Diagnosed Characteristics of Precipitation Systems over Taiwan during the May–June 1987 TAMEX

Johnson, Richard H.; Bresch, James F.

doi:10.1175/1520-0493(1991)119<2540:dcopso>2.0.co;2

Cited by 72 publications

(61 citation statements)

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“…Among these weather systems, convective afternoon rainfall (hereafter, CAR) is the most frequently observed pattern (Wang and Chen 2008). Because of its importance to local residents, the characteristics and causes of CAR have been examined in many studies (Chen et al 1991;Johnson and Bresch 1991;Kerns et al 2010;Lin et al 2011;Huang and Chan 2012;Wang et al 2013). Studies have noted that CAR generally occurs on a day associated with a stronger sea breeze circulation during the daytime (e.g., Lin et al 2012).…”

Section: Introductionsupporting

confidence: 92%

“…Using WRF-HiRAM and WRF-MRI as examples, the present-day simulations (Fig. 10a) show that the daytime near-surface wind over Taiwan is mainly modulated by: (1) sea-breeze convergence, (2) upslope flow, and (3) orographic lifting of prevailing southwesterly flow (e.g., Johnson and Bresch 1991). By examining the difference between the future and present-day near-surface wind change at 14 LT (Fig.…”

Section: Future Projectionsmentioning

confidence: 95%

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Summer Convective Afternoon Rainfall Simulation and Projection Using WRF Driven by Global Climate Model. Part I: Over Taiwan

Huang¹,

Chang

Cheng

et al. 2016

Terr. Atmos. Ocean. Sci.

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This paper is the first of a two-part study that investigates summer convective afternoon rainfall (CAR) activity over the East Asian continent through simulation and projection. We focus on the CAR activity over Taiwan in Part I. In Part II, the changes in CAR activity over South China and Luzon are examined. Using the WRF (Weather Research and Forecasting) model driven by two super-high resolution global climate models: HiRAM (High Resolution Atmospheric Model) and MRI (Meteorological Research Institute Atmospheric General Circulation Model), this study evaluates the performance of models (HiRAM, MRI, and WRF) used to simulate the summer CAR activity over Taiwan. The evaluations focus on the spatialtemporal variations in CAR activity during two time periods: the present-day (1979 -2003, historical run) and the future (2075 -2099, RCP8.5 scenario). For the present-day simulations, analyses indicate that both HiRAM and MRI cannot accurately simulate the temporal evolution of diurnal rainfall. This timing shift problem can be fixed after dynamical downscaling using WRF. The WRF dynamical downscaling approach also helps generate a more realistic CAR amount simulation over western Taiwan, where most residents live. In future projections all models predict that a significant decrease in CAR amount will occur over southwest Taiwan. This decrease in CAR amount is suggested due to the decrease in CAR frequency, not a change in the CAR rate. All models suggest that the cause of decrease in CAR frequency over southwest Taiwan is weaker local afternoon surface wind convergence and thermal instability to suppress CAR genesis.

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Section: Introductionsupporting

confidence: 92%

Section: Future Projectionsmentioning

confidence: 95%

Summer Convective Afternoon Rainfall Simulation and Projection Using WRF Driven by Global Climate Model. Part I: Over Taiwan

Huang¹,

Chang

Cheng

et al. 2016

Terr. Atmos. Ocean. Sci.

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“…In a study of convection over Taiwan, Johnson and Bresch (1991) suggested that the land breeze flow at night was augmented by evaporation of the previous evening's precipitation over the interior elevated terrain. Mapes et al (2003) proposed that the land breeze by itself was inadequate to account for nocturnal convection that regularly occurs offshore Columbia in the Panama Bight.…”

