scholarly journals Extreme rainfall events in the Northeastern USA become more frequent with rising temperatures, but their intensity distribution remains stable

2021 ◽  
pp. 1-51
Author(s):  
Helga Kristin Olafsdottir ◽  
Holger Rootzén ◽  
David Bolin
Keyword(s):  
Extreme Rainfall ◽  
Rain Gauge ◽  
Series Data ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Daily Data ◽  
Extreme Value Model ◽  
Value Model ◽  
Increasing Trends ◽  
Northeastern Usa

AbstractBoth intensities of individual extreme rainfall events and the frequency of such events are important for infrastructure planning. We develop a new statistical extreme value model, the PGEV model, which makes it possible to use high quality annual maximum series data instead of lesswell checked daily data to estimate trends in intensity and frequency separately. The method is applied to annual maxima data from the NOAA Atlas 14, Volume 10, dating from approximately 1900 to 2014, showing that in the majority of 333 rain gauge stations in the Northeastern USA the frequency of extreme rainfall events increases as mean temperature increases, but that there is little evidence of trends in the distribution of the intensities of individual extreme rainfall events. The median of the frequency trends corresponds to extreme rainfalls becoming 83% more frequent for each centigrade degree of temperature increase. Naturally, increasing trends in frequency also increase the yearly or 10-yearly risks of very extreme rainfall events. Three other large areas in the contiguous USA, the Midwest, the Southeast, and Texas, are also studied, and show similar but weaker trends than those in the Northeast.

scholarly journals Trends in the Frequency of Intense Precipitation Events in Southern and Southeastern Brazil during 1960–2004

2011 ◽  
Vol 24 (7) ◽  
pp. 1913-1921 ◽  
Author(s):  
Mateus da Silva Teixeira ◽  
Prakki Satyamurty
Keyword(s):  
Extreme Rainfall ◽  
Southeastern Brazil ◽  
Extreme Rainfall Event ◽  
Southern Brazil ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Annual Frequency ◽  
Long Term Trends ◽  
Increasing Trends

Abstract A new approach to define heavy and extreme rainfall events based on cluster analysis and area-average rainfall series is presented. The annual frequency of the heavy and extreme rainfall events is obtained for the southeastern and southern Brazil regions. In the 1960–2004 period, 510 (98) and 466 (77) heavy (extreme) rainfall events are identified in the two regions. Monthly distributions of the events closely follow the monthly climatological rainfall in the two regions. In both regions, annual heavy and extreme rainfall event frequencies present increasing trends in the 45-yr period. However, only in southern Brazil is the trend statistically significant. Although longer time series are necessary to ensure the existence of long-term trends, the positive trends are somewhat alarming since they indicate that climate changes, in terms of rainfall regimes, are possibly under way in Brazil.

scholarly journals Extreme Rainfall in the Mediterranean: What Can We Learn from Observations?

2013 ◽  
Vol 14 (3) ◽  
pp. 906-922 ◽  
Author(s):  
N. Rebora ◽  
L. Molini ◽  
E. Casella ◽  
A. Comellas ◽  
E. Fiori ◽  
...  
Keyword(s):  
Extreme Rainfall ◽  
Flash Floods ◽  
Rain Gauge ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Life Threatening ◽  
The Mediterranean ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Ground Effects

Abstract Flash floods induced by extreme rainfall events represent one of the most life-threatening phenomena in the Mediterranean. While their catastrophic ground effects are well documented by postevent surveys, the extreme rainfall events that generate them are still difficult to observe properly. Being able to collect observations of such events will help scientists to better understand and model these phenomena. The recent flash floods that hit the Liguria region (Italy) between the end of October and beginning of November 2011 give us the opportunity to use the measurements available from a large number of sensors, both ground based and spaceborne, to characterize these events. In this paper, the authors analyze the role of the key ingredients (e.g., unstable air masses, moist low-level jets, steep orography, and a slow-evolving synoptic pattern) for severe rainfall processes over complex orography. For the two Ligurian events, this role has been analyzed through the available observations (e.g., Meteosat Second Generation, Moderate Resolution Imaging Spectroradiometer, the Italian Radar Network mosaic, and the Italian rain gauge network observations). The authors then address the possible role of sea–atmosphere interactions and propose a characterization of these events in terms of their predictability.

