, induced by dynamic processes
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G. Entzian and D. Peters
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Science ,Physics ,QC1-999 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
The total ozone distribution in March 1997 showed very low values in the North Atlantic-European region, even lower than in the years before. A spatial pattern correlation between the zonally asymmetric part of total ozone and that of the 300 hPa surface geopotential of the Northern Hemisphere was applied to examine the spatial structure of the low ozone values and its dynamic dependence. A trend analysis in the North Atlantic-European region was carried out to determine to what extent the low March 1997 ozone values are related to the decadal change of meteorological parameters in the lower stratosphere, observed since the 1980s, in comparison to the interannual variability. The conclusion is that the very low ozone values above the North Atlantic-European region in March 1997 were mainly induced by dynamic processes, namely their decadal change as well as their interannual variability.Key words. Meteorology and atmospheric dynamics (climatology; middle atmosphere dynamics)
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- 1999
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10. January ozone anomaly over the North Atlantic-European region: Longitude-dependent decadal change in total ozone during 1979-1992
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D. Peters and G. Entzian
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total ozone ,geopotential ,tropopause ,ozone anomaly ,gesamtozon ,geopotentiell ,ozonanomalie ,Meteorology. Climatology ,QC851-999 - Abstract
A large decrease in total ozone of up to more than 4 DU/yr occurred over Europe during January 1979-1992. This value is almost twice that of the zonal mean. A strong change of geopotential height of more than 2 dam/yr also existed in the tropopause region during the same period in the same area. It is shown that the anomaly (differences from the zonal mean) of total ozone and geopotential height of 300 hPa are significantly negative correlated in space and time. This strongly suggests that the ozone anomaly change is essentially caused by changes in those processes which determine the dynamics of the tropopause region.
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- 1996
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11. Assimilation of Remotely Sensed Leaf Area Index Enhances the Estimation of Anthropogenic Irrigation Water Use
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Wanshu Nie, Sujay V. Kumar, Christa D. Peters‐Lidard, Benjamin F. Zaitchik, Kristi R. Arsenault, Rajat Bindlish, and Pang‐Wei Liu
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- 2022
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12. Human CD4+CD25+CD226- Tregs Demonstrate Increased Purity, Lineage Stability, and Suppressive Capacity Versus CD4+CD25+CD127lo/- Tregs for Adoptive Cell Therapy
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Matthew E. Brown, Leeana D. Peters, Seif R. Hanbali, Juan M. Arnoletti, Lindsey K. Sachs, Kayla Q. Nguyen, Emma B. Carpenter, Howard R. Seay, Christopher A. Fuhrman, Amanda L. Posgai, Melanie R. Shapiro, and Todd M. Brusko
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CD226 ,Treg ,lineage stability ,suppressive function ,autoimmune disease ,adoptive cell therapy ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Regulatory T cell (Treg) adoptive cell therapy (ACT) represents an emerging strategy for restoring immune tolerance in autoimmune diseases. Tregs are commonly purified using a CD4+CD25+CD127lo/- gating strategy, which yields a mixed population: 1) cells expressing the transcription factors, FOXP3 and Helios, that canonically define lineage stable thymic Tregs and 2) unstable FOXP3+Helios- Tregs. Our prior work identified the autoimmune disease risk-associated locus and costimulatory molecule, CD226, as being highly expressed not only on effector T cells but also, interferon-γ (IFN-γ) producing peripheral Tregs (pTreg). Thus, we sought to determine whether isolating Tregs with a CD4+CD25+CD226- strategy yields a population with increased purity and suppressive capacity relative to CD4+CD25+CD127lo/- cells. After 14d of culture, expanded CD4+CD25+CD226- cells displayed a decreased proportion of pTregs relative to CD4+CD25+CD127lo/- cells, as measured by FOXP3+Helios- expression and the epigenetic signature at the FOXP3 Treg-specific demethylated region (TSDR). Furthermore, CD226- Tregs exhibited decreased production of the effector cytokines, IFN-γ, TNF, and IL-17A, along with increased expression of the immunoregulatory cytokine, TGF-β1. Lastly, CD226- Tregs demonstrated increased in vitro suppressive capacity as compared to their CD127lo/- counterparts. These data suggest that the exclusion of CD226-expressing cells during Treg sorting yields a population with increased purity, lineage stability, and suppressive capabilities, which may benefit Treg ACT for the treatment of autoimmune diseases.
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- 2022
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13. Towards Effective Drought Monitoring in the Middle East and North Africa (Mena) Region: Implications From Assimilating Leaf Area Index and Soil Moisture Into the Noah-Mp Land Surface Model for Morocco
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Wanshu Nie, Sujay V. Kumar, Kristi R. Arsenault, Christa D. Peters-Lidard, Iliana E. Mladenova, Karim Bergaoui, Abheera Hazra, Benjamin F. Zaitchik, Sarith P. Mahanama, Rachael McDonnell, David M. Mocko, and Mahdi Navari
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Earth Resources and Remote Sensing - Abstract
The Middle East and North Africa (MENA) region has experienced more frequent and severe drought events in recent decades, leading to increasingly pressing concerns over already strained food and water security. An effective drought monitoring and early warning system is thus critical to support risk mitigation and management by countries in the region. Here we investigate the potential for assimilation of leaf area index (LAI) and soil moisture observations to improve the representation of the overall hydrological and carbon cycles and drought by an advanced land surface model. The results reveal that assimilating soil moisture does not meaningfully improve model representation of the hydrological and biospheric processes for this region, but instead it degrades the simulation of the interannual variation in evapotranspiration (ET) and carbon fluxes, mainly due to model weaknesses in representing prognostic phenology. However, assimilating LAI leads to greater improvement, especially for transpiration and carbon fluxes, by constraining the timing of simulated vegetation growth response to evolving climate conditions. LAI assimilation also helps to correct for the erroneous interaction between the prognostic phenology and irrigation during summertime, effectively reducing a large positive bias in ET and carbon fluxes. Independently assimilating LAI or soil moisture alters the categorization of drought, with the differences being greater for more severe drought categories. We highlight the vegetation representation in response to changing land use and hydroclimate as one of the key processes to be captured for building a successful drought early warning system for the MENA region.
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- 2022
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14. Daily Precipitation Frequency Distributions Impacts on Land-Surface Simulations of CONUS
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Daniel P Sarmiento, Kimberly Slinski, Amy McNally, Jossy P Jacob, Chris Funk, Pete Peterson, and Christa D Peters-lidard
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Meteorology And Climatology - Abstract
Many precipitation-driven data products from land data assimilation systems support assessments of droughts, floods, and other societally-relevant land-surface processes.The accumulated precipitation used as input to these products has a significant impacton water budgets; however, the effects of daily distribution of precipitation on theseproducts are not well known. A comparison of the Integrated Multi-satellite Retrievalsfor GPM (IMERG) and Climate Hazards Group InfraRed Precipitation with Stationsversion 2 (CHIRPS2) rainfall products over the continentalUnited States (CONUS) wasperformed to quantify the impacts of the daily distributionof precipitation on biases anderrors in soil moisture, runoff, and evapotranspiration (ET). Since the total accumulatedprecipitation between the IMERG and CHIRPS product differed, a third precipitationproduct, CHIRPS-to-IMERG (CHtoIM), was produced that usedCHIRPS2 accumulatedprecipitation totals and the daily precipitation frequency distribution of IMERG. Thisnew product supported a controlled analysis of the impact ofprecipitation frequencydistribution on simulated hydrological fields. The CHtoIM had higher occurrences ofprecipitation in the 0–5 mm day−1range, with a lower occurrence of dry days, whichdecreased soil moisture and surface runoff in the land-surface model. The surface soillayer had a tendency to reach saturation more often in the CHIRPS2 simulations, wherethe number of moderate to heavy precipitation days (>5mm day−1) was increased. Usingthe blended CHtoIM product as input reduced errors in surface soil moisture by 5–15%when compared to Soil Moisture Active/Passive (SMAP) data.Similarly, ET errors werealso slightly decreased (∼2%) when compared to SSEBop data. Moderate changes indaily precipitation distributions had a quantifiable impact on soil moisture, runoff, andET. These changes usually improved the model when compared to other modeled andobservational datasets, but the magnitude of the improvements varied by region andtime of year.
