Skip to main content

Advertisement

SpringerLink
Log in

Atmospheric teleconnection mechanisms of extratropical North Atlantic SST influence on Sahel rainfall

  • Published:
Climate Dynamics Aims and scope Submit manuscript

Abstract

Extratropical North Atlantic cooling has been tied to droughts over the Sahel in both paleoclimate observations and modeling studies. This study, which uses an atmospheric general circulation model (GCM) coupled to a slab ocean model that simulates this connection, explores the hypothesis that the extratropical North Atlantic cooling causes the Sahel droughts via an atmospheric teleconnection mediated by tropospheric cooling. The drying is also produced in a regional climate model simulation of the Sahel when reductions in air temperature (and associated geopotential height and humidity changes) from the GCM simulation are imposed as the lateral boundary conditions. This latter simulation explicitly demonstrates the central role of tropospheric cooling in mediating the atmospheric teleconnection from extratropical North Atlantic cooling. Diagnostic analyses are applied to the GCM simulation to infer teleconnection mechanisms. An analysis of top of atmosphere radiative flux changes diagnosed with a radiative kernel technique shows that extratropical North Atlantic cooling is augmented by a positive low cloud feedback and advected downstream, cooling Europe and North Africa. The cooling over North Africa is further amplified by a reduced greenhouse effect from decreased atmospheric specific humidity. A moisture budget analysis shows that the direct moisture effect and monsoon weakening, both tied to the ambient cooling and resulting circulation changes, and feedbacks by vertical circulation and evaporation augment the rainfall reduction. Cooling over the Tropical North Atlantic in response to the prescribed extratropical cooling also augments the Sahel drying. Taken together, they suggest a thermodynamic pathway for the teleconnection. The teleconnection may also be applicable to understanding the North Atlantic influence on Sahel rainfall over the twentieth century.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8

Similar content being viewed by others

References

  • Adler RF, Huffman GJ, Chang A et al (2003) The version-2 global precipitation climatology project (GPCP) monthly precipitation analysis (1979-present). J Hydrometeorol 4:1147–1167. doi:10.1175/1525-7541(2003)004<1147:TVGPCP>2.0.CO;2

    Article  Google Scholar 

  • Alley RB (2007) Wally was right: predictive ability of the North Atlantic “conveyor belt” hypothesis for abrupt climate change. Annu Rev Earth Planet Sci 35:241–272

    Article  Google Scholar 

  • Bader J, Latif M (2003) The impact of decadal-scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic Oscillation. Geophys Res Lett 30:2169

    Article  Google Scholar 

  • Biasutti M, Giannini A (2006) Robust Sahel drying in response to late 20th century forcings. Geophys Res Lett 33:L11706. doi:10.1029/2006GL026067

  • Biasutti M, Sobel A, Camargo S (2009) The role of the Sahara low in summertime Sahel rainfall variability and change in the CMIP3 models. J Clim 22:5755–5771. doi:10.1175/2009JCLI2969.1

    Article  Google Scholar 

  • Broecker WS, Peteet DM, Rind D (1985) Does the ocean–atmosphere system have more than one stable mode of operation? Nature 315:21–26. doi:10.1038/315021a0

    Article  Google Scholar 

  • Chen H, Zhou T, Neale R, Wu X, Zhang G (2010) Performance of the new NCAR CAM3. 5 in East Asian summer monsoon simulations: sensitivity to modifications of the convection scheme. J Clim 23:3657–3675

    Article  Google Scholar 

  • Cheng W, Bitz CM, Chiang JCH (2007) Adjustment of the global climate to an abrupt slowdown of the Atlantic meridional overturning circulation. Geophys Monogr 173:295

    Google Scholar 

  • Chiang JCH, Bitz CM (2005) Influence of high latitude ice cover on the marine intertropical convergence zone. Clim Dyn 25:477–496

