Human-induced changes of surface albedo in Northern China from 1992-2012

Abstract

Land surface albedo is a key radiative forcing factor in Earth radiation budget, and its variation is highly related to land surface processes, such as land cover change. This study aimed to identify the contribution of human-induced albedo to regional land surface albedo change by analyzing the relationship between albedo and land cover change in northern China from 1992 to 2012. We first employed the time series decomposition method (TSDM) to decompose the satellite-based albedo to three components: seasonal cycle, trend, and residual information. We then analyzed the regional albedo characters over different land cover types and their corresponding variations induced by land cover conversion. The multi-year averaged albedo in northern China was 0.2285 ± 0.0646. The albedo over changed and unchanged area was 0.2435 ± 0.0840 and 0.2276 ± 0.0633, respectively. The contribution of human-induced albedo change to overall changes reached about 86%, which was mainly due to cultivation and urbanization. Trend analysis indicated that the albedo slightly increased in northern China, which may decrease regional solar radiation absorption. Fractional increases in croplands showed a positive correlation with albedo variation (R2 = 0.51). Human-induced albedo change would cause negative radiative forcing (-0.705 W/m2) and thus further promote cooling effects in northern China.