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- 2021
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15. The Safety of Foot and Ankle Surgical Procedures at an Ambulatory Surgery Center
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Wesley D. Peters BS, Peter J. Adamson MD, Cory Janney MD, and Vinod K. Panchbhavi MD
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Orthopedic surgery ,RD701-811 - Abstract
Category: Ankle; Bunion; Hindfoot; Lesser Toes; Midfoot/Forefoot Introduction/Purpose: There is a growing trend to perform surgical procedures at freestanding ambulatory surgical centers. No literature exists evaluating the rate of adverse events and overall safety of foot and ankle outpatient surgeries at a freestanding ambulatory surgery center (ASC). Methods: A retrospective review of all foot and ankle cases performed over a two year period at a single freestanding ASC. A total of 313 cases were performed. Adverse events are state-reported events that cause harm or lead to additional treatment. Using state-reported adverse events criteria and previous literature from hand and upper-extremity cases, we categorized our adverse events into seven categories: 1) infection requiring intravenous abx or return to the operating room, 2) postoperative transfer to a hospital, 3) wrong-site surgery, 4) retention of a foreign object, 5) postoperative symptomatic thromboembolism (DVT), 6) medication error, and 7) bleeding complications. Results: The overall rate of adverse events was 3.5% with 11 events identified over the two year period. There were a total of 10 infections and 1 symptomatic DVT. There were no cases that resulted in transfer to a hospital, hospital admission after discharge, medication error, bleeding complications, wrong-site procedures, or retained foreign bodies. Conclusion: Outpatient foot and ankle procedures are not without complications, but the overall rate of complications postoperatively is farly low (3.5%). Overall, foot and ankle surgeries can be performed safely in an outpatient setting at an ASC.
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- 2020
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16. Advances in Land Surface Models and Indicators for Drought Monitoring and Prediction
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Christa D Peters-lidard, David M Mocko, Lu Su, Dennis Lettenmaier, Pierre Gentine, and Michael Barlage
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Meteorology And Climatology - Abstract
Millions of people across the globe are affected by droughts every year, and recent droughts have highlighted the considerable agricultural impacts and economic costs of these events. Monitoring the state of droughts depends on integrating multiple indicators that each capture particular aspects of hydrologic impact and various types and phases of drought. As the capabilities of land surface models and remote sensing have improved, important physical processes such as dynamic, interactive vegetation phenology, groundwater, and snowpack evolution now support a range of drought indicators that better reflect coupled water, energy, and carbon cycle processes. In this work, we discuss these advances, including newer classes of indicators that can be applied to improve the characterization of drought onset, severity, and duration. We utilize a new model-based drought reconstruction to illustrate the role of dynamic phenology and groundwater in drought assessment. Further, through case studies on flash droughts, snow droughts, and drought recovery, we illustrate the potential advantages of advanced model physics and observational capabilities, especially from remote sensing, in characterizing droughts.
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- 2021
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17. Drought Variability over the Conterminous United States for the past century
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Lu Su, QianCao, Mu Xiao, David M.Mocko, Michael Barlage, Dongyue Li, Christa D Peters-lidard, and Dennis P. Lettenmaier
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Meteorology And Climatology - Abstract
We examine the drought variability over the Conterminous United States (CONUS) for 1915-2018 using the Noah-MP land-surface model. We examine different model options on drought reconstruction including optional representation of groundwater and dynamic vegetation phenology. Over our 104-year reconstruction period, we identify 12 great droughts that each covered at least 36% of CONUS and lasted for at least 5 months. The great droughts tend to have smaller areas when groundwater and/or dynamic vegetation are included in the model configuration. We detect a small decreasing trend in dry area coverage over CONUS in all configurations. We identify 45 major droughts in the baseline (with a dry area coverage greater than 23.6% of CONUS) that are, on average, somewhat less severe than great droughts. We find that representation of groundwater tends to increase drought duration for both great and major droughts, primarily by leading to earlier drought onset (some due to short-lived recovery from a previous drought) or later demise (groundwater anomalies lag precipitation anomalies). In contrast, representation of dynamic vegetation tends to shorten major droughts duration, primarily due to earlier drought demise ( closed stoma or dead vegetation reduces ET loss during droughts). On a regional basis, the U.S. Southwest (Southeast) has the longest (shortest) major drought durations. Consistent with earlier work, dry area coverage in all subregions except the Southwest has decreased. The effects of groundwater and dynamic vegetation vary regionally due to differences in groundwater depths (hence connectivity with the surface) and vegetation types.
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- 2021
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18. Assimilation of vegetation conditions improves the representation of drought over agricultural areas
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David M Mocko, Sujay V Kumar, Christa D Peters-Lidard, and Shugong Wang
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Geosciences (General) ,Earth Resources And Remote Sensing - Abstract
This study presents an evaluation of the impact of vegetation conditions on a land-surface model (LSM) simulation of agricultural drought. The Noah-MP LSM is used to simulate water and energy fluxes and states, which are transformed into drought categories using percentiles over the continental U.S. from 1979 to 2017. Leaf Area Index (LAI) observations are assimilated into the dynamic vegetation scheme of Noah-MP. A weekly operational drought monitor (the U.S. Drought Monitor) is used for the evaluation. The results show that LAI assimilation into Noah-MP’s dynamic vegetation scheme improves the model’s ability to represent drought, particularly over cropland areas. LAI assimilation improves the simulation of the drought category, detection of drought conditions, and reduces the instances of drought false alarms. The assimilation of LAI in these locations not only corrects model errors in the simulation of vegetation, but also can help to represent unmodeled physical processes such as irrigation towards improved simulation of agricultural drought.
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- 2021
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19. Multiphase Coexistence in Binary Hard Colloidal Mixtures
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J. Opdam, V. F. D. Peters, H. H. Wensink, R. Tuinier, Physical Chemistry, and ICMS Core
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General Materials Science ,Physical and Theoretical Chemistry - Abstract
A general theoretical framework is proposed to quantify the thermodynamic properties of multicomponent hard colloidal mixtures. This framework is used to predict the phase behavior of mixtures of rods with spheres and rods with plates taking into account (liquid) crystal phases of both components. We demonstrate a rich and complex range of phase behaviors featuring a large variety of different multiphase coexistence regions, including two five-phase coexistence regions for hard rod/sphere mixtures, and even a six-phase equilibrium for hard rod/plate dispersions. The various multiphase coexistences featured in a particular mixture are in line with a recently proposed generalized phase rule and can be tuned through subtle variations of the particle shape and size ratio. Our approach qualitatively accounts for certain multiphase equilibria observed in rod/plate mixtures of clay colloids and will be a useful guide in tuning the phase behavior of shape-disperse mixtures in general.
