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The East African Monsoon System: Seasonal Climatologies and Recent Variations

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Abstract

This chapter briefly reviews the complex climatological cycle of the East African monsoon system, paying special attention to its connection to the larger Indo-Pacific-Asian monsoon cycle. We examine the seasonal monsoon cycle, and briefly explore recent circulation changes. The spatial footprint of our analysis corresponds with the “Greater Horn of Africa” (GHA) region, extending from Tanzania in the south to Yemen and Sudan in the north. During boreal winter, when northeast trade winds flow across the northwest Indian Ocean and the equatorial moisture transports over the Indian Ocean exhibit strong westerly mean flows over the equatorial Indian Ocean, East African precipitation is limited to a few highland areas. As the Indian monsoon circulation transitions during boreal spring, the trade winds over the northwest Indian Ocean reverse, and East African moisture convergence supports the “long” rains. In boreal summer, the southwesterly Somali Jet intensifies over eastern Africa. Subsidence forms along the westward flank of this jet, shutting down precipitation over eastern portions of East Africa. In boreal fall, the Jet subsides, but easterly moisture transports support rainfall in limited regions of the eastern Horn of Africa. We use regressions with the trend mode of global sea surface temperatures to explore potential changes in the seasonal monsoon circulations. Significant reductions in total precipitable water are indicated in Kenya, Tanzania, Rwanda, Burundi, Uganda, Ethiopia, South Sudan, Sudan, and Yemen, with moisture transports broadly responding in ways that reinforce the climatological moisture transports over the Indian Ocean. Over Kenya, southern Ethiopia and Somalia, regressions with velocity potential indicate increased convergence aloft. Near the surface, this convergence appears to manifest as a surface high pressure system that modifies moisture transports in these countries as well as Uganda, Tanzania, Rwanda, and Burundi. An analysis of rainfall changes indicates significant declines in parts of Tanzania, Rwanda, Burundi, Uganda, Kenya, Somalia, Ethiopia, and Yemen.

Keywords

  • East Africa monsoon system
  • Precipitation
  • CHIRPS

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References

  • Aristotle (350 B.C.) Meteorology

    Google Scholar 

  • Bjerknes J (1969) Atmospheric teleconnections from the equatorial Pacific. Mon Weather Rev 97:163–172

    CrossRef  Google Scholar 

  • Camberlin P (1995) June–September rainfall in North-Eastern Africa and atmospheric signals over the tropics: a zonal perspective. Int J Climatol 15:773–783

    CrossRef  Google Scholar 

  • Camberlin P, Philippon N (2002) The East African March–May rainy season: associated atmospheric dynamics and predictability over the 1968–97 period. J Clim 15:1002–1019

    CrossRef  Google Scholar 

  • Cane MA et al (1997) Twentieth-century sea surface temperature trends. Science 275:957–960

    CAS  CrossRef  Google Scholar 

  • Chadwick R, Boutle I, Martin G (2012) Spatial patterns of precipitation change in CMIP5: why the rich do not get richer in the tropics. J Clim 26:3803–3822

    CrossRef  Google Scholar 

  • Compo GP, Sardeshmukh PD (2010) Removing ENSO-related variations from the climate record. J Clim. doi:10.1175/2009JCLI2735.1, 1957–1978

    Google Scholar 

  • Cook KH, Vizy EK (2013) Projected Changes in East African rainy seasons. J Clim 26:5931–5948

    CrossRef  Google Scholar 

  • England MH et al (2014) Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus. Nat Clim Change

    Google Scholar 

  • Findlater J (1969) A major low-level air current near the Indian Ocean during the northern summer. Quart J R Meteorol Soc 95:362–380

    CrossRef  Google Scholar 

  • Funk C (2012) Exceptional warming in the Western Pacific-Indian Ocean warm pool has contributed to more frequent droughts in Eastern Africa. Bull Am Meteorol Soc 7:1049–1051

    Google Scholar 

  • Funk C, Michaelsen J, Marshall M (2012) Mapping recent decadal climate variations in precipitation and temperature across Eastern Africa and the Sahel. In: Wardlow B, Anderson M, Verdin J (eds) Remote sensing of drought: innovative monitoring approaches. CRC Press, p 25

