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Midlatitude atmospheric blocking events are important drivers of long-lasting extreme weather conditions at regional to continental scales. However, modern climate models consistently underestimate their frequency of occurrence compared to observations, casting doubt on future projections of climate extremes. Using the prominent and largely underestimated winter blocking events in Europe as a test case, this study first introduces a spatio-temporal approach to study blocking activity based on a clustering technique, allowing to assess models’ ability to simulate both realistic frequencies and locations of blocking events. A sensitivity analysis from an ensemble of 49 simulations from 24 coupled climate models shows that the presence of a mesoscale eddy-permitting ocean model increases the realism of simulated blocking events for almost all types of patterns clustered from observations. This finding is further explained and supported by concomitant reductions in well-documented biases in Gulf Stream and North Atlantic Current positions, as well as in the midlatitude jet stream variability.

Research investigating thermoregulatory energy costs in free-living humans is limited. We determined the total energy expenditure (TEE) of Tuvan pastoralists living in an extreme cold environment and explored the contribution of physical activity and cold-induced thermogenesis. Twelve semi-nomadic pastoralists (47 ± 8 years, 64 ± 8 kg) living under traditional circumstances, in Tuva, south-central Siberia, Russia, were observed during two consecutive 6-day periods in winter. TEE was measured via the doubly labelled water technique. Skin and ambient temperatures, and physical activity were continuously monitored. The outdoor temperature during the observation period was − 27.4 ± 5.4 °C. During the daytime, the participants were exposed to ambient temperatures below 0 °C for 297 ± 131 min/day. The Tuvan pastoralists were more physically active compared to western populations (609 ± 90 min/day of light, moderate, and vigorous physical activity). In addition, TEE was 13.49 ± 1.33 MJ/day (3224 ± 318 kcal/day), which was significantly larger by 17% and 31% than predicted by body mass, and fat-free mass, respectively. Our research suggests the daily cold exposure combined with high levels of physical activity contributed to the elevated TEE. Future research should reconsider the assumption that energy costs due to thermoregulation are negligible in free-living humans.

Climate change is pushing temperatures beyond the thermal tolerance of many species. Whether protected areas (PAs) can serve as climate change refugia for biodiversity has not yet been explored. We find that PAs of natural (seminatural) vegetation effectively cool the land surface temperature, particularly the daily maximum temperature in the tropics, and reduce diurnal and seasonal temperature ranges in boreal and temperate regions, as compared to nonprotected areas that are often disturbed or converted to various land uses. Moreover, protected forests slow the rate of warming more at higher latitudes. The warming rate in protected boreal forests is up to 20% lower than in their surroundings, which is particularly important for species in the boreal where warming is more pronounced. The fact that nonprotected areas with the same type of vegetation as PAs show reduced warming buffer capacity highlights the importance of conservation to stabilize the local climate and safeguard biodiversity.

Land cover and land management change (LCLMC) has been highlighted for its critical role in mitigation scenarios, both in terms of global mitigation and local adaptation. Yet, the climate effect of individual LCLMC options, their dependence on the background climate and the local vs. non-local responses are still poorly understood across different Earth system models (ESMs). Here we simulate the climatic effects of LCLMC using three state-of-the-art ESMs, including the Community Earth System Model (CESM), the Max Planck Institute for Meteorology Earth System Model (MPI-ESM) and the European Consortium Earth System Model (EC-EARTH). We assess the LCLMC effects using the following four idealized experiments: (i) a fully afforested world, (ii) a world fully covered by cropland, (ii) a fully afforested world with extensive wood harvesting and (iv) a full-cropland world with extensive irrigation. In these idealized sensitivity experiments, performed under present-day climate conditions, the effects of the different LCLMC strategies represent an upper bound for the potential of global mitigation and local adaptation. To disentangle the local and non-local effects from the LCLMC, a checkerboard-like LCLMC perturbation, i.e. alternating grid boxes with and without LCLMC, is applied. The local effects of deforestation on surface temperature are largely consistent across the ESMs and the observations, with a cooling in boreal latitudes and a warming in the tropics. However, the energy balance components driving the change in surface temperature show less consistency across the ESMs and the observations. Additionally, some biases exist in specific ESMs, such as a strong albedo response in CESM mid-latitudes and a soil-thawing-driven warming in boreal latitudes in EC-EARTH. The non-local effects on surface temperature are broadly consistent across ESMs for afforestation, though larger model uncertainty exists for cropland expansion. Irrigation clearly induces a cooling effect; however, the ESMs disagree whether these are mainly local or non-local effects. Wood harvesting is found to have no discernible biogeophysical effects on climate. Overall, our results underline the potential of ensemble simulations to inform decision making regarding future climate consequences of land-based mitigation and adaptation strategies., Earth System Dynamics, 14 (3), ISSN:2190-4987, ISSN:2190-4979

For short-lived climate forcers such as black carbon (BC), the atmospheric concentrations, radiative forcing (RF), and, ultimately, the subsequent effects on climate, depend on the location and timing of the emissions. Here, we employ the NorESM1-Happi version of the Norwegian Earth System Model to systematically study how the RF associated with BC emissions depends on the latitude, longitude, and seasonality of the emissions. The model aerosol scheme is run in an offline mode to allow for an essentially noise-free evaluation of the RF associated with even minor changes in emissions. A total of 960 experiments were run to evaluate the BC direct RF (dirRF) and the RF associated with BC in snow/ice (snowRF) for emissions in 192 latitude–longitude boxes covering the globe, both for seasonally uniform emissions and for emissions in each of the four seasons separately. We also calculate a rough estimate of the global temperature response to regional emissions and provide a Fortran-based tool to facilitate the further use of our results. Overall, the results demonstrate that the BC RFs strongly depend on the latitude, longitude, and season of the emissions. In particular, the global mean dirRF normalized by emissions (direct specific forcing; dirSF) depends much more strongly on the emission location than suggested by previous studies that have considered emissions from continental-/subcontinental-scale regions. Even for seasonally uniform emissions, dirSF varies by more than a factor of 10, depending on the emission location. These variations correlate strongly with BC lifetime, which varies from less than 2 to 11 d. BC dirSF is largest for emissions in tropical convective regions and in subtropical and midlatitude continents in summer, both due to the abundant solar radiation and strong convective transport, which increases BC lifetime and the amount of BC above clouds. The dirSF is also relatively large for emissions in high-albedo, high-latitude regions such as Antarctica and Greenland. The dependence of snow specific forcing (snowSF) on the emission location is even larger. While BC emissions originating from most low-latitude regions result in negligible snowSF, the maxima of snowSF for emissions in polar regions greatly exceed the largest values of dirSF for low-latitude emissions. The large magnitude of snowSF for high-latitude BC emissions suggests that, for a given mass of BC emitted, the climate impacts are also largest for high-latitude emissions. The additivity of the RFs resulting from BC emissions in different regions and seasons is also investigated. It is found that dirRF is almost additive for current-day emissions, so that summing the RFs computed for individual regions/seasons without considering BC emissions from elsewhere overestimates dirRF by less than 10 %. For snowRF, the overestimate is somewhat larger, at ∼ 20 %.

