net.simplace.sim.components.util.helper.EquationsFAO56

public class EquationsFAO56 extends Object

Helper EquationsFAO56 for computing values due to equations from (FAO 56) WIKI_START Equation numbers refers to the paper cited below. == References == - [http://www.fao.org/docrep/x0490e/x0490e00.htm (FAO 56): Allen, Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56, 1998] - (Harrison) Harrison, L.P. 1963. Fundamentals concepts and definitions relating to humidity. In A. Wexler (ed.) Humidity and moisture. Vol 3. Reinhold Publishing Company, New York. WIKI_END

Author:: Gunther Krauss

Field Summary

Fields

Modifier and Type

Field

Description

static final double

a_s_Default

default Value for Angstrom variables, regression constant

static final double

albedo

default albedo for the hypothetical grass reference crop

static final double

b_s_Default

default Value for Angstrom variables, regression slope

static final double

lambda

latent heat of vaporization [MJ kg-1]
Constructor Summary

Constructors

Constructor

Description

EquationsFAO56()
Method Summary

Modifier and Type

Method

Description

static double

ActualVapourPressureFromRelativeHumidityHourly(double e_0, double RH_hr)

Estimates hourly actual vapour pressure from hourly relative humidity Eq. (54)

static double

AdjustedKCoefficientToWindAndHumidity(double K_c, double u2, double RH_min, double h)

Adjustment of coefficient in climates where RH_min differs from 45% or where u2 is larger or smaller than 2 m/s Eq. (62) Same formula is used to adjust K_cmid [Eq. (62)], K_cend [Eq. (65)], K_cb [Eq. (70)], K_cmax [Eq. (72)], K_cbfull [Eq. (99)]

static double

AtmosphericDensity(double T_Kv, double P)

Calculates atmospheric density Eq. (3-5)

static double

AtmosphericPressure(double z)

Calculates the atmospheric Pressure P Eq. (7)

static double

ClearSkyRadiation(double R_a, double z)

Calculates the clear-sky solar radiation when values for a_s and b_s are not available Eq. (37)

static double

ClearSkyRadiationWithAngstromVariables(double R_a, double a_s, double b_s)

Calculates the clear-sky solar radiation when values for a_s and b_s are available Eq. (36)

static double

DaylightHours(double omega_s)

Dayligth hours Eq. (34)

static double

DecimalDegreesToRadians(double degree)

Convert decimal degrees to radians Eq. (22)

static double

EvaporationEquivalentToRadiation(double Radiation)

Converts radiation [energy/surface] to equivalent evaporation [depth of water] Eq. (20)

static double

EvaporationEquivalentToRadiation(double Radiation, double DailyMeanTemperature)

Converts radiation [energy/surface] to equivalent evaporation [depth of water] Correction by daily mean temperature (for 21.18°C it yields a conversion factor of 0.408) See (Harrison)

static double

ExposedAndWettedSoilFraction(double f_c, double f_w)

Exposed and wetted soil fraction Eq. (75)

static double

ExtraterrestrialRadiation(double d_r, double omega_s, double phi, double delta)

Calculates extraterrestrial radiation Eq. (21)

static double

ExtraterrestrialRadiationDiurnal(double d_r, double delta, double phi, double omega_1, double omega_2)

Diurnal extraterrestrial radiation Eq. (29(

static double

InverseRelativeDistanceEarthSun(int J)

Inverse relative distance Earth-Sun Eq. (23)

static double

KCoefficientByLAI(double K_cmin, double K_cbfull, double LAI)

Estimated basal K_cb during the mid-season when plant density is lower than full cover Eq. (97) - assumes a canopy light extiction factor of 0.7

static double

KCoefficientByLAI(double K_cmin, double K_cbfull, double LAI, double k)

Estimated basal K_cb during the mid-season when plant density is lower than full cover Eq. (97)

static double

MeanSaturatedVapourPressure(double T_max, double T_min)

Mean vapour pressure of a period Eq. (12)

static double

NetLongwaveRadiation(double R_s, double R_so, double e_a, double T_max, double T_min)

Net longwave radiation Eq. (39)

static double

NetLongwaveRadiationHourly(double R_s, double R_so, double e_a, double T)

Net longwave radiation Eq. (39) hourly

static double

NetRadiation(double R_ns, double R_nl)

Net radiation (difference between incoming shortwave and outgoing longwave radiation) Eq. (40) Remark: equation works also for hourly values.

