Enhancement of Afternoon Thunderstorm Activity by Urbanization in a Valley: Taipei

2007 ◽  
Vol 46 (9) ◽  
pp. 1324-1340 ◽  
Author(s):  
Tsing-Chang Chen ◽  
Shih-Yu Wang ◽  
Ming-Cheng Yen
Keyword(s):  
Summer Rainfall ◽  
Southwest Monsoon ◽  
Thunderstorm Activity ◽  
Ground Subsidence ◽  
Maximum Rainfall ◽  
Taipei Basin ◽  
Downwind Side ◽  
River Valleys ◽  
The City ◽  
Northern Taiwan

Abstract Located in northern Taiwan, Taipei is a metropolis surrounded by hills and mountains that form a basin in which two river valleys funnel the surface airflow of this basin to the open sea. Because of the southwest monsoon, summer is a dry season in northern Taiwan but is the season of maximum rainfall in the Taipei basin. This unusual summer rainfall maximum in Taipei is largely produced by afternoon/evening thunderstorms—in particular, on the downwind side and slopes of mountains south of the city. The population in the city of Taipei and the county in which this city is located has more than tripled during the past four decades while land use for building and surface construction increased by a factor of 3. This urbanization may contribute to an increase of 1.5°C in daily mean temperature, a decrease of 1°C in daily temperature range, an increase of more than 67% in the frequency of afternoon/evening thunderstorms, and an increase of 77% in rainfall generated by thunderstorms. These findings may explain the reduction in the water supply deficit to the Taipei metropolitan area and the ground subsidence of the Taipei basin caused by the excessive use of groundwater. Results of this study also provide important information for urban planning and pollution control and for management of the increasing traffic hazards caused by the enhanced thunderstorm activity and rainfall.

scholarly journals Interannual Variation of Summer Rainfall in the Taipei Basin

2016 ◽  
Vol 55 (8) ◽  
pp. 1789-1812 ◽  
Author(s):  
Tsing-Chang Chen ◽  
Jenq-Dar Tsay ◽  
Eugene S. Takle
Keyword(s):  
Southern Oscillation ◽  
Summer Rainfall ◽  
Thunderstorm Activity ◽  
River Valley ◽  
Interannual Variations ◽  
Asian Monsoon Region ◽  
Maximum Rainfall ◽  
Vapor Flux ◽  
Taipei Basin ◽  
Northern Taiwan

AbstractThe Taipei basin, located in northern Taiwan, is formed at the intersection of the Tanshui River valley (~30 km) and the Keelung River valley (~60 km). Summer is the dry season in northern Taiwan, but the maximum rainfall in the Taipei basin occurs during 15 June–31 August. The majority of summer rainfall in this basin is produced by afternoon thunderstorms. Thus, the water supply, air/land traffic, and pollution for this basin can be profoundly affected by interannual variations of thunderstorm days and rainfall. Because the mechanism for these interannual variations is still unknown, a systematic analysis is made of thunderstorm days and rainfall for the past two decades (1993–2013). These two variables are found to correlate opposite interannual variations of sea surface temperature anomalies over the National Oceanic and Atmospheric Administration Niño-3.4 region. Occurrence days for afternoon thunderstorms and rainfall amounts in the Taipei basin double during the cold El Niño–Southern Oscillation (ENSO) phase relative to the warm phase. During the latter phase, a stronger cold/drier monsoon southwesterly flow caused by the Pacific–Japan Oscillation weakens the thunderstorm activity in the Taipei basin through the land–sea breeze. In contrast, the opposite condition occurs during the cold ENSO phase. The water vapor flux over the East/Southeast Asian monsoon region converges more toward Taiwan to maintain rainfall over the Taipei basin during the cold ENSO phase than during the warm ENSO phase.

scholarly journals A Forecast Advisory for Afternoon Thunderstorm Occurrence in the Taipei Basin during Summer Developed from Diagnostic Analysis*

