Seasonal data fields for the Mediterranean Sea




Summer surface salinity field constructed on a 167x63 grid.
From 34.7 psu (blue) to 39.8 psu (red).


Table of Contents





1. Introduction

This page provides access to the Mediterranean seasonal climatology reconstructed from a historical hydrological data base. The resulting 3D fields (salinity, temperature and velocity) are stored as 3D matrices, with description of the grid location. A direct access to these fields and a description of the file format are also provided in this page.

If you prefer to load the files manually, please use the ftp server instead.

If there is any problem with this data set (reading, importing, ...) please contact the MODB support (support@modb.oce.ulg.ac.be).

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2. Two different data sets

We provide two versions of this seasonal gridded data set (MED2 and MED4). They differ by the data base that has been used to build them. Both data sets are accessible in the last part of this page by clicking on the convenient (MED2 or MED4) button.

-A- THE MED2 DATA SET (RELEASED APRIL 01, 1994)

The MED2 Gridded Data Set is the result of the application of the VIM analysis method (1) on a historical data bank resulting from the merging of two main files:

A full description of this data set, the analysis technique and the results obtained at the seasonal time scale is available in (2). The printed version of an atlas (3) can be ordered by sending an e-mail to support@modb.oce.ulg.ac.be.
  1. Brasseur P., 1991, A Variational Inverse Method for the reconstruction of General Circulation Fields in the Northern Bering Sea, J. Geophys. Res., 96(C3), 4891-4907.
  2. Brasseur P., Beckers J.M., Brankart J.M. and Schoenauen R., 1995, Seasonal Temperature and Salinity Fields in the Mediterranean Sea: Climatological Analyses of a Historical Data Set.
  3. Brasseur P., Brankart J.M., Beckers J.M., 1994, Seasonal Variability of the General Circulation of the Mediterranean : results of climatological analyses. (B/W)

-B- THE MED4 DATA SET (RELEASED APRIL 24, 1995)

The MED4 Gridded Data Set has been computed using the first released MODB data base which differs from the previous one mainly by the addition of the bathythermographs from the U.S. NODC world ocean data bank.

THIS ANALYSIS IS STILL IN PROGRESS. IT SHOULD BE CONSIDERED VERY CAUTIOUSLY MAINLY BECAUSE THE FULL QUALITY CHECK OF THE BANK IS NOT FINISHED YET.

The fields might consequently exhibit some unrealistic patterns. Nevertheless, we think that they contain interesting new features (especially the velocity fields). It is the reason why we decide to make them publicly available.

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3. Analysed Data Fields

There are four seasons for the data set :

  1. WINTER : January, February, March
  2. SPRING : April, May, June
  3. SUMMER : July, August, September
  4. AUTUMN : October, November, December

There are four files for each season :

  1. SALINITY,
  2. TEMPERATURE,
  3. U HORIZONTAL (GEOSTROPHIC) VELOCITY,
  4. V HORIZONTAL (GEOSTROPHIC) VELOCITY.

Units are 0/00 for salinity, degree Celsius for temperature and m/s for velocity.

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4. Matrix description

To understand the way the data is stored, please refer to the figure below. The file are stored in a 3D array (matrix) with 3 indexes I, J, K, going from 1 to IMAX, 1 to JMAX, 1 to KMAX. The origin is located at the 'bottom left deepest corner'.



There are KMAX horizontal slices from the bottom (K=1) to the surface (K=KMAX). Increasing I's go from W to E and increasing J's go from S to N.

Islands, coasts and places where there are no values are represented by an exclusion value.

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5. Localisation

The point (i,j,k) is located at (-5.5 + i*0.25 , i=1,167) long and (30.0 + j*0.25 , j=1,63) lat at a depth given by the Kth line of the file MED2.zed or MED4.zed .

Example :
The point (3,4,1) is located at -4.75 long and 31.0 lat at -5m under the sea surface.

Warning
The grid of the MED4 climatology is temporarily extended westwards.
The point (i,j,k) is located at (-9.5 + i*0.25, i=1,184) lon and (30.0 + j*0.25, j=1,63 ) lat
Depth is given by the kth line of the file MED4.zed.
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6. Reading the data

The data sets are stored in compressed ASCII files. First you must 'uncompress' the files with the Unix command 'uncompress'. The size of your file will increase to about 4.3 MB.

The first line of the ASCII file contains the dimension of the array : IMAX, JMAX, KMAX. The integers are stored with the FORTRAN format I5.

The second line contains the exclusion value, the minimum and the maximum value of this file. These numbers are stored with the FORTRAN format E12.5.

The remaining lines contains the data of the array, with 5 numbers per line (except the last line for each I-line).

The array is stored in horizontal slices from sea surface to sea bottom and from north to south. So the indexes go from :


   DO K = KMAX to 1
       DO J = JMAX to 1
           DO I = 1 to IMAX
              read
           OD
       OD
   OD

There are two examples of extracting routines written in FORTRAN :

readata1.f , readata2.f

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7. Access to the Data Fields

Here is the list of the available matrices :

  1. Winter

  2. Spring

  3. Summer

  4. Automn

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Last modified December 8, 1995
Send comments to support@modb.oce.ulg.ac.be