Hi there,

I am currently working on a project that involves climate model data stored in a NetCDF file. I am currently trying to calculate "weighted" spatial annual "global" averages for precipitation. I need to do this for each of the 95 years of global precipitation data that I have. The idea would be to somehow apply weights to each grid cell by using the cosine of its latitude (which means latitude grid cells at the equator would have a weight of 1 (i.e. the cosine of 0 degrees is 1), and the poles would have a value of 1 (as the cosine of 90 is 1)). Then, I would be in a position to calculate annual weighted averages based on averaging each grid cell.

I have an idea how to do this conceptually, but I am not sure where to begin writing a script in R to apply the weights across all grid cells and then average these for each of the 95 years. I would greatly appreciate any help with this, or any resources that may be helpful!!!

At the very least, I have opened the .nc file and read-in the NetCDF variables, as shown below:

ncfname<-"MaxPrecCCCMACanESM2rcp45.nc"

Prec<-raster(ncfname)

print(Prec)

Model<-nc_open(ncfname)

get<-ncvar_get(Model,"onedaymax")longitude<-ncvar_get(Model, "lon")

latitude<-ncvar_get(Model, "lat")

Year<-ncvar_get(Model, "Year")

Also, if it helps, here is what the .nc file contains:

3 variables (excluding dimension variables):

double onedaymax[lon,lat,time] (Contiguous storage)

units: mm/day

double fivedaymax[lon,lat,time] (Contiguous storage)

units: mm/day

short Year[time] (Contiguous storage)

3 dimensions:

time Size:95

lat Size:64

units: degree North

lon Size:128

units: degree East

Again, any assistance would be extremely valuable with this! I look forward to your response!

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