Reposted from the NoTricksZone
By P Gosselin on March 5, 2021
A new study confirms that climate variability in Africa is related to natural oceanic and solar cycles. No mention of CO2.
Image source: “Decadal and multi-decadal natural variability of African precipitation”.
A new study analyzes patterns of natural precipitation variability and can provide crucial support for African countries in predicting seasonal precipitation for agriculture and in protecting against drought and heavy rainfall.
Understanding natural cycles is key to modeling projections
Adequate rainfall is a basic requirement for productive agriculture and food security for the population. Until recently, however, it was not possible to reliably predict precipitation several months in advance, which repeatedly led to unexpected crop failures. However, there has been progress over the past few years. Exciting correlations between temperature and air pressure patterns in the world’s oceans with precipitation and droughts in Africa and on other continents have repeatedly been reported in the literature.
A group of researchers led by Horst-Joachim Lüdecke wanted to know more and used statistical methods to meticulously search for patterns in the monthly precipitation data of 49 African countries for the period 1901 to 2017.
“Large number of robust correlations”
The scientists compared the fluctuations in precipitation with five oceanic indices of natural origin firmly anchored in science and with solar activity. The evaluation revealed a large number of robust correlations on the African continent with characteristic seasonal patterns. It has been known for some time that the Atlantic influences precipitation in Morocco and the Sahel zone via the so-called Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO). Influences from the Indian and Pacific Oceans have so far been reported in East Africa.
Lüdecke and his team were able to confirm these relationships and add many other relationships that differ monthly with a high temporal resolution.
Since some of the correlations have a time lag of up to 11 months, valuable forecasting possibilities now open up. These are of great practical use for agricultural planning as well as for protection against droughts and heavy rainfall. Horst-Joachim Lüdecke explains: “At the beginning of the year, for example, there was heavy rainfall in parts of Namibia, which caused devastating floods. Our assessment showed that precipitation intensity in southwest Africa increases regularly in the presence of a negative NAO ocean cycle. Therefore, suitable precautionary measures can be taken in the region in the future if such a constellation emerges again. “
Lake Victoria is associated with the cycles of the Indian Ocean
Co-author Sebastian Lüning from the Institute for Hydrography, Geoecology and Climate Sciences describes another example: “The water level of Lake Victoria in East Africa fell to a historic low in 2006, which was cause for concern at the time. As a result, however, the lake level rose again and reached an all-time high at the end of 2020. Today we know: The driver of the changes is apparently the so-called dipole in the Indian Ocean. Lake Victoria normally rises when the index is positive and then falls when the index is negative [See article here]. We were able to demonstrate such a connection in our study for the rainy season in October and November. “
A co-author from the Technical University of Berlin played a key role in the complex statistics of the study.
Important forecasting tool for agriculture
The team of authors hopes: “Our results offer local and humanitarian planners a good tool to better assess the risk of drought, which changes from year to year. This enables the timely creation of additional irrigation options in agriculture or the purchase of food in particularly dry years. “
The study was published in early March in the renowned journal “Journal of Hydrology – Regional Studies” and can be downloaded free of charge. This was particularly important for the authors, as the results are thus freely available to all colleagues at African universities and research institutions. The publication fee was kindly taken over by the sponsor Jens Kröger.
The original publication can be downloaded here free of charge (Open Access). Another link to the appendix with numerous additional analyzes and data can be found in the online article in Appendix A.