446 results on '"Browell, Edward V."'
Search Results
2. Spectroscopic measurements of a CO2 absorption line in an open vertical path using an airborne lidar
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Ramanathan, Anand, Mao, Jianping, Allan, Graham R, Riris, Haris, Weaver, Clark J, Hasselbrack, William E, Browell, Edward V, and Abshire, James B
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Physics - Atmospheric and Oceanic Physics ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We use an airborne pulsed integrated path differential absorption lidar to make spectroscopic measurements of the pressure-induced line broadening and line center shift of atmospheric CO2 at the 1572.335 nm absorption line. We measure the absorption lineshape in the vertical column between the aircraft and ground. A comparison of our measured absorption lineshape to calculations based on HITRAN shows excellent agreement with the peak optical depth accurate to within 0.3%. Additionally, we measure changes in the line center position to within 5.2 MHz of calculations, and the absorption linewidth to within 0.6% of calculations., Comment: 4 pages, 4 figures, Submitted to Applied Physics Letters
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- 2013
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3. Asian outflow and trans‐Pacific transport of carbon monoxide and ozone pollution: An integrated satellite, aircraft, and model perspective
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Heald, Colette L, Jacob, Daniel J, Fiore, Arlene M, Emmons, Louisa K, Gille, John C, Deeter, Merritt N, Warner, Juying, Edwards, David P, Crawford, James H, Hamlin, Amy J, Sachse, Glen W, Browell, Edward V, Avery, Melody A, Vay, Stephanie A, Westberg, David J, Blake, Donald R, Singh, Hanwant B, Sandholm, Scott T, Talbot, Robert W, and Fuelberg, Henry E
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Climate Action ,TRACE-P ,MOPITT ,Asian pollution ,trans-Pacific transport ,carbon monoxide ,O-3 production ,Meteorology & Atmospheric Sciences - Published
- 2003
4. Ozone, aerosol, potential vorticity, and trace gas trends observed at high‐latitudes over North America from February to May 2000
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Browell, Edward V, Hair, Johnathan W, Butler, Carolyn F, Grant, William B, DeYoung, Russell J, Fenn, Marta A, Brackett, Vince G, Clayton, Marian B, Brasseur, Lorraine A, Harper, David B, Ridley, Brian A, Klonecki, Andrzej A, Hess, Peter G, Emmons, Louisa K, Tie, Xuexi, Atlas, Elliot L, Cantrell, Christopher A, Wimmers, Anthony J, Blake, Donald R, Coffey, Michael T, Hannigan, James W, Dibb, Jack E, Talbot, Robert W, Flocke, Frank, Weinheimer, Andrew J, Fried, Alan, Wert, Bryan, Snow, Julie A, and Lefer, Barry L
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Climate Action ,ozone ,aerosols ,springtime ,Arctic ,trends ,Meteorology & Atmospheric Sciences - Published
- 2003
5. Large‐scale ozone and aerosol distributions, air mass characteristics, and ozone fluxes over the western Pacific Ocean in late winter/early spring
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Browell, Edward V, Fenn, Marta A, Butler, Carolyn F, Grant, William B, Brackett, Vincent G, Hair, Johnathan W, Avery, Melody A, Newell, Reginald E, Hu, Yuanlong, Fuelberg, Henry E, Jacob, Daniel J, Anderson, Bruce E, Atlas, Elliot L, Blake, Donald R, Brune, William H, Dibb, Jack E, Fried, Alan, Heikes, Brian G, Sachse, Glen W, Sandholm, Scott T, Singh, Hanwant B, Talbot, Robert W, Vay, Stephanie A, Weber, Rodney J, and Bartlett, Karen B
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Earth Sciences ,Atmospheric Sciences ,ozone ,aerosols ,fluxes ,air mass characteristics ,western Pacific ,TRACE-P ,Meteorology & Atmospheric Sciences - Published
- 2003
6. Large‐scale air mass characteristics observed over the remote tropical Pacific Ocean during March‐April 1999: Results from PEM‐Tropics B field experiment
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Browell, Edward V, Fenn, Marta A, Butler, Carolyn F, Grant, William B, Ismail, Syed, Ferrare, Richard A, Kooi, Susan A, Brackett, Vincent G, Clayton, Marian B, Avery, Melody A, Barrick, John DW, Fuelberg, Henry E, Maloney, Joseph C, Newell, Reginald E, Zhu, Yong, Mahoney, Michael J, Anderson, Bruce E, Blake, Donald R, Brune, William H, Heikes, Brian G, Sachse, Glen W, Singh, Hanwant B, and Talbot, Robert W
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Climate Action ,Meteorology & Atmospheric Sciences - Abstract
Eighteen long-range flights over the Pacific Ocean between 38° S to 20° N and 166° E to 90° W were made by the NASA DC-8 aircraft during the NASA Pacific Exploratory Mission (PEM) Tropics B conducted from March 6 to April 18, 1999. Two lidar systems were flown on the DC-8 to remotely measure vertical profiles of ozone (O3), water vapor (H2O), aerosols, and clouds from near the surface to the upper troposphere along their flight track. In situ measurements of a wide range of gases and aerosols were made on the DC-8 for comprehensive characterization of the air and for correlation with the lidar remote measurements. The transition from northeasterly flow of Northern Hemispheric (NH) air on the northern side of the Intertropical Convergence Zone (ITCZ) to generally easterly flow of Southern Hemispheric (SH) air south of the ITCZ was accompanied by a significant decrease in O3, carbon monoxide, hydrocarbons, and aerosols and an increase in H2O. Trajectory analyses indicate that air north of the ITCZ came from Asia and/or the United States, while the air south of the ITCZ had a long residence time over the Pacific, perhaps originating over South America several weeks earlier. Air south of the South Pacific Convergence Zone (SPCZ) came rapidly from the west originating over Australia or Africa. This air had enhanced O3 and aerosols and an associated decrease in H2O. Average latitudinal and longitudinal distributions of O3 and H2O were constructed from the remote and in situ O3 and H2O data, and these distributions are compared with results from PEM-Tropics A conducted in August-October 1996. During PEM-Tropics B, low O3 air was found in the SH across the entire Pacific Basin at low latitudes. This was in strong contrast to the photochemically enhanced O3 levels found across the central and eastern Pacific low latitudes during PEM-Tropics A. Nine air mass types were identified for PEM-Tropics B based on their O3, aerosols, clouds, and potential vorticity characteristics. The data from each flight were binned by altitude according to air mass type, and these results showed the relative observational frequency of the different air masses as a function of altitude in seven regions over the Pacific. The average chemical composition of the major air mass types was determined from in situ measurements in the NH and SH, and these results provided insight into the origin, lifetime, and chemistry of the air in these regions. Copyright 2001 by the American Geophysical Union.
