scholarly journals The Kerala flood of 2018: combined impact of extreme rainfall and reservoir storage

2018 ◽  
Author(s):  
Vimal Mishra ◽  
Saran Aaadhar ◽  
Harsh Shah ◽  
Rahul Kumar ◽  
Dushmanta Ranjan Pattanaik ◽  
...  
Keyword(s):  
Return Period ◽  
Large Scale ◽  
Monsoon Season ◽  
Extreme Rainfall ◽  
Reservoir Storage ◽  
Extreme Precipitation Events ◽  
Full Capacity ◽  
Significant Release ◽  
Combined Impact

Abstract. Extreme precipitation events and flooding that cause losses to human lives and infrastructure have increased under the warming climate. In August 2018, the state of Kerala (India) witnessed large-scale flooding, which affected millions of people and caused 400 or more deaths. Here, we examine the return period of extreme rainfall and the potential role of reservoirs in the recent flooding in Kerala. We show that Kerala experienced 53 % above normal rainfall during the monsoon season (till August 21st) of 2018. Moreover, 1, 2, and 3-day extreme rainfall in Kerala during August 2018 had return periods of 75, 200, and 100 years. Six out of seven major reservoirs were at more than 90 % of their full capacity on August 8, 2018, before extreme rainfall in Kerala. Extreme rainfall at 1–15 days durations in August 2018 in the catchments upstream of the three major reservoirs (Idukki, Kakki, and Periyar) had the return period of more than 500 years. Extreme rainfall and almost full reservoirs resulted in a significant release of water in a short-span of time. Therefore, above normal seasonal rainfall (before August 8, 2018), high reservoir storage, and unprecedented extreme rainfall in the catchments where reservoirs are located worsened the flooding in Kerala. Reservoir operations need be improved using a skillful forecast of extreme rainfall at the longer lead time (4–7 days).

scholarly journals The role of serial European windstorm clustering for extreme seasonal losses as determined from multi-centennial simulations of high-resolution global climate model data

2018 ◽  
Vol 18 (11) ◽  
pp. 2991-3006 ◽  
Author(s):  
Matthew D. K. Priestley ◽  
Helen F. Dacre ◽  
Len C. Shaffrey ◽  
Kevin I. Hodges ◽  
Joaquim G. Pinto
Keyword(s):  
High Resolution ◽  
Return Period ◽  
Large Scale ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Geographic Region ◽  
Near Surface ◽  
Short Period

Abstract. Extratropical cyclones are the most damaging natural hazard to affect western Europe. Serial clustering occurs when many intense cyclones affect one specific geographic region in a short period of time which can potentially lead to very large seasonal losses. Previous studies have shown that intense cyclones may be more likely to cluster than less intense cyclones. We revisit this topic using a high-resolution climate model with the aim to determine how important clustering is for windstorm-related losses. The role of windstorm clustering is investigated using a quantifiable metric (storm severity index, SSI) that is based on near-surface meteorological variables (10 m wind speed) and is a good proxy for losses. The SSI is used to convert a wind footprint into losses for individual windstorms or seasons. 918 years of a present-day ensemble of coupled climate model simulations from the High-Resolution Global Environment Model (HiGEM) are compared to ERA-Interim reanalysis. HiGEM is able to successfully reproduce the wintertime North Atlantic/European circulation, and represent the large-scale circulation associated with the serial clustering of European windstorms. We use two measures to identify any changes in the contribution of clustering to the seasonal windstorm loss as a function of return period. Above a return period of 3 years, the accumulated seasonal loss from HiGEM is up to 20 % larger than the accumulated seasonal loss from a set of random resamples of the HiGEM data. Seasonal losses are increased by 10 %–20 % relative to randomized seasonal losses at a return period of 200 years. The contribution of the single largest event in a season to the accumulated seasonal loss does not change with return period, generally ranging between 25 % and 50 %. Given the realistic dynamical representation of cyclone clustering in HiGEM, and comparable statistics to ERA-Interim, we conclude that our estimation of clustering and its dependence on the return period will be useful for informing the development of risk models for European windstorms, particularly for longer return periods.

