Numerical experiments investigating the orographic effects on a heavy rainfall event over the northwestern coast of Taiwan during TAMEX IOP 13

Lin, Pay Liam; Chen, Yi Leng; Chen, Ching Sen; Liu, Che Ling; Chen, Ching Ying

doi:10.1007/s00703-011-0155-7

Cited by 20 publications

(15 citation statements)

References 22 publications

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“…Thus, the coastline of the Bohai Sea has a complicated form. Previous studies, which explored mechanisms behind the formation and variation of CLLJs, mainly focused on relatively straight coastal area, such as the south and east coast of China (Du et al, ; Lin et al, ) and the west coast of Chile (Q. Jiang et al, ). Their results cannot provide an all‐sided explanation that is suitable for CLLJs occurring in such a complex coastal topography system in Bohai Sea.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Coastal Low‐Level Jets in the Bohai Sea, China, During the Early Warm Season

Zhang

et al. 2018

JGR Atmospheres

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We investigate coastal low‐level jets (CLLJs) in the early warm season during 2006–2011 over the Bohai Sea using a 9‐km horizontal resolution output data from the Weather Research and Forecasting model. CLLJs mainly occur in May when large‐scale low is located over land to the north and the Pacific high is located to the southeast of the study area. The occurrence of the CLLJs exhibits an obvious diurnal cycle with two different peaks: one at night, located mainly in the central region, and the other in the afternoon, located in the northern region with mountains at both eastern and western sides. A momentum budget analysis shows that inertial oscillations, triggered by land‐sea thermal contrast, results in the formation of nocturnal CLLJs in the Bohai Sea. In addition, sensitivity experiments show that the enhanced atmospheric baroclinicity, caused by unbalanced solar radiation over the western mountain of the northern region, dominates the occurrence of afternoon CLLJs in the northern area of the Bohai Sea. Besides that, the eastern topography plays a main role as barrier and, therefore, traps CLLJs by topography blocking to its western side.

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Section: Introductionmentioning

confidence: 99%

Characteristics of Coastal Low‐Level Jets in the Bohai Sea, China, During the Early Warm Season

Zhang

et al. 2018

JGR Atmospheres

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“…BLJs were found over the northwestern Taiwan coast during the early summer rainy season as a result of orographic blocking of the SLLJs by the island terrain (Li and Chen 1998), where they displayed diurnal variation with a maximum in the early morning (Lin et al 2011). The formation of LLJs over the Great Plains (BLJs) is due to inertial oscillations (Blackadar 1957) and shallow baroclinicity produced by the sloping terrain (Holton 1967).…”

Section: Discussionmentioning

confidence: 99%

“…The formation mechanisms could be classified into two types. The first is more related to local diurnal oscillations, such as inertial oscillations (Blackadar 1957; Van de Wiel et al 2010), shallow baroclinicity produced by sloping terrain (Holton 1967) or by land-sea thermal contrast over the coastal regions and orographic blocking (Li and Chen 1998;Lin et al 2011). The second type is more coupled with synoptic or sub-synoptic-scale weather systems, such as isallobaric forcing (Uccellini and Johnson 1979), baroclinicity from the development of extratropical cyclones (Djuric and Damiani 1980;Newton 1967), and diabatic effects (Uccellini et al 1987).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Low-level Jets in Shanghai during the 2008-2009 Warm Seasons as Inferred from Wind Profiler Radar Data

