PROCEEDINGS OF HYDRAULIC ENGINEERING
Online ISSN : 1884-9172
Print ISSN : 0916-7374
ISSN-L : 0916-7374
Volume 48
Displaying 1-50 of 273 articles from this issue
  • Shen CHIANG, Yasuto TACHIKAWA, Kaoru TAKARA
    2004 Volume 48 Pages 1-6
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Flow Accumulation Value (FAV) denotes water accumulates along the flow paths dictated by the topography. For any specific location in a basin, by adjusting FAV to proper units, the flow accumulation is synonymous with drainage area. In this study, by combining DEM and Kinematic Wave routing method, discharge of the surface runoff of specific location inside the basin within given rainfall intensity has been calculated, and water depth and velocity also has been derived. By adopting the concept of IUH and through describing the runoff mechanism, the traveling time of water movement from any specific location of the basin to the outlet is examined; consequently, a distributed instantaneous unit hydrograph of the basin is derived.
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  • Yasuto TACHIKAWA, Gen NAGATANI, Kaoru TAKARA
    2004 Volume 48 Pages 7-12
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    A stage-discharge relationship equation incorporationg saturated-unsaturated flow mechanism is newly devised. A distribited rainfall-runoff model introducing the equation is applied at the Kamishiiba dam catchment (211 km2) in Kyushu, Japan and the model performances are compared with a distributed model using the A-layer flow-surface flow equation and the storage function method. It is shown that simulated hydrographs using the proposed equation show good agreements with observed ones not only peak discharges but also recession parts of hydrographs. The model parameters stability are also highly enhanced by introdusing the proposed stage-discharge relationship equation.
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  • Shuichi KURE, Yuta KOSHIZUKA, Tadashi YAMADA
    2004 Volume 48 Pages 13-18
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The purpose of the present study is to clarify the runoff mechanism from recession characteristics of hydrograph. We proposed a method to explain runoff characteristics and obtained an analytical solution related to recession curve of hydrograph. We can estimate the parameters of the present model from observed data of discharge. Runoff parameters are determined in term of the slope gradient, slope length, thickness of surface soil layer, unsaturated hydraulic conductivity and effective porosity. In our runoff analysis model, runoff characteristics in a basin can beextracted from characteristics of recession curve.
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  • Hideyuki KAMIMERA, Minjiao LU, Norio HAYAKAWA
    2004 Volume 48 Pages 19-24
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The objective of this study is to investigate the applicability of re-analysis data in hydrological forecasting. In this study, flood runoff analysis of the historical 1998 floods occurred in Changjiang and Songhuajiang river basins, China has been carried out by using the GAME re-analysis data (version 1.5). For these two continental river basins, distributed hydrological models with spatial resolution 0.5 by 0.5 degree are built by using our distributed modeling system. For each basin, calculated hydrographs are derived at three hydrological stations. They are compared with the observed ones. It is shown that the flood volume and timing of peak discharge are well represented. This shows that GAME re-analysis data is fully applicable. And this also implies the possibility to apply re-analysis data to hydrological forecasting of the continental scale river basins.
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  • Hiroyasu KATO, Akira MANO
    2004 Volume 48 Pages 25-30
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    This study aims to develop a physics-based flood runoff model to reproduce flood peak discharge at few-day duration in continental-scale rivers. Entire global meteorological data set ISLSCP Initiative I and entire global geographic data set GTOPO30 in USGS were used so that this model can be applied for any continental-scale river basin. To express groundwater, two serial tanks were attached to each sub-basin. Runoff intensities from each tank are expressed as a function of physics-based parameters, water depth in the tank, slope, and hydraulic conductivity according to Darcy's law. As a result of applying this model for the Upper Changjiang river basin in 1987 to 1988, this model reproduces the observed daily discharge at Yichang, the upper reach terminal, over the two years in good accuracy.
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  • Michio HASHINO, Takao TAMURA, Masashi TABUCHI, Yoichi FUJIKAWA
    2004 Volume 48 Pages 31-36
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    A method of separately estimating daily rainfall-interception evaporation and transpiration in forested watersheds is proposed using available 365-daily data of temperature, relative humidity and sunshine duration, as well as rainfall-runoff. A non-linear interception model is developed, and restraints of transpiration under the conditions of low-flow and high pressure defict of saturation vapor are considered. In order to evaluate the storage depth of non-overland-flow separated from observed runoff depths, a runoff-tank model with separated overland-flow is used. The parameter identification of the runoff-tank model is made using storm hourly data of rainfall-runoff besides 365-daily data of temperature, relative humidity, estimated radiation and rainfall-runoff. The maximum storage depth of non-surface flow for a heavy storm with a daily rainfall depth of 391mm in the Okunoi experimental watershed is found to be 98mm, while interception and overland-flow depths are 71 and 208mm, respectively, that are 18 and 52% of the total rainfall depth.
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  • Makoto NAKATSUGAWA, Keisuke KUDO, Kiyoshi HOSHI
    2004 Volume 48 Pages 37-42
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    To facilitate flood prediction and water-resource management, this study examines a method of modeling the storage effect of accumulated snow for the entire watershed. To achieve this, it is necessary to take into account the time lag as a factor depending on the state of accumulated snow.