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- 2023
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20. Assimilation of Vegetation Optical Depth Retrievals from Passive Microwave Radiometry
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Sujay V Kumar, Thomas R Holmes, Rajat Bindlish, Christa D Peters-lidard, Richard de Jeu, and Christa Peters-Lidard
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Earth Resources And Remote Sensing - Abstract
Vegetation optical depth (VOD) retrievals from passive microwave sensors provide analog estimates of above-ground canopy biomass. This study presents the development and analysis of assimilating VOD retrievals from X-, C-, and L-band passive microwave instruments within the Noah-MP land surface model over the Continental U.S. The results from this study demonstrate that the assimilation of VOD retrievals have a significant beneficial impact on the simulation of evapotranspiration and GPP, particularly over the agricultural areas of the U.S. The improvements in the water and carbon fluxes from the assimilation of VOD from X- and C-band sensors are found to be comparable to those obtained from the assimilation of vegetation indices from optical sensors.The study also quantifies the relative and joint impact of assimilating surface soil moisture and VOD from the Soil Moisture Active Passive (SMAP) mission. The utility of soil moisture assimilation for improving ET is more significant over water-limited regions, whereas VOD DA is more impactful over areas where soil moisture is not the primary controlling factor on ET. The results also indicate that the information on moisture and vegetation states from SMAP can be simultaneously exploited through the joint assimilation of surface soil moisture and VOD. Since passive microwave-based VOD retrievals are available in nearly all weather conditions, their use within data assimilation systems offers the ability to extend and improve the utility obtained from the use of optical/infrared based vegetation retrievals
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- 2020
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21. Role of forcing uncertainty and background model error characterization in snow data assimilation
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S. V. Kumar, J. Dong, C. D. Peters-Lidard, D. Mocko, and B. Gómez
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Technology ,Environmental technology. Sanitary engineering ,TD1-1066 ,Geography. Anthropology. Recreation ,Environmental sciences ,GE1-350 - Abstract
Accurate specification of the model error covariances in data assimilation systems is a challenging issue. Ensemble land data assimilation methods rely on stochastic perturbations of input forcing and model prognostic fields for developing representations of input model error covariances. This article examines the limitations of using a single forcing dataset for specifying forcing uncertainty inputs for assimilating snow depth retrievals. Using an idealized data assimilation experiment, the article demonstrates that the use of hybrid forcing input strategies (either through the use of an ensemble of forcing products or through the added use of the forcing climatology) provide a better characterization of the background model error, which leads to improved data assimilation results, especially during the snow accumulation and melt-time periods. The use of hybrid forcing ensembles is then employed for assimilating snow depth retrievals from the AMSR2 instrument over two domains in the continental USA with different snow evolution characteristics. Over a region near the Great Lakes, where the snow evolution tends to be ephemeral, the use of hybrid forcing ensembles provides significant improvements relative to the use of a single forcing dataset. Over the Colorado headwaters characterized by large snow accumulation, the impact of using the forcing ensemble is less prominent and is largely limited to the snow transition time periods. The results of the article demonstrate that improving the background model error through the use of a forcing ensemble enables the assimilation system to better incorporate the observational information.
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- 2017
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22. Age-related no-go P300 amplitudes are moderated by exposure to early-life stress
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Elizabeth R. Paitel, Sierra D. Peters, Michelle Lobermeier, and Raquel A. Lopez
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Aging ,Young Adult ,Neuropsychology and Physiological Psychology ,Adverse Childhood Experiences ,Parietal Lobe ,Physiology (medical) ,General Neuroscience ,Humans ,Electroencephalography ,Event-Related Potentials, P300 ,Article ,Aged - Abstract
Deficits in inhibitory control are common with advancing age and may underlie declines in other complex cognitive functions. The inhibitory P300 event-related potential (ERP) generally decreases in amplitude with age, reflecting deficits in inhibitory performance evaluation and adaptation, with possible generators including precentral and inferior frontal gyri and midcingulate and parietal cortex. Exposure to early-life stress (ELS) is also associated with deficits in inhibitory control, smaller P300 amplitudes, and dysfunction in regions associated with P300 generation. Although biopsychosocial effects of ELS are evident in older adulthood, the influence of ELS on neural processes in later life is unknown. In the current study, 13 young adults and 21 healthy older adults completed a high-accuracy go/no-go task and the Juvenile Victimization Questionnaire (JVQ), an indicator of ELS. Regression analyses revealed significant central-parietal models, with smaller P300 amplitudes predicted by both older age and greater exposure to ELS. Age group*ELS interactions moderated P300 prediction at central and centro-parietal electrodes, such that older age predicted smaller P300 amplitudes only in those with lower to moderate ELS. Amplitudes did not significantly differ by age in those with higher ELS. Post-hoc within-age group correlations showed that greater ELS was associated with smaller P300 amplitudes in young adults. However, greater ELS was modestly associated with larger central amplitudes in older adults, potentially suggestive of anterior age-related compensatory recruitment to maintain high task performance. These findings suggest long-lasting neural implications of ELS that interact with normative neuro-cognitive aging processes, such that ELS may be an important risk factor for age-related cognitive decline.
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- 2022
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23. A genomic data archive from the Network for Pancreatic Organ donors with Diabetes
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Daniel J. Perry, Melanie R. Shapiro, Sonya W. Chamberlain, Irina Kusmartseva, Srikar Chamala, Leandro Balzano-Nogueira, Mingder Yang, Jason O. Brant, Maigan Brusko, MacKenzie D. Williams, Kieran M. McGrail, James McNichols, Leeana D. Peters, Amanda L. Posgai, John S. Kaddis, Clayton E. Mathews, Clive H. Wasserfall, Bobbie-Jo M. Webb-Robertson, Martha Campbell-Thompson, Desmond Schatz, Carmella Evans-Molina, Alberto Pugliese, Patrick Concannon, Mark S. Anderson, Michael S. German, Chester E. Chamberlain, Mark A. Atkinson, and Todd M. Brusko
- Subjects
Statistics and Probability ,Library and Information Sciences ,Statistics, Probability and Uncertainty ,Computer Science Applications ,Education ,Information Systems - Abstract
The Network for Pancreatic Organ donors with Diabetes (nPOD) is the largest biorepository of human pancreata and associated immune organs from donors with type 1 diabetes (T1D), maturity-onset diabetes of the young (MODY), cystic fibrosis-related diabetes (CFRD), type 2 diabetes (T2D), gestational diabetes, islet autoantibody positivity (AAb+), and without diabetes. nPOD recovers, processes, analyzes, and distributes high-quality biospecimens, collected using optimized standard operating procedures, and associated de-identified data/metadata to researchers around the world. Herein describes the release of high-parameter genotyping data from this collection. 372 donors were genotyped using a custom precision medicine single nucleotide polymorphism (SNP) microarray. Data were technically validated using published algorithms to evaluate donor relatedness, ancestry, imputed HLA, and T1D genetic risk score. Additionally, 207 donors were assessed for rare known and novel coding region variants via whole exome sequencing (WES). These data are publicly-available to enable genotype-specific sample requests and the study of novel genotype:phenotype associations, aiding in the mission of nPOD to enhance understanding of diabetes pathogenesis to promote the development of novel therapies.
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- 2023
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24. The co-ordinative practices of temporary organisations
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Linda D Peters and Andrew D Pressey
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- 2016
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25. The Role of Low-Level, Terrain-Induced Jets in Rainfall Variability in Tigris–Euphrates Headwaters
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Amin K. Dezfuli, Benjamin F. Zaitchik, Hamada S. Badr, Jason Evans, and Christa D. Peters-Lidard
- Published
- 2017
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26. Interactive Spreadsheeting: A Learning Strategy and Exercises for Calculative Management Accounting Principles
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Matt D. Peters and Cecilia Chiu
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Accounting ,ComputingMilieux_COMPUTERSANDEDUCATION ,Education - Abstract
This paper provides an active learning strategy with 34 interactive Excel spreadsheets incorporating 8 core calculative principles for use in management accounting courses. Central to this “interactive learning strategy” is how the dynamic formula functionality of Excel enables highly complex calculative exercises to be parsimoniously structured in templates with color-coded instant feedback. Careful design and selection of solution cells focus learning on core concepts of calculative principles. The strategy involves three forms of interactive learning: students interact with the exercises via the instant feedback functionality, students can interact personally with the instructor, and students can collaboratively interact with other students. With the exercises, the learning strategy is easily implementable into in-person and online classes as complements to traditional lecture segments and textbook exercises. It offers a more engaging and more productive learning experience as perceived by students compared to traditional “pen and paper” exercises (for online classes too). Data Availability: Data are available upon request.
