Abstract
Abstract Irrigated agriculture accounts for 20% of global cropland area and may alter climate locally and globally, but feedbacks on clouds and rainfall remain highly uncertain, particularly in arid regions. Nonrenewable groundwater in arid regions accounts for 20% of global irrigation water demand, and quantifying these feedbacks is crucial for the prediction of long-term water use in a changing climate. Here, satellite data are used to show how irrigated crops in an arid environment alter land surface properties, cloud cover, and rainfall patterns. Land surface temperatures (LSTs) over the cropland are 5–7 K lower than their surroundings, despite a lower albedo, suggesting that Bowen ratio is strongly reduced (and latent heat fluxes increased) over the irrigated cropland. Daytime cloud cover is increased by up to 15% points (a relative increase of 60%), with increased cloud development in the morning and a greater afternoon peak in cloud. Cloud cover is significantly correlated with interannual variations in vegetation and LST. Afternoon rainfall also appears to be enhanced around the irrigation. The cloud feedback is the opposite of what has been previously observed in tropical and semiarid regions, suggesting different processes drive land–atmosphere feedbacks in very dry environments. Increased cloud and rainfall, and associated increases in diffuse radiation and reductions in temperature, are likely to benefit vegetation growth. Predictions of changes in crop productivity due to climate change and the impacts of global land-use change on climate and the use of water resources would therefore benefit from including these effects.
Highlights
Land-use and land-cover change (LULCC) alters the surface energy budget by modifying roughness, albedo, and the partitioning of incoming solar radiation into sensible and latent heat fluxes (Pielke et al 2011), Denotes content that is immediately available upon publication as open access
We have used satellite data to show a positive feedback between cropland and afternoon clouds in the arid Al-Jowf region in Saudi Arabia, linked to lower land surface temperatures that must be coupled to increased humidity over the cropland
The cropland is associated with 5–7-K reductions in Land surface temperatures (LSTs) relative to its surroundings, despite having a slightly lower albedo, and which must be accompanied by large increases in latent heat fluxes
Summary
Land-use and land-cover change (LULCC) alters the surface energy budget by modifying roughness, albedo, and the partitioning of incoming solar radiation into sensible and latent heat fluxes (Pielke et al 2011), Denotes content that is immediately available upon publication as open access. Any feedbacks between irrigated land and clouds or rainfall in arid regions will alter surface temperatures and radiation, affecting both crop productivity and crop water requirements, which will affect the long-term management of limited water resources.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