static double

NetShortwaveRadiation(double R_s, double alpha)

Net solar or net shortwave radiation Eq. (38) Calculates the amount of solar radiation that is not reflected.

static double

NetSolarRadiation(double R_s)

Net shortvawe radiation resulting from balance of incoming and reflected solar radiation Eq. (38) Calculates the amount of solar radiation that is not reflected.

static double

p(double nominalDepletion, double ETC)

Calculates the ETC-adjusted depletion fraction/factor p.

static double

PsychrometricConstant(double P)

Calculates the psychrometric constant gamma as function of atmospheric pressure P Eq. (8) The factor is calculated from parameters for average atmospheric conditions and is rounded to 3 decimals to be consistent with the reference.

static double

ReferenceEvapotranspiration(double T, double R_n, double u_2, double e_s, double e_a, double z)

Calculates the daily crop evapotranspiration with the FAO-Penman-Montheith method Eq. (6) FAO Penman-Monteith equation determines the evapotranspiration from the hypothetical grass reference surface and provides a standard to which evapotranspiration in different periods of the year or in other regions can be compared and to which the evapotranspiration from other crops can be related.

static double

ReferenceEvapoTranspirationByExtraterrestrialRadiation(double R_a, double T_max, double T_min)

Estimates the reference evapo transpiration by extraterrestrial radiation and temperature Eq. (52)

static double

ReferenceEvapoTranspirationFromSolarRadiation(double R_s, double T_max, double T_min)

Estimates the reference evapotranspiration by solar radiation and temperature Eq. (52) & Eq. (50) with k_Rs=0.17 see: Hargreaves, Allen, 2003, History and Evaluation of Hargreaves Evapotranspiration Equation: Eq. (3)

static double

ReferenceEvapoTranspirationHourly(double R_n, double G, double T_hr, double Delta, double gamma, double e_0, double e_a, double u2)

Calculates hourly reference evapotranspiration Eq. (53)

static double

SaturationVapourPressureAtTemperature(double T)

Saturation vapour pressure at air temperature T Eq. (11)

static double

SeasonalCorrectionSolarTime(int J)

Seasonal correction for solar time Eq. (32) and (33) *

static double

SlopeOfSaturationVapPressureCurve(double T)

Calculates the slope of saturation vapour pressure curve Delta as function of temperature T Eq (13)

static double

SoilHeatFluxHourly(double t, double daylen, double R_n)

Soil heat flux for hourly periods Eq. (46)

static double

SoilHeatFluxHourlyDaylight(double R_n)

Soil heat flux for hourly periods during daylight periods Eq. (45)

static double

SoilHeatFluxHourlyNighttime(double R_n)

Soil heat flux for hourly periods during nighttime periods Eq. (46)

static double

SolarDeclination(int J)

Solar declination Eq. (24)

static double

SolarRadiation(double R_a, double n, double N, double a_s, double b_s)

Calculates Solar Radiation from sunshine hours Eq. (35)

static double

SolarRadiationFromExtraterrestrialRadiationAndTemp(double R_a, double T_max, double T_min, double k_Rs)

Estimates solar radiation by extraterrestrial radiation and temperature Eq. (50)

static double

SolarTimeAngleBeginning(double t_l, double omega)

Solar time angle at beginning of period Eq. (29)

static double

SolarTimeAngleEnd(double t_l, double omega)

Solar time angle at end of period Eq. (30)

static double

SolarTimeAngleMidpoint(double t, double L_z, double L_m, double S_c)

Solar time angel at midpoint of period Eq. (31)

static double

SunsetHourAngle(double phi, double delta)

Sunset hour angle Eq. (25)

static double

UpperLimitKCoefficient(double K_cb, double u2, double RH_min, double h)

Upper limit on the evaporation and transpiration from any cropped surface Eq. (72)

static double

VapourPressureFromDewpoint(double T_dew)

Actual vapour pressure at dewpoint Eq. (14)

static double

VapourPressureFromPsychrometricData(double T_dry, double T_wet, double a_psy, double z)

Actual vapour pressure derived from psychrometric data Eq. (15)

static double

VapourPressureFromRelHumidityMax(double RH_max, double T_min)

Actual vapour pressure from maximum relative humidity Eq. (18)

static double

VapourPressureFromRelHumidityMaxMin(double RH_max, double RH_min, double T_max, double T_min)

