关键词: 土地利用/覆盖变化, 降水效应, 气候背景, 中国

Abstract:

Precipitation could be impacted significantly by Land Use/Cover Change (LUCC). However, the variability of impacts of LUCC on precipitation and its dependences on the large-scale climate background have been little studied. In this study, numerical experiments with the Weather Research and Forecasting (WRF) model for 21-year (1980-2000) were carried out. There were two experiments with exactly the same settings except for the underlying land use/cover. One experiment used land use/cover for the early 1980s (hereafter called EXP1980) and the other one used land use/cover for the 2000 (hereafter called EXP2000). Through comparing the two experiments with each other, the inter-annual variability of impacts of LUCC on summer precipitation over eastern China and its dependences on the large-scale climate background were disclosed. The results show that the LUCC exerted varied impacts on the summer precipitation along with the inter-annual variations of climate background. On the climate background of 1981, 1984, 1986, 1989, and 1996 (hereafter called LR years), the LUCC from the early 1980s to 2000 may lead to a decrease of precipitation over eastern China, in particularly in the southwest and northeast of China. On the climate background of 1992, 1993, 1994, 1995, 1997, and 1999 (hereafter called MR years), the LUCC may lead to an increase of precipitation over eastern China, particularly in Southwest and Northeast China. Between the LR years and MR years, climate backgrounds have significant differences. There was a higher geopotential height in the west and a lower geopotential height in the east in the MR years than those in the LR years. Thereby, there was an anomaly of high pressure over Mongolia and an anomaly of low pressure over the Sea of Okhotsk. As a consequence, there was more precipitation in the south and less precipitation in the north in MR years than those in LR years. Such differences of climate backgrounds between MR years and LR years simulated by WRF model were also presented by NCEP2 reanalysis dataset. All of findings suggest that, along with the decadal precipitation variations characterized by an increase in the south and a decrease in the north from the 1980s, in which LR years existed mostly, to the 1990s, in which MR years existed mostly, the increase in the south might be promoted by LUCC while the decrease in the north might be slowed down by LUCC.

Key words: land use/cover change, precipitation effects, climate background, China