Urban areas are particularly vulnerable to climate change due to the Urban Heat Island (UHI) effect, which can be mitigated by urban vegetation through shading and evapotranspiration. Nevertheless, there is still a lack of spatially explicit information on the cooling capacity of green infrastructure for most Latin American cities. In this study, we employed Land Surface Temperature (LST) of the Neotropical Mexican city of Xalapa to (1) analyze its Surface UHI (SUHI) compared to its peri and extra-urban areas, (2) to assess the cooling capacity of urban green spaces larger than 1ha, and (3) to evaluate the role of green spaces’ size, shape and their surrounding tree cover percentage (Tc) on green spaces cooling range. We evaluated the cooling range of green spaces and their relationships with green spaces metrics and Tc via a linear mixed-effect model and identify threshold values for the variables at 25, 50, 100, and 200m from the borders of green spaces through Classification and Regression Trees. Xalapa exhibits a SUHI of 1.70 °C compared to its peri-urban area and 4.95 °C to the extra-urban area. Green spaces > 2ha mitigated heat at ~2 °C and the cooling range was influenced by the size of green spaces ≥ 2.8ha and Tc > 21% at 50m and only by Tc surrounding the green spaces at 100m and 200m. This shows that the size threshold of urban green spaces should be complemented with the presence of Tc starting at least 50m to maximize the cooling capacity provided by the green infrastructure. Planning agendas should account for the interaction between the size of green spaces and the cumulative cooling effect of scattered vegetation inside urban areas towards compact green cities to cope with urban warming.

Infrared thermography technology has improved dramatically in recent years and is gaining renewed interest in the medical community for applications in skin tissue identification applications. However, there is still a need for an optimized measurement setup and protocol to obtain the most appropriate images for decision making and further processing. Nowadays, various cooling methods, measurement setups and cameras are used, but a general optimized cooling and measurement protocol has not been defined yet. In this literature review, an overview of different measurement setups, thermal excitation techniques and infrared camera equipment is given. It is possible to improve thermal images of skin lesions by choosing an appropriate cooling method, infrared camera and optimized measurement setup.

Empirical evidence demonstrates that lakes and reservoirs are warming across the globe. Consequently, there is an increased need to project future changes in lake thermal structure and resulting changes in lake biogeochemistry in order to plan for the likely impacts. Previous studies of the impacts of climate change on lakes have often relied on a single model forced with limited scenario-driven projections of future climate for a relatively small number of lakes. As a result, our understanding of the effects of climate change on lakes is fragmentary, based on scattered studies using different data sources and modelling protocols, and mainly focused on individual lakes or lake regions. This has precluded identification of the main impacts of climate change on lakes at global and regional scales and has likely contributed to the lack of lake water quality considerations in policy-relevant documents, such as the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC). Here, we describe a simulation protocol developed by the Lake Sector of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) for simulating climate change impacts on lakes using an ensemble of lake models and climate change scenarios for ISIMIP phases 2 and 3. The protocol prescribes lake simulations driven by climate forcing from gridded observations and different Earth system models under various representative greenhouse gas concentration pathways (RCPs), all consistently bias-corrected on a 0.5∘ × 0.5∘ global grid. In ISIMIP phase 2, 11 lake models were forced with these data to project the thermal structure of 62 well-studied lakes where data were available for calibration under historical conditions, and using uncalibrated models for 17 500 lakes defined for all global grid cells containing lakes. In ISIMIP phase 3, this approach was expanded to consider more lakes, more models, and more processes. The ISIMIP Lake Sector is the largest international effort to project future water temperature, thermal structure, and ice phenology of lakes at local and global scales and paves the way for future simulations of the impacts of climate change on water quality and biogeochemistry in lakes.

Many remote sensing-based evapotranspiration (RSBET) algorithms have been proposed in the past decades and evaluated using flux tower data, mainly over North America and Europe. Model evaluation across South America has been done locally or using only a single algorithm at a time. Here, we provide the first evaluation of multiple RSBET models, at a daily scale, across a wide variety of biomes, climate zones, and land uses in South America. We used meteorological data from 25 flux towers to force four RSBET models: Priestley–Taylor Jet Propulsion Laboratory (PT-JPL), Global Land Evaporation Amsterdam Model (GLEAM), Penman–Monteith Mu model (PM-MOD), and Penman–Monteith Nagler model (PME-VI). ET was predicted satisfactorily by all four models, with correlations consistently higher (R2 > 0.6) for GLEAM and PT-JPL, and PM-MOD and PM-VI presenting overall better responses in terms of percent bias (- 10

For climate-change impact studies at the catchment scale, meteorological variables are typically extracted from ensem-ble simulations provided by global and regional climate models, which are then downscaled and bias-adjusted for eachstudy site. For bias adjustment, different statistical methods that re-scaleclimate model outputs have been suggested inthe scientific literature. They range from simple univariate methods that adjust each meteorological variable individ-ually, to more complex and more demanding multivariate methods that take existing relationships between meteoro-logical variables into consideration. Over the past decade, several attempts have been made to evaluate such methodsin various regions. There is, however, still no guidance for choosing appropriate bias adjustment methods for a study athand. In particular, the question whether the benefits of potentially improved adjustments outweigh the cost of in-creased complexity, remains unanswered.This paper presents a comprehensive evaluation of the performance of two commonly used univariate and two multi-variate bias adjustment methods in reproducing numerous univariate, multivariate and temporal features of precipita-tion and temperature series in different catchments in Sweden. The paper culminates in a discussion on trade-offs between the potential benefits (i.e., skills and added value) and disadvantages (complexity and computational de-mand) of each method to offer plausible, defensible and actionable insights from the standpoint of climate-change im-pact studies in high latitudes.We concluded that all selected bias adjustment methods generally improved the raw climate model simulations, but that not a single method consistently outperformed the other methods. There were, however, differences in the methods' performance for particular statistical features, indicating that other practical aspects such as computationaltime and heavy theoretical requirements should also be taken into consideration when choosing an appropriate biasadjustment method

