Grow Degree Calculator

Grow Degree Calculator application.

The Grow Degree Calculator (GDC) project is based on the WRF Hindcast project and calculates the Grow Degree values for either crops or insects. Users can enter the temperature parameters, location, and start and end dates for the organism of interest. Output includes an image of the total accumulated values over the target sector, a plot of accumulated values over time, and a text report.

Accumulated grow degree values are important for agriculture because it can accurately predict organism behavior. For example, knowing the accumulated grow degree values throughout a season, farmers can say when orchard trees will blossom, or when insects will hatch, and more. Click here to use the GDC application.

Procedure

The GDC application calculates a location's accumulated grow degree value from historical WRF Hindcast data stored on our server. The user customizes the calculation request by entering temperature parameters, location, and run dates. The application determines which sector and data pixel to use, gets historical daily minimum and maximum temperatures, calculates and accumulates the grow degree units over the run dates given for the pixel location.

GDC application with numbered sections

Input section

Temps (celsius)

Organisms (plants and insects) have a range of temperatures in which they can grow. Example: 5, 30

    base  5
      The base input value (celsius) is the lowest temperature at which the organism can grow.
    upper  30
      The upper input value (celsius) is the highest temp at which the organism can grow.

Location (decimal degrees)

Note: currently about 1/3 of the geographical area of the contiguous 48 states is available for processing. See WRF Hindcast for current operational sectors. If the values are not within the active sectors, error messages will appear in the text report panel of the application.

The latitude and longitude values of the area of interest, in decimal form. Example: 32.25049, -106.74516

    latitude  32.25049

    longitude  -106.74516

Rundates (yyyymmdd)

The start and end date specify when to accumulate the grow degree values. Dates are given in the YYYYMMDD format, eg. March 5, 2017 would be 20170305. Example: January 1, 2017; April 6, 2017

    start  20170101

    end  20170406

Apply

Run the application with the provided values of Temps, Location, and Rundates

Output section

Three images: 3.3km, 10km, 30km

Based on the latitude and longitude values provided by the user, clicking on a tab will display the processed accumulated Grow Degree image of the area of interest. All 3 images are 171 x 171 pixels in size but the resolution of each pixel varies in each of the 3.

    3.3km  each pixel in this image represents an area approximately 3.3 km by 3.3 km.

    10km   each pixel in this image represents an area approximately 10 km by 10 km.

    30km   each pixel in this image represents an area approximately 30 km by 30 km.

Clicking on the '+' in the image will 'zoom-in' the image.

Clicking on the '-' in the image will 'zoom-out' the image.

Clicking on the 'house' in the image will restore the image to its initial display size and position.

Clicking and holding down the left button on the mouse enables moving the image.

In the 3.3km image you should see a small blinking black square in the image. Your latitude and longitude of interest will be inside this square. Use the '+' sign or the wheel on your mouse to zoom in. Move the mouse around inside the square until the latitude and longitude values shown in #6 approximate the values you entered in #2 for latitude and longitude. It is very unlikely they will match exactly.

If you don't see the small blinking black square it's because the underlying or surrounding area is also black or blackish. In this case move the mouse around in the image and look at the latitude and longitude values displayed in #6 until you have homed in on the desired area, then zoom in, etc.

Latitude, Longitude, GDC value

Each pixel of the displayed image (171 x 171 pixels = 29,241 total pixels) has values representing the pixel's latitude, longitude, and the calculated Grow Degrees. Move your mouse over the image and watch #6 to see the results.

Text report

Text description of the GDC run and its results.