Land Surface Temperature Response to Irrigated Paddy Field Expansion: a Case Study of Semi-arid Western Jilin Province, China

The irrigated paddy fields have expanded greatly at semi-arid western Jilin province of China in recent over ten years, the sources of which are rain-fed cornfields, swamp meadow and saline alkali land mainly. Based on regional land use data, remote sensing data and meteorological data, this paper evaluates the land surface temperature changes response to land surface biophysical processes changes resulting from land use change (LUC), and dissociates the effect of radiative change (albedo) and non-radiative change (evapotranspiration and turbulent process) quantitatively using the energy redistribution factor. The results show that, the total land surface temperature changes based on energy redistribution factor are consistent with that based on remote sensing data on the whole, which have significant and different seasonal variations for agriculture adjustment of rain-fed cornfields to irrigated paddy fields and nature land reclamation. Generally, the largest Land surface temperature changes (Delta Ts) are most pronounced in May and June for agriculture adjustment of rain-fed cornfields to irrigated paddy fields, which is -1.85 K averagely. Notable decline of albedo from saline alkali land to irrigated paddy fields in April to June greatly counteracts the cooling effect of non-radiative processes changes, while the largest Delta Ts is found of -2. 54 K in dry summer months of July and August. For swamp meadows to irrigated paddy fields, non-radiative process is strengthened from June to September, the cooling effect of which is -1.69 K averagely. This study provides a case reference of local temperature change and obvious changes of land surface non-radiative terms at semi-arid area for adjustment of agricultural activities and land use changes.