scholarly journals The SCOUT-O3 Darwin Aircraft Campaign: rationale and meteorology

2009 ◽  
Vol 9 (1) ◽  
pp. 93-117 ◽  
Author(s):  
D. Brunner ◽  
P. Siegmund ◽  
P. T. May ◽  
L. Chappel ◽  
C. Schiller ◽  
...  
Keyword(s):  
Large Scale ◽  
Monsoon Season ◽  
Deep Convection ◽  
Cirrus Clouds ◽  
Cold Trap ◽  
Kelvin Wave ◽  
Rossby Wave Breaking ◽  
Tropical Tropopause

Abstract. An aircraft measurement campaign involving the Russian high-altitude aircraft M55 Geophysica and the German DLR Falcon was conducted in Darwin, Australia in November and December 2005 as part of the European integrated project SCOUT-O3. The overall objectives of the campaign were to study the transport of trace gases through the tropical tropopause layer (TTL), mechanisms of dehydration close to the tropopause, and the role of deep convection in these processes. In this paper a detailed roadmap of the campaign is presented, including rationales for each flight, and an analysis of the local and large-scale meteorological context in which they were embedded. The campaign took place during the pre-monsoon season which is characterized by a pronounced diurnal evolution of deep convection including a mesoscale system over the Tiwi Islands north of Darwin known as "Hector". This allowed studying in detail the role of deep convection in structuring the tropical tropopause region, in situ sampling convective overshoots above storm anvils, and probing the structure of anvils and cirrus clouds by Lidar and a suite of in situ instruments onboard the two aircraft. The large-scale flow during the first half of the campaign was such that local flights, away from convection, sampled air masses downstream of the "cold trap" region over Indonesia. Abundant cirrus clouds enabled the study of active dehydration, in particular during two TTL survey flights. The campaign period also encompassed a Rossby wave breaking event transporting stratospheric air to the tropical middle troposphere and an equatorial Kelvin wave modulating tropopause temperatures and hence the conditions for dehydration.

scholarly journals Causes and Probability of Occurrence of Extreme Precipitation Events like Chennai 2015

2018 ◽  
Vol 31 (10) ◽  
pp. 3831-3848 ◽  
Author(s):  
Lakshmi Krishnamurthy ◽  
Gabriel A. Vecchi ◽  
Xiaosong Yang ◽  
Karin van der Wiel ◽  
V. Balaji ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Extreme Precipitation ◽  
Radiative Forcing ◽  
Large Scale ◽  
Human Life ◽  
Extreme Floods ◽  
Extreme Precipitation Events ◽  
The Future ◽  
Sst Forcing

Abstract Unprecedented high-intensity flooding induced by extreme precipitation was reported over Chennai in India during November–December of 2015, which led to extensive damage to human life and property. It is of utmost importance to determine the odds of occurrence of such extreme floods in the future, and the related climate phenomena, for planning and mitigation purposes. Here, a suite of simulations from GFDL high-resolution coupled climate models are used to investigate the odds of occurrence of extreme floods induced by extreme precipitation over Chennai and the role of radiative forcing and/or large-scale SST forcing in enhancing the probability of such events in the future. The climate of twentieth-century experiments with large ensembles suggest that the radiative forcing may not enhance the probability of extreme floods over Chennai. Doubling of CO2 experiments also fails to show evidence for an increase of such events in a global warming scenario. Further, this study explores the role of SST forcing from the Indian and Pacific Oceans on the odds of occurrence of Chennai-like floods. Neither El Niño nor La Niña enhances the probability of extreme floods over Chennai. However, a warm Bay of Bengal tends to increase the odds of occurrence of extreme Chennai-like floods. In order to trigger a Chennai like-flood, a conducive weather event, such as a tropical depression over the Bay of Bengal with strong transport of moisture from a moist atmosphere over the warm Bay, is necessary for the intense precipitation.

