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Vol.4 , No. 5, Publication Date: Dec. 5, 2017, Page: 78-85
 in the diagnosis of rainfall events over different regions in Tanzania. The main purpose of the article is to compute and compare qualitatively the patterns of MPV derived from the gradient of the moist air entropy potential temperature (<i>θ<sub>s</sub></i>) and heavy rainfall events that occurred over different regions in Tanzania on 20<sup>th</sup> December, 2011. Moreover, the article aims at assessing the relative contributions of horizontal and vertical components of MPV on detecting the location received heavy rainfall events. Wind speed, temperature, atmospheric pressure and relative humidity from the numerical output generated by the Weather Research and Forecasting (WRF) model were used to compute <i>θ<sub>s</sub></i> and MPV. Results indicated that MPV at 700 hPa exhibit positive values, over/near the areas received heavy rainfall due to local instability associated with possible continent/ocean contrast and continent/Lakes contrast. When compared with the observed rainfall, MPV provides fairly accurate tracking of location received rainfall, suggesting its potential use as a dynamic tracer of heavy rainfall events in Tanzania. Finally, it is found that in contrast to the mid-latitude and extra tropical regions where the vertical component of the MPV is larger than horizontal parts, in Tanzania which is located close to the Equator the horizontal parts are larger than the vertical part in the upper troposphere and the vertical part is larger than the horizontal parts in the lower troposphere.&picture=http://www.aascit.org/aascit/decorators/img/journal/904.jpg)
| [1] | Philbert Modest Luhunga, Research Section, Division of Research and Applied Meteorology, Tanzania Meteorological Agency, Dar es Salaam, Tanzania. |
| [2] | Chuki Athumani Sangalugembe, Numerical Weather Prediction (NWP) Section, Division of Forecasting Services, Tanzania Meteorological Agency, Dar es Salaam, Tanzania. |
This article, presents a first attempt to use Moist Potential Vorticity (MPV) in the diagnosis of rainfall events over different regions in Tanzania. The main purpose of the article is to compute and compare qualitatively the patterns of MPV derived from the gradient of the moist air entropy potential temperature (θs) and heavy rainfall events that occurred over different regions in Tanzania on 20th December, 2011. Moreover, the article aims at assessing the relative contributions of horizontal and vertical components of MPV on detecting the location received heavy rainfall events. Wind speed, temperature, atmospheric pressure and relative humidity from the numerical output generated by the Weather Research and Forecasting (WRF) model were used to compute θs and MPV. Results indicated that MPV at 700 hPa exhibit positive values, over/near the areas received heavy rainfall due to local instability associated with possible continent/ocean contrast and continent/Lakes contrast. When compared with the observed rainfall, MPV provides fairly accurate tracking of location received rainfall, suggesting its potential use as a dynamic tracer of heavy rainfall events in Tanzania. Finally, it is found that in contrast to the mid-latitude and extra tropical regions where the vertical component of the MPV is larger than horizontal parts, in Tanzania which is located close to the Equator the horizontal parts are larger than the vertical part in the upper troposphere and the vertical part is larger than the horizontal parts in the lower troposphere.
Keywords
Moist Potential Vorticity, Moist Air Entropic Potential Temperature, Rainfall Events
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