scholarly journals Mechanism of cold water regions observed in winter in the Indian Ocean

MAUSAM ◽  
2021 ◽  
Vol 48 (4) ◽  
pp. 645-656
Author(s):  
MASAHISA KUBOTA ◽  
MORIHERI KAWAGUCHI
Keyword(s):  
Heat Flux ◽  
Arabian Sea ◽  
Cold Water ◽  
The Other ◽  
Sea Surface ◽  
Shortwave Radiation ◽  
Boreal Winter ◽  
Observation Data ◽  
Net Heat Flux ◽  
The Indian Ocean

Two cold sea surface temperature (SST) regions are found in the Arabian Sea in boreal winter. One is located northeast of Madagascar, and another is located in a northern part of Arabian Sea. The mechanism for appearance of the cold water is investigated by using monthly climatological ocean observation data. The cold water found northeast of Madagascar is caused by upwelling owing to Ekman divergence associated with a reversal of wind direction. On the other hand, the decrease in SST in a northern part of Arabian Sea is basically caused by decrease of net heat flux associated with reduced shortwave radiation and increased latent heat flux. These results are consistent with results obtained from a numerical investigation by McCreary and Kundu (1989).    

scholarly journals Annual, Seasonal, and Interannual Variability of Air–Sea Heat Fluxes in the Indian Ocean

2007 ◽  
Vol 20 (13) ◽  
pp. 3190-3209 ◽  
Author(s):  
Lisan Yu ◽  
Xiangze Jin ◽  
Robert A. Weller
Keyword(s):  
Heat Flux ◽  
Indian Ocean ◽  
Interannual Variability ◽  
Seasonal Cycle ◽  
Arabian Sea ◽  
Heat Fluxes ◽  
The Other ◽  
Net Heat Flux ◽  
The Indian Ocean ◽  
The Mean

Abstract This study investigated the accuracy and physical representation of air–sea surface heat flux estimates for the Indian Ocean on annual, seasonal, and interannual time scales. Six heat flux products were analyzed, including the newly developed latent and sensible heat fluxes from the Objectively Analyzed Air–Sea Heat Fluxes (OAFlux) project and net shortwave and longwave radiation results from the International Satellite Cloud Climatology Project (ISCCP), the heat flux analysis from the Southampton Oceanography Centre (SOC), the National Centers for Environmental Prediction reanalysis 1 (NCEP1) and reanalysis-2 (NCEP2) datasets, and the European Centre for Medium-Range Weather Forecasts operational (ECMWF-OP) and 40-yr Re-Analysis (ERA-40) products. This paper presents the analysis of the six products in depicting the mean, the seasonal cycle, and the interannual variability of the net heat flux into the ocean. Two time series of in situ flux measurements, one taken from a 1-yr Arabian Sea Experiment field program and the other from a 1-month Joint Air–Sea Monsoon Interaction Experiment (JASMINE) field program in the Bay of Bengal were used to evaluate the statistical properties of the flux products over the measurement periods. The consistency between the six products on seasonal and interannual time scales was investigated using a standard deviation analysis and a physically based correlation analysis. The study has three findings. First of all, large differences exist in the mean value of the six heat flux products. Part of the differences may be attributable to the bias in the numerical weather prediction (NWP) models that underestimates the net heat flux into the Indian Ocean. Along the JASMINE ship tracks, the four NWP modeled mean fluxes all have a sign opposite to the observations, with NCEP1 being underestimated by 53 W m−2 (the least biased) and ECMWF-OP by 108 W m−2 (the most biased). At the Arabian Sea buoy site, the NWP mean fluxes also have an underestimation bias, with the smallest bias of 26 W m−2 (ERA-40) and the largest bias of 69 W m−2 (NCEP1). On the other hand, the OAFlux+ISCCP has the best comparison at both measurement sites. Second, the bias effect changes with the time scale. Despite the fact that the mean is biased significantly, there is no major bias in the seasonal cycle of all the products except for ECMWF-OP. The latter does not have a fixed mean due to the frequent updates of the model platform. Finally, among the four products (OAFlux+ISCCP, ERA-40, NCEP1, and NCEP2) that can be used for studying interannual variability, OAFlux+ISCCP and ERA-40 Qnet have good consistency as judged from both statistical and physical measures. NCEP1 shows broad agreement with the two products, with varying details. By comparison, NCEP2 is the least representative of the Qnet variabilities over the basin scale.

