Diurnal surface temperature difference index derived from ground-based meteorological measurements for assessment of moisture availability

► The present study is the first to attempt to apply the diurnal surface temperature range to quantification of the moisture availability (ma) of vegetated land. ► A new index (NTDI) has been proposed to quantify (ma) and validated with observations from grassland of the Loess Plateau-China. NTDI has a strikingly high correlation with ma (R2 = 0.97, p < 0.001). ► The advantage of NTDI is that it can be used to non-destructive describe surface wetness conditions, such as ma. ► Relay of NTDI on basis of biophysical conditions makes it a potent tool for assessing and monitoring agricultural drought over a large scale on different environments.