Diurnal Variation of Precipitable Water over a Mountainous Area of Sumatra Island

Wu, Peng; Hamada, Junji; Mori, Shuichi; Tauhid, Yudi Iman; Yamanaka, Manabu D.; Kimura, Fujio

doi:10.1175/1520-0450(2003)042<1107:dvopwo>2.0.co;2

Cited by 84 publications

(77 citation statements)

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“…Mixed (or mixing) layer development by strong solar heating has been reported by observational studies (Wu et al 2003;Hadi et al 2000;Hashiguchi et al 1996) and modeling study (Sasaki et al 2004). Murata et al (2006) suggested that a mixed layer develops when synoptic-scale SCCs move to the east of Sumatra, because cloud cover decreases and solar heating increases.…”

Section: Relative Humiditymentioning

confidence: 83%

“…Below the enhanced stability layer at 2.5-3.5 km, a weakened stability layer (dy/dz of smaller 3 K km À1 ) appeared after 7 May. A mixed layer which develops over the land region of the Indonesian Maritime Continent by strong solar heating were studied by Sasaki et al (2004), Wu et al (2003), Hadi et al (2000), and Hashiguchi et al (1996). Murata et al (2006) suggested that a mixed layer develops when synoptic-scale SCC moves to the east of Sumatra, because cloud cover decreases and solar heating increases at that time.…”

Section: Temperaturementioning

confidence: 99%

“…It is located at the eastern edge of the Indian Ocean (around 100 E), and has a high mountain range along its southwestern coastline. Several studies have suggested that local circulation caused by Sumatra's topography plays an important role in formation of convection with a diurnal cycle Sasaki et al 2004;Wu et al 2003).…”

Section: Introductionmentioning

confidence: 99%

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Observational Study on Westerly Wind Burst over Sumatra, Indonesia by the Equatorial Atmosphere Radar A Case Study During the First CPEA Campaign

Seto

Yamamoto

Hashiguchi

et al. 2006

Journal of the Meteorological Society of Japan

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This study focuses on features of vertical wind and cloud distributions in Sumatra during the initial phase of a westerly wind burst (WWB) associated with a synoptic-scale super cloud cluster (SCC), by mainly using radar, radiosonde, and lidar data from 5 to 9 May 2004. The convective envelope of the SCC reached Sumatra from the Indian Ocean on 5 May, passing over Sumatra on 7 May. Intensification of the westerly wind occurred over Sumatra below 5.5-6.0 km as the SCC passed over it. On 7 May, the 2.5-4.0 km westerly wind at Kototabang (KT; 0.2 S, 100.32 E, 865 m MSL) was identified as a WWB. Precipitating clouds around KT were suppressed after 7 May, as drier air (lower than 60% relative humidity) was transported from the Indian Ocean over Sumatra at 2.5-6.0 km. Non-precipitation clouds were observed at 5-8 km by the lidar after 7 May.After 7 May, the vertical wind at 2.5-5.5 km showed the oscillatory motion with a timescale of about 12 hours. Similar oscillatory motion was found in the 1.5-2.5 km zonal wind. Contrary to the Corresponding author: Masayuki Yamamoto, Research Institute for Sustainable Humanosphere (RISH), Kyoto University, Uji, Kyoto 611-0011, Japan. E-mail: m-yamamo@rish.kyoto-u.ac.jp ( 2006, Meteorological Society of Japan radiosonde-derived downward wind with a horizontal scale of several hundred km, daily-averaged vertical wind at KT showed upward motion of 0.07-0.08 m s À1 on 7 and 8 May, when westerly winds larger than 10 m s À1 prevailed at 2.5-4.0 km. These facts imply that the topography around KT, which has steep mountains to the west, modulates the behaviors of the vertical wind.The vertical wind oscillation was suppressed above 3.0-5.5 km, where the Richardson number (Ri) was smaller than 0.45 and westerly wind changed to easterly wind. The small Ri was brought about by strong vertical wind shear (larger than 10 m s À1 km À1 ) and/or weak vertical gradient of potential temperature (smaller than 3 K km À1 ). Both regions appeared at the upper part of the westerly wind region. This fact implies that shear instability and horizontal wind change inhibit upward propagation of vertical wind oscillations.

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Section: Relative Humiditymentioning

confidence: 83%

Section: Temperaturementioning

confidence: 99%

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Observational Study on Westerly Wind Burst over Sumatra, Indonesia by the Equatorial Atmosphere Radar A Case Study During the First CPEA Campaign

Seto

Yamamoto

Hashiguchi

et al. 2006

Journal of the Meteorological Society of Japan

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“…However, due to the relatively coarse horizontal resolution of the models, it was noted that the climate change signal could quite possibly manifest itself differently at smaller scales-particularly for relatively small island countries which are crudely (if at all) represented on model grids with horizontal resolutions of the order of several hundred kilometers. The existence of (unresolved by models) large mountain peaks and valleys can introduce local circulations such as mountain and valley breezes, katabatic winds, and rain shadow effects, while detailed coastal boundaries and contrasting land surface types can also be important in shaping diurnal cycles of rainfall [Holland and Keenan, 1980;Liberti et al, 2001;Wu et al, 2003;Mori et al, 2004;Byon and Lim, 2005;Sakurai et al, 2005;Biasutti et al, 2012]. This is particularly true in the case of New Guinea where rainfall varies considerably over relatively small scales [Zhou and Wang, 2006].…”

