Search Results

You are looking at 1 - 10 of 16 items for :

  • Indian Ocean Climate x
  • User-accessible content x
Clear All
Karumuri Ashok, Hisashi Nakamura, and Toshio Yamagata

intensity of the subtropical jet (STJ). In the absence of the developed STJ during austral summer, a single, well-defined circumpolar storm track forms along a deep polar-front (or subpolar) jet stream (PFJ). During austral winter, in contrast, the main upper-level storm track over the South Pacific forms along the intense STJ, while a low-level storm track with vigorous baroclinic eddy growth forms along the surface baroclinic zone off the Antarctic coast. Trapping upper-level eddy activity into its

Full access
Debasis Sengupta, Retish Senan, B. N. Goswami, and Jérôme Vialard

QuikSCAT winds, validated against available data, to study the basic dynamics of intraseasonal zonal current in the upper 200 m of the EqIO. Although the emphasis is on intraseasonal variability, we revisit some questions related to the dynamics of the seasonal cycle. a. Seasonal jets and undercurrents The Gan data showed that eastward equatorial jets ( Wyrtki 1973 ; Shenoi et al. 1999 ) accelerate to about 1 m s −1 when a westerly wind stress abruptly increases in spring and fall, but they

Full access
Suryachandra A. Rao, Sebastien Masson, Jing-Jia Luo, Swadhin K. Behera, and Toshio Yamagata

) compared to the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data. The model simulated a weak atmospheric Somali jet (Findlater jet) compared to the reanalysis data. Therefore, the upwelling along the coasts of Africa and Arabia is also weak and SSTs in those regions are relatively warm compared to the observations. The model precipitation distribution, in general, agrees very well with the observations both in July and in January. A relatively large precipitation total (2–4 mm

Full access
Tommy G. Jensen

jets During the spring and fall monsoon transition periods strong eastward surface jets appear along the equator ( Wyrtki 1973 ). Figure 12 shows the reversal of the zonal transport in the model solutions. For the climatology, the eastward transport is largest in the central part of the Indian Ocean during the fall jet. Between the spring and the fall eastward jets, westward flow is only found in the western Indian Ocean. For the La Niña case, the fall jet transport is increased due to longer

Full access
Vinu K. Valsala and Motoyoshi Ikeda

Currents ( Shetye et al. 1991 ), and Wyrtki Jet ( Wyrtki 1971 )] following the monsoon. These seasonal changes in circulation may be crucial in spreading the ITF in the northern Indian Ocean. The Somali Current is particularly the key to the ITF, which crosses the equator from the southern Indian Ocean to the northern region only in this western boundary current ( Schott et al. 2002 ; Miyama et al. 2003 ). Thus, the seasonally spreading pathways of the ITF have to be compared to its annual mean path

Full access
H. Annamalai, H. Okajima, and M. Watanabe

-hPa height response over the PNA region between the reanalysis and AGCM solutions reduces by about 15%–42% when the Indian Ocean effect is included with the Pacific. Linear model solutions reveal that Rossby waves excited by Indian Ocean heating do not follow the great circle, but are refracted toward the effective beta maximum associated with the Asian jet curvature. Further sensitivity experiments indicate that the zonally varying ambient flow is instrumental for the substantial PNA response to

Full access
Tommy G. Jensen

in the equatorial Indian Ocean show large intraseasonal variability of winds and currents on time scales of 10–60 days. The authors investigate the zonal momentum balance for currents and equatorial jets associated with this variability in an OGCM forced by Quick Scatterometer (QuikSCAT) winds. In the third paper in this group, Duvel and Vialard investigate the relations between intraseasonal variability of sea surface temperature, outgoing longwave radiation, heat flux, surface wind, and mixed

Full access
Rui-Jin Hu and J. Stuart Godfrey

—was built to create a crude analog of the heat budget of the region. The Ekman transport passed out through the open top 50 m of the southern boundary and was replaced by colder inflow through a full-depth “Indonesian gap.” A zonal jet from this gap fed a north-flowing western boundary current, which fed upwelling at the northern boundary. Diapycnal mixing did occur in this model; it was confined to the strongly sheared currents around an eddy in the northwest corner of the rectangular model domain

Full access
Tomoki Tozuka, Jing-Jia Luo, Sebastien Masson, and Toshio Yamagata

associated with the Indonesian Throughflow interestingly shows two positive peaks during year 0. The first peak is a result of the weaker spring Wyrtki jet at the initial stage of the IOD as discussed by Yamagata et al. (1996) and R. Suzuki et al. (2004, personal communication). The weaker spring Wyrtki jet results in the lower sea level in the eastern Indian Ocean, which enlarges the pressure gradient between the eastern Indian Ocean and the western Pacific, and thus increases the Indonesian

Full access
Qian Song, Gabriel A. Vecchi, and Anthony J. Rosati

seasons. The equatorial westerlies during the transition seasons—in both the model and observations—drive eastward-flowing Wyrtki (1973) jets (not shown). The modeled equatorial westerlies during the monsoon transition seasons are 1–2 m s −1 weaker than those in the ECMWF climatology; thus, the modeled Wyrtki jets are weaker than those estimated from ship drift and drifter data ( Cutler and Swallow 1984 ; Richardson and McKee 1989 ) by ∼5 cm s −1 . The annual mean equatorial zonal wind in the

Full access