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HMS Smoke Explorer: To visualize NOAA's Hazard Mapping System (HMS) smoke product


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NOAA's Hazard Mapping System (HMS) Smoke Product

The HMS Smoke Explorer allows end-users to visualize NOAA's Hazard Mapping System (HMS) smoke product, MODIS active fires and aerosol optical depth, and GOES-East/West RGB imagery. Since 2005, NOAA analysts manually inspect visible imagery (e.g. GOES, MODIS, VIIRS) and outline the extent of smoke across North America, classified into three density categories: light, medium, and heavy, to produce the HMS smoke product.

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Tool Capabilities

  • Make an animation looping GOES-East/West RGB imagery. Right-click on the GIF and select "Save Image As..." to save the animation to your local storage.
  • View satellite-derived (MODIS) and model forecast (CAMS) aerosol optical depth and surface PM2.5 with HMS smoke.
  • View HMS smoke text descriptions and summary statistics.


Dataset Time Range Spatial Resolution
HMS Smoke 2005/08-present --
FIRMS/MODIS Active Fires 2000/10-present 1 km
MODIS Burned Area 2000/10-present 500 m
MODIS MAIAC Aerosol Optical Depth (AOD) 2000/02-present 1 km
ECMWF/CAMS AOD, PM2.5 2016/06-present 0.4°
GOES-16/East 2017/07-present 2 km
GOES-17/West 2018/12-2023/01 2 km
GOES-18/West 2022/10-present 2 km


The processed HMS smoke product can be used for analysis on Earth Engine (EE) and downloaded as yearly files.

// read HMS polygons by year
var inYear = 2020;
var HMS = ee.FeatureCollection('projects/GlobalFires/HMS/HMS_' + inYear);

// filter by month and day
var inMonth = 8;
var inDay = 1;
var HMSday = HMS.filter(ee.Filter.eq('Month',8)).filter(ee.Filter.eq('Day',1));

Variable Description Format
ID Unique ID for each polygon YYYYJJJ (1-4 = year, 5-7 = day of year, 8-11 = original row of a polygon in that day's raw HMS file)
Year Year 2005-present
Month Month 1-12
Day Day 1-31
JDay Julian day or DOY 1-365
Start Start time HHMM
End End time HHMM
StSec Start time seconds since 1970-01-01
EndSec End time seconds since 1970-01-01
Duration End time minus start time, with a 15-min buffer hours
Density Density of smoke polygon 'Light', 'Medium', 'Heavy', or 'Unspecified'
Satellite Satellite used as a reference for the polygon e.g., 'GOES-EAST', 'GOES-WEST'
Area Area of polygon km2
QAFlag QA flag 0-5 (valid: 0 = good, 1 = coordinates adjusted, 2 = unclosed rings; invalid and not included in SHP: 3 = linestring, 4 = point / empty, 5 = crossed edges)
IsMulti Is the polygon a multipolygon? 'Y' or 'N'
fillFlag* Flag on gap-filling smoke density 0 = no gapfill, 1 = gapfill (model with AOD), 2 = gapfill (model without AOD)
fillConf* Confidence on gap-filled density based on predicted model outcomes from bootstrapping (polygons that did not need gap-filling are automatically labeled with a value of 1) 0-1

* only relevant for 2005-2010, so HMS files for only those years have these columns on EE


  • The start and end time represent the time bounds of the satellite images used to draw the HMS polygons, not the actual persistence duration of the smoke plume
  • In the tool, duration is used to estimate the annual contribution of each smoke density category at a particular location
  • For QA = 1, out-of-bounds coordinates with y > 90 or y < -90 are removed (removes some anomalous coordinates), x < -180 is forced to be x = -180 as this may lead to disfigured polygons on EE
  • For QA = 2, the first coordinate is repeated at the end of the list of coordinates to close the polygon ring


  • The HMS smoke product represents smoke as seen from satellites. In some places, smoke may be aloft and may not affect surface air quality. This is particularly true for light smoke.
  • Use caution when assessing trends in smoke using the HMS smoke product outside of CONUS. Note the lower spatial coverage in earlier years, which can be seen from the artificial boundaries in annual aggregates.
  • The HMS 'Duration' is calculated from the start and end times of satellite images used to outline the smoke. Thus, it is not an estimate of the true smoke duration. HMS analysts outline smoke using only daytime satellite imagery and generally analyze heavy smoke twice per day in the morning and late afternoon.
  • HMS smoke polygons in 2005-2007, 2009, and some in 2008 and 2010 are not classified into smoke density classes (light, medium, heavy). We used random forest modeling to assign densities to all such polygons.
  • HMS smoke polygons with bad geometries and throws an error in R (i.e. drawn as lines rather than polygons, edges crossing edges) have been removed.
  • GOES-16/East became operational on December 18, 2017, GOES-17/West on February 12, 2019, and GOES-18/West on January 4, 2023 (replacing GOES-17/West). Note these dates when selecting the GOES RGB images.

HMS Quality Control

Number of HMS polygons in each year, and how many are invalid after processing in R (up to Jan 18, 2024). The number of smoke polygons with gapfilled densities are also shown below.

Year Total Valid Invalid Gapfill
2005 6296 6291 5 6291
2006 15453 15441 12 15441
2007 19881 19870 11 19612
2008 23203 23186 17 5073
2009 23517 23480 37 23332
2010 27241 27215 26 7437
2011 33721 33704 17 0
2012 27972 27964 8 0
2013 23162 23143 19 0
2014 18565 18557 8 0
2015 16356 16344 12 0
2016 21280 21268 12 0
2017 25843 25841 2 0
2018 41331 41320 11 0
2019 42945 42934 11 0
2020 45440 45438 2 0
2021 27573 27572 1 0
2022 21906 21904 2 0
2023 20303 20302 1 0
2024 235 235 0 0

Gap-filling Unspecified Densities

We used random forest classification to assign densities (light, medium, or heavy) to polygons with unspecified densities from 2005-2010. This procedure is described in Liu et al. (in review). Note that the code has recently been updated to use sf instead of rgdal, and additional processing has been done to fix more bad geometries. The code workflow uses EE to generate some input data for the random forest model (HMS_Stack.js,HMS_AOD.js). The rest of the workflow is in R with RFmodel_prepare.R to output a CSV table of data for all HMS polygons from 2005-2022, RFmodel_withAOD.R and RFmodel_withoutAOD.R to run the random forest classification models, RFmodel_export.R to output another CSV table now with the gap-filled densities, and finally HMS_gapfill_shp.R to rewrite HMS files from 2005-2010 with the gap-filled densities and associated flags.


  • September 2023: uploaded gap-filled HMS polygons from 2005-2010 and added related code; added ancillary code for preprocessing; added note about evaluation of the HMS smoke product in app
  • July 2023: updated R code to process HMS from rgdal to sf, code is now more inclusive of out-of-bounds polygons and attempts to fix some bad geometries (unclosed rings and out-of-bounds coordinates) but excludes polygons with crossed edges as sf cannot fix them; added QA flags; added jump to latest button
  • September 2020: added option to select GOES-East or GOES-West full disk imagery, added CAMS PM2.5 and AOD
  • August 2020: added visualization of GOES RGB imagery, HMS smoke days and 'duration'


Liu, T., F.M. Panday, M.C. Caine, M. Kelp, D.C. Pendergrass, and L.J. Mickley. Is the smoke aloft? Caveats regarding the use of the Hazard Mapping System (HMS) smoke product as a proxy for surface smoke presence across the United States. (in review, preprint:


HMS Smoke Explorer: To visualize NOAA's Hazard Mapping System (HMS) smoke product