2016 ◽  
Vol 31 (2) ◽  
pp. 531-552 ◽  
Author(s):  
Tsing-Chang Chen ◽  
Jenq-Dar Tsay ◽  
Eugene S. Takle
Keyword(s):  
Onset Time ◽  
Sea Breeze ◽  
Forecast Model ◽  
Well Being ◽  
Thunderstorm Activity ◽  
Meteorological Conditions ◽  
Diurnal Variations ◽  
Maximum Rainfall ◽  
Taipei Basin ◽  
Synoptic Conditions

Abstract Summer is a dry season in northern Taiwan. By contrast, the Taipei basin, located in this region, has its maximum rainfall during summer (15 June–31 August), when 78% of this rainfall is contributed by afternoon thunderstorms. This thunderstorm activity occurs during only 20 days in summer. Because of the pronounced impacts on the well-being of three million people in the basin and the relative infrequency of occurrence, forecasting thunderstorm events is an important operational issue in the Taipei basin. The basin’s small size (30 km × 60 km), with two river exits and limited thunderstorm occurrence days, makes the development of a thunderstorm activity forecast model for this basin a great challenge. Synoptic analysis reveals a thunderstorm day may develop from morning synoptic conditions free of clouds/rain, with a NW–SE-oriented dipole located south of Taiwan and southwesterlies straddling the low and high of this dipole. The surface meteorological conditions along the two river valleys exhibit distinct diurnal variations of pressure, temperature, dewpoint depression, relative humidity, and land–sea breezes. The primary features of the synoptic conditions and timings of the diurnal cycles for the four surface variables are utilized to develop a two-step hybrid forecast advisory for thunderstorm occurrence. Step 1 validates the 24-h forecasts for the 0000 UTC (0800 LST) synoptic conditions and timings for diurnal variations for the first five surface variables on thunderstorm days. Step 2 validates the same synoptic and surface meteorological conditions (including sea-breeze onset time) observed on the thunderstorm day. The feasibility of the proposed forecast advisory is successfully demonstrated by these validations.

Analysis and Simulations of a Heavy Rainfall Event Associated with the Passage of a Shallow Front over Northern Taiwan on 2 June 2017

2021 ◽  
Keyword(s):  
Heavy Rainfall ◽  
Heavy Rainfall Event ◽  
Mountain Range ◽  
Cold Air ◽  
Taipei Basin ◽  
Resolution Model ◽  
Northern Side ◽  
High Resolution Model ◽  
River Valleys ◽  
Northern Taiwan

Abstract From 0200 to 1000 LST 2 June 2017, the shallow, East-West oriented Mei-Yu front (< 1 km) cannot move over the Yang-Ming Mountains (with peaks ∼ 1120 m) when it first arrives. The postfrontal cold air at the surface is deflected by the Yang-Ming Mountains and moves through the Keelung River and Tamsui River valleys into the Taipei Basin. The shallow northerly winds are anchored along the northern side of the Yang-Ming Mountains for 8 hours. In addition, the southwesterly barrier jet with maximum winds in the 900–950-hPa layer brings in abundant moisture and converges with the northwesterly flow in the southwestern flank of the Mei-Yu frontal cyclone. Therefore, torrential rain (> 600 mm) occurs over the northern side of the Yang-Ming Mountains. From 1100 to 1200 LST, with the gradual deepening of the postfrontal cold air, the front finally passes over the Yang-Ming Mountains and arrives at the Taipei Basin, which results in an E-W oriented rainband with the rainfall maxima over the northwestern coast and Taipei Basin. From 1300 to 1400 LST, the frontal rainband continues to move southward with rainfall over the northwestern slopes of the Snow Mountains. In the prefrontal southwesterly flow, the orographic lifting of the moisture-laden low-level winds results in heavy rainfall on the southwestern slopes of the Snow Mountains and the Central Mountain Range. With the terrain of the Yang-Ming Mountains removed in the high-resolution model, the Mei-Yu front moves quickly southward without a rainfall maximum over the northern tip of Taiwan.

scholarly journals Analysis of the Behavior of Abstractions in Two Urban Micro-Basins of the City of Cuenca (Ecuador), through an Aggregate Model

