Precipitation under Subtropical High Conditions: Evidence and Implications
The Evidence of Considerable Precipitation Occurring under Subtropical High Condition and Its Implications

The impact of the subtropical high (STH) on precipitation was investigated on a daily timescale using matched NCEP and the Global Precipitation Climatology Project (GPCP) datasets. Comparison of the conditional probability (intensity) of precipitation under STH conditions with that under non-STH conditions suggests that the presence of the STH conditions has a limited impact on local precipitation. In the West Pacific Subtropical High (WPSH) and the North Atlantic Subtropical High (NASH), precipitation was only 30% lower under STH conditions than under non-STH conditions. The STH conditions had somewhat more impact on precipitation intensity, but it was still 50% less than the intensity under non-STH conditions (mean of roughly 5 mm d 1). Precipitation under STH conditions was found to be highly correlated with vertical motion. Active updrafts occurring even under STH conditions are essential for frequent occurrences and moderate intensities of precipitation.