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- 2001
7. A case study of transport of tropical marine boundary layer and lower tropospheric air masses to the northern midlatitude upper troposphere
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Grant, William B, Browell, Edward V, Butler, Carolyn F, Fenn, Marta A, Clayton, Marian B, Hannan, John R, Fuelberg, Henry E, Blake, Donald R, Blake, Nicola J, Gregory, Gerald L, Heikes, Brian G, Sachse, Glen W, Singh, Hanwant B, Snow, Julie, and Talbot, Robert W
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Climate Action ,Meteorology & Atmospheric Sciences - Abstract
Low-ozone (
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- 2000
8. Ozone and aerosol distributions and air mass characteristics over the South Pacific during the burning season
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Fenn, Marta A, Browell, Edward V, Butler, Carolyn F, Grant, William B, Kooi, Susan A, Clayton, Marian B, Gregory, Gerald L, Newell, Reginald E, Zhu, Yong, Dibb, Jack E, Fuelberg, Henry E, Anderson, Bruce E, Bandy, Alan R, Blake, Donald R, Bradshaw, John D, Heikes, Brian G, Sachse, Glen W, Sandholm, Scott T, Singh, Hanwant B, Talbot, Robert W, and Thornton, Donald C
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Climate Action ,Meteorology & Atmospheric Sciences - Abstract
In situ and laser remote measurements of gases and aerosols were made with airborne instrumentation to establish a baseline chemical signature of the atmosphere above the South Pacific Ocean during the NASA Global Tropospheric Experiment (GTE)/Pacific Exploratory Mission-Tropics A (PEM-Tropics A) conducted in August-October 1996. This paper discusses general characteristics of the air masses encountered during this experiment using an airborne lidar system for measurements of the large-scale variations in ozone (O3) and aerosol distributions across the troposphere, calculated potential vorticity (PV) from the European Centre for Medium-Range Weather Forecasting (ECMWF), and in situ measurements for comprehensive air mass composition. Between 8° S and 52° S, biomass burning plumes containing elevated levels of O3, over 100 ppbv, were frequently encountered by the aircraft at altitudes ranging from 2 to 9 km. Air with elevated O3 was also observed remotely up to the tropopause, and these air masses were observed to have no enhanced aerosol loading. Frequently, these air masses had some enhanced PV associated with them, but not enough to explain the observed O3 levels. A relationship between PV and O3 was developed from cases of clearly defined O3 from stratospheric origin, and this relationship was used to estimate the stratospheric contribution to the air masses containing elevated O3 in the troposphere. The frequency of observation of the different air mass types and their average chemical composition is discussed in this paper. Copyright 1999 by the American Geophysical Union.
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- 1999
9. A meteorological overview of the Pacific Exploratory Mission (PEM) Tropics period
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Fuelberg, Henry E, Newell, Reginald E, Longmore, Scott P, Zhu, Yong, Westberg, David J, Browell, Edward V, Blake, Donald R, Gregory, Gerald L, and Sachse, Glen W
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Climate Action ,Meteorology & Atmospheric Sciences - Abstract
NASA's Pacific Exploratory Mission-Tropics (PEM-T) experiment investigated the atmospheric chemistry of a large portion of the tropical and subtropical Pacific Basin during August to October 1996. This paper summarizes meteorological conditions over the PEM-T domain. Mean flow patterns during PEM-T are described. Important circulation systems near the surface include subtropical anticyclones, the South Pacific Convergence Zone (SPCZ), the Intertropical Convergence Zone (ITCZ), and middle latitude transient cyclones. The SPCZ and ITCZ are areas of widespread ascent and deep convection; however, there is relatively little lightning in these oceanic regions. A large area of subsidence is associated with the subtropical anticyclone centered near Easter Island. PEM-T occurred during a period of near normal sea surface temperatures. When compared to an 11 year climatology (1986-1996), relatively minor circulation anomalies are observed during PEM-T. Some of these circulation anomalies are consistent with much stronger anomalies observed during previous La Nina events. In general, however, the 1996 PEM-T period appears to be climatologically representative. Meteorological conditions for specific flights from each major operations area are summarized. The vertical distribution of ozone along selected DC-8 flights is described using the DIAL remote sensing system. These ozone distributions are related to thermodynamic soundings obtained during aircraft maneuvers and to backward trajectories that arrived at locations along the flight tracks. Most locations in the deep tropics are found to have relatively small values of tropospheric ozone. Backward trajectories calculated from global gridded analyses show that much of this air originates from the east and has not passed over land within 10 days. The deep convection associated with the ITCZ and SPCZ also influences the atmospheric chemistry of these regions. Flights over portions of the subtropics and middle latitudes document layers of greatly enhanced tropospheric ozone, sometimes exceeding 80 ppbv. In situ carbon monoxide in these layers often exceeds 90 ppbv. These regions are located near, and especially south of Tahiti, Easter Island, and Fiji. The layers of enhanced ozone usually correspond to layers of dry air, associated with widespread subsiding air. The backward trajectories show that air parcels arriving in these regions originate from the west, passing over Australia and even extending back to southern Africa. These are regions of biomass burning. The in situ chemical measurements support the trajectory-derived origins of these ozone plumes. Thus the enhanced tropospheric ozone over the central Pacific Basin may be due to biomass burning many thousands of kilometers away. Middle-latitude portions of the PEM-T area are influenced by transient cyclones, and the DC-8 traversed tropopause folds during several flights. The flight area just west of Ecuador experiences outflow from South America. Thus the biomass burning that is prevalent over portions of Brazil influences this area. Copyright 1999 by the American Geophysical Union.
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- 1999
10. On the origin of tropospheric ozone and NOx over the tropical South Pacific
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Schultz, Martin G, Jacob, Daniel J, Wang, Yuhang, Logan, Jennifer A, Atlas, Elliot L, Blake, Donald R, Blake, Nicola J, Bradshaw, John D, Browell, Edward V, Fenn, Marta A, Flocke, Frank, Gregory, Gerald L, Heikes, Brian G, Sachse, Glen W, Sandholm, Scott T, Shetter, Richard E, Singh, Hanwant B, and Talbot, Robert W
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Climate Action ,Meteorology & Atmospheric Sciences - Abstract
The budgets of ozone and nitrogen oxides (NOx = NO + NO2) in the tropical South Pacific troposphere are analyzed by photochemical point modeling of aircraft observations at 0-12 km altitude from the Pacific Exploratory Mission-Tropics A campaign flown in September-October 1996. The model reproduces the observed NO2/NO concentration ratio to within 30% and has similar success in simulating observed concentrations of peroxides (H2O2, CH3OOH), lending confidence in its use to investigate ozone chemistry. It is found that chemical production of ozone balances only half of chemical loss in the tropospheric column over the tropical South Pacific. The net loss is 1.8 x 1011 molecules cm-2 s-1. The missing source of ozone is matched by westerly transport of continental pollution into the region. Independent analysis of the regional ozone budget with a global three-dimensional model corroborates the results from the point model and reveals the importance of biomass burning emissions in South America and Africa for the ozone budget over the tropical South Pacific. In this model, biomass burning increases average ozone concentrations by 7-8 ppbv throughout the troposphere. The NOx responsible for ozone production within the South Pacific troposphere below 4 km can be largely explained by decomposition of peroxyacetylnitrate (PAN) transported into the region with biomass burning pollution at higher altitudes. Copyright 1999 by the American Geophysical Union.
