5. Create Crop2ML ModelUnit

Remind that a Crop2ML ModelUnit is composed of its specification (meta-information) represented in a xml file to which is associated an algorithm representing the relationship between the inputs and the outputs of the model.

5.1. How

To create a Crop2ML ModelUnit in CropMStudio:

  1. On the home interface click on Model Creation

  2. Select Model Unit

  3. Then fill the different tables with the information related to the ModelUnit.

  • General information (name, id, version, …)

  • Declaration of inputs and outputs (click on Add to create a new row for a new input or output)

  • Select initialisation if needed

  • A Parametersets section will appear if the ModelUnit contains parameters. In this case: + Create a Parameterset by filling its name and description + A table of the ModelUnit parameters will be opened. Then, set the parameters for unit tests. + Other Parameterset can be created.

  • Finally, Testsets section appears. + Create a Testset by clicking on Create in Testset Line and by filling its name and description. Associate a Parameterset by selecting its name. + Create one or several tests in this Testset. To create a Test, select Create in Test line. Then, a table of the ModelUnit inputs and outputs will be opened. Then, set the inputs and the expected values of the outputs for unit tests. + Several Testset can be created.

5.2. Exercise:

Consider that you would like to create two simple ModelUnits in the Energy Balance package : Net Radiation and Net radiation in equivalent evaporation. Then in the next lines, the meta-information is provided with model equations in order to create two Crop2ML ModelUnits.

Net radiation

  • Model equations in CyML

1cdef float Nsr, clearSkySolarRadiation, averageT, surfaceEmissivity, cloudCoverFactor, Nolr
2Nsr = (1.0 - albedoCoefficient) * solarRadiation
3clearSkySolarRadiation = (0.75 + 2 * pow(10.0, -5) * elevation) * extraSolarRadiation
4averageT = (pow(maxTair + 273.16, 4) + pow(minTair + 273.16, 4)) / 2.0
5surfaceEmissivity = (0.34 - 0.14 * sqrt(vaporPressure / 10.0))
6cloudCoverFactor = (1.35 * (solarRadiation / clearSkySolarRadiation) - 0.35)
7Nolr = stefanBoltzman * averageT * surfaceEmissivity * cloudCoverFactor
8netRadiation= Nsr - Nolr

  • Model meta-information

Parameters meta-information

name

description

default

min

max

unit

albedoCoefficient

albedo Coefficient

0.23

0.0

1.0

unitless

stefanBoltzman

stefan Boltzman constant

4.903E-09

0.0

1.0

unitless

elevation

elevation

0

-5000

10000

m
Variables meta-information

name

description

default

min

max

unit

minTair

minimum air temperature

0.7

-30

45.0

degC

maxTair

maximum air Temperature

7.2

-30.0

45.0

degC

solarRadiation

solar radiation

3

0.0

10000.0

MJ/(m**2*d)

vaporPressure

vapor Pressure

6.1

0.0

10000.0

hPa

extraSolarRadiation

extra Solar Radiation

11.7

0.0

1000.0

m

netRadiation

net Radiation

0.0

5000.0

MJ/(m**2*d)

Net radiation in equivalent evaporation

  • Model equations in CyML

netRadiationEquivalentEvaporation = netRadiation / lambdaV * 1000.0

  • Model meta-information

Parameters meta-information

name

description

default

min

max

unit

lambdaV

latent heat of vaporization of water

2.454

0.0

10.0

MJ/kg
Variables meta-information

name

description

default

min

max

unit

netRadiation

net Radiation

1.566

0.0

5000.0

MJ*m-2*d-1

netRadiationEquivalentEvaporation

net Radiation in Equivalent Evaporation

0.0

5000.0

g/(m**2*d)

Look at the process of Crop2ML ModelUnit Creation through the video