Convectively-coupled High-frequency waves triggered Kerala floods in 2018 and 2019

Mapping Intimacies ◽

10.21203/rs.3.rs-574169/v1 ◽

2021 ◽

Author(s):

KIRAN S R

Keyword(s):

Indian Ocean ◽

Extreme Precipitation ◽

High Frequency ◽

Systematic Approach ◽

East Coast ◽

East Indian ◽

South Indian ◽

Indian State ◽

High Frequency Waves ◽

East Indian Ocean

Abstract Floods have repeatedly battered the South Indian state, Kerala, as a result of extremely anomalous rainfall during Boreal Summers, since 2018. Previous studies have seldom adopted a systematic approach to understand the phenomenon responsible for the extreme events. Hence, this study intends to identify this dynamical phenomenon based on spectral methods, and attempts to render a preliminary solution to the problem. The study exposes the presence of westward-propagating high-frequency tropical atmospheric waves of 5-8 days period, which originated from east Indian Ocean or West Pacific and headed towards the east coast of Africa. The wave troughs ensured sufficient moisture availability along its path, causing extreme precipitation over Kerala on the way.

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Convectively-coupled High-frequency Atmospheric waves triggered Kerala floods in 2018 and 2019

10.21203/rs.3.rs-954078/v1 ◽

2021 ◽

Author(s):

KIRAN S R

Keyword(s):

Extreme Events ◽

High Frequency ◽

Heavy Rainfall ◽

Systematic Approach ◽

East Coast ◽

The State ◽

Equatorial Waves ◽

South Indian ◽

Indian State ◽

Normal Rainfall

Abstract Floods have repeatedly battered the South Indian state, Kerala, as a result of the unprecedented heavy rainfall during Boreal Summers, in recent years. The state witnessed large departures from normal rainfall in 2018 and 2019. Previous studies have seldom adopted a systematic approach to understand the phenomenon responsible for the recurrent extreme events. Hence, this study, based on spectral methods, identifies a characteristic propagation of high-frequency equatorial waves in the atmosphere, which travelled from near tropical west Pacific to the east coast of Africa. These waves stimulated intense convection and ensured sufficient availability of moisture over the state, and are hence responsible for Kerala Floods.

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Dispersal of the larval stage of southern bluefin tuna, Thunnus maccoyii, in the east Indian Ocean

Coastal and Estuarine Studies - The Bio‐Physics of Marine Larval Dispersal ◽

10.1029/ce045p0137 ◽

1994 ◽

pp. 137-148

Author(s):

T. L. O. Davis ◽

V. D. Lyne

Keyword(s):

Indian Ocean ◽

Larval Stage ◽

Bluefin Tuna ◽

East Indian ◽

Southern Bluefin Tuna ◽

East Indian Ocean

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DMS sea-to-air fluxes and their influence on sulfate aerosols over the Southern Ocean, south-east Indian Ocean and north-west Pacific Ocean

Environmental Chemistry ◽

10.1071/en21003 ◽

2021 ◽

Author(s):

Miming Zhang ◽

Christa A. Marandino ◽

Jinpei Yan ◽

Qi Lin ◽

Keyhong Park ◽

...

Keyword(s):

Pacific Ocean ◽

Indian Ocean ◽

Southern Ocean ◽

Sulfate Aerosols ◽

West Pacific ◽

North West ◽

East Indian ◽

West Pacific Ocean ◽

East Indian Ocean

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Seasonal variations in the Indian Ocean along 110°E. I. Hydrological structure of the upper 500 m

Marine and Freshwater Research ◽

10.1071/mf9690001 ◽

1969 ◽

Vol 20 (1) ◽

pp. 1 ◽

Cited By ~ 62

Author(s):

DJ Rochford

Keyword(s):

Indian Ocean ◽

Surface Waters ◽

Water Masses ◽

Surface Currents ◽

Temperature Changes ◽

East Indian ◽

Hydrological Structure ◽

The Indian Ocean ◽

The Tropics ◽

East Indian Ocean

Tropical and subtropical water masses at surface and subsurface depths were separated by their salinity, temperature, oxygen, and nutrient characteristics. The annual mean depths and latitudinal extent of these water masses were determined. Annual changes in the upper 50 m were generally so small relative to those found in other oceans that advection and mixing must have been less important in their genesis than local climatic changes. There was a barely significant seasonal rhythm in surface phosphate and nitrate, with peak occurrences of each some 6 months apart. At each latitude the permanent thermal discontinuity centred around a particular isotherm varied little in intensity during the year, but rose and fell in accordance with surface currents. The thermocline south of c. 18�S. varied little in depth but greatly in intensity during the summer. The depth of the mixed layer was much less in summer and at all times shallower in the tropics. The depth of this layer was governed more by the accumulation of surface waters by zonal currents and eddies, than by wind stress or convective overturn. Therefore there was little difference from south to north, or month to month, in average nutrient values of this mixed column. The movement of the various surface waters, deduced from salinity and temperature changes during the year, usually agrees with geostrophic currents across 110�E, and ships' observations of surface currents in the south-east Indian Ocean.

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