Interaction of a Low-Pressure System, an Offshore Trough, and Mid-Tropospheric Dry Air Intrusion: The Kerala Flood of August 2018

Kumar, Vinay; Pradhan, P. K.; Sinha, Tushar; Rao, S. Vijaya Bhaskara; Chang, Hao-Po

doi:10.3390/atmos11070740

Cited by 25 publications

(12 citation statements)

References 42 publications

(34 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There was a gradual decrease in rainfall over Kerala from the 16 th onwards with the shift of the band. Interaction between low-pressure systems, offshore troughs, or secondary cyclonic vortices and intrusion of cold dry air to the mid-troposphere can help develop static instability and consequently extreme rainfalls (Nikumbh et al 2020;Kumar et al 2020). The present analysis shows, the intrusion of cold dry air is mainly from the northern side, beyond the Himalayas (Fig.…”

Section: Meridional Mean Of Vertical Velocitymentioning

confidence: 99%

“…Their high-resolution modelling suggests high convective instability due to strong LLJ along with the offshore trough, transport of mid-tropospheric moisture under conducive vertical shear of horizontal wind and transport of moisture from the Bay of Bengal as the major factors behind extreme rainfall. According to Kumar et al (2020), a propagating Low Pressure System (LPS) in the Bay of Bengal caused plenty of rainfall over the west coast of India, central India and the Bay of Bengal. The upper tropospheric anticyclone over the Middle East region inhibited the northward advancement of this LPS.…”

Section: Potential Evaporation and Precipitable Watermentioning

confidence: 99%

“…On the other hand, on the west coast of India, a non-propagating offshore trough was observed. The synergic interaction between LPS, an intrusion of dry air into the mid-troposphere and the offshore trough are the main reasons for the extreme rainfall (Kumar et al 2020). The performance of Numerical Weather Prediction (NWP) models used at the National Centre for Medium Range Weather Forecasting (NCMRWF) in the prediction of the extreme rainfall of Kerala during August 2018 was evaluated by Ashrit et al (2020).…”

Section: Potential Evaporation and Precipitable Watermentioning

confidence: 99%

“…According to Viswanadhapalli et al ( 2019), high convective instability, offshore vortex, moisture transport from mid-troposphere due to horizontal wind shear and mid-tropospheric moisture transport from the Bay of Bengal played major roles in the extreme precipitation event. Kumar et al (2020) showed that the synergic interaction of a lowpressure system in the northern Bay of Bengal, an offshore trough in the south-eastern Arabian Sea and mid-tropospheric dry air intrusion from the Middle East due to an anticyclone caused the extreme rainfall events. This study, investigates the different weather parameters that in uenced the peculiar weather conditions over Kerala during the 2018 monsoon season.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Anomalous Weather Parameters that Lead to the Extreme Rainfall of Kerala in August 2018

Sreedharan¹,

Mathew²,

Sureshkumar³

2021

Preprint

View full text Add to dashboard Cite

Extremely heavy rainfall has been occurred over Kerala, southwest coast of India, during mid-August 2018. The meteorological conditions during this period are analysed, and it is found that a combination of many rain favouring conditions prevailed at that time. The positive phase of Madden Julian Oscillation coupled with a monsoon depression in the Bay of Bengal and a weak trough in the south-eastern Arabian Sea strengthened the Monsoon Low Level Jet bringing moisture-laden winds over Kerala. The rising limb of Walker and Hadley circulations was also found over Kerala, which gave favourable updraft for cloud formation. In addition, the core of the Tropical Easterly Jet was found over the Kerala and Karnataka region. The cyclonic circulation in the mid-troposphere observed around the monsoon depression extended up to the west coast of India. Simultaneous occurrences of all these could have contributed to the extreme rainfall events and severe floods over Kerala.

show abstract

Section: Meridional Mean Of Vertical Velocitymentioning

confidence: 99%

Section: Potential Evaporation and Precipitable Watermentioning

confidence: 99%

Section: Potential Evaporation and Precipitable Watermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Anomalous Weather Parameters that Lead to the Extreme Rainfall of Kerala in August 2018

Sreedharan¹,

Mathew²,

Sureshkumar³

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The direct and indirect effect of the changing climate and its consequences on the global domain, continental scale, and regional scale is still a subject of open discussion. The profound signal of climate change and variability is clearly evidenced by an increase in the number of extreme precipitation events, flash floods, droughts, and heatwaves in recent decades [3][4][5]. Of particular concern, the increase in extreme precipitation events is reasonably associated with an increase in mean global temperature.…”

Section: Introductionmentioning

confidence: 99%

The Connection between Extreme Precipitation Variability over Monsoon Asia and Large-Scale Circulation Patterns