    Article  Google Scholar 

  • Chiang JCH, Friedman AR (2012) Extratropical cooling, interhemispheric thermal gradients, and tropical climate change. Annu Rev Earth Planet Sci 40(40):383–412

    Article  Google Scholar 

  • Chou C, Neelin JD (2004) Mechanisms of global warming impacts on regional tropical precipitation. J Clim 17:2688–2701. doi:10.1175/1520-0442(2004)017<2688:MOGWIO>2.0.CO;2

    Article  Google Scholar 

  • Chou C, Neelin J, Su H (2001) Ocean–atmosphere–land feedbacks in an idealized monsoon. Q J R Meteorol Soc 127:1869–1891. doi:10.1002/qj.49712757602

    Article  Google Scholar 

  • Chou C, Neelin JD, Chen C-A, Tu J-Y (2009) Evaluating the “Rich-Get-Richer” mechanism in tropical precipitation change under global warming. J Clim 22:1982–2005. doi:10.1175/2008JCLI2471.1

    Article  Google Scholar 

  • Collins W, Rasch P, Boville B et al (2006) The formulation and atmospheric simulation of the Community Atmosphere Model version 3 (CAM3). J Clim 19:2144–2161

    Article  Google Scholar 

  • Cook K (1999) Generation of the African easterly jet and its role in determining West African precipitation RID B-4998-2011. J Clim 12:1165–1184. doi:10.1175/1520-0442(1999)012<1165:GOTAEJ>2.0.CO;2

    Article  Google Scholar 

  • Folland CK, Palmer TN, Parker DE (1986) Sahel rainfall and worldwide sea temperatures, 1901–85. Nature 320:602–607

    Article  Google Scholar 

  • Folland CK, Owen J, Ward MN, Colman A (1991) Prediction of seasonal rainfall in the Sahel region using empirical and dynamic methods. J Forecast 10:21–56. doi:10.1002/for.3980100104

    Article  Google Scholar 

  • Fontaine B, Trzaska S, Janicot S (1998) Evolution of the relationship between near global and Atlantic SST modes and the rainy season in West Africa: statistical analyses and sensitivity experiments. Clim Dyn 14:353–368. doi:10.1007/s003820050228

    Article  Google Scholar 

  • Giannini A, Saravanan R, Chang P (2003) Oceanic forcing of Sahel rainfall on interannual to interdecadal time scales. Science 302:1027–1030

    Article  Google Scholar 

  • Grist J, Nicholson S (2001) A study of the dynamic factors influencing the rainfall variability in the West African Sahel. J Clim 14(7):1337–1359

    Article  Google Scholar 

  • Haarsma RJ, Selten FM, Weber SL, Kliphuis M (2005) Sahel rainfall variability and response to greenhouse warming. Geophys Res Lett 32:L17702

    Article  Google Scholar 

  • Held IM, Delworth TL, Lu J et al (2006) Simulation of Sahel drought in the 20th and 21st centuries. Natl Acad Sci U S A 103(4):1152–1153

    Article  Google Scholar 

  • Hoerling M, Hurrell J, Eischeid J, Phillips A (2006) Detection and attribution of twentieth-century northern and southern African rainfall change. J Clim 19(16):3989–4008

    Article  Google Scholar 

  • Janjic Z (1994) The step-mountain Eta coordinate model—further developments of the convection, viscous sublayer, and turbulence closure schemes. Mon Weather Rev 122:927–945. doi:10.1175/1520-0493(1994)122<0927:TSMECM>2.0.CO;2

    Article  Google Scholar 

  • Janjic Z (1996) The surface layer in the NCEP Eta model. In: Eleventh conference on numerical weather prediction, Norfolk, VA, 19–23 August. Am Meteor Soc, Boston, MA, pp 354–355

  • Janjic ZI (2002) Nonsingular implementation of the Mellor–Yamada level 2.5 scheme in the NCEP Meso model. NCEP Office Note 437:61

