7/27/2019 Development of a software

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Robert ToderascuDunarea de Jos University, Faculty of Mechanical Engineering, Galati, Romania

AbstractOn November 12, 2007 a fierce accident occurred in the Black Sea when Volga-Neft tanker, carrying 4,000 tons of crude oil, broke in two during a storm, when it wasperforming a stopover in the Russian port Kavkaz. The officials reported on this incident as a very serious environmental disaster. It spilled at least 1,300 tons of oil. Thesevere weather prevented emergency workers from collecting the oil, which authorities said was sinking to the seabed. Hours after Russian oil tanker incident, two othercargo ships carrying sulfur sank near the port Kavkaz. The increasing traffic on the BlackSeas surface rises considerably the risks of accidents like the above mentionedone. In order to avoid or minimize potential accidents its impossible not to observe the necessity of implementing an operational numerical model in order to prevent and

minimize the damage to the Black Sea. This work refers to the development of a software for processing data related with MOHID (Water Modeling Software) model, inorder to asses currents speed and directions for the Black Sea basin.

2. SolutionHDF5 is a data model, library, and file format for storing and managing data. It supports anunlimited variety of datatypes, and is designed for flexible and efficient I/O and for highvolume and complex data. HDF5 is portable and is extensible, allowing applications toevolve in their use of HDF5. The required HDF5 file format for MOHID will have tocontain 3 groups: Grid, Results and Time. The grid group will include the following datasets: Bathymetry, Connection X, Connection Y, Latitude, Longitude, Vertical Z and WaterPoints.Bathymetry dataset stores the depths of the sea. The file is downloaded from Etopo websitewith a resolution of ~ 1.8 km, then transform with Geodas program to display the depthswith positive values and the heights with negative. Next the data is loaded into MOHID GIS

(a geographical information system designed to support MOHID). The coastlines will haveto be either drawn using Google earth or directly in MOHID GIS if possible. The horizontalgrid will be set according to the desired resolution (in this case it has been chosen the sameresolution as the temperature and salinity data 238x132, in order to avoid errors). TheMOHID Digital Terrain creator will be next run in order to produce the Bathymetry data forthe HDF5 file, as well as for the actual simulation with MOHID (figure 2). Latitude andLongitude data will be interpolated in Matlab to correspond to exact latitude and longitudeof the temperature and salinity data. Connection X and Connection Y will be transformedfrom latitude and longitude data, since the refer to UTM coordinates (however they are notmandatory). Vertical Z dataset is formed from the assumed depth plus one more for thesurface which will have to be zero. Water Points will tell MOHID if a given point is to berepresented or no, so for every point inside the data that has a value will be equal to 1 andfor every land points will be 0. Water Points will be a matrix of 238x132x35. Results groupwill contain the initial temperature or salinity values as well as the ones computed byMOHID after the simulation, for every time step of the simulation. And Time group willcontain all the time steps for which the simulation will run, in our case 31 days, for themonth of January 2010. In order to maintain a small data size we chose to make separatescripts for temperature and salinity. Aside from the different results groups there is no other

difference among them. After the HDF5 files has been created it is needed to pass the filetrough an HDF5 executable which will check for possible errors and perform a level 6 GZIParchiving, since MOHID will not read any other format. Once the GZIP archiving isfinished, the HDF5 file is ready to be introduced in MOHIG GIU and used for analysis. Ascheme of the described processes is presented above in figure 1, figure 3 showing theinspection of certain depth levels of the resulted temperature file: a) level 1, b) level 3, c)level 7, d) level 11, e) level 15, f) level 19, g) level 23, h) level 27 and i) level 35.

1. IntroductionMOHID is a three-dimensional water modeling system developed by MARETEC (Marine andEnvironmental Technology Research Center) at the Technical University of Lisbon.This system allows for the adoption of an integrated modeling philosophy, not only of processes,but also of different scales (allowing the use of nested models) and systems (estuaries andwatersheds), due to the adoption of an object oriented programming philosophy. The integrationof MOHID different tools, (MOHID Water, MOHID Land and MOHID Soil) can be used tostudy the water cycle in an integrated approach. Since these tools are based on the sameframework, their coupling can be easily achieved. Currently, MOHID is under implementationfor the Black Sea basin. The purpose of this work is to focus on the development of anoperational software able to process temperature and salinity data in the format needed forMOHID input.

