The Chennai extreme rainfall event in 2015: The Bay of Bengal connection

Boyaj, Alugula; Ashok, Karumuri; Ghosh, Subimal; Devanand, Anjana; Govardhan, Dandu

doi:10.1007/s00382-017-3778-7

Cited by 42 publications

(21 citation statements)

References 27 publications

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“…While this region receives its moisture from the oceans, the importance of the LULC can be conjectured to be relatively higher owing to its location. Another distinction among the states is, because of the seasonality, the co‐occurring El Niño's have a propensity to exacerbate the rainfall in Tamil Nadu, unlike their detrimental effect on rainfall in the rest of India, including Telangana and Kerala (Amat and Ashok, 2018; Boyaj et al ., 2018; Ashok et al ., 2019). Therefore, background factors, which play a major role in defining the synoptic conditions associated with the local rainfall, can be different in these states.…”

Section: Introductionmentioning

confidence: 99%

Increasing heavy rainfall events in south India due to changing land use and land cover

Boyaj

Dasari

Hoteit

et al. 2020

Quart J Royal Meteoro Soc

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Through an analysis of land use and land cover (LULC) data for the years 2005 and 2017 from the Advanced Wide Field Sensor onboard the Indian Remote Sensing satellite, we find considerable changes in the LULC in three major states of south India, namely, Tamil Nadu, Telangana and Kerala. This change is mainly due to increasing urbanization, in addition to the change of prevalent mixed forest into deciduous needle/leaf forest in Kerala. Motivated by this finding, we study the impact of these LULC changes over a decade on the extremes of twelve heavy rainfall events in these states through several sensitivity experiments with a convection‐permitting Weather Research and Forecasting model, by changing the LULC boundary conditions. We particularly focus on three representative heavy rainfall events, specifically, over (a) Chennai (1 December 2015), (b) Telangana (24 September 2016), and (c) Kerala (15 August 2018). The simulated rainfall patterns of the three heavy rainfall events are found to be relatively better with the use of the 2017 LULC boundary conditions. The improvement is statistically significant in the case of the Chennai and Kerala events. On analysis of these simulations, and output from additional simulations we have conducted for nine other heavy rainfall events, we suggest that the recent LULC changes result in higher surface temperatures and sensible heat fluxes, and a deeper and moist boundary layer. This causes a relatively higher convective available potential energy and, consequently, heavier rainfall. We find the LULC changes in the three states, mainly dominated by the increasing urbanization in Telangana and Tamil Nadu, enhance the rainfall during the heavy rainfall events by 20–25%. This is the first extensive investigation of multiple and multi‐regional cases over the Indian region.

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Section: Introductionmentioning

confidence: 99%

Increasing heavy rainfall events in south India due to changing land use and land cover

Boyaj

Dasari

Hoteit

et al. 2020

Quart J Royal Meteoro Soc

Self Cite

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“…In the Indian context, the occurrences of high‐impact weather events and the ERE are escalated not only during the Indian Summer Monsoon (ISM) but also in other seasons (Roxy et al ., ; Boyaj et al ., ; Goswami et al ., ). Significant efforts have been made to understand how the primary climate mode such as the El Niño‐Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) influences the ERE (Gadgil et al ., ; Ajayamohan and Rao, ; Krishnaswamy et al ., ).…”

Section: Introductionmentioning

confidence: 98%

On the linkage between extreme rainfall and the Madden–Julian Oscillation over the Indian region

Anandh

Vissa

2020

Meteorological Applications

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The relationship between extreme rainfall events (ERE) and the Madden-Julian Oscillation (MJO) over the Indian Subcontinent is intriguing. In this regard, the study investigates in detail the association between the ERE and the MJO. Daily Tropical Rainfall Measuring Mission (TRMM) data were used for the period 1998-2015. The real-time multivariate MJO index was applied to classify active and suppressed phases of the MJO. The percentile-based threshold indices, change in probability, logistic regression models and composite analysis were used to understand the statistical and atmospheric circulation features. The results suggest that the frequency and rainfall contribution of the ERE were found to be higher during the active phases of the MJO across the seasons over the geographically distinct regions. The profound influence of the MJO on the ERE was found during the post-monsoon over the southern Indian peninsula and Bay of Bengal regions. During the Indian Summer Monsoon (ISM), the prominent signals of the MJO are limited to the south of 20 N. The logistic regression and cumulative probability changes affirm the above results. The composite analysis of various diagnostic parameters reveals the background synoptic conditions during the post-monsoon and the propagation of the Rossby convective lobe during the ISM might facilitate the occurrences of the ERE during the active phases of the MJO. The study highlights the space-time evolution of the ERE and the relative influence of the MJO across the seasons.Besides, its insights have practical implications for the understanding and prediction of sub-seasonal rainfall extremes over the Indian Subcontinent.

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“…This was attributed to the counteracting effect of aerosols and greenhouse gases. Some of the recent case studies about Chennai floods of December 2015 investigated the impact of climate change based on extreme rainfall data and the relationship with the global phenomenon like El-Nino and La-Nina, but the observations are contrary because of different data sets and methodologies for analysis (Krishnamurthy et al 2018;Boyaj et al 2018).…”

Section: Climate Change Impacts and Flood Risksmentioning

confidence: 99%

Flood risk and adaptation in Indian coastal cities: recent scenarios

et al. 2018

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Coastal cities contrive to spread their transformative influence both into the hinterland, along the coastline, and into the coastal waters themselves. These effects will be intensified in urban agglomerations as the concentration of population and allied activities are more pronounced there compared to the inland regions. Indian coastal cities are no exception, and it is high time to delineate these hazard-prone regions and implement proper mitigation and adaptation strategies at city scale. This review article provides an assessment regarding quantification, management and climate change impacts of flood risks in Surat, Mumbai, Chennai and Kolkata, which are the most populated coastal cities in India. The flood impacts considered in the existing or prevailing analyses are associated with adverse effects on population, land use of cities, transportation and economy caused by different types of riverine and urban flooding, though coastal flooding, tsunami and storm surge effects are less studied. Mumbai and Kolkata are relatively progressive in the assessment of flood risks and adaptation. The present article also suggests strategies to evaluate the relative progress in the assessment of past and future risks and adaptation. We also discuss the mitigation and adaptation strategies considering the historical importance of these cities. We propose that the strategies should be implemented considering public opinion and should be initialized at the grass root level. Though it is technically difficult to re-plan the city structures in the current scenario, it is possible to adapt to and mitigate the effects of natural hazards through suitable planning and management with the integrated cooperation and involvement of citizens and government as well.

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The Chennai extreme rainfall event in 2015: The Bay of Bengal connection

Cited by 42 publications

References 27 publications

Increasing heavy rainfall events in south India due to changing land use and land cover

Increasing heavy rainfall events in south India due to changing land use and land cover

On the linkage between extreme rainfall and the Madden–Julian Oscillation over the Indian region

Flood risk and adaptation in Indian coastal cities: recent scenarios

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