Patterns of Indian Ocean sea-level change in a warming climate

Han, Weiqing; Meehl, Gerald A.; Rajagopalan, Balaji; Fasullo, John T.; Hu, Aixue; Lin, Jialin; Large, William G.; Wang, Jih-Wang; Quan, Xiao-Wei; Trenary, Laurie; Wallcraft, Alan J.; Shinoda, Toshiaki; Yeager, Stephen

doi:10.1038/ngeo901

Cited by 219 publications

(169 citation statements)

References 19 publications

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“…The characteristics of the background environment are however such as to place the flow close to the point where this bifurcation vanishes. There is evidence of a trend toward an intensification of the easterly trade winds over the southern Indian Ocean [Han et al, 2010;Rouault et al, 2009] and such changes would result in a decrease in the inverse Rossby number that may result in changes in the flow splitting by Madagascar.…”

Section: Discussionmentioning

confidence: 99%

Impact of the high topography of Madagascar on the structure of the Findlater Jet

Moore

2013

Geophysical Research Letters

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The cross‐equatorial flow over the western Indian Ocean, known as the Findlater Jet, plays an important role in the monsoonal circulation of the region. During the boreal summer, there is southerly flow across the equator that is concentrated along the East African highlands. During the boreal winter, there is a reversal in wind direction across the equator. Madagascar, the world's fourth largest island, with heights in excess of 1 km represents a significant obstacle to the flow whose impact on this jet has not been fully characterized. Here we use diagnostic tools developed to investigate atmospheric flow distortion by Greenland's high topography to study this interaction. We show that there is a bifurcation of the Findlater Jet by Madagascar during the boreal summer and localized tip jets at the island's northern and southern ends. During the boreal winter, the northern tip jet reverses direction and weakens, while the southern tip jet maintains its direction and magnitude. We show that rotational effects are important for these interactions but not dominant and result in an enhancement of the northern tip jet; while allowing for existence of the southern tip jet. As will also be shown, this flow distortion has impacts on the meteorology and oceanography of the region including the forcing of oceanic eddies in the Mozambique Channel, a modulation of the southward displacement of the Inter‐Tropical Convergence Zone (ITCZ) and a splitting of the boreal summer cross‐equatorial mass transport associated with the Findlater Jet into two branches.

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Section: Discussionmentioning

confidence: 99%

Impact of the high topography of Madagascar on the structure of the Findlater Jet

Moore

2013

Geophysical Research Letters

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“…Experiments using an OGCM and an atmospheric GCM (AGCM) show that surface winds associated with enhanced Indian Ocean Walker and Hadley circulations are the major force for this basin-wide pattern ( Fig. 7) (Han et al 2010). Variation of the Indonesian Throughflow may have a significant contribution to the thermocline cooling and thus sea level fall in the southwest tropical Indian Ocean (Schwarzkopf and Böning 2011), as shown by OGCM experiments forced with different reanalysis winds from that of [Han et al (2010); see Han et al (2014b) for a review].…”

Section: Forcing and Processesmentioning

confidence: 99%

“…2). While the multidecadal trends of surface winds associated with the changing Walker and Hadley circulations are shown to be partly forced by the Indian Ocean warming (Han et al 2010), which is attributed primarily to anthropogenic forcing since the 1950s (Du and Xie 2008;Dong et al 2014), they are suggested to have a large contribution from natural climate variability (Timmermann et al 2010). What natural climate modes account for the changes of Indian Ocean Walker and Hadley circulations, and what role does the changing Indian monsoon play?…”

Section: Forcing and Processesmentioning

confidence: 99%

“…Fig. 7b) (e.g., Han et al 2010;Timmermann et al 2010;Dunne et al 2012;NRC 2012). Experiments using an OGCM and an atmospheric GCM (AGCM) show that surface winds associated with enhanced Indian Ocean Walker and Hadley circulations are the major force for this basin-wide pattern ( Fig.…”

Section: Forcing and Processesmentioning

confidence: 99%

“…7) (Han et al 2010). Variation of the Indonesian Throughflow may have a significant contribution to the thermocline cooling and thus sea level fall in the southwest tropical Indian Ocean (Schwarzkopf and Böning 2011), as shown by OGCM experiments forced with different reanalysis winds from that of [Han et al (2010); see Han et al (2014b) for a review]. The ''basin-wide patterns'' of surface warming and thermocline cooling, however, are still mainly caused by Indian Ocean winds in the Schwarzkopf and Böning (2011) study (see their Fig.…”

Section: Forcing and Processesmentioning

confidence: 99%

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Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

et al. 2016

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Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth's climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modes and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this paper, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.

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Importance and origin of halosteric contribution to sea level change in the southeast Indian Ocean during 2005–2013

Llovel

Lee

2015

Geophysical Research Letters

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Steric sea level change has been identified as one of the major contributors to the regional variability of sea level trends observed by satellite altimetry for the past two decades. This contribution varies in space and time. The temperature (thermosteric) contribution to sea level has generally been found to be more important than the salinity (halosteric) effect. Based on sea level measurements from satellite altimetry and temperature and salinity data from Argo floats during 2005-2013, we found that the southeast Indian Ocean experiences a large halosteric contribution to sea level change. The conspicuously large halosteric contribution is associated with a freshening in the upper 300 m. Neither local atmospheric forcing such as Ekman pumping and E À P nor halosteric signal transmitted from the western tropical Pacific can explain this freshening. An enhanced precipitation in the Maritime Continent region and the observed strengthening of the Indonesian throughflow are the likely causes.

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Patterns of Indian Ocean sea-level change in a warming climate

Cited by 219 publications

References 19 publications

Impact of the high topography of Madagascar on the structure of the Findlater Jet

Impact of the high topography of Madagascar on the structure of the Findlater Jet

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

Importance and origin of halosteric contribution to sea level change in the southeast Indian Ocean during 2005–2013

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