Actual vapour pressure from maximum and minimum relative humidity Eq. (17)

static double

VapourPressureFromRelHumidityMean(double RH_mean, double T_max, double T_min)

Actual vapour pressure from mean relative humidity Eq. (19)

static double

VegetationCoveredSoilFraction(double K_cb, double K_cmin, double K_cmax, double h)

Effective fraction of soil covered by vegetation Eq. (76)

static double

VirtualTemperature(double T_k, double e_a, double P)

Calculates virtual temperature Eq. (3-6)

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details
- a_s_Default
  
  public static final double a_s_Default
  
  default Value for Angstrom variables, regression constant
  See Also:
  
  Constant Field Values
- b_s_Default
  
  public static final double b_s_Default
  
  default Value for Angstrom variables, regression slope
  See Also:
  
  Constant Field Values
- albedo
  
  public static final double albedo
  
  default albedo for the hypothetical grass reference crop
  See Also:
  
  Constant Field Values
- lambda
  
  public static final double lambda
  
  latent heat of vaporization [MJ kg-1]
  See Also:
  
  Constant Field Values
Constructor Details
- EquationsFAO56
  
  public EquationsFAO56()
Method Details
- ReferenceEvapotranspiration
  
  public static double ReferenceEvapotranspiration(double T, double R_n, double u_2, double e_s, double e_a, double z)
  
  Calculates the daily crop evapotranspiration with the FAO-Penman-Montheith method Eq. (6) FAO Penman-Monteith equation determines the evapotranspiration from the hypothetical grass reference surface and provides a standard to which evapotranspiration in different periods of the year or in other regions can be compared and to which the evapotranspiration from other crops can be related. [FAO 56, p.65f]
  
  Parameters:
  
  T - air temperature at 2 m height [°C]
  
  R_n - net radiation at the crop surface [MJ m-2 day-1]
  
  u_2 - wind speed at 2m height [m s-1]
  
  e_s - saturation vapour pressure [kPa]
  
  e_a - actual vapour pressure [kPa]
  
  z - elevation above sea level [m]
  
  Returns:
  
  crop reference evapotranspiration ET0 [mm day-1]
- AtmosphericPressure
  
  public static double AtmosphericPressure(double z)
  
  Calculates the atmospheric Pressure P Eq. (7)
  
  Parameters:
  
  z - elevation above sea level [m]
  
  Returns:
  
  atmospheric pressure P [kPa]
- PsychrometricConstant
  
  public static double PsychrometricConstant(double P)
  
  Calculates the psychrometric constant gamma as function of atmospheric pressure P Eq. (8) The factor is calculated from parameters for average atmospheric conditions and is rounded to 3 decimals to be consistent with the reference.
  
  Parameters:
  
  P - atmospheric pressure [kPa]
  
  Returns:
  
  psychrometric constant gamma [kPa °C-1]
- SaturationVapourPressureAtTemperature
  
  public static double SaturationVapourPressureAtTemperature(double T)
  
  Saturation vapour pressure at air temperature T Eq. (11)
  
  Parameters:
  
  T - air temperature [°C]
  
  Returns:
  
  vapour pressure e_0_T [kPa]
- MeanSaturatedVapourPressure
  
  public static double MeanSaturatedVapourPressure(double T_max, double T_min)
  
  Mean vapour pressure of a period Eq. (12)
  
  Parameters:
  
  T_max - maximum air temperature during period [°C]
  
  T_min - minimum air temperature during period [°C]
  
  Returns:
  
  mean vapour pressure e_s [kPa]
- SlopeOfSaturationVapPressureCurve
  
  public static double SlopeOfSaturationVapPressureCurve(double T)
  
  Calculates the slope of saturation vapour pressure curve Delta as function of temperature T Eq (13)
  
  Parameters:
  
  T - air temperature [°C]
  
  Returns:
  
  slope of saturation vapour pressure Delta [kPa °C-1]
- VapourPressureFromDewpoint
  
  public static double VapourPressureFromDewpoint(double T_dew)
  
  Actual vapour pressure at dewpoint Eq. (14)
  
  Parameters:
  
  T_dew - dewpoint temperature [°C]
  
  Returns:
  
  actual vapour pressure e_a [kPa]
- VapourPressureFromPsychrometricData
  
  public static double VapourPressureFromPsychrometricData(double T_dry, double T_wet, double a_psy, double z)
  