scholarly journals The role of European windstorm clustering for extreme seasonal losses as determined from a high resolution climate model

2018 ◽  
Author(s):  
Matthew D. K. Priestley ◽  
Helen F. Dacre ◽  
Len C. Shaffrey ◽  
Kevin I. Hodges ◽  
Joaquim G. Pinto
Keyword(s):  
High Resolution ◽  
Return Period ◽  
Large Scale ◽  
Western Europe ◽  
Climate Model ◽  
Severity Index ◽  
Return Periods ◽  
Near Surface ◽  
Environment Model

Abstract. Extratropical cyclones are the most damaging natural hazard to affect western Europe. Serial clustering occurs when many intense cyclones affect one area in a period of time which can potentially lead to very large seasonal losses. Previous studies have shown that intense cyclones may be more likely to cluster than less intense cyclones. We revisit this topic using a high resolution climate model with the aim to determine how important clustering is for windstorm related losses. The role of windstorm clustering is investigated using a quantifiable loss-based metric (storm severity index (SSI)) based on near-surface meteorological variables (10-metre wind speed) that is used to convert a wind footprint into losses for individual windstorms or seasons. 918 years of high resolution coupled climate model data from the High-Resolution Global Environment Model (HiGEM) are compared to ERA-Interim re-analysis. HiGEM is able to successfully reproduce the wintertime North Atlantic/European circulation, and represent the large-scale circulation associated with the serial clustering of European windstorms. We use two measures to identify any changes in the contribution of clustering to the overall seasonal losses for increasing return periods. Above a return period of 3 years, the accumulated seasonal loss from HiGEM is up to 20 % larger than the accumulated seasonal loss from a set of random realisations of the HiGEM data. Seasonsal losses are increased by 10–20 % relative to randomised seasonal losses at a return period of 200 years. The contribution of the single largest event in a season to the accumulated seasonal loss does not change with return period, generally ranging between ~ 0.25–0.5. Given the realistic dynamical representation of cyclone clustering in HiGEM, and comparable statistics to ERA-Interim, we conclude that our estimation of clustering and its dependence on the return period will be useful for informing the development of risk models for European windstorms, particularly for longer return periods.

scholarly journals Supplementary material to "The Kerala flood of 2018: combined impact of extreme rainfall and reservoir storage"

2018 ◽  
Author(s):  
Vimal Mishra ◽  
Saran Aaadhar ◽  
Harsh Shah ◽  
Rahul Kumar ◽  
Dushmanta Ranjan Pattanaik ◽  
...  
Keyword(s):  
Extreme Rainfall ◽  
Reservoir Storage ◽  
Supplementary Material ◽  
Combined Impact

The position of the genitive in Old English prose: Intertextual differences and the role of Latin

2020 ◽  
Vol 54 (s41) ◽  
pp. 1-35
Author(s):  
Anna Cichosz ◽  
Maciej Grabski
Keyword(s):  
Logistic Regression ◽  
Old English ◽  
Large Scale ◽  
Potential Influence ◽  
Corpus Study ◽  
Multiple Variables ◽  
English Syntax ◽  
Bottom To Top ◽  
Combined Impact

Abstract The present article is a systematic, large-scale corpus study of the varying position of the Old English adnominal genitive. Particular focus is put on intertextual variation and the potential influence of Latin, which is analysed alongside such intra-linguistic factors as syntactic weight and the animacy of the referent. The model of logistic regression adopted helps address a key issue in studies on genitive placement, namely, if and how multiple variables exert combined impact on the choice of the variant. The paper highlights the importance of a bottom-to-top approach in studies of older English syntax, as global tendencies turn out to be the corollary of significantly different contributions on the level of individual texts, whose translation status (original composition or translation) is also of importance to the variation studied.

