require(ncdf4)

# to get all the future filenames:
filenames <- list.files(path="G:/future",pattern="_.....nc", full.names=TRUE,recursive=T)
# just change to path for the "present" ones

# let's run this for just one file:
fn <- filenames[1]

# load one of the roms files
roms <- nc_open(fn)

# to see what's in the roms file:
print(roms)

# load temperature
temp <- ncvar_get(roms,"temp")
dim(temp)

# load lat & long
lon <- ncvar_get(roms,"lon_rho")
lat <- ncvar_get(roms,"lat_rho")

# load depth
depth <- ncvar_get(roms,'h')

# load mask (land or sea)
mask <- ncvar_get(roms,"mask_rho")

# load time
ocean_time <- ncvar_get(roms,varid = 'ocean_time')
base_time <- "2060-01-01"  # use this for "future" ROMS files
# base_time <- "1990-01-01"  # use this for "present" ROMS files
ocean_time <- as.POSIXct(unlist(ocean_time), origin = base_time)