5 research outputs found
Assessment of the Impacts of Climate Change on Maize Production in the Southern and Western Highlands Sub-agro Ecological Zones of Tanzania
The Intergovernmental Panel on Climate Change (IPCC) fourth assessment report confirmed that climate change is unequivocal. It is coming to us faster with larger impacts and bigger risks than even most climate scientists expected as recently as a few years ago. One particular worry is the disastrous consequence to agriculture and food security sectors in many parts of the world, particularly in developing countries. Adaptation is the only option to reduce the impacts of climate change. However, before planning adaptation policies or strategies to climate change, it is important to assess the impacts of climate change at regional and local scale to have scientific evidence that would guide the formulation of such policies or strategies. In this study the impacts of climate change on rain-fed maize (Zea Mays) production in the southern and western highlands sub-agro ecological zones of Tanzania are evaluated. High resolution climate simulations from the Coordinated Regional Climate Downscaling Experiment_Regional Climate Models (CORDEX_RCMs) were used as input into the Decision Support System for Agro-technological Transfer (DSSAT) to simulate maize yield in the historical climate condition (1971–2000), present (2010–2039), mid (2040–2069), and end (2070–2099) centuries. Daily rainfall, solar radiations, minimum and maximum temperatures for the historical (1971–2000) climate condition and future climate projections (2010–2099) under two Representative Concentration Pathways (RCPs) RCP4.5 and RCP 8.5 were used to drive DSSAT. The impacts of climate change were assessed by comparing the average maize yields in historical climate condition against the average of simulated maize yields in the present, mid and end centuries under RCP4.5 and RCP8.5. Results of future maize yields estimates from DSSAT driven by individual RCMs under both RCP scenarios (RCP 4.5 and RCP 8.5) differs from one RCM to another and from one scenario to another. This highlight the uncertainty associated with the projection. Results from the ensemble average of the yields indicated that maize yields will decline in future climate condition by 3.1 and 5.3% under RCP 4.5 and RCP8.5, respectively. High decreases in maize yield of 9.6% are expected in the end centuries under RCP 8.5. The main reason for decline in maize yields during future climate is the increase in temperatures that will shorten the length of growing seasons. Seasonal minimum temperature and maximum temperature are expected to increase by 1.84 and 1.53°C, respectively under RCP 4.5 and by about 2.72 and 2.2°C, respectively, under RCP 8.5. Therefore it is recommended that more studies need to be carried, especially by crop breeders to find maize varieties that can withstand the impacts of increased temperatures over southern and western highlands sub-agro ecological zones of Tanzania
Homogeneity of Monthly Mean Air Temperature of the United Republic of Tanzania with HOMER
Copyright © 2014 Philbert M. Luhunga et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In accordance of the Creative Commons Attribution License all Copyrights © 2014 are reserved for SCIRP and the owner of the intellectual property Philbert M. Luhunga et al. All Copyright © 2014 are guarded by law and by SCIRP as a guardian. The long-term climate datasets are widely used in a variety of climate analyses. These datasets, however, have been adversely impacted by inhomogeneities caused by, for example relocations of meteorological station, change of land use cover surrounding the weather stations, substitution of meteorological station, changes of shelters, changes of instrumentation due to its failure or damage, and change of observation hours. If these inhomogeneities are not detected and adjusted properly, the results of climate analyses using these data can be erroneous. In this paper for the first time, monthly mean air temperatures of the United Republic of Tanzania are homogenized by using HOMER software package. This software is one of the most recent homogenization software and exhibited the best results in the comparative analysis performed within the COST Action ES0601 (HOME)
Analysis of tropospheric radio refractivity over Julius Nyerere International Airport, Dar es Salaam
meteorological parameters-is of fundamental importance in planning and advancing
the understanding of radio wave propagation and wireless communication systems
within the troposphere. The vertical profiles of radio refractivity gradient (G) within
1km above the earth’s surface are important for the estimation of anomalous
propagation (AP) of microwave radiation. Furthermore the effect of AP in weather
radar measurements may be important as spurious echoes from distant ground
targets may appear as precipitation leading to incorrect rainfall estimations. AP may
also affect dramatically the quality of clear air radar observations. In this paper,we
present the vertical and temporal variations of refractive index represented by
refractivity (N-units) and refractivity gradient (G) (N-units km-1) in the troposphere
to evaluate the occurrence of AP over Julius Nyerere International Airport (JNIA),
Dar es Salaam, Tanzania. Meteorological data of air temperature, relative humidity,
and atmospheric pressure collected from radiosonde station at JNIA during January,
February, August, 2012 and September, October, and November, 2013, were used to
