| 44 | | = The THREDDS Data Server = #s.thredds |
| 45 | | |
| 46 | | The ''SPECS-EUPORIAS Data Portal'' is based on a password-protected `THREDDS data server` (`TDS`) providing metadata and data access to a set of georeferenced atmospheric variables using OPeNDAP and other remote data access protocols. The variables names, units and additional metadata follow the [http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html CF convention]. The variables are spatial grids based on multidimensional arrays of indexed values, following Unidata's ''_Coordinate convention''[[FootNote(http://www.unidata.ucar.edu/software/netcdf-java/reference/CoordinateAttributes.html)]][[FootNote(http://www.unidata.ucar.edu/software/netcdf-java/tutorial/GridDatatype.html)]]. |
| 47 | | |
| 48 | | Typically the data portal will include information at a daily resolution, but monthly-aggregated values could be also provided in some cases due to data limitations (in particular, ''Mètèo-France'' and ''Met Office'' have agreeed to provide monthly mean hindcasts for their use by the ''SPECS'' and ''EUPORIAS'' partners). In general, the data available will be typical surface variables (e.g. precipitation and near-surface temperature), although several variables (e.g. geopotential and temperature) on pressure levels will also be stored for the statistical downscaling activities. |
| 49 | | |
| 50 | | The data gathering activities have initially focused on the ''ECMWF System4 seasonal model''. The Meteorological Archival and Retrieval System (`MARS`) is the main repository of meteorological data at the ''ECMWF'' (European Centre for Medium-Range Weather Forecasts). It contains terabytes of operational and research data as well as data from special projects[[FootNote(http://www.ecmwf.int/services/archive/)]]. The large amount of information stored and the inherent complexities of data access, download and post-processing is a first shortcoming for a flexible use of these datasets by a large number of partners. To overcome this issue, a reduced subset of surface variables[[FootNote(http://www.ecmwf.int/products/changes/system4/technical_description.html#description)]] (precipitation, temperatures and mean sea level pressure) have been downloaded from `MARS` (a colection of `GRIB-1` files) at 0.75º spatial resolution and made available throught the ''SPECS-EUPORIAS data portal''. The downloaded data has been exposed as three different virtual datasets using `TDS`: |
| 51 | | |
| 52 | | * '''System4 seasonal range (15 members)''': There are twelve initializations (hereafter called `runtimes`) per year (the first of January, February, ...) running for 7 months (hereafter called simply `times`). An ensemble of 15 members is available for the whole 1981-2010 period. |
| 53 | | * '''System4 seasonal range (51 members)''': There are only four `runtimes` per year (the first of February, May, August and November) and the forecasts run for 7 months. An ensemble of 51 members is available for the whole 1981-2010 period. |
| 54 | | * '''System4 annual range (15 members)''': As in the previous case, there are four `runtimes` per year, but the forecasts run for 13 months. An ensemble of 15 members is available for the whole 1981-2010 period. |
| 55 | | |
| 56 | | Data gathering activities will next move to the CFS (http://cfs.ncep.noaa.gov) version 2 hindcast, developed at the ''Environmental Modeling Center at NCEP'' and also to reanalysis and observational datasets. |
| 59 | | = Accesing the Data Portal via `R` = #s.r.access |
| 60 | | |
| 61 | | = Accesing the Data Portal via Web = #s.web.access |
| 62 | | |
| 63 | | |
| 64 | | |
| 65 | | |
| 66 | | = Accessing to the Data portal using Octave = #ex.octave |
| 67 | | |
| 68 | | [[NoteBox(warn,This section needs revision and integrtion with the [#ex.matlab Matlab example section])]] |
| 69 | | |
| 70 | | {{{#!text/matlab |
| 71 | | >> ver |
