Variability of Mixed-Layer Heights over the Indian Ocean and Central Arabian Sea during INDOEX, IFP-99

Abstract. Spatial and temporal variability of the Marine Atmospheric Boundary Layer (MABL) height for the Indian Ocean Experiment (INDOEX) study period are examined using the data collected through Cross-chained LORAN (Long-Range Aid to Navigation) Atmospheric Sounding System (CLASS) launchings during the Northern Hemispheric winter monsoon period. This paper reports the results of the analyses of the data collected during the pre-INDOEX (1997) and the INDOEX-First Field Phase (FFP; 1998) in the latitude range 14°N to 20°S over the Arabian Sea and the Indian Ocean. Mixed layer heights are derived from thermodynamic profiles and they indicated the variability of heights ranging from 400m to 1100m during daytime depending upon the location. Mixed layer heights over the Indian Ocean are slightly higher during the INDOEX-FFP than the pre-INDOEX due to anomalous conditions prevailing during the INDOEX-FFP. The trade wind inversion height varied from 2.3km to 4.5km during the pre-INDOEX and from 0.4km to 2.5km during the INDOEX-FFP. Elevated plumes of polluted air (lofted aerosol plumes) above the marine boundary layer are observed from thermodynamic profiles of the lower troposphere during the INDOEX-FFP. These elevated plumes are examined using 5-day back trajectory analysis and show that one group of air mass travelled a long way from Saudi Arabia and Iran/Iraq through India before reaching the location of measurement, while the other air mass originates from India and the Bay of Bengal.

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Vallicula multiformis Rankin, 1956 (Ctenophora, Platyctenida): first record from the Indian Ocean

Check List ◽

10.15560/11.1.1544 ◽

2015 ◽

Vol 11 (1) ◽

pp. 1544 ◽

Cited By ~ 3

Author(s):

Amruta Prasade ◽

Deepak Apte ◽

Purushottam Kale ◽

Otto M.P. Oliveira

Keyword(s):

Indian Ocean ◽

Geographic Distribution ◽

West Coast ◽

Arabian Sea ◽

First Record ◽

West Coast Of India ◽

The Pacific ◽

The Indian Ocean ◽

First Time

The benthic ctenophore Vallicula multiformis Rankin, 1956 is recorded for the first time in the Arabian Sea, from the Gulf of Kutch, west coast of India in March 2013. This occurrence represents a remarkable extension of its geographic distribution that until now included only known the Pacific and Atlantic oceans.

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Microstructure of Climate-Forcing Aerosols: Aircraft Traverses from Clean to Polluted Conditions in the Indian Ocean

Microscopy and Microanalysis ◽

10.1017/s1431927600028476 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 480-481

Author(s):

James R. Anderson ◽

Peter Crozier

Keyword(s):

Indian Ocean ◽

Solar Radiation ◽

Arabian Sea ◽

Aerosol Particles ◽

Climate Forcing ◽

Convergence Zone ◽

Sulfate Aerosols ◽

Large Area ◽

Inter Tropical Convergence Zone ◽

The Indian Ocean

The Indian Ocean Experiment (INDOEX) was conducted in Feb.-Mar. 1999 in a large area of the Indian Ocean, Bay of Bengal, and Arabian Sea to investigate climate forcing produced by pollutant aerosol particles being transported out of India, Pakistan, and Indochina during the Northeast (“Dry“) Monsoon2. Pollutant aerosols can be transported a thousand km or more by prevailing winds as far south as the Inter-tropical Convergence Zone (ITCZ), the convective band that separates Northern and Southern Hemisphere tropospheric air. We present here results from TEM examination of aerosol particles collected on INDOEX research flights of the NCAR C-130 aircraft.The climate forcing properties of sulfate aerosols over the oceans have long been recognized2. Sulfate and other particles scatter incoming solar radiation, reducing the amount of light (and heat) incident on the ocean surface and thus causing a cooling effect which may locally counter some of the warming effect due to greenhouse gases.

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A discussion concerning the floor of the northwest Indian Ocean - Physciography of the Indian Ocean

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1966.0003 ◽

1966 ◽

Vol 259 (1099) ◽

pp. 137-149 ◽

Cited By ~ 32

Keyword(s):

Indian Ocean ◽

Arabian Sea ◽

Polar Front ◽

Mountain Range ◽

Gangetic Plain ◽

Southwest Indian Ocean ◽

Oceanic Ridge ◽

The Indian Ocean ◽

Lateral Displacements ◽

Ocean Ridge

As a result of the International Indian Ocean Expedition, the bottom of the Indian Ocean is now one of the best known areas of the ocean floor. The Mid-Indian Ocean Ridge, a rugged mountain range, lies in the centre of the Indian Ocean. North-northeast trending fractures offset the axis of the ridge. In the Arabian Sea these fractures are right lateral; in the southwest Indian Ocean they are left lateral. Displacements range from a few miles* to over 200 miles. The northeast Arabian Sea and the Bay of Bengal are occupied by huge abyssal cones built by sediments discharged from the Indo-Gangetic plain. Extensive abyssal plains lie seaward of the abyssal cones. In low latitudes smooth topography is characteristic of the continental rise, the abyssal cones, and the oceanic rises. However, near the polar front smooth c swale9 topography laps over the normally rugged Mid-Oceanic Ridge. This c swale5 smoothing appears the result of the higher organic productivity of the Antarctic seas. Microcontinents, mostly linear meridional ridges, are unique features of the Indian Ocean. These massive but smooth-surfaced blocks contrast markedly with the broad rugged Mid-Oceanic Ridge.

