scholarly journals Analysis of Salinity Behavior in Hakata Bay after Heavy Rainfall Using a Three-dimensional σ-Coordinate Model

2021 ◽  
Vol 55 (2) ◽  
pp. 137-146
Author(s):  
Akihiro FUKUDA ◽  
Toshinori TABATA ◽  
Kazuaki HIRAMATSU ◽  
Masayoshi HARADA
Keyword(s):  
Heavy Rainfall ◽  
Three Dimensional ◽  
Coordinate Model

SIMULATION AND EARLY WARNING OF NATURAL AND TECHNOGENIC INFLUENCES IN COASTAL AREAS IN THE SEA OF AZOV

2017 ◽  
Author(s):  
Tatiana Shulga ◽  
Tatiana Shulga ◽  
Leonid Cherkesov ◽  
Leonid Cherkesov
Keyword(s):  
Model Comparison ◽  
Three Dimensional ◽  
Storm Surges ◽  
Ecological Condition ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
Waves And Currents ◽  
Coordinate Model ◽  
Passive Admixture ◽  
Comparison Of The Results

In this work, the waves and currents generated by prognostic wind in the Sea of Azov are investigated using a three-dimensional nonlinear sigma-coordinate model. The mathematical model was also used for studying the transformation of passive admixture in the Sea of Azov, caused by the spatiotemporal variations in the fields of wind and atmospheric pressure, obtained from the prediction SKIRON model. Comparison of the results of numerical calculations and the data of field observations, obtained during the action of the wind on a number of hydrological stations was carried out. The evolutions of storm surges, velocities of currents and the characteristics of the pollution region at different levels of intensity of prognostic wind and stationary currents were found. The results of a comprehensive study allow reliably estimate modern ecological condition of offshore zones, develop predictive models of catastrophic water events and make science-based solutions to minimize the possible damage.

scholarly journals Three-dimensional observations of heavy rainfall using a phased-array weather radar

2014 ◽  
Vol 34 (135) ◽  
pp. 4-9
Author(s):  
Fusako ISODA ◽  
Shinsuke SATOH ◽  
Hiroshi HANADO ◽  
Nobuhiro TAKAHASHI ◽  
Fumihiko MIZUTANI ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Phased Array ◽  
Three Dimensional ◽  
Weather Radar

Gas Turbine Engine Test Cell Modeling

1990 ◽  
Author(s):  
D. Salinas ◽  
E. E. Cooper
Keyword(s):  
Kinetic Energy ◽  
Gas Turbine ◽  
Three Dimensional ◽  
Gas Turbine Engine ◽  
Test Cell ◽  
Dimensional System ◽  
Engine Test ◽  
Turbine Engine ◽  
Coordinate Model ◽  
Cartesian Coordinate

A numerical simulation of the aerothermal characteristics of a gas turbine engine test cell is presented. The three-dimensional system is modeled using the PHOENICS computational fluid dynamics code. Results predict the velocity field, temperatures, pressures, kinetic energy of turbulence, and dissipation rates of turbulent kinetic energy. Numerical results from two versions, a cartesian coordinate model and a body fitted coordinate model, are compared to experimental data. The comparison shows good quantitative and very good qualitative agreement, suggesting that numerical modeling would be useful in the preliminary design of gas turbine test facilities.

scholarly journals A Comparative Study on Performance of Analysis Nudging and 3DVAR in Simulation of a Heavy Rainfall Event Using WRF Modeling System

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Ashish Routray ◽  
Krishna K. Osuri ◽  
Makarand A. Kulkarni
Keyword(s):  
Data Assimilation ◽  
Heavy Rainfall ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Rainfall Event ◽  
Initial Time ◽  
Heavy Rainfall Event ◽  
Synoptic Features ◽  
Wrf Modeling ◽  
Data Assimilation Technique

