Synoptic Situations of Extreme Hourly Precipitation over China

2016 ◽  
Vol 29 (24) ◽  
pp. 8703-8719 ◽  
Author(s):  
Yali Luo ◽  
Mengwen Wu ◽  
Fumin Ren ◽  
Jian Li ◽  
Wai-Kin Wong
Keyword(s):  
Regional Distribution ◽  
Extreme Rainfall ◽  
Northern China ◽  
Rain Gauge ◽  
Synoptic Type ◽  
Shear Line ◽  
Hourly Precipitation ◽  
The North ◽  
Hourly Rainfall ◽  
Reflectivity Data

Abstract In this study, synoptic situations associated with extreme hourly precipitation over China are investigated using rain gauge data, weather maps, and composite radar reflectivity data. Seasonal variations of hourly precipitation (>0.1 mm h−1) suggest complicated regional features in the occurrence frequency and intensity of rainfall. The 99.9th percentile is thus used as the threshold to define the extreme hourly rainfall for each station. The extreme rainfall is the most intense over the south coastal areas and the North China Plain. About 77% of the extreme rainfall records occur in summer with a peak in July (30.4%) during 1981–2013. Nearly 5800 extreme hourly rainfall records in 2011–15 are classified into four types according to the synoptic situations under which they occur: the tropical cyclone (TC), surface front, vortex/shear line, and weak-synoptic forcing. They contribute 8.0%, 13.9%, 39.1%, and 39.0%, respectively, to the total occurrence and present distinctive characteristics in regional distribution and seasonal or diurnal variations. The TC type occurs most frequently along the coasts and decreases progressively toward inland China; the frontal type is distributed relatively evenly east of 104°E; the vortex/shear line type shows a prominent center over the Sichuan basin with two high-frequency bands extending from the center southeastward and northeastward, respectively; and the weak-synoptic type occurs more frequently in southeast, southwest, and northern China, and in the easternmost area of northeast China. Occurrences of the weak-synoptic type have comparable contributions from mesoscale convective systems and smaller-scale storms with notable differences in their preferred locations.

Gridded Hourly Precipitation Analysis from High-Density Rain Gauge Network over the Yangtze–Huai Rivers Basin during the 2007 Mei-Yu Season and Comparison with CMORPH

2013 ◽  
Vol 14 (4) ◽  
pp. 1243-1258 ◽  
Author(s):  
Yali Luo ◽  
Weimiao Qian ◽  
Renhe Zhang ◽  
Da-Lin Zhang
Keyword(s):  
Heavy Rainfall ◽  
Rain Gauge ◽  
Rainfall Analysis ◽  
Hourly Precipitation ◽  
Spatial Consistency ◽  
Hourly Rainfall ◽  
Reflectivity Data ◽  
Climate Prediction Center ◽  
Rain Gauge Network

Abstract Heavy rainfall hit the Yangtze–Huai Rivers basin (YHRB) of east China several times during the prolonged 2007 mei-yu season, causing the worst flood since 1954. There has been an urgent need for attaining and processing high-quality, kilometer-scale, hourly rainfall data in order to understand the mei-yu precipitation processes, especially at the mesoβ and smaller scales. In this paper, the authors describe the construction of the 0.07°-resolution gridded hourly rainfall analysis over the YHRB region during the 2007 mei-yu season that is based on surface reports at 555 national and 6572 regional automated weather stations with an average resolution of about 7 km. The gridded hourly analysis is obtained using a modified Cressman-type objective analysis after applying strict quality control, including not only the commonly used internal temporal and spatial consistency and extreme value checks, but also verifications against mosaic radar reflectivity data. This analysis reveals many convectively generated finescale precipitation structures that could not be seen from the national station reports. A comprehensive quantitative assessment ensures the quality of the gridded hourly precipitation data. A comparison of this dataset with the U.S. Climate Prediction Center morphing technique (CMORPH) dataset on the same resolution suggests the dependence of the latter's performance on different rainfall intensity categories, with substantial underestimation of the magnitude and width of the mei-yu rainband as well as the nocturnal and morning peak rainfall amounts, due mainly to its underestimating the occurrences of heavy rainfall (i.e., >10 mm h−1).