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- 2022
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27. Integrated Coherent Tunable Laser (ICTL) With Ultra-Wideband Wavelength Tuning and Sub-100 Hz Lorentzian Linewidth
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Chao Xiang, John E. Bowers, Joel Guo, Minh A. Tran, Christopher D. Morton, Paul A. Morton, Jonathan D. Peters, Michael J. Morton, and Jacob B. Khurgin
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Silicon photonics ,Materials science ,Relative intensity noise ,business.industry ,Reflector (antenna) ,Laser ,Noise (electronics) ,Atomic and Molecular Physics, and Optics ,law.invention ,Laser linewidth ,law ,Phase noise ,Optoelectronics ,business ,Tunable laser - Abstract
This paper describes the design, fabrication, and record performance of a new class of ultra-wideband wavelength tuning, ultra-low noise semiconductor laser, the Integrated Coherent Tunable Laser (ICTL). The ICTL device is designed for, and fabricated in, a CMOS foundry based Silicon Photonics platform, utilizing heterogeneous integration of III-V material to create the integrated gain section of the laser - enabling high-volume mass-market manufacturing at low cost and with high reliability. The ICTL incorporates three or more ultra-low loss micro-ring resonators, with large ring size, in a Sagnac loop reflector geometry, creating exceptional laser reflector performance, plus an extended laser cavity length that enables highly-coherent output; ultra-low linewidth and phase noise. This paper describes record integrated laser performance; 118 nm wavelength tuning, covering S-, C- and L-bands, with Lorentzian linewidth
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- 2022
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28. The Solar Panels Business Case: A Management Accounting Instructional Resource
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Matt D. Peters
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Accounting ,Education - Abstract
This case instructs students through the preparation of a real-world business case with a sustainability theme. The case involves capital expenditure analysis and communication for installing solar panels on roofs of two warehouses in the Super-Savers Supermarkets supply chain. Installing solar panels would save electricity costs from the public grid and save carbon dioxide greenhouse gas emissions. There are insource and outsource scenarios. The business case has three parts: (1) use Excel (including Goal Seek) to prepare a financial model with a discounted cash flow method—to analyze incremental capital expenditures, costs, profit impacts, and carbon dioxide emission savings; (2) prepare a Word report that concisely communicates the financial model and business case; and (3) prepare a PowerPoint presentation that concisely communicates the financial model and business case. A practice financial modeling exercise is included. The case suits undergraduate and graduate management accounting courses.
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- 2022
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29. Phase stability of colloidal spheres mixed with semiflexible supramolecular polymers
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Vincent F. D. Peters, Remco Tuinier, Mark Vis, Physical Chemistry, and ICMS Core
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Materials science ,Polymers ,Supramolecular chemistry ,Biophysical Phenomena ,Biomaterials ,Depletion ,Colloid and Surface Chemistry ,Critical point (thermodynamics) ,Phase (matter) ,Supramolecular ,Colloids ,Semiflexible polymers ,Phase diagram ,Persistence length ,chemistry.chemical_classification ,Quantitative Biology::Biomolecules ,Temperature ,Hard spheres ,Polymer ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Supramolecular polymers ,Condensed Matter::Soft Condensed Matter ,chemistry ,Models, Chemical ,Chemical physics - Abstract
Hypothesis Mixtures of colloids and supramolecular polymers may exhibit stimuli-responsive phase behaviour. However, in theoretical descriptions of such systems, the polymers are commonly described either as flexible chains or as rigid rods, while in experimental systems supramolecular polymers usually fall in between these two limits. We expect the flexibility of the polymers to have a profound effect on the stimuli-responsive phase behaviour. Theory We propose a general approach to predict the phase behaviour of colloidal hard spheres mixed with covalent or supramolecular polymers of arbitrary persistence length using free volume theory and an interpolation between flexible and rigid chains. Findings The binodals are predicted to shift to lower monomer concentrations as the persistence length is increased, making the polymers more efficient depletants. The persistence length is therefore an additional degree of freedom for manipulating the phase behaviour of colloid–polymer mixtures. We show that by manipulating the persistence length of temperature responsive supramolecular polymers, a wide range of phase diagrams with various topologies can be obtained. For example, we find phase diagrams with a critical point but no triple point or displaying two triple points for temperature-sensitive supramolecular polymers mixed with hard spheres.
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- 2022
30. Introducing and Evaluating the Climate Hazards Center IMERG with Stations (CHIMES): Timely Station-Enhanced Integrated Multisatellite Retrievals for Global Precipitation Measurement
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Christa D. Peters-Lidard, Gregory Husak, Alex C. Ruane, Pete Peterson, Chris Funk, Juliet Way-Henthorne, Seth H. Peterson, Austin Sonnier, Carolyn Z. Mutter, Laura Harrison, George J. Huffman, Martin Landsfeld, Will Turner, Frank Davenport, Shraddhanand Shukla, and Diego Pedreros
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Atmospheric Science ,Meteorology ,Environmental science ,Center (algebra and category theory) ,Satellite ,Global Precipitation Measurement - Abstract
As human exposure to hydroclimatic extremes increase and the number of in situ precipitation observations declines, precipitation estimates, such as those provided by the Integrated Multisatellite Retrievals for Global Precipitation Measurement (GPM) (IMERG) mission, provide a critical source of information. Here, we present a new gauge-enhanced dataset [the Climate Hazards Center IMERG with Stations (CHIMES)] designed to support global crop and hydrologic modeling and monitoring. CHIMES enhances the IMERG Late Run product using an updated Climate Hazards Center (CHC) high-resolution climatology (CHPclim) and low-latency rain gauge observations. CHPclim differs from other products because it incorporates long-term averages of satellite precipitation, which increases CHPclim’s fidelity in data-sparse areas with complex terrain. This fidelity translates into performance increases in unbiased IMERGlate data, which we refer to as CHIME. This is augmented with gauge observations to produce CHIMES. The CHC’s curated rain gauge archive contains valuable contributions from many countries. There are two versions of CHIMES: preliminary and final. The final product has more copious and better-curated station data. Every pentad and month, bias-adjusted IMERGlate fields are combined with gauge observations to create pentadal and monthly CHIMESprelim and CHIMESfinal. Comparisons with pentadal, high-quality gridded station data show that IMERGlate performs well (r = 0.75), but has some systematic biases which can be reduced. Monthly cross-validation results indicate that unbiasing increases the variance explained from 50% to 63% and decreases the mean absolute error from 48 to 39 mm month−1. Gauge enhancement then increases the variance explained to 75%, reducing the mean absolute error to 27 mm month−1.
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- 2022
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31. Toward a ground-based and long-term meteorological forcing dataset for South Korea
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Kyungtae Lee, Do Hyuk Kang, Hahn Chul Jung, Gwangha Park, Changwoo Gye, Sujay Kumar, Edward J. Kim, Christa D. Peters-lidard, and EuiHo Hwang
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Atmospheric Science - Abstract
The Modern-Era Retrospective Analysis for Research and Application version 2 (MERRA-2) is a well-established reanalysis dataset and is widely used for driving global-scale hydrological models. However, owing to its relatively coarse spatial resolution (0.5°), the capability of MERRA-2 is repeatedly challenged in regional-scale studies, especially for smaller areas of interest. In addition, the availability of in situ observation data is a pressing issue for generating meteorological forcing. We developed a grid-based high spatial (0.125°) and temporal (hourly) resolution meteorological forcing dataset, which can evaluate hydrological processes in South Korea using state-of-the-art meteorological observations from 1980 to 2020. The forcing dataset was created by combining Automated Synoptic Observing System (ASOS) in situ measurement data from the Korean Meteorological Administration and MERRA-2 reanalysis datasets. Five meteorological variables were provided in the ASOS-MERRA2 (precipitation, air temperature, surface pressure, specific humidity, and wind speed). The study demonstrates that the region-based and high spatial resolution of ASOS-MERRA2 is superior to the existing MERRA-2 with improvements of all five weather variables, for example, from 5.6 to 2.8 mm root mean square error of precipitation. The ASOS-MERRA2 was more capable of reducing the biases and root mean squared error by improving the coefficient of determination compared with MERRA-2 for all five variables. The newly developed ASOS-MERRA2 provides an opportunity to drive land surface models to evaluate the hydroclimatic conditions in South Korea.