scholarly journals Improving an Extreme Rainfall Detection System with GPM IMERG data

2019 ◽  
Vol 11 (6) ◽  
pp. 677 ◽  
Author(s):  
Paola Mazzoglio ◽  
Francesco Laio ◽  
Simone Balbo ◽  
Piero Boccardo ◽  
Franca Disabato
Keyword(s):  
Detection System ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Probability Of Detection ◽  
Mean Annual Precipitation ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Time Aggregation ◽  
Spatial Coverage ◽  
Rainfall Detection

Many studies have shown a growing trend in terms of frequency and severity of extreme events. As never before, having tools capable to monitor the amount of rain that reaches the Earth’s surface has become a key point for the identification of areas potentially affected by floods. In order to guarantee an almost global spatial coverage, NASA Global Precipitation Measurement (GPM) IMERG products proved to be the most appropriate source of information for precipitation retrievement by satellite. This study is aimed at defining the IMERG accuracy in representing extreme rainfall events for varying time aggregation intervals. This is performed by comparing the IMERG data with the rain gauge ones. The outcomes demonstrate that precipitation satellite data guarantee good results when the rainfall aggregation interval is equal to or greater than 12 h. More specifically, a 24-h aggregation interval ensures a probability of detection (defined as the number of hits divided by the total number of observed events) greater than 80%. The outcomes of this analysis supported the development of the updated version of the ITHACA Extreme Rainfall Detection System (ERDS: erds.ithacaweb.org). This system is now able to provide near real-time alerts about extreme rainfall events using a threshold methodology based on the mean annual precipitation.

 Evaluation of high resolution WRF forecasts for Extreme Rainfall Events over Karnataka against high density in-situ observations 

2021 ◽  
Author(s):  
Ajay Bankar ◽  
Rakesh Vasudevan
Keyword(s):  
Prediction Models ◽  
Initial Conditions ◽  
Weather Prediction ◽  
Wrf Model ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Distinct Advantage ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Synoptic Conditions

<p><span>Extreme Rainfall Events (EREs) in India has increased many folds in recent decades. These severe weather events are generally destructive in nature causing flash floods, catastrophic loss of life and property over densely populated urban cities. Various cities in Karnataka, a southern state in India, witnessed many EREs recently. Appropriate advanced warning systems to predict these events are crucial for preparedness of mitigation strategy to reduce human casualty and socio economic loss. Mesoscale models are essential tools for developing an integrated platform for disaster warning and management. From a stakeholder/user pint of view, primary requirement to tackle ERE related damages is accurate prediction of the observed rainfall location, coverage and intensity in advance. Weather prediction models have inherent limitations imposed primarily by approximations in the model and inadequacies in data. Hence, it is important to evaluate the skill of these models for many cases under different synoptic conditions to quantify model skill before using them for operational applications. The objective of the study is to evaluate performance of the Weather Research and Forecasting (WRF) model for several ERE cases in Karnataka at different model initial conditions. The EREs were identified from the distribution of rainfall events over different regions in Karnataka and those events comes under 1% probability were considered. We examined 38 ERE’s distributed over Karnataka for the period June to November for the years 2015-2019. WRF model is configured with 3 nested domains with outer, inner and innermost domains having resolution of 12 km, 9 km and 3 km respectively. Two sets of simulations are conducted in this study, i) staring at 12 hours prior to the ERE day (i.e. -1200 UTC) & ii) starting at 0000 UTC of the ERE day. Performance of the WRF model forecast is validated against 15 minutes rainfall observations from ~6000 rain gauge stations over Karnataka. During initial hours forecasts initiated at 1200 UTC has distinct advantage in terms of accuracy compared to those initiated at 0000 UTC for most of the cases. In general, model underpredict EREs and underprediction is relatively low for forecasts initiated at 12 00 UTC.</span></p>

scholarly journals Addressing Climate Internal Variability on Future Intensity-Duration-Frequency Curves at Fine Scales across South Korea

