A comparison study of summer-time synoptic-scale waves in South China and the Yangtze River basin using the TRMM Multi-Satellite Precipitation Analysis daily product

Summer-time synoptic-scale waves in South China and the Yangtze River basin are quantified and compared by means of analyzing the 6-year (1998–2004) TRMM Multi-Satellite Precipitation Analysis (TMPA) daily product. An innovative 3-dimensional spectrum analysis method is applied. The results indicate that synoptic-scale waves appearing in South China prominently propagate westward within a zonal wavenumber range of 9–21 and a frequency range of −0.12–−0.22 cycles day⁻¹, while those in the Yangtze River basin primarily move eastward with the same characteristic wavenumbers of 9–21, but within a frequency range of 0.2–0.29 cycles day⁻¹. Zonal and meridional distributions, and seasonal variations of these waves are further explored and compared. It shows that summer-time synoptic-scale waves in the South China result from the northward migration and oscillation of the Intertropical Convergence Zone (ITCZ) in the western Pacific, whereas the ones in the Yangtze River basin are generally related to the synoptic troughs within the westerly flow, originating from the Qinghai-Tibet Plateau. Supported by the special grant from the National Natural Science Foundation of China (Grant No.40428002) and the National Key Basic Research and Development Program of China (Grant No. 2004CB418303)