Land-atmosphere coupling and diurnal temperature range over the contiguous United States

Soil moisture influences on daily maximum (T-max) and minimum (T-min) temperatures, and thus the diurnal temperature range (DTR) in summer, are statistically quantified across the contiguous Unites States using soil moisture from the Global Land Data Assimilation System and observational temperatures. A soil moisture feedback parameter is computed based on lagged covariance ratios. Over the zone from California through the Midwest to the Southeast, the soil moisture exhibits a negative feedback on DTR mainly through its damping effect on T-max. In contrast, a positive feedback on DTR dominates Arizona and New Mexico as the soil moisture exerts a stronger negative forcing on T-min relative to T-max. The feedback-induced variability accounts for typically 10-20% of the total DTR variance over regions where strong feedbacks are identified. The results provide a useful benchmark for evaluating climate model simulations, although the employed data and method have limitations that should be recognized. Citation: Zhang, J., W.-C. Wang, and L. Wu (2009), Land-atmosphere coupling and diurnal temperature range over the contiguous United States, Geophys. Res. Lett., 36, L06706, doi:10.1029/2009GL037505.