Tropical Cyclones have their origins from areas of low atmospheric pressure over warm waters in the tropics or subtropics.We have carefully studied the interconnection between the West African Weather Systems(WAWS)and...Tropical Cyclones have their origins from areas of low atmospheric pressure over warm waters in the tropics or subtropics.We have carefully studied the interconnection between the West African Weather Systems(WAWS)and their subsequent development into Tropical Cyclones.Between 2004 and 2005,we studied the interconnection and the teleconnexion between the WAWS and the various occurrences展开更多
This paper provides <span style="font-family:Verdana;">an </span><span style="font-family:Verdana;">analysis and a description of the best practices and lessons learned in the imp...This paper provides <span style="font-family:Verdana;">an </span><span style="font-family:Verdana;">analysis and a description of the best practices and lessons learned in the implementation of </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">Global Framework for Climate S</span><span style="font-family:Verdana;">ervices Adaptation Program in Africa (GFCS-APA) focusing on Tanzania </span><span style="font-family:Verdana;">coun</span></span><span style="font-family:Verdana;">try</span><span style="font-family:Verdana;">’s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> activities. GFCS-APA was the first multi-agency initiative imple</span><span style="font-family:Verdana;">mented </span><span style="font-family:Verdana;">under the Global Framework for Climate Services (GFCS) in two African</span><span style="font-family:Verdana;"> countries, namely Tanzania and Malawi with funding from the Royal</span><span style="font-family:Verdana;"> Govern</span><span style="font-family:Verdana;">ment of Norway. In Tanzania, the programme was implemented in two</span><span style="font-family:Verdana;"> phases from the year 2014 to 2021 in the three pilot districts of Kondoa, Longido and Kiteto located in Dodoma, Arusha and Manyara regions</span></span><span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> re</span><span style="font-family:Verdana;">spectively. The overarching goal of the programme was to enable bette</span><span style="font-family:Verdana;">r management of the risks caused by climate variability and change at all levels, from </span><span style="font-family:Verdana;">end-users to policy level, through development and incorporation of</span><span style="font-family:Verdana;"> science</span></span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">based climate in</span><span style="font-family:Verdana;">formation and prediction services into planning, policy and practice. The</span><span style="font-family:Verdana;"> programme focused on bridging the gap between provider</span></span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> and </span><span style="font-family:Verdana;">users of climate information and products through development of us</span><span style="font-family:Verdana;">er-driven climate services for food security, health and disaster risk reduction. </span></span><span style="font-family:Verdana;">This paper aimed to analyze lessons learned and best practices in the course of the implementation of the GFCS</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">APA phase I and II in Tanzania. A qualitative approach was employed to analyze the lessons learned and best practices, by extracting them and exploring further </span><span style="font-family:Verdana;">on </span><span style="font-family:Verdana;">their contribution </span><span style="font-family:Verdana;">to</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">enhancement of climate services, as well as their applicability and potentiality for scaling out in other </span><span style="font-family:Verdana;">regions </span></span><span style="font-family:Verdana;">with</span><span style="font-family:Verdana;">in Tanzania, and </span><span style="font-family:Verdana;">in</span><span style="font-family:Verdana;"> other countries. The results indicate the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">identified best practices and lessons learned contributed </span><span style="font-family:Verdana;">significantly in enhancing climate services, particularly in understanding, </span><span style="font-family:Verdana;">availability, accessibility, utilization, ownership and sustainability of climate services among users (farmers </span><span style="font-family:Verdana;">and pastoralists) of various gender, as well as intermediaries and deci</span><span style="font-family:Verdana;">sion</span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">ma</span><span style="font-family:;" "=""><span style="font-family:Verdana;">kers. Results also indicate the lessons learned and the documented best prac</span><span style="font-family:Verdana;">tices could influence </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">effectiveness of climate services in other areas, to</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> ad</span><span style="font-family:Verdana;">dress existing challenges in access, uptake and sustainability of climate ser</span><span style="font-family:Verdana;">vices. The best practices and lessons learned could be considered for integration in the future projects or operational activities in other regions within the coun</span><span style="font-family:Verdana;">try and other countries, particularly in the developing world, including </span><span style="font-family:Verdana;">Sub-</span></span><span style="font-family:Verdana;">Saharan Africa.</span>展开更多
