Characteristics of convections associated with the Tibetan Plateau vortices based on geostationary satellite data

Tibetan Plateau vortices (TPVs) are major rain producers over the Tibetan Plateau, some of which can move eastward off the plateau and trigger heavy rainfall over southwestern and eastern China. The infrared black body temperature (TBB) data, derived from geostationary meteorological satellite FY-2E in the period of May-August of 2010-2014, is utilized to investigate the characteristics of convections associated with the moving-off TPVs. During May-August, negative TBB anomalies appear over the tracks of the TPVs, but are located further north of the tracks in May and June than in July and August. Relative to the centre of TPVs, low TBB appears in the southeast and extends from southwest to northeast, whose values are smaller and ranges are larger before the TPVs move off than after moving off. Distributions of TBB at different evolution times show a close relationship with the characteristics of TPVs. The intensity, scales and shape of the convections linked to the TPVs are explored in the coordinates whose origin is the composite centre of the convections. Generally, convections associated with the TPVs are elliptic and stretch from southwest to northeast, with average spatial scales of approximately 3 degrees in the zonal and 2 degrees in the meridional direction. Convections in July and August are more intensive and lie southwest-northeast, and those in May and June are weaker with a quasi-zonal orientation. The horizontal scales of convections are much larger in May and July than those in June and August. Convections are usually larger and more intense before the TPVs move off than after moving off, corresponding to the changes of TPVs.