# ET.BlaneyCriddle

##### Blaney-Criddle Formulation

Implementing the Blaney-Criddle formulation for estimating reference crop evapotranspiration.

##### Usage

```
# S3 method for BlaneyCriddle
ET(data, constants, ts="daily", solar="sunshine hours", height = F , …)
```

##### Arguments

- data
A list of data which contains the following items (climate variables) required by Blaney-Criddle formulation:

*Tmax*,*Tmin*,*RHmin*,*n*or*Cd*,*u2*or*uz*- constants
A list named

`constants`

consists of constants required for the calculation of PenPan formulation which must contain the following items:*Elev*- ground elevation above mean sea level in m,*lambda*- latent heat of vaporisation = 2.45 MJ.kg^-1,*lat_rad*- latitude in radians,*z*- height of wind instrument in m,*e0*,*e1*,*e2*,*e3*,*e4*- recommended values of 0.81917, -0.0040922, 1.0705, 0.065649, -0.0059684, -0.0005967 respectively (Table 1 in Frevert et al., 1983).- ts
Must be either

`daily`

,`monthly`

or`annual`

, which indicates the disired time step that the output ET estimates should be on. Default is`daily`

.- solar
Must be either \codesunshine hours or

`cloud`

:`sunshine hours`

indicates that solar radiation is to be calculated using the real data of sunshine hours;`cloud`

sunshine hours is to be estimated from cloud data. Default is`sunshine hours`

.- height
Must be

`T`

or`F`

, indicating if adjustment for site elevation for arid and semi-arid regions is applied in Blaney-Criddle formulation (Allen and Brockway, 1983). Default is`F`

for no adjustment.- …
Dummy for generic function, no need to define.

##### Details

The alternative calculation options can be selected through argument `solar`

, please see `Arguments`

for details.
Height adjustment for the estimations is available through argument `height`

, please see `Arguments`

for details.

##### Value

The function prints a calculation summary to the screen containing the following elements:
- ET model name and ET quantity estimated
- Evaporative surface
- Option for calculating solar radiation (i.e. the value of argument `solar`

)
- If height adjustment has been applied on results (i.e. the value of argument `height`

)
- Time step of the output ET estimates (i.e. the value of argument `ts`

)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including *mean*, *max* and *min* values.

The function also generates a list containing the following components, which is saved into a `csv`

file named as *ET_BlaneyCriddle.csv* in the working directory:

Daily aggregated estimations of Blaney-Criddle reference crop evapotranspiration.

Monthly aggregated estimations of Blaney-Criddle reference crop evapotranspiration.

Annually ggregated estimations of Blaney-Criddle reference crop evapotranspiration.

Monthly averaged estimations of daily Blaney-Criddle reference crop evapotranspiration.

Annually averaged estimations of daily Blaney-Criddle reference crop evapotranspiration.

Name of the formulation used which equals to `Blaney-Criddle`

.

Type of the estimation obtained which is `Reference Crop Evapotranspiration`

.

A message to inform the users about how solar radiation has been calculated by using which data.

A message to inform the users about if height adjustment has been applied to calculated Blaney-Criddle reference crop evapotranspiration.

##### References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. *Estimating actual, potential, reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis*. Hydrology and Earth System Sciences Discussions, 9, 11829-11910.

Allen, R.G.Brockway, C.E. 1983, *Estimating consumptive use on a statewide basis*. Advances in Irrigation and Drainage@ sSurviving External Pressures, ASCE, pp. 79-89.

Allen, R. & Pruitt, W. 1986. *Rational Use of The FAO Blaney-Criddle Formula*. Journal of Irrigation and Drainage Engineering, 112, 139-155.

Frevert, D.K., Hill, R.W.Braaten, B.C. 1983, *Estimation of FAO evapotranspiration coefficients*, Journal of Irrigation and Drainage Engineering, vol. 109, no. 2, pp. 265-270.

##### See Also

##### Examples

```
# NOT RUN {
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")
# Call ET.BlaneyCriddle under the generic function ET
results <- ET.BlaneyCriddle(data, constants, ts="daily", solar="sunshine hours", height= FALSE)
# }
```

*Documentation reproduced from package Evapotranspiration, version 1.10, License: GPL (>= 2)*