| 摘 要： |
Understanding historical changes in land surface albedo (ALB) is critical for projecting future climate changes over the Arctic. Previous studies have reported the important role of snow cover and vegetation growth in regulating Arctic land ALB, but their main influencing paths and separate contributions remain underexamined. In this study, the partial least squares path model (PLS-PM) and random forest model (RFM) are adopted to explore the dominant paths of three climate variables-temperature (Tem), precipitation (Pre) and wet days (WD)-in influencing the interannual variations in ALB (IVA) by regulating vegetation and snow cover. The results show that ALB in October and December exhibit significant (p < 0.05) upward and downward trends, respectively. ALB in the Northwest Territories, Victoria Island and Nunavut of the Arctic significantly (p < 0.05) increase in summer and October. The summer snow cover fraction (SCF) shows a significant positive correlation with ALB (R: 0.60.0.78), while significant negative (R = -0.60) and positive (R = 0.50) relations are found between the enhanced vegetation index (EVI) and ALB during July and September, respectively. According to PLS PM, the dominant paths that affect the IVA exhibit a prominent seasonal feature. Pre -> EVI -> ALB and Tem -> SCF -> ALB are identified as the main paths for ALB changes during spring, while in summer, the only significant path is Tem -> SCF -> ALB. In autumn, nonsignificant impacts on the variations in EVI and SCF (p > 0.05) are observed, while a significant path WD -> SCF -> ALB is found in winter. Based on RFM, the relative contribution (RC) of vegetation change to March IVA can reach 52.1 +/- 9.2%, while snow variations play a dominant role in April and May, with contributions of 57.8 +/- 8.4% and 68.4 +/- 4.1%, respectively. Seasonally, summer IVA is mainly impacted by snow (RC from 50.5 +/- 4.5% to 65.9 +/- 4.5%), while vegetation exerts the dominant influence on IVA in autumn except for September. In winter, however, the dominant strength of vegetation is weakened except in December, with IVA mainly controlled by snow (RC above 50%). |
在线留言
联系我们
所长信箱