Framed within the Copernicus Climate Change Service (C3S) of the European Commission, the European Centre for Medium-Range Weather Forecasts (ECMWF) is producing an enhanced global dataset for the land component of the fifth generation of European ReAnalysis (ERA5), hereafter referred to as ERA5-Land. Once completed, the period covered will span from 1950 to the present, with continuous updates to support land monitoring applications. ERA5-Land describes the evolution of the water and energy cycles over land in a consistent manner over the production period, which, among others, could be used to analyse trends and anomalies. This is achieved through global high-resolution numerical integrations of the ECMWF land surface model driven by the downscaled meteorological forcing from the ERA5 climate reanalysis, including an elevation correction for the thermodynamic near-surface state. ERA5-Land shares with ERA5 most of the parameterizations that guarantees the use of the state-of-the-art land surface modelling applied to numerical weather prediction (NWP) models. A main advantage of ERA5-Land compared to ERA5 and the older ERA-Interim is the horizontal resolution, which is enhanced globally to 9 km compared to 31 km (ERA5) or 80 km (ERA-Interim), whereas the temporal resolution is hourly as in ERA5. Evaluation against independent in situ observations and global model or satellite-based reference datasets shows the added value of ERA5-Land in the description of the hydrological cycle, in particular with enhanced soil moisture and lake description, and an overall better agreement of river discharge estimations with available observations. However, ERA5-Land snow depth fields present a mixed performance when compared to those of ERA5, depending on geographical location and altitude. The description of the energy cycle shows comparable results with ERA5. Nevertheless, ERA5-Land reduces the global averaged root mean square error of the skin temperature, taking as reference MODIS data, mainly due to the contribution of coastal points where spatial resolution is important. Since January 2020, the ERA5-Land period available has extended from January 1981 to the near present, with a 2- to 3-month delay with respect to real time. The segment prior to 1981 is in production, aiming for a release of the whole dataset in summer/autumn 2021. The high spatial and temporal resolution of ERA5-Land, its extended period, and the consistency of the fields produced makes it a valuable dataset to support hydrological studies, to initialize NWP and climate models, and to support diverse applications dealing with water resource, land, and environmental management. The full ERA5-Land hourly (Muñoz-Sabater, 2019a) and monthly (Muñoz-Sabater, 2019b) averaged datasets presented in this paper are available through the C3S Climate Data Store at https://doi.org/10.24381/cds.e2161bac and https://doi.org/10.24381/cds.68d2bb30, respectively.

Quantifying the efficacy of different climate forcings is important for understanding the real‐world climate sensitivity. This study presents a systematic multimodel analysis of different climate driver efficacies using simulations from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP). Efficacies calculated from instantaneous radiative forcing deviate considerably from unity across forcing agents and models. Effective radiative forcing (ERF) is a better predictor of global mean near‐surface air temperature (GSAT) change. Efficacies are closest to one when ERF is computed using fixed sea surface temperature experiments and adjusted for land surface temperature changes using radiative kernels. Multimodel mean efficacies based on ERF are close to one for global perturbations of methane, sulfate, black carbon, and insolation, but there is notable intermodel spread. We do not find robust evidence that the geographic location of sulfate aerosol affects its efficacy. GSAT is found to respond more slowly to aerosol forcing than CO2 in the early stages of simulations. Despite these differences, we find that there is no evidence for an efficacy effect on historical GSAT trend estimates based on simulations with an impulse response model, nor on the resulting estimates of climate sensitivity derived from the historical period. However, the considerable intermodel spread in the computed efficacies means that we cannot rule out an efficacy‐induced bias of ±0.4 K in equilibrium climate sensitivity to CO2 doubling when estimated using the historical GSAT trend., Key Points Multimodel mean efficacies computed using effective radiative forcing are close to one for major anthropogenic drivers, but there is notable intermodel spreadSurface temperature‐driven radiative feedbacks are generally not constant through time across forcing experimentsPDRMIP results suggest that the efficacy impact on equilibrium climate sensitivity derived from the historical period is limited to ±0.4 °C or better

Satellite Earth observation has led to the creation of global climate data records of many important environmental and climatic variables. These come in the form of multivariate time series with different spatial and temporal resolutions. Data of this kind provide new means to further unravel the influence of climate on vegetation dynamics. However, as advocated in this article, commonly used statistical methods are often too simplistic to represent complex climate–vegetation relationships due to linearity assumptions. Therefore, as an extension of linear Granger-causality analysis, we present a novel non-linear framework consisting of several components, such as data collection from various databases, time series decomposition techniques, feature construction methods, and predictive modelling by means of random forests. Experimental results on global data sets indicate that, with this framework, it is possible to detect non-linear patterns that are much less visible with traditional Granger-causality methods. In addition, we discuss extensive experimental results that highlight the importance of considering non-linear aspects of climate–vegetation dynamics.

High-quality road condition forecasts are a prerequisite for road authorities to ensure wintertime road safety. Harsh winter conditions can cause problems for traffic not only in countries where snowy winters are common but also in regions where the temperature drops below the freezing point occasionally. This study reports on the evaluation of the Royal Netherlands Meteorological Institute’s (KNMI) new road weather forecasting model by comparing it with the Finnish Meteorological Institute’s (FMI) road weather model, both run for 321 Dutch road weather stations, four times daily (0300, 0900, 1500, and 2100 UTC) during the test period, 15 January–28 February 2015. Road surface temperature forecasts by both models were evaluated against observations. The KNMI model produced slightly more accurate forecasts than the FMI model. The main reason for the difference is probably due to the optimization of the physical properties of the KNMI model for the Netherlands, whereas the FMI model is designed for quite different Finnish wintertime meteorological conditions. However, in general the road surface temperature forecasts were of quite comparable quality.

