The local impacts of the Australian bushfires have been devastating to property and life in Australia while producing extreme air quality impacts throughout the region. As smoke from the massive fires has interacted with the global weather, the transport of smoke plumes around the global have accelerated through deep vertical transport into the upper troposphere and even the lowermost stratosphere, leading to long-range transport around the globe. The smoke from these bushfires will travel across the Southern Ocean completing a global circumnavigation back around to Australia and is particularly pronounced across the southern Pacific Ocean out to South America.
The animation shows RGB color images from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua satellite for December 31, 2019 through January 5, 2020. A plume of brown smoke extends from the southeastern coast of Australia, over the Tasman Sea and beyond into the Pacific Ocean.
The overlaid vertical cross sections show CALIPSO lidar observations for these same days. The bright colors indicate the presence of small particles (aerosols) and the white color indicates clouds. Visible in each of the cross sections near 40 degrees south is a thick layer of smoke from the fires at altitudes above 9 miles (14.5 km). The dark shading below these layers is due to the absence of lidar signals below the opaque smoke layers. These layers contain very small particles and have optical properties similar to smoke.
The sequence of CALIPSO and MODIS tracks in the animation indicates the continued transport of the smoke layer to the east. As of Jan. 5, 2020, smoke was detected more than 4,000 miles from the source.
Since 2008, the USDA’s National Agricultural Statistics Service, or NASS, has drawn on Landsat data to monitor dozens of crops in the lower 48 states as part of NASS’s Cropland Data Layer program. The Cropland Data layer uses Landsat and similar sensors to identify what crop is growing where in the country. Separately, NASS uses NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the Aqua and Terra satellites to monitor daily vegetation health and growth stage, all indicators of crop yield.
Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth’s atmosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth’s polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. In 2019, NASA announced the “ozone hole” was the smallest ever since it was first discovered in 1982.
The main cause of ozone depletion and the ozone hole is manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds are transported into the stratosphere by turbulent mixing after being emitted from the surface, mixing much faster than the molecules can settle. Once in the stratosphere, they release halogen atoms through photodissociation, which catalyze the breakdown of ozone (O3) into oxygen (O2). Both types of ozone depletion were observed to increase as emissions of halocarbons increased.
Ozone depletion and the ozone hole have generated worldwide concern over increased cancer risks and other negative effects. The ozone layer prevents most harmful UV wavelengths of ultraviolet light (UV light) from passing through the Earth’s atmosphere. These wavelengths cause skin cancer, sunburn and cataracts, which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals. These concerns led to the adoption of the Montreal Protocol in 1987, which bans the production of CFCs, halons and other ozone-depleting chemicals.
The ban came into effect in 1989. Ozone levels stabilized by the mid-1990s and began to recover in the 2000s. Recovery is projected to continue over the next century, and the ozone hole is expected to reach pre-1980 levels by around 2075. The Montreal Protocol is considered the most successful international environmental agreement to date.
In April, instruments aboard NASA’s Operation IceBridge airborne campaign and the Ice, Cloud and Land Elevation Satellite-2 succeeded in measuring the same Arctic sea ice at the same time, a tricky feat given the shifting sea ice. Scientists have now analyzed airborne and spaceborne height measurements, and found that the two datasets match almost exactly, demonstrating how precisely ICESat-2 can measure the heights of the sea ice’s bumpy, cracked surface.
Arctic sea ice likely reached its 2019 minimum extent of 1.60 million square miles (4.15 million square kilometers) on Sept. 18, tied for second lowest summertime extent in the satellite record, according to NASA and the National Snow and Ice Data Center.
The Arctic sea ice cap is an expanse of frozen seawater floating on top of the Arctic Ocean and neighboring seas. Every year, it expands and thickens during the fall and winter and grows smaller and thinner during the spring and summer. But in the past decades, increasing temperatures have caused marked decreases in the Arctic sea ice extents in all seasons, with particularly rapid reductions in the minimum end-of-summer ice extent. The shrinking of the Arctic sea ice cover can ultimately affect local ecosystems, global weather patterns, and the circulation of the oceans.
Video Credit: NASA Goddard/Lead Producer: Katie Jepson (USRA); Technical Support: Aaron E. Lepsch (ADNET); Scientists: Nathan T. Kurtz (NASA/GSFC), Walt Meier (NASA/GSFC); Lead Visualizers: Trent L. Schindler (USRA), Cindy Starr (GST); Lead Animator: Bailee DesRocher (USRA); Narrator: LK Ward (USRA); Visualizer: Lori Perkins (NASA/GSFC); Lead Writer: Maria-Jose Vinas Garcia (Telophase); Videographers: Kate Ramsayer (Telophase), Jefferson Beck (USRA), John Caldwell (AIMM)
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