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.

scholarly journals TRMM rainfall estimative coupled with Bell (1969) methodology for extreme rainfall characterization

2015 ◽  
Vol 369 ◽  
pp. 163-168 ◽  
Author(s):  
E. Schiavo Bernardi ◽  
D. Allasia ◽  
R. Basso ◽  
P. Freitas Ferreira ◽  
R. Tassi
Keyword(s):  
Temporal Distribution ◽  
Daily Rainfall ◽  
Tropical Rainfall Measuring Mission ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Remote Sensors ◽  
Indirect Measures ◽  
Equation Error ◽  
Convective Cells

Abstract. The lack of rainfall data in Brazil, and, in particular, in Rio Grande do Sul State (RS), hinders the understanding of the spatial and temporal distribution of rainfall, especially in the case of the more complex extreme events. In this context, rainfall's estimation from remote sensors is seen as alternative to the scarcity of rainfall gauges. However, as they are indirect measures, such estimates needs validation. This paper aims to verify the applicability of the Tropical Rainfall Measuring Mission (TRMM) satellite information for extreme rainfall determination in RS. The analysis was accomplished at different temporal scales that ranged from 5 min to daily rainfall while spatial distribution of rainfall was investigated by means of regionalization. An initial test verified TRMM rainfall estimative against measured rainfall at gauges for 1998–2013 period considering different durations and return periods (RP). Results indicated that, for the RP of 2, 5, 10 and 15 years, TRMM overestimated on average 24.7% daily rainfall. As TRMM minimum time-steps is 3 h, in order to verify shorter duration rainfall, the TRMM data were adapted to fit Bell's (1969) generalized IDF formula (based on the existence of similarity between the mechanisms of extreme rainfall events as they are associated to convective cells). Bell`s equation error against measured precipitation was around 5–10%, which varied based on location, RP and duration while the coupled BELL+TRMM error was around 10–35%. However, errors were regionally distributed, allowing a correction to be implemented that reduced by half these values. These findings in turn permitted the use of TRMM+Bell estimates to improve the understanding of spatiotemporal distribution of extreme hydrological rainfall events.

Extreme rainfall events during and following heatwaves

2021 ◽  
Author(s):  
Christoph Sauter ◽  
Christopher White ◽  
Hayley Fowler ◽  
Seth Westra
Keyword(s):  
Natural Hazards ◽  
Rainfall Intensity ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Rainfall Extremes ◽  
Average Rainfall ◽  
Time Of Year ◽  
The Impact

<p>Heatwaves and extreme rainfall events are natural hazards that can have severe impacts on society. The relationship between temperature and extreme rainfall has received scientific attention with studies focussing on how single daily or sub-daily rainfall extremes are related to day-to-day temperature variability. However, the impact multi-day heatwaves have on sub-daily extreme rainfall events and how extreme rainfall properties change during different stages of a heatwave remains mostly unexplored.</p><p>In this study, we analyse sub-daily rainfall records across Australia, a country that experiences severe natural hazards on a frequent basis, and determine their extreme rainfall properties, such as rainfall intensity, duration and frequency during SH-summer heatwaves. These properties are then compared to extreme rainfall properties found outside heatwaves, but during the same time of year, to examine to what extent they differ from normal conditions. We also conduct a spatial analysis to investigate any spatial patterns that arise.</p><p>We find that rainfall breaking heatwaves is often more extreme than average rainfall during the same time of year. This is especially prominent on the eastern and south-eastern Australian coast, where frequency and intensity of sub-daily rainfall extremes show an increase during the last day or the day immediately after a heatwave. We also find that although during heatwaves the average rainfall amount and duration decreases, there is an increase in sub-daily rainfall intensity when compared to conditions outside heatwaves. This implies that even though Australian heatwaves are generally characterised by dry conditions, rainfall occurrences within heatwaves are more intense.</p><p>Both heatwaves and extreme rainfall events pose great challenges for many sectors such as agriculture, and especially if they occur together. Understanding how and to what degree these events co-occur could help mitigate the impacts caused by them.</p>

Extreme rainfall and drought events in Tamil Nadu, India

2020 ◽  
Vol 80 (3) ◽  
pp. 175-188
Author(s):  
R Rajkumar ◽  
CS Shaijumon ◽  
B Gopakumar ◽  
D Gopalakrishnan
Keyword(s):  
Tamil Nadu ◽  
Daily Rainfall ◽  
India Meteorological Department ◽  
Extreme Rainfall ◽  
Drought Severity ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Significance Level ◽  
Spatio Temporal ◽  
Temporal Dimensions

In the present study, we examined the exposure of the Tamil Nadu region, India, to droughts and extreme rainfall events using the Standardised Precipitation Evapotranspiration Index (SPEI) and a classification scheme based on daily rainfall. We used high-resolution temperature and rainfall observations from the India Meteorological Department for the period 1951-2016. The robustness of the results was tested using the Mann-Kendall trend (M-K) test and the Kolmogorov-Smirnov (K-S) test. During the study period, there were statistically significant increasing trends in drought area (90% significance level), maximum drought intensity (99% significance level) and maximum drought severity (99% significance level) over the Tamil Nadu region. There has also been an increase in the frequency and intensity of heavy rainfall events in recent years. The spatio-temporal dimensions of this study suggest an increasing exposure of this semi-arid, rain shadow region to severe droughts and extreme rainfall events in recent decades. The results provide sufficient grounds to substantiate the necessity of immediate interventions at the policy level.

scholarly journals The impact of atmospheric rivers on rainfall in New Zealand

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jingxiang Shu ◽  
Asaad Y. Shamseldin ◽  
Evan Weller
Keyword(s):  
New Zealand ◽  
Austral Summer ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Detection Algorithm ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Atmospheric Rivers ◽  
Hydrological Hazards ◽  
The Impact

AbstractThis study quantifies the impact of atmospheric rivers (ARs) on rainfall in New Zealand. Using an automated AR detection algorithm, daily rainfall records from 654 rain gauges, and various atmospheric reanalysis datasets, we investigate the climatology of ARs, the characteristics of landfalling ARs, the contribution of ARs to annual and seasonal rainfall totals, and extreme rainfall events between 1979 and 2018 across the country. Results indicate that these filamentary synoptic features play an essential role in regional water resources and are responsible for many extreme rainfall events on the western side of mountainous areas and northern New Zealand. In these regions, depending on the season, 40–86% of the rainfall totals and 50–98% of extreme rainfall events are shown to be associated with ARs, with the largest contributions predominantly occurring during the austral summer. Furthermore, the median daily rainfall associated with ARs is 2–3 times than that associated with other storms. The results of this study extend the knowledge on the critical roles of ARs on hydrology and highlight the need for further investigation on the landfalling AR physical processes in relation to global circulation features and AR sources, and hydrological hazards caused by ARs in New Zealand.

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 Extreme Daily Rainfall in Central-Southern Chile and Its Relationship with Low-Level Horizontal Water Vapor Fluxes

2019 ◽  
Vol 20 (9) ◽  
pp. 1829-1850 ◽  
Author(s):  
Raúl A. Valenzuela ◽  
René D. Garreaud
Keyword(s):  
Water Vapor ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Southern Chile ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Rain Gauges ◽  
The Andes ◽  
Synoptic Forcing ◽  
Moisture Fluxes

AbstractExtreme rainfall events are thought to be one of the major threats of climate change given an increase of water vapor available in the atmosphere. However, before projecting future changes in extreme rainfall events, it is mandatory to know current patterns. In this study we explore extreme daily rainfall events along central-southern Chile with emphasis in their spatial distribution and concurrent synoptic-scale circulation. Surface rain gauges and reanalysis products from the Climate Forecast System Reanalysis are employed to unravel the dependency between extreme rainfall and horizontal water vapor fluxes. Results indicate that extreme rainfall events can occur everywhere, from the subtropical to extratropical latitudes, but their frequency increases where terrain has higher altitude, especially over the Andes Mountains. The majority of these events concentrate in austral winter, last a single day, and encompass a north–south band of about 200 km in length. Composited synoptic analyses identified extreme rainfall cases dominated by northwesterly (NW) and westerly (W) moisture fluxes. Some features of the NW group include a 300-hPa trough projecting from the extratropics to subtropics, a surface-level depression, and cyclonic winds at 850 hPa along the coast associated with integrated water vapor (IWV) > 30 mm. Conversely, features in the W group include both a very weak 300-hPa trough and surface depression, as well as coastal westerly winds associated with IWV > 30 mm. About half of extreme daily rainfall is associated with an atmospheric river. Extreme rainfall observed in W (NW) cases has a strong orographic (synoptic) forcing. In addition, W cases are, on average, warmer than NW cases, leading to an amplified hydrological response.

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 Impacts of the Madden-Julian Oscillation (MJO) on rainfall in Sri Lanka

MAUSAM ◽  
2021 ◽  
Vol 71 (3) ◽  
pp. 405-422
Author(s):  
JAYAWARDENA I M SHIROMANI PRIYANTHIKA ◽  
WHEELER MATTHEW C ◽  
SUMATHIPALA W L ◽  
BASNAYAKE B R S B
Keyword(s):  
Sri Lanka ◽  
Large Scale ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Southwest Monsoon ◽  
Boreal Winter ◽  
Northeast Monsoon ◽  
Madden Julian Oscillation ◽  
Extreme Rainfall Events ◽  
Rainfall Events

The influence of the Madden Julian Oscillation (MJO) on rainfall in Sri Lanka (SL) is examined based on 30 years of daily station data from 1981-2010. Composites are constructed for each of the eight phases of the MJO defined with the Real-time Multivariate MJO (RMM) index, using daily rainfall data from 44 stations over SL for four climatic seasons and comparing to similar results from a satellite-based rainfall product. Composites of lower tropospheric wind and convective anomaly are also investigated in order to examine how the local rainfall anomalies are associated with large-scale circulations. The greatest impact of the MJO on rainfall over SL occurs in the Second Inter-Monsoon (SIM) and Southwest Monsoon (SWM) seasons. Enhanced rainfall generally occurs over SL during RMM phases 2 and 3 when the MJO convective envelop is located in the Indian Ocean and conversely suppressed rainfall in phases 6 and 7. This rainfall impact is due to the direct influence of the MJO’s tropical convective anomalies and associated low-level circulations in the vicinity of SL. In contrast, the MJO influence during the Northeast Monsoon (NEM) season is slightly less than during the SWM and SIM seasons as a result of the southward shift of the MJO convective envelop during boreal winter. Occurrence of extreme rainfall events is most frequent during phase 2 in First Inter-Monsoon (FIM) phases 2 and 3 in SWM, phases 1, 2 and 3 in SIM and phases 2 and 3 in NEM seasons. The analysis of this study provides a useful reference of when and where the MJO has significant impacts on rainfall as well as extreme rainfall events during four climatic seasons in SL. This information can be used along with accurately predicted MJO phase by dynamical or statistical models, to improve extended range forecasting in SL.

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