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- 2023
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32. Characterization of leaf surface phenotypes based on light interaction
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Reisha D. Peters and Scott D. Noble
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Genetics ,Plant Science ,Biotechnology - Abstract
Background Leaf surface phenotypes can indicate plant health and relate to a plant’s adaptations to environmental stresses. Identifying these phenotypes using non-invasive techniques can assist in high-throughput phenotyping and can improve decision making in plant breeding. Identification of these surface phenotypes can also assist in stress identification. Incorporating surface phenotypes into leaf optical modelling can lead to improved biochemical parameter retrieval and species identification. Results In this paper, leaf surface phenotypes are characterized for 349 leaf samples based on polarized light reflectance measured at Brewster’s Angle, and microscopic observation. Four main leaf surface phenotypes (glossy wax, glaucous wax, high trichome density, and glabrous) were identified for the leaf samples. The microscopic and visual observations of the phenotypes were used as ground truth for comparison with the spectral classification. In addition to surface classification, the microscope images were used to assess cell size, shape, and cell cap aspect ratios; these surface attributes were not found to correlate significantly with spectral measurements obtained in this study. Using a quadratic discriminant analysis function, a series of 10,000 classifications were run with the data randomly split between training and testing datasets, with 150 and 199 samples, respectively. The average correct classification rate was 72.9% with a worst-case classification of 60.3%. Conclusions Leaf surface phenotypes were successfully correlated with spectral measurements that can be obtained remotely. Remote identification of these surface phenotypes will improve leaf optical modelling and biochemical parameter estimations. Phenotyping of leaf surfaces can inform plant breeding decisions and assist with plant health monitoring.
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- 2023
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33. NCA-LDAS: Overview and Analysis of Hydrologic Trends for the National Climate Assessment
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Michael F. Jasinski, Jordan S. Borak, Sujay V. Kumar, David M. Mocko, Christa D. Peters-Lidard, Matthew Rodell, Hualan Rui, Hiroko K. Beaudoing, Bruce E. Vollmer, Kristi R. Arsenault, Bailing Li, John D. Bolten, and Natthachet Tangdamrongsub
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Earth Resources And Remote Sensing ,Geosciences (General) - Abstract
Terrestrial hydrologic trends over the conterminous United States are estimated for 1980–2015 using the National Climate Assessment Land Data Assimilation System (NCA-LDAS) reanalysis. NCA-LDAS employs the uncoupled Noah version 3.3 land surface model at 0.125° 3 0.125° forced with NLDAS-2 meteorology, rescaled Climate Prediction Center precipitation, and assimilated satellite-based soil moisture, snow depth, and irrigation products. Mean annual trends are reported using the nonparametric Mann–Kendall test at p < 0.1 significance. Results illustrate the interrelationship between regional gradients in forcing trends and trends in other land energy and water stores and fluxes. Mean precipitation trends range from +3 to +9 mm/yr in the upper Great Plains and Northeast to -1 to -9 mm/yr in the West and South, net radiation flux trends range from +0.05 to +0.20 W/sq. m yr in the East to -0.05 to -0.20 W/sq. m yr in the West, and U.S.-wide temperature trends average about +0.03K/yr. Trends in soil moisture, snow cover, latent and sensible heat fluxes, and runoff are consistent with forcings, contributing to increasing evaporative fraction trends from west to east. Evaluation of NCA-LDAS trends compared to independent data indicates mixed results. The RMSE of U.S.-wide trends in number of snow cover days improved from 3.13 to 2.89 days/yr while trend detection increased 11%. Trends in latent heat flux were hardly affected, with RMSE decreasing only from 0.17 to 0.16 W/sq. m yr, while trend detection increased 2%. NCA-LDAS runoff trends degraded significantly from 2.6 to 16.1 mm/yr while trend detection was unaffected. Analysis also indicated that NCA-LDAS exhibits relatively more skill in low precipitation station density areas, suggesting there are limits to the effectiveness of satellite data assimilation in densely gauged regions. Overall, NCA-LDAS demonstrates capability for quantifying physically consistent, U.S. hydrologic climate trends over the satellite era.
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- 2019
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34. Assimilation of Remotely Sensed Leaf Area Index into the Noah-MP Land Surface Model: Impacts on Water and Carbon Fluxes and States over the Continental U.S.
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Sujay V Kumar, David M Mocko, Shugong Wang, Christa D Peters-Lidard, and Jordan S Borak
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Earth Resources And Remote Sensing - Abstract
Accurate representation of vegetation states is required for the modeling of terrestrial water-energy-carbon exchanges and the characterization of the impacts of natural and anthropogenic vegetation changes on the land surface. This study presents a comprehensive evaluation of the impact of assimilating remote sensing-based Leaf Area Index (LAI) retrievals over the Continental U.S. in the Noah-MP land surface model, during a time period of 2000 to 2017. The results demonstrate that the assimilation has a beneficial impact on the simulation of key water budget terms such as soil moisture, evapotranspiration, snow depth, terrestrial water storage and streamflow, when compared with a large suite of reference datasets. In addition, the assimilation of LAI is also found to improve the carbon fluxes of Gross Primary Production (GPP) and Net Ecosystem Exchange (NEE). Most prominent improvements in the water and carbon variables are observed over the agricultural areas of the U.S., where assimilation improves the representation of vegetation seasonality impacted by cropping schedules. The systematic, added improvements from assimilation in a configuration that employs high quality boundary conditions highlight the significant utility of LAI data assimilation in capturing the impacts of vegetation changes.
- Published
- 2019
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35. Hydrologic and Agricultural Earth Observations and Modeling for the Water-Food Nexus
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Amy McNally, Sean Mccartney, Alex C. Ruane, Iliana Mladenova, Alyssa Kathleen Whitcraft, Inbal Becker-Reshef, John D. Bolten, Christa D Peters-lidard, Cynthia E Rosenzweig, and Stephanie Schollaert Uz
- Subjects
Earth Resources And Remote Sensing - Abstract
In a globalizing and rapidly-developing world, reliable, sustainable access to water and food are inextricably linked to each other and basic human rights. Achieving security and sustainability in both requires recognition of these linkages, as well as continued innovations in both science and policy. We present case studies of how Earth observations are being used in applications at the nexus of water and food security: crop monitoring in support of G20 global market assessments, water stress early warning for USAID, soil moisture monitoring for USDA's Foreign Agricultural Service, and identifying food security vulnerabilities for climate change assessments for the UN and the UK international development agency. These case studies demonstrate that Earth observations are essential for providing the data and scalability to monitor relevant indicators across space and time, as well as understanding agriculture, the hydrological cycle, and the water-food nexus. The described projects follow the guidelines for co-developing useable knowledge for sustainable development policy. We show how working closely with stakeholders is essential for transforming NASA Earth observations into accurate, timely, and relevant information for water-food nexus decision support. We conclude with recommendations for continued efforts in using Earth observations for addressing the water-food nexus and the need to incorporate the role of energy for improved food and water security assessments
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- 2019
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36. Joint Editorial: Invigorating hydrological research through journal publications
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Nevil Quinn, Günter Blöschl, András Bárdossy, Attilio Castellarin, Martyn Clark, Christophe Cudennec, Demetris Koutsoyiannis, Upmanu Lall, Lubomir Lichner, Juraj Parajka, Christa D. Peters-Lidard, Graham Sander, Hubert Savenije, Keith Smettem, Harry Vereecken, Alberto Viglione, Patrick Willems, Andy Wood, Ross Woods, Chong-Yu Xu, and Erwin Zehe
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editorial development ,hydrological research ,peer review ,quality control ,scholarly publishing ,River, lake, and water-supply engineering (General) ,TC401-506 ,Physical geography ,GB3-5030 - Abstract
Editors of several journals in the field of hydrology met during the General Assembly of the European Geosciences Union – EGU in Vienna in April 2017. This event was a follow-up of similar meetings held in 2013 and 2015. These meetings enable the group of editors to review the current status of the journals and the publication process, and to share thoughts on future strategies. Journals were represented at the 2017 meeting by their editors, as shown in the list of authors. The main points on invigorating hydrological research through journal publications are communicated in this joint editorial published in the journals listed here.
