西北地区东部沙尘暴转型对气候和生态环境变化的响应

Response of Sandstorm Transformation to Climate and Eco-environment Change in East Part of Northwest China

利用西北地区东部近50a较完整的沙尘暴资料序列和1981年以来NOAA/AVHRR的NDVI数据,通过量化反演关键区植被覆盖率,并结合土地详查等代用资料的校准,对西北地区东部沙尘暴转型的生态演变量化特征与基本型态及沙尘暴过程发生频次、持续时间和高发站沙尘暴启动风速的年代际演变特征进行了综合分析。结果表明:1951年以来,西北地区东部沙尘暴过程发生频次出现了由多到少的明显转型,年突变出现在1987年,春季突变出现于1986年;近50a,该区域年NDVI指数振荡幅度较大,并在波动中略有减小,生态环境整体呈退化趋势,在此背景下,沙尘暴过程持续时间明显增加,启动风速显著降低。依据生态/气候影响分析模型,在不同生态/气候型态下,西北地区东部沙尘暴过程频次和持续时间有明显差异,气候变化对沙尘暴过程发生频次具有明显的驱动作用,而生态环境的变化对沙尘暴过程持续时间有显著的调节与控制作用。

The sandstorm data in last 50 years and the quantitatively retrieved vegetation cover data from NOAA/AVHRR NDVI data since 1981 in the east part of Northwest China, which combined with calibrated detailed land-use data, were used to synthetically analyze the ecological change feature and basic model, sandstorm frequency, duration, and threshold wind speed in the area. The results show that, since 1951 the sandstorm in the east of Northwest China experienced a transformation from less to more, the annual change mutation occurred in 1987, the annual amplitude of NDVI in the area was large and showed a slow decreasing trend, the general eco-environment showed a degenerating trend. Under this circumstance, the duration of sandstorm increased, the threshold wind speed decreased. Study based on the eco-climate model shows that the sandstorm duration and frequency in the east of Northwest China are different, climate change drove the sandstorm frequency change, and eco-environment change had a significant adjust and control effect on the sandstorm duration.