The present study focuses on the performance-based comparison of simulations carried out using nudging (NUD) technique and three-dimensional variational (3DVAR) data assimilation system (3DV) of a heavy rainfall event occurred during 25–28 June 2005 along the west coast of India. The Indian conventional and nonconventional observations are used in the 3DV experiment. Three numerical experiments are conducted using WRF modeling system, the model is integrated upto 54 hours from the initial time 0000 UTC of 25 June 2005. It is noticed that the meteorological parameters are improved in the resulting high-resolution analyses prepared by NUD and 3DV compared to without data assimilation experiment (i.e., called CNTL experiment). However, after the successful inclusion of observations using the 3DVAR data assimilation technique, the model is able to simulate better structure of the convective organization as well as prominent synoptic features associated with the mid-tropospheric cyclones (MTC) than the NUD experiment and well correlated with the observations. The simulated location and intensity of rainfall is also improved in 3DV simulation as compared with other experiments. Similar results are noticed in the root mean squar errors, correlation coefficients, and Equitable Threat Scores between TRMM and model simulated rainfall for all the three experiments.

scholarly journals Three-Dimensional Circulation Structure of Summer Heavy Rainfall in Central North China

2015 ◽  
Vol 30 (1) ◽  
pp. 238-250 ◽  
Author(s):  
Wei Sun ◽  
Rucong Yu ◽  
Jian Li ◽  
Weihua Yuan
Keyword(s):  
Heavy Rainfall ◽  
North China ◽  
Three Dimensional ◽  
Lower Troposphere ◽  
Northern China ◽  
Front Side ◽  
The North ◽  
Westerly Jet ◽  
High Level ◽  
Circulation Structure

Abstract Based on daily rainfall observations and Japanese 25-year Reanalysis Project data during ~1981–2010, a three-dimensional circulation structure that formed before heavy summer rainfall in central north China (CNC) is revealed in this study. Composite analyses of circulation in advance of 225 heavy rain days show that the circulation structure is characterized by a remarkable upper-tropospheric warm anomaly (UTWA), which covers most of northern China with a center at ~300 hPa. Under hydrostatic and geostrophic equilibriums, the UTWA contributes to the generation of an anticyclonic (cyclonic) anomaly above (below). The anticyclonic anomaly strengthens (weakens) westerly winds to the north (south) of the warm center and pushes the high-level westerly jet to the north. The cyclonic anomaly deepens the trough upstream of CNC and intensifies lower southwesterly winds to the mideast of the warm center. As a result, the northerly stretched high-level jet produces upper divergence in its right-front side and the intensified southwesterly winds induce lower moisture convergence in its left-front side, causing heavy rainfall in CNC. Correlation analyses further confirm the close connections between UTWA and circulation in the upper and lower troposphere. The correlation coefficients between UTWA and the upper geopotential height, upper westerly jet, and lower southerly flow reach 0.95, 0.70, and 0.39, implying that the two critical factors leading to intense rainfall in CNC, the high-level jet and the low-level southerly flow, are closely connected with the UTWA. Consequently, in the future analyses and forecasts of heavy rainfall over northern China, more attention should be paid to the temperature in the upper troposphere.

A Supercell Storm Simulation Using a Nonhydrostatic Cloud-Resolving Model Based on a Hybrid Isentropic-Sigma Vertical Coordinate

2013 ◽  
Vol 141 (4) ◽  
pp. 1204-1215 ◽  
Author(s):  
Michael D. Toy
Keyword(s):  
Mass Flux ◽  
Potential Temperature ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Implicit Time ◽  
Vertical Coordinate ◽  
Model Based ◽  
Supercell Storm ◽  
Coordinate Model ◽  
Isentropic Coordinates

Abstract A three-dimensional simulation of a supercell storm is performed with a nonhydrostatic model based on a hybrid isentropic-sigma vertical coordinate. The coordinate is a terrain-following, height-based coordinate near the surface that smoothly transitions to potential temperature with height. Using isentropic coordinates provides the advantage of having zero cross-coordinate vertical mass flux for adiabatic flow, which virtually eliminates the numerical error in the vertical transport. The model uses an adaptive grid algorithm by which the coordinate surfaces may deviate from their target isentropes to maintain a sufficiently smooth mesh, while allowing the turbulence and vertical motion associated with convection to develop. The storm simulated by the hybrid-coordinate model compares well with simulations by Eulerian-coordinate models, but with the key difference being that the cross-coordinate mass flux is significantly smaller in much of the domain with the hybrid-coordinate model. A semi-implicit time-differencing scheme for numerically stabilizing vertically propagating acoustic modes in isentropic coordinates is also presented in the paper.