    We found that the constantly changing storage effect can be parameterized simply, based on the depth of accumulated snow as calculated by long-term hydrologic model. Outflow at the lower surface supplied by infiltration of melt water from the upper surface is then applied to runoff calculation. Reduction in snow accumulation, early onset of snowmelt period and anomalous rainfall patterns due to climatic changes have been concerns in recent years. An attempt was made to propose a generalized runoff model that can be applied under any conditions in cold, snowy regions
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  • Masahiko HASEBE, Yoshiharu SUZUKI, Masanori KAMATA
    2004 Volume 48 Pages 43-48
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The concept of hydrology admits that the river flow in the mountainous basin is contributed to from two major runoff components, that is the runoff components with shorter period and it with longer period. But the river flow in a mixture of mountainous and urban areas is different because the input to the hydrologic systemis different.
    In this paper, we investigate the response characteristics of the YAMATO river basin to be mixed of mountainous and urban areas by filter separation AR method. Like this, it is useful to grasp the runoff structure from the upstream region in the river to lower current area in the basin management.
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  • MUTUALLY INDEPENDENT RAINFALL INPUTS
    Gaku TANAKA
    2004 Volume 48 Pages 49-54
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Responses of a runoff system with slope-length distribution have been studied in detail by many researchers. In those studies, rainfall input to the runoff system was considered a deterministic variable. However, rainfall input should be treated as a random process.
    In this paper, the Kinematic Wave model is used as a runoff system, and differential equations whose solutions provide the first-to fourth-order moments of discharge outputs from the runoff system under the impact of mutually independent rainfall inputs and slope-length distribution are theoreticallyderived. The validity of the proposed differential equations is cross-checked by results of simulation. Estimation of the probability density function of discharge outputs is possible by using the first-to fourth-order moments presented in this paper.
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  • Shuichi KURE, Tadashi YAMADA
    2004 Volume 48 Pages 55-60
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The purpose of the present study is to clarify formation process of the water quality hydrograph. We obtained a partial differential equation to explain the formation of pollutant hydrograph with overland or subsurface flow in a slope. This equation was numerically calculated with a runoff equation. Further, we obtained two ordinary equations to approximately and conveniently express the hydrographs of discharge and water quality. The characteristics of water quality hydrograph observed in mountainous basins can be explained rationally by the method proposed in this paper.
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  • NMNS Bandara NAWARATHNA, So KAZAMA, Masaki SAWAIVIOTO, Kaoru TAKARA
    2004 Volume 48 Pages 61-66
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    BTOPMC (Block wise TOPMODEL with Muskingum-Cunge flow routing method) is an extension of TOPMODEL. The BTOPMC uses the block average saturation deficit instead of basin average value that is proposed in the TOPMODEL to calculate local saturation deficit. In this paper a methodology has been proposed to determine the optimum number of blocks when applying to large scale basins. The model was applied to simulate hydrological processes in the Mekong River basin upstream of Pakse with catchment area of 277, 000 square kilometers. Four parameters namely; lateral transmissivity under saturated conditions To, decay factor m, maximum root zone storage Srmax, and Manning's coefficient n, were assigned depending to land use. The Manning's coefficient along the main stream and tributaries were assigned as a function of slope and the best Manning's coefficient value at the most downstream location. Daily observed discharges at Luang Prabang gauging station were used as an upstream boundary condition to the model. The watershed was divided into several blocks in order to understand the block size effect on hydrological simulations. It was found that the number of blocks which results the minimum standard deviation of block average slope or soil topographic index produces the best hydrological simulation.
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  • Yuzoh SATOMI, Gaku TANAKA
    2004 Volume 48 Pages 67-72
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Spatial resolution of topographic information gives influence to runoff analysis. In general, geophysical phenomena are considered as random process.
    In this paper, the Kinematic Wave model is used as a runoff system, and simulutaneous equations for the first-to fourth-order moments of water depth and concentration time under the impact of rectangular rainfall inputs and slopedistribution are theoretically derived. The validity of the proposed equations is cross-checked by results of a simulation. It is possible to estimate the probability density functions of water depth and concentration time by using the first-to fourth-order moments.
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  • Hiroto SUZUKI
    2004 Volume 48 Pages 73-78
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Maximum 1-, 3-, 6-, 12-, and 24-hour precipitations are important hydrological variables in hydrological engineering. This paper describes the relationship between maximum precipitations based on precipitation data recorded at an interval of one hour, ten minutes, and five minutes for each rainfall event. Ratios of maximum 1-, 3-, 6-, 12-and 24-hour precipitations recorded at an interval of five minutes to ones recorded at an interval of one hour are 1.164, 1.043, 1.022, 1.011 and 1.006 respectively. Similarly ratios of maximum 1-, 3-, 6-, 12-and 24-hour precipitations recorded at an interval of five minutes to ones recorded at an interval of ten minutes are 1.012, 1.005, 1.003, 1.001 and 1.001.