Section: Introductionmentioning

confidence: 98%

Diurnal Cycle of Monsoon Convection

Johnson

2011

The Global Monsoon System

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The diurnal variability of monsoon precipitation and associated circulation features, e.g. land/sea breezes, mountain/valley breezes, and low-level jets, in the monsoon regions of the world are reviewed, with a particular focus on the Asian monsoon. The dominant pattern of diurnal variability is a maximum in rainfall over land during the afternoon/evening in response to solar heating of the surface and a morning maximum over the oceans; however, there are important exceptions to this pattern over both land and ocean. Nocturnal maxima in rainfall are found over land in proximity to major mountain barriers, e.g., at the foot of the Himalayas; downstream of the Tibetan Plateau, the Rocky Mountains, and the Andes; and within interior basins such as the Sichuan Basin. Daytime maxima in rainfall are observed over partially enclosed seas such as the Bay of Bengal, the South China Sea, and the Gulf of Guinea. These latter regions are characterized by seaward propagation of convection from adjacent coastlines.The mechanisms for the diurnal cycle of convection over land, particularly the afternoon maximum in precipitation, are generally well understood, but the timing of precipitation is often not well handled in models. Several theories for the diurnal cycle over the ocean have been proposed, involving surface and free-tropospheric radiative heating or their horizontal gradients; however, the precise mechanisms remain unclear and are not well represented in global models. Mechanisms for propagation of convective systems over both land and ocean are not completely understood and require further research.

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“…Orographic effects on rainfall over the western, windward slopes of the CMR during the 1987 Mei-yu season, part of the southwesterly monsoon regime, have been studied extensively (Yeh and Chen 1998). summarized the orographic effects on the 1987 Mei-yu into lifting (Yeh and Chen 1998;Trier et al 1990), blocking (Li et al 1997;Akaeda et al 1995), and thermal effects ( Chen et al 1991;Johnson and Bresch 1991;Akaeda et al 1995;Yeh and Chen 1998;Lin and Chen 2002). Recently, Bresch (2001) investigated a morning cloud band with light rain showers parallel to the Taiwan east coast.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Heavy Summer Rainfall in Southwestern Taiwan in Relation to Orographic Effects

Chen

Tao

2004

Journal of the Meteorological Society of Japan

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About a quarter to a half of all rainfall from mid-July through August from 1994 to 2000, on the windward side of southwestern Taiwan, came from convective systems embedded in the monsoon flow associated with the southwesterly monsoon. In this study, the causes of two heavy rainfall events (daily rainfall exceeding 100 mm day À1 over at least three rainfall stations), observed over the slopes and/or lowlands of southwestern Taiwan were examined. Data from the European Center for Medium-Range Weather Forecasts/Tropical Ocean-Global Atmosphere (EC/TOGA) analyses, the rainfall stations of the Automatic Rainfall and Meteorological Telemetry System (ARMTS) and the conventional surface stations over Taiwan, and the simulation results from a regional-scale numerical model were used to accomplish the objectives. In one event, on 9 August 1999, heavy rainfall of up to 393 mm was observed over the windward slopes of southern Taiwan in a potentially unstable environment, with very humid air around 850 hPa. The extreme accumulation was simulated and attributed to orographic lifting effects as preexisting convection did not drift into western Taiwan from the Taiwan Strait.In another event, on 13 August 1994, with a maximum rainfall of 450 mm, westerly flow with potentially unstable and very moist air in the lowest layers, converged with northwesterly flow from the central Taiwan Strait over the southwestern coast. The westerly flow decelerated while approaching Taiwan, resulting in enhanced convergence and upward motion over the coastal area and a high amount of rainfall. In addition, a mesoscale convergence area was produced over the southern Taiwan Strait near the southwestern coast of Taiwan due to synoptic circulations. Some convection formed in the ocean near the southwest coast and drifted inland. This situation also enhanced precipitation over the coastal areas. Northwesterly flow formed over the southwestern slopes as weak westerly flow approached the mountains. As rainwater from the Strait and coastal areas moved eastward toward the slopes, the northwesterly flow transported the rainwater southeastward away from the southwestern slopes. Subsequently, less rainfall occurred over the southwestern slopes than over the coastal areas.

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Diagnosed Characteristics of Precipitation Systems over Taiwan during the May–June 1987 TAMEX

Cited by 72 publications

References 0 publications

Summer Convective Afternoon Rainfall Simulation and Projection Using WRF Driven by Global Climate Model. Part I: Over Taiwan

Summer Convective Afternoon Rainfall Simulation and Projection Using WRF Driven by Global Climate Model. Part I: Over Taiwan

Diurnal Cycle of Monsoon Convection

Characteristics of Heavy Summer Rainfall in Southwestern Taiwan in Relation to Orographic Effects

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