TITLE:
Moist Potential Vorticity Vector for Diagnosis of Heavy Rainfall Events in Tanzania
AUTHORS:
Philbert Modest Luhunga, George Djolov, Edmund Mutayoba
KEYWORDS:
Moist Potential Vorticity Vector, Moist-Air Entropic Potential Temperature, Heavy Rainfall Events
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.4 No.9,
September
29,
2016
ABSTRACT: In this
paper, we modify the convective vorticity vector (CVV) defined as a cross product of
absolute vorticity and gradient of equivalent potential temperature to moist
potential vorticity vector (MPVV) defined as a cross product of
absolute vorticity () and the gradient of the moist-air
entropy potential temperature (). The patterns of (MPVV) are compared with the patterns of
heavy rainfall events that occurred over different regions in Tanzania on 20th to 22nd December, 2011 and on 5th to 8th May,
2015. Moreover, the article aimed at assessing the relative contributions of
the magnitude, horizontal and vertical components of (MPVV) detecting on the observed patterns of rainfall
events. Dynamic and thermodynamic variables: wind speed, temperature,
atmospheric pressure and relative humidity from numerical output generated by
the Weather Research and Forecasting (WRF) model running at Tanzania
Meteorological Agency (TMA) were used to compute MPVV. It
is found that MPVV provide accurate tracking of
locations received heavy rainfall, suggesting its potential use as a dynamic
tracer for heavy rainfall events in Tanzania.
Finally it is found that the first and second components of MPVV contribute almost equally in tracing locations
received heavy rainfall events. The magnitude of MPVV described
the locations received heavy rainfall events better than the components.