While scientists around the world are confined to their homes during the COVID-19 pandemic, Earth observing satellites continue to orbit and send back images that reveal connections between the pandemic and the environment.
On Aug. 26, 2020, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard NASA’s Terra satellite passed over the River and Carmel fires in Monterey County, California, got a bird’s eye view of the vast fire burn area.
This false-color map shows the burn area as dark blue and gray, in the center of the image. Vegetation is in red, including agricultural crops along the Salinas River (bright red rectangles) surrounding the towns of Soledad and Gonzales; bare areas with no vegetation and rock are shown in tan and brown. The city of Salinas is in the upper left of the image, obscured by thick clouds.
ASTER obtains high-resolution (15-90 square meters, or 161-969 square feet, per pixel) images of the Earth in 14 wavelengths of the electromagnetic spectrum, ranging from visible to thermal infrared light. Data from ASTER — which is managed by Japan Space Systems and NASA’s Jet Propulsion Laboratory in Southern California — are used by scientists to create detailed maps of land surface temperature, how much infrared energy the land emits, how much light the land reflects and its elevation.
On this occasion, ASTER was able to support NASA’s Disaster Program response to the state’s wildfires, providing data products that can be used by resources on the ground to fight the fires and for scientists to better understand their long-term effects. The area covered here is 21.4 by 31 miles (34.4 by 49.9 kilometers).
NASA’s Terra satellite passed over the Gulf of Mexico early on Aug. 25 and found a very small area of convection from post-tropical cyclone Marco, northeast of its center. All watches and warnings have been dropped as the storm continues to weaken toward dissipation.
Visible imagery and surface observations indicated that Marco made landfall around 7 p.m. EDT on Aug. 24 near the mouth of the Mississippi River. The center continued to move west and moved offshore and south of Louisiana by Aug. 25.
NASA’s Terra Satellite Reveals Effects of Wind Shear
NASA’s Terra satellite uses infrared light to analyze the strength of storms by providing temperature information about the system’s clouds. The strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.
On Aug. 25 at 12:30 a.m. EDT (0430 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite observed Marco in infrared light and found a small area of storms where cloud top temperatures as cold as minus 50 degrees Fahrenheit (minus 45.5 Celsius) over the western Florida Panhandle and coastal Alabama. Those storms were being pushed northeast of Marco’s center from southwesterly wind shear. Satellite imagery also shows the low-level circulation center was a swirl of clouds south of Louisiana, over the Gulf of Mexico.
In the Aug. 25, Marco discussion at 5 a.m. EDT, NHC Senior Hurricane Specialist Stacy Stewart noted, “Marco has been devoid of any significant convection for at least 12 hours. [NOAA’s Advanced Scatterometer] ASCAT scatterometer surface wind data around 0239Z (10:39 p.m. EDT on Aug. 24) suggested that Marco might have degenerated in a north-to-south elongated trough (elongated area of low pressure). Based on this information, Marco has been downgraded to post-tropical remnant low [pressure area].”
About Wind Shear
The shape of a tropical cyclone provides forecasters with an idea of its organization and strength. When outside winds batter a storm, it can change the storm’s shape and push much of the associated clouds and rain to one side of it. That is what wind shear does.
In general, wind shear is a measure of how the speed and direction of winds change with altitude. Tropical cyclones are like rotating cylinders of winds. Each level needs to be stacked on top each other vertically in order for the storm to maintain strength or intensify. Wind shear occurs when winds at different levels of the atmosphere push against the rotating cylinder of winds, weakening the rotation by pushing it apart at different levels.
Marco’s Final Status
At 5 a.m. EDT (0900 UTC) on Aug. 25, NOAA’s National Hurricane Center (NHC) reported the center of Post-Tropical Cyclone Marco was located near latitude 28.8 degrees north and longitude 91.2 degrees west. That is about 60 miles (100 km) south of Morgan City, La. and 110 miles (175 km) south-southeast of Lafayette, La. The post-tropical cyclone was moving toward the west near 10 mph (17 kph), and this general motion is expected to continue for the next day or so. Maximum sustained winds were near 30 mph (45 kph) with higher gusts. The estimated minimum central pressure was 1008.
Marco Nears its End
Brisk southwesterly vertical wind shear of 30 knots is forecast to increase to near 35 knots in 24 hours, which should prevent the redevelopment of deep convection near the center. On the forecast track, Marco should continue moving westward just offshore the coast of Louisiana until the system dissipates.
NASA Researches Tropical Cyclones
Hurricanes/tropical cyclones are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.
Scientists have been researching how Arctic glaciers responded to global warming as a result of significant temperature increases at the northern polar region?
A July 14, 2020 ASTER image of the St. Patrick Bay Icecaps, Hazen Plateau, Ellesmere Island, Canada, shows that the icecaps have disappeared. Mapping of the icecaps’ extent using aerial photos, GPS, and ASTER images, from 1959 to present, documents their shrinking and eventual vanishing.
Dr. Mark Sezerre (Director of NSIDC), said: “We’ve long known that as climate change takes hold, the effects would be especially pronounced in the Arctic. They’re the victims of human-caused warming that has occurred three times more rapidly in the Arctic than anywhere else.”Satellite data provide the most important method to monitor cryosphere changes on the Earth.
News agency stories that featured this ASTER story:
Copious clouds of smoke spill off the California coast and travel almost 600 miles in NASA’s Terra satellite image from Aug. 19, 2020. In the year 2020, California has already seen 5,762 incidents affecting 204,481 acres (319 sq. miles). That is more than quadruple the number of acres burned in 2019 per CAL Fire. More than 22,000 residents have now been asked to evacuate ahead of the spreading fires near San Mateo and Santa Cruz. Near Vacaville, 10,000 residents have been asked to evacuate. Fifty structures have been destroyed and 50 more are in danger just in that area. So many fires have started around Sonoma, Lake, Napa and Solano counties that they have been dubbed the LNU Lightning Complex because they all began from lightning strikes from summer storms. California continues to experience a sweltering late summer heat wave that has broken several record highs in recent days. The hot, dry conditions are expected to continue at least into the weekend providing perfect conditions for more wildfire outbreaks. California Gov. Gavin Newsom has declared a state of emergency due to the fires on Tuesday.
NASA’s Earth Observing System Data and Information System (EOSDIS) Worldview application provides the capability to interactively browse over 700 global, full-resolution satellite imagery layers and then download the underlying data. Many of the available imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks “right now.” Actively burning fires, detected by thermal bands, are shown as red points. Image Courtesy: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).
Caption: Lynn Jenner with information from CAL Fire.