scholarly journals Wavelet Filter Approach andZ-RRelationship in Meteorological Forecasting

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Wallop Jiwlong ◽  
Anongrit Kangrang
Keyword(s):  
Rain Gauge ◽  
Wavelet Filter ◽  
Filtration Process ◽  
Wavelet Filters ◽  
Calibration And Validation ◽  
Filter Technique ◽  
Proposed Model ◽  
Hourly Rainfall ◽  
Filter Approach ◽  
Reflectivity Data

The purpose of this study is to investigate theZ-Rrelationship for computing rainfall using conventional and wavelet filters technique. Wavelet filter technique was applied to data filtration process. The proposed model was applied to determine the rainfall of five rain gauge meteorological stations in Thailand. The three-hourly rainfall and radar reflectivity data were used in this study. The results indicated that the accumulative rainfall of wavelet filters technique was close to the observed rainfall data more than the results of conventional practice for both calibration and validation processes. Consequently, we are confident that a wavelet filters technique is a useful tool for estimating the rainfall.

scholarly journals Sub-daily extreme events distribution and changes in Northeastern Brazil in the 20th century

2015 ◽  
Vol 369 ◽  
pp. 135-140 ◽  
Author(s):  
R. Basso ◽  
D. Allasia ◽  
R. Tassi ◽  
D. M. Bayer
Keyword(s):  
20Th Century ◽  
Extreme Events ◽  
Regional Analysis ◽  
Extreme Rainfall ◽  
Northeastern Brazil ◽  
The North ◽  
Hourly Rainfall ◽  
Northern Portion ◽  
Intensity Duration Frequency ◽  
Engineering Projects

Abstract. The regional analysis of extreme hydrological events is connected with the availability of a dense network of rainfall data that is absent or inaccessible in Brazil, especially for sub-daily information. In engineering, extreme events rainfall information is represented by intensity–duration–frequency (IDF) relationships which are the most commonly used tools in water resources engineering for planning and design. Even if the sub-daily information that is included in the relationships is not available, the extreme rainfall information rest in the fundamentals of the IDF. This paper analyzes spatial distribution and track changes in sub-daily precipitation over Northeastern (NE) Brazil. Precipitation was estimated from IDF relationships information in Brazil based in rainfall measured from 1920's to 1950's (but still used in engineering projects) and information from the last half of the 20th century obtained from several IDFs gathered from municipalities' manuals, local symposia and books in many cases not easily obtainable. Results showed an intensification of extreme events in recent years, especially in shorter duration rainfall (less than 12 h). Hourly rainfall is bigger in almost all the Brazilian region, but especially in littoral and Northern portion, however, 12 and 24 h rainfall exhibit increases in the North, but, lower values in the Southern half of the region in concordance with flood changes reported by Milly et al. (2005). Analyzing the ratio between 1 and 24 h rainfall is possible to confirm its increase in all the region, with up to 35% in some areas. These results were able to show insight of sub-daily extreme events changes during 20th century in NE Brazil were previous reports were not found. The results also alerts for the necessity of engineering projects review, as outdated information is still being used for design purposes.

scholarly journals Dynamical Mechanisms Supporting Extreme Rainfall Accumulations in the Houston “Tax Day” 2016 Flood

2019 ◽  
Vol 148 (1) ◽  
pp. 83-109 ◽  
Author(s):  
Erik R. Nielsen ◽  
Russ S. Schumacher
Keyword(s):  
Rain Rate ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Intense Rainfall ◽  
Convective Rainfall ◽  
Short Term ◽  
Low Level ◽  
Hourly Rainfall ◽  
Scale Characteristics ◽  
Extreme Rain