    Google Scholar 

  • Funk C, Dettinger MD, Michaelsen JC, Verdin JP, Brown ME, Barlow M, Hoell A (2008) Warming of the Indian Ocean threatens eastern and southern African food security but could be mitigated by agricultural development. Proc Natl Acad Sci USA 105:11081–11086

    CAS  CrossRef  Google Scholar 

  • Funk C et al (2005) Recent drought tendencies in Ethiopia and equatorial-subtropical eastern Africa

    Google Scholar 

  • Funk C et al (2013) Attribution of 2012 and 2003–12 rainfall deficits in eastern Kenya and southern Somalia. Bull Am Meteorol Soc 94:45–48

    Google Scholar 

  • Funk C et al (2014) A quasi-global precipitation time series for drought monitoring 832, p 4

    Google Scholar 

  • Gill AE (1980) Some simple solutions for heat-induced tropical circulation. Quart J R Meteorol Soc 106:447–462

    CrossRef  Google Scholar 

  • Gill AE (1982) Atmosphere-ocean dynamics, vol 30. Academic Press, 662 pp

    Google Scholar 

  • Giese BS, Ray S (2011) El Niño variability in simple ocean data assimilation (SODA), 1871–2008. J Geophys Res Oceans 1978–2012:116

    Google Scholar 

  • Goddard L, Graham NE (1999) Importance of the Indian Ocean for simulating rainfall anomalies over eastern and southern Africa. J Geophys Res 104:19099–19116

    CrossRef  Google Scholar 

  • Hastenrath S, Polzin D, Mutai CC (2007) Diagnosing the 2005 drought in equatorial East Africa. J Clim 20:4628–4637

    CrossRef  Google Scholar 

  • Hastenrath S, Polzin D, Mutai C (2011) Circulation mechanisms of Kenya rainfall anomalies. J Clim 24:404–412

    CrossRef  Google Scholar 

  • Held IM, Soden BJ (2006) Robust responses of the hydrological cycle to global warming. J Clim 19:5686–5699

    CrossRef  Google Scholar 

  • Hoell A, Funk C (2013a) The ENSO-related West Pacific Sea surface temperature gradient. J Clim 26

    Google Scholar 

  • Hoell A, Funk C (2013b) Indo-Pacific sea surface temperature influences on failed consecutive rainy seasons over eastern Africa. Clim Dyn 1–16

    Google Scholar 

  • Hoell A, Funk C, Barlow M (2014) La Nina Diversity and the Forcing of Northwest Indian Ocean Rim Teleconnections. Clim Dyn

    Google Scholar 

  • Indeje M, Semazzi FH, Ogallo LJ (2000) ENSO signals in East African rainfall seasons. Int J Climatol 20:19–46

    CrossRef  Google Scholar 

  • IPCC (2014) Climate change 2014: impacts, adaptation, and vulnerability. Part B: regional aspects. Contribution of working Group II to the fifth assessment report of the intergovernmental panel on climate change. Cambridge University Press

    Google Scholar 

  • Kalnay E et al (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteorol Soc 77:437–471

    CrossRef  Google Scholar 

  • Krishnamurti TN, Molinari J, Pan HL (1976) Numerical simulation of the Somali jet. J Atmos Sci 33:2350–2362

    CrossRef  Google Scholar 

  • L’Heureux ML, Lee S, Lyon B (2013) Recent multidecadal strengthening of the Walker circulation across the tropical Pacific. Nat Clim Change

    Google Scholar 

  • Lyon B, DeWitt DG (2012) A recent and abrupt decline in the East African long rains. Geophys Res Lett 39(2). L02702

    Google Scholar 

  • Lyon B, Barnston AG, DeWitt DG (2013) Tropical pacific forcing of a 1998–1999 climate shift: observational analysis and climate model results for the boreal spring season. Clim Dyn 1–17

    Google Scholar 

  • Liebmann B et al (2012) Seasonality of African precipitation from 1996 to 2009. J Clim 25:4304–4322

    CrossRef  Google Scholar 

  • Liebmann B et al (2014) Understanding recent Eastern horn of Africa rainfall variability and change. J Clim (in press)

    Google Scholar 

  • Ogallo LJ, Janowiak JE, Halpert MS (1988) Teleconnection between seasonal rainfall over East Africa and global sea surface temperature anomalies. J Meteorol Soc Jpn 66:807–822