Precise and accurate rainfall simulation is essential for Tanzania, where complex topography and diverse climatic influences result in variable precipitation patterns. In this study, the 31st October 2023 to 02nd Nove...Precise and accurate rainfall simulation is essential for Tanzania, where complex topography and diverse climatic influences result in variable precipitation patterns. In this study, the 31st October 2023 to 02nd November 2023 daily observation rainfall was used to assess the performance of 5 land surface models (LSMs) and 7 microphysics schemes (MPs) using the Weather Research and Forecasting (WRF) model. The 35 different simulations were then evaluated using the observation data from the ground stations (OBS) and the gridded satellite (CHIRPS) dataset. It was found that the WSM6 scheme performed better than other MPs even though the performance of the LSMs was dependent on the observation data used. The CLM4 performed better than others when the simulations were compared with OBS whereas the 5 Layer Slab produced the lowest mean absolute error (MAE) and root mean square error (RMSE) values while the Noah-MP and RUC schemes produced the lowest average values of RMSE and MAE respectively when the CHIRPS dataset was used. The difference in performance of land surface models when compared to different sets of observation data was attributed to the fact that each observation dataset had a different number of points over the same area, influencing their performances. Furthermore, it was revealed that the CLM4-WSM6 combination performed better than others in the simulation of this event when it was compared against OBS while the 5 Layer Slab-WSM6 combination performed well when the CHIRPS dataset was used for comparison. This research highlights the critical role of the selection of land surface models and microphysics schemes in forecasting extreme rainfall events and underscores the importance of integrating different observational data for model validation. These findings contribute to improving predictive capabilities for extreme rainfall events in similar climatic regions.展开更多
The Quasi-Biennial Oscillation(QBO)is a vital mode of stratospheric variability with significant influence on tropical and subtropical climate systems.However,its influence on precipitation variability across Eastern ...The Quasi-Biennial Oscillation(QBO)is a vital mode of stratospheric variability with significant influence on tropical and subtropical climate systems.However,its influence on precipitation variability across Eastern and Southern Africa remains insufficiently understood.This study examines the impact of the QBO on summer precipitation and associated circulation anomalies over Eastern and Southern Africa from 1979 to 2021.Using ERA5 and NOAA reanalysis datasets,we applied composite and correlation analyses to assess precipitation responses to westerly(WQBO)and easterly(EQBO)phases.Results show a dipole-like pattern,with WQBO linked to enhanced precipitation in both Eastern and Southern Africa,while EQBO is associated with reduced precipitation.Circulation analysis reveals that WQBO phases promote upper-level divergence,low-level moisture inflow,and vertical ascent,whereas EQBO phases enhance subsidence and upperlevel convergence.These findings highlight the QBO role in modulating precipitation through stratosphere-troposphere coupling and its interaction with regional circulation patterns.The quasi-periodic nature of QBO offers substantial potential for enhancing seasonal precipitation predictions when integrated with other regional circulations,such as the Botswana High and the Angola Low.展开更多
The Quasi-Biennial Oscillation(QBO)is a dominant mode of interannual variability in the tropical stratosphere,known to influence global weather and climate patterns through stratosphere-troposphere coupling.While its ...The Quasi-Biennial Oscillation(QBO)is a dominant mode of interannual variability in the tropical stratosphere,known to influence global weather and climate patterns through stratosphere-troposphere coupling.While its impacts on the Northern Hemisphere are well-documented,its role in the Southern Hemisphere subtropical climate remains less explored.This study investigates the relationship between the QBO and September surface air temperature(SAT)over Southern Africa during the early austral spring from 1979 to 2021.We find that the QBO’s easterly phase(EQBO)at 50 hPa is associated with a significant dipole pattern in SAT,characterized by warming over southeastern Africa and cooling along the southwestern coastal area.Analysis reveals that this temperature pattern is driven by a coherent teleconnection pathway:the EQBO forces a quasi-barotropic geopotential height anomaly,which modulates vertical velocity,leading to enhanced convection and increased cloud cover over the cooling region and suppressed convection over the warming area.Outgoing Longwave Radiation data confirm this dipole in convective activity.A latitudinal-vertical cross-section demonstrates the descent of QBOrelated wind anomalies into the subtropical troposphere,outlining the direct stratospheric pathway for this distant influence.Our results identify the QBO as a key stratospheric precursor for early spring temperature variability in Southern Africa,with important implications for improving regional seasonal forecasting.展开更多