  Actual vapour pressure derived from psychrometric data Eq. (15)
  
  Parameters:
  
  T_dry - dry bulb temperature [°C]
  
  T_wet - wet bulb temperature [°C]
  
  a_psy - psychrometric constant of the instrument [°C-1]
  
  z - elevation from sea level [m]
  
  Returns:
  
  actual vapour pressure e_a [kPa]
- VapourPressureFromRelHumidityMaxMin
  
  public static double VapourPressureFromRelHumidityMaxMin(double RH_max, double RH_min, double T_max, double T_min)
  
  Actual vapour pressure from maximum and minimum relative humidity Eq. (17)
  
  Parameters:
  
  RH_max - maximum relative humidity [%]
  
  RH_min - minimum relative humidity [%]
  
  T_max - maximum temperature [°C]
  
  T_min - minimum temperature [°C]
  
  Returns:
  
  actual vapour pressure e_a [kPa]
- VapourPressureFromRelHumidityMax
  
  public static double VapourPressureFromRelHumidityMax(double RH_max, double T_min)
  
  Actual vapour pressure from maximum relative humidity Eq. (18)
  
  Parameters:
  
  RH_max - maximum relative humidity [%]
  
  T_min - minimum temperature [°C]
  
  Returns:
  
  actual vapour pressure e_a [kPa]
- VapourPressureFromRelHumidityMean
  
  public static double VapourPressureFromRelHumidityMean(double RH_mean, double T_max, double T_min)
  
  Actual vapour pressure from mean relative humidity Eq. (19)
  
  Parameters:
  
  RH_mean - mean relative humidity [%]
  
  T_max - maximum temperature [°C]
  
  T_min - minimum temperature [°C]
  
  Returns:
  
  actual vapour pressure e_a [kPa]
- EvaporationEquivalentToRadiation
  
  public static double EvaporationEquivalentToRadiation(double Radiation)
  
  Converts radiation [energy/surface] to equivalent evaporation [depth of water] Eq. (20)
  
  Parameters:
  
  Radiation - [MJ m-2 day-1]
  
  Returns:
  
  equivalent evaporation [mm day-1]
- EvaporationEquivalentToRadiation
  
  public static double EvaporationEquivalentToRadiation(double Radiation, double DailyMeanTemperature)
  
  Converts radiation [energy/surface] to equivalent evaporation [depth of water] Correction by daily mean temperature (for 21.18°C it yields a conversion factor of 0.408) See (Harrison)
  
  Parameters:
  
  Radiation - [MJ m-2 day-1]
  
  DailyMeanTemperature - [°C]
  
  Returns:
  
  equivalent evaporation [mm day-1]
- ExtraterrestrialRadiation
  
  public static double ExtraterrestrialRadiation(double d_r, double omega_s, double phi, double delta)
  
  Calculates extraterrestrial radiation Eq. (21)
  
  Parameters:
  
  d_r - inverse relative distance earth-sun
  
  omega_s - sunset hour angle [rad]
  
  phi - latitude [rad]
  
  delta - solar declination [rad]
  
  Returns:
  
  extraterrestrial radiation per day [MJ m-2 day-1]
- DecimalDegreesToRadians
  
  public static double DecimalDegreesToRadians(double degree)
  
  Convert decimal degrees to radians Eq. (22)
  
  Parameters:
  
  degree - [degree]
  
  Returns:
  
  radians [rad]
- InverseRelativeDistanceEarthSun
  
  public static double InverseRelativeDistanceEarthSun(int J)
  
  Inverse relative distance Earth-Sun Eq. (23)
  
  Parameters:
  
  J - number of the day in the year (DOY) [day]
  
  Returns:
  
  inverse relative distance d_r []
- SolarDeclination
  
  public static double SolarDeclination(int J)
  
  Solar declination Eq. (24)
  
  Parameters:
  
  J - number of the day in the year (DOY) [day]
  
  Returns:
  
  solar declination delta [rad]
- SunsetHourAngle
  
  public static double SunsetHourAngle(double phi, double delta)
  
  Sunset hour angle Eq. (25)
  
  Parameters:
  
  phi - latitude [rad]
  
  delta - solar declination [rad]
  
  Returns:
  
  sunset hour angle omega_s [rad]
- ExtraterrestrialRadiationDiurnal
  
  public static double ExtraterrestrialRadiationDiurnal(double d_r, double delta, double phi, double omega_1, double omega_2)
  