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- 1999
11. Aerosols from biomass burning over the tropical South Atlantic region: Distributions and impacts
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Anderson, Bruce E, Grant, William B, Gregory, Gerald L, Browell, Edward V, Collins, James E, Sachse, Glen W, Bagwell, Donald R, Hudgins, Charles H, Blake, Donald R, and Blake, Nicola J
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Climate Action ,Meteorology & Atmospheric Sciences - Abstract
The NASA Global Tropospheric Experiment (GTE) Transport and Atmospheric Chemistry Near the Equator-Atlantic (TRACE A) expedition was conducted September 21 through October 26, 1992, to investigate factors responsible for creating the seasonal South Atlantic tropospheric ozone maximum. During these flights, fine aerosol (0.1-3.0 μm) number densities were observed to be enhanced roughly tenfold over remote regions of the tropical South Atlantic and greater over adjacent continental areas, relative to northern hemisphere observations and to measurements recorded in the same area during Ac wet season. Chemical and meteorological analyses as well as visual observations indicate that the primary source of these enhancements was biomass burning occurring within grassland regions of north central Brazil and southeastern Africa. These fires exhibited fine aerosol (N) emission ratios relative to CO (dN/dCO) of 22.5 ± 9.7 and 23.6 ± 15.1 cm-3 parts per billion by volume (ppbv)-1 over Brazil and Africa, respectively. Convection coupled with counterclockwise flow around the South Atlantic subtropical anticyclone subsequently distributed these aerosols throughout the remote South Atlantic troposphere. We calculate that dilute smoke from biomass burning produced an average tenfold enhancement in optical depth over the continental regions as well as a 50% increase in this parameter over the middle South Atlantic Ocean; these changes correspond to an estimated net cooling of up to 25 W m-2 and 2.4 W m-2 during clear-sky conditions over savannas and ocean respectively. Over the ocean our analyses suggest that modification of CCN concentrations within the persistent eastern Atlantic marine stratocumulus clouds by entrainment of subsiding haze layers could significantly increase cloud albedo resulting in an additional surface radiative cooling potentially greater in magnitude than that caused by direct extinction of solar radiation by the aerosol particles themselves.
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- 1996
12. PEM‐West A: Meteorological overview
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Bachmeier, A Scott, Newell, Reginald E, Shipham, Mark C, Zhu, Yong, Blake, Donald R, and Browell, Edward V
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Meteorology & Atmospheric Sciences - Abstract
Phase A of the NASA Pacific Exploratory Mission in the western North Pacific (PEM-West A) region was conducted during September-October 1991. The background meteorology of eastern Asia and the western North Pacific region during the PEM-West A study is described. Mean large-scale flow patterns are discussed along with transient synoptic scale features (e.g., midlatitude cyclones, anticyclones, and frontal systems) responsible for long-range transport of trace species over the study region. Synoptic summaries are given for each of the 18 data flights, together with selected examples of meteorological processes that gave rise to some of the changes observed in the measured trace gases. Examples of large-scale ozone features observed above and below the DC-8 flight altitude by an onboard lidar system are also related to meteorological processes such as stratospheric-tropospheric exchange and upward transport of air from the boundary layer. Copyright 1996 by the American Geophysical Union.
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- 1996
13. Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS): Final Report of the ASCENDS Ad Hoc Science Definition Team
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Kawa, S. Randolph, Abshire, James B, Baker, David F, Browell, Edward V, Crisp, David, Crowell, Sean M.R, Hyon, Jason J, Jacob, Joseph C, Jucks, Kenneth W, Lin, Bing, Menzies, Robert T, Ott, Lesley E, and Zaccheo, T. Scott
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Geosciences (General) - Abstract
Improved remote sensing observations of atmospheric carbon dioxide (CO2) are critically needed to quantify, monitor, and understand the Earth's carbon cycle and its evolution in a changing climate. The processes governing ocean and terrestrial carbon uptake remain poorly understood,especially in dynamic regions with large carbon stocks and strong vulnerability to climate change,for example, the tropical land biosphere, the northern hemisphere high latitudes, and the Southern Ocean. Because the passive spectrometers used by GOSAT (Greenhouse gases Observing SATellite) and OCO-2 (Orbiting Carbon Observatory-2) require sunlit and cloud-free conditions,current observations over these regions remain infrequent and are subject to biases. These short comings limit our ability to understand and predict the processes controlling the carbon cycle on regional to global scales.In contrast, active CO2 remote-sensing techniques allow accurate measurements to be taken day and night, over ocean and land surfaces, in the presence of thin or scattered clouds, and at all times of year. Because of these benefits, the National Research Council recommended the National Aeronautics and Space Administration (NASA) Active Sensing of CO2 Emissions over Nights,Days, and Seasons (ASCENDS) mission in the 2007 report Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond. The ability of ASCENDS to collect low-bias observations in these key regions is expected to address important gaps in our knowledge of the contemporary carbon cycle.The ASCENDS ad hoc Science Definition Team (SDT), comprised of carbon cycle modeling and active remote sensing instrument teams throughout the United States (US), worked to develop the mission's requirements and advance its readiness from 2008 through 2018. Numerous scientific investigations were carried out to identify the benefit and feasibility of active CO2 remote sensing measurements for improving our understanding of CO2 sources and sinks. This report summarizes their findings and recommendations based on mission modeling studies, analysis of ancillary meteorological data products, development and demonstration of candidate technologies, anddesign studies of the ASCENDS mission concept.
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- 2018
14. Advancements Towards Active Remote Sensing of CO2 from Space Using Intensity-Modulated, Continuous-Wave (IM-CW) Lidar
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Obland, Michael D, Corbett, Abigail M, Lin, Bing, Meadows, Byron, Campbell, Joel F, Kooi, Susan, Fan, Tai-Fang, Carrion, William, Hicks, Jonathan, Sparrow, Joseph, Browell, Edward V, Dobler, Jeremy, and DiGangi, Josh
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Earth Resources And Remote Sensing - Abstract
The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) CarbonHawk Experiment Simulator (ACES) is a NASA Langley Research Center instrument funded by NASA’s Science Mission Directorate that seeks to advance technologies critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA ASCENDS mission. The ACES instrument, an Intensity-Modulated Continuous-Wave (IM-CW) lidar, was designed for high-altitude aircraft operations and can be directly applied to space instrumentation to meet the ASCENDS mission requirements. The ACES design demonstrates advanced technologies critical for developing an airborne simulator and spaceborne instrument with lower platform consumption of size, mass, and power, and with improved performance. ACES recently flew on the NASA DC-8 aircraft during the 2017 NASA ASCENDS/Arctic-Boreal Vulnerability Experiment (ABoVE) airborne measurement campaign to test ASCENDS-related technologies in the challenging Arctic environment. Data were collected over a wide variety of surface reflectivities, terrain, and atmospheric conditions during the campaign’s 8 research flights. ACES also flew during the 2017 and 2018 Atmospheric Carbon and Transport – America (ACT-America) Earth Venture Suborbital -2 (EVS-2) campaigns along with the primary ACT-America CO2 lidar, Harris Corporation’s Multi-Frequency Fiber Laser Lidar (MFLL). Regional CO2 distributions of the lower atmosphere were observed from the C-130 aircraft during the ACT-America campaigns in support of ACT-America’s science objectives. The airborne lidars provide unique data that complement the more traditional in situ sensors. This presentation shows the applications of CO2 lidars in meeting these science needs from airborne platforms and an eventual spacecraft.
