Description Usage Arguments Details Value References Examples
download_data
is the main function to download a scene given the correct tile, date and satellite.
get_tile
is a helper function that actually downloads a tile. Supplied with a correct ftp
address and tile
the function downloads the MODIS tile, and transforms the coordinate reference system to latlong (EPSG:4326).
1 2 3 4 |
date |
Day for which snow data should be downloaded as |
sat |
Satellite mission used. Currently Terra ( |
h |
Horizontal tile number, see also details. |
v |
Vertical tile number, see also details. |
printFTP |
If |
... |
Further arguments passed to |
ftp |
Address of the repository. |
tile |
Name of the tile. |
progress |
Indicates whether or not progress is displayed. |
clean |
Indidcates whether or not temporary files are deleted. |
When downloading the data, the correct tile has to be specified. At the moment there is no automated way to find the tile. This means that the user has to consult the MODIS land grid to find the correct tile. Alternatively the MODIS tile calculator may be used.
The function returns an object of the class RasterLayer
with the following cell values:
0-100 NDSI snow cover
200 missing data
201 no decision
211 night
237 inland water
239 ocean
250 cloud
254 detector saturated
255 fill
but see also the documentation for the NDSI_SNOW_COVER here.
When using the MODIS snow cover data, please acknowledge the data appropriately by
reading the use and copyright
citing the original data: Hall, D. K. and G. A. Riggs. 2016. MODIS/[Terra/Aqua] Snow Cover Daily L3 Global 500m Grid, Version 6. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/MODIS/MOD10A1.006. [Date Accessed].
1 2 3 4 5 6 7 | ## Not run:
# Download MODIS snow data for a central europe h = 18 and v = 5 for the 1 of January 2016
dat <- download_data(lubridate::ymd("2016-01-01"), h = 18, v = 5)
class(dat)
raster::plot(dat)
## End(Not run)
|
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