Surface salinity advection in the tropical oceans compared with atmospheric freshwater forcing: A trial balance

被引:31
作者
Johnson, ES [1 ]
Lagerloef, GSE [1 ]
Gunn, JT [1 ]
Bonjean, F [1 ]
机构
[1] Earth & Space Res, Seattle, WA 98102 USA
关键词
tropics; observations; climatology; salinity budget; surface currents; surface forcing;
D O I
10.1029/2001JC001122
中图分类号
P7 [海洋学];
学科分类号
0707 ;
摘要
[1] Climatological surface salinities and satellite-derived surface currents are combined to estimate the horizontal and vertical time mean and seasonal salinity divergence in the tropical ocean's surface layer. The mean salinity divergence has magnitude and spatial patterns matching major features of an estimate of evaporation minus precipitation averaged from several atmospheric general circulation model reanalyses and satellite-derived products (spatial correlation of 0.63). Thus a substantial portion of the atmospheric freshwater flux appears to be balanced by ocean transports in a relatively thin (32.5 m) surface layer. Large regional discrepancies remain, however, and their magnitude is greater than the scatter among the various atmospheric forcing products used in this study. The present salinity divergence calculation is imprecise because the mean salinity gradients have been weakened by large-scale smoothing of sparse and unevenly sampled data. Further, other investigators show that higher-frequency ocean processes (e. g., vertical and horizontal mixing of salinity) are significant at least locally. Nevertheless, several areas of consistent disagreement between mean flow salinity divergence and atmospheric forcing, such as excess evaporation in subtropical gyres, are suggestive of errors in the forcing. In particular, the shortfall of salinity convergence balancing high precipitation in the western Pacific is roughly consistent with regional surface flux corrections required to bring ocean general circulation model integrations into long-term balance in this region. Thus this shortfall may reflect either overlarge precipitation estimates or a fundamental misunderstanding of how the ocean disperses this flux. Ultimately, further ocean physics must be addressed before firm conclusions can be drawn about the fraction of atmospheric freshwater input unaccounted for by the near-surface mean flow and seasonal salinity divergence. High-resolution space-based salinity measurements will be necessary to provide the temporal and spatial coverage necessary to develop ocean salinity transport calculations into useful constraints on ocean processes, surface hydrological forcing, and model simulations.
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页数:11
相关论文
共 41 条
[1]  
ARKIN PA, 1987, MON WEATHER REV, V115, P51, DOI 10.1175/1520-0493(1987)115<0051:TRBLSC>2.0.CO
[2]  
2
[3]  
Bendat J.S., 1971, RANDOM DATA ANAL MEA
[4]  
Bonjean F, 2002, J PHYS OCEANOGR, V32, P2938, DOI 10.1175/1520-0485(2002)032<2938:DMAAOT>2.0.CO
[5]  
2
[6]  
Caldwell DR, 1997, J PHYS OCEANOGR, V27, P1120, DOI 10.1175/1520-0485(1997)027<1120:TDARIT>2.0.CO
[7]  
2
[8]   Precipitation and sea-surface salinity in the tropical Pacific Ocean [J].
Delcroix, T ;
Henin, C ;
Porte, V ;
Arkin, P .
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 1996, 43 (07) :1123-1141
[9]   Sea surface salinity changes along the Fiji-Japan shipping track during the 1996 La Nina and 1997 El Nino period [J].
Delcroix, T ;
Gourdeau, L ;
Henin, C .
GEOPHYSICAL RESEARCH LETTERS, 1998, 25 (16) :3169-3172
[10]   SEASONAL AND INTERANNUAL VARIATIONS OF SEA-SURFACE SALINITY IN THE TROPICAL PACIFIC-OCEAN [J].
DELCROIX, T ;
HENIN, C .
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 1991, 96 (C12) :22135-22150