R02B06 ICON External Parameter Request An In-Depth Discussion

by StackCamp Team 62 views

Hey guys! Let's dive into the specifics of this ICON external parameter request. This discussion revolves around a request for setting up external parameters for the ICON model, focusing on a specific grid configuration and domain setup. We'll break down the details, making sure everything is crystal clear.

Understanding the Request

The core of this request is a JSON configuration detailing the setup needed for the ICON model. JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate. This particular JSON includes specifications for Zonda, basegrid, and multiple domains. Let's walk through each section to understand its purpose and implications.

Zonda Configuration

First up, the "zonda" section specifies the tags for icontools and extpar. This part is crucial for ensuring the correct versions of the software components are used.

 "zonda": {
 "icontools_tag": "master",
 "extpar_tag": "v5.18.1"
 }

The icontools_tag set to "master" indicates that we're using the latest version of the ICON tools. The extpar_tag set to "v5.18.1" specifies a particular version of the external parameter library. Using specific tags helps maintain consistency and reproducibility in our simulations. These tags are essentially pointers to specific versions of the codebase, ensuring that everyone is working with the same software environment. It’s like specifying the exact ingredients and recipe version for a cake – you want to make sure you get the same delicious result every time!

Basegrid Configuration

The "basegrid" section defines the fundamental grid structure for the model. This is where we set the stage for the simulation's spatial resolution and orientation. Key parameters here include grid_root, grid_level, outfile, icorotation, icopole_lat, icopole_lon, centre, and subcentre.

 "basegrid": {
 "keep_basegrid_files": false,
 "grid_root": 2,
 "grid_level": 5,
 "outfile": "R02B06",
 "icorotation": 0,
 "icopole_lat": 90,
 "icopole_lon": 0,
 "centre": 78,
 "subcentre": 255
 }
  • keep_basegrid_files: Set to false, this indicates that the basegrid files don't need to be preserved after processing, saving storage space.
  • grid_root and grid_level: These parameters define the resolution of the grid. A higher grid_level means a finer resolution, allowing for more detailed simulations. For instance, grid_level 5 creates a relatively high-resolution grid, capturing finer details in the simulation.
  • outfile: This specifies the name of the output file, which in this case is "R02B06". This naming convention helps in organizing and identifying different simulation setups.
  • icorotation: Set to 0, indicating no rotation of the grid.
  • icopole_lat and icopole_lon: These define the latitude and longitude of the pole for the grid's coordinate system. Here, the pole is set at 90° latitude and 0° longitude, which is the North Pole in a standard geographical coordinate system.
  • centre and subcentre: These parameters are related to the GRIB (GRIdded Binary) encoding used in weather and climate models. They help in defining the data's origin and structure within the GRIB format.

Domain Configurations

The "domains" section is where the request gets really interesting. It specifies the setup for multiple nested domains, each with its own set of icontools and extpar configurations. Nested domains allow us to focus computational resources on areas of interest, providing higher resolution where it matters most.

Each domain configuration includes:

  • domain_id: A unique identifier for the domain.
  • icontools: Settings related to the ICON tools, such as the parent domain, center coordinates, and domain size.
  • extpar: External parameter settings, including types of data to use and various flags.

Let’s look at the first domain configuration as an example:

 {
 "domain_id": 1,
 "icontools": {
 "parent_id": 0,
 "center_lat": -2.15,
 "center_lon": -59.55,
 "hwidth_lat": 17.5,
 "hwidth_lon": 25.5,
 "lrotate": false,
 "pole_lat": 90,
 "pole_lon": -180,
 "region_type": 3
 },
 "extpar": {
 "use_array_cache": false,
 "iaot_type": 1,
 "ilu_type": 1,
 "ialb_type": 1,
 "isoil_type": 1,
 "itopo_type": 1,
 "it_cl_type": 1,
 "iera_type": 1,
 "iemiss_type": 1,
 "lradtopo": false,
 "enable_cdnc": false,
 "enable_edgar": false,
 "radtopo_radius": 40000,
 "nhori": 24,
 "enable_art": false,
 "l_use_corine": false,
 "ilookup_table_lu": 1,
 "tcorr_lapse_rate": 0.0065,
 "tcorr_offset": 0
 }
 }

IContools Configuration

The icontools section for each domain defines the geographical extent and positioning. Key parameters include parent_id, center_lat, center_lon, hwidth_lat, hwidth_lon, lrotate, pole_lat, pole_lon, and region_type.

  • parent_id: This indicates the parent domain. A parent_id of 0 means this is the outermost domain. Subsequent domains have a parent_id corresponding to the domain_id of their parent, creating a nested structure.
  • center_lat and center_lon: These define the latitude and longitude of the domain's center. For example, the first domain is centered at -2.15° latitude and -59.55° longitude, which is a location in South America.
  • hwidth_lat and hwidth_lon: These parameters specify the half-width of the domain in latitude and longitude degrees, determining the domain's size. The first domain has a half-width of 17.5° in latitude and 25.5° in longitude, defining a rectangular area around the center point.
  • lrotate: Set to false, indicating that the domain is not rotated.
  • pole_lat and pole_lon: Similar to the basegrid, these define the pole for the domain's coordinate system. Here, the pole is set at 90° latitude and -180° longitude.
  • region_type: This specifies the type of region. A region_type of 3 often indicates a rectangular domain.