2021 ◽  
Vol 13 (6) ◽  
pp. 3209
Author(s):  
Ricardo Rubio-Ramírez ◽  
Rubén Jerves-Cobo ◽  
Diego Mora-Serrano
Keyword(s):  
Stormwater Runoff ◽  
Great Sensitivity ◽  
Aggregate Model ◽  
Antecedent Soil Moisture ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Impervious Area ◽  
Process Of Urbanization ◽  
Negative Impacts ◽  
The City

Several cities in developing countries are challenging the permanent process of urbanization. This generates a great disturbance on the hydrological response of the urbanized area during rainfall events, which can cause floods. Among the disturbances that urbanized basins may suffer, it is found that variations in rain losses (hydrological abstractions) can be estimated by the named volumetric runoff coefficient (CVOL) methodology. In the present study, this methodology is used in an attempt to estimate the hydrological abstraction of two nearby urbanized basins, with different degrees of impermeability, located in the city of Cuenca in Ecuador. The data for that analysis were collected between April and May of 2017. The results obtained indicate that the micro-basin with the largest impervious area presents the higher initial hydrological losses, the higher rate of decrease in abstractions, and the higher stormwater runoff flows per unit area. In addition, the abstractions found in the two urban micro-basins show great sensitivity to the maximum rainfall intensity and do not relate to the antecedent soil moisture. These results demonstrate the importance of having higher pervious surfaces in urbanized areas because they lead to reduce negative impacts associated with increased stormwater runoff on impervious surfaces.

scholarly journals Quantifying Horizontal and Vertical Movements in Ho Chi Minh City by Sentinel-1 Radar Interferometry

2020 ◽  
Author(s):  
Dinh Ho Tong Minh ◽  
Yen-Nhi NGO ◽  
Thu Trang Lê ◽  
Trung Chon Le ◽  
Hong Son Bui ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
European Space Agency ◽  
Ground Subsidence ◽  
Ho Chi Minh City ◽  
Vertical Movements ◽  
Space Agency ◽  
Permanent Scatterers ◽  
The City ◽  
East West

Ho Chi Minh City (HCMC), the most populous city and the economic center of Viet Nam, has faced ground subsidence in recent decades. This work aims at providing an unprecedented spatial extent coverage of the subsidence in HCMC in both horizontal and vertical components using Interferometric Synthetic Aperture Radar (InSAR) time series. For this purpose, an advanced InSAR technique PSDS (Permanent Scatterers and Distributed Scatterers) was applied to two big European Space Agency (ESA) Sentinel-1 datasets composed of 96 ascending and 202 descending images, acquired from 2014 to 2020 over HCMC area. A time series of 33 Cosmos SkyMED images was also used for comparison purpose. The combination of ascending and descending satellite passes allows the decomposition of the light of sight velocities into horizontal East-west and vertical components. By taking into account the presence of the horizontal East-west movement, our finding indicates that the precision of the decomposed vertical velocity can be improved up to 3 mm/year for Sentinel-1 data. The obtained results revealed that subsidence is most severe in areas along the Sai Gon river in the northwest-southeast axis and the southwest of the city with the maximum value up to 80 mm/year, consistent with findings in the literature. The magnitude of horizontal East-West velocities is relatively small and a large-scale westward motion can be observed in the northwest of the city at a rate of 2-5 mm/year. Together, these results reinforced the remarkable suitability of ESA's Sentinel-1 SAR for subsidence applications even for non-Europe countries such as Vietnam and Southeast Asia.

scholarly journals Persistent Scatterer Interferometry of Sentinel-1 time series to detect ground subsidence in the city of Recife, Brazil

2020 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Enton Bedini
Keyword(s):  
Time Series ◽  
Ground Subsidence ◽  
Persistent Scatterer Interferometry ◽  
Persistent Scatterer ◽  
Radar Imagery ◽  
Long Time ◽  
Satellite Radar ◽  
Surrounding Areas ◽  
Satellite Radar Imagery ◽  
The City

