Analysis of teleconnections between AVHRR-based sea surface temperature and vegetation productivity in the semi-arid Sahel

Abstract Vegetation productivity across the Sahel is known to be affected by a variety of global sea surface temperature (SST) patterns. Often climate indices are used to relate Sahelian vegetation variability to large-scale ocean–atmosphere phenomena. However, previous research findings reporting on the Sahelian vegetation response to climate indices have been inconsistent and contradictory, which could partly be caused by the variations in spatial extent/definitions of climate indices and size of the region studied. The aim of this study was to analyze the linkage between climate indices, pixel-wise spatio-temporal patterns of global sea surface temperature and the Sahelian vegetation dynamics for 1982–2007. We stratified the Sahel into five subregions to account for the longitudinal variability in rainfall. We found significant correlations between climate indices and the Normalized Difference Vegetation Index (NDVI) in the Sahel, however with different magnitudes in terms of strength for the western, central and eastern Sahel. Also the correlations based on NDVI and global SST anomalies revealed the same East–West gradient, with a stronger association for the western than the eastern Sahel. Warmer than average SSTs throughout the Mediterranean basin seem to be associated with enhanced greenness over the central Sahel whereas colder than average SSTs in the Pacific and warmer than average SSTs in the eastern Atlantic were related to increased greenness in the most western Sahel. Accordingly, we achieved high correlations for SSTs of oceanic basins which are geographically associated to the climate indices yet by far not always these patterns were coherent. The detected SST–NDVI patterns could provide the basis to develop new means for improved forecasts in particular of the western Sahelian vegetation productivity.

[1]  Clara Deser,et al.  Surface Climate Variations over the North Atlantic Ocean during Winter: 1900–1989 , 1993 .

[2]  Lars Eklundh,et al.  Vegetation index trends for the African Sahel 1982–1999 , 2003 .

[3]  Abdou Ali,et al.  Recent trends in the Central and Western Sahel rainfall regime (1990–2007) , 2009 .

[4]  Sietse O. Los,et al.  Estimation of the ratio of sensor degradation between NOAA AVHRR channels 1 and 2 from monthly NDVI composites , 1998, IEEE Trans. Geosci. Remote. Sens..

[5]  S. Prince.  A model of regional primary production for use with coarse resolution satellite data , 1991 .

[6]  Nils Chr. Stenseth,et al.  Sub‐saharan desertification and productivity are linked to hemispheric climate variability , 2001 .

[7]  Guiling Wang.  Reassessing the impact of North Atlantic Oscillation on the sub‐Saharan vegetation productivity , 2003 .

[8]  Benjamin Smith,et al.  Precipitation controls Sahel greening trend , 2005 .

[9]  S. Nicholson,et al.  An Analysis of Recent Rainfall Conditions in West Africa, Including the Rainy Seasons of the 1997 El Nino and the 1998 La Nina Years , 2000 .

[10]  A. Sobel,et al.  SST Forcings and Sahel Rainfall Variability in Simulations of the Twentieth and Twenty-First Centuries , 2008 .

[11]  A. Herman,et al.  Objectively determined 10-day African rainfall estimates created for famine early warning systems , 1997 .

[12]  T. Palmer,et al.  Sahel rainfall and worldwide sea temperatures, 1901–85 , 1986, Nature.

[13]  J. Bader,et al.  Sahel rainfall and decadal to multi-decadal sea surface temperature variability , 2011 .

[14]  B. Holben.  Characteristics of maximum-value composite images from temporal AVHRR data , 1986 .

[15]  S. Nicholson,et al.  A comparison of the vegetation response to rainfall in the Sahel and East Africa, using normalized difference vegetation index from NOAA AVHRR , 1990 .

[16]  C. Tucker,et al.  Analysis of Sahelian vegetation dynamics using NOAA-AVHRR NDVI data from 1981–2003 , 2005 .

[17]  A. Anyamba,et al.  Interannual variability of NDVI over Africa and its relation to El Niño/Southern Oscillation , 1996 .

[18]  V. Moron,et al.  Guinean and sahelian rainfall anomaly indices at annual and monthly scales (1933–1990) , 1994 .

[19]  Rasmus Fensholt,et al.  Analysis of trends in the Sahelian `rain-use efficiency' using GIMMS NDVI, RFE and GPCP rainfall data , 2011 .

[20]  R. Saravanan,et al.  Oceanic Forcing of Sahel Rainfall on Interannual to Interdecadal Time Scales , 2003, Science.

[21]  T. Palmer.  Influence of the Atlantic, Pacific and Indian Oceans on Sahel rainfall , 1986, Nature.

[22]  K. Beurs,et al.  The response of African land surface phenology to large scale climate oscillations , 2010 .

