SMOS reveals the signature of Indian Ocean Dipole events
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The tropical Indian Ocean experiences an interannual mode of climatic variability, known as the Indian Ocean Dipole (IOD). The signature of this variability in ocean salinity is hypothesized based on modeling and assimilation studies, on account of scanty observations. Soil Moisture and Ocean Salinity (SMOS) satellite has been designed to take up the challenge of sea surface salinity remote sensing. We show that SMOS data can be used to infer the pattern of salinity variability linked with the IOD events. The core of maximum variability is located in the central tropical basin, south of the equator. This region is anomalously salty during the 2010 negative IOD event, and anomalously fresh during the 2011 positive IOD event. The peak-to-peak anomaly exceeds one salinity unit, between late 2010 and late 2011. In conjunction with other observational datasets, SMOS data allow us to draw the salt budget of the area. It turns out that the horizontal advection is the main driver of salinity anomalies. This finding is confirmed by the analysis of the outputs of a numerical model. This study shows that the advent of SMOS makes it feasible the quantitative assessment of the mechanisms of ocean surface salinity variability in the tropical basins, at interannual timescales.
KeywordsSSS Indian Ocean Dipole SMOS ARGO ENSO
Thermosalinograph data were collected and processed by the French SSS Observation Service (www.legos.obs-mip.fr/observations/sss). CNES partly funded these activities in the frame of the Centre Aval de Traitement des Données SMOS (CATDS) and of the SMOS TOSCA projects. The numerical model simulation was produced as part of the DRAKKAR project; we are grateful to Jean-Marc Molines and Bernard Barnier for their contribution. We are thankful to Thierry Delcroix and Clément de Boyer Montégut for fruitful discussions.
- Antonov JI, Locarnini RA, Boyer TP, Mishonov AV, Garcia HE (2006) World Ocean Atlas 2005, volume 2. In: Levitus S (ed) Salinity. NOAA Atlas NESDIS 62, U.S. Government Printing Office, Washington, D.C, p 182Google Scholar
- Boutin J, Martin N, Yin X, Reul N, Spurgeon P (2012) First assessment of SMOS data over open ocean: part II-sea surface salinity. IEEE Transactions on Geoscience and Remote Sensing, 50(5). Part 1:1662–1675Google Scholar
- Drakkar Group (2007) Eddy-permitting ocean circulation hindcasts of past decades. CLIVAR Exchanges 42 12(3):8–10Google Scholar
- Ferry N, Parent L, Garric G, Drevillon M, Desportes C, Bricaut C, Hernandez F (2011) Scientific validation report (ScVR) for V1 reprocessed analysis and reanalysis: GLORYS2V1. MyOcean FP7-SPACE-2007-1 project, report MYO-WP04-ScCV-rea-MERCATOR_V1RepGoogle Scholar
- Hasson A, Delcroix T, Dussin R (2013) An assessment of the mixed layer salinity budget in the tropical Pacific Ocean. Observations and modelling (1990–2009). Ocean Dyn 63(2–3):179–197. doi:10.1007/s10236-013-0596-2.
- Madec G (2008) NEMO reference manual, ocean dynamics component. Note du pôle de modélisation, IPSL, France No. 27 ISSN No. 1288–1619.Google Scholar
- Mecklenburg S, Kerr Y, Font J, Hahne A. (2008) The Soil Moisture and Ocean Salinity (SMOS) mission—an overview. Geophysical Research Abstracts, Vol. 10Google Scholar
- Mecklenburg S, Drusch M, Kerr YH, Font J, Martin-Neira M, Delwart S, Buenadicha G, Reul N, Daganzo-Eusebio E, Oliva R, Crapolicchio R (2012) ESA’s soil moisture and ocean salinity mission: mission performance and operations. IEEE Transactions on Geoscience and Remote Sensing 50(5). Part 1:1354–1366Google Scholar
- Reul N, Fournier S, Boutin J, Hernandez O, Maes C, Chapron B, Alory G, Quilfen Y, Tenerelli J, Morisset S, Kerr Y, Mecklenburg S, Delwart S (2013) Sea surface salinity observations from space with the SMOS satellite: a new means to monitor the marine branch of the water cycle. Surv Geophys. doi:10.1007/s10712-013-9244-0 Google Scholar
- Saji NH, Goswami BN, Vinayachandran PN, Yamagata T (1999) A dipole mode in the tropical Indian Ocean. Nature 401:360–363Google Scholar
- Vialard J, Delecluse P, Menkes C (2002) A modeling study of salinity variability and its effects in the tropical Pacific Ocean during the 1993–1999 period. J Geophys Res Oceans 107(C12). doi:10.1029/2000jc000758
- Yu L, Jin X, Weller R A (2008) Multidecade Global Flux Datasets from the Objectively Analyzed Air-sea Fluxes (OAFlux) Project: latent and sensible heat fluxes, ocean evaporation and related surface meteorological variables. Woods Hole Oceanographic Institution, OAFlux Project Technical Report. OA-2008-01, 64 pages. Woods Hole. Massachusetts.Google Scholar