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  • Young-Hoon JIN, Akira KAWAMURA, Kenji JINNO
    2004 Volume 48 Pages 79-84
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    During the latest several decades, there has been considerable interest in revealing the relationship between El Niño/Southern Oscillation (ENSO) and hydro-meteorological variables. The oscillation is characterized by a simple index, the Southern Oscillation Index (SOI). Various approaches have been proposed for detection of correlation between SOI and hydro-meteorological variables. However, some of the approaches present a limited applicability for the data, which cannot be normalized by usual method such as power transformation. When the relationship between pairs is strongly nonlinear, usual Pearson's correlation coefficient also results in the spurious evidence for the relationship.
    In the present study, we propose two nonparametric approaches with the overall purpose to obtain meaningful results from the relationship between SOI and precipitation. A data transformation is proposed for the monthly precipitation data in Fukuoka, Japan. The method transforms the precipitation data into nonexceedance probability time series. Also, Kendall's correlation coefficient, which is a rank-based procedure and can represent a nonlinear relationship between pairs, is used and verified through the comparison with the results by usual methods at the same station.
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  • Tosiyuki NAKAEGAWA
    2004 Volume 48 Pages 85-90
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    This study explores preliminarily the relationship between precipitation in the three regions of Japan and Niño 3 sea surface temperature (SST). The 87-year data set of precipitation and SST are analysed using wavelet analysis. The strong local wavelet power spectrum of precipitation using Morlet wavelet shows significant signals in 2-4 year periods. Decadal variations of the significant power spectrum are found in all reagions and seasons. The decadal power spectrum variations in winter in Kyushu are due to the Rossby wave excited by the tropical SST anomaly.
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  • Tamotsu SHIMIZU, Masahiko HASEBE, Yoshiharu SUZUKI, Mikio HINO
    2004 Volume 48 Pages 91-96
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In recent years, global warming is progressing and increasing CO2 concentration in the atmosphere is generally its major cause. Accordingly many researchers of various fields have been carried out on CO2. But there are many uncertainties on CO2. We considered that it is necessary to make a precise model to clarify these uncertainties. So we thought that it was significant to grasp the variation characteristics of atmospheric CO2 concentration.
    Then, in this paper we investigated to grasp the fluctuation characteristics of atmospheric CO2 concentration, such as the spatiotemporal fluctuation and spatial distribution characteristics, by using the atmospheric CO2 concentration practical data that has been equipped in recent years. Moreover we confirmed how much influence the Mt. Pinatubo Eruption would have had on the atmospheric CO2 concentration fluctuation because it has not been clarified.
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  • Kenjiro SHO, Akihiro TOMINAGA
    2004 Volume 48 Pages 97-102
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    A flood frequency analysis using historical flood information was carried out for Lake Biwa since 18th century. The probability distributions of the standardized annual maximum water level andthe annual maximum rainfall totals for 30days was investigated and the effects of using historical flood information on flood frequency analysis were examined by plotting position. As results, it became apparent that these two extreme hydrological values obey the Gumbel distribution for Lake Biwa, and it was shown that the estimation precision of the quantile corresponding to the return period of several decades to a hundred years is largely improved by utilizing historical flood information.
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  • Jun MAGOME, Kuniyoshi TAKEUCHI, Junko HIRANO, Hiroshi ISHIDAIRA
    2004 Volume 48 Pages 103-108
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The method for monitoring the variation of reservoir storage is presented. Satellite observations are used to estimate the change of storage volume of the reservoirs, where satellite images are applied to detection of water surface and satellite altimetry is used to measure the change of water level. This method has potential to be used for monitoring reservoir storage without in-situ observations, and it could be applied to ungauged or data poor basins.
    The case studies are conducted in 3 large reservoirs in Africa (Akosombo, Victoria and Nasel), and the results of case studies show that the presented method can provide seasonal to inter-annual variability of reservoir storage. In addition, the relation between change of reservoir storage and precipitation is also investigated in these 3 large reservoirs.
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  • Nawa Raj PRADHAN, Yasuto TACHIKAWA, Kaoru TAKARA
    2004 Volume 48 Pages 109-114
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Failure to translate scale dependencies of dominating geomorphometric parameters into effective hydrological models has posed a serious problem for ungauged basins where only coarse resolution elevation data is available. To overcome this problem, scale laws that govern the relation in digital elevation data resolution on geomorphometric parameters of topographic index of TOPMODEL have been analyzed. A scale invariance model for down scaling of topographic index distribution has been developed by introducing a resolution factor and a fractal method for the scaled steepest slope in topographic index. The method successfully derived topographic index distribution of fine resolution DEM by using only coarse resolution DEM. The scale invariance model has been applied to Kamishiiba catchment (210 km2) and it is shown that the down scaled topographic index distribution is similar to a target topographic index distribution.
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  • Yosuke KOMATSU, Yasuhisa KUZUHA, Kunio TOMOSUGI, Tokuo KISHII
    2004 Volume 48 Pages 115-120
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    This paper reports an application of Regional Flood Frequency Analysis (RFFA) to Hokkaido region, northern Japan, where snow-melt flood is predominant. Optimal probability density function for annual maximum flood series was selected from seven fitting methods based on goodness-of-fit-criterion. This paper calculated the scale exponents in the power law relationship between flood quantiles and drainage area in order to evaluate scaling property: e.g. simple scaling or multiscaling. As a result of the analysis, simple scaling holds because the scaling exponents slightly vary between different return period flows.