Abstract This research examines the environmental and storm-scale characteristics of the extreme rainfall and flooding in the Houston, Texas, area on 18 April 2016, known as the “Tax Day” flood. Radar and local mesonet rain gauge observations were used to identify the locations and structures of extreme rain-rate-producing cells, with special attention given to rotating updrafts. To supplement this observation-based analysis, a WRF-ARW simulation of the Tax Day storm in 2016 was examined for the influence of any attendant rotation on both the dynamics and microphysics of the cells producing the most intense short-term (i.e., subhourly to hourly) rainfall accumulations. Results show that the most intense rainfall accumulations in the model analysis, as in the observational analysis, are associated with rotating convective elements. A lowering of the updraft base, enhancement of the low-level vertical velocities, and increased low-level rainwater production is seen in rotating updrafts, compared to those without rotation. These differences are also maintained despite increased hydrometeor loading. The results agree with the findings of previous idealized model simulations that show dynamical accelerations associated with meso-γ-scale rotation can enhance convective rainfall rates.

A formula for downscaling extreme sub-daily rainfall intensities

2021 ◽  
Author(s):  
Rasmus Benestad
Keyword(s):  
Climate Model ◽  
Hydrological Cycle ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Data Availability ◽  
Time Dimension ◽  
Hourly Rainfall ◽  
Idf Curves ◽  
Rainfall Statistics

<p>Global warming is associated with an increased rate of evaporation due to higher surface temperatures which also implies a higher hydrological cycle turn-around in a steady-state atmosphere with respect to the water budget. The latter is accompanied with increased atmospheric overturning and more convective activity. In addition, there have been indications of a decreasing area of 24-hr rainfall on a global scale over the last decades, suggesting that rainfall is becoming concentrated over smaller regions. There have also been indications of higher cloud tops. In sum, a consequence of an increased greenhouse effect and modified hydrological cycle is an increased probability for heavy rainfall on local scales and a greater risk of flooding. Changes in risks connected to meteorological and hydrological challenges make it necessary to adapt to new weather statistics. For instance, there is a need to estimate the frequency of heavy downpour and their return levels, both for 24-hr amounts and sub-daily timescales. It is common to account for extreme rainfall by designing infrastructure with the help of intensity-duration-frequency (IDF) curves. One problem is that the IDF curves are based on long records of hourly rainfall measurements that are not widely available. Traditional IDF curves have also been fitted assuming stationary statistics, while climate change implies non-stationary weather statistics. We propose a formula for downscaling sub-daily rainfall intensity based on 24-hr rainfall statistics that is not as limited by data availability nor assumes stationarity. This formula provides a crude and approximate and rule-of-thumb for sites with 24-hr rain gauge data and can be used in connection with downscaling of climate model results. It also represents a way of downscaling rainfall statistics in terms of the time dimension.</p>

scholarly journals Temporal change of extreme precipitation intensity–duration–frequency relationships in Thailand

2021 ◽  
Author(s):  
N. Yamoat ◽  
R. Hanchoowong ◽  
S. Sriboonlue ◽  
A. Kangrang
Keyword(s):  
Time Series ◽  
Extreme Precipitation ◽  
Extreme Rainfall ◽  
Precipitation Intensity ◽  
Rainfall Time Series ◽  
The Past ◽  
The North ◽  
Hourly Rainfall ◽  
Idf Curves ◽  
Intensity Duration Frequency

Abstract Due to climate change, many research studies have derived the updated extreme precipitation intensity–duration–frequency relationship (IDF curve) from forecasted sub-hourly rainfall intensity time series, which is one of the most important tools for the planning and designing of hydraulic infrastructures. In this study, the IDF curves (1990–2016) of the six regions and procedures are used in accordance with those of the Royal Irrigation Department (RID)’s study (1950–1988). Each set of IDF relationships consists of 81 intensity values which are the combination of nine durations and nine return periods. The intensity ratios of this study and RID are compared. A greater-than-1 ratio indicates extreme intensity increment from the past to the present. Considering 81 ratios for each region, the number of greater-than-1 ratios for the North, Northeast, Central, East, West, and South regions are 8, 2, 31, 34, 6, and 7, respectively. These ratio numbers are far below 81 which means that the majority of extreme rainfall intensities do not increase from the past to the present. The study found that using accurate historical sub-hourly rainfall time series to create a set of IDF curves would be more reliable than using forecasted rainfall modeling.

