scholarly journals Development and Evaluation of Mei-Yu Season Quantitative Precipitation Forecasts in Taiwan River Basins Based on a Conceptual Climatology Model

2012 ◽  
Vol 27 (3) ◽  
pp. 586-607 ◽  
Author(s):  
Chung-Chieh Wang ◽  
Chu-Ying Kung ◽  
Cheng-Shang Lee ◽  
George Tai-Jen Chen
Keyword(s):  
Heavy Rainfall ◽  
Statistical Tests ◽  
River Basins ◽  
Short Wave ◽  
Rain Gauge ◽  
Quantitative Precipitation Forecasts ◽  
Southern Taiwan ◽  
Upper Level ◽  
Central Weather Bureau ◽  
Rainfall Climatology

Abstract Using rain gauge data during 134 mei-yu frontal cases in May–June 1991–2006, a rainfall climatology in relation to the positions of fronts every 0.5° in Taiwan is obtained, showing widespread precipitation with maxima over windward mountain slopes associated with frontal passages. For six major river basins, rainfall characteristics and synoptic factors are further analyzed to build a conceptual climatology model for short-term quantitative precipitation forecasts (QPFs). The four basins in central–southern Taiwan exhibit increased heavy-rainfall frequencies (>25%) roughly from 2° south to 1° north of the front, while the two basins in northern Taiwan have lower frequencies with different characteristics mainly due to the differences in their topography. The synoptic factors in the checklist employed by the Central Weather Bureau and important to heavy rainfall are identified for each of the six basins through statistical tests and their threat score (TS). These factors include those related to mei-yu fronts, low-level jets and moisture, upper-level divergence–diffluence, and short-wave troughs. A conceptual climatology model that uses both synoptic and probability forecasting guidance is developed, and in practice the average rainfall climatology is replaced by one obtained for heavy-rainfall periods if either of the two guidance schemes indicates heavy-rainfall possibility. This model for 0–6- and 0–12-h QPFs is also evaluated for its usefulness using cases during the 2007–08 seasons. With typical TSs of 0.2–0.3 (for heavy rainfall), this approach outperforms simple climatology in all six basins especially toward higher thresholds (about 20–50 mm) and for 12-h events, where it also shows advantages over model QPFs in southern Taiwan. Thus, the model can provide useful information for operational use.

scholarly journals Statistical Characteristic of Heavy Rainfall Associated with Typhoons near Taiwan Based on High-Density Automatic Rain Gauge Data

2016 ◽  
Vol 97 (8) ◽  
pp. 1363-1375 ◽  
Author(s):  
Chun-Chieh Wu ◽  
Tzu-Hsiung Yen ◽  
Yi-Hsuan Huang ◽  
Cheng-Ku Yu ◽  
Shin-Gan Chen
Keyword(s):  
Heavy Rainfall ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Statistical Characteristics ◽  
Rain Gauge Data ◽  
Mountainous Regions ◽  
Rain Gauges ◽  
Weather Stations ◽  
Central Weather Bureau

Abstract This study utilizes data compiled over 21 years (1993–2013) from the Central Weather Bureau of Taiwan to investigate the statistical characteristics of typhoon-induced rainfall for 53 typhoons that have impacted Taiwan. In this work the data are grouped into two datasets: one includes 21 selected conventional weather stations (referred to as Con-ST), and the other contains all the available rain gauges (250–500 gauges, mostly automatic ones; referred to as All-ST). The primary aim of this study is to understand the potential impacts of the different gauge distributions between All-ST and Con-ST on the statistical characteristics of typhoon-induced rainfall. The analyses indicate that although the average rainfall amount calculated with Con-ST is statistically similar to that with All-ST, the former cannot identify the precipitation extremes and rainfall distribution appropriately, especially in mountainous areas. Because very few conventional stations are located over the mountainous regions, the cumulative frequency obtained solely from Con-ST is not representative. As compared to the results from All-ST, the extreme rainfall assessed from Con-ST is, on average, underestimated by 23%–44% for typhoons approaching different portions of Taiwan. The uneven distribution of Con-ST, with only three stations located in the mountains higher than 1000 m, is likely to cause significant biases in the interpretation of rainfall patterns. This study illustrates the importance of the increase in the number of available stations in assessing the long-term rainfall characteristic of typhoon-associated heavy rainfall in Taiwan.

scholarly journals The modification of the typhoon rainfall climatology model in Taiwan

2013 ◽  
Vol 13 (1) ◽  
pp. 65-74 ◽  
Author(s):  
C.-S. Lee ◽  
L.-R. Huang ◽  
D. Y.-C. Chen
Keyword(s):  
False Alarm ◽  
Rain Gauge ◽  
Probability Of Detection ◽  
Typhoon Track ◽  
Independent Case ◽  
Accumulated Rainfall ◽  
Typhoon Rainfall ◽  
Climatological Model ◽  
Central Weather Bureau ◽  
Rainfall Climatology

