Observed intraseasonal variability of mini‐cold pool off the southern tip of India and its intrusion into the south central Bay of Bengal during summer monsoon season

Rao, R. R.; Girishkumar, M. S.; Ravichandran, M.; Samala, Basanta Kumar; Anitha, G.

doi:10.1029/2006gl026086

Cited by 27 publications

(19 citation statements)

References 8 publications

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“…Furthermore, the cold pool in the southern Bay of Bengal (Joseph et al 2005;Rao et al 2006aRao et al , 2006b) and its restriction to the western half of the southern bay , which is in accordance with satellite measurements, is evident in the NIOA seasonal climatology for the summer monsoon. This restriction of the cold pool to the southwestern bay is in accordance with satellite measurements of SST .…”

Section: Fall Intermonsoon: October-novembersupporting

confidence: 74%

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A new atlas of temperature and salinity for the North Indian Ocean

et al. 2012

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The most used temperature and salinity climatology for the world ocean, including the Indian Ocean, is the World Ocean Atlas (WOA) Locarnini et al 2006Locarnini et al , 2010 because of the vast amount of data used in its preparation. The WOA climatology does not, however, include all the available hydrographic data from the Indian Exclusive Economic Zone (EEZ), leading to the potential for improvement if the data from this region are included to prepare a new climatology. We use all the data that went into the preparation of the WOA (Antonov et al 2010; Locarnini et al 2010), but add considerable data from Indian sources, to prepare new annual, seasonal, and monthly climatologies of temperature and salinity for the Indian Ocean. The addition of data improves the climatology considerably in the Indian EEZ, the differences between the new North Indian Ocean Atlas (NIOA) and WOA being most significant in the Bay of Bengal, where the patchiness seen in WOA, an artifact of the sparsity of data, was eliminated in NIOA. The significance of the new climatology is that it presents a more stable climatological value for the temperature and salinity fields in the Indian EEZ.

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Section: Fall Intermonsoon: October-novembersupporting

confidence: 74%

“…The cold pool starts strengthening from June, and reaches its peak in August. The cold pool (Joseph et al 2005), which is a result of the eastward advection of the cold waters into the southern bay Rao et al 2006aRao et al , 2006b), did not extend as far east as in WOA09.…”

Section: Surface Temperaturementioning

confidence: 98%

A new atlas of temperature and salinity for the North Indian Ocean

et al. 2012

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“…Notwithstanding the larger solar heating of the surface due to less cloudiness, the "pool" region is able to maintain low SST compared to the largely cloudy regions at its surroundings. This shows that, in addition to the contribution from the spreading of cold waters from STI (Rao et al, 2006), the cold SST at the "pool" might also be driven by the ocean upwelling caused by the surface wind divergence associated with the mini-circulation described above (Fig. 4b).…”

Section: Resultsmentioning

confidence: 85%

“…It shows a cold tongue originating off the southern tip of India (STI) and extending up to the south central BoB. This cold tongue (Joseph et al, 2005) arises from the ocean upwelling caused by the prevailing surface wind and its eastward spreading by the summer monsoon current into the BoB (Rao et al, 2006). However, the cold tongue has significantly large eastward extension than the "pool", while the latter extends farther to the north compared to the former.…”

Section: Resultsmentioning

confidence: 99%

Characteristics of a persistent "pool of inhibited cloudiness" and its genesis over the Bay of Bengal associated with the Asian summer monsoon