[23]  Stephen D. Prince,et al.  Evidence from rain‐use efficiencies does not indicate extensive Sahelian desertification , 1998 .

[24]  Compton J. Tucker,et al.  Satellite remote sensing of total herbaceous biomass production in the Senegalese Sahel - 1980-1984 , 1985 .

[25]  A. Navarra,et al.  Teleconnections between Indian monsoon and Sahel rainfall and the Mediterranean , 2003 .

[26]  P. Mazzega,et al.  Dominant patterns of AVHRR NDVI interannual variability over the Sahel and linkages with key climate signals (1982–2003) , 2005 .

[27]  B. Goswami,et al.  A dipole mode in the tropical Indian Ocean , 1999, Nature.

[28]  D. Rowell.  The Impact of Mediterranean SSTs on the Sahelian Rainfall Season , 2003 .

[29]  Rasmus Fensholt,et al.  Water availability as the driver of vegetation dynamics in the African Sahel from 1982 to 2007 , 2011 .

[30]  Niall P. Hanan,et al.  ENSO and IOD teleconnections for African ecosystems: evidence of destructive interference between climate oscillations , 2010 .

[31]  Martin Kappas,et al.  Assessment of vegetation vulnerability to ENSO warm events over Africa , 2010, Int. J. Appl. Earth Obs. Geoinformation.

[32]  S. Kalluri,et al.  The Pathfinder AVHRR land data set: An improved coarse resolution data set for terrestrial monitoring , 1994 .

[33]  M. Ward,et al.  Diagnosis and Short-Lead Time Prediction of Summer Rainfall in Tropical North Africa at Interannual and Multidecadal Timescales , 1998 .

[34]  S. Prince.  Satellite remote sensing of primary production: comparison of results for Sahelian grasslands 1981-1988 , 1991 .

[35]  Jian Lu.  The dynamics of the Indian Ocean sea surface temperature forcing of Sahel drought , 2009 .

[36]  M. Jury,et al.  African climate variability in the satellite era , 2009 .

[37]  K. Wolter,et al.  Measuring the strength of ENSO events: How does 1997/98 rank? , 1998 .

[38]  Jonas Ardö,et al.  Disentangling the effects of climate and people on Sahel vegetation dynamics , 2008 .

[39]  Pierre Camberlin,et al.  Seasonality and atmospheric dynamics of the teleconnection between African rainfall and tropical sea‐surface temperature: Atlantic vs. ENSO , 2001 .

[40]  Compton J. Tucker,et al.  NDVI anomaly patterns over Africa during the 1997/98 ENSO warm event , 2001 .

[41]  M. Latif,et al.  The impact of decadal‐scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic Oscillation , 2003 .

[42]  E. Vermote,et al.  Absolute calibration of AVHRR visible and near-infrared channels using ocean and cloud views , 1995 .

[43]  V. Moron,et al.  West African Monsoon Dynamics and Eastern Equatorial Atlantic and Pacific SST Anomalies (1970-88) , 1998 .

[44]  J. Wallace,et al.  A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production , 1997 .

[45]  C. Tucker,et al.  Recent trends in vegetation dynamics in the African Sahel and their relationship to climate , 2005 .

[46]  Cyril Caminade,et al.  Twentieth century Sahel rainfall variability as simulated by the ARPEGE AGCM, and future changes , 2010 .

[47]  Thomas M. Smith,et al.  An Improved In Situ and Satellite SST Analysis for Climate , 2002 .

[48]  Benjamin W. Heumann,et al.  AVHRR Derived Phenological Change in the Sahel and Soudan, Africa, 1982 - 2005 , 2007 .

[49]  S. Hagos,et al.  Ocean Warming and Late-Twentieth-Century Sahel Drought and Recovery , 2008 .

[50]  J. Overpeck,et al.  Atlantic Forcing of Persistent Drought in West Africa , 2009, Science.

[51]  Nadège Martiny,et al.  Characterization of the Interannual and Intraseasonal Variability of West African Vegetation between 1982 and 2002 by Means of NOAA AVHRR NDVI Data , 2007 .

[52]  M. S. Rasmussen.  Assessment of millet yields and production in northern Burkina Faso using integrated NDVI from the AVHRR. , 1992 .

[53]  Edwin W. Pak,et al.  An extended AVHRR 8‐km NDVI dataset compatible with MODIS and SPOT vegetation NDVI data , 2005 .

[54]  D. L. Scarnecchia,et al.  The Grazing Land Ecosystems of the African Sahel , 1991 .

[55]  P. Lamb.  Large-scale Tropical Atlantic surface circulation patterns associated with Subsaharan weather anomalies , 1978 .

[56]  E. Lambin,et al.  Impact of ENSO on East African ecosystems: a multivariate analysis based on climate and remote sensing data , 2000 .