###### Abstract  
Land use change can impact the land surface radiation budget and energy balance by changing surface biophysical processes. Based on satellite remote sensing data and land use data from 2000 to 2015, we quantitatively estimated radiative forcing induced by cropland expansion during the early 21 st century in northern China. The results showed that heat flux from the land surface to the atmosphere due to cropland expansion was quite variable in different climate zones. The heat flux increased in humid North China, whereas it decreased in arid Northwest China, semiarid Inner Mongolia, and humid Northeast China. Cropland expansion from woodland areas led to a general decline in the land surface heat flux to the atmosphere, which led to a cooling effect on the climate. The surface heat flux to the atmosphere due to cropland expansion in grassland areas displayed significant variations in different climate zones. The surface heat flux decreased only in humid Northeast China and arid Northwest China. The net surface radiation and latent heat flux both increased when grasslands were changed into cropland, but to different extents, which produced the differences in the surface heat flux to the atmosphere between different zones. radiative forcing; surface radiative energy balance; regional climate; cropland expansion; northern China +
Footnote †: journal: Applied Sciences  
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Footnote 1: email: {[PERSON], jia  
continental-scale land clearing, the cooling is triggered by increases in surface albedo and is reinforced by a land albedo-sea ice feedback mechanism [15]. This feedback is crucial in the model's predictions; without it, other biophysical processes may overwhelm the albedo effect to generate warming instead of cooling [15]. In-situ observations, land cover change, and land management change had similar impacts that averaged 2 K at the vegetation surface and were estimated at 1.7 K in the planetary boundary layer [16]. The differences in the type and the extent of the land use change determine the changes of albedo and emissivity, which then results in variations in the radiative forcing. To meet the demand of the world's population for food, the area of farmland has been increasing continuously. The effects of farmland expansion on regional and global climates through changing land surface parameters have been mainly described and quantitatively analyzed by observations, modeling data, or remote sensing methods. The conversion of forests and natural grasslands to croplands increases the albedo while causing decreases in the leaf area index (LAI) and surface roughness. Statistically significant annual warming over southeast Australia was detected by the use of a simple land surface model [17]. In Northeastern China, farmland expansion decreased the temperature by 0.06 \({}^{\circ}\)C, according to data from the SiB2 model [18]. Across Northeastern China over the last 300 years, surface albedo has been changed by cropland expansion, and this has resulted in climate warming effects during the non-rainy seasons through surface radiation processes, but climatic effects during the summer were not readily detected with the Weather Research and Forecasting (WRF) model [19]. In Eastern China, cropland expansion has produced warming and rainy effects during the last three centuries based on four 12-year simulations with the WRF-SSiB model [20]. The temperature in both summer and winter decreased when the conversion of forest to farmland occurred in Northeastern China, according to the WRF model data [21]. Because of data scarcity, limited spatial scales, and other disadvantages, field observations are unable to effectively describe the variations in key surface parameters and climatic changes on regional/local scales. Climate model simulations driven by land use change also have significant limitations because of the uncertainties in the models and the coarse resolution of the land use data [22].