Change in the association between Indian Ocean sea‐surface temperatures and summer rainfall over South Africa and Namibia

The El Nino–Southern Oscillation (ENSO) signal in Indian Ocean sea-surface temperatures has weakened since the late-1970s, resulting in important changes in the association between tropical western Indian Ocean sea-surface temperatures and December–February rainfall over South Africa and Namibia. Prior to the late-1970s, warm events in the tropical Indian Ocean occurred frequently in association with ENSO warm events, and both were typically associated with anomalously dry conditions over much of South Africa and Namibia. Over the most recent two decades, however, sea-surface temperature variability in the tropical western Indian Ocean has become significantly less dependent upon ENSO. At the same time, warm (cold) events in the tropical western Indian Ocean have become associated with wet (dry) conditions over the north-eastern half of South Africa and northern Namibia since the late-1970s. These changes in rainfall–sea-surface temperature associations can be successfully simulated using a general circulation model. Such changes in the climate system have important implications for the predictability of southern African rainfall, and highlight the need for an operational forecast system to predict Indian Ocean sea-surface temperatures. Copyright © 1999 Royal Meteorological Society

[1]  A. H. Thiessen.  PRECIPITATION AVERAGES FOR LARGE AREAS , 1911 .

[2]  Brian Everitt,et al.  Cluster analysis , 1974 .

[3]  D. Cadet.  The southern oscillation over the indian ocean , 1985 .

[4]  P. Handler.  Possible association between the climatic effects of stratospheric aerosols and sea surface temperatures in the Eastern tropical Pacific Ocean , 1986 .

[5]  M. Richman,et al.  Rotation of principal components , 1986 .

[6]  Dara Entekhabi,et al.  Rainfall Variability in Equatorial and Southern Africa: Relationships with Sea Surface Temperatures along the Southwestern Coast of Africa , 1987 .

[7]  H. Flohn.  Air-Sea Interaction Processes as Models for Abrupt Climatic Changes , 1987 .

[8]  Richard W. Reynolds,et al.  A Real-Time Global Sea Surface Temperature Analysis , 1988 .

[9]  R. Preisendorfer,et al.  Principal Component Analysis in Meteorology and Oceanography , 1988 .

[10]  N. Walker.  Links between South African summer rainfall and temperature variability of the Agulhas and Benguela Current systems , 1990 .

[11]  Kevin E. Trenberth,et al.  Recent Observed Interdecadal Climate Changes in the Northern Hemisphere , 1990 .

[12]  J. E. Jackson.  A User's Guide to Principal Components , 1991 .

[13]  M. Jury,et al.  A study of climate and weather variability over the tropical southwest Indian Ocean , 1991 .

[14]  A. Barnston,et al.  Prediction of ENSO Episodes Using Canonical Correlation Analysis , 1992 .

[15]  R A Kerr,et al.  Unmasking a shifty climate system. , 1992, Science.

[16]  L. Greischar,et al.  Atmospheric-hydrospheric mechanisms of climate anomalies in the western equatorial Indian Ocean , 1993 .

[17]  M. Jury,et al.  Influence of the Agulhas Current on Summer Rainfall along the Southeast Coast of South Africa , 1993 .

[18]  J. Lindesay,et al.  Water vapour transport over Southern Africa during wet and dry early and late summer months , 1993 .

[19]  G. Meehl.  A Coupled Air-Sea Biennial Mechanism in the Tropical Indian and Pacific Regions: Role of the Ocean , 1993 .

[20]  N. Graham.  Decadal-scale climate variability in the tropical and North Pacific during the 1970s and 1980s: observations and model results , 1994 .

[21]  Ryuichi Kawamura,et al.  A rotated EOF analysis of global sea surface temperature variability with interannual and interdecadal scales , 1994 .

[22]  Peter Tyson,et al.  Simulating drought in Southern Africa using sea surface temperature variations , 1994 .

[23]  Thomas M. Smith,et al.  Improved Global Sea Surface Temperature Analyses Using Optimum Interpolation , 1994 .

[24]  Mojib Latif,et al.  Climate Variability in a Coupled GCM. Part II: The Indian Ocean and Monsoon , 1994 .

[25]  P. Tyson,et al.  Divergent and non-divergent water vapour transport over southern Africa during wet and dry conditions , 1995 .

[26]  C. Reason,et al.  Multidecadal Variability in the Climate System over the Indian Ocean Region during the Austral Summer. , 1995 .

[27]  Bin Wang,et al.  Interdecadal changes in El Niño onset in the last four decades , 1995 .

[28]  Mojib Latif,et al.  Interactions of the Tropical Oceans , 1995 .

[29]  Coupled atmosphere-ocean model simulations of El Nino/Southern Oscillation with and without an active Indian Ocean , 1995 .

[30]  H. Storch,et al.  Analysis of Climate Variability , 1995 .

[31]  Simon J. Mason,et al.  Sea-surface temperature — South African rainfall associations, 1910–1989 , 1995 .

[32]  D. Parker,et al.  Marine surface temperature: Observed variations and data requirements , 1995 .

[33]  N. Graham,et al.  Simulation of Recent Global Temperature Trends , 1995, Science.

[34]  John M. Wallace,et al.  ENSO seasonality : 1950-78 versus 1979-92 , 1996 .

[35]  Three-dimensional kinematic trajectory modelling of water vapour transport over Southern Africa , 1996 .

[36]  M. Hulme.  Recent climatic change in the world`s drylands , 1996 .

[37]  Mark R. Jury,et al.  Drought over South Africa and Indian Ocean SST : Statistical and GCM results , 1996 .

[38]  INFLUENCE OF INDIAN OCEAN SEA-SURFACE TEMPERATURE ANOMALIES ON THE GENERALCIRCULATION OF SOUTHERN AFRICA , 1996 .

[39]  Timothy J. Hoar,et al.  The 1990–1995 El Niño‐Southern Oscillation Event: Longest on Record , 1996 .

[40]  M. Jury,et al.  Predictability of Zimbabwe summer rainfall , 1997 .

[41]  Ian Simmonds,et al.  INTERANNUAL VARIABILITY OF SOUTH‐EASTERN AFRICAN SUMMER RAINFALL. PART 1: RELATIONSHIPS WITH AIR–SEA INTERACTION PROCESSES , 1997 .

[42]  Sharon E. Nicholson,et al.  Correction: An analysis of the ENSO signal in the tropical Atlantic and Western Indian oceans , 1997 .

[43]  Simon J. Mason,et al.  Climatic variability and change over southern Africa: a reflection on underlying processes , 1997 .

[44]  Simon J. Mason,et al.  Seasonal forecasting of South African rainfall using a non‒linear discriminant analysis model , 1998 .

[45]  Willem A. Landman,et al.  Operational long‐lead prediction of South African rainfall using canonical correlation analysis , 1999 .

[46]  S. Mason,et al.  The Extreme Precipitation Event of 11 to 16 February 1996 over South Africa , 1999 .

[47]  N. Graham,et al.  Importance of the Indian Ocean for simulating rainfall anomalies over eastern and southern Africa , 1999 .

[48]  S. Mason,et al.  The occurrence and predictability of droughts over southern Africa. , 2000 .