  Diurnal extraterrestrial radiation Eq. (29(
  
  Parameters:
  
  d_r -
  
  delta -
  
  phi -
  
  omega_1 -
  
  omega_2 -
  
  Returns:
- SolarTimeAngleBeginning
  
  public static double SolarTimeAngleBeginning(double t_l, double omega)
  
  Solar time angle at beginning of period Eq. (29)
  
  Parameters:
  
  t_l - length of calculation period [h]
  
  omega - solar time angel at midpoint of hourly or shorter period [rad]
  
  Returns:
  
  solar time angle at beginning omega_1 [rad]
- SolarTimeAngleEnd
  
  public static double SolarTimeAngleEnd(double t_l, double omega)
  
  Solar time angle at end of period Eq. (30)
  
  Parameters:
  
  t_l - length of calculation period [h]
  
  omega - solar time angel at midpoint of hourly or shorter period [rad]
  
  Returns:
  
  solar time angle at end omega_2 [rad]
- SolarTimeAngleMidpoint
  
  public static double SolarTimeAngleMidpoint(double t, double L_z, double L_m, double S_c)
  
  Solar time angel at midpoint of period Eq. (31)
  
  Parameters:
  
  t - standard clock time at the midpoint of the period [h]
  
  L_z - longitude of the center of the local time zone [degree]
  
  L_m - longitude of the measurement site [degree]
  
  S_c - seasonal correction for solar time [h]
  
  Returns:
- SeasonalCorrectionSolarTime
  
  public static double SeasonalCorrectionSolarTime(int J)
  
  Seasonal correction for solar time Eq. (32) and (33) *
  
  Parameters:
  
  J - day of year
  
  Returns:
  
  seasonal correction S_c [hour]
- DaylightHours
  
  public static double DaylightHours(double omega_s)
  
  Dayligth hours Eq. (34)
  
  Parameters:
  
  omega_s - sunset hour angle [rad]
  
  Returns:
  
  daylight hours N
- SolarRadiation
  
  public static double SolarRadiation(double R_a, double n, double N, double a_s, double b_s)
  
  Calculates Solar Radiation from sunshine hours Eq. (35)
  
  Parameters:
  
  n - actual duration of sunshine [h]
  
  N - maximum possible duration of sunshine/daylight hours [h]
  
  R_a - extraterrestrial radiation [MJ m-2 day-1]
  
  a_s - regression constant, expressing the fraction of extrater. rad. reaching the earth on overcast day n=0
  
  b_s - regression slope, a_s+b_s is the fraction of extrater. rad. reaching the earth on clear days n=N
  
  Returns:
  
  solar or shortwave radiation R_s [MJ m-2 day-1]
- ClearSkyRadiationWithAngstromVariables
  
  public static double ClearSkyRadiationWithAngstromVariables(double R_a, double a_s, double b_s)
  
  Calculates the clear-sky solar radiation when values for a_s and b_s are available Eq. (36)
  
  Parameters:
  
  R_a - extraterrestrial radiation [MJ m-2 day-1]
  
  a_s - regression constant, expressing the fraction of extrater. rad. reaching the earth on overcast day n=0
  
  b_s - regression slope, a_s+b_s is the fraction of extrater. rad. reaching the earth on clear days n=N
  
  Returns:
  
  Clear-sky solar radiation R_so when N=n [MJ m-2 day-1]
- ClearSkyRadiation
  
  public static double ClearSkyRadiation(double R_a, double z)
  
  Calculates the clear-sky solar radiation when values for a_s and b_s are not available Eq. (37)
  
  Parameters:
  
  R_a - extraterrestrial radiation [MJ m-2 day-1]
  
  z - elevation above sea level [m]
  
  Returns:
  
  Clear-sky solar radiation R_so when N=n [MJ m-2 day-1]
- NetShortwaveRadiation
  
  public static double NetShortwaveRadiation(double R_s, double alpha)
  
  Net solar or net shortwave radiation Eq. (38) Calculates the amount of solar radiation that is not reflected.
  
  Parameters:
  
  incoming - solar radiation [MJ m-2 day-1]
  
  alpha - albedo or canopy reflection coefficient []
  
  Returns:
  
  net shortwave radiation R_ns [MJ m-2 day-1]
- NetSolarRadiation
  
  public static double NetSolarRadiation(double R_s)
  
  Net shortvawe radiation resulting from balance of incoming and reflected solar radiation Eq. (38) Calculates the amount of solar radiation that is not reflected. Albedo coefficient alpha is 0.23 for the hypothetical grass reference crop.
  