Abstract. This study is focused on the modification of a typhoon rainfall climatological model, by using the dataset up to 2006 and including data collected from rain gauge stations established after the 921 earthquake (1999). Subsequently, the climatology rainfall models for westward- and northward-moving typhoons are established by using the typhoon track classification from the Central Weather Bureau. These models are also evaluated and examined using dependent cases collected between 1989 and 2006 and independent cases collected from 2007 to 2011. For the dependent cases, the average total rainfall at all rain gauge stations forecasted using the climatology rainfall models for westward- (W-TRCM12) and northward-moving (N-TRCM12) typhoons is superior to that obtained using the original climatological model (TRCM06). Model W-TRCM12 significantly improves the precipitation underestimation of model TRCM06. The independent cases show that model W-TRCM12 provides better accumulated rainfall forecasts and distributions than model TRCM06. A climatological model for accompanied northeastern monsoons (A-TRCM12) for special typhoon types has also been established. The current A-TRCM12 model only contains five historical cases and various typhoon combinations can cause precipitation in different regions. Therefore, precipitation is likely to be significantly overestimated and high false alarm ratios are likely to occur in specific regions. For example, model A-TRCM12 significantly overestimates the rainfall forecast for Typhoon Mitag, an independent case from 2007. However, it has a higher probability of detection than model TRCM06. From a disaster prevention perspective, a high probability of detection is much more important than a high false alarm ratio. The modified models can contribute significantly to operational forecast.

scholarly journals Synoptic environment associated with heavy rainfall events on the coastland of Northeast Brazil

2013 ◽  
Vol 35 ◽  
pp. 73-78 ◽  
Author(s):  
P. T. Oliveira ◽  
K. C. Lima ◽  
C. M. Santos e Silva
Keyword(s):  
Coastal Area ◽  
Heavy Rainfall ◽  
Daily Rainfall ◽  
South Atlantic Convergence Zone ◽  
Rain Gauge ◽  
Economic Losses ◽  
Heavy Rainfall Event ◽  
Northeast Brazil ◽  
Daily Data ◽  
Upper Level

Abstract. Northeast Brazil (NEB) has an extensive coastal area, often hit by natural disasters that bring many social and economic losses. The objective of this work was to study the synoptic environment associated with a heavy rainfall event (HRE) on the coastland of NEB. We used daily rainfall data for coastal area of NEB between the states of Rio Grande do Norte and Bahia, divided into two subregions: north and south coastland. This data was obtained from the hydrometeorological network managed by the Agência Nacional de Águas and the daily data reanalysis from the ERAInterim. For the selection of HRE the technique of quantiles was used, thus defined HRE where at least one rain gauge recorded rainfall above 95th percentile. The interannual distribution of events showed occurrence maximum in La Niña years and minimal in El Niño years. The results suggest that the HRE were formed mainly due to the action of upper-level cyclonic vortex, in hight levels, and due to the action to South Atlantic convergence zone, in low levels.

Possible Earth‐Tide Modulations of Early Aftershocks in Southern Taiwan

2019 ◽  
Vol 109 (4) ◽  
pp. 1571-1577 ◽  
Author(s):  
Chi‐Chia Tang ◽  
Li‐Chin Lin ◽  
Yinhe Luo ◽  
Shujun Liu ◽  
Rui Xu ◽  
...  
Keyword(s):  
Matched Filter ◽  
Statistical Tests ◽  
Earth Tide ◽  
Minor Role ◽  
Source Regions ◽  
Tidal Stress ◽  
Stress Changes ◽  
Southern Taiwan ◽  
Earthquake Generation ◽  
Central Weather Bureau

Abstract Earth‐tide stresses often have been considered to be incapable of directly triggering large earthquakes, but they do play a role in earthquake modulation. Despite its relatively minor role, tidal stress analysis is valuable for understanding earthquake generation. In this study, we used the matched‐filter technique to detect approximately three times more early aftershocks (EAs) following the 2010 ML 6.4 Jiashian and 2012 ML 6.4 Wutai mainshocks than are listed in the Central Weather Bureau catalog in southern Taiwan. We examined the influence of tidal stresses on the occurrence of EAs and identified that small EAs frequently occurred near or at negative Coulomb and shear stress changes induced by Earth tide. Statistical tests indicated a very low likelihood for the EAs to be randomly distributed across a single day. It is likely that Earth‐tide stresses can modulate these small EA occurrences. We proposed that tidal stresses can affect fluid diffusion and pore pressure of crustal cracks around the mainshock source regions when the regions are under a critically stressed circumstance. Our results were inconclusive regarding a causal relationship between tidal stresses and EA occurrences in the first few hours after the mainshocks.