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- 2018
15. On the Ability of Space- Based Passive and Active Remote Sensing Observations of CO2 to Detect Flux Perturbations to the Carbon Cycle
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Crowell, Sean M. R, Kawa, S. Randolph, Browell, Edward V, Hammerling, Dorit M, Moore, Berrien, Schaefer, Kevin, and Doney, Scott C
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Earth Resources And Remote Sensing ,Environment Pollution - Abstract
Space-borne observations of CO2 are vital to gaining understanding of the carbon cycle in regions of the world that are difficult to measure directly, such as the tropical terrestrial biosphere, the high northern and southern latitudes, and in developing nations such as China. Measurements from passive instruments such as GOSAT (Greenhouse Gases Observing Satellite) and OCO-2 (Orbiting Carbon Observatory 2), however, are constrained by solar zenith angle limitations as well as sensitivity to the presence of clouds and aerosols. Active measurements such as those in development for the Active Sensing of CO2 Emissions over Nights, Days and Seasons (ASCENDS) mission show strong potential for making measurements in the high-latitude winter and in cloudy regions. In this work we examine the enhanced flux constraint provided by the improved coverage from an active measurement such as ASCENDS. The simulation studies presented here show that with sufficient precision, ASCENDS will detect permafrost thaw and fossil fuel emissions shifts at annual and seasonal time scales, even in the presence of transport errors, representativeness errors, and biogenic flux errors. While OCO-2 can detect some of these perturbations at the annual scale, the seasonal sampling provided by ASCENDS provides the stronger constraint. Plain Language Summary: Active and passive remote sensors show the potential to provide unprecedented information on the carbon cycle. With the all-season sampling, active remote sensors are more capable of constraining high-latitude emissions. The reduced sensitivity to cloud and aerosol also makes active sensors more capable of providing information in cloudy and polluted scenes with sufficient accuracy. These experiments account for errors that are fundamental to the top-down approach for constraining emissions, and even including these sources of error, we show that satellite remote sensors are critical for understanding the carbon cycle.
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- 2018
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16. THE SAHARAN AIR LAYER AND THE FATE OF AFRICAN EASTERLY WAVES : NASA’s AMMA Field Study of Tropical Cyclogenesis
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Zipser, Edward J., Twohy, Cynthia H., Tsay, Si-Chee, Thornhill, K. Lee, Tanelli, Simone, Ross, Robert, Krishnamurti, T. N., Ji, Q., Jenkins, Gregory, Ismail, Syed, Hsu, N. Christina, Hood, Robbie, Heymsfield, Gerald M., Heymsfield, Andrew, Halverson, Jeffrey, Goodman, H. Michael, Ferrare, Richard, Dunion, Jason P., Douglas, Michael, Cifelli, Robert, Chen, Gao, Browell, Edward V., and Anderson, Bruce
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- 2009
17. Advanced Airborne UV DIAL System for Stratospheric and Tropospheric Ozone and Aerosol Measurements
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Richter, Dale A., Browell, Edward V., Butler, Carolyn F., Higdon, Noah S., Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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18. Airborne Lidar Measurements of Ozone and Aerosols During PEM-West A and PEM-West B
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Fenn, Marta A., Browell, Edward V., Butler, Carolyn F., Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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19. Advanced Airborne Water Vapor DIAL Development and Measurements
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Chyba, Thomas H., Ponsardin, Patrick, Higdon, Noah S., DeYoung, Russell J., Butler, Carolyn F., Browell, Edward V., Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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20. LASE Validation Experiment
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Browell, Edward V., Ismail, Syed, Hall, William M., Moore, Alvah S., Jr., Kooi, Susan A., Brackett, Vincent G., Clayton, Marian B., Barrick, John D. W., Schmidlin, Frank J., Higdon, N. Scott, Melfi, S. Harvey, Whiteman, David N., Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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21. Development of the Lidar Atmospheric Sensing Experiment (LASE)—An Advanced Airborne DIAL Instrument
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Moore, Alvash S., Jr., Brown, Kevin E., Hall, William M., Barnes, James C., Edwards, William C., Petway, Larry B., Little, Alan D., Luck, William S., Jr., Jones, Irby W., Antill, Charles W., Jr., Browell, Edward V., Ismail, Syed, Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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22. LITE Measurements of Biomass Burning Aerosols and Comparisons with Correlative Airborne Lidar Measurements of Multiple Scattering in the Planetary Boundary Layer
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Grant, William B., Browell, Edward V., Butler, Carolyn F., Nowicki, Gregory D., Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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23. Comparison of Aerosol Measurements by Lidar and In Situ Methods in the Pacific Basin Troposphere
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Redemann, Jens, Turco, Richard P., Pueschel, Rudolf F., Browell, Edward V., Grant, William B., Ansmann, Albert, editor, Neuber, Roland, editor, Rairoux, Patrick, editor, and Wandinger, Ulla, editor
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- 1997
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24. Technology Advancements for Active Remote Sensing of Carbon Dioxide from Space using the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) CarbonHawk Experiment Simulator
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Obland Michael D., Campbell Joel, Kooi Susan, Fan Tai-Fang, Carrion William, Hicks Jonathan, Lin Bing, Nehrir Amin R., Browell Edward V., Meadows Byron, and Davis Kenneth J.
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Physics ,QC1-999 - Abstract
This work describes advances in critical lidar technologies and techniques developed as part of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons CarbonHawk Experiment Simulator system for measuring atmospheric column carbon dioxide (CO2) mixing ratios. This work provides an overview of these technologies and results from recent test flights during the NASA Atmospheric Carbon and Transport – America (ACT-America) Earth Venture Suborbital summer 2016 flight campaign.
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- 2018
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25. Spatial and Temporal Variability of Carbon Dioxide Using Structure Functions in Urban Areas: Insights for Future Active Remote CO2 Sensors
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Choi, Yonghoon, Yang, Melissa, Kooi, Susan A, Browell, Edward V, and DiGangi, Joshua P
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Environment Pollution ,Geophysics ,Earth Resources And Remote Sensing - Abstract
High resolution in-situ CO2 measurements were recorded onboard the NASA P-3B during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) Field Campaigns during July 2011 over Washington DC/Baltimore, MD; January-February 2013 over the San Joaquin Valley, CA; September 2013 over Houston, TX; and July-August 2014 over Denver, CO. Each of these campaigns have approximately two hundred vertical soundings of CO2 within the lower troposphere (surface to about 5 kilometers) at 6-8 different sites in each of the urban areas. In this study, we used structure function analysis, which is a useful way to quantify spatial and temporal variability, by displaying differences with average observations, to evaluate the variability of CO2 in the 0-2 kilometers range (representative of the planetary boundary layer). These results can then be used to provide guidance in the development of science requirements for the future ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) mission to measure near-surface CO2 variability in different urban areas. We also compare the observed in-situ CO2 variability with the variability of the CO2 column-averaged optical depths in the 0-1 kilometer and 0-3.5 kilometers altitude ranges in the four geographically different urban areas, using vertical weighting functions for potential future ASCENDS lidar CO2 sensors operating in the 1.57 and 2.05 millimeter measurement regions. In addition to determining the natural variability of CO2 near the surface and in the column, radiocarbon method using continuous CO2 and CO measurements are used to examine the variation of emission quantification between anthropogenic and biogenic sources in the DC/Maryland urban site.
