Tiles are specified by a resolution, northing, and westing; northing and westing refer to the
northwest corner of each NED tile, in degrees; tiles are 1x1 degree.
Tiles are downloaded in zipped ESRI ArcGrid format. downloadNED
returns the path to the downloaded zip file.
download_ned_tile(res = "1", tileNorthing, tileWesting, raw.dir)
A character string representing the full local path of the downloaded directory.
A character string representing the desired resolution of the NED. '1' indicates the 1 arc-second NED (the default), while '13' indicates the 1/3 arc-second dataset.
An integer representing the northing (latitude, in degrees north of the equator) of the northwest corner of the tile to be downloaded.
An integer representing the westing (longitude, in degrees west of the prime meridian) of the northwest corner of the tile to be downloaded.
A character string indicating where raw downloaded files should be put. The directory will be created if missing. Defaults to './RAW/NED/'.