Probabilistic Quantitative Precipitation Forecasts for River Basins

1993 ◽  
Vol 8 (4) ◽  
pp. 424-439 ◽  
Author(s):  
Roman Krzysztofowicz ◽  
William J. Drzal ◽  
Theresa Rossi Drake ◽  
James C. Weyman ◽  
Louis A. Giordano
Keyword(s):  
River Basins ◽  
Quantitative Precipitation Forecasts

scholarly journals Assessing Prone Areas to Heavy Rainfall and the Impaction of the Upper Warm Temperature Anomaly during March–May Rainfall Season in Tanzania

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Kantamla Biseke Mafuru ◽  
Tan Guirong
Keyword(s):  
Heavy Rainfall ◽  
Temperature Anomaly ◽  
Temporal Distribution ◽  
Warning System ◽  
Congo Basin ◽  
Horizontal Wind ◽  
Warm Temperature ◽  
Rainfall Season ◽  
Key Factor ◽  
Upper Level

This study analyses the spatial and temporal distribution of heavy rainfall events (HREs) and its associated circulation anomalies over Tanzania during March to May (MAM) rainfall season of 1980–2010. A total of 822 HREs were revealed, concentrated over the northern sector (NS) of the country. Years with anomalous HREs are associated with low-level westerly convergence, advection of moisture from both the Indian Ocean and Congo basin, an upper warm temperature anomaly (UWTA), intensified and well-positioned Intertropical Convergence Zone (ITCZ), and pronounced rising motion since the ascending limb of the Walker type of circulation is centered over Tanzania. The analysis of the UWTA in this study has brought a key factor in exploring the possible likely cause and improved early warning system for the HREs during the MAM rainfall season in Tanzania. Making use of the thermal wind equation and the velocity divergent form of the continuity equation (DFCE), we found that the UWTA results into an upper-level horizontal wind divergence which significantly accelerates vertical ascent, deepening the surface low pressure for an enhanced convective process and HREs formation.

scholarly journals A Comparison Between Global Satellite Mapping of Precipitation Data and High-Resolution Radar Data – A Case Study of Localized Torrential Rainfall over Japan

2021 ◽  
Vol 16 (4) ◽  
pp. 786-793
Author(s):  
Yoshiaki Hayashi ◽  
Taichi Tebakari ◽  
Akihiro Hashimoto ◽  
◽  
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Daily Rainfall ◽  
Radar Data ◽  
Rain Gauge ◽  
Hourly Rainfall ◽  
The Difference ◽  
Microwave Imager ◽  
Satellite Mapping

This paper presents a case study comparing the latest algorithm version of Global Satellite Mapping of Precipitation (GSMaP) data with C-band and X-band Multi-Parameter (MP) radar as high-resolution rainfall data in terms of localized heavy rainfall events. The study also obliged us to clarify the spatial and temporal resolution of GSMaP data using high-accuracy ground-based radar, and evaluate the performance and reporting frequency of GSMaP satellites. The GSMaP_Gauge_RNL data with less than 70 mm/day of daily rainfall was similar to the data of both radars, but the GSMaP_Gauge_RNL data with over 70 mm/day of daily rainfall was not, and the calibration by rain-gauge data was poor. Furthermore, both direct/indirect observations by the Global Precipitation Measurement/Microwave Imager (GPM/GMI) and the frequency thereof (once or twice) significantly affected the difference between GPM/GMI data and C-band radar data when the daily rainfall was less than 70 mm/day and the hourly rainfall was less than 20 mm/h. Therefore, it is difficult for GSMaP_Gauge to accurately estimate localized heavy rainfall with high-density particle precipitation.

scholarly journals Mesoscale Convective Systems: A Case Scenario of the ‘Heavy Rainfall’ Event of 15–20 January 2013 over Southern Africa

Climate ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 73
Author(s):  
Modise Wiston ◽  
Kgakgamatso Marvel Mphale
Keyword(s):  
Atlantic Ocean ◽  
Southern Africa ◽  
Heavy Rainfall ◽  
Rainfall Event ◽  
Mesoscale Convective Systems ◽  
Heavy Rainfall Event ◽  
Convergence Zone ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Upper Level