scholarly journals Impact of air–sea coupling on the climate change signal over the Iberian Peninsula

2021 ◽  
Author(s):  
Alba de la Vara ◽  
William Cabos ◽  
Dmitry V. Sein ◽  
Claas Teichmann ◽  
Daniela Jacob
Keyword(s):  
Climate Change ◽  
Iberian Peninsula ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Regional Distribution ◽  
Coupled Model ◽  
Climate Change Signal ◽  
The North ◽  
The Mediterranean ◽  
The Impact

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.

scholarly journals Kecenderungan dan Perubahan Hujan Ekstrem Harian di Pulau Madura

2020 ◽  
Vol 18 (1) ◽  
pp. 89-96
Author(s):  
Ahmad Nur Akma Juangga Fura ◽  
Retno Utami Agung Wiyono ◽  
Indarto Indarto
Keyword(s):  
Flood Hazard ◽  
Parametric Method ◽  
Extreme Rainfall ◽  
Kendall Test ◽  
Random Processes ◽  
Rain Gauge ◽  
Rainfall Trend ◽  
Significance Level ◽  
High Level ◽  
Crossing Test

Madura subject to a high level of flood hazard. One of the main causes of flood is extreme rainfall. Global warming generates changes in the amount of extreme rainfall. This research is conducted to identify and to analyze the trends, changes, and randomness of 24-hour extreme rainfall data on Madura Island. The method used is a non-parametric method which includes the Median Crossing test, the Mann-Kendall test, and the Rank-Sum test at the significance level of α =0.05. The analysis was carried out on 31 rain gauge stations. The recording period observed is between 1991-2015. The results of the analysis show that based on the Median Crossing test, most rainfall stations have data originating from random processes. The result shows also that the maximum 24-hour extreme rainfall trend is significantly decreased in a few locations, while for the majority of other stations have no experience a significant trend.

scholarly journals Estimating Rain Rates from Tipping-Bucket Rain Gauge Measurements

2008 ◽  
Vol 25 (1) ◽  
pp. 43-56 ◽  
Author(s):  
Jianxin Wang ◽  
Brad L. Fisher ◽  
David B. Wolff
Keyword(s):  
Rain Rate ◽  
Tropical Rainfall Measuring Mission ◽  
Rain Gauge ◽  
Radar Reflectivity ◽  
Time Shift ◽  
Estimation Errors ◽  
Rate Estimation ◽  
Reflectivity Data ◽  
Rain Rates ◽  
Event Definition

Abstract This paper describes the cubic spline–based operational system for the generation of the Tropical Rainfall Measuring Mission (TRMM) 1-min rain-rate product 2A-56 from tipping-bucket (TB) gauge measurements. A simulated TB gauge from a Joss–Waldvogel disdrometer is employed to evaluate the errors of the TB rain-rate estimation. These errors are very sensitive to the time scale of rain rates. One-minute rain rates suffer substantial errors, especially at low rain rates. When 1-min rain rates are averaged over 4–7-min intervals or longer, the errors dramatically reduce. Estimated lower rain rates are sensitive to the event definition whereas the higher rates are not. The median relative absolute errors are about 22% and 32% for 1-min rain rates higher and lower than 3 mm h−1, respectively. These errors decrease to 5% and 14% when rain rates are used at the 7-min scale. The radar reflectivity–rain-rate distributions drawn from the large amount of 7-min rain rates and radar reflectivity data are mostly insensitive to the event definition. The time shift due to inaccurate clocks can also cause rain-rate estimation errors, which increase with the shifted time length. Finally, some recommendations are proposed for possible improvements of rainfall measurements and rain-rate estimations.

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