Observational Evidence for Desert Amplification Using Multiple Satellite Datasets

Desert amplification identified in recent studies has large uncertainties due to data paucity over remote
deserts. Here we present observational evidence using multiple satellite-derived datasets that desert
amplification is a real large-scale pattern of warming mode in near surface and low-tropospheric
temperatures. Trend analyses of three long-term temperature products consistently confirm that
near-surface warming is generally strongest over the driest climate regions and this spatial pattern
of warming maximizes near the surface, gradually decays with height, and disappears in the upper
troposphere. Short-term anomaly analyses show a strong spatial and temporal coupling of changes in
temperatures, water vapor and downward longwave radiation (DLR), indicating that the large increase
in DLR drives primarily near surface warming and is tightly associated with increasing water vapor
over deserts. Atmospheric soundings of temperature and water vapor anomalies support the results of
the long-term temperature trend analysis and suggest that desert amplification is due to comparable
warming and moistening effects of the troposphere. Likely, desert amplification results from the
strongest water vapor feedbacks near the surface over the driest deserts, where the air is very sensitive
to changes in water vapor and thus efficient in enhancing the longwave greenhouse effect in a warming
climate.