Properties of strong off‐shore Borneo vortices: a composite analysis of flow pattern and composition as captured by ERA‐Interim

摘要

The Borneo vortex (BV) is an important source of extreme weather for Malaysia. We describe climatological properties of strong off‐shore BVs using a potential vorticity (PV) threshold analysis of ERA‐Interim data. The composite BV at the location of most likely high PV occurrence has a warm core with enhanced specific humidity between 800 and 200 hPa, and a dry layer above. Two effects contribute to this structure: Air is vertically transported upwards in the BV whilst precipitating and the large scale flow in which the BV is embedded advect dry, ozone‐rich air from the equatorial tropical tropopause layer towards higher latitudes. Copyright ? 2012 Royal Meteorological Society.