Paleoclimate reconstructions suggest that the complex variability within the Greenland stadial 1 (GS-1) over western Europe was governed by coupled ocean and atmospheric changes. However, few works from the North Atlantic mid-latitudes document both the GS-1 onset and its termination, which are often considered as single abrupt transition events. Here, we present a direct comparison between marine (alkenone-based sea surface temperatures) and terrestrial (pollen) data, at very high resolution (28 years mean), from the southwestern Iberian shelf record D13882. Our results reveal a rather complex climatic period with internally changing conditions. The GS-1 onset (GS-1a: 12890-12720 yr BP) is marked by a progressive cooling and drying GS-1b (12720-12390 yr BP) is the coldest and driest phase; GS-1c (12390-12030 yr BP) is marked by a progressive warming and increase in moisture conditions; GS-1 termination (GS-1d: 12030-11770 yr BP) is marked by rapid switches between cool wet, cold dry and cool wet conditions. Although hydroclimate response was very unsteady throughout the GS-1 and in particular during its termination phase, the persistence of an open temperate and Mediterranean forest in southwestern Iberia during the entire episode suggests that at least some moisture was delivered via the Westerlies. We propose coupled ocean and atmospheric mechanisms to reproduce these scenario. Changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) as well as variations in the North Atlantic sea-ice growth have favoured the displacement of the polar jet stream's latitudinal position and contributed to a complex spatial pattern and strength of the Westerlies across western Europe. (C) 2019 Elsevier Ltd. All rights reserved. FCT - Foundation for Science and TechnologyPortuguese Foundation for Science and Technology [PTDC/AAC-CLI/100157/2008, IF/01489/2015, UID/multi/04326/2016, SAICT-45-2017-02, WARM WORLDS: 29897, HOLMODRIVE: 29029] CCMAR BCC grant [Incentivo/MAR/LA00015/2014] IF grant [F/01489/2015, IF/01047/2014] Sandra Gomes PhD Grant [SFRH/BD/128984/2017, SERH/BPD/108600/2015, SFRH/BPD/111433/2015, IPMA-2017-72-BI]

Following earlier regional assessment studies, such as the Assessment of Climate Change for the Baltic Sea Basin and the North Sea Region Climate Change Assessment, knowledge acquired from available literature about future scenario simulations of biogeochemical cycles in the Baltic Sea and their uncertainties is assessed. The identification and reduction of uncertainties of scenario simulations are issues for marine management. For instance, it is important to know whether nutrient load abatement will meet its objectives of restored water quality status in future climate or whether additional measures are required. However, uncertainties are large and their sources need to be understood to draw conclusions about the effectiveness of measures. The assessment of sources of uncertainties in projections of biogeochemical cycles based on authors' own expert judgment suggests that the biggest uncertainties are caused by (1) unknown current and future bioavailable nutrient loads from land and atmosphere, (2) the experimental setup (including the spin up strategy), (3) differences between the projections of global and regional climate models, in particular, with respect to the global mean sea level rise and regional water cycle, (4) differing model-specific responses of the simulated biogeochemical cycles to long-term changes in external nutrient loads and climate of the Baltic Sea region, and (5) unknown future greenhouse gas emissions. Regular assessments of the models' skill (or quality compared to observations) for the Baltic Sea region and the spread in scenario simulations (differences among projected changes) as well as improvement of dynamical downscaling methods are recommended.

Considerable ambiguity remains over the extent and nature of millennial/centennial-scale climate instability during the Last Interglacial (LIG). Here we analyse marine and terrestrial proxies from a deep-sea sediment sequence on the Portuguese Margin and combine results with an intensively dated Italian speleothem record and climate-model experiments. The strongest expression of climate variability occurred during the transitions into and out of the LIG. Our records also document a series of multi-centennial intra-interglacial arid events in southern Europe, coherent with cold water-mass expansions in the North Atlantic. The spatial and temporal fingerprints of these changes indicate a reorganization of ocean surface circulation, consistent with low-intensity disruptions of the Atlantic meridional overturning circulation (AMOC). The amplitude of this LIG variability is greater than that observed in Holocene records. Episodic Greenland ice melt and runoff as a result of excess warmth may have contributed to AMOC weakening and increased climate instability throughout the LIG. © 2018, The Author(s)., We thank A. Scrivner and C. Walmsley for assistance with foraminifer sample preparation and J. Rolfe and I. Mather for technical assistance with stable isotope measurements, M. Maslin and D. Thornalley for comments on an earlier version of the manuscript, A. Carlson and E. Galaasen for discussions and E. Galaasen and N. Irvali for providing the MD03-2664 data. V.M., K.R., L.C.S. and P.C.T. acknowledge support for the MD01-2444 study from UK-NERC project NE/G00756X/1 (to P.C.T. and L.C.S.). R.N.D., L.C.S., E.R., G.Z. and P.C.T. acknowledge support from Australian Research Council grant DP160102969 (to R.N.D.). L.M. acknowledges support from the Australian Research Council grant DE150100107. A.S.T. and J.H. are supported by the Australian Research Council (ARC). The numerical experiments were undertaken on the NCI National Facility at the ANU, Australia. B.M. acknowledges support from the CSIC-Ramón y Cajal postdoctoral programme RYC-2013-14073. We wish to acknowledge use of the Ferret program for generating the maps in Fig. 6 and Supplementary Figure 6 in this paper. Ferret is a product of NOAA’s Pacific Marine Environmental Laboratory (information is available at http://ferret.pmel.noaa.gov/Ferret/). This paper is a contribution to the PAGES Working Group on Quaternary Interglacials (QUIGS).