  Parameters:
  
  R_s - incoming solar radiation [MJ m-2 day-1]
  
  Returns:
  
  net solar or net shortwave radiation R_ns [MJ m-2 day-1]
- NetLongwaveRadiation
  
  public static double NetLongwaveRadiation(double R_s, double R_so, double e_a, double T_max, double T_min)
  
  Net longwave radiation Eq. (39)
  
  Parameters:
  
  R_s - solar or shortwave radiation [MJ m-2 day-1]
  
  R_so - Clear-sky solar radiation when N=n [MJ m-2 day-1]
  
  e_a - actual vapour pressure [kPa]
  
  T_max - maximum of day temperature [°C]
  
  T_min - minimum of day temperature [°C]
  
  Returns:
  
  net longwave radiation R_nl [MJ m-2 day-1]
- NetLongwaveRadiationHourly
  
  public static double NetLongwaveRadiationHourly(double R_s, double R_so, double e_a, double T)
  
  Net longwave radiation Eq. (39) hourly
  
  Parameters:
  
  R_s - solar or shortwave radiation [MJ m-2 hour-1]
  
  R_so - Clear-sky solar radiation when N=n [MJ m-2 hour-1]
  
  e_a - actual vapour pressure [kPa]
  
  T - temperature [°C]
  
  Returns:
  
  net longwave radiation R_nl [MJ m-2 hour-1]
- NetRadiation
  
  public static double NetRadiation(double R_ns, double R_nl)
  
  Net radiation (difference between incoming shortwave and outgoing longwave radiation) Eq. (40) Remark: equation works also for hourly values. When R_ns and R_nl are in [MJ m-2 hour-1], the resulting net radiation R_n is also in [MJ m-2 hour-1]
  
  Parameters:
  
  R_ns - net solar radiation [MJ m-2 day-1]
  
  R_nl - net longwave radiation [MJ m-2 day-1]
  
  Returns:
  
  net radiation R_n [MJ m-2 day-1]
- SoilHeatFluxHourlyDaylight
  
  public static double SoilHeatFluxHourlyDaylight(double R_n)
  
  Soil heat flux for hourly periods during daylight periods Eq. (45)
  
  Parameters:
  
  R_n - [MJ m-2 hour-1]
  
  Returns:
  
  hourly soil heat flux G_hr [MJ m-2 hour-1]
- SoilHeatFluxHourlyNighttime
  
  public static double SoilHeatFluxHourlyNighttime(double R_n)
  
  Soil heat flux for hourly periods during nighttime periods Eq. (46)
  
  Parameters:
  
  R_n - [MJ m-2 hour-1]
  
  Returns:
  
  hourly soil heat flux G_hr [MJ m-2 hour-1]
- SoilHeatFluxHourly
  
  public static double SoilHeatFluxHourly(double t, double daylen, double R_n)
  
  Soil heat flux for hourly periods Eq. (46)
  
  Parameters:
  
  t - center of the time interval
  
  daylen - daylength
  
  R_n - [MJ m-2 hour-1]
  
  Returns:
  
  hourly soil heat flux G_hr [MJ m-2 hour-1]
- SolarRadiationFromExtraterrestrialRadiationAndTemp
  
  public static double SolarRadiationFromExtraterrestrialRadiationAndTemp(double R_a, double T_max, double T_min, double k_Rs)
  
  Estimates solar radiation by extraterrestrial radiation and temperature Eq. (50)
  
  Parameters:
  
  R_a - extraterrestrial radiation [MJ m-2 day-1]
  
  T_max - maximum of day temperature [°C]
  
  T_min - minimum of day temperature [°C]
  
  k_Rs - adjustment coefficient between 0.16 (interior locations) and 0.19 (coastal locations) [°C-.5]
  
  Returns:
  
  solar radiation R_s [MJ m-2 day-1]
- ReferenceEvapoTranspirationByExtraterrestrialRadiation
  
  public static double ReferenceEvapoTranspirationByExtraterrestrialRadiation(double R_a, double T_max, double T_min)
  
  Estimates the reference evapo transpiration by extraterrestrial radiation and temperature Eq. (52)
  
  Parameters:
  