compute refractivity, refractive index and refractivity gradient. The percentage of
occurrences of super-refraction, sub-refraction, normal-refraction and ducting
conditions are presented. Results reveal that, the tropospheric radio wave
propagation conditions over JNIA have varying degree of occurrence with normalrefraction
conditions prevalent at all the levels except in February, 2012. During
this month, super-refraction and normal-refraction conditions have prevailed at the
altitude of 1km. The presented results in this paper indicate how the variation in
meteorological parameters such as humidity and temperature in the lower
troposphere can cause AP. These results can be used by air traffic controllers at:
Tanzania Civil Aviation Authority (TCAA) surveillance radar, which is located at JNIA and TMA weather radar, which is located 10km from JNIA, to improve performance of their radars to detect and eliminate false echoes from AP of the radar beam
Spatial and Temporal Analysis of Rainfall and Temperature Extreme Indices in Tanzania
Climate extreme indices in Tanzania for the period 1961-2015 are analyzed
using quality controlled daily rainfall, maximum and minimum temperatures
data. RClimdex and National Climate Monitoring Products (NCMP) software
developed by the commission for Climatology of the World Meteorological
Organization (WMO) were used for the computation of the indices at the respective
stations at monthly and annual time scales. The trends of the extreme
indices averaged over the country were computed and tested for statistical
significance. Results showed a widespread statistical significant increase in
temperature extremes consistent with global warming patterns. On average,
the annual timescale indicate that mean temperature anomaly has increased
by 0.69ËšC, mean percentage of warm days has increased by 9.37%, and mean
percentage of warm nights has increased by 12.05%. Mean percentage of
cold days and nights have decreased by 7.64% and 10.00% respectively. A
non-statistical significance decreasing trends in rainfall is depicted in large
parts of the country. Increasing trend in percentage of warm days and warm
nights is mostly depicted over the eastern parts of the country including areas
around Kilimanjaro, Dar-es-Salaam, Zanzibar, Mtwara, and Mbeya regions.
Some parts of the Lake Victoria Basin are also characterized by increasing
trend of warm days and warm nights. However, non-statistical significant decreasing
trends in the percentage of warm days and warm nights are depicted
in the western parts of the country including Tabora and Kigoma regions and
western side of the lake Victoria. These results indicate a clear dipole pattern
in temperature dynamics between the eastern side of the country mainly influenced
by the Indian Ocean and the western side of the country largely influenced
by the moist Congo air mass associated with westerly winds. The results
also indicate that days and nights are both getting warmer, though, the
warming trend is much faster in the minimum temperature than maximum
temperature.The paper is publishedThe authors wish to thank The Tanzania Meteorological Agency for providing
data used in this study and WMO for providing guidance in the analysis of climate
extreme in climate time series
Links between observed micro-meteorological variability and land-use patterns in the highveld priority area of South Africa
Links between spatial and temporal variability of Planetary Boundary Layer meteorological quantities and existing land-use patterns are still poorly understood due to the non-linearity of air–land interaction processes. This study describes the results of a statistical analysis of meteorological observations collected by a network of ten Automatic Weather Stations. The stations were in operation in the highveld priority area of the Republic of South Africa during 2008–2010. The analysis revealed localization, enhancement and homogenization in the inter-station variability of observed meteorological quantities (temperature, relative humidity and wind speed) over diurnal and seasonal cycles. Enhancement of the meteorological spatial variability was found on a broad range of scales from 20 to 50 km during morning hours and in the dry winter season. These spatial scales are comparable to scales of observed land-use heterogeneity, which suggests links between atmospheric variability and land-use patterns through excitation of horizontal meso-scale circulations. Convective motions homogenized and synchronized meteorological variability during afternoon hours in the winter seasons, and during large parts of the day during the moist summer season. The analysis also revealed that turbulent convection overwhelms horizontal meso-scale circulations in the study area during extensive parts of the annual cycleThe authors would like to acknowledge the bilateral Norway–South Africa project
180343/S50 “Analysis and the Possibility for Control of Atmospheric Boundary Layer
Processes to Facilitate Adaptation to Environmental Changes” co-funded by the South
African National Research Foundation (NRF) and the Norwegian Research Council
(NRC). A significant part of this work has been developed under the NRC project
191516/V30 “Planetary boundary layer feedback in the Earth's Climate System”, under
the European Research Council Advanced Grant, FP7-IDEAS, 227915 “Atmospheric
planetary boundary layers: physics, modeling and its role in the Earth system”, and under
a grant from the Government of the Russian Federation (project code 11.G34.31.0048).http://link.springer.com/journal/703hb201