et al. 2011

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Abstract. Using spatial and vertical distributions of clouds derived from multi-year spaceborne observations, this paper presents the characteristics of a significant "pool of inhibited cloudiness" covering an area of >10 6 km 2 between 3-13 • N and 77-90 • E over the Bay of Bengal (BoB), persisting throughout the Asian summer monsoon season (ASM). Seasonal mean precipitation rate over the "pool" is <3 mm day −1 while that over the surrounding regions is mostly in the range of 6-14 mm day −1 . Frequency of occurrence of clouds in this "pool" is ∼20-40 % less than that over the surrounding deep convective regions. Zonal and meridional cross sections of the altitude distribution of clouds derived from CloudSat data reveal a vault-like structure at the "pool" with little cloudiness below ∼7 km, indicating that this "pool" is almost fully contributed by the substantially reduced or near-absence of low-and middle-level clouds. This suggest the absence of convection in the "pool" region. Spaceborne scatterometer observations show divergence of surface wind at the "pool" and convergence at its surroundings, suggesting the existence of a mini-circulation embedded in the large-scale monsoon circulation. Reanalysis data shows a mini-circulation extending between the surface and ∼3 km altitude, but its spatial structure does not match well with that inferred from the above observations. Sea surface at the south BoB during ASM is sufficiently warm to trigger convection, but is inhibited by the subsidence associated with the mini-circulation, resulting in the "pool". This minicirculation might be a dynamical response of the atmosphere to the substantial spatial gradient of latent heating by largescale cloudiness and precipitation at the vast and geographically fixed convective zones surrounding the "pool". Subsidence at the "pool" might contribute to the maintenance of convection at the above zones and be an important component of ASM that is overlooked hitherto.Correspondence to: K. Rajeev (k rajeev@vssc.gov.in)

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“…As wind is meridional in both the seasons, Ekman mass transport will be westward along most part of coast line. One noticeable fact is that the wind field near southern tip of India is divergent for both the seasons (Luis & Kawamura 2000Rao et al 2006aRao et al , 2006b. Climatological wind speed along the southwest coast of India during southwest monsoon is within the range of 5 to 6 m/s and in northeast monsoon it is 2 to 3 m/s.…”

Section: Ekman Upwelling Indexmentioning

confidence: 99%

Interannual variability of upwelling indices in the Southeastern Arabian Sea: A satellite based study

et al. 2010

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Increase in sea surface temperature with global warming has an impact on coastal upwelling. Past two decades (1988 to 2007) of satellite observed sea surface temperatures and space borne scatterometer measured winds have provided an insight into the dynamics of coastal upwelling in the southeastern Arabian Sea, in the global warming scenario. These high resolution data products have shown inconsistent variability with a rapid rise in sea surface temperature between 1992 and 1998 and again from 2004 to 2007. The upwelling indices derived from both sea surface temperature and wind have shown that there is an increase in the intensity of upwelling during the period 1998 to 2004 than the previous decade. These indices have been modulated by the extreme climatic events like El-Nino and Indian Ocean Dipole that happened during 1991-92 and 1997-98. A considerable drop in the intensity of upwelling was observed concurrent with these events. Apart from the impact of global warming on the upwelling, the present study also provides an insight into spatial variability of upwelling along the coast. Noticeable fact is that the intensity of offshore Ekman transport off 8 o N during the winter monsoon is as high as that during the usual upwelling season in summer monsoon. A drop in the meridional wind speed during the years 2005, 2006 and 2007 has resulted in extreme decrease in upwelling though the zonal wind and the total wind magnitude are a notch higher than the previous years. This decrease in upwelling strength has resulted in reduced productivity too.

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Observed intraseasonal variability of mini‐cold pool off the southern tip of India and its intrusion into the south central Bay of Bengal during summer monsoon season

Cited by 27 publications

References 8 publications

A new atlas of temperature and salinity for the North Indian Ocean

A new atlas of temperature and salinity for the North Indian Ocean

Characteristics of a persistent "pool of inhibited cloudiness" and its genesis over the Bay of Bengal associated with the Asian summer monsoon

Interannual variability of upwelling indices in the Southeastern Arabian Sea: A satellite based study

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Observed intraseasonal variability of mini‐cold pool off the southern tip of India and its intrusion into the south central Bay of Bengal during summer monsoon season

Cited by 27 publications

References 8 publications

A new atlas of temperature and salinity for the North Indian Ocean

A new atlas of temperature and salinity for the North Indian Ocean

Characteristics of a persistent &quot;pool of inhibited cloudiness&quot; and its genesis over the Bay of Bengal associated with the Asian summer monsoon

Interannual variability of upwelling indices in the Southeastern Arabian Sea: A satellite based study

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Characteristics of a persistent "pool of inhibited cloudiness" and its genesis over the Bay of Bengal associated with the Asian summer monsoon