The assessment of uncertainties in satellite-derived global surface albedo products is a critical aspect for studying the climate, ecosystem change, hydrology or the Earth's radiant energy budget. However, it is challenged by the spatial scaling errors between satellite and field measurements. This study aims at evaluating the forthcoming MODerate Resolution Imaging Spectroradiometer (MODIS) (Collection V006) Bidirectional Reflectance Distribution Function (BRDF)/albedo productMCD43Dover aMediterranean agricultural area.Here,we present the results from the accuracy assessment of theMODIS blue-sky albedo. The analysis is based on collocated comparisonswith higher spatial resolution estimates from Formosat-2 that were first evaluated against local in situmeasurements. The intersensor comparison is achieved by taking into account the effective point spread function (PSF) for MODIS albedo, modeled as Gaussian functions in the North–South and East–West directions. The equivalent PSF is estimated by correlation analysis between MODIS albedo and Formosat-2 convolved albedo. Results show that it is 1.2 to 2.0 times larger in the East–West direction as compared to the North–South direction. We characterized the equivalent PSF by a full width at half maximum size of 1920 m in East–West, 1200 m in North–South. This provided a very good correlation between the products, showing absolute (relative) Root Mean Square Errors from 0.004 to 0.013 (2% to 7%), and almost no bias. By inspecting 1-km plots homogeneous in land cover type,we found poorer performances over rice and marshes (i.e., relative Root Mean Square Error of about 11% and 7%, and accuracy of 0.011 and −0.008, respectively), and higher accuracy over dry and irrigated pastures, as well as orchards (i.e., relative uncertainty b3.8% and accuracy b0.003). The study demonstrates that neglecting theMODIS PSFwhen comparing the Formosat-2 albedo against theMODIS one induces an additional uncertainty up to 0.02 (10%) in albedo. The consistency between fine and coarse spatial resolution albedo estimates indicates the ability of the daily MCD43D product to reproduce reasonably well the dynamics of albedoThe assessment of uncertainties in satellite-derived global surface albedo products is a critical aspect for studying the climate, ecosystem change, hydrology or the Earth's radiant energy budget. However, it is challenged by the spatial scaling errors between satellite and field measurements. This study aims at evaluating the forthcoming MODerate Resolution Imaging Spectroradiometer (MODIS) (Collection V006) Bidirectional Reflectance Distribution Function (BRDF)/albedo productMCD43Dover aMediterranean agricultural area.Here,we present the results from the accuracy assessment of theMODIS blue-sky albedo. The analysis is based on collocated comparisonswith higher spatial resolution estimates from Formosat-2 that were first evaluated against local in situmeasurements. The intersensor comparison is achieved by taking into account the effective point spread function (PSF) for MODIS albedo, modeled as Gaussian functions in the North–South and East–West directions. The equivalent PSF is estimated by correlation analysis between MODIS albedo and Formosat-2 convolved albedo. Results show that it is 1.2 to 2.0 times larger in the East–West direction as compared to the North–South direction. We characterized the equivalent PSF by a full width at half maximum size of 1920 m in East–West, 1200 m in North–South. This provided a very good correlation between the products, showing absolute (relative) Root Mean Square Errors from 0.004 to 0.013 (2% to 7%), and almost no bias. By inspecting 1-km plots homogeneous in land cover type,we found poorer performances over rice and marshes (i.e., relative Root Mean Square Error of about 11% and 7%, and accuracy of 0.011 and −0.008, respectively), and higher accuracy over dry and irrigated pastures, as well as orchards (i.e., relative uncertainty b3.8% and accuracy b0.003). The study demonstrates that neglecting theMODIS PSFwhen comparing the Formosat-2 albedo against theMODIS one induces an additional uncertainty up to 0.02 (10%) in albedo. The consistency between fine and coarse spatial resolution albedo estimates indicates the ability of the daily MCD43D product to reproduce reasonably well the dynamics of albed

An understanding of where and how strongly the surface energy budget is constrained by soil moisture is hindered by a lack of large‐scale observations, and this contributes to uncertainty in climate models. Here we present a new approach combining satellite observations of land surface temperature and rainfall. We derive a Relative Warming Rate (RWR) diagnostic, which is a measure of how rapidly the land warms relative to the overlying atmosphere during 10 day dry spells. In our dry spell composites, 73% of the land surface between 60°S and 60°N warms faster than the atmosphere, indicating water‐stressed conditions, and increases in sensible heat. Higher RWRs are found for shorter vegetation and bare soil than for tall, deep‐rooted vegetation, due to differences in aerodynamic and hydrological properties. We show how the variation of RWR with antecedent rainfall helps to identify different evaporative regimes in the major nonpolar climate zones.

The increasing shortage of water for crop irrigation in arid and semiarid regions is encouraging the use of non-conventional resources. In the last decade, seawater desalination has consolidated its position as an alternative source to increase the supply for agricultural irrigation in Spain and Israel, where the farmers’ acceptance is progressively rising, despite the supply price being much higher than that of other conventional water sources. This article describes the current situation of desalinated seawater production and supply to agriculture in the southeast of Spain, and analyzes key questions such as its role in regional water planning, the infrastructure needed for conveyance and distribution, the energy requirements, the production and distribution costs, and the final price to farmers. The study is based on descriptive and quantitative data collected from desalination plants and irrigation district managers through technical questionnaires and personal interviews. The results show how seawater desalination is effectively alleviating the regional constraints in the irrigated agriculture supply, and why it is becoming strategic to maintaining food production and socioeconomic development. However, the high-energy requirements and associated costs in comparison with other water sources limit a more widespread use for agriculture, and for this reason desalinated water still only plays a complementary role in most irrigation districts.