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  • Roshan SHRESTHA, Yasuto TACHIKAWA, Kaoru TAKARA
    2004 Volume 48 Pages 121-126
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The uncertainty in hydrologic model outputs is the accumulated effects of input data, model structure and process description, which all are also scale dependent features. It is hard to pinpoint the basic reason of uncertainty; however, it is understandable that the dominant reason remains changing on the basis of data type, model structure and parameterization over a range of scale. In this paper, the spatial rainfall structure has been analyzed by spectral observation over a wide range of spatial scale, which presents a good insight to understand the spatial rainfall structure dynamics. The scale dependency of spatial rainfall characteristic is detected as a dominant reason to impart uncertainty in larger scale relative to catchment scale. A significant sensitivity of reference grid position in multi scale frame is also noticed, which displays the extent of anisotropic rainfall structure and its effect on different scale. The Huaihe River basin (132, 350 km2) and its sub-basins are taken as a case study.
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  • Kazuyoshi SOUMA, Kenji TANAKA, Eiichi NAKAKITA, Shuichi IKEBUCHI
    2004 Volume 48 Pages 127-132
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In this study we have coupled land surface process model (SiBUC: Simple Biosphere Mode including Urban Canopy) into nonhydrostatic atmospheric model (ARPS: Advanced Regional Prediction System) developed by CAPS (Center for Analysis and Prediction of Storms). Preliminary test simulation was carried out by ARPS-SiBUC coupled model and ARPS within and surrounding area of the Lake Biwa Basin during the intensified observation period of the Lake Biwa Project 2001. We compare the simulation results of the two models paying attention to the accuracy of the land surface flux and the local circulaton within the Lake Biwa Basin.
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  • Yukitaka OHASHI, Yujiro HIRANO, Yutaka GENCHI, Hiroaki KONDO, Yukihiro ...
    2004 Volume 48 Pages 133-138
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    We investigated air-temperature diurnal variations within urban canopy layer, using a coupled model between the urban meteorology and building energy consumption. The main results obtained are as follows. The coupled model reproduces temperature fields during weekdays when a waste heat exists due to energy consumption and cooling needs in buildings, as well as during weekend. The waste heat causes a temperature rising of 1-2°C during the weekdays at the Tokyo office area. However, the temperature rising strongly depends on weatherconditions (e.g., solar radiation and wind speed); the temperature rising is small when the solar radiation fluxand wind speed increase.
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  • Ryo MORIWAKI, Manabu KANDA, Yuka KIMOTO
    2004 Volume 48 Pages 139-144
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    We investigate shear functions for momentum (φM-1) and heat (φH-1) and linear correlation coefficients of them (-ruw |rwT|) using data acquired over an urban surface layer in Tokyo Japan. Field measurement was conducted on a 29m height tower, 4 times the canopy height of 7.3m. 3D sonic anemometers were installed at 4 heights in the region 1.5zh<z<4zh and fine wire thermocouples were mounted at 10 heights from the ground to the top. Main conclusions were obtained as follows.(1) Momentum flux decreases with height. Non-dimensional horizontal wind velocity follows a conventional stratified logarithmic profile when it is scaled by the shear stress extrapolated to the roof top level. However, the locally scaled wind profile fails the agreement.(2) Both of φM-1 and -ruw have the dependency on height and they are enhanced near the canopy due to the ‘bluff body’ effect.(3) At a height of z/zh =2.7, φM-1 follows the conventional similarity function while -ruw is still larger than a conventional one. The ‘bluff body’ effect appears more significantly in -ruw.(4) Both of ΦH-1 and |rwT| have a good agreement with the conventional function and the dependencies on height are not found. In the case of heat, the conventional similarity theory can be applied to the urban surface layer.
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  • Hiroaki WATANABE, So KAZAMA, Masaki SAWAMOTO
    2004 Volume 48 Pages 145-150
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The NDVI data set is used for the estimation of evapotranspiration. Evapotranspiration in paddy fields is estimated using the solar radiation method instead of NDVI. The estimated flux by NDVI and solar radiation method is compared with single layer model as physical method. As a result of the comparison, the singlelayer model method shows smaller evapotranspiration. Considering the evaporation by canopy interception in singlelayer model, evapotranspiration estimated by both models show the near value in forest area. NDVI method shows smaller evapotranspiration in city area. We understand that NDVI method underestimates evapotranspiration in city area. However, distribution pattern is quite similar and it concludes that NDVI method could estimate evapotranspiration.
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  • Mikio HINO
    2004 Volume 48 Pages 151-156
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The phenomenon of transpiration and latent heat release in stomata of plants is important in relation to the water resources, the suppression of CO2 increase and global warming. Hitherto, the phenomenon is treated by either the Penman-Monteith theory and stomatal conductance or the bulk formula.
    In this paper, the writer proposes two theories from a standpoint of hydraulics. One is a 1D model of a hydraulic system of water-uptake from roots to stomata of leaves, considering the osmatic pressure change resulting from transpiration and photosynthesis. The other is the numerical computation of flow, heat and energy, CO2 and vapour around leaf surface, and in stomata and leaf cells. The theoretical computation explains the micro-mechanisms of transpiration, latent heat release, CO2 assimilation, and would further give a foundation for the conventionally used formulae.
