Agricultural irrigation impacts on land surface parameters detected from satellite data products in Northern China

In this study, the irrigation impact on land surface parameters was analyzed using a new irrigation map of China and remote sensing products during two time periods and three sub-regions. Based on this study, in North China, the mean Normalized Difference Vegetation Index (NDVI), visible band albedo, evapotranspiration (ET), daytime land surface temperature (LST) and nighttime LST during the growing season are 0.470, 0.081, 57.167 W/m², 301.815 K, and 283.683 K in the lightly irrigated area(where irrigation percentage in a pixel is bigger than or equals to 50%), 0.507, 0.078, 59.699 W/m², 301.606 K, and 283.745 K in the highly irrigated area (where irrigation percentage in a pixel is smaller than 50%), and 0.461, 0.081, 55.921 W/m², 301.137 K, and 283.379 K in rainfed areas, respectively. Overall, the highly irrigated areas show lower albedo, daytime LST, but higher NDVI, nighttime LST and ET than lightly irrigated/rainfed areas. Moreover, the differences between highly and lightly irrigated/rainfed areas are more obvious in Northwest China, the driest area of China, in summer rather than throughout the growing season. Our results indicate that satellite observation is a promising tool for studying the impact of irrigation in large scale.