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- 2015
26. Validation of the Saharan Dust Plume Conceptual Model Using Lidar, Meteosat, and ECMWF Data
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Karyampudi, V. Mohan, Palm, Stephen P., Reagen, John A., Fang, Hui, Grant, William B., Hoff, Raymond M., Moulin, Cyril, Pierce, Harold F., Torres, Omar, Browell, Edward V., and Melfi, S. Harvey
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- 1999
27. Ozone and Aerosol Changes During the 1991-1992 Airborne Arctic Stratospheric Expedition
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Browell, Edward V., Butler, Carolyn F., Fenn, Marta A., Grant, William B., Ismail, Syed, Schoeberl, Mark R., Toon, Owen B., Loewenstein, Max, and Podolske, James R.
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- 1993
28. Signal to Noise Ratio Estimation of the ASCENDS CarbonHawk Experiment Simulator (ACES) for Atmospheric CO2 Measurement
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Chen, Songsheng, Petway, Larry B, Bai, Yingxin, Harrison, Fenton W, Campbell, Joel F, Meadows, Byron L, Lin, Bing, Obland, Michael D, and Browell, Edward V
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Earth Resources And Remote Sensing - Published
- 2015
29. Technology Advancement for Active Remote Sensing of Carbon Dioxide from Space Using the ASCENDS CarbonHawk Experiment Simulator: First Results
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Obland, Michael D, Nehrir, Amin R, Lin, Bing, Harrison, F. Wallace, Kooi, Susan, Choi, Yonghoon, Plant, James, Yang, Melissa, Antill, Charles, Campbell, Joel, Ismail, Syed, Browell, Edward V, Meadows, Byron, Dobler, Jeremy, Zaccheo, T. Scott, Moore, Berrien, and Crowell, Sean
- Subjects
Earth Resources And Remote Sensing - Abstract
The ASCENDS CarbonHawk Experiment Simulator (ACES) is a newly developed lidar developed at NASA Langley Research Center and funded by NASA's Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP) that seeks to advance technologies critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The technology advancements targeted include: (1) increasing the power-aperture product to approach ASCENDS mission requirements by implementing multi-aperture telescopes and multiple co-aligned laser transmitters; (2) incorporating high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) developing and incorporating a high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration autonomous operation on Global Hawk aircraft, and (4) advancing algorithms for cloud and aerosol discrimination. The ACES instrument architecture is being developed for operation on high-altitude aircraft and will be directly scalable to meet the ASCENDS mission requirements. These technologies are critical towards developing not only spaceborne instruments but also their airborne simulators, with lower platform requirements for size, mass, and power, and with improved instrument performance for the ASCENDS mission. ACES transmits five laser beams: three from commercial EDFAs operating near 1.57 microns, and two from the Exelis oxygen (O2) Raman fiber laser amplifier system operating near 1.26 microns. The three EDFAs are capable of transmitting up to 10 watts average optical output power each and are seeded by compact, low noise, stable, narrow-linewidth laser sources stabilized with respect to a CO2 absorption line using a multi-pass gas absorption cell. The Integrated-Path Differential Absorption (IPDA) lidar approach is used at both wavelengths to independently measure the CO2 and O2 column number densities and retrieve the average column CO2 mixing ratio. The ACES receiver uses three fiber-coupled 17.8-cm diameter athermal telescopes. The transmitter assembly consists of five fiber-coupled laser collimators and an associated Risley prism pair for each laser to co-align the outgoing laser beams and to align them with the telescope field of view. The backscattered return signals collected by the three telescopes are combined in a fiber bundle and sent to a single low noise detector. The detector/TIA development has improved the existing detector subsystem by increasing its bandwidth to 4.7 MHz from 500 kHz and increasing the duration of autonomous, service-free operation periods from 4 hours to >24 hours. The new detector subsystem enables the utilization of higher laser modulation rates, which provides greater flexibility for implementing advanced thin-cloud discrimination algorithms as well as improving range-determination resolution and error reduction. The cloud/aerosol discrimination algorithm development by Langley and Exelis features a new suite of algorithms for the minimization/elimination of bias errors in the return signal induced by the presence of intervening thin clouds. Multiple laser modulation schemes are being tested in an effort to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. Full instrument development concluded in the spring of 2014. After ground range tests of the instrument, ACES successfully completed six test flights on the Langley Hu-25 aircraft in July, 2014, and recorded data at multiple altitudes over land and ocean surfaces with and without intervening clouds. Preliminary results from these test flights will be presented in this paper.
- Published
- 2015
30. LASE measurements of water vapor, aerosol, and cloud distributions in Saharan air layers and tropical disturbances
- Author
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Ismail, Syed, Ferrare, Richard A., Browell, Edward V., Kooi, Susan A., Dunion, Jason P., Heymsfield, Gerry, Notari, Anthony, Butler, Carolyn F., Burton, Sharon, Fenn, Marta, Krishnamurti, T.N., Biswas, Mrinal K., Chen, Gao, and Anderson, Bruce
- Subjects
Sensors -- Usage ,Atmospheric physics -- Research ,Earth sciences ,Science and technology - Abstract
The Lidar Atmospheric Sensing Experiment (LASE) on board the NASA DC-8 measured high-resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan air layer (SAL). These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its interactions with AEWs and TCs. Three case studies were selected for detailed analysis: (i) a stratified SAL, with fine structure and layering (unlike a well-mixed SAL), (ii) a SAL with high relative humidity (RH), and (iii) an AEW surrounded by SAL dry air intrusions. Profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in the SAL, convection, and clear air regions. LASE extinction-to-backscatter ratios for the dust layers varied from 35 [+ or -] 5 to 45 [+ or -] 5 sr, well within the range of values determined by other lidar systems. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively. An analysis of LASE data suggests that the SAL suppresses low-altitude convection. Midlevel convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on 20 August 2008. This interaction is responsible for the transfer of about 7 x [10.sup.15] J (or 8 x [10.sup.3] J [m.sup.-2]) latent heat energy within a day to the SAL. Initial modeling studies that used LASE water vapor profiles show sensitivity to and improvements in model forecasts of an AEW. DOI: 10.1175/2009JAS3136.1
- Published
- 2010
31. Measurements of Atmospheric CO2 Column in Cloudy Weather Conditions using An IM-CW Lidar at 1.57 Micron
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Lin Bing, Obland Michael D., Harrison F. Wallace, Nehrir Amin R., Browell Edward V., Ismail Syed, Campbell Joel, Dobler Jeremy, Meadows Byron, Fan Tai-Fang, and Kooi Susan A.