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  • Hironori HIGASHI, Taro OKA
    2004 Volume 48 Pages 157-162
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    This paper describes unsaturated soil characteristics in low moisture content and influences of soil moisture content in evaporation from soil surface. The vapor diffusivity in the soil was measured using the unsteady method proposed by Currie (1960). The water retention curve and the hydraulic conductivity were determined by laboratory experiments using a psychrometer. A numerical analysis for waterand vapor movement in the lysimeter is carried out. The calculated results indicate that the effects of the vapor movement on evaporation are negligible in the lysimeter. A method of estimate for evaporation using the meteorological condition and the soil moisture content is proposed, and its usefulness is confirmed by comparing the calculated and the observed results.
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  • Yuka KIMOTO, Ryo MORIWAKI, Manabu KANDA
    2004 Volume 48 Pages 163-168
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    To investigate the characteristics of potential temperature profiles, a field observation was continuously carried out at a residential site in Tokyo. Following results were obtained; 1) In winter the potential temperature has a maximum value around the roof top level, whereas in summer near the ground surface. The heat source moves up and down due to the seasonal and daily change of solar angle. This isa distinctive characteristic of the micrometeorology of the urban canopy contrast to vegetation canopy. 2) The maximum temperature at the roof top level implies that inversion layer is formed within the canopy. This is directly confirmed by the turbulent flux measurement.
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  • Hiroshi SENOO, Manabu KANDA, Tsuyoshi KINOUCHI, Aya HAGISHIMA
    2004 Volume 48 Pages 169-174
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    To evaluate the impact of urban activities on urban climate, anthropogenic vapor emission as well as anthropogenic heat emission in Tokyo was estimated, and urban climate in summer was simulated. The following results are obtained.
    (1) In winter, anthropogenic heat emissions from residential area are greater than those from business area in summer.
    (2) The maximum value of anthropogenic vapor emission exceeds 400W·m-2 in summer. This value is the same level of anthropogenic heat emission in the central Tokyo.
    (3) Air temperature is increased about 0.5°C and the water vapor mixing ratio is increased 0.1g·kg-1 due to anthropogenic heat and vapor in central Tokyo.
    (4) At north of central Tokyo, the water vapor mixing ratio is increased. Anthropogenic vapor emissions, however, have little contribution to the increasing.
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  • Based on hydro meteorological monitoring data collected in the Kugahara Experimental Site
    Tsuyoshi KINOUCHI, Yu NAKAYAMA, Ryo MORIWAKI, Manabu KANDA
    2004 Volume 48 Pages 175-180
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The water and energy transport dynamics in urban catchments are investigated to facilitate better understanding of thermo-hydrological impact of urbanization on the receiving water. For this purpose, meteorological and hydrological variables have been monitored in a catchment with an area of 12.2ha located in the central Tokyo District. The amounts and dynamic patterns of urban wastewater showed quite reasonable results compared with existing survey reports. The time variation of sewage temperature showed a distinct diurnal pattern, which reflects water and energy consumption characteristicsin residential houses and is insensitive to a day of the week and season. In a thunderstorm event, the impact of summertime urban heating on the runoff was revealed by an abrupt increase of storm temperature. Finally, a dynamical model was proposed to estimate sewage temperature in response to hydrological and meteorological conditions as well as human behavior of water and energy consumption.
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  • Yukiko HISADA, Yuji SUGIHARA, Nobuhiro MATSUNAGA
    2004 Volume 48 Pages 181-186
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In order to examine the structure of urban heat island in the summer season, thermometers havebeen put in 71 instrument shelters of elementary schools in Fukuoka metropolitan area. A typical heat island pattern is seen by using the day-averaging air temperature in this area. The highest temperature of 26.4°C is observedaround Hakata JR Station. The heat island in the summer season appears more clearly in the nighttime, and the temperature inthe urban area falls at the rate of about 0.2°C/km toward the rural area. In the daytime, high temperature region of 28.0°C spreads over the whole area of the metropolitan. The heat island intensities in the nighttime and the daytime are 1.3°C and 1.5°C, respectively. Though the difference between daily maximum temperature and daily minimum temperature is 3.2°C at the region adjacent to Hakata Bay and reaches 5.1°C at an inner areaof Fukuoka plains.
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  • Yasuhide TAKANO, Takeharu ETOH, Kohsei TAKEHARA
    2004 Volume 48 Pages 187-192
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Quality of drainage water from rooftop planting is monitored at Kinki University. Drainage water from greening basement such as artificial soil is analyzed to detect the source of substances in it. These investigationsled to followingc onclusions:
    (1) Drainage water from rooftop planting is rich in NO2-N, NO3-N and PO4-P, which are eutrophic substances to public water bodies such as lakes and ponds.
    (2) These substancesc ome fromn ot only fertilizer or herbicide but also artificial soil and drainage filter.
    Extension of the rooftop planting area increases amount of water demand for planting and discharge of eutrophic substances in drainage water. Water recycle system that collects and reuses rain water and drainage water from rooftop planting is proposed to solve this problem.
