match_ersem_temp: Match ERSEM temperature to biotic observations
In remsamp/Rmerp_public:

This functions uses ERSEM sea surface temperature and matches it to a user-provided data set of geolocated observations. The ERSEM data set is not included in the package but can be downloaded freely from opec website at https://portal.marineopec.eu/ (see example on how to load the data into R). This is montly data between jan 1991 and november 2013 on a lattice covering a domain between longitudes -19.83333 and 13.00000 and latitudes 40.11111 and 64.88889.

1	match_ersem_temp(ersem = NULL, lon, lat, year, month)

`ersem`	is the data set containing the ersem temperature data
`lon`	is the longitude for the observation to match
`lat`	is the latitude for the observation to match
`year`	is the year the observation was recorded
`month`	is the month the observation was recorded

# Not run: download ersem netcdf4 file and split it 
# by months (275 between jan 1991 and nov 2013)
#library(netcdf4)
#netc_ersem <- nc_open("path_to_ersem_netcdf4_file.nc")
#myersem <- vector("list", length = dim(netc_ersem)[1])
#for(i in 1:length(myersem)) myersem[[i]] <- netc_ersem[i, , ] 
#match_ersem_temp(ersem = myersem, lon = -7, lat = 50, year = 2010, month = 8)