Southern east Africa is prone to some extreme weather events and interannual variability of the hydrological cycle, including tropical cyclones and heavy rainfall events. Most of these events occur during austral summer and are linked to shifts in the intertropical convergence zone, changes in El Niño Southern Oscillation signatures, sea surface temperature and sea level pressure. A typical example include mesoscale convective systems (MCSs) that occur between October and March along the eastern part, adjacent to the warm waters of Mozambique Channel and Agulhas Current. In this study we discuss a heavy rainfall event over southern Africa, focusing particularly on the period 15–20 January 2013, the period during which MCSs were significant over the subcontinent. This event recorded one of the historic rainfalls due to extreme flooding and overflows, loss of lives and destruction of economic and social infrastructure. An active South Indian Convergence Zone was associated with the rainfall event sustained by a low-level trough linked to a Southern Hemisphere planetary wave pattern and an upper-level ridge over land. In addition, also noteworthy is a seemingly strong connection to the strength of the African Easterly Jet stream. Using rainfall data, satellite imagery and re-analysis (model processed data combined with observations) data, our analysis indicates that there was a substantial relation between rainfall totals recorded/observed and the presence of MCSs. The low-level trough and upper-level ridge contributed to moisture convergence, particularly from tropical South East Atlantic Ocean, which in turn contributed to the prolonged life span of the rainfall event. Positive temperature anomalies favored the substantial contribution of moisture fluxes from the Atlantic Ocean. This study provides a contextual assessment of rainfall processes and insight into the physical control mechanisms and feedback of large-scale convective interactions over tropical southern Africa.

scholarly journals Mesoscale and Local Scale Evaluations of Quantitative Precipitation Estimates by Weather Radar Products during a Heavy Rainfall Event

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Basile Pauthier ◽  
Benjamin Bois ◽  
Thierry Castel ◽  
D. Thévenin ◽  
Carmela Chateau Smith ◽  
...  
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Rain Gauge ◽  
Local Scale ◽  
Rainfall Event ◽  
Heavy Rainfall Event ◽  
Preliminary Evaluation ◽  
Rainfall Variation ◽  
Hourly Rainfall ◽  
Rain Gauge Network

A 24-hour heavy rainfall event occurred in northeastern France from November 3 to 4, 2014. The accuracy of the quantitative precipitation estimation (QPE) by PANTHERE and ANTILOPE radar-based gridded products during this particular event, is examined at both mesoscale and local scale, in comparison with two reference rain-gauge networks. Mesoscale accuracy was assessed for the total rainfall accumulated during the 24-hour event, using the Météo France operational rain-gauge network. Local scale accuracy was assessed for both total event rainfall and hourly rainfall accumulations, using the recently developed HydraVitis high-resolution rain gauge network Evaluation shows that (1) PANTHERE radar-based QPE underestimates rainfall fields at mesoscale and local scale; (2) both PANTHERE and ANTILOPE successfully reproduced the spatial variability of rainfall at local scale; (3) PANTHERE underestimates can be significantly improved at local scale by merging these data with rain gauge data interpolation (i.e., ANTILOPE). This study provides a preliminary evaluation of radar-based QPE at local scale, suggesting that merged products are invaluable for applications at very high resolution. The results obtained underline the importance of using high-density rain-gauge networks to obtain information at high spatial and temporal resolution, for better understanding of local rainfall variation, to calibrate remotely sensed rainfall products.

A 33-yr Mei-Yu-Season Climatology of Shear Lines over the Yangtze–Huai River Basin in Eastern China

2020 ◽  
Vol 59 (6) ◽  
pp. 1125-1137
Author(s):  
Xiuping Yao ◽  
Jiali Ma ◽  
Da-Lin Zhang ◽  
Lizhu Yan
Keyword(s):  
River Basin ◽  
Heavy Rainfall ◽  
Eastern China ◽  
Rain Gauge ◽  
Reanalysis Data ◽  
Central Basin ◽  
The South ◽  
South Central ◽  
Huai River Basin ◽  
Huai River

AbstractA 33-yr climatology of shear lines occurring over the Yangtze–Huai River basin (YHSLs) of eastern China during the mei-yu season (i.e., June and July) of 1981–2013 is examined using the daily ERA-Interim reanalysis data and daily rain gauge observations. Results show that (i) nearly 75% of the heavy-rainfall days (i.e., >50 mm day−1) are accompanied by YHSLs, (ii) about 66% of YHSLs can produce heavy rainfall over the Yangtze–Huai River basin, and (iii) YHSL-related heavy rainfall occurs frequently in the south-central basin. The statistical properties of YHSLs are investigated by classifying them into warm, cold, quasi-stationary, and vortex types based on their distinct flow and thermal patterns as well as orientations and movements. Although the warm-type rainfall intensity is the weakest among the four, it has the highest number of heavy-rainfall days, making it the largest contributor (33%) to the total mei-yu rainfall amounts associated with YHSLs. By comparison, the quasi-stationary type has the smallest number of heavy-rainfall days, contributing about 19% to the total rainfall, whereas the vortex type is the more frequent extreme-rain producer (i.e., >100 mm day−1). The four types of YHSLs are closely related to various synoptic-scale low-to-midtropospheric disturbances—such as the southwest vortex, low-level jets, and midlatitude traveling perturbations that interact with mei-yu fronts over the basin and a subtropical high to the south—that provide favorable lifting and the needed moisture supply for heavy-rainfall production. The results have important implications for the operational rainfall forecasts associated with YHSLs through analog pattern recognition.

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