    Google Scholar 

  • Kalnay E, Kanamitsu M, Kistler R et al (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteor Soc 77:437–471

    Article  Google Scholar 

  • Kanamitsu M, Ebisuzaki W, Woollen J et al (2002) NCEP-DOE AMIP-II Reanalysis (R-2). Bull Am Meteorol Soc 83:1631–1644

    Article  Google Scholar 

  • Kawase H, Abe M, Yamada Y et al (2010) Physical mechanism of long-term drying trend over tropical North Africa. Geophys Res Lett 37:L09706

    Google Scholar 

  • Lin Y, Farley R, Orville H (1983) Bulk parameterization of the snow field in a cloud model. J Clim Appl Meteorol 22:1065–1092. doi:10.1175/1520-0450(1983)022<1065:BPOTSF>2.0.CO;2

    Article  Google Scholar 

  • Liu Y, Chiang JCH (2012) Coordinated abrupt weakening of the Eurasian and North African Monsoons in the 1960s and links to extratropical North Atlantic cooling. J Clim 25:3532–3548. doi:10.1175/JCLI-D-11-00219.1

    Article  Google Scholar 

  • Mlawer EJ, Taubman SJ, Brown PD et al (1997) Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave. J Geophys Res Atmos 102:16663–16682. doi:10.1029/97JD00237

    Article  Google Scholar 

  • Monin AS, Obukhov AM (1954) Basic laws of turbulent mixing in the surface layer of the atmosphere. Contrib Geophys Inst Acad Sci USSR 151:163–187

    Google Scholar 

  • Mulitza S, Prange M, Stuut JB et al (2008) Sahel mega droughts triggered by glacial slowdowns of Atlantic meridional overturning. Paleoceanography. doi:10.1029/2008PA001637

    Google Scholar 

  • Nicholson S (1979) Revised rainfall series for the West-African Subtropics. Mon Weather Rev 107:620–623. doi:10.1175/1520-0493(1979)107<0620:RRSFTW>2.0.CO;2

    Article  Google Scholar 

  • Nicholson S (2009) On the factors modulating the intensity of the tropical rainbelt over West Africa. Int J Clim 29:673–689. doi:10.1002/joc.1702

    Article  Google Scholar 

  • Niedermeyer EM, Prange M, Mulitza S et al (2009) Extratropical forcing of Sahel aridity during Heinrich stadials. Geophys Res Lett. doi:10.1029/2009GL039687

    Google Scholar 

  • Patricola CM, Cook KH (2008) Atmosphere/vegetation feedbacks: a mechanism for abrupt climate change over northern Africa. J Geophys Res Atmos. doi:10.1029/2007JD009608

    Google Scholar 

  • Patricola CM, Cook KH (2010) Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models. Clim Dyn 35:193–212. doi:10.1007/s00382-009-0623-7

    Article  Google Scholar 

  • Rotstayn LD, Lohmann U (2002) Tropical rainfall trends and the indirect aerosol effect. J Clim 15(15):2103–2116

    Article  Google Scholar 

  • Rowell DP, Folland CK, Maskell K, Ward MN (1995) Variability of summer rainfall over tropical north-Africa (1906–92) observations and modeling. Q J R Meteorol Soc 121:669–704. doi:10.1256/smsqj.52310

    Google Scholar 

  • Shanahan T, Overpeck J, Anchukaitis K et al (2009) Atlantic forcing of persistent drought in West Africa. Science 324:377–380. doi:10.1126/science.1166352

    Article  Google Scholar 

  • Shell K, Kiehl J, Shields C (2008) Using the radiative kernel technique to calculate climate feedbacks in NCAR’s Community Atmospheric Model. J Clim 21:2269–2282. doi:10.1175/2007JCLI2044.1

    Article  Google Scholar 

  • Skamarock WC, Klemp JB, Dudhia J et al (2008) A description of the advanced research WRF Version 3. NCAR/TN-475+STR

