Landuse and land cover changes and dust storms in Tarim Basin Northwest China

摘要

MODIS image products were used to examine dust and sand storms occurred in Tarim Basin and identify major land cover types that may have contributed most to the recent severe dust storms. The near daily global coverage and multispectral capability of the MODIS sensors have made MODIS image products one of the best satellite observation data sources for monitoring large-scale Earth surface features and phenomena. The Level 1-B granule image quicklooks provided by the MODIS Atmosphere Science Team have proved sufficient for tracking dust storms in Tarim Basin. Within the last twenty-two months, Tarim Basin was covered by different scales of dust or sand storms almost year round. However, the basin-wide dust or sand storms were rare and they occurred mostly in March and April, when soil surface protection is the poorest and wind speed is the highest. As indicated by the compiled image quicklooks series, all dusts and sands were derived from within the basin. Once suspended in the air they were confined to the basin by the high mountains bordering the Basin. Only a relative small amount of dusts were exported to the east when they were associated with strong cold frontal systems. Analysis on the land cover type maps derived from full-resolution and cloud free MODIS Level 1-B radiance images suggest that the former Tarim River delta complex and current and past fluvial plains are the newest additions to the source areas of dust and sands. These two land cover types deserve the highest priority in the restoration of desert ecosystems effects in the region.