A neo-neutron star is a hot neutron star that has just become transparent to neutrinos. In a core collapse supernova or accretion induced collapse of a white dwarf the neo-neutron star phase directly follows the proto-neutron star phase, about 30 to 60 seconds after the initial collapse. It will also be present in a binary neutron star merger in the case the "born-again" hot massive compact star does not immediately collapse into a black hole. Eddington or even super-Eddington luminosities are present for some time. A neo-neutron star produced in a core collapse supernova is not directly observable but the one produced by a binary merger, likely associated with an off-axis short gamma-ray burst, may be observable for some time as well as when produced in the accretion induced collapse of a white dwarf. We present a first step in the study of this neo-neutron star phase in a spherically symmetric configuration, thus neglecting fast rotation, and also neglecting the effect of strong magnetic fields. We put particular emphasis on determining how long the star can sustain a near-Eddington luminosity and also show the importance of positrons and contraction energy during neo-neutron star phase. We finally discuss the observational prospects for neutron star mergers triggered by LIGO and for accretion-induced collapse transients., 23 pages, 19 figures; accepted for publication in ApJ

Changing climate is increasing the amount and intensity of forest stress agents, such as drought, pest insects, and pathogens. Leaf water content, measured here in terms of equivalent water thickness (EWT), is an early indicator of tree stress that provides timely information about the health status of forests. Multispectral terrestrial laser scanning (MS-TLS) measures target geometry and reflectance simultaneously, providing spatially explicit reflectance information at several wavelengths. EWT and leaf internal structure affect leaf reflectance in the shortwave infrared region that can be used to predict EWT with MS-TLS. A second wavelength that is sensitive to leaf internal structure but not affected by EWT can be used to normalize leaf internal effects on the shortwave infrared region and improve the prediction of EWT. Here we investigated the relationship between EWT and laser intensity features using multisensor MS-TLS at 690, 905, and 1,550 nm wavelengths with both drought-treated and Endoconidiophora polonica inoculated Norway spruce seedlings to better understand how MS-TLS measurements can explain variation in EWT. In our study, a normalized ratio of two wavelengths at 905 and 1,550 nm and length of seedling explained 91% of the variation (R-2) in EWT as the respective prediction accuracy for EWT was 0.003 g/cm(2) in greenhouse conditions. The relation between EWT and the normalized ratio of 905 and 1,550 nm wavelengths did not seem sensitive to a decreased point density of the MS-TLS data. Based on our results, different EWTs in Norway spruce seedlings show different spectral responses when measured using MS-TLS. These results can be further used when developing EWT monitoring for improving forest health assessments.

The wall cooling induced by spray impingement is investigated using phosphor thermometry. Thin coatings of zinc oxide (ZnO) phosphor were applied with a transparent chemical binder onto a steel surface. Instantaneous spatially resolved temperatures were determined using the spectral intensity ratio method directly after the injection of UV-grade hexane onto the surface using a commercial gasoline injector. The investigations showed that 2D temperature measurements with high spatial and shot-to-shot precision of, respectively, 0.5 and 0.6 K can be achieved, allowing the accurate resolution of the cooling induced by the spray. The presence of a liquid film over the phosphor coating during measurements showed no noticeable influence on the measured temperatures. However, in some cases a change in the intensity ratio at the spray impingement area, in the form of a permanent “stain”, could be observed after multiple injections. The formation of this stain was less likely with increasing annealing time of the coating as well as lower plate operating temperatures during the injection experiments. Finally, the experimental results indicate a noticeable influence of the thickness of the phosphor coating on the measured spray-induced wall cooling history. Hence, for quantitative analysis, a compromise between coating thickness and measurement accuracy needs to be considered for similar applications where the heat transfer rates are very high.

Coral reefs occupy only similar to 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically induced decline of boron (B) isotopic composition (delta B-11) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published delta B-11 data and our recorded vital effect of coral bleaching on the delta B-11 signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure. Understanding the frequency of bleaching events is also critical for determining the relationship between natural and anthropogenic causes of these events. BMBF/03V0956 National Science Foundation/0920572 SBM Minerva foundation

CHEMTAX was used to assess the relative contribution of the main phytoplankton classes to the total concentration of Chlorophyll a (Chl a) from the waters off SW coast of Portugal. Sampling campaigns were carried out during all seasons from 2008 to 2012, at three stations located 2, 10 and 18 km from the coast. Samples were taken from the surface, mid-Secchi and Secchi depth, for the determination of Chl a and other phytoplanktonic pigments by HPLC. Supporting data were also obtained including dissolved inorganic nutrients, salinity, transparency, temperature and upwelling indices. The CHEMTAX results were also related to microscopy counts and also spectral analysis of absorption of other samples from the same sampling campaigns. The pigment results showed that diatoms dominated from early spring to summer, coinciding with upwelling conditions, while cryptophytes, prymnesiophytes and prasinophytes dominated in autumn and winter, coinciding with seasonal stratification. Although the contribution of cyanobacteria to total Chl a was generally low, there were occasional sampling campaigns where it was exceptionally high, but these appeared not to be related to upwelling. Dinoflagellates and chrysophytes were minority groups although the pigment marker peridinin that was used to distinguish dinoflagellates was not adequate for distinguishing all the members of this group. CHEMTAX was particularly useful for discriminating between the smaller (0–20 μm) classes of the microplankton that could not be easily identified by microscopy., This research was funded by European Space Agency as part of the project “Technical assistance for the validation of MERIS marine products at Portuguese oceanic and coastal sites” (contract n° 21464/08/I-OL). P.C. Goela and S. Cristina are funded by PhD grants from FCT (SFRH/BD/78356/2011 and SFRH/BD/78354/2011, respectively); S. Danchenko is funded by Erasmus Mundus EMJD MACOMA; A. Newton is funded by EU FP7 project DEVOTES (grant agreement no. 308392), www.devotes-project.eu. J. Icely is funded by EU FP7 AQUA_USER (grant agreement no. 607325) www.aqua-users.eu.