Variational assimilation of observation data in the mathematical model of the Baltic Sea dynamics

2015 ◽  
Vol 30 (4) ◽  
Author(s):  
Valeriy I. Agoshkov ◽  
Eugene I. Parmuzin ◽  
Vladimir B. Zalesny ◽  
Victor P. Shutyaev ◽  
Natalia B. Zakharova ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Heat Flux ◽  
Baltic Sea ◽  
Satellite Observation ◽  
Sea Surface ◽  
Observation Data ◽  
The Baltic Sea ◽  
Variational Assimilation ◽  
The Baltic ◽  
The Mathematical Model

AbstractA mathematical model of the dynamics of the Baltic Sea is considered. A problem of variational assimilation of sea surface temperature (SST) data is formulated and studied. Based on variational assimilation of satellite observation data, an algorithm solving the inverse problem of heat flux restoration on the interface of two media is proposed. The results of numerical experiments reconstructing the heat flux functions in the problem of variational assimilation of SST observation data are presented. The influence of SST assimilation on other hydrodynamic parameters of the model is considered.

scholarly journals Atmosphere-Driven Cold SST Biases Over The Western North Pacific in The GloSea5 Seasonal Forecast System

2021 ◽  
Author(s):  
Ajin Cho ◽  
Hajoon Song ◽  
Yong-Jin Tak ◽  
Sang-Wook Yeh ◽  
Soon-Il An ◽  
...  
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Western North Pacific ◽  
Primary Source ◽  
Seasonal Forecast ◽  
Ocean Model ◽  
Sea Surface ◽  
Shortwave Radiation ◽  
Forecast System ◽  
Sst Bias

Abstract The predictability of the sea surface temperature (SST) in seasonal forecast systems is crucial for accurate seasonal predictions. In this study, we evaluate the prediction of SST in the Global Seasonal forecast system version 5 (GloSea5) hindcast with particular interest over the western North Pacific (WNP) in which the SST can modify atmospheric convection and the East Asian weather. GloSea5 has a cold SST bias in the WNP that grows over at least 7 months. The bias originates from the surface heat flux in which the latent heat flux bias shows the biggest contribution. We identify the overestimated cloud in the first few days after initialization that causes insufficient shortwave radiation and negative bias of the surface net heat flux. Uncoupled ocean model experiments infer that the ocean model is unlikely the primary source of the SST bias.

scholarly journals Comparative Analysis of Sea Surface Temperature Pattern in the Eastern and Western Gulfs of Arabian Sea and the Red Sea in Recent Past Using Satellite Data

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Neha Nandkeolyar ◽  
Mini Raman ◽  
G. Sandhya Kiran ◽  
Ajai
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Red Sea ◽  
Arabian Sea ◽  
Sea Surface ◽  
Temperature Pattern ◽  
The Indian Ocean ◽  
Sst Anomaly ◽  
The Persian Gulf ◽  
Very High

With unprecedented rate of development in the countries surrounding the gulfs of the Arabian Sea, there has been a rapid warming of these gulfs. In this regard, using Advanced Very High Resolution Radiometer (AVHRR) data from 1985 to 2009, a climatological study of Sea Surface Temperature (SST) and its inter annual variability in the Persian Gulf (PG), Gulf of Oman (GO), Gulf of Aden (GA), Gulf of Kutch (KTCH), Gulf of Khambhat (KMBT), and Red Sea (RS) was carried out using the normalized SST anomaly index. KTCH, KMBT, and GA pursued the typical Arabian Sea basin bimodal SST pattern, whereas PG, GO, and RS followed unimodal SST curve. In the western gulfs and RS, from 1985 to 1991-1992, cooling was observed followed by rapid warming phase from 1993 onwards, whereas in the eastern gulfs, the phase of sharp rise of SST was observed from 1995 onwards. Strong influence of the El Niño and La Niña and the Indian Ocean Dipole on interannual variability of SST of gulfs was observed. Annual and seasonal increase of SST was lower in the eastern gulfs than the western gulfs. RS showed the highest annual increase of normalized SST anomaly (+0.64/decade) followed by PG (+0.4/decade).

scholarly journals A new amphipod species from the Indian Ocean (Crustacea: Amphipoda: Lysianassoidea: Podoprionidae)

Zootaxa ◽  
2005 ◽  
Vol 861 (1) ◽  
pp. 1
Author(s):  
TAMMY HORTON
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
Arabian Sea ◽  
The Other ◽  
Amphipod Species ◽  
Northern Arabian Sea ◽  
The Indian Ocean ◽  
A New Species

A new species of the genus Podoprion is described. The species can be distinguished from the other species in the genus, Podoprion bolivari Chevreux, 1891, P. ruffoi Lowry & Stoddart, 1996, and P. mediterraneum Kaim-Malka, 2004, by the shape of gnathopod 2 propodus, coxa 4, number and size of serrations on pereopod 5 basis, and characters of the mouthparts. Material was collected by baited trap at 1185 m off the coast of Pakistan in the northern Arabian Sea.

scholarly journals North Pacific subtropical sea surface temperature frontogenesis and its connection with the atmosphere above

2018 ◽  
Author(s):  
Leying Zhang ◽  
Haiming Xu ◽  
Jing Ma ◽  
Ning Shi ◽  
Jiechun Deng
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North Pacific ◽  
Ocean Currents ◽  
Sea Surface ◽  
Aleutian Low ◽  
The North ◽  
Net Heat Flux ◽  
Temperature Advection