Section: Introductionmentioning

confidence: 99%

Regional‐scale rainfall projections: Simulations for the New Guinea region using the CCAM model

et al. 2013

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[1] A common problem with global climate models is the fact that their grids do not always resolve important topographic features which determine the spatial variability of rainfall at regional scales. Here we present and compare simulations of rainfall for the relatively mountainous New Guinea region from six relatively coarse resolution climate models and the corresponding results using a higher resolution model (the Conformal Cubic Atmospheric Model-CCAM). While the large-scale climatological mean rainfall from both the coarse models and CCAM tend to be similar, unsurprisingly, the CCAM results better reflect some of the important topographic effects. However, the results for projected changes (under the A2 emissions scenario) to rainfall for later this century reveal some important differences. The coarse-scale results indicate relatively smooth patterns of projected change consistent with the representations of the underlying topography, but over New Guinea, there is little agreement on the sign of the change. The CCAM projections show greater spatial detail and better agreement among the six members. These indicate that West Papua and the relatively wet northern and southern mountain slopes may get wetter during December to February-the peak of the Austral monsoon season, and the highland regions may actually become drier during June to August-the dry season. These results are consistent with the theoretical concept that warmer temperatures may lead to increases over already wet regions and decreases over the relatively drier regions-the so-called "rich-get-richer" mechanism. They also highlight the fact that the climate of mountainous regions can be relatively complex and indicate potential difficulties that can arise when attempting to synthesize regional-scale projections from coarse-scale models.

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“…Previous and ongoing studies using these instruments, as well as intensive rawinsonde soundings and satellite observations, have revealed several unique and interesting characteristics of precipitating cloud systems over this region, such as a diurnal land-sea rainfall peak and cloud cluster migrations Sakurai et al 2005), diurnal variations in precipitable water associated with local circulations (Wu et al 2003;Sasaki et al 2004), multi-scale interactions of convections and vertical wind variations associated with intraseasonal variation/oscillation (ISV/ISO; Seto et al 2004;Shibagaki et al 2006a), and type classifications of precipitating clouds and associated DSD variations (Renggono et al 2001;Kozu et al 2005). The VWP characteristics of precipitating cloud systems, however, have not yet been studied at sufficient temporal and spatial resolutions over this region or other tropical regions; this is despite the importance of VWPs in the dynamical and thermodynamical processes of precipitating clouds and in interactions with surrounding environments through latent heat releasing processes.…”

Section: Introductionmentioning

confidence: 99%

Vertical Wind Characteristics in Precipitating Cloud Systems over West Sumatera, Indonesia, Observed with Equatorial Atmosphere Radar: Case Study of 23-24 April 2004 during the First CPEA Campaign Period

Mori

Hamada

Yamanaka

et al. 2006

Journal of the Meteorological Society of Japan

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Characteristics of vertical wind profiles (VWPs) in precipitating clouds were studied over western Sumatera (or Sumatra) Island of the Indonesian maritime continent during the first Coupling Process VWPs were precisely measured with the EAR directly in precipitating clouds, which were identified using simultaneous XDR observation. A super-cloud cluster (SCC) system of the intraseasonal variation (ISV) onset phase was examined as a case study. The SCC consisted of three cloud clusters (CCs), which were further partitioned into convective and stratiform cloud regions based on the XDR reflectivity fields. Vertical winds varied greatly in time and height according to variations in the reflectivity fields. Although the VWPs for each CC showed quite scattered variations in time and height, they had significant dependence on the corresponding 10 dBZ radar echo top heights (H 10 dBZ s). Spectral representations of vertical wind and reflectivity profiles, which were stratified by H 10 dBZ heights, showed the following distinct characteristics: 1) Convective spectra were divided into two groups by H 10 dBZ ¼ 10 km. The shorter spectra had massive reflectivity, especially in the lower height with upward currents; the taller spectra had a gentle reflectivity profile with significant upward currents around H 10 dBZ and apparent downward currents below 8 km in height. 2) Spectra for stratiform clouds were partitioned into three groups by H 10 dBZ ¼ 6 and 8 km. Beside the shortest group of shallow stratiform clouds, bright band signs were intensified as the H 10 dBZ increased in the taller two groups. The heights of the maximum upward currents above their bright bands also increased too with the heights of H 10 dBZ .The reflectivity spectra and VWPs are discussed in comparison to global precipitation spectra observed by the Tropical Rainfall Measuring Mission (TRMM) satellite and VWPs calculated by rawinsonde sounding array data, respectively.

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Diurnal Variation of Precipitable Water over a Mountainous Area of Sumatra Island

Cited by 84 publications

References 20 publications

Observational Study on Westerly Wind Burst over Sumatra, Indonesia by the Equatorial Atmosphere Radar A Case Study During the First CPEA Campaign

Observational Study on Westerly Wind Burst over Sumatra, Indonesia by the Equatorial Atmosphere Radar A Case Study During the First CPEA Campaign

Regional‐scale rainfall projections: Simulations for the New Guinea region using the CCAM model

Vertical Wind Characteristics in Precipitating Cloud Systems over West Sumatera, Indonesia, Observed with Equatorial Atmosphere Radar: Case Study of 23-24 April 2004 during the First CPEA Campaign Period

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