Diagnosing the Droughts and Floods in Equatorial East Africa during Boreal Autumn 2005–08

Hastenrath, Stefan; Polzin, Dierk; Mutai, Charles

doi:10.1175/2009jcli3094.1

Cited by 56 publications

(43 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The crisis situation evoked by the droughts was exacerbated by abrupt shifts to flood conditions. The floods occurred in 2006, 2009, and 2010 (Hastenrath et al , ) and again in both 2011 and 2013 (Figure (b)).…”

Section: Resultsmentioning

confidence: 88%

“…This implies that the causal mechanism of the recent droughts is likely to be one that affects both seasons. Two inter‐related factors have been implicated in other studies, the Indian Ocean Dipole/Zonal Mode (an opposition between temperatures in the eastern and western Indian Ocean) (Webster et al , ) and equatorial westerlies over the Indian Ocean (Hastenrath et al , ). Both influence eastern Africa by enhancing subsidence over the region.…”

Section: Resultsmentioning

confidence: 96%

See 1 more Smart Citation

An analysis of recent rainfall conditions in eastern Africa

Nicholson

2015

Int. J. Climatol.

View full text Add to dashboard Cite

This article examines recent rainfall conditions in two sectors of eastern Africa, the summer rainfall region and the equatorial rainfall region with rainy seasons in the boreal spring and boreal autumn. The analysis covers the years 1998–2014 and is carried out using TRMM 3B43 Version 7 rainfall estimates. In both regions, extensive periods of anomalously low rainfall and prolonged drought have prevailed since roughly 2008. Prior to that time, only three periods of drought are noteworthy 1998/1999, 2000, and 2005. The post‐2008 drought conditions were interrupted by floods in both regions in February 2010 and in several years in the equatorial region. This rapid alternation between extremes creates additional hardships on the population. Two notable results emerge from this analysis. One is the tendency for similar trends in interannual variability in both regions, despite vastly different rainfall regimes. The other is the persistence of recent droughts through several rainy seasons. The implication of these results is that one or more factors in interannual variability is operative in all seasons. This could account for the common trends in the equatorial and summer rainfall regions.

show abstract

Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 96%

An analysis of recent rainfall conditions in eastern Africa

Nicholson

2015

Int. J. Climatol.

View full text Add to dashboard Cite

show abstract

“…At least partial recovery occurred early in the 21 st century. In other parts of Africa, some very extreme years occurred between 1950 and the present time (Kijazi and Reason, 2009;Hastenrath et al, 2010). The mid-1970s included some of the wettest years on record for parts of southern and eastern Africa, drought appears to have become more frequent and more intense (Funk et al, 2013;Hoell and Funk, 2014;Nicholson, 2014a).…”

Section: The Period Of Recent Warming (1950 -2015 Ce)mentioning

confidence: 99%

“…In the Sahel and in eastern Africa, drought years have been interspersed with extreme floods. Droughts occurred in eastern Africa in 2005, followed by floods in 2006 (Hastenrath et al, 2007;Kijazi and Reason, 2009;Hastenrath et al, 2010). An extreme shift between drought and flood also occurred in November of 2010 and 2011, leading to the above-mentioned lake transgressions.…”

Section: The Period Of Recent Warming (1950 -2015 Ce)mentioning

confidence: 99%

African hydroclimatic variability during the last 2000 years

Nash

Cort

Chase

et al. 2016

Quaternary Science Reviews

View full text Add to dashboard Cite

The African continent is characterised by a wide range of hydroclimate regimes, ranging from humid equatorial West Africa to the arid deserts in the northern and southern subtropics. The livelihoods of much of its population are also vulnerable to future climate change, mainly through variability in rainfall affecting water resource availability. A growing number of data sources indicate that such hydroclimatic variability is an intrinsic component of Africa's natural environment. This paper, co-authored by members of the PAGES Africa 2k Working Group, presents an extensive assessment and discussion of proxy, historical and instrumental evidence for hydroclimatic variability across the African continent, spanning the last two millennia. While the African palaeoenvironmental record is characterised by spatially disjunctive datasets, with often less-than-optimal temporal resolution and chronological control, the available evidence allows the assessment of prominent spatial patterns of palaeomoisture variability through time. In this study, we focus sequentially on data for six major time windows: the first millennium AD, the Medieval Climate Anomaly (900-1250 CE), the Little Ice Age (1250-1750 CE), the end of the LIA (1750-1850 CE), the Early Modern Period , and the period of recent warming (1950 onwards). This results in a continentwide synthesis of regional moisture-balance trends through history, allowing consideration of possible driving mechanisms, and suggestions for future research.

show abstract

“…Strong negative annual mass balance rates in the 1990s resulted from the loss of the firn body and accompanying decrease of albedo [12]. The moderate mass loss between 2004 and 2010 is potentially due to very dry conditions, which favor the more energetically demanding ablation process of sublimation over melt [17,38], while the increase of negative mass balance rates since 2010 is caused by decreasing albedo, due to sediment accumulation and increased longwave heating from the surroundings and the recently developed rock outcrops (Figure 7). [12].…”

Section: Changes Of Glacier Volumementioning

confidence: 99%

Mapping the Loss of Mt. Kenya’s Glaciers: An Example of the Challenges of Satellite Monitoring of Very Small Glaciers

et al. 2018

View full text Add to dashboard Cite

Abstract:Since the last complete glacier mapping of Mt. Kenya in 2004, strong glacier retreat and glacier disintegration have been reported. Here, we compile and present a new glacier inventory of Mt. Kenya to document recent glacier change. Glacier area and mass changes were derived from an orthophoto and digital elevation model extracted from Pléiades tri-stereo satellite images. We additionally explore the feasibility of using freely available imagery (Sentinel-2) and an alternative elevation model (TanDEM-X-DEM) for monitoring very small glaciers in complex terrain, but both proved to be inappropriate; Sentinel-2 because of its too coarse horizontal resolution compared to the very small glaciers, and TanDEM-X-DEM because of errors in the steep summit area of Mt. Kenya. During 2004-2016, the total glacier area on Mt. Kenya decreased by 121.0 × 10 3 m 2 (44%). The largest glacier (Lewis) lost 62.8 × 10 3 m 2 (46%) of its area and 1.35 × 10 3 m 3 (57%) of its volume during the same period. The mass loss of Lewis Glacier has been accelerating since 2010 due to glacier disintegration, which has led to the emergence of a rock outcrop splitting the glacier in two parts. If the current retreat rates prevail, Mt. Kenya's glaciers will be extinct before 2030, implying the cessation of the longest glacier monitoring record of the tropics.

show abstract

Diagnosing the Droughts and Floods in Equatorial East Africa during Boreal Autumn 2005–08

Cited by 56 publications

References 15 publications

An analysis of recent rainfall conditions in eastern Africa

An analysis of recent rainfall conditions in eastern Africa

African hydroclimatic variability during the last 2000 years

Mapping the Loss of Mt. Kenya’s Glaciers: An Example of the Challenges of Satellite Monitoring of Very Small Glaciers

Contact Info

Product

Resources

About