文摘Tropical Cyclones have their origins from areas of low atmospheric pressure over warm waters in the tropics or subtropics.We have carefully studied the interconnection between the West African Weather Systems(WAWS)and their subsequent development into Tropical Cyclones.Between 2004 and 2005,we studied the interconnection and the teleconnexion between the WAWS and the various occurrences
文摘This paper provides <span style="font-family:Verdana;">an </span><span style="font-family:Verdana;">analysis and a description of the best practices and lessons learned in the implementation of </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">Global Framework for Climate S</span><span style="font-family:Verdana;">ervices Adaptation Program in Africa (GFCS-APA) focusing on Tanzania </span><span style="font-family:Verdana;">coun</span></span><span style="font-family:Verdana;">try</span><span style="font-family:Verdana;">’s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> activities. GFCS-APA was the first multi-agency initiative imple</span><span style="font-family:Verdana;">mented </span><span style="font-family:Verdana;">under the Global Framework for Climate Services (GFCS) in two African</span><span style="font-family:Verdana;"> countries, namely Tanzania and Malawi with funding from the Royal</span><span style="font-family:Verdana;"> Govern</span><span style="font-family:Verdana;">ment of Norway. In Tanzania, the programme was implemented in two</span><span style="font-family:Verdana;"> phases from the year 2014 to 2021 in the three pilot districts of Kondoa, Longido and Kiteto located in Dodoma, Arusha and Manyara regions</span></span><span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> re</span><span style="font-family:Verdana;">spectively. The overarching goal of the programme was to enable bette</span><span style="font-family:Verdana;">r management of the risks caused by climate variability and change at all levels, from </span><span style="font-family:Verdana;">end-users to policy level, through development and incorporation of</span><span style="font-family:Verdana;"> science</span></span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">based climate in</span><span style="font-family:Verdana;">formation and prediction services into planning, policy and practice. The</span><span style="font-family:Verdana;"> programme focused on bridging the gap between provider</span></span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> and </span><span style="font-family:Verdana;">users of climate information and products through development of us</span><span style="font-family:Verdana;">er-driven climate services for food security, health and disaster risk reduction. </span></span><span style="font-family:Verdana;">This paper aimed to analyze lessons learned and best practices in the course of the implementation of the GFCS</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">APA phase I and II in Tanzania. A qualitative approach was employed to analyze the lessons learned and best practices, by extracting them and exploring further </span><span style="font-family:Verdana;">on </span><span style="font-family:Verdana;">their contribution </span><span style="font-family:Verdana;">to</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">enhancement of climate services, as well as their applicability and potentiality for scaling out in other </span><span style="font-family:Verdana;">regions </span></span><span style="font-family:Verdana;">with</span><span style="font-family:Verdana;">in Tanzania, and </span><span style="font-family:Verdana;">in</span><span style="font-family:Verdana;"> other countries. The results indicate the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">identified best practices and lessons learned contributed </span><span style="font-family:Verdana;">significantly in enhancing climate services, particularly in understanding, </span><span style="font-family:Verdana;">availability, accessibility, utilization, ownership and sustainability of climate services among users (farmers </span><span style="font-family:Verdana;">and pastoralists) of various gender, as well as intermediaries and deci</span><span style="font-family:Verdana;">sion</span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">ma</span><span style="font-family:;" "=""><span style="font-family:Verdana;">kers. Results also indicate the lessons learned and the documented best prac</span><span style="font-family:Verdana;">tices could influence </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">effectiveness of climate services in other areas, to</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> ad</span><span style="font-family:Verdana;">dress existing challenges in access, uptake and sustainability of climate ser</span><span style="font-family:Verdana;">vices. The best practices and lessons learned could be considered for integration in the future projects or operational activities in other regions within the coun</span><span style="font-family:Verdana;">try and other countries, particularly in the developing world, including </span><span style="font-family:Verdana;">Sub-</span></span><span style="font-family:Verdana;">Saharan Africa.</span>
