Image masks of global ship tracks for NASA MODIS data products

This dataset provides hand-labeled data rasters of ship tracks (long thin artificial cloud features formed by ship exhaust) observed from NASA's MODIS AQUA satellite imager between 2006-2007, using the L2-"Atmospheric Corrected Reflectance" data product obtained at the 2.1 micrometer radiance band.

In the dataset, we provide:

- Full_Sized_Images - a directory containing full sized images of the Raw data (raw images) which are directly plotted from the raw data in terms of the Atmospherically Corrected Radiance product at the 2.1 micrometer spectral band, and Masked Images which are the raw data masked by pixels (rasters) which we have labeled as ship tracks.

- Padded_Images - a directory containing the same images as before, but this time padded by width and height for future Machine Learning applicability. In addition, faded images are available, which highlights ship track pixels in the raw image at a relative higher pixel intensity.

- Projected_Images – a directory which contains rectangular latitude/longitude projected images from the coordinates of the NASA swath that obtained the data. Missing values are either interpolated with respect to the rest of the image (Projected_interpolatation), or imputed with the non-missing minimum pixel intensity seen in each image (Projected_min).

-Swath_Images – a directory which contains the swath projected raw images on non-uniform grid, with missing values imputed by the image minimum

-heads.json - A single JSON file containing automatically derived “head” information for each identified ship track. The JSON is structured as a nested dictionary keyed by the image date/time (e.g., "2006166.1845"). Each key holds a dictionary of track indices (e.g., "0", "1", etc.), where each track has:

• head_lat and head_lon: The latitude/longitude location of the identified track head.
• head_angle: The direction (in degrees) of the track, measured relative to North (0°).
• wind_angle: The estimated local wind direction (in degrees) at the same altitude, derived from ERA5 reanalysis.
  In some cases, the head angle or wind angle may be set to NaN if it could not be reliably determined.

The naming of the files within each directory follows the convention YearDay-Time-Category.png which is inherited from the NASA Earth Data repository where the raw satellite data files are hosted (https://www.earthdata.nasa.gov/), where category is either Raw or Masked, corresponding to the raw reflectance images and ship tracks rasters, respectively.