Diurnal Variation of Water Vapor over the Central Tibetan Plateau during Summer.

Kuwagata, Tsuneo; Numaguti, Atusi; Endo, Noritaka

doi:10.2151/jmsj.79.401

Cited by 65 publications

(68 citation statements)

References 17 publications

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“…Afternoon convection over the mountain ranges suggests convergence induced by a local circulation (Kuwagata and Kimura 1997). The meridional width ( 150 km) and depth ( 1,000 m) of valley B are similar to the most effective topographic scales for water transport (160 km width and 1000 m depth) shown in Kuwagata et al (2001). Characteristic valley scales over the southern TP efficiently trigger afternoon moist convection over the mountain ranges.…”

Section: Discussionmentioning

confidence: 64%

“…The major mountain ridges and valleys of the TP are aligned east-west (c.f., Fig. 1a), and valleys are 100 300 km wide; Kuwagata et al (2001) used a numerical model to show that this width is a very effective topographic scale for transport of water vapor by thermally induced circulation during the summer. They also noted that the diurnal cycle of PW over the TP results from water vapor transport by the local circulation.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of Diurnal Variations in Convection and Precipitation over the Southern Tibetan Plateau during Summer

Fujinami

Nomura

Yasunari

2005

SOLA

103

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This study investigated diurnal cycles in convection and precipitation over the complex mountain-valley terrain of the southern Tibetan Plateau (TP) during the mature phase of the summer monsoon. Cloud-cover frequency (CCF) for high cloud increased after 13 LST (07 UTC) over the mountain ranges along 28.5°N and 30.2°N, reaching a maximum near 18 LST (12 UTC). Areas of high CCF subsequently moved towards the valley area along 29.3°N; relatively high CCF persisted there until early morning. Tropical Rainfall Measuring Mission (TRMM) PR data show a nearly identical variation in rainfall frequency. Formation and development of convective-type clouds and phase differences in the diurnal cycle were strongly affected by TP topography. Possible mechanisms for convective enhancement over the southern TP are also discussed.

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Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Characteristics of Diurnal Variations in Convection and Precipitation over the Southern Tibetan Plateau during Summer

Fujinami

Nomura

Yasunari

2005

SOLA

103

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“…Since a large sensible heat flux and a deep mixed layer are observed over the plateau during the premonsoon period, sensible heat from the surface is presumed to be directly transported into the upper-level atmo-sphere by dry convection (Yanai and Li 1994). During the monsoon period, on the other hand, the latent surface heat flux and precipitation become large, and quite active cumulus convection can then be observed using the infrared (IR) sensor of the Geostationary Meteorological Satellite (GMS) (Murakami 1983;Yanai and Li 1994;Ueno 1998;Kuwagata et al 2001;Fujinami and Yasunari 2001). These facts indicate that latent heat released by cumulus convection is the major heat source during the monsoon period.…”

Section: Introductionmentioning

confidence: 99%

Relationship between Topography and Daytime Cloud Activity around Tibetan Plateau.

Kurosaki

Kimura

2002

Journal of the Meteorological Society of Japan

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The relationship between topography and daytime cloud activity over the Tibetan Plateau and surrounding areas was examined by using Geostationary Meteorological Satellite (GMS) Visible (VIS) and Infrared (IR) images during the premonsoon, and monsoon periods in 1998. Previous studies using IR images have already confirmed the strong diurnal variation of convective activity over the Tibetan Plateau. This study relies primarily on VIS images to analyze daytime cloud distribution because VIS images are more adaptable to low-level clouds and they offer better spatial resolution than IR images. IR images are used to judge whether cloud tops are high or low. High-level clouds are prominent over the large-scale (100-300 km) mountain ranges, but fewer clouds are observed in the major valleys in the plateau during premonsoon and monsoon periods at 15 Local Solar Time (LST), when the amount of cloud cover is at its maximum from 09 LST to 15 LST. However, the relationship between cloud distribution and topography is not always clear when the horizontal scale of the topography is less than 100 km.Less cloud coverage was observed over the plateau in the morning during the premonsoon period. On the contrary, clouds frequently appeared over the southeastern part of the plateau in the morning during the monsoon period. Low-level clouds often cover the southern slope of the Himalayas, and the frequency of cloud coverage exceeds 75% at 15 LST in the monsoon period. While the cloud tops are growing high elevation in the afternoon over the plateau, low-level clouds cover the southern slope of the Himalayas through the daytime (09-15 LST).

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“…Kimura and Kuwagata (1995), and Kuwagata et al (2001) simulated the phase and amplitude of the diurnal PWV cycle associated with mountain-valley circulations. The daily minimum of PWV appears around noon in a narrow (20 km or 40 km) valley bottom, while it appears later in the bottom of a wider valley.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, Kuwagata et al (2001), analyzing sounding data, indicated that the daytime decrease in precipitable water vapor (PWV) is due to thermally-induced local circulation during the summer. Takagi et al (2000) indicated that PWV reaches its minimum level in the evening.…”

Section: Introductionmentioning

confidence: 99%

Drastic Evening Increase in Precipitable Water Vapor over the Southeastern Tibetan Plateau

Sasaki¹,

Wu²,

Kimura

et al. 2003

Journal of the Meteorological Society of Japan

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A drastic increase in precipitable water vapor (PWV) in the evenings was repeatedly confirmed in October 2000, by an analysis of GPS observational data at Lhasa in the southeastern Tibetan Plateau, China. In order to investigate its mechanism, a numerical simulation was performed for a typical day using a regional atmospheric model. During the daytime, moisture is transported toward the summits of the Himalayas from the Hindustan plain along the southern slope of the mountain range by thermallyinduced upslope winds. The moist air mass penetrates the Tibetan Plateau, through some cols of the Himalayas. Moisture accumulates over the northern foot of the Himalayas. Then a horizontal gradient of moisture increases north of the Himalayas, and a stationary moisture front forms between the moist air mass and dry air on the Tibetan Plateau. In the evening, the frontal structure begins to gradually decay until the midnight, and a large amount of moisture bursts toward the inner Tibetan Plateau in the lower atmosphere as a gravity current, causing a rapid increase in PWV. It is speculated, therefore, that the drastic evening increase in PWV, extending widely along the Himalayas, is generated by the plateau scale diurnal wind induced by the thermal effects between the Tibetan Plateau and the Hindustan plain. During the following day, the PWV level decreases over a wide area of the inner Tibetan Plateau, since dry air advection is intensified in the lower atmosphere by the synoptic scale westerly winds, because of the growth of the mixed layer accompanied by the vertical transportation of momentum.

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Diurnal Variation of Water Vapor over the Central Tibetan Plateau during Summer.

Cited by 65 publications

References 17 publications

Characteristics of Diurnal Variations in Convection and Precipitation over the Southern Tibetan Plateau during Summer

Characteristics of Diurnal Variations in Convection and Precipitation over the Southern Tibetan Plateau during Summer

Relationship between Topography and Daytime Cloud Activity around Tibetan Plateau.

Drastic Evening Increase in Precipitable Water Vapor over the Southeastern Tibetan Plateau

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