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An Arabian Sea Chart of the Middle Ages

Journal of Navigation ◽

10.1017/s037346330004220x ◽

1975 ◽

Vol 28 (4) ◽

pp. 434-448

Author(s):

H. Grosset-Grange

Keyword(s):

Indian Ocean ◽

Fifteenth Century ◽

Middle Ages ◽

Arabian Sea ◽

Place Names ◽

The Indian Ocean ◽

The Middle Ages

This study of fifteenth-century Arab sailing directions for the Indian Ocean is translated from a paper which was published in the July 1974 issue of Navigation, the Journal of the French Institute of Navigation. The spelling of modern place names has been assimilated to that of the Admiralty Charts and Sailing Directions but other Arabic names and terms have been left in the authors' approximate transliteration. Quotations from the Arabic texts are printed in italics.

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First occurrence of the moray eel Gymnothorax prolatus Sasaki & Amaoka, 1991 (Teleostei: Anguilliformes: Muraenidae) from the northern Indian Ocean

Marine Biodiversity Records ◽

10.1017/s1755267215000834 ◽

2015 ◽

Vol 8 ◽

Cited By ~ 1

Author(s):

Anil Mohapatra ◽

Dipanjan Ray ◽

David G. Smith

Keyword(s):

Indian Ocean ◽

Arabian Sea ◽

Western Indian Ocean ◽

Northern Indian Ocean ◽

The North ◽

First Occurrence ◽

The Indian Ocean ◽

First Time ◽

North Western ◽

Moray Eel

Gymnothorax prolatusis recorded for the first time from the Indian Ocean on the basis of four specimens collected in the Bay of Bengal off India and one from the Arabian Sea off Pakistan. These records extend the range of the species from Taiwan to the north-western Indian Ocean.

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Asymmetry of the Indian Ocean Dipole. Part I: Observational Analysis

Journal of Climate ◽

10.1175/2008jcli2222.1 ◽

2008 ◽

Vol 21 (18) ◽

pp. 4834-4848 ◽

Cited By ~ 72

Author(s):

Chi-Cherng Hong ◽

Tim Li ◽

LinHo ◽

Jong-Seong Kug

Keyword(s):

Indian Ocean ◽

Mixed Layer ◽

Indian Ocean Dipole ◽

Heat Budget ◽

Mature Phase ◽

Budget Analysis ◽

Nonlinear Advection ◽

Negative Skewness ◽

The Indian Ocean ◽

The Asymmetry

The physical mechanism for the amplitude asymmetry of SST anomalies (SSTA) between the positive and negative phases of the Indian Ocean dipole (IOD) is investigated, using Simple Ocean Data Assimilation (SODA) and NCAR–NCEP data. It is found that a strong negative skewness appears in the IOD east pole (IODE) in the mature phase [September–November (SON)], while the skewness in the IOD west pole is insignificant. Thus, the IOD asymmetry is primarily caused by the negative skewness in IODE. A mixed-layer heat budget analysis indicates that the following two air–sea feedback processes are responsible for the negative skewness. The first is attributed to the asymmetry of the wind stress–ocean advection–SST feedback. During the IOD developing stage [June–September (JJAS)], the ocean linear advection tends to enhance the mixed-layer temperature tendency, while nonlinear advection tends to cool the ocean in both the positive and negative events, thus contributing to the negative skewness in IODE. The second process is attributed to the asymmetry of the SST–cloud–radiation (SCR) feedback. For a positive IODE, the negative SCR feedback continues with the increase of warm SSTA. For a negative IODE, the same negative SCR feedback works when the amplitude of SSTA is small. After reaching a critical value, the cold SSTA may completely suppress the mean convection and lead to cloud free conditions; a further drop of the cold SSTA does not lead to additional thermal damping so that the cold SSTA may grow faster. A wind–evaporation–SST feedback may further amplify the asymmetry induced by the aforementioned nonlinear advection and SCR feedback processes.

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Drivers of oceanic exchange through the Indonesian Throughflow since the late 1800s – a synthesis of coral δ18O and high-resolution ocean models

10.5194/egusphere-egu2020-11181 ◽

2020 ◽

Author(s):

Sujata Murty ◽

Caroline Ummenhofer ◽

Markus Scheinert ◽

Erik Behrens ◽

Arne Biastoch ◽

...

