Converting CORDEX NetCDF Data for Import into DHI Mike: A Step-by-Step Guide

Climate data are an essential component of Earth science research. The Coordinated Regional Climate Downscaling Experiment (CORDEX) is a global initiative to produce high-resolution regional climate change projections. CORDEX data are stored in the NetCDF format, which is widely used in Earth science research. DHI Mike is a powerful modeling software for water resources management that supports the import of NetCDF data. This article provides a step-by-step guide on how to convert CORDEX NetCDF data so that it can be used to import data into DHI Mike.

Step 1: Install the required software

The first step is to install the necessary software. You will need to install the NetCDF Operators (NCO) and the Climate Data Operators (CDO) on your system. NCO is a command line tool that allows you to manipulate NetCDF files, while CDO is a set of command line tools that allow you to process and analyze climate data.

You can install NCO and CDO on Ubuntu or Debian based systems with the following command

sudo apt-get install nco cdo

Alternatively, you can download and install the software from the official websites. NCO can be downloaded from https://github.com/nco/nco and CDO can be downloaded from https://code.mpimet.mpg.de/projects/cdo/.

Step 2: Subset the CORDEX data

The next step is to subset the CORDEX data to extract the desired variables and spatial and temporal extent. The NCO tool can be used to subset the data. The following command will extract the temperature variable for the North American region from the CORDEX NetCDF file:

ncks -v tas -d lon,-140.0,-50.0 -d lat,20.0,70.0 -d time,2006-01-01,2006-12-31 input_file.nc output_file.nc

The above command extracts the temperature variable (-v tas) for the longitude range from -140.0 to -50.0 degrees and the latitude range from 20.0 to 70.0 degrees (-d lon,-140.0,-50.0 -d lat,20.0,70.0) for the time period from 2006-01-01 to 2006-12-31 (-d time,2006-01-01,2006-12-31). The extracted data is saved in the output_file.nc file.

Step 3: Convert the NetCDF file to ASCII format

DHI Mike requires that the data be in ASCII format for import. You can use the CDO tool to convert the NetCDF file to ASCII format. The following command converts the NetCDF file to ASCII format:

cdo -f ascii -outputtab,date,time,lon,lat,tas output_file.nc > output_file.txt

The above command converts the output_file.nc file to ASCII format (-f ascii) and outputs the data in tab-separated format with the date, time, longitude, latitude, and temperature variables (-outputtab,date,time,lon,lat,tas). The converted data is saved in the output_file.txt file.

Step 4: Import Data into DHI Mike

The final step is to import the data into DHI Mike. Open DHI Mike and choose File > Import > ASCII File. Select the output_file.txt file and click Open. The imported data will appear in the DHI Mike Data Editor. You are now ready to use the data for modeling and analysis in DHI Mike.

Conclusion

Converting CORDEX NetCDF data for import into DHI Mike requires only a few simple steps. By following the steps above, you can extract the required variables and spatial and temporal extents from the CORDEX data, convert the NetCDF file to ASCII format, and import the data into DHI Mike. This will allow you to use the powerful modeling capabilities of DHI Mike for water resources management with high resolution climate data.

FAQs

What is CORDEX data?

CORDEX data is high-resolution regional climate change projections produced by the Coordinated Regional Climate Downscaling Experiment (CORDEX). It is stored in NetCDF format and is widely used in Earth science research.

What is DHI Mike?

DHI Mike is a powerful modeling software used for water resource management. It supports importing NetCDF data, making it a valuable tool for analyzing climate data.

What software do I need to install to convert CORDEX NetCDF data for importing into DHI Mike?

You will need to install the NetCDF operators (NCO) and the Climate Data Operators (CDO) on your system. NCO is a command-line tool that allows you to manipulate NetCDF files, while CDO is a set of command-line tools that allows you to process and analyze climate data.

How do I subset the CORDEX data?

You can use the NCO tool to subset the CORDEX data. The command for extracting the required variables and spatial and temporal extents may vary depending on your requirements, but the general format is as follows: ncks -v variable -d lon,lon_min,lon_max -d lat,lat_min,lat_max -d time,start_date,end_date input_file.nc output_file.nc

How do I convert the NetCDF file to ASCII format?

You can use the CDO tool to convert the NetCDF file to ASCII format. The command for converting the NetCDF file to ASCII format is as follows: cdo -f ascii -outputtab,date,time,lon,lat,variable input_file.nc > output_file.txt

How do I import the data into DHI Mike?

To import the data into DHI Mike, open DHI Mike and select File > Import > ASCII file. Select the output_file.txt file and click on Open. The imported data will be displayed in the DHI Mike data editor.

What are the benefits of converting CORDEX NetCDF data for importing into DHI Mike?

Converting CORDEX NetCDF data for importing into DHI Mike allows you to use the powerful modeling capabilities of DHI Mike with high-resolution climate data. This is particularly useful for water resource management, as it enables you to make more accurate predictions and better manage water resources in the face of climate change.