Persistent Scatterer Interferometry (PSI) analysis of Sentinel-1 time series was carried out to detect ground subsidence in the city of Recife, Brazil. The dataset consisted of sixty-eight Sentinel-1A Interferometric Wide (IW) Single Look Complex (SLC) images of the time period April 2017 – September 2019. The images were acquired in descending orbit in VV (vertical transmitting, vertical receiving) polarization. The results of the PSI analysis show that in the city of Recife occur several ground subsidence areas. The largest ground subsidence area occurs between the neighborhoods of Afogados, Torrŏes and Cordeiro. The subsidence rates in this area range from few mm/year up to -15 mm/year. This ground subsidence could be a result of groundwater extraction or of subsidence processes in urbanized reclaimed lands. Similar but smaller ground subsidence areas occur in several localities in Recife. In some cases, subsidence with rates of up to -25 mm/year is noted in small zones where new buildings have been constructed in the last decade. This should be due to ground settlement processes, taking a long time due to the particular soils and geology of the locality. This study can serve as a first contribution for further research on the ground subsidence hazard in the city of Recife and the surrounding areas by means of satellite radar imagery.

Impacts of Urban Processes and Urbanization on Summer Precipitation: A Case Study of Heavy Rainfall in Beijing on 1 August 2006

2011 ◽  
Vol 50 (4) ◽  
pp. 806-825 ◽  
Author(s):  
Shiguang Miao ◽  
Fei Chen ◽  
Qingchun Li ◽  
Shuiyong Fan
Keyword(s):  
Urban Area ◽  
Heavy Rainfall ◽  
Precipitation Amount ◽  
Single Layer ◽  
Urban Land Use ◽  
Squall Line ◽  
Beijing City ◽  
Maximum Rainfall ◽  
Simulated Precipitation ◽  
The City

AbstractFinescale simulations (with 500-m grid spacing) using the Weather Research and Forecasting Model (WRF) were used to investigate impacts of urban processes and urbanization on a localized, summer, heavy rainfall in Beijing. Evaluation using radar and gauge data shows that this configuration of WRF with three-dimensional variational data assimilation of local weather and GPS precipitable water data can simulate this event generally well. Additional WRF simulations were conducted to test the sensitivity of simulation of this storm to different urban processes and urban land-use scenarios. The results confirm that the city does play an important role in determining storm movement and rainfall amount. Comparison of cases with and without the presence of the city of Beijing with respect to the approaching storm shows that the urban effect seems to lead to the breaking of the squall line into convective cells over the urban area. The change of precipitation amount depends on the degree of urbanization (i.e., the change over time in the extent of Beijing city). Model results show that an early urbanization prior to 1980 decreases the maximum rainfall, whereas further urbanization in Beijing is conducive to bifurcating the path of rainfall. According to sensitivity results with a single-layer urban canopy model, the thermal transport (sensible and latent heating) induced by the presence of an urban area apparently is more important than associated momentum transport, with latent and sensible heating apparently having equally important roles in the modification of simulated precipitation. Urban surfaces tend to cause the rainfall to be more locally concentrated. High-rise urban cores may bifurcate the path of rainfall as well as increase the area percentage of heavy rainfall.

scholarly journals Potential Inundation Hazards in the Taipei Basin Induced by Reactivation of the Shanchiao Fault in Northern Taiwan

2010 ◽  
Vol 21 (3) ◽  
pp. 529 ◽  
Author(s):  
Jihn-Sung Lai ◽  
Chun-Ying Chiu ◽  
Hsiang-Kuan Chang ◽  
Jyr-Ching Hu ◽  
Yih-Chi Tan
Keyword(s):  
Taipei Basin ◽  
Northern Taiwan

scholarly journals Study of rainfall features over Goa state during southwest monsoon season

MAUSAM ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 155-162
Author(s):  
S. M. METRI ◽  
KHUSHVIR SINGH
Keyword(s):  
Heavy Rainfall ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
Annual Rainfall ◽  
Statistical Parameters ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Average Rainfall ◽  
Southwest Monsoon Season ◽  
Heavy Rainfall Events

