Vapour pressure deficit (VPD)

Vapour pressure deficit (VPD) was computed with REddyProc in \(hPa\) from relative humidity in \(\%\) and air temperature in \(^{\circ}C\).

VPD0 <- fCalcVPDfromRHandTair(DEGebExample$rH, DEGebExample$Tair)

bigleaf package computes VPD in \(kPa\) and requires relative humidity as fraction .

VPD.hPa <- rH.to.VPD(DEGebExample$rH/100, DEGebExample$Tair)*10

Saturation vapor pressure (SVP) or eSat in \(hPa\) was computed from air temperature.

Tair <- seq(10,25,by = 5)

eSat0 <- fCalcSVPfromTair(Tair)

is replaced by Esat.slope which uses \(kPa\) as pressure unit:

(eSat <- Esat.slope(Tair)$Esat * 10)

## [1] 12.26030 17.01672 23.32596 31.60057

Actual vapor pressure (AVP) or e in \(hPa\) was also computed from Vapor mole fraction (VMF) in \(mol/mol\) and pressure in \(hPa\).

VMF <- seq(0.01,0.03,by = 0.005)
press.in.hPa <- 1000 

e0 <- fCalcAVPfromVMFandPress(VMF, press.in.hPa)

There is no replacement function, as this is just the multiplication of the two arguments.

(e <- VMF * press.in.hPa)

## [1] 10 15 20 25 30

Relative humidity (rH) in \(\%\) was computed from AVP in \(hPa\) and temperature.

e.in.hPa <- seq(0,30,by = 5)
Tair <- 25           

(rH0 <- fCalcRHfromAVPandTair(e.in.hPa, Tair))

Again this is replaced by a function using pressure units \(kPa\) and relative humidity as fraction.

(rH <- e.to.rH(e.in.hPa/10, Tair)*100)

## [1]  0.0000 15.8225 31.6450 47.4675 63.2900 79.1125 94.9350

Evapotranspiration from latent heat and air temperature

LE <- seq(300,500,by = 50)
Tair <- 25

ET0 <- fCalcETfromLE(LE, Tair)

The corresponding bigleaf function LE.to.ET returns a value in kg/m2/s. This needs to be converted to mmol/m2/s as returned by the former fCalcETfromLE.

ETkg <- LE.to.ET(LE, Tair)
(ETmmol <- kg.to.mol(ETkg)*1000)

## [1]  6.819916  7.956569  9.093222 10.229874 11.366527

Converting visible radiation from irradiance to photons flux

Photon flux density (PPFD) of visible light can be computed from energy in incoming radiation

Rg <- 200

bigleaf function Rg.to.PPFD combines the two former REddyProc functions fConvertVisibleWm2toPhotons and fConvertGlobalToVisible.

PPFDVis0 <- fConvertGlobalToVisible(fConvertVisibleWm2toPhotons(Rg))

(PPFDVis <- Rg.to.PPFD(Rg))

## [1] 460

The PPFD of light including non-visible parts, i.e. former fConvertVisibleWm2toPhotons, is obtained by setting argument frac_PAR to 1.

(PPFDAll <- Rg.to.PPFD(Rg, frac_PAR = 1))

## [1] 920

Potential and Extraterrestrial solar radiation

Potential radiation (\(W m^{-2}\)) depends on time and geo-location.

doy <- 160
hour <- seq(6,18,by = 0.2)
latDeg <- 39.94
longDeg <- -5.77
timezone <- +1

Formerly, REddyProc provided:

(potRad0 <- fCalcPotRadiation(doy, hour, latDeg, longDeg, timezone))

This is replaced by bigleaf:

head(potRad <- potential.radiation(doy, hour, latDeg, longDeg, timezone))

## [1]   1.722378  48.072563  95.193985 142.957488 191.232157 239.885672

Extraterrestrial solar radiation was formerly computed by REddyProc by:

(extRad0 <- fCalcExtRadiation(doy))

This is replaced by bigleaf:

(extRad <- extraterrestrial.radiation(doy))

## [1] 1324.598

Required computation of sun position (computeSunPosition) and difference between apparent local time time and time zone time (computeSolarToLocalTimeDifference) have been moved to package solartime.