Investigation of a heavy rainfall event over southwestern Taiwan associated with a subsynoptic cyclone during the 2003 Mei-Yu season

Chen, Ching-Sen; Lin, Yuh-Lang; Peng, Wen-Chun; Liu, Che-Ling

doi:10.1016/j.atmosres.2009.10.003

Cited by 33 publications

(17 citation statements)

References 18 publications

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“…WRF has been used in various research applications dealing with convective systems and initiation (Done et al 2004;Schumacher and Johnson 2005;Trier et al 2006;Clark et al 2007;Fitzpatrick et al 2008) as well as precipitation distribution and prediction (Miller and Weisman 2002;Kusaka et al 2005). Research applications using WRF to simulate heavy precipitation related to flooding have also been conducted in various regions around the world, including Taiwan (Chen et al 2010) and Texas (Lowrey and Yang 2008). In addition, modeling studies have been carried out in various locations to examine the sensitivity of mesoscale circulations to surface characteristics (Mahfouf et al 1987;Boyles et al 2007;Hong et al 1995).…”

Section: Methodsmentioning

confidence: 97%

Analysis of a Warm-Season Surface-Influenced Mesoscale Convective Boundary in Northwest Mississippi

Dyer

2011

Journal of Hydrometeorology

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The lower Mississippi River alluvial valley in southeastern Arkansas, northeastern Louisiana, and northwestern Mississippi is characterized by widespread agriculture with few urban areas. Land use is predominantly cultivated cropland with minimal topographic variation; the eastern edge of the alluvial valley is defined by a rapid, although small, change in elevation into a heavily forested landscape, however. This change in land use/land cover has been shown to potentially enhance precipitation through generation of a weak mesoscale convective boundary. This project defines the influence of the land surface on associated precipitation processes by simulating a convective rainfall event that was influenced by regional surface features. Analysis was conducted using a high-resolution simulated dataset generated by the Weather Research and Forecasting Model (WRF). Results show that the strongest uplift coincides with an abrupt lowlevel thermal boundary, developed primarily by a rapid change from sensible to latent heat flux relative to the agricultural and forested areas, respectively. In addition, surface heating over the cultivated landscape appears to destabilize the boundary layer, with precipitation occurring as air is advected across the land cover boundary and the associated thermal gradient. This information can be used to define and predict surfaceinfluenced convective precipitation along agricultural boundaries in other regions where the synoptic environment is weak.

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Section: Methodsmentioning

confidence: 97%

Analysis of a Warm-Season Surface-Influenced Mesoscale Convective Boundary in Northwest Mississippi

Dyer

2011

Journal of Hydrometeorology

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“…In the sensitivity experiments, topography was modified only in D3 domain according to the methodology of Miao et al (2003) and Koletsis et al (2009Koletsis et al ( , 2010. Chiao et al (2004) and Chen et al (2010Chen et al ( , 2011Chen et al ( , 2013) followed a similar procedure in their numerical experiments on the role of orography, with no modifications at the topography of their external grid. Figure 1 illustrates the actual topography of Greece and the three nested domains.…”

Section: Data Sources and Model Setupmentioning

confidence: 99%

Numerical modeling and analysis of the effect of complex Greek topography on tornadogenesis

Matsangouras

Pytharoulis

2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Tornadoes have been reported in Greece over recent decades in specific sub-geographical areas and have been associated with strong synoptic forcing. While it has been established that meteorological conditions over Greece are affected at various scales by the significant variability of topography, the Ionian Sea to the west and the Aegean Sea to the east, there is still uncertainty regarding topography's importance on tornadic generation and development.The aim of this study is to investigate the role of topography in significant tornadogenesis events that were triggered under strong synoptic scale forcing over Greece. Three tornado events that occurred over the last years in Thebes (Boeotia, 17 November 2007), Vrastema (Chalkidiki, 12 February 2010) and Vlychos (Lefkada, 20 September 2011) were selected for numerical experiments. These events were associated with synoptic scale forcing, while their intensities were T4-T5 (on the TORRO scale), causing significant damage. The simulations were performed using the non-hydrostatic weather research and forecasting model (WRF), initialized by European Centre for Medium-Range Weather Forecasts (ECMWF) gridded analyses, with telescoping nested grids that allow for the representation of atmospheric circulations ranging from the synoptic scale down to the mesoscale. In the experiments, the topography of the inner grid was modified by: (a) 0 % (actual topography) and (b) −100 % (without topography), making an effort to determine whether the occurrence of tornadoes -mainly identified by various severe weather instability indices -could be indicated by modifying topography. The principal instability variables employed consisted of the bulk Richardson number (BRN) shear, the energy helicity index (EHI), the storm-relative environmental helicity (SRH), and the maximum convective available potential energy (MCAPE, for parcels with maximum θ e ). Additionally, a model verification was conducted for every sensitivity experiment accompanied by analysis of the absolute vorticity budget.Numerical simulations revealed that the complex topography constituted an important factor during the