Abstract. The frontogenesis of the North Pacific subtropical sea surface temperature front (NPSTF) occurring from October to the following February is examined quantitatively based on the mixed-layer energy budget equation, with a focus on its connection with the atmosphere above. Diagnosis results show that the net heat flux dominates the frontogenesis from October to December, while the meridional temperature advection in the ocean contributes equally as or even more than the net heat flux in January and February. The atmosphere is critical to the frontogenesis of the NPSTF, including the direct effect of the net heat flux and the indirect effect through the Aleutian low. Further analyses demonstrate that the latent heat flux (the shortwave radiation) dominates the net heat flux in October (from November to February). The meridional temperature advection in the ocean is mostly owing to the meridional Ekman convergence, which is related to the Aleutian low. Climatologically, the strengthening and southward migration of the Aleutian low from October to the following February are characterized by the acceleration and southward shift of the westerly wind to the south, respectively, which can drive southward ocean currents. Correspondingly, the southward ocean currents give the colder meridional advection to the north of the NPSTF in January and February, favoring the frontogenesis. In addition, the Aleutian low plays a role in transforming the dominant effect of the net heat flux to the joint effect of the meridional temperature advection and the net heat flux in January. CESM1.0.3 model with a slab ocean model further confirms the important influence of the atmosphere on the frontogenesis and on the meridional temperature advection.

Impacts of Shortwave Penetration Depth on Large-Scale Ocean Circulation and Heat Transport

2005 ◽  
Vol 35 (6) ◽  
pp. 1103-1119 ◽  
Author(s):  
Colm Sweeney ◽  
Anand Gnanadesikan ◽  
Stephen M. Griffies ◽  
Matthew J. Harrison ◽  
Anthony J. Rosati ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Transport ◽  
Penetration Depth ◽  
Ocean Circulation ◽  
Mixed Layer ◽  
Large Scale ◽  
Sea Surface ◽  
Shortwave Radiation ◽  
Sea Surface Temperatures ◽  
Surface Temperatures

Abstract The impact of changes in shortwave radiation penetration depth on the global ocean circulation and heat transport is studied using the GFDL Modular Ocean Model (MOM4) with two independent parameterizations that use ocean color to estimate the penetration depth of shortwave radiation. Ten to eighteen percent increases in the depth of 1% downwelling surface irradiance levels results in an increase in mixed layer depths of 3–20 m in the subtropical and tropical regions with no change at higher latitudes. While 1D models have predicted that sea surface temperatures at the equator would decrease with deeper penetration of solar irradiance, this study shows a warming, resulting in a 10% decrease in the required restoring heat flux needed to maintain climatological sea surface temperatures in the eastern equatorial Atlantic and Pacific Oceans. The decrease in the restoring heat flux is attributed to a slowdown in heat transport (5%) from the Tropics and an increase in the temperature of submixed layer waters being transported into the equatorial regions. Calculations were made using a simple relationship between mixed layer depth and meridional mass transport. When compared with model diagnostics, these calculations suggest that the slowdown in heat transport is primarily due to off-equatorial increases in mixed layer depths. At higher latitudes (5°–40°), higher restoring heat fluxes are needed to maintain sea surface temperatures because of deeper mixed layers and an increase in storage of heat below the mixed layer. This study offers a way to evaluate the changes in irradiance penetration depths in coupled ocean–atmosphere GCMs and the potential effect that large-scale changes in chlorophyll a concentrations will have on ocean circulation.

scholarly journals Impact of the April–May SAM on Central Pacific Ocean sea temperature over the following three seasons

2021 ◽  
Author(s):  
Ting Liu ◽  
Jianping Li ◽  
Cheng Sun ◽  
Tao Lian ◽  
Yazhou Zhang
Keyword(s):  
Indian Ocean ◽  
Cold Water ◽  
Southern Oscillation ◽  
Equatorial Pacific ◽  
Boreal Winter ◽  
Central Pacific ◽  
Sea Temperature ◽  
Easterly Wind ◽  
The Indian Ocean ◽  
The Impact

AbstractAlthough the impact of the extratropical Pacific signal on the El Niño–Southern Oscillation has attracted increasing concern, the impact of Southern Hemisphere Annular Mode (SAM)-related signals from outside the southern Pacific Basin on the equatorial sea temperature has received less attention. This study explores the lead correlation between the April–May (AM) SAM and central tropical Pacific sea temperature variability over the following three seasons. For the positive AM SAM case, the related simultaneous warm SST anomalies in the southeastern Indian Ocean favor significant regulation of vertical circulation in the Indian Ocean with anomalous ascending motion in the tropics. This can further enhance convection over the Marine Continent, which induces a significant horizontal Kelvin response and regulates the vertical Walker circulation. These two processes both result in the anomalous easterlies east of 130° E in the equatorial Pacific during AM. These easterly anomalies favor oceanic upwelling and eastward propagation of the cold water into the central Pacific. The cold water in turn amplifies the development of the easterly wind and further maintains the cold water into the boreal winter. The results presented here not only provide a possible link between extratropical climate variability in the Indian Ocean and climate variation in the equatorial Pacific, but also shed new light on the short-term prediction of tropical central Pacific sea temperature.

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