  R_a - extraterrestrial radiation (evaporation equivalent) [mm day-1]
  
  T_max - maximum of day temperature [°C]
  
  T_min - minimum of day temperature [°C]
  
  Returns:
  
  ET0 crop reference evapotranspiration ET0 [mm day-1]
- ReferenceEvapoTranspirationFromSolarRadiation
  
  public static double ReferenceEvapoTranspirationFromSolarRadiation(double R_s, double T_max, double T_min)
  
  Estimates the reference evapotranspiration by solar radiation and temperature Eq. (52) & Eq. (50) with k_Rs=0.17 see: Hargreaves, Allen, 2003, History and Evaluation of Hargreaves Evapotranspiration Equation: Eq. (3)
  
  Parameters:
  
  R_s - solar radiation (evaporation equivalent) [mm day-1]
  
  T_max - maximum of day temperature [°C]
  
  T_min - minimum of day temperature [°C]
  
  Returns:
  
  ET0 crop reference evapotranspiration ET0 [mm day-1]
- ReferenceEvapoTranspirationHourly
  
  public static double ReferenceEvapoTranspirationHourly(double R_n, double G, double T_hr, double Delta, double gamma, double e_0, double e_a, double u2)
  
  Calculates hourly reference evapotranspiration Eq. (53)
  
  Parameters:
  
  R_n - net radiation at the grass surface [MJ m-2 hour-1]
  
  G - soil heat flux density [MJ m-2 hour-1]
  
  T_hr - mean hourly air temperature [°C]
  
  Delta - saturation slope vapour pressure curve at T_hr [kPa °C-1]
  
  gamma - psychrometric constant [kPa °C-1]
  
  e_0 - saturation vapour pressure at air temperature T_hr [kPa]
  
  e_a - average hourly actual vapour pressure [kPa]
  
  u2 - average hourly wind speed [m s-1]
  
  Returns:
  
  reference evapotranspiration ET_0 [mm h-1]
- ActualVapourPressureFromRelativeHumidityHourly
  
  public static double ActualVapourPressureFromRelativeHumidityHourly(double e_0, double RH_hr)
  
  Estimates hourly actual vapour pressure from hourly relative humidity Eq. (54)
  
  Parameters:
  
  e_0 -
  
  RH_hr -
  
  Returns:
- AdjustedKCoefficientToWindAndHumidity
  
  public static double AdjustedKCoefficientToWindAndHumidity(double K_c, double u2, double RH_min, double h)
  
  Adjustment of coefficient in climates where RH_min differs from 45% or where u2 is larger or smaller than 2 m/s Eq. (62) Same formula is used to adjust K_cmid [Eq. (62)], K_cend [Eq. (65)], K_cb [Eq. (70)], K_cmax [Eq. (72)], K_cbfull [Eq. (99)]
  
  Parameters:
  
  K_c -
  
  u2 -
  
  RH_min -
  
  h -
  
  Returns:
  
  K_c adjusted coefficient
- UpperLimitKCoefficient
  
  public static double UpperLimitKCoefficient(double K_cb, double u2, double RH_min, double h)
  
  Upper limit on the evaporation and transpiration from any cropped surface Eq. (72)
  
  Parameters:
  
  K_cb - basal crop coefficient
  
  u2 - mean value for daily wind speed at 2m height over grass during calculation period [m s-1]
  
  RH_min - mean value for daily minimum relative humidity during calculation period [%]
  
  h - mean maximum plant height during the period of calculation [m]
  
  Returns:
  
  K_cmax upper limit
- ExposedAndWettedSoilFraction
  
  public static double ExposedAndWettedSoilFraction(double f_c, double f_w)
  
  Exposed and wetted soil fraction Eq. (75)
  
  Parameters:
  
  f_c - average fraction of soil covered (or shaded by vegetation)
  
  f_w - average fraction of soil wetted by irrigation or precipitation
  
  Returns:
  
  f_ew exposed and wetted soil fraction
- VegetationCoveredSoilFraction
  
  public static double VegetationCoveredSoilFraction(double K_cb, double K_cmin, double K_cmax, double h)
  
  Effective fraction of soil covered by vegetation Eq. (76)
  
  Parameters:
  
  K_cb - basal crop coefficient for particular day
  
  K_cmin - minimum K_c for dry bare soil with no ground cover
  
  K_cmax - maximum K_c immediately following wetting (Eq. 72)
  
  h - mean plant height [m]
  