  • Smirnova TG, Brown JM, Benjamin SG (1997) Performance of different soil model configurations in simulating ground surface temperature and surface fluxes. Mon Weather Rev 125:1870–1884. doi:10.1175/1520-0493(1997)125<1870:PODSMC>2.0.CO;2

    Article  Google Scholar 

  • Soden B, Held I, Colman R et al (2008) Quantifying climate feedbacks using radiative kernels. J Clim 21:3504–3520. doi:10.1175/2007JCLI2110.1

    Article  Google Scholar 

  • Stager J, Ryves D, Chase B, Pausata F (2011) Catastrophic drought in the Afro-Asian monsoon region during Heinrich event 1. Science 331:1299–1302. doi:10.1126/science.1198322

    Article  Google Scholar 

  • van Kreveld S, Sarnthein M, Erlenkeuser H et al (2000) Potential links between surging ice sheets, circulation changes, and the Dansgaard–Oeschger cycles in the Irminger Sea, 60-18 kyr. Paleoceanography 15:425–442. doi:10.1029/1999PA000464

    Article  Google Scholar 

  • Vellinga M, Wood R (2002) Global climatic impacts of a collapse of the Atlantic thermohaline circulation. Clim Change 54:251–267. doi:10.1023/A:1016168827653

    Article  Google Scholar 

  • Wang Y, Cheng H, Edwards R et al (2001) A high-resolution absolute-dated Late Pleistocene monsoon record from Hulu Cave, China. Science 294:2345–2348

    Article  Google Scholar 

  • Xue Y, Jagadish S (1993) The influence of land surface properties on Sahel climate. Part 1: desertification. J Clim 6(12):2232–2245

    Article  Google Scholar 

  • Zhang R, Delworth TL (2005) Simulated tropical response to a substantial weakening of the Atlantic thermohaline circulation. J Clim 18:1853–1860

    Article  Google Scholar 

  • Zhang G, Mcfarlane N (1995) Sensitivity of climate simulations to the parameterization of cumulus convection in the Canadian Climate Center general-circulation model. Atmos Ocean 33:407–446

    Article  Google Scholar 

  • Zhou T, Yu R, Li H, Wang B (2008) Ocean forcing to changes in global monsoon precipitation over the recent half-century. J Clim 21:3833–3852

    Article  Google Scholar 

Download references

Acknowledgments

This research is supported by the National Science Foundation (NSF AGS-1143329 and NSF EAR-0909195). The authors would like to thank Inez Fung, Shih-Yu Lee, Andrew Friedman and Ching-Yee Chang for useful and enlightening discussions. YL thanks Ivana Cvijanovic for helping design the GCM simulation, Alexandra Jonko for assistance with using the radiative kernel technique, Andrew Friedman and Meghan Thurlow for editing the manuscript for grammar and usage. All reanalysis data are provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, at http://www.esrl.noaa.gov/psd/.

Author information

Authors and Affiliations

  1. Department of Geography, University of California, 531 McCone Hall, Berkeley, CA, 94720, USA

    Yuwei Liu & John C. H. Chiang

  2. Berkeley Center for Atmospheric Sciences, University of California, Berkeley, CA, USA

    John C. H. Chiang

  3. Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan

    Chia Chou

  4. Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan

    Chia Chou

  5. Department of Atmospheric Sciences, Texas A&M University, College Station, TX, USA

    Christina M. Patricola

Authors
  1. Yuwei Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. John C. H. Chiang
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Chia Chou
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Christina M. Patricola
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Yuwei Liu.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Liu, Y., Chiang, J.C.H., Chou, C. et al. Atmospheric teleconnection mechanisms of extratropical North Atlantic SST influence on Sahel rainfall. Clim Dyn 43, 2797–2811 (2014). https://doi.org/10.1007/s00382-014-2094-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00382-014-2094-8

Keywords

Search

Navigation