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2828
Author(s):  
Manh Van Doi ◽  
Jongho Kim
Keyword(s):  
South Korea ◽  
Time Series Data ◽  
Extreme Rainfall ◽  
Internal Variability ◽  
Series Data ◽  
Return Periods ◽  
Precipitation Frequency ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Data Length

Designing water infrastructure requires information about the magnitude and frequency of upcoming rainfall. A limited range of data offers just one of many realizations that occurred in the past or will occur in the future; thus, it cannot sufficiently explain climate internal variability (CIV). In this study, future relationships among rainfall intensity (RI), duration, and frequency (called the IDF curve) are established by addressing the CIV and tail characteristics with respect to frequency. Specifically, 100 ensembles of 30-year time series data were created to quantify that uncertainty. Then, the tail characteristics of future extreme rainfall events were investigated to determine whether they will remain similar to those in the present. From the RIs computed for control and future periods under two emission scenarios, following are the key results. Firstly, future RI will increase significantly for most locations, especially near the end of this century. Secondly, the spatial distributions and patterns indicate higher RI in coastal areas and lower RI for the central inland areas of South Korea, and those distributions are similar to those of the climatological mean (CM) and CIV. Thirdly, a straightforward way to reveal whether the tail characteristics of future extreme rainfall events are the same as those in the present is to inspect the slope value for the factor of change (FOC), mFOC. Fourthly, regionalizing with nearby values is very risky when investigating future changes in precipitation frequency estimates. Fifthly, the magnitude of uncertainty is large when the data length is short and gradually decreases as the data length increases for all return periods, but the uncertainty range becomes much greater as the return period becomes large. Lastly, inferring future changes in RI from the CM is feasible only for small return periods and at locations where mFOC is close to zero.

ANALYSIS OF EXTREME RAINFALL INDICES IN PENINSULAR MALAYSIA

2016 ◽  
Vol 78 (9-4) ◽  
Author(s):  
Nur Shazwani Muhammad ◽  
Amieroul Iefwat Akashah ◽  
Jazuri Abdullah
Keyword(s):  
East Coast ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Peninsular Malaysia ◽  
Rainfall Data ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Daily Rainfall Data ◽  
Extreme Rain ◽  
Increasing Trends

Extreme rainfall events are the main cause of flooding. This study aimed to examine seven extreme rainfall indices, i.e. extreme rain sum (XRS), very wet day intensity (I95), extremely wet day intensity (I99), very wet day proportion (R95), extremely wet day proportion (R99), very wet days (N95) and extremely wet days (N99) using Mann-Kendall (MK) and the normalized statistic Z tests. The analyses are based on the daily rainfall data gathered from Bayan Lepas, Subang, Senai, Kuantan and Kota Bharu. The east coast states received more rainfall than any other parts in Peninsular Malaysia. Kota Bharu station recorded the highest XRS, i.e. 648 mm. The analyses also indicate that the stations in the eastern part of Peninsular Malaysia experienced higher XRS, I95, I99, R95 and R99 as compared to the stations located in the western and northern part of Peninsular Malaysia. Subang and Senai show the highest number of days for wet and very wet (N95) as compared to other stations. Other than that, all stations except for Kota Bharu show increasing trends for most of the extreme rainfall indices. Upward trends indicate that the extreme rainfall events were becoming more severe over the period of 1960 to 2014. 

scholarly journals Índices de Detecção de Mudanças Climáticas Derivados da Precipitação Pluviométrica e das Temperaturas em Recife-PE (Detection Indexes Derived from Climate Change Rainfall and Temperatures in Recife-PE)

2012 ◽  
Vol 5 (1) ◽  
pp. 143 ◽  
Author(s):  
Werônica Meira Souza ◽  
Pedro Vieira Azevedo
Keyword(s):  
Climate Change ◽  
Heat Waves ◽  
Global Climate ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Climate Indices ◽  
Extreme Rainfall Events ◽  
Detection Rates ◽  
Rainfall Events ◽  
Daily Data

