Spatial and temporal seasonal trends in coastal upwelling off Northwest Africa, 1981-2012

被引:181
作者
Cropper, Thomas E. [1 ]
Hanna, Edward [1 ]
Bigg, Grant R. [1 ]
机构
[1] Univ Sheffield, Dept Geog, Sheffield S10 2TN, S Yorkshire, England
关键词
Coastal upwelling; Africa; Wind; SST; Climate change; NAO; CLIMATE-CHANGE; CALIFORNIA CURRENT; EKMAN TRANSPORT; WIND SPEEDS; EL-NINO; REANALYSIS; SYSTEM; FUTURE; TEMPERATURE; VARIABILITY;
D O I
10.1016/j.dsr.2014.01.007
中图分类号
P7 [海洋学];
学科分类号
0707 ;
摘要
Seasonal coastal upwelling was analyzed along the NW African coastline (11-35 degrees N) from 1981 to 2012. Upwelling magnitudes are calculated by wind speed indices, sea-surface temperature indices and inferred from meteorological station, sea-surface height and vertical water column transport data. A permanent annual upwelling regime is documented across 21-35 degrees N and a seasonal regime across 12-19 degrees N, in accordance with the climatology of previous studies. Upwelling regions were split into three zones: (1) the Mauritania-Senegalese upwelling zone (12-19 degrees N), (2) the strong permanent annual upwelling zone (21-26 degrees N) and (3) the weak permanent upwelling zone (26-35 degrees N). We find compelling evidence in our various indices for the Bakun upwelling intensification hypothesis due to a significant coastal summer wind speed increase, resulting in an increase in upwelling-favorable wind speeds north of 20 degrees N and an increase in downwelling-favorable winds south of 20 degrees N. The North Atlantic Oscillation plays a leading role in modifying interannual variability during the other seasons (autumn-spring), with its influence dominating in winter. The East Atlantic pattern shows a strong correlation with upwelling during spring, while El Nino Southern Oscillation and Atlantic Multi-decadal Oscillation teleconnections were not found. A disagreement between observationally-based wind speed products and reanalysisderived data is explored. A modification to the Bakun upwelling intensification hypothesis for NW Africa is presented, which accounts for the latitudinal divide in summer wind regimes. (C) 2014 The Authors. Published by Elsevier Ltd.
引用
收藏
页码:94 / 111
页数:18
相关论文
共 89 条
[1]   A HOMOGENEITY TEST APPLIED TO PRECIPITATION DATA [J].
ALEXANDERSSON, H .
JOURNAL OF CLIMATOLOGY, 1986, 6 (06) :661-675
[2]  
An SI, 2001, J CLIMATE, V14, P2164, DOI 10.1175/1520-0442(2001)014<2164:MOLOTE>2.0.CO
[3]  
2
[4]  
[Anonymous], 2004, 8 S INTEGRATED OBSER
[5]  
[Anonymous], 1996, NOAA-TM-NMFS-SWFSC-231, Tech. Report
[6]   Sub-regional ecosystem variability in the Canary Current upwelling [J].
Aristegui, Javier ;
Barton, Eric D. ;
Alvarez-Salgado, Xose A. ;
Santos, A. Miguel P. ;
Figueiras, Francisco G. ;
Kifani, Souad ;
Hernandez-Leon, Santiago ;
Mason, Evan ;
Machu, Eric ;
Demarcq, Herve .
PROGRESS IN OCEANOGRAPHY, 2009, 83 (1-4) :33-48
[7]   GLOBAL CLIMATE CHANGE AND INTENSIFICATION OF COASTAL OCEAN UPWELLING [J].
BAKUN, A .
SCIENCE, 1990, 247 (4939) :198-201
[8]  
BAKUN A, 1992, ICES MAR SC, V195, P316
[9]   Seasonal patterns of wind-induced upwelling/downwelling in the Mediterranean Sea [J].
Bakun, A ;
Agostini, VN .
SCIENTIA MARINA, 2001, 65 (03) :243-257
[10]  
BAKUN A, 1991, J PHYS OCEANOGR, V21, P1815, DOI 10.1175/1520-0485(1991)021<1815:TSCOWS>2.0.CO