The spatial and temporal characteristics of TOMS AI over the Tarim Basin, China

This paper has a dual focus. One is to study the spatial characteristics of dust activities over the Tarim Basin by locating dust active hot spots. The other is to study the temporal characteristics of dust activities over the Tarim Basin by applying the Extreme Value Analysis (EVA).Hot spots (in terms of dust loading) refer to relatively small (compared to the size of the whole source area), consistently active, dust producing areas. In this paper, Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) is used to identify hot spots in the Tarim Basin. This hot spot study suggests that dust emissions are inhomogeneous in the Tarim Basin area and the formation of the two hot spots is linked to both (1) a large amount of fine sandy sediments accumulated at the hot spot areas and (2) the basin's internal dust transport pathways which are controlled by the extreme bounding topography of the basin.Extreme Value Analysis (EVA) has been widely used in a variety of areas, but has not yet been applied in dust storm research. In this paper, 13 years Tarim Basin regional daily maximum TOMS AI data time series are constructed. By examining the statistics of the time series, a new method (outlier method) is developed to identify extreme values. EVA is applied and 100-year-return values are suggested. The interpretation of the 100-year-return values is discussed by referring to historical meteorological records and also climate change projections.