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Physics ,QC1-999 - Published
- 2016
- Full Text
- View/download PDF
32. Performance Simulations for a Spaceborne Methane Lidar Mission
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Kiemle, C, Kawa, Stephan Randolph, Quatrevalet, Mathieu, and Browell, Edward V
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Optics - Abstract
Future spaceborne lidar measurements of key anthropogenic greenhouse gases are expected to close current observational gaps particularly over remote, polar, and aerosol-contaminated regions, where actual in situ and passive remote sensing observation techniques have difficulties. For methane, a "Methane Remote Lidar Mission" was proposed by Deutsches Zentrum fuer Luft- und Raumfahrt and Centre National d'Etudes Spatiales in the frame of a German-French climate monitoring initiative. Simulations assess the performance of this mission with the help of Moderate Resolution Imaging Spectroradiometer and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations of the earth's surface albedo and atmospheric optical depth. These are key environmental parameters for integrated path differential absorption lidar which uses the surface backscatter to measure the total atmospheric methane column. Results showthat a lidar with an average optical power of 0.45W at 1.6 μm wavelength and a telescope diameter of 0.55 m, installed on a low Earth orbit platform(506 km), will measure methane columns at precisions of 1.2%, 1.7%, and 2.1% over land, water, and snow or ice surfaces, respectively, for monthly aggregated measurement samples within areas of 50 × 50 km2. Globally, the mean precision for the simulated year 2007 is 1.6%, with a standard deviation of 0.7%. At high latitudes, a lower reflectance due to snow and ice is compensated by denser measurements, owing to the orbital pattern. Over key methane source regions such as densely populated areas, boreal and tropical wetlands, or permafrost, our simulations show that the measurement precision will be between 1 and 2%.
- Published
- 2014
- Full Text
- View/download PDF
33. A Case Study on the Effects of Heterogeneous Soil Moisture on Mesoscale Boundary-Layer Structure in the Southern Great Plains, U.S.A. Part I: Simple Prognostic Model
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Desai, Ankur R., Davis, Kenneth J., Senff, Christoph J., Ismail, Syed, Browell, Edward V., Stauffer, David R., and Reen, Brian P.
- Published
- 2006
- Full Text
- View/download PDF
34. Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar
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Abshire, James B, Ramanathan, Anand, Riris, Haris, Mao, Jianping, Allan, Graham R, Hasselbrack, William E, Weaver, Clark J, and Browell, Edward V
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Earth Resources And Remote Sensing - Abstract
We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5-6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s) matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were <1.4 ppm for flight measurement altitudes >6 km.
- Published
- 2013
- Full Text
- View/download PDF
35. Analysis of laser fluorosensor systems for remote algae detection and quantification / Edward V. Brownell.
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Browell, Edward V., Langley Research Center, MBLWHOI Library, Browell, Edward V., and Langley Research Center
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Algae ,Equipment and supplies ,Evaluation ,Lasers in biology ,Measurement ,Remote sensing ,System analysis - Published
- 1977
36. Impact of CAMEX-4 datasets for hurricane forecasts using a global model
- Author
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Kamineni, Rupa, Krishnamurti, T.N., Pattnaik, S., Browell, Edward V., Ismail, Syed, and Ferrare, Richard A.
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Hurricanes -- Research ,Hurricanes -- Forecasts and trends ,Weather forecasting -- Research ,Market trend/market analysis ,Earth sciences ,Science and technology - Abstract
This study explores the impact on hurricane data assimilation and forecasts from the use of dropsondes and remotely sensed moisture profiles from the airborne Lidar Atmospheric Sensing Experiment (LASE) system. It is shown here that the use of these additional datasets, more than those from the conventional world weather watch, has a positive impact on hurricane predictions. The forecast tracks and intensity from the experiments show a marked improvement compared to the control experiment in which such datasets were excluded. A study of the moisture budget in these hurricanes showed enhanced evaporation and precipitation over the storm area. This resulted in these datasets making a large impact on the estimate of mass convergence and moisture fluxes, which were much smaller in the control runs. Overall this study points to the importance of high vertical resolution humidity datasets for improved model results. It is noted that the forecast impact from the moisture-profiling datasets for some of the storms is even larger than the impact from the use of dropwindsonde-based winds.
- Published
- 2006
37. Analysis of laser fluorosensor systems for remote algae detection and quantification
- Author
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Browell, Edward V., Langley Research Center, MBLWHOI Library, Browell, Edward V., and Langley Research Center
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Algae ,Equipment and supplies ,Evaluation ,Lasers in biology ,Measurement ,Remote sensing ,System analysis
38. Atmospheric CO2 Column Measurements with an Airborne Intensity-Modulated Continuous-Wave 1.57-micron Fiber Laser Lidar
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Dobler, Jeremy T, Harrison, F. Wallace, Browell, Edward V, Lin, Bing, McGregor, Doug, Kooi, Susan, Choi, Yonghoon, and Ismail, Syed
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Meteorology And Climatology - Abstract
The 2007 National Research Council (NRC) Decadal Survey on Earth Science and Applications from Space recommended Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) as a mid-term, Tier II, NASA space mission. ITT Exelis, formerly ITT Corp., and NASA Langley Research Center have been working together since 2004 to develop and demonstrate a prototype Laser Absorption Spectrometer for making high-precision, column CO2 mixing ratio measurements needed for the ASCENDS mission. This instrument, called the Multifunctional Fiber Laser Lidar (MFLL), operates in an intensity-modulated, continuous-wave mode in the 1.57- micron CO2 absorption band. Flight experiments have been conducted with the MFLL on a Lear-25, UC-12, and DC-8 aircraft over a variety of different surfaces and under a wide range of atmospheric conditions. Very high-precision CO2 column measurements resulting from high signal-to-noise (great than 1300) column optical depth measurements for a 10-s (approximately 1 km) averaging interval have been achieved. In situ measurements of atmospheric CO2 profiles were used to derive the expected CO2 column values, and when compared to the MFLL measurements over desert and vegetated surfaces, the MFLL measurements were found to agree with the in situ-derived CO2 columns to within an average of 0.17% or approximately 0.65 ppmv with a standard deviation of 0.44% or approximately 1.7 ppmv. Initial results demonstrating ranging capability using a swept modulation technique are also presented.
