Model Inputs¶

RefET¶

The RefET module calculates hourly or daily reference ET from meteorological data using the approach described in ASCE-NWRI (2005). If needed, the module will estimate solar radiation and dew point temperature, and gap fill meteorological data.

Meteorology Metadata¶

Meteorology Data¶

The RefET module requires hourly or daily meteorological data. If the calculated reference ET will be used in the CropET module, care should be taken to ensure this meteorological data is representative of agricultural conditions. Meteorological data can be obtained from agricultural weather networks, or adjustments reference ET can be made within the CropET module.

Timeseries Data¶

Daily Variables¶

Date [in YYYY-MM-DD format]
T_max = maximum daily air temperature
T_min = minimum daily air temperature
T_d = mean daily dew point temperature^a
e_a = actual vapor pressure^a
u_x = mean daily wind speed at known height^b
R_n = calculated net radiation at the crop surface^c
P_r = daily precipitation (optional)
Q = specific humidity (optional)
S_n = daily accumulated snow (optional)
S_d = snow depth (optional)

^a One of these is required. If both T_d and e_a are not provided, mean monthly dew point depression, K₀, must be provided.

^b Wind measurement height in meters must be provided in the ini file.

^c If R_n is not provided it will be estimated using the approach described in Thornton and Running (1998). The three Thornton and Running coefficients must be provided in the ini file.

Hourly Variables¶

Date [in YYYY-MM-DD HH:MM format]
T_mean = mean hourly air temperature
T_d = mean hourly dew point temperature^a
u_x = mean hourly wind speed at known height^b
R_n = calculated net radiation at the crop surface^c
P_r = hourly precipitation (optional)
Q = specific humidity (optional)
S_n = hourly accumulated snow (optional)
S_d = snow depth (optional)

^a One of these is required. If both T_d and e_a are not provided, mean monthly dew point depression, K₀, must be provided.

^b Wind measurement height in meters must be provided in the ini file.

^c If R_n is not provided it will be estimated using the approach described in Thornton and Running (1998). The three Thornton and Running coefficients must be provided in the ini file.

# HOW IS THE SNOW OR SNOW DEPTH USED?

File Format¶

RefET requires the timeseries weather data to be in delimited columns with header of column names. Column names and units are specified in the ini file. Files are allowed to have header rows, with the number of header rows specified in the ini file. The delimiter is also specified in the INI file.

Delimiter	Model Notation
Comma	,
Tab	/t

Format: .csv, .txt, .dat
File Name: (DESCRIBE WILDCARDS)
Structure:

Date	Tmax	Tmin	ux	Rn	Tdew
2017-10-01	9.34	3.70	3.95	120.93	3.21
2017-10-02	5.52	-2.12	7.54	59.10	-3.18
…	…	…	…	…	…

Units

Class	Variables	Units	Model Notation
Temperature	T_max, T_min, T_d	°C °F °K	c f k
Wind Speed	u_x	m s^-1 m d^-1 mi d^-1	m/s, mps m/d, m/day miles/d, miles/day, mpd
Solar Radiation	R_n	MJ m^-2 d^-1 W m^-2 d^-1 cal cm^-2 d^-1 langley	mj/m2, mj/m^2, mj/m2/d, mj/m^2/d, mj/m2/day, mj/m^2/day w/m2, w/m^2 cal/cm2’, cal/cm2, cal/cm2/d, cal/cm^2/d, cal/cm2/day, cal/cm^2/day langley
Precipitation	P_r	in d^-1 mm d^-1	in/d, in/day, inches/d, inches/day mm/d, mm/day
Humidity	Q	kg kg^-1	kg/kg
Vapor Pressure	e_a	kPa	kPa
Snow	S_n	in d^-1 mm d^-1	in/d, in/day, inches/d, inches/day mm/d, mm/day
Snow Depth	S_g	in mm	in, inches, in*100 mm

Mean Monthly Data¶

Mean monthly data are used to calculate a dew point temperature timeseries or gap fill the timeseries data if needed.

