Spatial and Temporal Analysis of Rainfall and Temperature Extreme Indices in Tanzania

Abstract

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 0.69˚C, 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.

Analysis of Climate Change and Extreme Climatic Events in the Lake Victoria Region of Tanzania

“…In East African countries, climate change has already affected weather patterns and hydrological cycles. Several studies over East Africa region indicated that temperatures have increased, rainfall in particular, the long rains that are historically considered important for agriculture activities in the region have declined by later onset and earlier cessation (Wainwright et al, 2019;Borhara et al, 2020), the frequency and intensity of extreme weather events such as persistent drought and floods have increased (Kijazi and Reason, 2009a,b;Chang'a et al, 2017;Nicholson, 2017), the unpredictability of rainfall seasons has increased, and sea rise and coastal erosion have been noticed over many coastal regions (Tumbo et al, 2010;Liwenga et al, 2014;Mubaya et al, 2014). These events have affected water availability, food security, human health, and other socioeconomic livelihoods (Opiyo et al, 2014).…”

Assessment of Drought Event, its Trend and Teleconnected Factors Over Burundi, Central East Africa

“…These two decades are known to be the driest decades over the study domain. Dry conditions were also recorded in neighboring countries specifically Rwanda and Tanzania (Ngarukiyimana et al 2017b;Chang'a et al 2017;Idrissa F. Nkurunziza et al 2019). As shown in the figure, the fluctuations over a 1-month time scale between wet and dry conditions are difficult to depict.…”

“…Thereafter, the SQMK results showed that more rainfall fluctuations started from the 1990s decade, a period coinciding with the first abrupt point of forward and backward sequential statistic. The 1990s decade was also identified to be the starting period of an increasing in rainfall variability resulting in more extremes weather events across East Africa Ngarukiyimana et al 2017c;Chang'a et al 2017; It was found that more abrupt points occurred after the year 2005. However, according to previous SPI time series analyses, it was found that more dry events occurred within the period 1993-2005.…”

Comparative Analysis of the Performance of Satellite‐Based Rainfall Products Over Various Topographical Unities in Central East Africa: Case of Burundi

“…The evaluation has been conducted for 17 years ranging from 2000 to 2016. The choice of studying the period 2000–2016 is motivated by the fact that this period is found to record more extreme weather events not only over Burundi but also over East Africa in general (Ongoma et al, ; Chang'a et al, ; Ngarukiyimana et al, ; Nkunzimana et al, ). Therefore, an evaluation on daily scale for this period is of more concern.…”