- Published
- 2013
39. Observations of Greenhouse Gas Changes Across Summer Frontal Boundaries in the Eastern United States
- Author
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Pal, Sandip, primary, Davis, Kenneth J., additional, Lauvaux, Thomas, additional, Browell, Edward V., additional, Gaudet, Brian J., additional, Stauffer, David R., additional, Obland, Michael D., additional, Choi, Yonghoon, additional, DiGangi, Josh P., additional, Feng, Sha, additional, Lin, Bing, additional, Miles, Natasha L., additional, Pauly, Rebecca M., additional, Richardson, Scott J., additional, and Zhang, Fuqing, additional
- Published
- 2020
- Full Text
- View/download PDF
40. NASA ASCENDS Mission to Measure Atmospheric CO2 from Space: A Status Report
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Abshire, James B, Jucks, Kenneth W, Browell, Edward V, Spiers, Gary, and Mao, Jianping
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Earth Resources And Remote Sensing - Published
- 2012
41. Observing System Simulations for the NASA ASCENDS Lidar CO2 Mission Concept: Substantiating Science Measurement Requirements
- Author
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Kawa, Stephan R, Baker, David Frank, Schuh, Andrew E, Abshire, James Brice, Browell, Edward V, and Michalak, Anna M
- Subjects
Meteorology And Climatology - Abstract
The NASA ASCENDS mission (Active Sensing of Carbon Emissions, Nights, Days, and Seasons) is envisioned as the next generation of dedicated, space-based CO2 observing systems, currently planned for launch in about the year 2022. Recommended by the US National Academy of Sciences Decadal Survey, active (lidar) sensing of CO2 from space has several potentially significant advantages, in comparison to current and planned passive CO2 instruments, that promise to advance CO2 measurement capability and carbon cycle understanding into the next decade. Assessment and testing of possible lidar instrument technologies indicates that such sensors are more than feasible, however, the measurement precision and accuracy requirements remain at unprecedented levels of stringency. It is, therefore, important to quantitatively and consistently evaluate the measurement capabilities and requirements for the prospective active system in the context of advancing our knowledge of carbon flux distributions and their dependence on underlying physical processes. This amounts to establishing minimum requirements for precision, relative accuracy, spatial/temporal coverage and resolution, vertical information content, interferences, and possibly the tradeoffs among these parameters, while at the same time framing a mission that can be implemented within a constrained budget. Here, we present results of observing system simulation studies, commissioned by the ASCENDS Science Requirements Definition Team, for a range of possible mission implementation options that are intended to substantiate science measurement requirements for a laser-based CO2 space instrument.
- Published
- 2012
42. Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 Airborne Campaign
- Author
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Abshire, James B, Riris, Haris, Allan, Graham R, Ramanathan, Anand, Hasselbrack, William E, Mao, Jianping, Weaver, Clark, and Browell, Edward V
- Subjects
Geophysics - Abstract
We have previously demonstrated an efficient pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. Our team participated in the 2010 ASCENDS airborne campaigns we flew airborne version of the CO2 and O2 lidar on the NASA DC-8. The CO2 lidar measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line using 250 mW average laser power, 30 wavelength samples per scan and 300 scans per second. Most flights had 5-6 altitude steps to greater than 12 km, and clear CO2 line shapes were observed at all altitudes. Our post-flight analysis estimated the Iidar range and pulse energies at each wavelength every second. We then solved for the best-fit CO2 absorption line shape, and calculated the Differential Optical Depth (DOD) at the line peak. We compared these to CO2 DODs calculated from spectroscopy based on HITRAN 2008 and the conditions from airborne in-situ readings. Analysis of the 2010 measurements over the Pacific Ocean and Lamont OK shows the expected -linear change of the peak DOD with altitude. For measurements at altitudes greater than 6 km the random errors were approximately 0.3 ppm for 80 sec averaging times. After the 2010 flights we improved the airborne lidar's scan uniformity, calibration and receiver sensitivity. Our team participated in the seven ASCENDS science flights during late July and August 2011. These flights were made over a wide variety of surface and cloud conditions near the US, including over the central valley of California, over several mountain ranges, over both broken and solid stratus cloud deck over the Pacific Ocean, snow patches on mountain tops, over thin and broken clouds above the US Southwest and Iowa, and over forests near the WLEF tower in Wisconsin. Analyses show the retrievals of lidar range and CO2 column absorption, as wen as estimates of CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds and to stratus cloud tops. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption profile (averaged for 50 sec) matched the predicted profile to better than 1% RMS error for all flight altitudes. For 1 & 10 second averaging, the scatter in the retrievals was limited by signal shot noise (i.e. the sigual photon count). Analysis to date shows the decrease in CO2 due to vegetation when flying easterward over the Great Plains as well as the increase in CO2 concentration in the vicinity ofthe coal-fired power plant in New Mexico. Examples of these and other results will be presented.
- Published
- 2012
43. Pulsed Airborne Lidar Measurements of C02 Column Absorption
- Author
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Abshire, James B, Riris, Haris, Allan, Graham R, Weaver, Clark J, Mao, Jianping, Sun, Xiaoli, Hasselbrack, William E, Rodriquez, Michael, and Browell, Edward V
- Subjects
Optics - Abstract
We report on airborne lidar measurements of atmospheric CO2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show approx.1 ppm random errors for 8-10 km altitudes and approx.30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows approx. 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes> 6 km.
- Published
- 2011
44. Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes
- Author
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Abshire, James B, Weaver, Clark J, Riris, Haris, Mao, Jianping, Sun, Xiaoli, Allan, Graham R, Hasselbrack, William, and Browell, Edward V
- Subjects
Communications And Radar - Abstract
We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, and in-situ measurements were made using its CO2 sensor and radiosondes. We have conducted an analysis of the ranging and IPDA lidar measurements from these four flights. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We used a cross-correlation approach to process the laser echo records. This was used to estimate the range to the scattering surface, to define the edges of the laser pulses and to determine echo pulse energy at each wavelength. We used a minimum mean square approach to fit an instrument response function and to solve for the best-fit CO2 absorption line shape. We then calculated the differential optical depth (DOD) of the fitted CO2 line. We computed its statistics at the various altitude steps, and compare them to the DODs calculated from spectroscopy based on HITRAN 2008 and the column conditions calculated from the airborne in-situ readings. The results show the lidar and in-situ measurements have very similar DOD change with altitude and greater than 10 segments per flight where the scatter in the lidar measurements are less than or equal to 1ppm. We also present the results from subsequent CO2 column absorption measurements, which were made with stronger detected signals during three flights on the NASA DC-8 over the southwestern US in during July 2010.
- Published
- 2011
45. Development of the Global Ozone Lidar Demonstrator (GOLD) Instrument for Deployment on the NASA Global Hawk
- Author
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Hair, Jonathan W, Browell, Edward V, McGee, Thomas, Butler, Carolyn, Fenn, Marta, Os,ao;. Sued, Notari, Anthony, Collins, James, Cleckner, Craig, and Hostetler, Chris
- Subjects
Cybernetics, Artificial Intelligence And Robotics - Abstract
A compact ozone (O3) and aerosol lidar system is being developed for conducting global atmospheric investigations from the NASA Global Hawk Uninhabited Aerial Vehicle (UAV) and for enabling the development and test of a space-based O3 and aerosol lidar. GOLD incorporates advanced technologies and designs to produce a compact, autonomously operating O3 and aerosol Differential Absorption Lidar (DIAL) system for a UAV platform. The GOLD system leverages advanced Nd:YAG and optical parametric oscillator laser technologies and receiver optics, detectors, and electronics. Significant progress has been made toward the development of the GOLD system, and this paper describes the objectives of this program, basic design of the GOLD system, and results from initial ground-based atmospheric tests.