scholarly journals Impact of radar data assimilation using WRF three-dimensional variational system, for the simulation of a heavy rainfall case in Central Italy

2013 ◽  
Vol 6 (4) ◽  
pp. 7315-7353
Author(s):  
I. Maiello ◽  
R. Ferretti ◽  
S. Gentile ◽  
M. Montopoli ◽  
E. Picciotti ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Radial Velocity ◽  
Heavy Rainfall ◽  
Initial Conditions ◽  
Positive Impact ◽  
Central Italy ◽  
Three Dimensional ◽  
Warm Start ◽  
The Impact ◽  
Dwr Data

Abstract. This work is a first assessment of the role of Doppler Weather radar (DWR) data in a mesoscale model for the prediction of a heavy rainfall. The study analyzes the event occurred during 19–22 May 2008 in the urban area of Rome. The impact of the radar reflectivity and radial velocity acquired from Monte Midia Doppler radar, on the assimilation into the Weather Research Forecasting (WRF) model version 3.2, is discussed. The goal is to improve the WRF high resolution initial condition by assimilating DWR data and using ECMWF analyses as First Guess thus improving the forecast of surface rainfall. Several experiments are performed using different set of Initial Conditions (ECMWF analyses and warm start or cycling) and a different assimilation strategy (3 h-data assimilation cycle). In addition, 3DVAR (three-dimensional variational) sensitivity tests to outer loops are performed for each of the previous experiment to include the non-linearity in the observation operators. In order to identify the best ICs, statistical indicators such as forecast accuracy, frequency bias, false alarm rate and equitable threat score for the accumulated precipitation are used. The results show that the assimilation of DWR data has a positive impact on the prediction of the heavy rainfall of this event, both assimilating reflectivity and radial velocity, together with conventional observations. Finally, warm start results in more accurate experiments as well as the outer loops strategy.

scholarly journals Transport Variability of the Brazil Current from Observations and a Model

2017 ◽  
Author(s):  
Claudia Schmid ◽  
Sudip Majumder
Keyword(s):  
Interannual Variability ◽  
Three Dimensional ◽  
Austral Summer ◽  
Southern Annular Mode ◽  
South Atlantic ◽  
Meridional Transport ◽  
Sea Level Pressure ◽  
Brazil Current ◽  
Coordinate Model ◽  
The Impact

Abstract. Brazil Current transports from observations and a model are analyzed to improve our understanding of its structure and variability. The observed transports are derived from a three-dimensional field of the velocity in the South Atlantic covering the years 1993 to 2015 (hereinafter called Argo & SSH). The mean transport of the Brazil Current from 3.8 ± 2.2 Sv (1 Sv is 106 m3s−1) at 25° S to 13.9 ± 2.6 Sv at 32° S, which corresponds to a mean slope of 1.4 ± 0.4 Sv per degree. The Hybrid Coordinate Model (HYCOM) has somewhat higher transports than Argo & SSH (5.2 ± 2.7 Sv and 18.7 ± 7.1 Sv at 25° S and 32° S), but these differences are small when compared with the standard deviations. Overall, the observed latitude dependence of the transport of the Brazil Current is in agreement with the wind-driven circulation in the super gyre of the subtropical South Atlantic. A mean annual cycle with highest (lowest) transports in austral summer (winter) is found to exist at selected latitudes (24° S, 35° S and 38° S). The significance of this signal shrinks with increasing latitude, mainly due to the mesoscale and interannual variability. In addition, it is found that the interannual variability at 24° S is correlated with the Southern Annular Mode and the Niño 3.4 index. A coupled EOF of the meridional transport and the sea level pressure is used to improve the understanding of the impact of these ocean indexes.

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