# ET.JensenHaise

##### Jensen-Haise Formulation

Implementing the Jensen-Haise formulation for estimating potential evapotranspiration.

##### Usage

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

##### Arguments

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

*Tmax*,*Tmin*,*Rs*or*n*or*Cd*- constants
A list named

`constants`

consists of constants required for the calculation of Jensen-Haise 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,*Gsc*- solar constant = 0.0820 MJ.m^-2.min^-1.The following constants are also required when argument

`solar`

has value of`sunshine hours`

:*as*- fraction of extraterrestrial radiation reaching earth on sunless days,*bs*- difference between fracion of extraterrestrial radiation reaching full-sun days and that on sunless days.- 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

`data`

,`sunshine hours`

,`cloud`

or`monthly precipitation`

:`data`

indicates that solar radiation data is to be used directly for calculating evapotranspiration;`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;`monthly precipitation`

indicates that solar radiation is to be calculated directly from monthly precipitation. Default is`sunshine hours`

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

##### Details

This formulation provides a single calculation method with no alternatives available.

##### Value

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

)
- 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_JensenHaise.csv* in the working directory:

Daily aggregated estimations of Jensen-Haise potential evapotranspiration.

Monthly aggregated estimations of Jensen-Haise potential evapotranspiration.

Annually aggregated estimations of Jensen-Haise potential evapotranspiration.

Monthly averaged estimations of daily Jensen-Haise potential evapotranspiration.

Annually averaged estimations of daily Jensen-Haise potential evapotranspiration.

Name of the formulation used which equals to `Jensen-Haise`

.

Type of the estimation obtained which is `Potential Evapotranspiration`

.

##### References

Jensen, M.E.Haise, H.R. 1963, *Estimating evapotranspiration from solar radiation*. Proceedings of the American Society of Civil Engineers, Journal of the Irrigation and Drainage Division, vol. 89, pp. 15-41.

Prudhomme, C.Williamson, J. 2013, *Derivation of RCM-driven potential evapotranspiration for hydrological climate change impact analysis in Great Britain: a comparison of methods and associated uncertainty in future projections*. Hydrol. Earth Syst. Sci., vol. 17, no. 4, pp. 1365-1377.

Xu, C.Y.Singh, V.P. 2000, *Evaluation and generalization of radiation-based methods for calculating evaporation*., Hydrological Processes, vol. 14, no. 2, pp. 339-349.

##### See Also

##### Examples

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

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