resdlem 0.0.3
A package to calulate equilibrium function for dlem
Requires Python: >=3.8

# resdlem

## Description
The resdlem python package provides a simple means of incorporating the
Daily Lake Evaporation Model (DLEM) equilibrium function into python code.

It simply performs the calculation given the inputs. There is no unit 
support or other fluf. See below for inputs of the function and the units.

## Code Example

```
from resdlem import equilibrium

devap = equilibrium.dlemEvap(
    lat=40,
    depth=20,
    elev=1000,
    solrad=270,
    ta=10,
    vpd=1,
    pres=89651.51985730644,
    ut=5,
    tw0=10,
    fch=1000,
    mth=5,
    tds=15_000)

evap_hs = devap.evap_hs
tw = devap.tw

```

### Function inputs
| variable             | Description                                | Units         |
|----------------------|--------------------------------------------|---------------|
| lat                  | Latitude                                   | degrees       |  
| depth                | Average depth of reservoir (capacity/area) | meter         |
| elev                 | Elevation of water surface                 | meter         |         
| solrad               | Incoming surface shortwave solar radiation | W m-2 per day |         
| ta                   | Daily average temperature                  | Celcius       |         
| vpd                  | Vapor pressure deficit                     | kPa           |         
| pres                 | Atmospheric Pressure                       | Pa            |         
| ut                   | Wind speed at 2m                           | m s-1         |         
| tw0                  | Water temp from previous timestep (tw)     | Celcius       |         
| fch                  | Fetch length                               | m             |         
| mth                  | Month of interest                          | NA            |         
| tds                  | Total dissolved solids                     | ppm           |         

### Function outputs
| variable    | Description                                                       | Units        |
|-------------|-------------------------------------------------------------------|--------------|
| evap_hs     | Evaporation with Heat Storage                                     | mm/day       |
| evap_hs_adj | Evaporation with Heat Storage adjusted for total dissolved solids | mm/day       |
| evap_nhs    | Evaporation no Heat Storage (Penman Evaporation)                  | mm/day       |
| te          | Equilibrium Temperature                                           | Celcius      |
| tw          | Water column temperature at end of timestep                       | Celcius      |
| rn          | Net solar radiation                                               | W m-2 per day |
| ierr        | Calculation code error (See Error Table)                          |              |

## Error Table (ierr)
| value | Description                                                     |
|-------|-----------------------------------------------------------------|
| 0     | Timestep is good                                                |
| 2     | Depth is less than or equal to 0                                |
| 3     | Air temperature is less than wet bulb temperature               |
| 4     | Downloading solar radiation is less than 0                     |
| 5     | Wind speed is less than 0.01m/s                                 |
| 6     | Vapor Pressure Deficit is less than or euqal to 0               |
| 7     | Vapor pressure deficit is greater than saturated vapor pressure |


Citation

Zhao, B., Huntington, J., Pearson, C., Zhao, G., Ott, T., Zhu, J.,
Weinberg, A., Holman, K. D., Zhang, S.,Anderson,
R., Strickler, M., Cotter, J., Fernando, N., Nowak, K.,
& Gao, H. (2024).Developing a general Daily Lake Evaporation
Model and demonstrating its application inthe state of Texas.
Water Resources Research, 60(3), e2023WR036181.
Available at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023WR036181