NAME
i.evapo.senay - Actual evapotranspiration, method after Senay (2007)
KEYWORDS
Actual ET,
evapotranspiration,
Senay
SYNOPSIS
i.evapo.senay
i.evapo.senay --help
i.evapo.senay [-edb] temperature=name albedo=name elevation=name [latitude=name] [dayofyear=name] [transmissivitysingleway=name] [waterdensity=float] [slope=name] [aspect=name] [atmosphericemissivity=float] [airtemperature=name] [surfaceemissivity=name] ndvi=name [diurnaletpotential=name] output=name [evapfr=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -e
- ET Potential Map as input (By-Pass creation of one)
- -d
- Slope/Aspect correction
- -b
- Net Radiation Bandara (1998), generic Longwave calculation, need apparent atmospheric emissivity, Air temperature and surface emissivity inputs
- --overwrite
- Allow output files to overwrite existing files
- --help
- Print usage summary
- --verbose
- Verbose module output
- --quiet
- Quiet module output
- --ui
- Force launching GUI dialog
Parameters:
- temperature=name [required]
- Name of the temperature layer [Degree Kelvin]
- albedo=name [required]
- Name of the Albedo layer [0.0-1.0]
- elevation=name [required]
- Name of the elevation layer [m]
- latitude=name
- Name of the degree latitude layer [dd.ddd]
- dayofyear=name
- Name of the Day of Year layer [0.0-366.0]
- transmissivitysingleway=name
- Name of the single-way transmissivity layer [0.0-1.0]
- waterdensity=float
- Value of the density of fresh water ~[1000-1020]
- Default: 1005.0
- slope=name
- Name of the Slope layer ~[0-90]
- aspect=name
- Name of the Aspect layer ~[0-360]
- atmosphericemissivity=float
- Value of the apparent atmospheric emissivity (Bandara, 1998 used 0.845 for Sri Lanka)
- airtemperature=name
- Name of the Air Temperature layer [Kelvin], use with -b
- surfaceemissivity=name
- Name of the Surface Emissivity layer [-], use with -b
- ndvi=name [required]
- Name of the NDVI layer [-]
- diurnaletpotential=name
- Name of the ET Potential layer [mm/day]
- output=name [required]
- Name of the output Actual ET layer
- evapfr=name
- Name of the output evaporative fraction layer
i.evapo.senay Calculates the diurnal actual
evapotranspiration after Senay (2007). This is converting all Net
radiation from the diurnal period into ET, then uses Senay equation
for evaporative fraction.
It takes input maps of Albedo, surface skin temperature, latitude,
day of year, single-way transmissivity and takes input value of the
density of fresh water.
DEM is used for calculating min and max temperature for Senay equation.
The "-s" flag permits output map of evaporative fraction from Senay.
If you are trying to map irrigated crops, and you know there is at least
one crop pixel that is evapotranspiring at maximum (ETa=ETpot), then read this.
i.evapo.senay is highly dependent on the wet pixel being
the lowest temperature in the crop pixels to work for non water
stressed crops, force it that way, even if it breaks non crop areas.
I suggest you reduce your region to the irrigation system
boundaries, checking that it includes a bit of dry area for the
hot/dry pixel.
Since it is a direct relationship to LST, evaporative fraction can
be very sensitive to the kind of pixel sample you feed it with.
r.sun,
i.albedo,
i.eb.eta,
i.eb.evapfr,
i.evapo.potrad
Chemin, Y., 2012.
A Distributed Benchmarking Framework for Actual ET Models,
in: Irmak, A. (Ed.), Evapotranspiration - Remote Sensing and Modeling. InTech.
(PDF)
Yann Chemin, International Rice Research Institute, The Philippines.
SOURCE CODE
Available at:
i.evapo.senay source code
(history)
Latest change: Monday Jan 30 19:52:26 2023 in commit: cac8d9d848299297977d1315b7e90cc3f7698730
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