scholarly journals Roles of Synoptic to Quasi-Biweekly Disturbances in Generating the Summer 2003 Heavy Rainfall in East China

2014 ◽  
Vol 142 (2) ◽  
pp. 886-904 ◽  
Author(s):  
Hong-Bo Liu ◽  
Jing Yang ◽  
Da-Lin Zhang ◽  
Bin Wang
Keyword(s):  
Heavy Rainfall ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Dominant Frequency ◽  
The Philippines ◽  
The Tibetan Plateau ◽  
Synoptic Scale ◽  
Extreme Rainfall Events ◽  
Anticyclonic Anomaly ◽  
Huai River

Abstract During the mei-yu season of the summer of 2003, the Yangtze and Huai River basin (YHRB) encountered anomalously heavy rainfall, and the northern YHRB (nYHRB) suffered a severe flood because of five continuous extreme rainfall events. A spectral analysis of daily rainfall data over YHRB reveals two dominant frequency modes: one peak on day 14 and the other on day 4 (i.e., the quasi-biweekly and synoptic-scale mode, respectively). Results indicate that the two scales of disturbances contributed southwesterly and northeasterly anomalies, respectively, to the mei-yu frontal convergence over the southern YHRB (sYHRB) at the peak wet phase. An analysis of bandpass-filtered circulations shows that the lower and upper regions of the troposphere were fully coupled at the quasi-biweekly scale, and a lower-level cyclonic anomaly over sYHRB was phase locked with an anticyclonic anomaly over the Philippines. At the synoptic scale, the strong northeasterly components of an anticyclonic anomaly with a deep cold and dry layer helped generate the heavy rainfall over sYHRB. Results also indicate the passages of five synoptic-scale disturbances during the nYHRB rainfall. Like the sYHRB rainfall, these disturbances originated from the periodical generations of cyclonic and anticyclonic anomalies at the downstream of the Tibetan Plateau. The nYHRB rainfalls were generated as these disturbances moved northeastward under the influence of monsoonal flows and higher-latitude eastward-propagating Rossby wave trains. It is concluded that the sYHRB heavy rainfall resulted from the superposition of quasi-biweekly and synoptic-scale disturbances, whereas the intermittent passages of five synoptic-scale disturbances led to the flooding rainfall over nYHRB.

Impacts of convectively coupled equatorial waves on rainfall extremes in Java, Indonesia

2021 ◽  
Author(s):  
Muhamad Reyhan Respati ◽  
Sandro W. Lubis
Keyword(s):  
Heavy Rainfall ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Moisture Flux ◽  
Kelvin Waves ◽  
Equatorial Waves ◽  
Multiple Wave ◽  
Extreme Rainfall Events ◽  
Convectively Coupled Equatorial Waves ◽  
Rainfall Extremes

<p>Rainfall extremes cause significant socioeconomic impacts in Indonesia, as they are often followed by disastrous events, such as floods and landslides. Of particular interest is Java Island, the most populated region in Indonesia, which is prone to damaging flooding as a result of heavy rainfall. The prediction of rainfall extremes in this region has mainly been focused on the effects of seasonal and intraseasonal variability, such as monsoons and the Madden–Julian Oscillation. Here, using an extensive station database from 1987 to 2017 and the gridded Asian Precipitation‐Highly Resolved Observational Data Integration Toward Evaluation of Water Resources (APHRODITE) product from 1980 to 2007, we show that severe weather conditions associated with rainfall extremes in Java during the rainy season (November to April) can also be attributed to convectively coupled equatorial waves (CCEWs) that occur on a shorter time scale.</p><p>Evidence is presented that CCEWs, including Kelvin, equatorial Rossby (ER), and mixed Rossby‐gravity (MRG) waves, significantly modulate daily rainfall extremes over Java Island. Of these three types, the Kelvin waves have the greatest influence on heavy rainfall over Java Island. The convectively active (suppressed) phases of Kelvin waves increase (decrease) the probability of extreme rain events over land regions by up to 60% (50%) of the baseline probability. On the other hand, the convectively active phases of ER (MRG) waves increase the probability by up to 45% (40%), while the suppressed phases decrease this by up to 40% (30%). In terms of the mechanism of rainfall extremes, CCEWs modulate moisture flux convergence, leading to the enhancement of local convection over the region. In addition, the analysis of multiple wave events indicates that positive (negative) interferences of the CCEWs lead to an amplification (suppression) of extreme rainfall probability. Overall, the results suggest that equatorial waves provide an important source of the predictability for daily extreme rainfall events over Java Island.</p><p><strong><span>Reference:</span></strong></p><p><span>Lubis, SW</span>, <span>Respati, MR</span>. <span>Impacts of convectively coupled equatorial waves on rainfall extremes in Java, Indonesia</span>. <em>Int J Climatol</em>. <span>2020</span>; <span>1</span>– <span>23</span>. </p><p> </p>

scholarly journals Extreme rainfall events over Odisha state, India

MAUSAM ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 131-138
Author(s):  
S. PASUPALAK ◽  
G. PANIGRAHI ◽  
T. PANIGRAHI ◽  
S. MOHANTY ◽  
K. K. SINGH
Keyword(s):  
Heavy Rainfall ◽  
Hot Spot ◽  
Daily Rainfall ◽  
India Meteorological Department ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Rainfall Frequency ◽  
Before And After ◽  
Block Level

Extreme rainfall events are a significant cause of loss of life and livelihoods in Odisha. Objectives of the present study are to determine the trend of the extreme rainfall events during 1991-2014 and to compare the events between two periods before and after 1991. Block level daily rainfall data were used in identifying the extreme rainfall events, while district level aggregation was used in analysing the trend   in three categories, viz., heavy, very heavy and extremely heavy rainfall as per criteria given by India Meteorological Department (IMD). The state as a whole received one extremely heavy, nine very heavy, and forty heavy rainfall events in a year. When percentage of occurrence of each category out of the total extreme events over different districts was considered, maximum % of extremely heavy rainfall occurred in Kalahandi (5.8%), very heavy rainfall in Bolangir (23.8%) and heavy rainfall in Keonjhargarh (85.4%). Trend analysis showed that number of extreme rainfall events increased in a few districts, namely, Bolangir, Nuapada, Keonjhargarh, Koraput, Malkangiri, and Nawarangapur and did not change in other districts. In Puri district, extremely heavy rainfall frequency decreased. New all-time record high one-day rainfall events were observed in twenty districts during 1992 to 2014, surpassing the earlier records, which could be attributed to  climate change induced by  global warming. Interior south Odisha was found as the hot spot for extreme rainfalls.

Extreme Rainfall Events in the Hawaiian Islands

2009 ◽  
Vol 48 (3) ◽  
pp. 502-516 ◽  
Author(s):  
Pao-Shin Chu ◽  
Xin Zhao ◽  
Ying Ruan ◽  
Melodie Grubbs
Keyword(s):  
Return Period ◽  
Heavy Rainfall ◽  
Hawaiian Islands ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Generalized Extreme Value Distribution ◽  
Economic Losses ◽  
Return Periods ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Abstract Heavy rainfall and the associated floods occur frequently in the Hawaiian Islands and have caused huge economic losses as well as social problems. Extreme rainfall events in this study are defined by three different methods based on 1) the mean annual number of days on which 24-h accumulation exceeds a given daily rainfall amount, 2) the value associated with a specific daily rainfall percentile, and 3) the annual maximum daily rainfall values associated with a specific return period. For estimating the statistics of return periods, the three-parameter generalized extreme value distribution is fit using the method of L-moments. Spatial patterns of heavy and very heavy rainfall events across the islands are mapped separately based on the aforementioned three methods. Among all islands, the pattern on the island of Hawaii is most distinguishable, with a high frequency of events along the eastern slopes of Mauna Kea and a low frequency of events on the western portion so that a sharp gradient in extreme events from east to west is prominent. On other islands, extreme rainfall events tend to occur locally, mainly on the windward slopes. A case is presented for estimating return periods given different rainfall intensity for a station in Upper Manoa, Oahu. For the Halloween flood in 2004, the estimated return period is approximately 27 yr, and its true value should be no less than 13 yr with 95% confidence as determined from the adjusted bootstrap resampling technique.

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.

scholarly journals ­Trends and Zonal Variability of Extreme Rainfall Events Over East Africa During 1960-2017

2021 ◽  
Author(s):  
Moses.A Ojara ◽  
Yunsheng Lou ◽  
Hasssen Babaousmail ◽  
Peter Wasswa
Keyword(s):  
Extreme Events ◽  
Heavy Rainfall ◽  
Rainwater Harvesting ◽  
Southern Oscillation ◽  
Extreme Rainfall ◽  
Mitigation Measures ◽  
Fluctuation Analysis ◽  
Positive Trend ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Abstract East African countries (Uganda, Kenya, Tanzania, Rwanda, and Burundi) are prone to weather extreme events. In this regard; the past occurrence of extreme rainfall events is analyzed for 25 stations following the Expert Team on Climate Change Detection and Indices (ETCCDI) regression method. Detrended Fluctuation Analysis (DFA) is used to show the future development of extreme events. Pearson’s correlation analysis is performed to show the relationship of extreme events between different rainfall zones and their association with El Niño -Southern Oscillation (ENSO and Indian Ocean dipole (IOD) IOD-DMI indices. Results revealed that the consecutive wet day's index (CWD) was decreasing trend in 72% of the stations analyzed, moreover consecutive dry days (CDD) index also indicated a positive trend in 44% of the stations analyzed. Heavy rainfall days index (R10mm) showed a positive trend at 52% of the stations and was statistically significant at a few stations. In light of the extremely heavy rainfall days (R25mm) index, 56% of the stations revealed a decreasing trend for the index and statistically significant trend at some stations. Further, a low correlation coefficient of extreme rainfall events in the regions; and between rainfall extreme indices with the atmospheric teleconnection indices (Dipole Mode Index-DMI and Nino 3.4) (r = -0.1 to r = 0.35). Most rainfall zones showed a positive correlation between the R95p index and DMI, while 5/8 of the rainfall zones experienced a negative correlation between Nino 3.4 index and the R95p. In light of the highly variable trends of extremes events, we recommend planning adaptation and mitigation measures that consider the occurrence of such high variability. Measures such as rainwater harvesting, stored and used during needs, planned settlement, and improved drainage systems management supported by accurate climate and weather forecasts is highly advised.

scholarly journals Bayesian objective classification of extreme UK daily rainfall for flood risk applications

2008 ◽  
Vol 5 (6) ◽  
pp. 3033-3060 ◽  
Author(s):  
M. A. Little ◽  
H. J. E. Rodda ◽  
P. E. McSharry
Keyword(s):  
Flood Risk ◽  
Clustering Algorithm ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Spatial Layout ◽  
Past Century ◽  
Extreme Rainfall Events ◽  
Typing Scheme ◽  
Objective Classification ◽  
Flood Simulations

Abstract. In this study we describe an objective classification scheme for extreme UK daily precipitation to be used in flood risk analysis applications. We create a simplified representation of the spatial layout of extreme events based on a new digital archive of UK rainfall. This simplification allows a Bayesian clustering algorithm to compress these representations down to eight prototypical patterns of extreme falls. These patterns are then verified against a five-class, manual, subjective typing scheme, produced independently using known meteorological mechanisms, isohyetal maps and additional descriptive text from the archive. Compared against the manual scheme, the new objective scheme can reproduce the known meteorological conditions, both in terms of spatial layout and seasonal timing, and is shown to be of hydrological relevance when matched to several notable flooding events in the past century. Furthermore, it is computationally simple and straightforward to apply in classifying future extreme rainfall events. We discuss the practical use of this new typing scheme in flood simulations and climate change applications.

scholarly journals One-Dimensional (1D) River Analysis of a River Basin in Southern Luzon Island in the Philippines Using Lidar Digital Elevation Model

2018 ◽  
Vol 7 (3.7) ◽  
pp. 29
Author(s):  
Fibor J. Tan ◽  
Edgardo Jade R. Rarugal ◽  
Francis Aldrine A. Uy
Keyword(s):  
Digital Elevation Model ◽  
Flood Hazard ◽  
Monsoon Season ◽  
Extreme Rainfall ◽  
The Philippines ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
One Dimensional ◽  
Digital Elevation ◽  
Elevation Model

Flooding is a perennial problem in the Philippines during the monsoon season intensified by the effects of typhoon. On average, there are 20 typhoons that enter the Philippine Area of Responsibility (PAR), and many of these make landfall causing catastrophic aftermath. Extreme rainfall events could lead to flooding in the downstream floodplain and landslide in mountainous terrains. In this study, which is for the case of Calumpang River that drains to the populated and developing region of Batangas City, the focus is on flooding in the floodplain areas. The river was modelled using LiDAR digital elevation model (DEM) that has an accuracy of 20cm in the vertical and 50cm in the horizontal. The result of this is river hydraulic model that can be used to accurately generate flood inundation simulations and flood hazard maps.  

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>

Sign in / Sign up

Export Citation Format

Share Document