Zhang

Ying

et al. 2012

Journal of the Meteorological Society of Japan

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In order to understand the characteristics of low-level jets (LLJs) over coastal areas of China Continent and its linkages with rainfall during the warm seasons, half-hourly data from a wind profiler radar (WPR) at the Qingpu site during the Meiyu periods of 2008 and 2009 in addition to data from one month prior to and after (non-Meiyu periods) were used to develop a climatology of the LLJs over Shanghai, China. Two peaks in LLJ incidence were revealed at 500-800 m and 2100-2200 m altitudes. Thus, we classified the observed LLJs into two types: (1) boundary-layer jets (BLJs, below 1 km) and (2) synoptic-system-related LLJs (SLLJs, within 1-3 km). BLJs and SLJs showed different behavior in their temporal variation of the occurrence frequency, wind direction, and relation to rainfall. The BLJs displayed a more evident diurnal cycle than the SLLJs, with maximum incidence occurring in nighttime and early morning. The SLLJs occurred more frequently during Meiyu periods than non-Meiyu periods, whereas the occurrence frequency of BLJs increased throughout the warm seasons with no peak during Meiyu periods. BLJs are mostly southerly winds that might be induced by inertial oscillation with a strong background southerly geostrophic wind due to the west-east land-ocean thermal difference. SLLJs most frequently appeared as southwesterly and westerly winds embedded in the East Asian monsoon circulation. The relation between LLJs and precipitation was examined by comparing the frequency of LLJs occurrence on rainy days (cases), with daily (4-hourly) accumulated rainfall within 1 to 10 mm, and non-rainy days (cases) because the missing rate of WPR data is high during heavy rainfall events. Both BLJs and SLLJs occur more often on rainy days than on non-rainy days. In shorter time scales (4 hours), both BLJs and SLLJs tend to occur frequently during, before and after rainy cases, except SLLJs before rainy cases.

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“…Nevertheless, for all three cases studied, localized heavy rainfall occurs at night as the surface front approaches with increasing strength of the pre-frontal southwesterly monsoon flow. Previous studies have shown that orographic blocking is most pronounced at night and in the early morning when the land surface is coldest (Chen and Li 1995b;Kerns et al 2010;Lin et al 2011).…”

Section: Orographic Effects As the Low-level Trough Approaches Taiwanmentioning

confidence: 99%

“…Convective activity could develop or strengthen over the northwest/west coast of Taiwan (Kerns et al 2010) if offshore convergence is coupled with upper-level divergence under favorable largescale conditions (Chen and Li 1995a;Li et al 1997). Furthermore, the strength of the barrier jet is strongest in the early morning when the land surface is coldest (Chen and Li 1995b;Lin et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Revisiting the Heavy Rainfall Event over Northern Taiwan on 3 June 1984

Chen¹,

Chen²,

Chen³

et al. 2013

Terr. Atmos. Ocean. Sci.

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In this study, the mechanisms for the development of a localized heavy rainfall event during the evening of 2 June to the early morning of 3 June 1984 over northern Taiwan are investigated. This event occurred under favorable large-scale conditions including: upper-level divergence; low-level high equivalent potential temperature; low levels of free convection; and subsynoptic-scale ascending motion over the northern Taiwan Strait and northern Taiwan associated with a baroclinic front. In the late night of 2 June, pre-existing rainfall is simulated to the southeast of a trough axis over the southeastern China coast as well as in the frontal zone north of Taiwan. The pre-existing rainfall is enhanced as it moves over the northeastern Taiwan Strait where the prevailing southwesterly winds within the Taiwan Strait converge with the orographically deflected flow with a southerly wind component off the western/northwestern Taiwan coast. As the pre-existing convective rainfall continues to move toward northern Taiwan, it is further enhanced in a localized low-level convergence zone over the northwestern coast where a barrier jet along the coast converges with the northwesterly winds behind the surface front. Furthermore, on the morning of 3 June, focusing of rainfall is simulated where the barrier jet encounters the leading edge of the cold pool caused by rain evaporative cooling. As the convective rainfall areas drift inland, the orographic lifting of the pre-frontal southwesterly flow over the slopes south of the Taipei Basin also plays a role in the simulated enhanced heavy rainfall there.

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Numerical experiments investigating the orographic effects on a heavy rainfall event over the northwestern coast of Taiwan during TAMEX IOP 13

Cited by 20 publications

References 22 publications

Characteristics of Coastal Low‐Level Jets in the Bohai Sea, China, During the Early Warm Season

Characteristics of Coastal Low‐Level Jets in the Bohai Sea, China, During the Early Warm Season

Characteristics of Low-level Jets in Shanghai during the 2008-2009 Warm Seasons as Inferred from Wind Profiler Radar Data

Revisiting the Heavy Rainfall Event over Northern Taiwan on 3 June 1984

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