Oceanographic features shape the distributional and genetic patterns of marine species by interrupting or promoting connections among populations. Although general patterns commonly arise, distributional ranges and genetic structure are species-specific and do not always comply with the expected trends. By applying a multimarker genetic approach combined with Lagrangian particle simulations (LPS) we tested the hypothesis that oceanographic features along northeastern Atlantic and Mediterranean shores influence dispersal potential and genetic structure of the intertidal mussel Perna perna. Additionally, by performing environmental niche modelling we assessed the potential and realized niche of P. perna along its entire native distributional range and the environmental factors that best explain its realized distribution. Perna perna showed evidence of panmixia across > 4,000 km despite several oceanographic breaking points detected by LPS. This is probably the result of a combination of life history traits, continuous habitat availability and stepping-stone dynamics. Moreover, the niche modelling framework depicted minimum sea surface temperatures (SST) as the major factor shaping P. perna distributional range limits along its native areas. Forthcoming warming SST is expected to further change these limits and allow the species to expand its range polewards though this may be accompanied by retreat from warmer areas. Fundacao para a Ciencia e Tecnologia (FCT-MEC, Portugal) [UID/Multi/04326/2013, IF/01413/2014/CP1217/CT0004]; South African Research Chairs Initiative (SARChI) of the Department of Science and Technology; National Research Foundation; South African National Research Foundation (NRF); Portuguese Fundacao para a Ciencia e Tecnologia (FCT) [SFRH/BPD/85040/2012, SFRH/BPD/111003/2015] info:eu-repo/semantics/publishedVersion

The limited availability of high-resolution continuous archives, insufficient chronological control, and complex hydro-climatic forcing mechanisms lead to many uncertainties in palaeo-hydrological reconstructions for the Western Mediterranean. In this study we present a newly recovered 19.63 m long core from Lake Sidi Ali in the North African Middle Atlas, a transition zone of Atlantic, Western Mediterranean and Saharan air mass trajectories. With a multi-proxy approach based on magnetic susceptibility, carbonate and total organic C content, core-scanning and quantitative XRF, stable isotopes of ostracod shells, charcoal counts, Cedrus pollen abundance, and a first set of diatom data, we reconstruct Western Mediterranean hydro-climatic variability, seasonality and forcing mechanisms during the last 12,000 yr. A robust chronological model based on AMS 14 C dated pollen concentrates supports our high-resolution multi-proxy study. Long-term trends reveal low lake levels at the end of the Younger Dryas, during the mid-Holocene interval 6.6 to 5.4 cal ka BP, and during the last 3000 years. In contrast, lake levels are mostly high during the Early and Mid-Holocene. The record also shows sub-millennial- to centennial-scale decreases in Western Mediterranean winter rain at 11.4, 10.3, 9.2, 8.2, 7.2, 6.6, 6.0, 5.4, 5.0, 4.4, 3.5, 2.9, 2.2, 1.9, 1.7, 1.5, 1.0, 0.7, and 0.2 cal ka BP. Early Holocene winter rain minima are in phase with cooling events and millennial-scale meltwater discharges in the sub-polar North Atlantic. Our proxy parameters do not show so far a clear impact of Saharan air masses on Mediterranean hydro-climate in North Africa. However, a significant hydro-climatic shift at the end of the African Humid Period (∼5 ka) indicates a change in climate forcing mechanisms. The Late Holocene climate variability in the Middle Atlas features a multi-centennial-scale NAO-type pattern, with Atlantic cooling and Western Mediterranean winter rain maxima generally associated with solar minima.

[1] In decadal predictability studies, the subpolar Atlantic stands out as a region of high potential and real predictability. Since local temperature and salinity variations in the region are for a large part controlled by ocean dynamics, skillful predictability of the local ocean dynamics is a prerequisite to obtain multiyear predictability of other variables such as sea surface temperature. In this study, we discuss the predictability of the main ocean current system in the region, the subpolar gyre. From perfect model hindcasts exploiting initial condition information only from realistic ocean observation locations, we find that predictability is increased when Argo subsurface data are included. In our real-world experiments with initialized hindcasts, the observed decline in subpolar gyre strength of the mid-1990s is reproduced well and we find predictability of the subpolar gyre up to 2 years ahead, comparable to the skill of a damped persistence model.

We assess the skill of retrospective multiyear forecasts of North Atlantic ocean characteristics obtained with ocean-atmosphere-sea ice models that are initialized with estimates from the observed ocean state. We show that these multimodel forecasts can skilfully predict surface and subsurface ocean variability with lead times of 2 to 9 years. We focus on assessment of forecasts of major well-observed oceanic phenomena that are thought to be related to the Atlantic meridional overturning circulation (AMOC). Variability in the North Atlantic subpolar gyre, in particular that associated with the Atlantic Multidecadal Oscillation, is skilfully predicted 2-9 years ahead. The fresh water content and heat content in major convection areas such as the Labrador Sea are predictable as well, although individual events are not captured. The skill of these predictions is higher than that of uninitialized coupled model simulations and damped persistence. However, except for heat content in the subpolar gyre, differences between damped persistence and the initialized predictions are not significant. Since atmospheric variability is not predictable on multiyear time scales, initialization of the ocean and oceanic processes likely provide skill. Assessment of relationships of patterns of variability and ocean heat content and fresh water content shows differences among models indicating that model improvement can lead to further improvements of the predictions. The results imply there is scope for skilful predictions of the AMOC.

The Nd isotopic composition (epsilon Nd) of seawater and cold-water coral (CWC) samples from the Gulf of Cadiz and the Alboran Sea, at a depth of 280-827 m were investigated in order to constrain middepth water mass dynamics within the Gulf of Cadiz over the past 40 ka. epsilon Nd of glacial and Holocene CWC from the Alboran Sea and the northern Gulf of Cadiz reveals relatively constant values (-8.6 to -9.0 and -9.5 to -10.4, respectively). Such values are similar to those of the surrounding present-day middepth waters from the Mediterranean Outflow Water (MOW; epsilon Nd approximate to -9.4) and Mediterranean Sea Water (MSW; epsilon Nd approximate to -9.9). In contrast, glacial epsilon Nd values for CWC collected at thermocline depth (550-827 m) in the southern Gulf of Cadiz display a higher average value (-8.90.4) compared to the present-day value (-11.70.3). This implies a higher relative contribution of water masses of Mediterranean (MSW) or South Atlantic origin (East Antarctic Intermediate Water, EAAIW). Our study has produced the first evidence of significant radiogenic epsilon Nd values (approximate to -8) at 19, 23-24, and 27 ka, which are coeval with increasing iceberg discharges and a weakening of Atlantic Meridional Overturning Circulation (AMOC). Since MOW epsilon Nd values remained stable during the last glacial period, it is suggested that these radiogenic epsilon Nd values most likely reflect an enhanced northward propagation of glacial EAAIW into the eastern Atlantic Basin.