In this paper the rainfall features at different raingauge stations of Goa state have been studied for the period of 30 years. The statistical parameters such as mean monthly rainfall, Standard Deviation and Coefficient of Variation have been computed for each raingauge station of Goa. Some heavy rainfall events during the period have also been studied. The study shows the significant rising trend of rainfall towards the eastern parts of Goa. Goa experiences an average rainfall of about 330 cm annually and around 90% of annual rainfall occurs during southwest monsoon season i.e. (June to September). Studies revealed that most of heavy rainfall events caused due to active off-shore trough and low pressure systems formed over southeast Arabian Sea. It has also come out from the study that the orography of Goa plays an important role in rainfall distribution. Valpoi receives maximum rainfall due to its orographic effect.

scholarly journals ANALISIS SPASIAL TINGKAT BAHAYA LONGSOR KOTA PADANG PANJANG SUMATERA BARAT

2019 ◽  
Vol 5 (3) ◽  
pp. 44-49
Author(s):  
Erna Juita, S.Pd. M.Si ◽  
Dasrizal Dasrizal ◽  
Elvi Zuriyani
Keyword(s):  
Field Research ◽  
Landslide Hazard ◽  
Survey Method ◽  
Scoring Method ◽  
Low Level ◽  
Landslide Hazards ◽  
Score Analysis ◽  
Medium Level ◽  
River Valleys ◽  
The City

Penelitian ini adalah penelitian deskriptif dengan metode survey, Metode yang digunakan dalam tahap analisis tabuler adalah metode scoring berdasarkan hasil penelitian lapangan yang telah dilakukan. Setiap parameter penentu tingkat bahaya longsor diberi skor tertentu. Setiap unit analisis skor tersebut dijumlahkan dan hasil penjumlahan skor selanjutnya diklasifikasikan untuk menentukan tingkat bahaya longsor. wilayah Kota Padang Panjang terbagi atas 3 potensi rawan longsor yaitu: (1) Tingkat sedang, (2) Tingkat rendah dan (2) Tidak rawan. Bahaya Longsor tingkat sedang terdapat di sebagian Kelurahan Bukit Surungan, Pasar Usang, Koto Katik, Koto Panjang, Ganting, dan Sigando, dan Silaing Bawah. Pada Zona ini dapat terjadi longsor jika curah hujan di atas normal, terutama pada daerah yang berbatasan dengan lembah sungai, gawir, tebing jalan atau jika lereng mengalami gangguan. Untuk bahaya longsor tingkat rendah yaitu terdapat di hampir sebagian besar wilayah Kota Padang panjang, bisa dikatakan hampir 2/3 bagian Kota Padang Panjang digolongkan pada kawasan dengan tingkat bahaya longsor rendah. Dan untuk kawasan yang tidak rawan longsor terdapat di sebagian Kelurahan Ganting, Silaing Bawah, Silaing Atas, Kampung Manggis, dan Bukit Surungan. This research is a descriptive research with survey method, the method used in the tabular analysis stage is the scoring method based on the results of field research that has been done. Each parameter determining the level of landslide hazard is given a certain score. Each unit of score analysis is summed and the sum of the results of the next score are classified to determine the level of landslide hazard. The area of Padang Panjang City is divided into 3 potential landslide hazards, namely: (1) Medium level, (2) Low level and (2) Not vulnerable. Medium level landslide hazards are found in parts of Bukit Surungan, Pasar Usang, Koto Katik, Koto Panjang, Ganting, and Sigando, and Silaing Bawah. In this zone landslides can occur if the rainfall is above normal, especially in areas bordering river valleys, swamps, road cliffs or if the slopes experience interference. For low level landslide hazards, which are found in most parts of the city of Padang Panjang, it can be said that almost 2/3 of the city of Padang Panjang is classified as an area with a low level of landslide. And for areas that are not prone to landslides, there are some in Ganting, Silaing Bawah, Silaing Atas, Manggis, and Bukit Surungan.

Sign in / Sign up

Export Citation Format

Share Document