| 72 | | ---------------------------------------------------------------------- |
| 73 | | GNU Octave Version 3.6.1 |
| 74 | | GNU Octave License: GNU General Public License |
| 75 | | Operating System: unknown |
| 76 | | ---------------------------------------------------------------------- |
| 77 | | }}} |
| 78 | | |
| 79 | | {{{#!text/matlab |
| 80 | | >> urlwrite('http://www.meteo.unican.es/work/netcdfAll-4.3.jar','netcdfAll-4.3.jar') |
| 81 | | >> javaaddpath('./netcdfAll-4.3.jar'); |
| 82 | | >> javaMethod('setGlobalCredentialsProvider','ucar.nc2.util.net.HTTPSession',javaObject('ucar.nc2.util.net.HTTPBasicProvider','username','password')); |
| 83 | | >> ncfile = javaMethod('openDataset','ucar.nc2.dataset.NetcdfDataset','http://www.meteo.unican.es/tds5/dodsC/system4/System4_Seasonal_15Members.ncml'); |
| 84 | | >> v = ncfile.findVariable('Minimum_temperature_at_2_metres_since_last_24_hours_surface'); |
| 85 | | >> disp(v.getDimensions.toString) |
| 86 | | [ member = 15;, run = 360;, time = 215;, lat = 241;, lon = 480;] |
| 87 | | >> d = v.read('0,11:359:12,31:61,66,475'); |
| 88 | | >> tmp = javaObject('org.octave.Matrix',d.reduce.copyToNDJavaArray); |
| 89 | | >> oldFlag = java_convert_matrix (1); |
| 90 | | >> octaveMatrix = tmp.ident(tmp); |
| 91 | | [ (30 by 31) array of double ] |
| 92 | | >> disp(squeeze(mean(octaveMatrix,2))') |
| 93 | | Columns 1 through 13: |
| 94 | | |
| 95 | | 270.79 273.29 271.57 271.04 271.83 272.49 271.48 268.59 271.53 273.82 270.99 274.24 270.99 |
| 96 | | |
| 97 | | Columns 14 through 26: |
| 98 | | |
| 99 | | 271.56 273.99 270.51 272.45 270.66 271.31 272.77 273.44 271.85 273.40 274.16 269.98 271.30 |
| 100 | | |
| 101 | | Columns 27 through 30: |
| 102 | | |
| 103 | | 273.12 271.27 272.29 270.47 |
| 104 | | }}} |
| 105 | | |
| 106 | | = Accessing to the Data portal using Matlab= #ex.matlab |
| 107 | | |
| 108 | | [[NoteBox(warn,This section needs revision])]] |
| 109 | | |
| 110 | | {{{#!text/matlab |
| 111 | | >> ver |
| 112 | | ------------------------------------------------------------------------------------- |
| 113 | | MATLAB Version 7.8.0.347 (R2009a) |
| 114 | | MATLAB License Number: 161051 |
| 115 | | Operating System: Microsoft Windows Vista Version 6.1 (Build 7601: Service Pack 1) |
| 116 | | Java VM Version: Java 1.6.0_04-b12 with Sun Microsystems Inc. Java HotSpot(TM) 64-Bit Server VM mixed mode |
| 117 | | ------------------------------------------------------------------------------------- |
| 118 | | >> javaaddpath('http://www.meteo.unican.es/work/netcdfAll-4.3.jar'); |
| 119 | | >> %javaaddpath('ftp://ftp.unidata.ucar.edu/pub/netcdf-java/v4.3/netcdfAll-4.3.jar'); |
| 120 | | }}} |
| 121 | | |
| 122 | | {{{#!text/matlab |
| 123 | | >> import ucar.nc2.util.net.* %this will download the netcdfAll-4.3.jar |
| 124 | | >> HTTPSession.setGlobalCredentialsProvider(HTTPBasicProvider('username','password')); |
| 125 | | >> import ucar.nc2.*; |
| 126 | | >> import ucar.nc2.dataset.*; |
| 127 | | >> ncfile = NetcdfDataset.openDataset('http://www.meteo.unican.es/tds5/dodsC/system4/System4_Seasonal_15Members.ncml'); |
| 128 | | >> v = ncfile.findVariable('Minimum_temperature_at_2_metres_since_last_24_hours_surface'); |
| 129 | | >> disp(v.getDimensions) |
| 130 | | [ member = 15;, run = 360;, time = 215;, lat = 241;, lon = 480;] |
| 131 | | >> data = v.read('0,11:359:12,31:61,66,475').copyToNDJavaArray(); |
| 132 | | >> disp(squeeze(mean(data,3))) |
| 133 | | Columns 1 through 13 |
| 134 | | |
| 135 | | 270.7917 273.2944 271.5666 271.0371 271.8275 272.4928 271.4809 268.5912 271.5313 273.8216 270.9940 274.2363 270.9933 |
| 136 | | |
| 137 | | Columns 14 through 26 |
| 138 | | |
| 139 | | 271.5612 273.9899 270.5076 272.4505 270.6556 271.3118 272.7720 273.4359 271.8502 273.3965 274.1638 269.9825 271.3017 |
| 140 | | |
| 141 | | Columns 27 through 30 |
| 142 | | |
| 143 | | 273.1195 271.2730 272.2915 270.4669 |
| 144 | | }}} |