Keyword(s):

Indian Ocean ◽

Mixed Layer ◽

Mixed Layer Depth ◽

Heat Content ◽

Phase Changes ◽

Boreal Winter ◽

Indonesian Throughflow ◽

Layer Depth ◽

Ocean Variability ◽

The Indian Ocean

The Indonesian Throughflow (ITF) serves as an important oceanic teleconnection for Indo-Pacific climate, altering heat and buoyancy transport from the Pacific to the Indian Ocean. Equatorial Pacific wind forcing transmitted through the ITF impacts interannual to interdecadal Indian Ocean thermocline depth and heat content, with implications for preconditioning Indian Ocean Dipole events. Yet the modulation of Indian Ocean thermal properties at seasonal timescales is still poorly understood. Here we synthesize coral &#948;18O records, instrumental indices (El Ni&#241;o Southern Oscillation (ENSO), Asian Monsoon), and simulated ocean variability (sea surface salinity (SSS) and temperature (SST), heat content, mixed layer depth) from state-of-the-art NEMO ocean model hindcasts to explore drivers of seasonal to multi-decadal variability. All coral sites are located within main ITF pathways and are influenced by monsoon-driven, buoyant South China Sea (SCS) surface waters during boreal winter that obstruct surface ITF flow and reduce heat transport to the Indian Ocean. Makassar and Lombok Strait coral &#948;18O co-varies with simulated SSS, subsurface heat content anomalies (50-350m) and mixed layer depth at the coral sites and in the eastern Indian Ocean. At decadal timescales, simulated boreal winter ocean variability at the coral sites additionally indicates a potential intensification of the SCS buoyancy plug from the mid- to late-20th century. Notably, the variability in these coral and model responses reveals sensitivity to phase changes in the Interdecadal Pacific Oscillation and the East Asian Winter Monsoon. These results collectively suggest that the paleoproxy records are capturing important features of regional hydrography and Indo-Pacific exchange, including responses to regional monsoon variability. Such proxy-model comparison is critical for understanding the drivers of variability related to changes in ITF oceanic teleconnections over the 19th and 20th centuries.

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Remote influences on the Indian monsoon Low-Level Jet intraseasonal variations

10.5194/egusphere-egu2020-19411 ◽

2020 ◽

Author(s):

Takeshi Izumo ◽

Maratt Satheesan Swathi ◽

Matthieu Lengaigne ◽

Jérôme Vialard ◽

Dr Ramesh Kumar

Keyword(s):

Indian Ocean ◽

Indian Summer Monsoon ◽

Arabian Sea ◽

Large Scale ◽

Indian Monsoon ◽

Westerly Wind ◽

Low Level ◽

Intraseasonal Variations ◽

The Indian Ocean ◽

Low Level Jet

A strong Low-Level Jet (LLJ), also known as the Findlater jet, develops over the Arabian Sea during the Indian summer monsoon. This jet is an essential source of moisture for monsoonal rainfall over the densely-populated Indian subcontinent and is a key contributor to the Indian Ocean oceanic productivity by sustaining the western Arabian Sea upwelling systems. The LLJ intensity fluctuates intraseasonally within the ~20- to 90-day band, in relation with the northward-propagating active and break phases of the Indian summer monsoon. Our observational analyses reveal that these large-scale regional convective perturbations&#160; only explain about half of the intraseasonal LLJ variance, the other half being unrelated to large-scale convective perturbations over the Indian Ocean. We show that convective fluctuations in two regions outside the Indian Ocean can remotely force a LLJ intensification, four days later. Enhanced atmosphericdeep convection over the northwestern tropical Pacific yields westerly wind anomalies that propagate westward to the Arabian Sea as baroclinic atmospheric Rossby Waves. Suppressed convection over the eastern Pacific / North American monsoon region yields westerly wind anomalies that propagate eastward to the Indian Ocean as dry baroclinic equatorial Kelvin waves. Those largely independent remote influences jointly explain ~40% of the intraseasonal LLJ variance that is not related to convective perturbations over the Indian Ocean (i.e. ~20% of the total), with the northwestern Pacific contributing twice as much as the eastern Pacific. Taking into account these two remote influences should thus enhance the ability to predict the LLJ.&#160;Related reference:&#160;Swathi M.S, Takeshi Izumo, Matthieu Lengaigne, J&#233;r&#244;me Vialard and M.R. Ramesh Kumar:Remote influences on the Indian monsoon Low-Level Jet intraseasonal variations, accepted in Climate Dynamics.

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Mancham, Sir James Richard Marie, (11 Aug. 1939–8 Jan. 2017), international statesman for peace; international trade consultant, since 1981; Founding President, Republic of the Seychelles, 1976–77; Chairman: Mahé Publications Ltd, since 1984; International Promotion Marketing and Development Ltd; Publisher, Voice of the Indian Ocean and the Arabian Sea

10.1093/ww/9780199540884.013.26467 ◽

2007 ◽

Keyword(s):

International Trade ◽

Indian Ocean ◽

Arabian Sea ◽

The Indian Ocean

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