3. Future development directions and problems metThis example has been made using the original grid level from temperature and salinity data(238x132x35) but the matrixes can be interpolated or extrapolated to fit any desired area. Thismethod will be used for level 2, 3 and 4 generation towards the Romanian coasts, once the firstsimulation is finished. The work at the processing software is still in progress since is enough forone single point or quote to be misplaced and the MOHID simulation will crash. Anotherproblem met was the different formats used for HDF5 files, since MOHID uses HDF5 libraryversion 1.6.4 and Matlab 2009b uses 1.8 library versions. Downgrading the HDF5 library forMatlab is impossible, so the only valid solution was to recompile a MOHID executable file inorder to include newer HDF5 libraries. For future improvements we are considering includingwind and wave data, as well as minimizing the scripting code size by using iteration methods,since its currently around 100 pages for one month. At the end this software will be part of anintegrated system which will include MOHID for water circulation and SWAN for wavegeneration in order to be able to predict and asses oils spill movement for the Black Sea basin.

MyOceanwebsite

Etopowebsite

MOHID GIS

MATLAB

HDF5repack

MOHID

GUI

MOHID Digital Terrain

2. Formulation of the problemBlack Sea being and enclosed sea, tides are extremely small and dont interfere with currentcirculation. In order to force current movement for the Black Sea basin there is need fortemperature and salinity data. MOHID can accept input only from HDF5(Hierarchical data file)data type, and the temperature and salinity data can be found in various datasets over the interneton specialized websites. In this case a request has been performed on the MyOcean website andaccess to BLACKSEA_ANALYSIS_FORECAST_PHYS_007_001 data has been granted. Thiskind of data contains temperature, salinity, depth and time archived in a NETCDF CF 1.4 format.The temperature and salinity are produced on a regular grid of 238x132x35 grid points (~5 kmhorizontal resolution), depth being on 35 levels that vary from 5 to 5 meters close to surface and100 meters close to the bottom layer. Inside one file there are data for 6 time intervals, eachcorresponding to one day. These data needs to be transformed and coupled with bathymetry,latitude and longitude files for MOHID required input and written in an HDF5 file. For datamanipulation and transformation, Matlab 2009b has been used.

5. References1. Booij, N. Ris, R. C and Holthuijsen, L. H., 1999. A third generation wave model for coastal regions. Part 1: Model description and

validation,J. Geophys. Res. 104, C4, pp. 7649-7666.2. INSTITUTO SUPERIOR TCNICOMARETEC, MOHID Hydrodynamic Module User Guide3. A. Svendsen, Kevin Haas, and Qun Zhao, Center for Applied Coastal Research University of Delaware, Quasi-3D NearshoreCirculation Model SHORECIRC4. E. Rusu, F. Onea, R. Toderascu, Galati University Dunarea de Jos, Romania, Dynamics of the Environmental Matrix in the Black Seaas Reflected by Recent Measurements and Simulations with Numerical Models, Nova Publishers, 20105. Rusu, E, 2010: Modeling of wave-current interactions at the Danube s mouths, Journal of Marine Science and Technology article in

press. http://www.springerlink.com/content/pqq215x867882424/

Figure 1. Logical scheme of the proposed system

Figure 3. Resulted temperature file on different depth levels: a) level 1, b) level 3, c) level 7,d) level 11, e) level 15, f) level 19, g) level 23, h) level 27 and i) level 35.

a) b) c)

d) e) f)

g) h) i)

Figure 2. The Black Seas resulted bathymetry after the run of MOHID Digital Terrain creator.

http://www.springerlink.com/content/pqq215x867882424/http://www.springerlink.com/content/pqq215x867882424/