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- 2018
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37. High-performance lasers for fully integrated silicon nitride photonics
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Heming Wang, Chao Xiang, Warren Jin, Boqiang Shen, Lin Chang, Jonathan D. Peters, Joel Guo, David Kinghorn, Lue Wu, Kerry J. Vahala, Qi-Fan Yang, Weiqiang Xie, Mario J. Paniccia, John E. Bowers, and Paul A. Morton
- Subjects
Materials science ,Science ,Silicon photonics ,Optical communication ,FOS: Physical sciences ,General Physics and Astronomy ,Physics::Optics ,Applied Physics (physics.app-ph) ,Article ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Resonator ,Laser linewidth ,chemistry.chemical_compound ,law ,Physics::Atomic Physics ,Semiconductor lasers ,Multidisciplinary ,business.industry ,Photonic integrated circuit ,Physics - Applied Physics ,General Chemistry ,Laser ,Silicon nitride ,chemistry ,Optoelectronics ,Photonics ,business ,Waveguide ,Optics (physics.optics) ,Physics - Optics - Abstract
Silicon nitride (SiN) waveguides with ultra-low optical loss enable integrated photonic applications including low noise, narrow linewidth lasers, chip-scale nonlinear photonics, and microwave photonics. Lasers are key components to SiN photonic integrated circuits (PICs), but are difficult to fully integrate with low-index SiN waveguides due to their large mismatch with the high-index III-V gain materials. The recent demonstration of multilayer heterogeneous integration provides a practical solution and enabled the first-generation of lasers fully integrated with SiN waveguides. However, a laser with high device yield and high output power at telecommunication wavelengths, where photonics applications are clustered, is still missing, hindered by large mode transition loss, non-optimized cavity design, and a complicated fabrication process. Here, we report high-performance lasers on SiN with tens of milliwatts output power through the SiN waveguide and sub-kHz fundamental linewidth, addressing all the aforementioned issues. We also show Hertz-level fundamental linewidth lasers are achievable with the developed integration techniques. These lasers, together with high-Q SiN resonators, mark a milestone towards a fully integrated low-noise silicon nitride photonics platform. This laser should find potential applications in LIDAR, microwave photonics and coherent optical communications., Achieving high output power and low noise integrated lasers is a major challenge. Here the authors experimentally demonstrate integrated lasers from a Si/SiN heterogeneous platform that shows Hertz-level linewidth, paving the way toward fully integrating low-noise silicon nitride photonics in volume using real devices for lasing.
- Published
- 2021
38. Foliar selenium application reduces late blight severity and incidence in potato and acts as a pathogen growth inhibitor and elicitor of induced plant defence
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David Main, Ashok Somalraju, Rick D. Peters, Bourlaye Fofana, and Jason McCallum
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biology ,Sclerotinia sclerotiorum ,Biofortification ,chemistry.chemical_element ,Plant Science ,biology.organism_classification ,Solanum tuberosum ,Elicitor ,Horticulture ,chemistry ,Phytophthora infestans ,Blight ,Agronomy and Crop Science ,Pathogen ,Selenium - Abstract
Late blight caused by Phytophthora infestans is a serious threat to potato production. Currently, solutions to manage late blight in organic systems are scarce. This study was undertaken to evaluat...
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- 2021
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39. Overexpression of the PTPN22 Autoimmune Risk Variant LYP-620W Fails to Restrain Human CD4+ T Cell Activation
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Leeana D. Peters, Daniel J. Perry, Zhao Han, Clive Wasserfall, Mark A. Atkinson, Lin Zhang, Clayton E. Mathews, Todd M. Brusko, and Priya Saikumar Lakshmi
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T cell ,Cellular differentiation ,Immunology ,Autoimmunity ,Protein tyrosine phosphatase ,Lymphocyte Activation ,medicine.disease_cause ,T-Lymphocytes, Regulatory ,Article ,Immune tolerance ,PTPN22 ,T-Lymphocyte Subsets ,Immune Tolerance ,medicine ,Humans ,Immunology and Allergy ,Signaling Lymphocytic Activation Molecule Associated Protein ,Cells, Cultured ,Cell Proliferation ,Cell growth ,Chemistry ,T-cell receptor ,Genetic Variation ,Cell Differentiation ,Protein Tyrosine Phosphatase, Non-Receptor Type 22 ,medicine.anatomical_structure ,Gene Expression Regulation ,Mutation ,Cancer research ,Immunologic Memory - Abstract
A missense mutation (R620W) of protein tyrosine phosphatase nonreceptor type 22 (PTPN22), which encodes lymphoid-tyrosine phosphatase (LYP), confers genetic risk for multiple autoimmune diseases including type 1 diabetes. LYP has been putatively demonstrated to attenuate proximal T and BCR signaling. However, limited data exist regarding PTPN22 expression within primary T cell subsets and the impact of the type 1 diabetes risk variant on human T cell activity. In this study, we demonstrate endogenous PTPN22 is differentially expressed and dynamically controlled following activation. From control subjects homozygous for the nonrisk allele, we observed 2.1- (p < 0.05) and 3.6-fold (p < 0.001) more PTPN22 transcripts in resting CD4+ memory and regulatory T cells (Tregs), respectively, over naive CD4+ T cells, with expression peaking 24 h postactivation. When LYP was overexpressed in conventional CD4+ T cells, TCR signaling and activation were blunted by LYP-620R (p < 0.001) but only modestly affected by the LYP-620W risk variant versus mock-transfected control, with similar results observed in Tregs. LYP overexpression only impacted proliferation following activation by APCs but not anti-CD3– and anti-CD28–coated microbeads, suggesting LYP modulation of pathways other than TCR. Notably, proliferation was significantly lower with LYP-620R than with LYP-620W overexpression in conventional CD4+ T cells but was similar in Treg. These data indicate that the LYP-620W variant is hypomorphic in the context of human CD4+ T cell activation and may have important implications for therapies seeking to restore immunological tolerance in autoimmune disorders.
- Published
- 2021
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40. Laser soliton microcombs heterogeneously integrated on silicon
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Lin Chang, Tobias J. Kippenberg, Jonathan D. Peters, Wenle Weng, Chao Xiang, Johann Riemensberger, Zeyu Zhang, Rui Ning Wang, Junqiu Liu, Joel Guo, John E. Bowers, Jennifer Selvidge, and Weiqiang Xie
- Subjects
spectroscopy ,diode ,Materials science ,Silicon ,chemistry.chemical_element ,02 engineering and technology ,Substrate (electronics) ,01 natural sciences ,7. Clean energy ,law.invention ,Semiconductor laser theory ,010309 optics ,chemistry.chemical_compound ,law ,0103 physical sciences ,Wafer ,Diode ,comb generation ,Multidisciplinary ,Silicon photonics ,business.industry ,nitride ,021001 nanoscience & nanotechnology ,Laser ,chemistry ,Silicon nitride ,frequency ,Optoelectronics ,0210 nano-technology ,business - Abstract
Silicon photonics enables wafer-scale integration of optical functionalities on chip. Silicon-based laser frequency combs can provide integrated sources of mutually coherent laser lines for terabit-per-second transceivers, parallel coherent light detection and ranging, or photonics-assisted signal processing. We report heterogeneously integrated laser soliton microcombs combining both indium phospide/silicon (InP/Si) semiconductor lasers and ultralow-loss silicon nitride (Si3N4) microresonators on a monolithic silicon substrate. Thousands of devices can be produced from a single wafer by using complementary metal-oxide-semiconductor-compatible techniques. With on-chip electrical control of the laser-microresonator relative optical phase, these devices can output single-soliton microcombs with a 100-gigahertz repetition rate. Furthermore, we observe laser frequency noise reduction due to self-injection locking of the InP/Si laser to the Si3N4 microresonator. Our approach provides a route for large-volume, low-cost manufacturing of narrow-linewidth, chip-based frequency combs for next-generation high-capacity transceivers, data centers, space and mobile platforms.
