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MODIS satellite data

See the NASA Ocean Color website for more information on the MODIS Aqua and Terra instruments. So far, only a small subset of the available data products can be accessed using dreamcoat, but this will be improved in future versions.

Set up credentials

You need to create a NASA Earthdata account in order to download MODIS data.

Create a .netrc file and generate an AppKey as described here (check the Download Methods tab on that page). Put the appkey in ~/.dreamcoat/nasa_appkey.dat.

The download functions use wget, so they won't work natively on Windows.

Download dataset

Dreamcoat downloads the daily L3-mapped observations from MODIS Aqua and Terra and combines them into a single dataset for each day, taking the mean of the two instruments. To get a day or some consecutive days of data, use get_days():

import dreamcoat as dc

modis = dc.modis.get_days(
    date_min=None,
    date_max=None,
    latitude_min=-90,
    latitude_max=90,
    longitude_min=-180,
    longitude_max=180,
    appkey=None,
    delete_nc=False,
    filepath=".",
    resolution="9km",
)
  • Dates should be given in %Y-%m-%d format. If left blank, yesterday is used for both.
  • Resolution can be "4km" or "9km".
  • Files are downloaded as netCDFs into the filepath.

Only particulate inorganic carbon (PIC) data are downloaded. These data are in mol/m3.

Open daily datasets

To open a sequence of already-downloaded daily datasets and combine them into a single xarray Dataset, use open_days():

modis = dc.modis.open_days(
    date_min="1900-01-01",
    date_max="2300-01-01",
    filepath=".",
)