The 2018 wildfire season has been one for the record books. Along with historically high numbers of wildfires in the Western U.S. and in Canada, this season included rare wildfires above the Arctic Circle in Scandinavia and near the Russia-Finland border.
Along with the threat to lives and property, these fires also affect local weather. As heat from these fires rises into the atmosphere, it has the potential for producing pyrocumulonimbus, or pyroCb, events. A pyroCb is a fire-caused or fire-enhanced thunderstorm that in its most extreme form pumps high amounts of smoke and other biomass-burning emissions into the lower stratosphere. Smoke and other suspended particles in the atmosphere are known as "aerosols."
A new near real-time product available through NASA’s Land, Atmosphere Near real-time Capability for EOS (LANCE) system makes it easier to track the extent and spread of pyroCb and other high-aerosol events. This is vital information due to the many impacts caused by areas of high aerosol concentrations.
High aerosol concentrations not only can affect climate and reduce visibility, they also can impact breathing, reproduction, the cardiovascular system, and the central nervous system, according to the U.S. Environmental Protection Agency. Since aerosols are able to remain suspended in the atmosphere and be carried in prevailing high-altitude wind streams, they can travel great distances away from their source and their effects can linger.
Fortunately, the global movement of aerosols can be tracked using instruments aboard Earth observing satellites. One of these instruments is the Ozone Mapping and Profiler Suite (OMPS) aboard the joint NASA/National Oceanic and Atmospheric Administration (NOAA) Suomi National Polar-orbiting Partnership (Suomi-NPP), launched in 2011, and NOAA-20 (launched in 2017) satellites.
The primary purpose of OMPS is to provide daily measurements of the global distribution of atmospheric ozone. Ozone is an important molecule in the atmosphere because it partially blocks harmful ultra-violet radiation from the sun. OMPS data help scientists monitor the health of this vital protective layer.
OMPS also can be used to measure concentrations of atmospheric aerosols from dust storms and similar events as well as sulfur dioxide (SO2) from volcanic eruptions. One aerosol-related OMPS product is a value known as the “aerosol index,” or AI. The AI value is related to both the thickness and height of the atmospheric aerosol layer. For most atmospheric events involving aerosols, the AI ranges from 0.0 to 5.0, with 5.0 indicating heavy concentrations of aerosols that could reduce visibilities or impact health.
The AI product from the Suomi-NPP OMPS is produced by the LANCE system. LANCE is part of NASA’s Earth Observing System Data and Information System (EOSDIS), and provides satellite imagery generally within three hours of a satellite observation. While these near real-time images do not have the high level of processing required for use in scientific research, they are valuable tools for tracking and managing ongoing natural events, such as wildfires, volcanic eruptions, and dust storms. The OMPS AI product is available for viewing using NASA's Worldview satellite imagery exploration tool.
Since the AI signal remains below 5.0 for most smoke and dust events, the OMPS AI product with an AI range of 0.0 to 5.0 satisfies the needs of most LANCE users. However, the AI signal for pyroCb events, which are both dense and high in the atmosphere, easily can be much larger than 5.0. In fact, the highest AI value ever observed (55.0) occurred during a pyroCb event in August 2017.
To provide better near real-time imagery for these high AI events, the OMPS and LANCE teams designed a new pyroCb product with an upper AI limit of 50.0. The design team also removed flags that screened out unusually high AI values. The resulting OMPS PyroCumuloNimbus AI product more accurately captures high AI events and makes it easier to track the spread of high aerosol concentrations in the atmosphere.
See for yourself, and use Worldview and the OMPS AI and PyroCumuloNimbus AI products to explore and track global high-aerosol events!