Extpar Configuration

The extpar section is where we configure the external parameters for the model. These parameters include settings for land surface data, orography, and other environmental factors. Let's break down the key settings:

  • use_array_cache: Set to false, meaning the array cache is not used.
  • iaot_type, ilu_type, ialb_type, isoil_type, itopo_type, it_cl_type, iera_type, iemiss_type: These parameters specify the types of data used for various land surface properties such as aerosol optical thickness, land use, albedo, soil type, topography, cloud type, vegetation, and emissivity. A value of 1 typically indicates the use of default datasets.
  • lradtopo: This flag controls whether or not to use radiation-aware topography. For the first three domains, it's set to false, but for the fourth domain, it's set to true. This means that the fourth domain will incorporate detailed topographic information in radiation calculations, which can be crucial for simulating local climate effects.
  • enable_cdnc and enable_edgar: Both set to false, disabling the use of cloud droplet number concentration (CDNC) and emissions data from the EDGAR (Emission Database for Global Atmospheric Research) inventory.
  • radtopo_radius: This parameter defines the radius around a grid point within which topographic effects are considered for radiation calculations. It's set to 40,000 meters (40 km) in this configuration.
  • nhori: Set to 24, this parameter likely relates to the number of points used in a horizontal interpolation or smoothing process.
  • enable_art: This flag controls the activation of aerosol radiative effects. It's set to false for the first three domains but true for the fourth domain, indicating that the fourth domain will include the radiative effects of aerosols in the simulation.
  • l_use_corine: Set to false, disabling the use of CORINE (Coordination of Information on the Environment) land cover data.
  • ilookup_table_lu: Set to 1, specifying the type of lookup table used for land use data.
  • tcorr_lapse_rate and tcorr_offset: These parameters are related to temperature correction based on altitude, with a lapse rate of 0.0065 °C/meter and an offset of 0.

Nested Domains

The configuration includes four nested domains. Each subsequent domain has a smaller hwidth_lat and hwidth_lon, effectively zooming in on the area of interest. This is a common technique in numerical weather prediction and climate modeling to increase resolution in specific regions.

  • Domain 1: The largest domain, providing a broad overview.
  • Domain 2: A smaller domain nested within Domain 1, providing higher resolution.
  • Domain 3: Even smaller, nested within Domain 2, for further refinement.
  • Domain 4: The smallest and highest resolution domain, nested within Domain 3. This domain also has lradtopo and enable_art set to true, indicating a focus on detailed radiation and aerosol effects.

Key Configurations and Their Importance

High-Resolution Nesting

The use of nested domains is a standout feature of this request. By setting up multiple domains, each smaller than the last, we can achieve high resolution in the area of interest while maintaining computational efficiency. This is crucial for accurately simulating local weather phenomena and climate patterns.

Domain-Specific Parameter Settings

Notice that Domain 4 has lradtopo and enable_art set to true. This highlights the flexibility of the configuration, allowing for domain-specific settings. In this case, the innermost domain is configured to consider detailed topographic and aerosol radiative effects, which might be essential for capturing local climate dynamics.

External Parameter Choices

The extpar settings, such as the choice of data types for land surface properties (iaot_type, ilu_type, etc.), are vital for the accuracy of the simulation. These choices determine the datasets used to represent various environmental factors, influencing the model's behavior and outputs.

Steps to Process the Request

The instructions provided outline the steps to submit and manage the request:

  1. Meaningful Title: Start by giving the issue a descriptive title, including domain name, grid specifications, and project details.
  2. Paste JSON Request: Replace PASTE_YOUR_REQUEST_HERE with the JSON configuration.
  3. Preview JSON: Verify the JSON format using the “Preview” tab to ensure it’s correctly formatted.
  4. Submit Request: Click “Create” to submit the data request.

Managing the Request

Once submitted, Zonda will process the data. The instructions also provide guidance on how to manage the request:

  • Resubmission: Use the comment “rerun request” to resubmit the data request.
  • Pinging Maintainers: If issues arise, ping a maintainer (e.g., @stelliom or @mjaehn) and provide relevant logfile information.

Understanding Status Labels

The status labels give a quick overview of the request's progress:

  • Static Badge – Request is under processing.
  • Static Badge – Request processed successfully, and data is available via a provided link.
  • Static Badge – Request could not be processed; check log files for details.
  • Static Badge – Request was aborted, possibly due to a timeout. Try again or contact support.

Conclusion

This ICON external parameter request is a well-structured configuration for setting up a high-resolution simulation with nested domains. Understanding the specifics of the JSON configuration, including the Zonda settings, basegrid parameters, and domain configurations, is essential for ensuring the simulation runs as expected. By following the outlined steps and keeping an eye on the status labels, we can effectively manage this request and obtain the necessary data for our modeling needs. Let’s make sure we keep the communication lines open and address any issues promptly to keep things running smoothly, guys! Remember, clear communication and thorough understanding are key to successful simulations.