T_max = mean monthly maximum daily air temperature
T_min = mean monthly minimum daily air temperature
u_x = mean monthly wind speed at known height
K₀ = mean monthly dew point depression

File Format¶

Delimiter:

See Timeseries Data - Delimiter

Format: .csv, .txt, .dat
Structure:

Met Node ID	Met Node Name	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
BFAM	Blackfeet, MT	2.6	3.0	7.3	11.6	16.8	21.5	28.3	23.5	17.9	13.6	7.3	1.7

T:sub:`max` example shown. File structure will be the same for T_min, u_x, and K₀. Individual files are provided for each variable.

Units

See Timeseries Data - Units

Ancillary Data¶

Thornton and Running Coefficients * TR_b0 * TR_b1 * TR_b2

Thornton and Running coefficients are used to estimate solar radiation from meteorological data. These coefficients are location-specific and should be calibrated using measured solar radiation data from a representative location. The calibration approach is described in detail here

Wind Measurement Height (in meters)

CropET¶

Weather Data¶

Timeseries Data¶

The user must provide daily weather and reference ET data for each ET zone. This includes:

Date [in YYYY-MM-DD format]
T_max = maximum daily air temperature
T_min = minimum daily air temperature
T_d = mean daily dew point temperature^a
u_x = mean daily or hourly wind speed at known height^b
R_n = calculated net radiation at the crop surface^c
Q = specific humidity (optional)
S_n = daily accumulated snow (optional)
S_d = snow depth (optional)

and one of two reference ET values:

ASCEr - Daily reference ET from Penman–Monteith
ASCEg - Daily reference ET from Penman–Monteith

File Format¶

Format: .csv
Structure:

Date	TMax	TMin	Precip	Snow	SDep	EstRs	EsWind	EsTDew	ETRef [ASCEr; ASCEg]
Units	[C]	[C]	[In]	[In]	[In]	[MJ/m2]	[m/s]	[C]	[mm/day]

Location Shapefile¶

A shapefile containing the locations of each weather station is also required and is used to generate the static input files. The shapefile must contain the following attributes:

STATION_ID - Weather station ID
ETZONE_ID - Zone ID. This can include HUC8, HUC10, COUNTRYNAME, OR GRIDMET_ID
LAT - Weather station latitude
LON - Weather station longitude
[optional] ELEV [ELEV_FT; ELEV_M] - Weather station elevation in feet or meters. This field is optional and only required if running the RefET model to estimate reference ET.

File Format¶

Format: .shp
Attribute Table Structure:

STATION_ID

ZONE_ID [HUC8; HUC10; COUNTRYNAME; GRIDMET_ID]

LAT

LON

ELEV [ELEV_FT; ELEV_M]

Study Area¶

The user must provide a study area polygon shapefile with at least one feature. Each feature in the study area shapefile will become a separate ET cell/unit. Currently, only HUC8, HUC10, county, and gridmet cell shapefiles are fully supported by the prep tools.

Soils Data¶

Crop Type Data¶

Static Inputs¶

These files will be generated automatically by the CropETPrep module

CropCoefs¶

Crop coefficient curves for each crop. Generally, these values should not be modified. DESCRIBE CROP COEFFICIENTS -

CropParams¶

Crop parameters that can/should be modified during calibration.

Format: .txt
Structure:

ETCellsCrops¶

Flags controlling which crops to simulate. If using the prep workflow, the flags will initially be set based on the CDL acreage.

Format: .txt
Structure:

EToRatiosMon¶

Reference ET scale factors by month for each ET cell. This file could be used to account for a seasonal bias in the input weather data. This file is optional.

Format: .txt
Structure:

ETCellsProperties¶

Soil properties and weather station data for each ET cell. This file links the stations and the ET cells.

Format: .txt
Structure:

MeanCuttings¶

Sets the assumed number of alfalfa cuttings. This is important since the CropET module will use different crop coefficient curves for the first and last cutting.

Format: .txt
Structure: