LightningCast output is produced for several satellites (e.g., GOES-16, GOES-18) over several sectors (e.g., CONUS, Mesoscale1, Mesoscale2), in several formats (e.g., netCDF4, json). This page briefly describes these formats.

netCDF4

LightningCast data are re-projected from the native geostationary projection to a Plate carrée projection in order to conform to a requirement in the AWIPS resource that LightningCast utilizes for NOAA's NWS.

Here is an example file: LightningCast_GOES-16_RadC_20230901-174617.nc

• GOES-16 is the satellite
• RadC is the sector (RadC is for the CONUS sector; RadM1 and RadM2 are Mesoscale sectors)
• 20230901-174617 is the start time of the GOES-R satellite scan.

Files from the University of Wisconsin may have the prefix UWSSEC_AWIPS_.

This is what the header looks like in an example netCDF4:

netcdf LightningCast_GOES-16_RadC_20230901-174617 {
dimensions:
	x = 1050 ;
	y = 610 ;
variables:
	float PLTG_60min(y, x) ;
		PLTG_60min:units = "%" ;
		PLTG_60min:long_name = "Probability of lightning in the next 60 min" ;
		PLTG_60min:missing_value = -100.f ;
	float PLTG_60min_plax(y, x) ;
		PLTG_60min_plax:units = "%" ;
		PLTG_60min_plax:long_name = "Probability of lightning in the next 60 min" ;
		PLTG_60min_plax:missing_value = -100.f ;
		PLTG_60min_plax:parallax_cloud_height_in_m = 9000LL ;

// global attributes:
		:title = "NOAA/CIMSS LightningCast" ;
		:satellite = "GOES-16" ;
		:sector = "RadC" ;
		:orbital_slot = "GOES-East" ;
		:sector_id = "ECONUS" ;
		:time_coverage_start = "20230901-174617 UTC" ;
		:file_created_time = "20230901-174941 UTC" ;
		:model = "/home/jcintineo/lightningcast/src//static//fit_conv_model.h5" ;
		:NWlat = 55LL ;
		:NWlon = -135LL ;
		:dx = 0.1 ;
		:dy = 0.1 ;
}

The extent of the covered domain is defined by the dimensions x (number of lons) and y (number of lats), the global attributes for the northwest corner point NWlat and NWlon, and the global attributes for spacing between points dx and dy.

The two variables are very similar. The only difference is that PLTG_60min_plax is parallax-corrected using a constant cloud-height assumption based on the attribute variable parallax_cloud_height_in_m.

geoJSON

The geoJSON format for LightningCast is quite simple. Here is an example filename:

PLTGGOESEastRadC_20230901_180117.force.json

• PLTG stands for "probability of lightning".
• GOESEast (or GOESWest) is the slot of the observing satellite
• RadC (or RadM1, RadM2, RadF) is the sector name
• 20230901_180117 is the timestamp

Each file has a few global attributes:

• "source": "NOAA ProbSevere"
• "product": "LightningCast - P(LTG) in 60 min"
• "validTime": "20230901_180117 UTC"
• "productionTime": "20230901_180428 UTC"
• "type": "FeatureCollection"

Each feature in the geoJSON is for a discrete probability level (e.g., 10%, 25%, 50%, 75%) and has a geometry of type "LineString" or "Polygon", with "coordinates" in lon-lat space.

For a "Polygon" for example: "type": "Polygon", "coordinates": [[[-87.776, 49.188], [-87.799, 49.088], [-87.715, 48.946] ... [-87.776, 49.188]]]

Finally, there are several "properties" for each features:

• "OPACITY": "0" #opacity to fill the contour level
• "BOPACITY": "100" #opacity of the boundary of the LineString or Polygon
• "COLOR": "0 0 255" #R-G-B triplet for the fill color of the contour
• "BCOLOR": "0 0 255" #R-G-B triplet for the boundary color of the contour
• "WIDTH": "1" #width of the contour
• "INFO": "PLTG: 10%" #extra information. "PLTG: 10%" means this is a 10% probability of lightning contour