Use of vapor pressure deficit as a parameter in fire spread?

[cjm23]

This would be a potential enhancement, but would it be possible to include VPD as a parameter for fire spread or max fire spread? Some studies have found it useful in explaining wildfire trends in CA (e.g., Williams et al. 2019, 10.1029/2019EF001210).

[rmscheller]

Charles,
It's a good idea. It would need to be optional as not all climate forecasts include daily VPD. Do you know how often it is provided?

[ZacharyRobbins]

Including it as a predictor in the glm of the spread model would allow for it to be optional, it could just be set as 0.00 if you do not include it. I will research this implementation.

[cjm23]

Apologies for not following up sooner about this, the code that I have is passed on from Abatzaglou's calculation of VPD used in gridMET. Because it uses min and max temps and RHs, it's possible to calculate a number of different VPD values (e.g., min-min, max-max, avg-avg, etc.) and I'm not sure what is "best".
calcES <- function(temperatureFilename) {
if (!file.exists(temperatureFilename)) {
return(NULL)
}
temperatureData <- raster(temperatureFilename)
esData <- 6.112 * exp ((17.67 * temperatureData) / (temperatureData + 243.5));
return(esData)
}

  calcVPD <- function(rhData, esData, outputFilename) {
    if (is.null(rhData) || is.null(esData)) {
      return(NULL)
    }
    vpdData <- (esData/10) * (1-rhData/100)
    writeRaster(vpdData, filename=outputFilename,
                format='GTiff', options=c("TILED=YES","COPY_SRC_OVERVIEWS=YES","COMPRESS=LZW"),
                overwrite=T)
    return(vpdData)
  }

[ZacharyRobbins]

Aim for June progress

[ZacharyRobbins]

@rmscheller is VPD in the climate library? I don't mind adding it to spread, but it seems like the calculation should be done there not in the fire submodule.

[rmscheller]

Yes, to the best of my knowledge, it is an option in the climate library.