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“…Recent studies have shown that the WRF model has good potential in handling some rainfall features, e.g. the rainfall timing, location and evolution; however in producing the accurate rainfall quantities, the results are still not ideal (Chang et al, 2009;Hong and Lee, 2009;Shem and Shepherd, 2009;Chen et al, 2010;Liu et al, 2012a). As for data assimilation, the three/four-dimensional variational methods (3D-Var/4D-Var), ensemble Kalman filter (EnKF) and latent heating nudging (LHN) are among the most effective assimilation techniques that are commonly applied to radar data .…”

Section: J Liu Et Almentioning

confidence: 99%

A study on WRF radar data assimilation for hydrological rainfall prediction

Liu

Bray

Han

2013

Hydrol. Earth Syst. Sci.

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Abstract. Mesoscale numerical weather prediction (NWP) models are gaining more attention in providing highresolution rainfall forecasts at the catchment scale for realtime flood forecasting. The model accuracy is however negatively affected by the "spin-up" effect and errors in the initial and lateral boundary conditions. Synoptic studies in the meteorological area have shown that the assimilation of operational observations, especially the weather radar data, can improve the reliability of the rainfall forecasts from the NWP models. This study aims at investigating the potential of radar data assimilation in improving the NWP rainfall forecasts that have direct benefits for hydrological applications. The Weather Research and Forecasting (WRF) model is adopted to generate 10 km rainfall forecasts for a 24 h storm event in the Brue catchment (135.2 km 2 ) located in southwest England. Radar reflectivity from the lowest scan elevation of a C-band weather radar is assimilated by using the three-dimensional variational (3D-Var) dataassimilation technique. Considering the unsatisfactory quality of radar data compared to the rain gauge observations, the radar data are assimilated in both the original form and an improved form based on a real-time correction ratio developed according to the rain gauge observations. Traditional meteorological observations including the surface and upper-air measurements of pressure, temperature, humidity and wind speed are also assimilated as a bench mark to better evaluate and test the potential of radar data assimilation. Four modes of data assimilation are thus carried out on different types/combinations of observations: (1) traditional meteorological data; (2) radar reflectivity; (3) corrected radar reflectivity; (4) a combination of the original reflectivity and meteorological data; and (5) a combination of the corrected reflectivity and meteorological data. The WRF rainfall forecasts before and after different modes of data assimilation are evaluated by examining the rainfall temporal variations and total amounts which have direct impacts on rainfall-runoff transformation in hydrological applications. It is found that by solely assimilating radar data, the improvement of rainfall forecasts are not as obvious as assimilating meteorological data; whereas the positive effect of radar data can be seen when combined with the traditional meteorological data, which leads to the best rainfall forecasts among the five modes. To further improve the effect of radar data assimilation, limitations of the radar correction ratio developed in this study are discussed and suggestions are made on more efficient utilisation of radar data in NWP data assimilation.

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Investigation of a heavy rainfall event over southwestern Taiwan associated with a subsynoptic cyclone during the 2003 Mei-Yu season

Cited by 33 publications

References 18 publications

Analysis of a Warm-Season Surface-Influenced Mesoscale Convective Boundary in Northwest Mississippi

Analysis of a Warm-Season Surface-Influenced Mesoscale Convective Boundary in Northwest Mississippi

Numerical modeling and analysis of the effect of complex Greek topography on tornadogenesis

A study on WRF radar data assimilation for hydrological rainfall prediction

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