Trends in the start of the wet season over Africa

Kniveton, Dominic; Layberry, Russell; Williams, Charles; Peck, Mika

doi:10.1002/joc.1792

Cited by 31 publications

(19 citation statements)

References 29 publications

(35 reference statements)

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“…Figure 6 contains the onset and cessation for the 17 regions shown in Figure 4. These results are consistent with published onset and cessation dates in the literature for East Africa [Ngetich et al, 2014;Camberlin et al, 2009], the West Africa southern coastal region Adejuwon and Odekunle, 2006;Nguyen et al, 2011;Sultan and Janicot, 2003;Nicholson, 2013], and southern Africa [Shongwe et al, 2015;Kniveton et al, 2009].…”

Section: Movement Of the Itczsupporting

confidence: 92%

The onset and cessation of seasonal rainfall over Africa

2016

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Variation in the seasonal cycle of African rainfall is of key importance for agriculture. Here an objective method of determining the timing of onset and cessation is, for the first time, extended to the whole of Africa. The method is applied to five observational data sets and the ERA‐Interim reanalysis. Compatibility with known physical drivers of African rainfall, consistency with indigenous methods, and generally strong agreement between satellite‐based rainfall data sets confirm that the method is capturing the correct seasonal progression of African rainfall. The biannual rainfall regime is correctly identified over the coastal region of Ghana and the Ivory Coast. However, the ERA‐Interim reanalysis exhibits timing biases over areas with two rainy seasons, and both ERA‐Interim and the ARCv2 observational data set exhibit some inconsistent deviations over West Africa. The method can be used to analyze both seasonal‐interannual variability and long‐term change. Over East Africa, we find that failure of the rains and subsequent humanitarian disaster is associated with shorter as well as weaker rainy seasons, e.g., on average the long rains were 11 days shorter in 2011. Cessation of the short rains over this region is 7 days later in El Niño and 5 days earlier in La Niña years with only a small change in onset date. The methodology described in this paper is applicable to multiple data sets and to large regions, including those that experience multiple rainy seasons. As such, it provides a means for investigating variability and change in the seasonal cycle over the whole of Africa.

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Section: Movement Of the Itczsupporting

confidence: 92%

The onset and cessation of seasonal rainfall over Africa

2016

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“…Early planting can lead to increased yields but is very risky due to the high probability of false season starts. False season starts have been reported in several studies to be a high risk to crop production in SSA (Raes et al, 2004;Kniveton et al, 2009;Lone and Warsi, 2009;Mupangwa et al, 2011a). In our study the false season starts occurred, approximately, in one out of four seasons.…”

Section: Risk Management By Early Plantingsupporting

confidence: 61%

Risk management options in maize cropping systems in semi-arid areas of Southern Africa

Masvaya

Nyamangara

Descheemaeker

2018

Field Crops Research

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A B S T R A C TAlthough rainfed cropping in semi-arid areas is risky due to frequent droughts and dry spells, planting early with the first rains is often expected to result in yield benefits. We hypothesised that planting early leads to yield benefits if the planting coincides with a mineral N flush at the start of the season but leads to crop failure if there is a false start to the cropping season. The effects of different management options, including tillage (ploughing and ripping), mulch (two levels 0 and 2 t ha −1 ) and fertility amendments (five levels: 0; 20 and 40 kg N ha −1 ; 5 t manure ha −1 and 5 t ha −1 manure + 20 kg N ha −1 ) on grain yields were simulated using the calibrated and tested APSIM model over a 30-year period (1984-2015). Yields were simulated and compared across seven planting date scenarios (planting when cumulative rainfall of 20 mm was received in three consecutive days). Planting with the first rains with manure + 20 kg N ha −1 resulted in the best average yield of 2271 kg ha −1 whilst the poorest average yields of 22 kg ha −1 were observed with planting on 15 January with no fertility amendment (0 kg N ha −1 ). Planting early (1 Nov to 15 Nov) and with the first rains resulted in exceeding the food self-sufficiency threshold of 1080 kg ha -1 in 40-83 % of the cases if fertility amendments are applied, as well as a low probability of complete crop failure, ranging from 0 to 40%. Grain yield penalties due to a false start followed the trend: ripper + mulch > plough + mulch > ripper (no mulch) averaging 256, 190 and 182 kg ha -1 respectively across all the fertility treatments. The model was able to simulate the occurrence of the mineral N flush with the first rains. Its coincidence with planting resulted in average yield benefits of 712, 452, 382 and 210 kg ha -1 for the following respective planting dates: 1 Nov, 15 Nov, 30 Nov, variable date when > 20 mm rainfall was received. Early planting, in combination with reduced tillage, mulch and N containing fertility amendments is critical to reduce risk of crop failure in the smallholder cropping systems of semi-arid areas of southern Africa and achieve the best possible yields. January (Spear, 1968). It has been recommended that farmers plant https://doi.

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“…The farmers' reports and concerns reflect the strong influence of several features in the annual precipitation cycle on farmers' lives and the agricultural year in the Cuenca Auqui. The steadiness of these characteristics determines the success or failure of sowing, growing and harvesting (Ambrosino et al, 2014;Kniveton et al, 2009;Raes et al, 2004). To extract the agriculturally relevant information from the seasonal cycles of daily precipitation to be compared with the farmers' experiences, we defined eight criteria, mainly empirically and inspired by methods presented, for example, by Laux et al (2008).…”

Section: Available Recordsmentioning

confidence: 99%

Comparing peasants' perceptions of precipitation change with precipitation records in the tropical Callejón de Huaylas, Peru

et al. 2016

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Abstract. Pronounced hygric seasonality determines the regional climate and, thus, the characteristics of rainfed agriculture in the Peruvian Callejón de Huaylas (Cordillera Blanca). Peasants in the Cuenca Auqui on the eastern slopes above the city of Huaraz attribute recently experienced challenges in agricultural production mainly to perceived changes in precipitation patterns. Statistical analyses of daily precipitation records at nearby Recuay (1964Recuay ( to 2013 and Huaraz (1996 to 2013) stations do not corroborate the perceived changes. Either insufficient temporal resolution of available precipitation records or other environmental and sociopolitical factors impacting traditional farming methods may be the reason for the lack of concordance between the two information sources investigated in this study.

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Trends in the start of the wet season over Africa

Cited by 31 publications

References 29 publications

The onset and cessation of seasonal rainfall over Africa

The onset and cessation of seasonal rainfall over Africa

Risk management options in maize cropping systems in semi-arid areas of Southern Africa

Comparing peasants' perceptions of precipitation change with precipitation records in the tropical Callejón de Huaylas, Peru

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