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  • Manabu KANO, Taichi TEBAKARI, Tsuyoshi KINOUCHI, Shigeyuki SAKAKI, Tad ...
    2004 Volume 48 Pages 193-198
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The large-scale social experiment, which many citizens including media representative participated for evaluating the effects of the watering on the “Heat Island Effect”, was carried out in Tokyo Metropolitan in Aug. 25 2003. About 14000l. water were sprinkled for about 20 minutes from noon. Air temperature and humidity were measured by moving observation system and fixed observation system at watering area in Eastern Tokyo. After the watering, the air temperature difference between outside and inside of watering area increases, and its difference was about 0.5°C. Temperature of watering area is lower than the temperature of outside area of watering after the watering. The effect of the watering was verified using the numerical simulation based on MM5. As a result of this analysis, air temperature degreased 2-2.5°C in watering area after the watering.
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  • Kenji TANIGUCHI, Toshio KOIKE, Eiji IKOMA, Masaru KITSUREGAWA
    2004 Volume 48 Pages 199-204
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The formation of the strong westerly over the Arabian Sea, which is characterized as the onset of the Indian summer monsoon provides the monsoon rainfall in India. By integrating the data sets of precipitation, outgoing long-wave radiation, cloud amount and sea surface temperature, the seasonal march of the atmospheric and earth surface conditions are examined. Based on the detail investigation of the case of 1999 and 2001, two patterns of process of the monsoon onset are identified; one associated with a cyclone event and the other with the southwest advection into the Arabian Sea but not any cyclone. For the latter cases, this paper shows that a monsoon onset is controlled by the potential temperature gradient between the Arabian Peninsula and the Arabian Sea, and between the Iran-Pakistan region and the Arabian Sea.
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  • Nozomu HIROSE, Toshio KOIKE
    2004 Volume 48 Pages 205-210
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    To evaluate the effect of land surface on atmosphere, spatially averaged evaporation has to be estimated correctly. We developed the model to represent the soil moisture distribution, and showed that soil moisture distribution was important to estimate the spatially averaged evaporation correctly.
    To predict the soil moisture distribution based on spatially averaged soil moisture, we must understand the characteristics of soil moisture by using this model. To do so, availability of this model has to be validated using field observation. At first, based on the field observation, we show the mechanism of formation of the soil moisture distribution which is the basis of the model. Second, the model is applied to four observation sites. As the result, the model simulation agrees with observed soil moisture distribution in each site, quantitatively.
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  • Osamu KOZAN, Kenji TANAKA, Shuichi IKEBUCHI
    2004 Volume 48 Pages 211-216
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In this study, agricultural cycle was estimated from satellite data for the evaluation of agricultural water use in the Huaihe river basin, China. Using SPOT-NDVI data from April 1998 to March 1999, all cropland are categorized into four classes (wheat+soybean, wheat+maize, rape+rice, wheat+rice). Then the harvesting time of summer harvesting crop, the planting and harvesting time of autmun harvesting crop are estimated from the time series of NDVI data at each mesh. Based on these results and water requirement data, appropriate water level and soil moisture condition is defined depending on the growing stage. In the numerical simulation, irrigation water is supplied or drained to meet this appropriate condition. Due to this method, water use of this basin is faithfully reflected in the land sueface scheme.
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  • Toshio KOIKE, Yoshiteru NAKAMURA, Ichiro KAIHOTSU, Gombo DAVAA, Naoto ...
    2004 Volume 48 Pages 217-222
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Soil moisture and water content in vegetation are the key parameters of land-atmosphere interaction, which affect the seasonal and interannual variations of the global and regional water cycle considerably. To monitor these parameters in global and regional scales effectively, an algorithm for the Advanced Microwave Scanning Radiometers (AMSR & AMSR-E) launched in 2002 has been developed in this paper. This paper presents a physically based radiative transfer model by considering the effects of extinction in soil layer and absorption and radiation in vegetation layer and a retrieval algorithm by using the satellite sensor data. A good accuracy of the algorithm is obtained through the algorithm validation in the Mongolia reference site of the Coordinated Enhanced Observation Project (CEOP). Consequently, a soil moisture data set is generated in Mongolia by applying the algorithm to the AMSR-E.
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  • Tomohito YAMADA, Shinjiro KANAE, Taikan OKI
    2004 Volume 48 Pages 223-228
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The extent of the coupling strength between the land and the atmosphere controls the behavior of the atmospheric processes. Precipitation is induced by the soil moisture variation. K02 focused on the coupling strength between four AGCMs. It is mentioned that the coupling strength has much model dependence. The authors are participating the GLACE (Global Land-Atmosphere Coupling Experiment) which follows the K02 experiment. Before undertaking the GLACE experiment, it is conducted the K02 experiment to compare or evaluate our AGCM (CCSR/NIES) result with K02 results. As a result, the coupling strength on the precipitation process is much weaker than the latent heat flux. This is the same characteristics in three of four models in other K02 participants. Moreover, the coupling strength on the latent heat flux shows the relatively high value over the Central Eurasia or the North America.