文摘Precise and accurate rainfall simulation is essential for Tanzania, where complex topography and diverse climatic influences result in variable precipitation patterns. In this study, the 31st October 2023 to 02nd November 2023 daily observation rainfall was used to assess the performance of 5 land surface models (LSMs) and 7 microphysics schemes (MPs) using the Weather Research and Forecasting (WRF) model. The 35 different simulations were then evaluated using the observation data from the ground stations (OBS) and the gridded satellite (CHIRPS) dataset. It was found that the WSM6 scheme performed better than other MPs even though the performance of the LSMs was dependent on the observation data used. The CLM4 performed better than others when the simulations were compared with OBS whereas the 5 Layer Slab produced the lowest mean absolute error (MAE) and root mean square error (RMSE) values while the Noah-MP and RUC schemes produced the lowest average values of RMSE and MAE respectively when the CHIRPS dataset was used. The difference in performance of land surface models when compared to different sets of observation data was attributed to the fact that each observation dataset had a different number of points over the same area, influencing their performances. Furthermore, it was revealed that the CLM4-WSM6 combination performed better than others in the simulation of this event when it was compared against OBS while the 5 Layer Slab-WSM6 combination performed well when the CHIRPS dataset was used for comparison. This research highlights the critical role of the selection of land surface models and microphysics schemes in forecasting extreme rainfall events and underscores the importance of integrating different observational data for model validation. These findings contribute to improving predictive capabilities for extreme rainfall events in similar climatic regions.
文摘The Quasi-Biennial Oscillation(QBO)is a vital mode of stratospheric variability with significant influence on tropical and subtropical climate systems.However,its influence on precipitation variability across Eastern and Southern Africa remains insufficiently understood.This study examines the impact of the QBO on summer precipitation and associated circulation anomalies over Eastern and Southern Africa from 1979 to 2021.Using ERA5 and NOAA reanalysis datasets,we applied composite and correlation analyses to assess precipitation responses to westerly(WQBO)and easterly(EQBO)phases.Results show a dipole-like pattern,with WQBO linked to enhanced precipitation in both Eastern and Southern Africa,while EQBO is associated with reduced precipitation.Circulation analysis reveals that WQBO phases promote upper-level divergence,low-level moisture inflow,and vertical ascent,whereas EQBO phases enhance subsidence and upperlevel convergence.These findings highlight the QBO role in modulating precipitation through stratosphere-troposphere coupling and its interaction with regional circulation patterns.The quasi-periodic nature of QBO offers substantial potential for enhancing seasonal precipitation predictions when integrated with other regional circulations,such as the Botswana High and the Angola Low.
基金ECMWF-ERA5 and NOAA for making their data available.
文摘The Quasi-Biennial Oscillation(QBO)is a dominant mode of interannual variability in the tropical stratosphere,known to influence global weather and climate patterns through stratosphere-troposphere coupling.While its impacts on the Northern Hemisphere are well-documented,its role in the Southern Hemisphere subtropical climate remains less explored.This study investigates the relationship between the QBO and September surface air temperature(SAT)over Southern Africa during the early austral spring from 1979 to 2021.We find that the QBO’s easterly phase(EQBO)at 50 hPa is associated with a significant dipole pattern in SAT,characterized by warming over southeastern Africa and cooling along the southwestern coastal area.Analysis reveals that this temperature pattern is driven by a coherent teleconnection pathway:the EQBO forces a quasi-barotropic geopotential height anomaly,which modulates vertical velocity,leading to enhanced convection and increased cloud cover over the cooling region and suppressed convection over the warming area.Outgoing Longwave Radiation data confirm this dipole in convective activity.A latitudinal-vertical cross-section demonstrates the descent of QBOrelated wind anomalies into the subtropical troposphere,outlining the direct stratospheric pathway for this distant influence.Our results identify the QBO as a key stratospheric precursor for early spring temperature variability in Southern Africa,with important implications for improving regional seasonal forecasting.
