View source for SWAN GIS Getting Input Data

=Introduction=
This page guides you through the process of obtaining the bathymetric, wind and wave data required to develop our wave model. It is the second component of our SWAN GIS Tools [[SWAN_GIS_Tools#Step_by_Step_Guide |step by step guide]].<br>

''Please note this data is already included in the tutorial download '''Complete_Model\DATA''' folder, so if you want to this section can be optionally skipped. We do, however, highly recommend working through this process as you will likely need to complete these steps when you start to build your own project.'' <br>

=Bathymetry Data=
The SWAN GIS plugin is designed to work with all [https://gdal.org/drivers/raster/index.html GDAL compatible raster formats] as well as [https://ugrid-conventions.github.io/ugrid-conventions/ UGRID] and [https://www.xmswiki.com/wiki/TIN_Files Aquaveo SMS TIN] mesh formats.

Coarse bathymetry can be sourced from the global [https://www.gebco.net/data_and_products/gridded_bathymetry_data/ GEBCO] dataset. Go to https://download.gebco.net/ and follow these steps:

<ol>
    <li>Enter the subset extents: longitude (149.27, 162.53), latitude (-31.00, -22.43)</li>
    <li>Tick the GeoTIFF Grid format option
    <li>Click the 'Add to basket' button
    <li>Click the 'View basket' button
    <li>Click the 'Download your data' button
    <li>Save the data to your '''\Moreton_Bay_Waves\DATA\BATHY folder'''
</ol>

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[[File: SWAN_GETTING_INPUT_DATA_001.PNG | 800px]]
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For near-shore wave modelling, the GEBCO data set is typically too coarse, therefore it is best to have a higher resolution data set for the area of interest. For our near-shore areas, we will overwrite the GEBCO data set with more accurate data from an Australian Digital Terrain Model (DTM) database accessed via https://elevation.fsdf.org.au/. Go to the webpage and follow these steps:

<ol>
    <li>Enter the subset extents: longitude (152.79, 153.99), latitude (-28.16, -26.56)</li>
    <li>Tick the 'High-resolution depth model for the Great Barrier Reef' option
    <li>Click the 'Download selected datasets' button
    <li>Set the output coordinate system to WGS84
    <li>Set the output format to GeoTIFF
    <li>Enter user credentials
    <li>Click 'Start extract of datasets' button
    <li>Save the data to your '''\Moreton_Bay_Waves\DATA\BATHY folder'''
</ol>

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=Wind Data=
The SWAN GIS plugin is designed to utilise gridded wind data from the [https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5 European Centre for Medium Range Weather Forecasting (ECMWF) Reanalysis 5 (ERA5) dataset] in netCDF4 format or alternatively a spatially constant time series in CSV format. This section shows how to download ERA5 wind data from the Copernicus Climate Data Store (CDS). Before the application can be accessed you will need to create a Climate Data Store account [https://cds.climate.copernicus.eu/user/login here].

Login to your CDS account and navigate to this [https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form webpage]. To request the data follow these steps:
<ol>
    <li>Tick 'Reanalysis' product type</li>
    <li>Select variables 10m u-component of wind and 10m v-component of wind</li>
    <li>Select the year 2018 </li>
    <li>Select months September and August </li>
    <li>Select all days</li>
    <li>Select all times</li>
    <li>Enter the subset extents: longitude (149, 162), latitude (-31, -22)</li>
    <li>Tick NetCDF4 format</li>
    <li>Click 'Submit Form' button</li>
</ol>

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[[File: SWAN_GETTING_INPUT_DATA_005.PNG | 800px]]
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[[File: SWAN_GETTING_INPUT_DATA_006.PNG | 800px]]

The CDS server will now process the request. The status of the request should be monitored [https://cds.climate.copernicus.eu/cdsapp#!/yourrequests?tab=form here]. When the request has been processed, click the download button for the request as shown below: 

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Save the wind data to your '''Moreton_Bay_Waves\DATA\WIND''' folder. <br><br>

=Wave Data=
The SWAN GIS plugin is designed to work with gridded spectral wave parameter data from the ERA5 dataset in netCDF4 format. To download the wave data, follow the procedure outlined in the [[SWAN_GIS_Getting_Input_Data#Wind_Data | Wind Data]] section, however alter the selected variables to:

* Peak wave period
* Significant height of combined wind waves and swell
* Mean wave direction
* Mean wave period
* Wave spectral directional width

[[File: SWAN_GETTING_INPUT_DATA_008.PNG]]<br><br>

Save the wind data to your '''Moreton_Bay_Waves\DATA\WIND''' folder. <br><br>
=Conclusion=
You have now obtained your input bathymetry, wind and wave data. We can move to Step 3 of our SWAN GIS Tools step by step guide: [[SWAN_GIS_Tools#SWAN_GIS_Tutorial | Building the Model in QGIS]].