Seasonal and Diurnal Variations in Rainfall Characteristics over the Tropical Asian Monsoon Region Using TRMM-PR Data

Takahashi, Hiroshi G.

doi:10.2151/sola.12a-005

Cited by 23 publications

(28 citation statements)

References 28 publications

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“…It can be seen that general spatial pattern of precipitation simulated by the model is in good agreement with TRMM. The model could reproduce high amounts of precipitation over the Bay of Bengal, the South China Sea, and the Western Ghats, in agreement with a number of past studies (Wang and LinHo, 2002;Hirose and Nakamura, 2005;Xie et al, 2007;Takahashi, 2016). However, the model underestimates the rainfall over northern India and the western coast of India by ∼ 2-10 mm day −1 and overestimates it over the Tibetan Plateau (TP) and the South China Sea by ∼ 5-12 mm day −1 .…”

Section: Comparison With In Situ Measurementssupporting

confidence: 88%

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

et al. 2017

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Abstract. Recent satellite observations show efficient vertical transport of Asian pollutants from the surface to the upper-level anticyclone by deep monsoon convection. In this paper, we examine the transport of carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), into the monsoon anticyclone using of ECHAM6-HAM, a global aerosol climate model. Further, we investigate impacts of enhanced (doubled) carbonaceous aerosol emissions on the upper troposphere and lower stratosphere (UTLS), underneath monsoon circulation and precipitation from sensitivity simulations.The model simulation shows that boundary layer aerosols are transported into the monsoon anticyclone by the strong monsoon convection from the Bay of Bengal, southern slopes of the Himalayas and the South China Sea. Doubling of emissions of both BC and OC aerosols over Southeast Asia (10 • S-50 • N, 65-155 • E) shows that lofted aerosols produce significant warming (0.6-1 K) over the Tibetan Plateau (TP) near 400-200 hPa and instability in the middle/upper troposphere. These aerosols enhance radiative heating rates (0.02-0.03 K day −1 ) near the tropopause. The enhanced carbonaceous aerosols alter aerosol radiative forcing (RF) at the surface by −4.74 ± 1.42 W m −2 , at the top of the atmosphere (TOA) by +0.37 ± 0.26 W m −2 and in the atmosphere by +5.11 ± 0.83 W m −2 over the TP and Indo-Gangetic Plain region • N, 80-110 • E). Atmospheric warming increases vertical velocities and thereby cloud ice in the upper troposphere. Aerosol induced anomalous warming over the TP facilitates the relative strengthening of the monsoon Hadley circulation and increases moisture inflow by strengthening the cross-equatorial monsoon jet. This increases precipitation amounts over India (1-4 mm day −1 ) and eastern China (0.2-2 mm day −1 ). These results are significant at the 99 % confidence level.

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Section: Comparison With In Situ Measurementssupporting

confidence: 88%

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

et al. 2017

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“…Precipitation intensity was highest during the premonsoon season in regions B and C, although precipitation intensity was basically unchanged during the premonsoon and monsoon seasons in regions A and D. A higher precipitation intensity corresponded to lower soil moisture conditions in regions B and C during the premonsoon period and the beginning of the rainy season. This highest precipitation intensity during the premonsoon season was also observed by TRMM‐PR [ Takahashi , ], which indicates the observed seasonal changes in precipitation intensity was reliable.…”

Section: Resultsmentioning

confidence: 99%

Seasonal transition of precipitation characteristics associated with land surface conditions in and around Bangladesh

Ono

Takahashi

2016

JGR Atmospheres

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This study examined the seasonal transition of precipitation characteristics and its association with land surface conditions in and around Bangladesh, where land surface conditions are predominantly wet. Hourly rain rate data from the Global Satellite Mapping of Precipitation Microwave‐Infrared Combined Product and 10 day soil moisture data from the Advanced Microwave Scanning Radiometer Earth Observing System were used over the 7 years from 2003 to 2009. Area mean values of soil moisture, and precipitation amount, frequency, and intensity were calculated for each 10 day period. Results showed that higher precipitation amount and frequency were observed over the wet soil conditions, which indicates that soil moisture was influenced by previous precipitation events. However, the soil moisture could also control the precipitation characteristics. The seasonal and interannual variations in all regions suggested that precipitation amount and frequency increased in moist soil conditions, which is associated with an increase of water vapor supplied from the moist land surface. Over a flat plain (87°E–91°E, 23°N–25°N), a higher afternoon precipitation intensity was observed over drier land surfaces. This relationship was observed on seasonal and interannual variations. This suggests that the land surface conditions in this region can affect the afternoon precipitation intensity to some extent, although changes of atmospheric conditions can be a major factor particularly for the seasonal changes. However, this relationship was not observed in mountainous regions. This can be explained by other factors, such as thermally induced local circulations by the surrounding topography, being stronger than the impact of land surface conditions.