- Published
- 2010
46. Convective and Wave Signatures in Ozone Profiles Over the Equatorial Americas: Views from TC4 (2007) and SHADOZ
- Author
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Thompson, Anne M, MacFarlane, Alaina M, Morris, Gary A, Yorks, John E, Miller, Sonya K, Taubman, Brett F, Verver, Ge, Voemel, Holger, Avery, Melody A, Hair, Johnathan W, Diskin, Glenn S, Browell, Edward V, Canossa, Jessica Valverde, Kucsera, Tom L, Klich, Christopher A, and Hlavka, Dennis L
- Subjects
Meteorology And Climatology - Abstract
During the months of July-August 2007 NASA conducted a research campaign called the Tropical Composition, Clouds and Climate Coupling (TC4) experiment. Vertical profiles of ozone were measured daily using an instrument known as an ozonesonde, which is attached to a weather balloon and launch to altitudes in excess of 30 km. These ozone profiles were measured over coastal Las Tablas, Panama (7.8N, 80W) and several times per week at Alajuela, Costa Rica (ION, 84W). Meteorological systems in the form of waves, detected most prominently in 100- 300 in thick ozone layer in the tropical tropopause layer, occurred in 50% (Las Tablas) and 40% (Alajuela) of the soundings. These layers, associated with vertical displacements and classified as gravity waves ("GW," possibly Kelvin waves), occur with similar stricture and frequency over the Paramaribo (5.8N, 55W) and San Cristobal (0.925, 90W) sites of the Southern Hemisphere Additional Ozonesondes (SHADOZ) network. The gravity wave labeled layers in individual soundings correspond to cloud outflow as indicated by the tracers measured from the NASA DC-8 and other aircraft data, confirming convective initiation of equatorial waves. Layers representing quasi-horizontal displacements, referred to as Rossby waves, are robust features in soundings from 23 July to 5 August. The features associated with Rossby waves correspond to extra-tropical influence, possibly stratospheric, and sometimes to pollution transport. Comparison of Las Tablas and Alajuela ozone budgets with 1999-2007 Paramaribo and San Cristobal soundings shows that TC4 is typical of climatology for the equatorial Americas. Overall during TC4, convection and associated meteorological waves appear to dominate ozone transport in the tropical tropopause layer.
- Published
- 2009
- Full Text
- View/download PDF
47. Summertime Influence of Asian Pollution in the Free Troposphere over North America
- Author
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Liang, Q, Jaegle, Lyatt, Hudman, Rynda C, Turquety, Solene, Jacob, Daniel J, Avery, Melody A, Blake, Donald R, Browell, Edward V, Sachse, Glen W, Brune, W. H, Ren, Xinrong, Clarke, A, Cohen, R, Dibb, Jack, Fried, Alan, Fuelberg, Henry, Porter, M, Heikes, Brian, Huey, Greg, Singh, H. B, and Wennberg, Paul
- Subjects
Environment Pollution - Abstract
We analyze aircraft observations obtained during INTEX-A (1 July 14 - August 2004) to examine the summertime influence of Asian pollution in the free troposphere over North America. By applying correlation analysis and Principal Component Analysis (PCA) to the observations between 6-12 km, we find dominant influences from recent convection and lightning (13 percent of observations), Asia (7 percent), the lower stratosphere (7 percent), and boreal forest fires (2 percent), with the remaining 71 percent assigned to background. Asian airmasses are marked by high levels of CO, O3, HCN, PAN, acetylene, benzene, methanol, and SO4(2-). The partitioning of reactive nitrogen species in the Asian plumes is dominated by peroxyacetyl nitrate (PAN) (approximately 600 pptv), with varying NO(x)/HNO3 ratios in individual plumes consistent with different plumes ages ranging from 3 to 9 days. Export of Asian pollution in warm conveyor belts of mid-latitude cyclones, deep convection, and lifting in typhoons all contributed to the five major Asian pollution plumes. Compared to past measurement campaigns of Asian outflow during spring, INTEX-A observations display unique characteristics: lower levels of anthropogenic pollutants (CO, propane, ethane, benzene) due to their shorter summer lifetimes; higher levels of biogenic tracers (methanol and acetone) because of a more active biosphere; as well as higher levels of PAN, NO(x), HNO3, and O3 (more active photochemistry possibly enhanced by injection of lightning NO(x)). The high delta O3/delta CO ratio (0.76 mol mol(exp -1)) of Asian plumes during INTEX-A is due to a combination of strong photochemical production and mixing with stratospheric air along isentropic surfaces. The GEOS-Chem global chemical transport model captures the timing and location of the Asian plumes remarkably well. However, it significantly underestimates the magnitude of the enhancements.
- Published
- 2007
48. Denitrification in the Arctic mid-winter 2004/2005 observed by airborne submillimeter radiometry
- Author
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Kleinbohl, Armin, Bremer, Holger, Kullmann, Harry, Kuttippurath, Jayanarayanan, Browell, Edward V, Canty, Timothy, Salawitch, Ross J, Toon, Geoffrey C, and Nothol, Justus
- Subjects
Geophysics - Abstract
We present measurements of unusually low mixing ratios of HNO3 in the exceptionally cold Arctic vortex of late-January and early-February 2005. The measurements were obtained by the airborne submillimeter radiometer ASUR during the polar aura validation experiment (PAVE). The distribution of HNO3 inside the vortex reaches minima below 4 ppbv around 22 km altitude and maxima above 13 ppbv around 16 km altitude, with a considerable spatial variability.
- Published
- 2005
49. Impact of CAMEX-4 Data Sets for Hurricane Forecasts using a Global Model
- Author
-
Kamineni, Rupa, Krishnamurti, T. N, Pattnaik, S, Browell, Edward V, Ismail, Syed, and Ferrare, Richard A
- Subjects
Meteorology And Climatology - Abstract
This study explores the impact on hurricane data assimilation and forecasts from the use of dropsondes and remote-sensed moisture profiles from the airborne Lidar Atmospheric Sensing Experiment (LASE) system. We show that the use of these additional data sets, above those from the conventional world weather watch, has a positive impact on hurricane predictions. The forecast tracks and intensity from the experiments show a marked improvement compared to the control experiment where such data sets were excluded. A study of the moisture budget in these hurricanes showed enhanced evaporation and precipitation over the storm area. This resulted in these data sets making a large impact on the estimate of mass convergence and moisture fluxes, which were much smaller in the control runs. Overall this study points to the importance of high vertical resolution humidity data sets for improved model results. We note that the forecast impact from the moisture profiling data sets for some of the storms is even larger than the impact from the use of dropwindsonde based winds.
- Published
- 2005
50. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system
- Author
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Ponsardin, Patrick, Higdon, Noah S., Grossman, Benoist E., and Browell, Edward V.
- Subjects
Optical radar -- Equipment and supplies ,Solid-state lasers -- Evaluation ,Water vapor, Atmospheric -- Measurement ,Astronomy ,Physics - Abstract
A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (>99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 [cm.sup.-1] (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 [cm.sup.-1] (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift ([is approximately equal to] 1.5 h) of less than 0.7 pm in the laboratory. Key words: Alexandrite laser, differential absorption lidar, intracavity etalons, wavelength stabilization, spectral purity.
- Published
- 1994
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