Determining the spatial distribution and temporal development of evaporation at regional and global scales is required to improve our understanding of the coupled water and energy cycles and to better monitor any changes in observed trends and variability of linked hydrological processes. With recent international efforts guiding the development of long-term and globally distributed flux estimates, continued product assessments are required to inform upon the selection of suitable model structures and also to establish the appropriateness of these multi-model simulations for global application. In support of the objectives of the Global Energy and Water Cycle Exchanges (GEWEX) LandFlux project, four commonly used evaporation models are evaluated against data from tower-based eddy-covariance observations, distributed across a range of biomes and climate zones. The selected schemes include the Surface Energy Balance System (SEBS) approach, the Priestley–Taylor Jet Propulsion Laboratory (PT-JPL) model, the Penman–Monteith-based Mu model (PM-Mu) and the Global Land Evaporation Amsterdam Model (GLEAM). Here we seek to examine the fidelity of global evaporation simulations by examining the multi-model response to varying sources of forcing data. To do this, we perform parallel and collocated model simulations using tower-based data together with a global-scale grid-based forcing product. Through quantifying the multi-model response to high-quality tower data, a better understanding of the subsequent model response to the coarse-scale globally gridded data that underlies the LandFlux product can be obtained, while also providing a relative evaluation and assessment of model performance. Using surface flux observations from 45 globally distributed eddy-covariance stations as independent metrics of performance, the tower-based analysis indicated that PT-JPL provided the highest overall statistical performance (0.72; 61 W m−2; 0.65), followed closely by GLEAM (0.68; 64 W m−2; 0.62), with values in parentheses representing the R2, RMSD and Nash–Sutcliffe efficiency (NSE), respectively. PM-Mu (0.51; 78 W m−2; 0.45) tended to underestimate fluxes, while SEBS (0.72; 101 W m−2; 0.24) overestimated values relative to observations. A focused analysis across specific biome types and climate zones showed considerable variability in the performance of all models, with no single model consistently able to outperform any other. Results also indicated that the global gridded data tended to reduce the performance for all of the studied models when compared to the tower data, likely a response to scale mismatch and issues related to forcing quality. Rather than relying on any single model simulation, the spatial and temporal variability at both the tower- and grid-scale highlighted the potential benefits of developing an ensemble or blended evaporation product for global-scale LandFlux applications. Challenges related to the robust assessment of the LandFlux product are also discussed.

In this work we consider a numerical study of hydrodynamics in the coastal zone using two different models, SHYFEM (shallow water hydrodynamic finite element model) and MITgcm (Massachusetts Institute of Technology general circulation model), to assess their capability to capture the main processes. We focus on the north Adriatic Sea during a strong dense water event that occurred at the beginning of 2012. This serves as an interesting test case to examine both the models strengths and weaknesses, while giving an opportunity to understand how these events affect coastal processes, like upwelling and downwelling, and how they interact with estuarine dynamics. Using the models we examine the impact of setup, surface and lateral boundary treatment, resolution and mixing schemes, as well as assessing the importance of nonhydrostatic dynamics in coastal processes. Both models are able to capture the dense water event, though each displays biases in different regions. The models show large differences in the reproduction of surface patterns, identifying the choice of suitable bulk formulas as a central point for the correct simulation of the thermohaline structure of the coastal zone. Moreover, the different approaches in treating lateral freshwater sources affect the vertical coastal stratification. The results indicate the importance of having high horizontal resolution in the coastal zone, specifically in close proximity to river inputs, in order to reproduce the effect of the complex coastal morphology on the hydrodynamics. A lower resolution offshore is acceptable for the reproduction of the dense water event, even if specific vortical structures are missed. Finally, it is found that nonhydrostatic processes are of little importance for the reproduction of dense water formation in the shelf of the north Adriatic Sea.

Decadal climate predictions may have skill due to predictable components in boundary conditions (mainly greenhouse gas concentrations but also tropospheric and stratospheric aerosol distributions) and initial conditions (mainly the ocean state). We investigate the skill of temperature and precipitation hindcasts from a multi-model ensemble of four climate forecast systems based on coupled ocean-atmosphere models. Regional variations in skill with and without trend are compared with similarly analysed uninitialised experiments to separate the trend due to monotonically increasing forcings from fluctuations around the trend due to the ocean initial state and aerosol forcings. In temperature most of the skill in both multi-model ensembles comes from the externally forced trends. The rise of the global mean temperature is represented well in the initialised hindcasts, but variations around the trend show little skill beyond the first year due to the absence of volcanic aerosols in the hindcasts and the unpredictability of ENSO. The models have non-trivial skill in hindcasts of North Atlantic sea surface temperature beyond the trend. This skill is highest in the northern North Atlantic in initialised experiments and in the subtropical North Atlantic in uninitialised simulations. A similar result is found in the Pacific Ocean, although the signal is less clear. The uninitialised simulations have good skill beyond the trend in the western North Pacific. The initialised experiments show some skill in the decadal ENSO region in the eastern Pacific, in agreement with previous studies. However, the results in this study are not statistically significant (p ˜ 0.1) by themselves. The initialised models also show some skill in forecasting 4-year mean Sahel rainfall at lead times of 1 and 5 years, in agreement with the observed teleconnection from the Atlantic Ocean. Again, the skill is not statistically significant (p ˜ 0.2). Furthermore, uninitialised simulations that include volcanic aerosols have similar skill. It is therefore still an open question whether initialisation improves predictions of Sahel rainfall. We conclude that the main source of skill in forecasting temperature is the trend forced by rising greenhouse gas concentrations. The ocean initial state contributes to skill in some regions, but variations in boundary forcings such as aerosols are as important in decadal forecasting.

Summary The aim of the paper is to assess how climate change is reflected in the variation of the seasonal patterns of the monthly central England temperature time series between 1772 and 2013. In particular, we model changes in the amplitude and phase of the seasonal cycle. Starting from the seminal work of Thomson, various studies have documented a shift in the phase of the annual cycle, implying an earlier onset of the spring season at various European locations. A significant reduction in the amplitude of the seasonal cycle is also documented. The literature so far has concentrated on the measurement of this phenomenon by various methods, among which complex demodulation and wavelet decompositions are prominent. We offer new insight by considering a model that allows for seasonally varying deterministic and stochastic trends, as well as seasonally varying auto-correlation and residual variances. The model can be summarized as containing a permanent and a transitory component, where global warming is captured in the permanent component, on which the seasons load differentially. The phase of the seasonal cycle, in contrast, seems to be following the trend that was identified by Thomson with Earth's precession in a stable manner. We identify the reported fluctuations as transitory.