- Published
- 2021
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41. Drought Variability over the Conterminous United States for the Past Century
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Dennis P. Lettenmaier, Lu Su, David Mocko, Mu Xiao, Michael Barlage, Christa D. Peters-Lidard, Qian Cao, and Dongyue Li
- Subjects
Atmospheric Science ,Environmental science ,Physical geography - Abstract
We examine the drought variability over the conterminous United States (CONUS) for 1915–2018 using the Noah-MP land surface model. We examine different model options on drought reconstruction, including optional representation of groundwater and dynamic vegetation phenology. Over our 104-yr reconstruction period, we identify 12 great droughts that each covered at least 36% of CONUS and lasted for at least 5 months. The great droughts tend to have smaller areas when groundwater and/or dynamic vegetation are included in the model configuration. We detect a small decreasing trend in dry area coverage over CONUS in all configurations. We identify 45 major droughts in the baseline (with a dry area coverage greater than 23.6% of CONUS) that are, on average, somewhat less severe than great droughts. We find that representation of groundwater tends to increase drought duration for both great and major droughts, primarily by leading to earlier drought onset (some due to short-lived recovery from a previous drought) or later demise (groundwater anomalies lag precipitation anomalies). In contrast, representation of dynamic vegetation tends to shorten major droughts duration, primarily due to earlier drought demise (closed stoma or dead vegetation reduces ET loss during droughts). On a regional basis, the U.S. Southwest (Southeast) has the longest (shortest) major drought durations. Consistent with earlier work, dry area coverage in all subregions except the Southwest has decreased. The effects of groundwater and dynamic vegetation vary regionally due to differences in groundwater depths (hence connectivity with the surface) and vegetation types.
- Published
- 2021
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42. Assimilation of Vegetation Conditions Improves the Representation of Drought over Agricultural Areas
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Shugong Wang, Christa D. Peters-Lidard, Sujay V. Kumar, and David Mocko
- Subjects
Atmospheric Science ,Agriculture ,business.industry ,Representation (systemics) ,medicine ,Environmental science ,Assimilation (biology) ,Physical geography ,medicine.symptom ,business ,Vegetation (pathology) - Abstract
This study presents an evaluation of the impact of vegetation conditions on a land surface model (LSM) simulation of agricultural drought. The Noah-MP LSM is used to simulate water and energy fluxes and states, which are transformed into drought categories using percentiles over the continental United States from 1979 to 2017. Leaf area index (LAI) observations are assimilated into the dynamic vegetation scheme of Noah-MP. A weekly operational drought monitor (the U.S. Drought Monitor) is used for the evaluation. The results show that LAI assimilation into Noah-MP’s dynamic vegetation scheme improves the model’s ability to represent drought, particularly over cropland areas. LAI assimilation improves the simulation of the drought category, detection of drought conditions, and reduces the instances of drought false alarms. The assimilation of LAI in these locations not only corrects model errors in the simulation of vegetation, but also can help to represent unmodeled physical processes such as irrigation toward improved simulation of agricultural drought.
- Published
- 2021
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43. Advances in Land Surface Models and Indicators for Drought Monitoring and Prediction
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Dennis P. Lettenmaier, Lu Su, David Mocko, Christa D. Peters-Lidard, Michael Barlage, and Pierre Gentine
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Surface (mathematics) ,Atmospheric Science ,Climatology ,Environmental science - Abstract
Millions of people across the globe are affected by droughts every year, and recent droughts have highlighted the considerable agricultural impacts and economic costs of these events. Monitoring the state of droughts depends on integrating multiple indicators that each capture particular aspects of hydrologic impact and various types and phases of drought. As the capabilities of land surface models and remote sensing have improved, important physical processes such as dynamic, interactive vegetation phenology, groundwater, and snowpack evolution now support a range of drought indicators that better reflect coupled water, energy, and carbon cycle processes. In this work, we discuss these advances, including newer classes of indicators that can be applied to improve the characterization of drought onset, severity, and duration. We utilize a new model-based drought reconstruction to illustrate the role of dynamic phenology and groundwater in drought assessment. Further, through case studies on flash droughts, snow droughts, and drought recovery, we illustrate the potential advantages of advanced model physics and observational capabilities, especially from remote sensing, in characterizing droughts.
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- 2021
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44. Performance of the Goddard multiscale modeling framework with Goddard ice microphysical schemes
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Jiun‐Dar Chern, Wei‐Kuo Tao, Stephen E. Lang, Toshihisa Matsui, J.‐L. F. Li, Karen I. Mohr, Gail M. Skofronick‐Jackson, and Christa D. Peters‐Lidard
- Published
- 2016
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45. High-Resolution SMAP Satellite Soil Moisture Product: Exploring the Opportunities
- Author
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Christopher Hain, K. Gavahi, Qingyun Duan, Mohammadsepehr Karimiziarani, Sujay V. Kumar, Peyman Abbaszadeh, Hamid Moradkhani, Xiwu Zhan, and Christa D. Peters-Lidard
- Subjects
Atmospheric Science ,Product (mathematics) ,Environmental science ,High resolution ,Satellite ,Water content ,Remote sensing - Published
- 2021
- Full Text
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46. Daily Rainfall Estimate by Emissivity Temporal Variation from 10 Satellites
- Author
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Sarah Ringerud, Christa D. Peters-Lidard, Yalei You, and S. Joseph Munchak
- Subjects
Atmospheric Science ,Emissivity ,Environmental science ,Variation (astronomy) ,Atmospheric sciences - Abstract
Rainfall retrieval algorithms for passive microwave radiometers often exploit the brightness temperature depression due to ice scattering at high-frequency channels (≥85 GHz) over land. This study presents an alternate method to estimate the daily rainfall amount using the emissivity temporal variation (i.e., Δe) under rain-free conditions at low-frequency channels (19, 24, and 37 GHz). Emissivity is derived from 10 passive microwave radiometers, including the Global Precipitation Measurement (GPM) Microwave Imager (GMI), the Advanced Microwave Scanning Radiometer 2 (AMSR2), three Special Sensor Microwave Imager/Sounders (SSMIS), the Advanced Technology Microwave Sounder (ATMS), and four Advanced Microwave Sounding Units-A (AMSU-A). Four different satellite combination schemes are used to derive the Δe for daily rainfall estimates. They are all 10 satellites, 5 imagers, 6 satellites with very different equator crossing times, and GMI only. Results show that Δe from all 10 satellites has the best performance with a correlation of 0.60 and RMSE of 6.52 mm, compared with the Integrated Multisatellite Retrievals for GPM (IMERG) Final run product. The 6-satellites scheme has comparable performance with the all-10-satellites scheme. The 5-imagers scheme performs noticeably worse with a correlation of 0.49 and RMSE of 7.28 mm, while the GMI-only scheme performs the worst with a correlation of 0.25 and RMSE of 11.36 mm. The inferior performance from the 5-imagers and GMI-only schemes can be explained by the much longer revisit time, which cannot accurately capture the emissivity temporal variation.