  Returns:
  
  f_c effective fraction of soil covered by vegetation
- KCoefficientByLAI
  
  public static double KCoefficientByLAI(double K_cmin, double K_cbfull, double LAI, double k)
  
  Estimated basal K_cb during the mid-season when plant density is lower than full cover Eq. (97)
  
  Parameters:
  
  K_cmin - minimum K_c for bare soil
  
  K_cbfull - basal K_cb for for vegetation having full ground cover
  
  LAI - actual leaf area index [m-2 m-2]
  
  k - canopy light extinction factor
  
  Returns:
  
  Estimated basal K_cb during the mid-season when plant densitiy is lower than full cover
- KCoefficientByLAI
  
  public static double KCoefficientByLAI(double K_cmin, double K_cbfull, double LAI)
  
  Estimated basal K_cb during the mid-season when plant density is lower than full cover Eq. (97) - assumes a canopy light extiction factor of 0.7
  
  Parameters:
  
  K_cmin - minimum K_c for bare soil
  
  K_cbfull - basal K_cb for for vegetation having full ground cover
  
  LAI - actual leaf area index [m-2 m-2]
  
  Returns:
  
  Estimated basal K_cb during the mid-season when plant densitiy is lower than full cover
- p
  
  public static double p(double nominalDepletion, double ETC)
  
  Calculates the ETC-adjusted depletion fraction/factor p. Table 22, Footnote 2, and last paragraph of p. 162. Limited to 0.1 <= p <= 0.8
  
  Parameters:
  
  nominalDepletion - Unadjusted depletion fraction [-]
  
  ETC - Crop evapotranspiration [mm/day]
  
  Returns:
  
  Adjusted p [-]
- AtmosphericDensity
  
  public static double AtmosphericDensity(double T_Kv, double P)
  
  Calculates atmospheric density Eq. (3-5)
  
  Parameters:
  
  T_Kv - virtual temperature [K]
  
  P - atmospheric pressure [kPa]
  
  Returns:
  
  rho atmospheric density [kg m-3]
- VirtualTemperature
  
  public static double VirtualTemperature(double T_k, double e_a, double P)
  
  Calculates virtual temperature Eq. (3-6)
  
  Parameters:
  
  T_k - absolute temperature [K]
  
  e_a - actual vapour pressure [kPa]
  
  P - atmospheric pressure [kPa]
  
  Returns:
  
  T_Kv virtual temperature [K]

Class EquationsFAO56

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Details

a_s_Default

b_s_Default

albedo

lambda

Constructor Details

EquationsFAO56

Method Details

ReferenceEvapotranspiration

AtmosphericPressure

PsychrometricConstant

SaturationVapourPressureAtTemperature

MeanSaturatedVapourPressure

SlopeOfSaturationVapPressureCurve

VapourPressureFromDewpoint

VapourPressureFromPsychrometricData

VapourPressureFromRelHumidityMaxMin

VapourPressureFromRelHumidityMax

VapourPressureFromRelHumidityMean

EvaporationEquivalentToRadiation

EvaporationEquivalentToRadiation

ExtraterrestrialRadiation

DecimalDegreesToRadians

InverseRelativeDistanceEarthSun

SolarDeclination

SunsetHourAngle

ExtraterrestrialRadiationDiurnal

SolarTimeAngleBeginning

SolarTimeAngleEnd

SolarTimeAngleMidpoint

SeasonalCorrectionSolarTime

DaylightHours

SolarRadiation

ClearSkyRadiationWithAngstromVariables

ClearSkyRadiation

NetShortwaveRadiation

NetSolarRadiation

NetLongwaveRadiation

NetLongwaveRadiationHourly

NetRadiation

SoilHeatFluxHourlyDaylight

SoilHeatFluxHourlyNighttime

SoilHeatFluxHourly

SolarRadiationFromExtraterrestrialRadiationAndTemp

ReferenceEvapoTranspirationByExtraterrestrialRadiation

ReferenceEvapoTranspirationFromSolarRadiation

ReferenceEvapoTranspirationHourly

ActualVapourPressureFromRelativeHumidityHourly

AdjustedKCoefficientToWindAndHumidity

UpperLimitKCoefficient

ExposedAndWettedSoilFraction

VegetationCoveredSoilFraction

KCoefficientByLAI

KCoefficientByLAI

p

AtmosphericDensity

VirtualTemperature