Este trabalho objetiva verificar as tendências dos índices de detecção de mudanças climáticas derivados da precipitação pluviométrica e das temperaturas máximas e mínimas em Recife, a partir do software RClimdex, com o propósito de averiguar se houve mudanças no comportamento dos elementos climáticos analisados. Foram utilizados dados diários da precipitação pluviométrica e das temperaturas (máximas e mínimas) no período de 1961 a 2008 em Recife, cedidos pelo INMET. Os resultados derivados da precipitação não apresentaram tendências significativas de redução. Por outro lado, diagnosticou-se aumento da frequência de eventos extremos de chuvas a partir da década de 80, com chuvas diárias superiores a 100 mm. Em relação aos índices associados às temperaturas, todos apontam tendências positivas, indicando aumento das temperaturas máximas e mínimas em torno de 1oC nos 47 anos analisados, com aumento da frequência de dias e noites mais quentes, constatando-se aumento de ondas de calor na região. Apesar dos resultados apresentarem mudanças nos índices climáticos, estas alterações não necessariamente estão associadas a uma mudança climática global, mas principalmente as ações antropogências através da modificação do espaço. Palavras-chave: Mudança climática, precipitação pluviométrica, temperaturas, RClimdex.  Detection Indexes Derived from Climate Change Rainfall and Temperatures in Recife-PE  ABSTRACT This study aims to determine the detection rates of climate change derived from rainfall and maximum and minimum temperatures in Recife, through the RClimdex software, with the purpose of investigate whether there were changes in the behavior of climatic elements analyzed. It used daily data of rainfall and temperatures (maximum and minimum) in the period 1961 to 2008 in Recife, assigned by INMET. The results derived from the precipitation did not show significant trends of reduction. On the other hand, was diagnosed with increasing frequency of extreme rainfall events from the 1980, with daily rainfall exceeding 100 mm. Compared to the temperatures associated with, all indicate positive trends, indicating an increase of the maximum and minimum temperatures around 1 °C in 47 years analyzed, with increased frequency of hot days and nights, it noted the increase in heat waves in the region . Although the results present changes in climate indices, these changes are not necessarily associated with global climate change, but mainly through the actions of anthropogenic modification of the space. Keywords: Climate change, rainfall, temperatures, RClimdex.

scholarly journals On the Epochal Strengthening in the Relationship between Rainfall of East Africa and IOD

2013 ◽  
Vol 26 (15) ◽  
pp. 5655-5673 ◽  
Author(s):  
Desmond Manatsa ◽  
Swadhin K. Behera
Keyword(s):  
East Africa ◽  
Rainfall Variability ◽  
Spatial Coherence ◽  
Principal Component ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Monthly Precipitation ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Global Precipitation Climatology Centre

Abstract Variability of the equatorial East Africa “short rains” (EASR) has intensified significantly since the turn of the twentieth century. This increase toward more extreme rainfall events has not been gradual but is strongly characterized by epochs. The rain gauge–based Global Precipitation Climatology Centre (GPCC) monthly precipitation dataset for the period 1901–2009 is used to demonstrate that the epochal changes were dictated by shifts in the Indian Ocean dipole (IOD) mode. These shifts occurred during 1961 and 1997. In the pre-1961 period, there was virtually no significant linear link between the IOD and the EASR. But a relatively strong coupling between the two occurred abruptly in 1961 and was generally maintained at that level until 1997, when another sudden shift to even a greater level occurred. The first principal component (PC1) extracted from the EASR spatial domain initially merely explained about 50% of the rainfall variability before 1961, and then catapulted to about 73% for the period from 1961 to 1997, before eventually shifting to exceed 82% after 1997. The PC1 for each successive epoch also displayed loadings with notably improved spatial coherence. This systematic pattern of increase was accompanied by both a sharp increase in the frequency of rainfall extremes and spatial coherence of the rainfall events over the region. Therefore, it is most likely that the 1961 and 1997 IOD shifts are responsible for the epochal modulation of the EASR in both the spatial and temporal domain.