On the subseasonal clustering of European extreme precipitation events and its relationship to large-scale atmospheric drivers

2021 ◽  
Author(s):  
Yannick Barton ◽  
Pauline Rivoire ◽  
Jérôme Kopp ◽  
S. Mubashshir Ali ◽  
Olivia Martius
Keyword(s):  
Extreme Precipitation ◽  
Large Scale ◽  
Extreme Rainfall ◽  
The Arctic ◽  
Extreme Rainfall Events ◽  
Baseline Rate ◽  
Temporal Clustering ◽  
Extreme Precipitation Events ◽  
Western Spain ◽  
Precipitation Events

<p>Extreme precipitation events that occur in close succession can have important societal and economic repercussions. Few studies have investigated the link between large-scale atmospheric drivers and temporal clustering of extreme precipitation events on a subseasonal scale, i.e. 20-day time scale. Here we use 40 years of reanalysis data (ERA-5) to investigate the link between possibly influential atmospheric variables and the temporal clustering of catchment-averaged extreme rainfall events in Europe. We define extreme events as exceedances above the 99th percentile and runs of consecutive days are declustered. We then explicitly model the seasonal rate of extreme occurrences using penalized cubic splines. The smoothed seasonal rate of extremes is then used to (i) infer the significance of subseasonal clustering and (ii) serves as the baseline rate for the subsequent modelling step. We use a Poisson generalized linear model with the baseline rate set as an offset to model the relationship between the temporal clustering and predictor variables. These variables are the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), atmospheric blocks, and a measure of the recurrence of synoptic-scale Rossby wave packets (RRWPs).</p><p>Initial results from four carefully selected catchments reveal the following patterns: for south-western Spain, the NAO, and AO indices tend to be notably lower on significantly clustered extreme rainfall days, whereas for northern Scotland the opposite effect is observed. Also, for south-western Spain, the Greenland atmospheric blocking frequency is significantly enhanced on clustering days. Last, on clustering days in north-western France, Scandinavian blocks are significantly more frequent.</p><p>For a complementary study on a methodology to identify subseasonal clustering episodes of extreme precipitation events and their contribution to large accumulations please refer to Kopp et al.</p>

scholarly journals The SCOUT-O3 Darwin Aircraft Campaign: rationale and meteorology

2008 ◽  
Vol 8 (5) ◽  
pp. 17131-17191 ◽  
Author(s):  
D. Brunner ◽  
P. Siegmund ◽  
P. T. May ◽  
L. Chappel ◽  
C. Schiller ◽  
...  
Keyword(s):  
Large Scale ◽  
Monsoon Season ◽  
Deep Convection ◽  
Cirrus Clouds ◽  
Cold Trap ◽  
Kelvin Wave ◽  
Rossby Wave Breaking ◽  
Tropical Tropopause

Abstract. An aircraft measurement campaign involving the Russian high-altitude aircraft M55 Geophysica and the German DLR Falcon was conducted in Darwin, Australia in November and December 2005 as part of the European integrated project SCOUT-O3. The overall objectives of the campaign were to study the transport of trace gases through the tropical tropopause layer (TTL), mechanisms of dehydration close to the tropopause, and the role of deep convection in these processes. In this paper a detailed roadmap of the campaign is presented, including rationales for each flight, and an analysis of the local and large-scale meteorological context in which they were embedded. The campaign took place during the pre-monsoon season which is characterized by a pronounced diurnal evolution of deep convection including a mesoscale system over the Tiwi Islands north of Darwin known as "Hector". This allowed studying in detail the role of deep convection in structuring the tropical tropopause region, in situ sampling convective overshoots above storm anvils, and probing the structure of anvils and cirrus clouds by Lidar and a suite of in situ instruments onboard the two aircraft. The large-scale flow during the first half of the campaign was such that local flights, away from convection, sampled air masses downstream of the "cold trap" region over Indonesia. Abundant cirrus clouds enabled the study of active dehydration, in particular during two TTL survey flights. The campaign period also encompassed a Rossby wave breaking event transporting stratospheric air to the tropical middle troposphere and an equatorial Kelvin wave modulating tropopause temperatures and hence the conditions for dehydration.

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction
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