    CrossRef  Google Scholar 

  • Okoola RE (1999) A diagnostic study of the eastern Africa monsoon circulation during the Northern Hemisphere spring season. Int J Climatol 19:143–168

    CrossRef  Google Scholar 

  • Ramage C (1971) Monsoon meteorology, vol 296. Academic, San Diego

    Google Scholar 

  • Riddle EE, Cook KH (2008) Abrupt rainfall transitions over the greater horn of Africa: observations and regional model simulations. J Geophys Res Atmos 1984–2012:113

    Google Scholar 

  • Riehl H (1979) Climate and weather in the tropics. Academic Press, UK

    Google Scholar 

  • Rodwell MJ, Hoskins BJ (1996) Monsoons and the dynamics of deserts. Quart J R Meteorol Soc 122:1385–1404

    CrossRef  Google Scholar 

  • Rowell DP, Folland CK, Maskell K, Ward MN (1995) Variability of summer rainfall over tropical north Africa (1906–92): observations and modelling. Quart J R Meteorol Soc 121:669–704

    Google Scholar 

  • Saji NH, Goswami BN, Vinayachandran PN, Yamagata T (1999) A dipole mode in the tropical Indian Ocean. Nature 401:360–363

    CAS  Google Scholar 

  • Sandeep S, Stordal F, Sardeshmukh P, Compo G (2014) Pacific walker circulation variability in coupled and uncoupled climate models. Clim Dyn 43:103–117

    CrossRef  Google Scholar 

  • Schneider U, Becker A, Finger P, Meyer-Christoffer A, Ziese M, Rudolf B (2013) GPCC’s new land surface precipitation climatology based on quality-controlled in situ data and its role in quantifying the global water cycle. Theor Appl Climatol 1–26

    Google Scholar 

  • Shukla S, Funk C, Hoell A (2014) Using constructed analogs to improve the skill of March–April–May precipitation forecasts in equatorial East Africa. Environ Res Lett 9.9:094009

    Google Scholar 

  • Shukla S, McNally A, Husak G, Funk C (2014) A seasonal agricultural drought forecast system for food-insecure regions of East Africa. Hydrol Earth Syst Sc 18(10):3907-3921

    Google Scholar 

  • Smith TM, Reynolds RW, Peterson TC, Lawrimore J (2008) Improvements to NOAA’s historical merged land-ocean surface temperature analysis (1880–2006). J Clim 21:2283–2296

    CrossRef  Google Scholar 

  • Solomon A, Newman M (2012) Reconciling disparate twentieth-century Indo-Pacific ocean temperature trends in the instrumental record. Nat Clim Change 2:691–699

    CrossRef  Google Scholar 

  • Verdin J, Funk C, Senay G, Choularton R (2005) Climate science and famine early warning. Philos Trans R Soc B 360:2155–2168

    CrossRef  Google Scholar 

  • Viste E, Sorteberg A (2013) Moisture transport into the Ethiopian highlands. Int J Climatol 33:249–263

    CrossRef  Google Scholar 

  • Viste E, Korecha D, Sorteberg A (2012) Recent drought and precipitation tendencies in Ethiopia. Theor Appl Climatol 112:535–551

    CrossRef  Google Scholar 

  • Vizy EK, Cook KH (2003) Connections between the summer East African and Indian rainfall regimes. J Geophys Res Atmos 108:4510

    CrossRef  Google Scholar 

  • Walker GT (1923) Correlation in seasonal variations of weather, VIII. A Preliminary study of world weather. Memoirs of the Indian Meteorological Department

    Google Scholar 

  • Williams P, Funk C (2011) A westward extension of the warm pool leads to a westward extension of the walker circulation, drying eastern Africa. Clim Dyn

    Google Scholar 

  • Williams A et al (2011) Recent summer precipitation trends in the greater horn of Africa and the emerging role of Indian Ocean sea surface temperature. Clim Dyn 1–22

    Google Scholar 

  • Yang W, Seager R, Cane MA, Lyon B (2014) The East African long rains in observations and models. J Clim

    Google Scholar 

Download references

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Funk, C., Hoell, A., Shukla, S., Husak, G., Michaelsen, J. (2016). The East African Monsoon System: Seasonal Climatologies and Recent Variations. In: de Carvalho, L., Jones, C. (eds) The Monsoons and Climate Change. Springer Climate. Springer, Cham. https://doi.org/10.1007/978-3-319-21650-8_8

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