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  • Kei YOSHIMURA, Masahiro KOIKE, Taikan OKI, Nobuhito OHTE
    2004 Volume 48 Pages 229-234
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Stable water isotopes (D and 18O) in river water, which have integrated information of land surface processes, have been firstly reproduced by an isotopic land surface model (IsoLSM) and an isotopic river flow scheme (IsoTRIP) in this paper. Isotopic fractionation by three types of evaporation fromland, i. e. evaporation, transpiration, and evaporation from intercepted water, are incorporated in IsoLSM. Further, a bucket model is assumed for runoff and fractionation calculation.
    Authors suggest the use of river water isotopes for validation of LSMs output related with water transport from an aspect of water quality. Moreover, this study enables us to reasonably estimate variability of isotopic values of evapotranspirated water from land surface. That probably leads better reproduction of spatial and temporal distribution of precipitation isotopes with an atmospheric isotope circulation model.
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  • Masahide ISHIZUKA, Yumi SONE, Hiroyuki II, Tatemasa HIRATA
    2004 Volume 48 Pages 235-240
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    We measured oxygen stable isotope ratios (δ18O) of surface water in Kii Peninsula, and showed their spatial distribution. As a result, the enriched δ18O composition of surface waters were distributed in the southeast area and the depleted δ18O composition of surface waters were distributed in the inland area where the altitude was high (>1000 m). In order to understand the spatial distribution of δ18O composition of surface water, rainfall characteristics were considered as well as topographic effect. We classified the rainfall characteristics with three zones using a ratio of the total number that means how many times precipitation was simultaneously observed between AMeDAS observation stations: 1) the east and southeast area (zone A), 2) the southwest area (zone B), 3) the northwest area (zone C). From the correlation analysis between δ18O and topographic data, we can find that the zoning effects on the topographic effect, especially ina meso-scale area. Our observation result shows that the δ18O composition of surface water was enriched in highprecipitation area. This result does not correspond to the isotopic amount effect. We think this reasons that continuous vapor supply from the sea keeps δ18O composition of rain clouds enriched.
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  • Sadataka SHIBA, Yushi HIRATA, Shunsaku YAGI
    2004 Volume 48 Pages 241-246
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    Taking account of the variation of the water vapor content and the temperature in the air parcel, a new model for the size estimation of the cloud droplets on multi-sized CCN has been developed by modifying traditional Kohler model for the equilibrium state. The modification of Kohler model is based on the mass and the heat conservation laws applied for the control volume of multi-sized CCN. Variations of droplet size, decrement of saturation ratio and increment of temperature with CCN composition (size and number) of air parcel are simulated numerically. The results of numerical simulations with this new model show that competitive growth of droplets on multi-sized CCN is controlled by large size CCN.
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  • Hiroyuki TSUTSUI, Toshio KOIKE, Katsunori TAMAGAWA, Hideyuki HUJII
    2004 Volume 48 Pages 247-252
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In this study, a new algorithm for snow depth and snow grain size is developed based on the microwave radiative transfer theory and validated by using the in-situ snow depth data at the 65 ground-based stations in the northern hemisphere and the Advanced Microwave Scanning Radiometer for the Earth Observation System (AMSRE) on Aqua launched by NASA in 2002. In the cases with the snow depth less than 40cm, the results of validation wre showng ood correspondence of observationv alue and estimationv alue. However, in the case with the snow depth more than 40cm, it is argued that the lower frequenciesh ould be used in the algorithm.
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  • Shinta SETO, Toshio IGUCHI
    2004 Volume 48 Pages 253-258
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    This study challenges identification of precipitation over land by microwave radiometer. For that purpose, we prepare database of land surface brightness temperature from 1998 to 2000 using TRMM (Tropical Rainfall Measuring Mission)/TMI (TRMM Microwave Imager) and PR (Precipitation Radar) data. PR data is used for precise identification of non-rainfall condition. These databases can represent inter-annual variation, seasonal variation, diurnal variation, heterogeneity within 1 degree grid, and variation caused by soil moisture.
    Rainfall identification is done by comparing the deviation of observed brightness temperature from average and standard deviation of referred database with a negative threshold k0. Only 85GHz observation can give comparable result with existing TMI algorithm (2A12) for all rain rate, but 37GHz observation can give as good performance as 85GHz observation in case of strong rainfall (more than 10mm/hour). When diurnal variation or variation by soil wetness is considered, the performance of lower frequency observation is slightly improved.
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  • Tobias GRAF, Toshio KOIKE, Kouichi NISHIMURA
    2004 Volume 48 Pages 259-264
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In this paper a basic study is presented to develop a method to correct solid precipitation data from gauge observations using the passive microwave brightness temperature data and data assimilation.
    Observation and modeling results are indicating a high sensitivity of the 89GHz channel to fresh snow on the ground. The change in the brightness temperature due to snow is used to correct observed solid precipitation data. The old brightness temperature data, the adjusted precipitation and the density of the fresh snow are input parameter for a radiative transfer model. The result is compared with the new brightness temperature and by iteration the precipitation data is adjusted until the modeled value agrees well with the new brightness temperature.
    Good results have been achieved using snow pit data from Sapporo and modeled brightness temperatures. A sensitivity analysis showed, that this cost minimization problem has a unique solution.
