[Rnomads-user] Is GribGrab's model.domain option working at all??

[aakremena at aol.com]

Hi rNOMADS users,

Setup:
     -- I'm playing with rNOMADS (started with rNOMADS yesterday).  
     -- Most likely I should be doing something wrong here but what concerns me, the GribGrab's 'model.domain' option is not kicking in...
     -- Here is some sample code:

rm(list = ls())
library(rNOMADS)

#A location near my house
lat <- 35.828304
lon <- -79.107467

#Get nearest model nodes
lons <- seq(0, 359.5, by = 0.5)
lats <- seq(-90, 90, by = 0.5)
lon.diff <- abs(lon + 360 - lons)
lat.diff <- abs(lat - lats)
model.lon.ind <- which(lon.diff == min(lon.diff)) - 1 #NOMADS indexes at 0
model.lat.ind <- which(lat.diff == min(lat.diff)) - 1 
model_domain <- c(model.lon.ind, model.lon.ind, model.lat.ind, model.lat.ind)

#Find the latest Global Forecast System model run
urls.out <- CrawlModels(abbrev = "gfs_0p50", depth = 2)
urls.out <- gsub("gfs_0p50", "gfs_0p25_1hr", urls.out)  #this is meant to avoid the error coming from using  CrawlModels(abbrev = "gfs_0p25_1hr", depth = 2) 

latest.model <- urls.out[1]
model.parameters <- ParseModelPage(latest.model)
pred.ind <- c(3,4,5)  #use only 3 temperature forecasts

variables <- c("TMP")
levels <- c("2 m above ground")
grib.info <- GribGrab(urls.out[1], model.parameters$pred[pred.ind], levels, variables, model.domain = model_domain)
grib.data <- ReadGrib(grib.info[[1]]$file.name, levels, variables, domain = model_domain) 

Observations:
1. The region I need temperatures for is a single geographic point:
         model_domain <- c(562, 562, 252, 252)

2. Still, GribGrab produces in this case 3 downloaded .grb files, each 1.4 MB, which seems a lot for a single temperature data point inside each one.

3. The length of grib.data[[7]] is 1038240, which again confirms that GribGrabd is downloading temperatures for the whole world and not for the single geographic point with (lat, lon), given above.

Questions:
    A. Am I doing anything wrong here, or the model.domain option is somehow, permanently set to NULL??

    B. More generally, how can I download data only for a specified location, so that not to burden unnecessarily the NOMADS server?

Thank you in advance.

Anguel


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