- Published
- 2021
- Full Text
- View/download PDF
47. Longitudinal investigation of the relationship between omega-3 polyunsaturated fatty acids and neuropsychological functioning in recent-onset psychosis: A randomized clinical trial
- Author
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Bart D. Peters, Usha Govindarajulu, Philip R. Szeszko, Robert K. McNamara, Juan A. Gallego, Delbert G. Robinson, and Anil K. Malhotra
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Psychosis ,medicine.medical_specialty ,Docosahexaenoic Acids ,Article ,law.invention ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Randomized controlled trial ,law ,Internal medicine ,Fatty Acids, Omega-3 ,Brief Psychiatric Rating Scale ,medicine ,Humans ,Biological Psychiatry ,chemistry.chemical_classification ,business.industry ,Neuropsychology ,Risperidone ,medicine.disease ,Eicosapentaenoic acid ,030227 psychiatry ,Psychiatry and Mental health ,Eicosapentaenoic Acid ,Psychotic Disorders ,chemistry ,Docosahexaenoic acid ,Dietary Supplements ,Fatty Acids, Unsaturated ,lipids (amino acids, peptides, and proteins) ,Docosapentaenoic acid ,business ,030217 neurology & neurosurgery ,Polyunsaturated fatty acid - Abstract
Alterations in polyunsaturated fatty acids (PUFAs), including omega-3 and omega-6, have been implicated in the pathophysiology of psychotic disorders, but little is known about their associations with neuropsychological functioning. The present study includes 46 recent-onset psychosis patients who participated in a larger (n = 50) double blind, placebo-controlled randomized clinical trial comparing 16 weeks of treatment with either risperidone + fish oil (FO) (EPA 740 mg and DHA 400 mg daily) or risperidone + placebo and completed neuropsychological assessments at the baseline timepoint. We investigated the relationship between baseline omega-3 (i.e., eicosapentaenoic acid, EPA; docosapentaenoic acid, DPA and docosahexaenoic acid, DHA) and omega-6 (i.e., arachidonic acid, AA) PUFA with baseline MATRICS Consensus Cognitive Battery (MCCB) and Brief Psychiatric Rating Scale (BPRS) scores. Twenty-five patients had neuropsychological data available at 16 weeks following participation in the clinical trial, which included 12 patients assigned to risperidone + FO and 13 patients assigned to risperidone + placebo. At baseline both higher DHA and EPA correlated significantly with better social cognition after controlling for functioning on other neuropsychological domains, total BPRS score, AA level and substance use. Also, at baseline higher AA correlated significantly with hostility/uncooperativeness after controlling for DHA + EPA + DPA, overall neuropsychological functioning and substance use. Patients treated with risperidone + FO demonstrated a significant longitudinal increase in social cognition that was significantly higher at 16 weeks compared to patients treated with risperidone + placebo. DHA also correlated significantly with social cognition at the 16-week timepoint. This study provides novel evidence for a differential role of omega-3 vs. omega-6 PUFA in neuropsychological deficits and symptoms in recent-onset psychosis and its treatment.
- Published
- 2021
- Full Text
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48. Groundwater Recharge Estimated by Land Surface Models: An Evaluation in the Conterminous United States
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Christa D. Peters-Lidard, David Mocko, Bailing Li, Sujay V. Kumar, Jessica M. Erlingis, and Matthew Rodell
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Hydrology ,Atmospheric Science ,Environmental science ,Groundwater recharge - Abstract
Estimating diffuse recharge of precipitation is fundamental to assessing groundwater sustainability. Diffuse recharge is also the process through which climate and climate change directly affect groundwater. In this study, we evaluated diffuse recharge over the conterminous United States simulated by a suite of land surface models (LSMs) that were forced using a common set of meteorological input data. Simulated annual recharge exhibited spatial patterns that were similar among the LSMs, with the highest values in the eastern United States and Pacific Northwest. However, the magnitudes of annual recharge varied significantly among the models and were associated with differences in simulated ET, runoff, and snow. Evaluation against two independent datasets did not answer the question of whether the ensemble mean performs the best, due to inconsistency between those datasets. The amplitude and timing of seasonal maximum recharge differed among the models, influenced strongly by model physics governing deep soil moisture drainage rates and, in cold regions, snowmelt. Evaluation using in situ soil moisture observations suggested that true recharge peaks 1–3 months later than simulated recharge, indicating systematic biases in simulating deep soil moisture. However, recharge from lateral flows and through preferential flows cannot be inferred from soil moisture data, and the seasonal cycle of simulated groundwater storage actually compared well with in situ groundwater observations. Long-term trends in recharge were not consistently correlated with either precipitation trends or temperature trends. This study highlights the need to employ dynamic flow models in LSMs, among other improvements, to enable more accurate simulation of recharge.
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- 2021
- Full Text
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49. Applications of Dynamic Land Surface Information for Passive Microwave Precipitation Retrieval
- Author
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Sarah Ringerud, Christa D. Peters-Lidard, Yalei You, and Joe Munchak
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Atmospheric Science ,Radiometer ,010504 meteorology & atmospheric sciences ,Optimal estimation ,010505 oceanography ,Ocean Engineering ,01 natural sciences ,Article ,law.invention ,law ,Emissivity ,Environmental science ,Gprof ,Satellite ,Radar ,Global Precipitation Measurement ,Microwave ,0105 earth and related environmental sciences ,Remote sensing - Abstract
Accurate, physically based precipitation retrieval over global land surfaces is an important goal of the NASA/JAXA Global Precipitation Measurement Mission (GPM). This is a difficult problem for the passive microwave constellation, as the signal over radiometrically warm land surfaces in the microwave frequencies means that the measurements used are indirect and typically require inferring some type of relationship between an observed scattering signal and precipitation at the surface. GPM, with collocated radiometer and dual-frequency radar, is an excellent tool for tackling this problem and improving global retrievals. In the years following the launch of the GPM Core Observatory satellite, physically based passive microwave retrieval of precipitation over land continues to be challenging. Validation efforts suggest that the operational GPM passive microwave algorithm, the Goddard profiling algorithm (GPROF), tends to overestimate precipitation at the low (−1) end of the distribution over land. In this work, retrieval sensitivities to dynamic surface conditions are explored through enhancement of the algorithm with dynamic, retrieved information from a GPM-derived optimal estimation scheme. The retrieved parameters describing surface and background characteristics replace current static or ancillary GPROF information including emissivity, water vapor, and snow cover. Results show that adding this information decreases probability of false detection by 50% and, most importantly, the enhancements with retrieved parameters move the retrieval away from dependence on ancillary datasets and lead to improved physical consistency.
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- 2021
- Full Text
- View/download PDF
50. Morphology Induced Spinodal Decomposition at the Surface of Symmetric Diblock Copolymer Films
- Author
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Kari Dalnoki-Veress, Robert D. Peters, Pawel Stasiak, and Mark W. Matsen
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Spinodal ,Materials science ,Polymers and Plastics ,Condensed matter physics ,Spinodal decomposition ,media_common.quotation_subject ,Organic Chemistry ,Frustration ,Substrate (electronics) ,Condensed Matter::Soft Condensed Matter ,Inorganic Chemistry ,Condensed Matter::Materials Science ,Crystallography ,Condensed Matter::Superconductivity ,Phase (matter) ,Free surface ,Materials Chemistry ,Perpendicular ,Lamellar structure ,media_common - Abstract
Atomic force microscopy is used to study the ordering dynamics of symmetric diblock copolymer films. The films order to form a lamellar structure which results in a frustration when the film thickness is incommensurate with the lamellae. By probing the morphology of incommensurate films in the early ordering stages, we discover an intermediate phase of lamellae arranged perpendicular to the film surface. This morphology is accompanied by a continuous growth in amplitude of the film surface topography with a characteristic wavelength, indicative of a spinodal process. Using self-consistent field theory, we show that the observation of perpendicular lamellae suggests an intermediate state with parallel lamellae at the substrate and perpendicular lamellae at the free surface. The calculations confirm that the intermediate state is unstable to thickness fluctuations, thereby driving the spinodal growth of surface structures.
- Published
- 2022
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