A Method for Estimating Surface Albedo and Its Components for Partial Plastic Mulched Croplands
Shujing Qin, Sien Li, Kun Yang, Lu Zhang, Lei Cheng, Pan Liu, Dunxian She
Abstract
Abstract In partial plastic-mulch-covered croplands, the complicated coexistence of bare soil surface, mulched soil surface, and dynamically changing canopy surface results in challenges in accurately estimating field surface albedo ( α ) and its components (bare soil surface albedo α b , mulched soil surface albedo α m , and canopy surface albedo ( α c ) during the whole growth period. To accurately estimate α , α b , α m , and α c , and to quantify the three surfaces’ contributions to field shortwave radiation reflections ( F b , F m , F c ), 1) a modified two-stream (MTS) approximation solution that considered the effect of plastic mulch has been proposed to accurately estimate α and 2) dynamic variations of α b , α m , α c and F b , F m , F c have been characterized. Therein, α b and α m were determined from corresponding parameterization schemes, and α c was determined using mulched irrigated croplands surface albedo (MICA) relationship between α and α b , α m , and α c that was established in this study. Results indicated that 1) compared with measurements, considering the effect of plastic mulch will significantly improve estimation of α when the ground surface is not fully covered by the crop canopy, while not underestimating α by a mean value of 0.061 in the early growth period, and 2) mean values of α , α b , α m , and α c during the whole growth period were 0.198, 0.174, 0.308, and 0.160, respectively, while the corresponding F b , F m , and F c were 0.08, 0.42, and 0.50, respectively.