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  • Soichiro SUGIMOTO
    2004 Volume 48 Pages 265-270
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The interest of this study is to estimate bias error of operational ground-based radar (GR) data by comparison with coincident data from Precipitation Radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. The methodology of comparison is presented. Three-dimensional distribution of reflectivity factor on the Cartesian grid system is constructed by transformation and interpolation of volume scanning GRdata. The interpolation uses both horizontal and vertical effective radius. The interpolated data yieldsvalues of reflectivity factor at PR-based grid points under the assumption that observations by the TRMM PR are vertical pointing. Such a procedure gives a chance for comparison between data from two separate plathomes. Analysis indicates that the GR used in this study tends to observe less reflectivity factor than the TRMM PR. This tendency is not height-dependent. However, the temporal fluctuation of bias is also found from analysis for 13 rain events occurred during about a year. This is an auxiliary result, which demonstrates the stability of the calibration of the GR system for each short period.
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  • Petra KOUDELOVA, Toshio KOIKE
    2004 Volume 48 Pages 271-276
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    This paper proposes a method for estimating rainfall rate from ground-based radar observations in eastern Tibet. Firstly, the radar reflectivity-rain rate (Z-R) relationship is derived by regression analysis using the hourly data of a single rain gauge located near the radar and the corresponding radar reflectivity over a period of more than two months. Two different relationships are obtained for stratiformand convective rain types. Secondly, an automated convective-stratiform rain classification methodis introduced that uses the horizontal radar echo structure to identify convective regions and classifies the remainder as stratiform areas. The classification algorithm is verified against visual inspections of horizontal and vertical radar echo structures. Finally, the rain rate is estimated from the radar reflectivity for the rain gauge site using the derived Z-R relationships and the rain type information produced by the classification algorithm. The comparison of the estimation and the gauge data suggests good accuracy.
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  • Toshiro KUMAKURA, Norio HAYAKAWA
    2004 Volume 48 Pages 277-282
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The amount of snowcover accumulation in Hokuriku region is not well known over mountaineous area because observing frequency and a number of observatory in the mountaineous area are not enough to obtain necessary data. We attempt to simulate for predicting the snowfall intensity over the whole area with a meteorological numerical simulation model. We found that the simulated snowfall intensity under-estimates the observed intensity although the horizontal patterns of snowfall area and cloud-generating area are simulated well. We also found that realistic values of the roughness length and the albedo at the ground surface play important roles to obtain the accurate horizontal distribution of snowfall under a winter monsoon at Hokuriku region.
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  • Shuichi SATO, Satoru OISHI, Kengo SUNADA, Makoto AKAIKE
    2004 Volume 48 Pages 283-288
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    In this study, we investigate the effect of the topography about torrential rain in several areas. In this research, several numerical simulation was made by using Nonhydrostatic Model that Numerical Prediction Division and Meteorological Research Institute have developed. We chose three areas which are Tokai area, Kanto area and the area of north part of the Lake Biwa. Comparison among the effect of above mentioned three topographies on the atmospheric circumstance of torrential rain in the Tokai area was investigated by numerical simulation.
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  • Yoshiharu SUZUKI, Shohei MIYATA, Eiichi NAKAKITA, Shuichi IKEBUCHI
    2004 Volume 48 Pages 289-294
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The purpose of this research is to analyze rainfall-topography relationships and determine their physical mechanism by running numerical simulations under ideal conditions using mesoscale model MM5. The model was set up including an isolated mountain with a triangular section as the ideal topography. The relation between topographic elevation and simulated rainfall amount was investigated using the stratified sampling method. As a result, it was found that the rainfall-topography relationships on an isolated mountain can be described with a Gaussian-type function, and their mechanism was clarified by investigating the development process of convective cells. It was also determined how the parameters of the function vary with topographic conditions and horizontal speed of the prevailing wind.
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  • Assela PATHIRANA, Tadashi YAMADA
    2004 Volume 48 Pages 295-300
    Published: February 01, 2004
    Released on J-STAGE: June 04, 2010
    JOURNAL FREE ACCESS
    The impact of different atmospheric and topographic conditions on the rainfall distribution around a single, infinitely long ridge is investigated. The main objective of the study was to understand the conditions that are responsible for commonly observed rainfall patterns like high rainfall yields on the side of the ridge facing the wind and rain-shadows on the lee side. A modified version of MM5, a non-hydrostaticmodel that is widely used for limited area atmospheric simulations for research and operational purposes, was used for this study. The effects of different mountain ridge dimensions, large-scale wind conditions and large-scale moisture profiles on the amount and distribution of orographic precipitation, were clarified. Ridge height has a positive correlation with the amount of rainfall generated while the ridge width did notshow such a clear relationship. Slowing of wind speed resulted in the spreading of rainfall outwards from the mountain peak. Reduction of moisture caused a reduced rainfall yield. Most of the simulations produced highest rainfall amounts on the windward slopes. However, changing the topography, wind speed or moisture, a rain shadow condition could not be attained. The introduction of a reversal of the winds in the upper atmosphere as observed in Asian summer monsoon and many other large-scale atmospheric flows onthe globe, created a rain shadow by confining the rainfall completely to the upstream of the ridge top.
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