2021

Self Cite

View full text Add to dashboard Cite

Spatial and temporal variability in precipitation has been dramatically changed due to climate variability and climate change over the global domain. Increasing in extreme precipitation events are pronounced in various regions, including monsoon Asia (MA) in recent decades. The present study evaluated precipitation variability in light of intensity, duration, and frequency with several extreme precipitation climate change indices developed by the Expert Team on Climate Change Detection Indices (ETCCDI) over the MA region. This study uses an improved version (APHRO_V1901) of the Asian Precipitation Highly Resolved Observation Data Integration Towards Evaluation of extreme events (APHRODITE-2) gridded rainfall product. Results showed that the spatial variability of the extreme precipitation climate change indices is reflected in the annual mean rainfall distribution in MA. Maximum one-day precipitation (R × 1) and precipitation contributed from extremes (R95) depict a peak in decadal mean rainfall values over topography regions. A significant positive trend in R × 1 (with a slope of 0.3 mm/yr) and precipitation greater than the 95th percentile (R95: with a slope of 0.5 mm/yr) are predominantly observed in decadal trends in regional average extreme precipitation climate change indices over MA. Maritime continental countries exhibit an inclined trend in R10, whereas central Asian arid regions show a decreasing tendency in continuous dry days (CDD). The positive trend in R95 is observed over central India, the monsoon region in China, countries that reside over the equator and some parts of Japan, and the Philippines. When comparing the influence of surface temperature (T) and total column water vapor (TCW) on precipitation climate change indices, TCW seems to be a crucial attributor to climate change indices meridional variability. The mutual correlation analysis depicts that precipitation contributed from extremes (R95) strongly correlates in terms of temporal variability with all extreme precipitation indices. Among various global circulation patterns, the prevalent conditions of sea surface temperature (SST) over the equatorial Pacific Ocean have a significant influence on decadal variability in extreme precipitation climate change indices. R10 and R95 possess a relatively significant correlation (0.86 and 0.91) with the Southern Oscillation Index. The maximum number of consecutive dry days (CDD) shows an increasing trend with a positive phase of the North Atlantic Oscillation Index.

show abstract

Climate, trends and variability of extreme winds along the southwest coast of India

Abdulla,

Aboobacker,

Vethamony

2023

Intl Journal of Climatology

View full text Add to dashboard Cite

The extreme wind climate and its trends and variability of the southwest coast of India, particularly the Kerala coast, are investigated using hourly reanalysis wind speeds for the period 1979–2021. The observed maximum wind speed and 99th percentile wind speed off Kerala coast are 21.0 and 11.3 m·s−1, respectively. The predominant direction of high wind speeds is in the SW–WNW sector, which accounts for 93.5% of the total high winds. Extreme wind speeds in this region are not due to tropical cyclones alone, but also due to seasonal high winds. Seasonally, the premonsoon and SW monsoon extreme winds are predominantly in the WSW–WNW directional sector, while postmonsoon strong winds are present in all directional sectors, but predominantly in the SSW–WNW sector, followed by the E–SSE sector. The 99th percentile wind speeds during premonsoon, SW monsoon and postmonsoon are 8.8, 12.3 and 8.9 m·s−1, respectively. A significant decreasing trend is observed in the 99th percentile wind speeds during 1979–2021, ranging from 3 to 6 cm·s−1·year−1 off Kerala coast. This is in contrast with global increasing extreme wind speeds, and it can be attributed to regional variability as well as weakening of the land–sea thermal gradients associated with rising surface temperature in the Arabian Sea in the light of global warming. In addition to the long‐term declining trend and monthly as well as seasonal features, distinct interannual variations are also noticed in the 99th percentile wind speeds. Analysis shows that the atmospheric teleconnections associated with El Niño–La Niña events and Indian Ocean Dipole have an important role in the variability of extreme wind speeds. The co‐occurrence of positive (negative) IOD with El Niño (La Niña) results in a sharp decline (increase) in extreme wind speeds. Significant decadal variations are also noticed in the 99th percentile wind speeds.

show abstract

Interaction of a Low-Pressure System, an Offshore Trough, and Mid-Tropospheric Dry Air Intrusion: The Kerala Flood of August 2018

Cited by 25 publications

References 42 publications

The Anomalous Weather Parameters that Lead to the Extreme Rainfall of Kerala in August 2018

The Anomalous Weather Parameters that Lead to the Extreme Rainfall of Kerala in August 2018

The Connection between Extreme Precipitation Variability over Monsoon Asia and Large-Scale Circulation Patterns

Climate, trends and variability of extreme winds along the southwest coast of India

Contact Info

Product

Resources

About