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“…However, the observed diurnal rainfall peak in the pre-monsoon season moves from regions M (15:00 LT) and S (15:00-16:00 LT) through region C (17:00 and 04:00 LT) to region N (18:00 LT), and this phase shift cannot be explained in relation to the distance to mountains and the prevailing large-scale southeasterly flow. Although Takahashi (2016) showed by satellite data that precipitation ended in the evening in April and May and lasted until early morning from July to September over the Indochina Peninsula, such characteristics have been recognized only at coastal station C1. Most of the rainfall in inland Cambodia is observed to occur in the afternoon in both the pre-monsoon and the summer monsoon seasons, except for the dominant evening rainfall in the summer monsoon season in region N.…”

Section: Intra-seasonal Variability and Synoptic-scale Influencesmentioning

confidence: 99%

“…Although many studies exist on the climatology and rainfall in the Indochina Peninsula (Nieuwolt 1981;Matsumoto 1997;Satomura 2000;Ohsawa et al 2001;Okumura et al 2003;Xie et al 2006;Takahashi et al 2010a;Satomura et al 2011;Takahashi 2013;Takahashi 2016), limitations of the automatic rain-gauge network in Cambodia have led preceding studies of rainfall in Indochina to use rain-gauge data from mostly only neighboring countries and/or satellite data. As mentioned by Takahashi et al (2010a), rain-gauge observations were inadequate for analyzing the diurnal cycle of rainfall over the Indochina Peninsula because of their limited availability, whereby gauges have only been located in populated and low-altitude areas until very recently.…”

Section: Limitations and Importance Of Studying Rainfall In Cambodiamentioning

confidence: 99%

Diurnal pattern of rainfall in Cambodia: its regional characteristics and local circulation

Tsujimoto

Ohta²,

Aida

et al. 2018

Prog Earth Planet Sci

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We analyze the hourly rainfall data of 30 rain gauges in Cambodia from 2010 to 2015 to focus on the diurnal pattern of rainfall and its regional characteristics, with the underlying mechanisms inferred from the observed data. The observed annual rainfall in inland Cambodia ranges from 1087 to 1528 mm on station-average. Approximately 5-20% of the annual rainfall occurs during the pre-monsoon season, 50-78% during the summer monsoon season, and 12-36% during the post-monsoon season. During the pre-monsoon season, rainfall is dominant on the coast and over the Cardamom Mountains, with a maximum in the afternoon. The rainfall amount is smaller around the Tonle Sap Lake. During the summer monsoon season, rainfall is larger in the northern region and smaller in the western region in inland Cambodia, in both amount and proportion to annual rainfall. The rainfall amount on the coast is distinctively large. The diurnal rainfall maximum occurs in the early afternoon in the Cardamom Mountains, in the afternoon on the plain at the southwestern side of the Tonle Sap Lake, in the evening on the wide area of the northeastern side of the lake, and in the early morning on the coast. The clear regional characteristics in the diurnal rainfall pattern suggest significant effects of local features, even during the Asian summer monsoon season. During the post-monsoon season, rainfall is larger on the southwestern side of the Tonle Sap Lake with dominant nocturnal rainfall. These diurnal patterns are, however, not clear on some days, and analysis of the synoptic-scale atmospheric condition suggests the effect of the large-scale low-pressure system and disturbances on the appearance of the clear diurnal rainfall pattern. The effect of land-lake and mountain-valley circulations on forming the diurnal rainfall pattern is also implied from ground-observed meteorological data, although further numerical studies are required to examine the detailed mechanisms. The study of local effects on rainfall with consideration of the landsurface dynamics may aid flood and drought management in Cambodia by facilitating a greater understanding of its rainfall pattern.

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Seasonal and Diurnal Variations in Rainfall Characteristics over the Tropical Asian Monsoon Region Using TRMM-PR Data

Cited by 23 publications

References 28 publications

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

Seasonal transition of precipitation characteristics associated with land surface conditions in and around Bangladesh

Diurnal pattern of rainfall in Cambodia: its regional characteristics and local circulation

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