scholarly journals Variability and trends in extreme rainfall over India

MAUSAM ◽  
2021 ◽  
Vol 67 (4) ◽  
pp. 745-766
Author(s):  
A. K. SRIVASTAVA ◽  
G. P. SINGH ◽  
O. P. SINGH
Keyword(s):  
Rainfall Intensity ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
North Central ◽  
Rainfall Events ◽  
North West ◽  
North East ◽  
Increasing Trends

This study has been attempted to investigate the seasonal and annual trends and variations in the occurrence of extreme rainfall over different Indian region and India as a whole. Trends and variations are examined on the basis of following parameters (i) frequency and magnitude of extreme rainfall intensity (ERI) and its contribution in total rainfall (ii) highest rainfall events (iii) frequency of extreme rainfall events and days (iv) frequency of rainfall events and days with daily rainfall above 100 mm and 200 mm in a grid box (1° × 1°) over different Indian regions and India as a whole. Daily gridded rainfall data from India Meteorological Department (IMD) available at 1° × 1° resolution has been used to examine trends and variations associated with extreme rainfall events. Based on the long term 95 and 99 percentile values of daily total /maximum rainfall as a threshold for extreme rainfall intensity/events of category 1 and category 2 respectively, the trends and variations in above mentioned parameters are analyzed for the periods 1951-2007, 1951-1980 and 1981-2007.  The magnitude of highest intensity rainfall is increased over country as a whole and over peninsular India; it is found to be increased by 1% during 1981-2007 as compared to period 1951-1980. The frequency of extreme rainfall intensity (ERI) days of category 1 is found to be significant increasing (0.4 days/decade) over north central region and significant decreasing trend is found over north east region (0.5 days/decade) during the pre-monsoon season. The magnitude of 24 hours highest rainfall in a grid box is found to be significant increasing over all regions under consideration except over north east and south peninsular regions. Over the last ten years period of the present study, most of the 24 hours highest rainfall events in a grid box are seen over west peninsular region. Generalized extreme value (GEV) distribution fitted with annual highest rainfall event over the country as a whole and over different Indian region indicates an increase in magnitude of most probable 24 hours highest rainfall in a grid box during second half of the  study period over north central region of the country. Analysis also reveals an increase in frequency and severity of extreme rainfall over north west, north central and west peninsular regions during the period of 1981-2007 as compared to 1950-1980.                 Annual frequency of days and events with extreme rainfall of both categories is increased most significantly over country during the period of present study (1951-2007). Significant increasing trends in frequency of days with extreme rainfall of both categories is noticed only during the monsoon season while extreme rainfall events showed increasing trends during monsoon and winter season over country as a whole. Number of days and events with daily rainfall in any grid box above 100 mm and 200 mm is observed to be significantly increased over the country. Out of six regions, significant increasing trends  in annual number of days with rainfall above 100 mm in a grid box is observed over north central and north east  regions and for rainfall above 200 mm significant increase is observed over north west and north central regions.

The Influence of Geographical Factors on Extreme Rainfalls in Lampung Province

2019 ◽  
Vol 1 (1) ◽  
pp. 33
Author(s):  
M Welly
Keyword(s):  
Geographical Location ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Design Flood ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Ungauged Basin ◽  
Flood Discharge ◽  
Design Rainfall ◽  
Geographical Factors

Many people in Indonesia calculate design rainfall before calculating the design flooddischarge. The design rainfall with a certain return period will eventually be convertedinto a design flood discharge by combining it with the characteristics of the watershed.However, the lack of a network of rainfall recording stations makes many areas that arenot hydrologically measured (ungauged basin), so it is quite difficult to know thecharacteristics of rain in the area concerned. This study aims to analyze thecharacteristics of design rainfall in Lampung Province. The focus of the analysis is toinvestigate whether geographical factors influence the design rainfall that occurs in theparticular area. The data used in this study is daily rainfall data from 15 rainfallrecording stations spread in Lampung Province. The method of frequency analysis usedin this study is the Gumbel method. The research shows that the geographical location ofan area does not have significant effect on extreme rainfall events. The effect of risingearth temperatures due to natural exploitation by humans tends to be stronger as a causeof extreme events such as extreme rainfall.Keywords: Influence, geographical, factors, extreme, rainfall.

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