A large number of perturbed-physics simulations of version 3 of the Hadley Centre Atmosphere Model (HadAM3) were compared with the Clouds and the Earth's Radiant Energy System (CERES) estimates of outgoing longwave radiation (OLR) and reflected shortwave radiation (RSR) as well as OLR and RSR from the earlier Earth Radiation Budget Experiment (ERBE) estimates. The model configurations were produced from several independent optimization experiments in which four parameters were adjusted. Model–observation uncertainty was estimated by combining uncertainty arising from satellite measurements, observational radiation imbalance, total solar irradiance, radiative forcing, natural aerosol, internal climate variability, and sea surface temperature and that arising from parameters that were not varied. Using an emulator built from 14 001 “slab” model evaluations carried out using the climateprediction.net ensemble, the climate sensitivity for each configuration was estimated. Combining different prior probabilities for model configurations with the likelihood for each configuration and taking account of uncertainty in the emulated climate sensitivity gives, for the HadAM3 model, a 2.5%–97.5% range for climate sensitivity of 2.7–4.2 K if the CERES observations are correct. If the ERBE observations are correct, then they suggest a larger range, for HadAM3, of 2.8–5.6 K. Amplifying the CERES observational covariance estimate by a factor of 20 brings CERES and ERBE estimates into agreement. In this case the climate sensitivity range is 2.7–5.4 K. The results rule out, at the 2.5% level for HadAM3 and several different prior assumptions, climate sensitivities greater than 5.6 K.

It is generally assumed that changes in ocean circulation forced the abrupt climate changes during the Late Pleistocene, including the Younger Dryas event. Recently, however, it was proposed that variations in solar irradiance could have played a much more prominent role in forcing Pleistocene climate changes. Furthermore, two physical mechanisms were recently published that explain how relatively small changes in solar irradiance could have had a strong impact on the climate system. We discuss the possibility that an abrupt reduction in solar irradiance triggered the start of the Younger Dryas and we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual (14)C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an similar to 2500 year quasi-cycle-also found in the (14)C record-that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere. Moreover, the proposed two physical mechanisms could possibly explain how the North Atlantic thermohaline circulation was perturbed through an increase in precipitation together with iceberg influxes. In addition, the full magnitude of the Younger Dryas cooling as evidenced by terrestrial records in Europe could be explained. We conclude that a solar triggering of the Younger Dryas is a valid option that should be studied in detail with climate models. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.

It is generally assumed that changes in ocean circulation forced the abrupt climate changes during the Late Pleistocene, including the Younger Dryas event. Recently, however, it was proposed that variations in solar irradiance could have played a much more prominent role in forcing Pleistocene climate changes. Furthermore, two physical mechanisms were recently published that explain how relatively small changes in solar irradiance could have had a strong impact on the climate system. We discuss the possibility that an abrupt reduction in solar irradiance triggered the start of the Younger Dryas and we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual (14)C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an similar to 2500 year quasi-cycle-also found in the (14)C record-that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere. Moreover, the proposed two physical mechanisms could possibly explain how the North Atlantic thermohaline circulation was perturbed through an increase in precipitation together with iceberg influxes. In addition, the full magnitude of the Younger Dryas cooling as evidenced by terrestrial records in Europe could be explained. We conclude that a solar triggering of the Younger Dryas is a valid option that should be studied in detail with climate models. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.

We assess the skill of retrospective multiyear forecasts of North Atlantic ocean characteristics obtained with ocean-atmosphere-sea ice models that are initialized with estimates from the observed ocean state. We show that these multimodel forecasts can skilfully predict surface and subsurface ocean variability with lead times of 2 to 9 years. We focus on assessment of forecasts of major well-observed oceanic phenomena that are thought to be related to the Atlantic meridional overturning circulation (AMOC). Variability in the North Atlantic subpolar gyre, in particular that associated with the Atlantic Multidecadal Oscillation, is skilfully predicted 2-9 years ahead. The fresh water content and heat content in major convection areas such as the Labrador Sea are predictable as well, although individual events are not captured. The skill of these predictions is higher than that of uninitialized coupled model simulations and damped persistence. However, except for heat content in the subpolar gyre, differences between damped persistence and the initialized predictions are not significant. Since atmospheric variability is not predictable on multiyear time scales, initialization of the ocean and oceanic processes likely provide skill. Assessment of relationships of patterns of variability and ocean heat content and fresh water content shows differences among models indicating that model improvement can lead to further improvements of the predictions. The results imply there is scope for skilful predictions of the AMOC. © 2013. American Geophysical Union. All Rights Reserved.

[1] The potential use of continental fair-weather shallow cumuli as a way to retrieve the daily surface evaporative fraction over land is evaluated in convective conditions. The proposed method utilizes the fact that both the timing of cloud occurrence and the cloud-base height at the time of occurrence provide strong constraints on the surface energy balance and evaporative fraction. The retrieval is especially reliable in the presence of relatively stable and humid-free troposphere profiles. The advantage of the method is that it provides a more direct estimate of the surface evaporative fraction than indirect estimation based on inversion of a highly parameterized land-surface model. In addition, the evaporative fraction is obtained at a scale of a few kilometers, which is more pertinent for weather and climate studies. The retrieval strategy is tested and validated for three contrasting climates: the U.S. southern Great Plains, West Africa, and the Netherlands. We suggest that the use of satellite observations of shallow cumuli can help constrain the retrieval of the surface evaporative fraction within a data assimilation scheme/reanalysis.

[1] In decadal predictability studies, the subpolar Atlantic stands out as a region of high potential and real predictability. Since local temperature and salinity variations in the region are for a large part controlled by ocean dynamics, skillful predictability of the local ocean dynamics is a prerequisite to obtain multiyear predictability of other variables such as sea surface temperature. In this study, we discuss the predictability of the main ocean current system in the region, the subpolar gyre. From perfect model hindcasts exploiting initial condition information only from realistic ocean observation locations, we find that predictability is increased when Argo subsurface data are included. In our real-world experiments with initialized hindcasts, the observed decline in subpolar gyre strength of the mid-1990s is reproduced well and we find predictability of the subpolar gyre up to 2 years ahead, comparable to the skill of a damped persistence model.