It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, June 27, 2020
Winds blow massive Saharan dust cloud into U.S. airspace
Just this past week, the dust floated across the Caribbean into the southern Gulf of Mexico, and now forecasters say it'll move inland over parts of the U.S. Gulf Coast through Saturday. Photo courtesy of NOA
June 27 (UPI) -- Dust from the Sahara Desert that has been pouring off the western coast of Africa and into the Atlantic has effectively put the Atlantic hurricane season on pause, with the exception of short-lived Tropical Storm Dolly, which formed on Tuesday in the North Atlantic.
The dust is largely impacting the Gulf Coast, but could push northward into the airspace above a few other states farther inland.
The robust plume of dust, which satellite imagery showed had reached into U.S. airspace by Friday, has been felt by many across the Caribbean, where it left behind a thin coating on the ground in some areas. The sky turned hazy over the U.S. Virgin Islands, Puerto Rico and Cuba, and visibility was drastically reduced in some areas. By Friday morning, the air quality in Galveston, Texas, where AccuWeather's Bill Waddell is stationed, had plunged from "excellent" on Thursday evening to "unhealthy."
Dusty skies were also observed in Panama City Beach on Friday morning, according to video posted on social media, and dust appeared to be hanging low in the skies over the Houston skyline, a photo posted on social media by Sergio Chapa showed.
"A quick glance out the window, it's easy to confuse it for fog," Chapa, a 44-year-old Houston resident told AccuWeather, adding that the haze looked like fog but with, "a slight brown tint."
"This is much different from ozone action days, but not quite like a forest fire," Chapa said. "I wear glasses and I was wearing a face mask. My eyes are fine, but even with the mask, my throat is irritating after talking around for about 30 minutes in the dust storm."
Dust is often pushed off the African coast during the early stages of Atlantic hurricane season, but the vastness of this episode has raised eyebrows.
The cloud is part of what's known as the Saharan Air Layer, which usually occupies a 2- to- 2.5-mile-thick layer of the atmosphere, with a base starting about 1 mile above the surface, according to the National Oceanic and Atmospheric Administration.
AccuWeather meteorologists have been tracking dust emerging from the Africa coast since April, but there has been an uptick in activity since around June 14. Dust is most commonly observed over the Atlantic into July before it becomes less of an issue later in the hurricane season. AccuWeather's top hurricane expert Dan Kottlowski said the African Easterly Jet has been stronger than normal and this has produced more dust.
"Certainly the dust episodes in the Caribbean have been more robust than normal due to the active jet," Kottlowski said.
Just this past week, the dust floated across the Caribbean into the southern Gulf of Mexico, and now forecasters say it'll move inland over parts of the U.S. Gulf Coast through Saturday.
On June 23, @NOAA's #GOESEast viewed the #SaharanAirLayer (or #SAL) over Cuba, while a storm erupted through its dusty haze. During this time of year, the SAL often blows westward from Africa's Saharan Desert and can travel thousands of miles away.
The dust is forecast to be primarily concentrated over Gulf Coast states, but some could expand farther north into Oklahoma, Arkansas and eastward into Tennessee, Kottlowski said. He added that the forecast does not call for high concentrations of dust to play a role in the overall weather pattern across the northeastern U.S. Some dust could "barely" reach into Tennessee and southern Virginia, Kottlowski said.
"Dust, like any pollutant, can find its way farther north over time and it's possible some dust could work into the Great Lakes next week but it probably would not be very noticeable. A storm system forming over Quebec this weekend will move southeast into Maine early next week and bring a wind flow out of Canada and not up from the tropics," Kottlowski said.
Dust particles can produce vibrant sunsets and sunrises, but if there is too much of an accumulation, then those sunsets or sunrises can turn out dull. Dust is usually most noticeable when the skies are cloud-free, according to Kottlowski. The cloud cover combined with the haziness from dust obscured the sunrise in Galveston on Friday morning, Waddell reported.
Air quality levels could also drop from moderate to unhealthy over southern and eastern Texas, according to Plume Labs. Those with respiratory issues are being urged to limit the amount of time they spend outdoors. AccuWeather and Plume Labs have a partnership that allows users to monitor the realtime air quality in a given location from the AccuWeather website or mobile app.
Kottlowski said there is a second large area of dust over the open Atlantic, but it seems less impressive than the first batch of dust currently invading the U.S. The second round of dust is likely to dissipate faster, thanks in part due to stronger winds forcing it westward. However, it will still bring a "considerable" amount of dust to the Gulf of Mexico early next week which will result in hazy conditions and milky-looking skies.
Longer range forecasts show an easing in the amount of dust entering the atmosphere over the next week as the African Easterly Jet, which is responsible for triggering the potent storms that kick up the dust, is forecast to relax a bit, according to Kottlowski.
NASA-NOAA's Suomi NPP satellite analyzes Saharan dust aerosol blanket
NASA/GODDARD SPACE FLIGHT CENTER
IMAGE: THIS JUNE 24, 2020 IMAGE IS FROM THE SUOMI NPP OMPS AEROSOL INDEX. THE DUST PLUME MOVED OVER THE YUCATAN PENINSULA AND UP THROUGH THE GULF OF MEXICO. THE LARGEST... view more
CREDIT: CREDITS: NASA/NOAA, COLIN SEFTOR
Dust storms from Africa's Saharan Desert traveling across the Atlantic Ocean are nothing new, but the current dust storm has been quite expansive and NASA satellites have provided a look at the massive June plume. NASA-NOAA's Suomi NPP satellite showed the blanket of dust had moved over the Gulf of Mexico and extended into Central America and over part of the eastern Pacific Ocean.
NASA uses satellites and other resources to track aerosol particles made of desert dust, smoke, and volcanic ash. The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image while the Ozone Mapping and Profiling Suite (OMPS) Nadir-Mapper (NM) instrument aboard the Suomi-NPP satellite provided absorbing aerosol index values. The OMPS index indicates the presence of light absorbing aerosol particles (ultraviolet (UV)-absorbing particles in the air) such as desert dust. The absorbing aerosol index is related to both the thickness and height of the aerosol layer.
The Absorbing Aerosol Index is useful for identifying and tracking the long-range transport of volcanic ash from volcanic eruptions, smoke from wildfires or biomass burning events and dust from desert dust storms. These aerosol particals can even be tracked over clouds and areas covered by snow and ice.
Colin Seftor, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., created imagery from the Suomi NPP OMPS absorbing aerosol index and visible imagery from the VIIRS instrument He said that on June 23 and 24 the dust plume had moved completely over Mexico's Yucatan Peninsula, up through the Gulf of Mexico and into southern Texas. "At that point, the situation becomes more complicated because the absorbing aerosol index signal seen further north into Texas, Oklahoma, Nebraska, etc., is probably a mix of dust and smoke from the numerous fires burning in the southwest U.S. You can also see that the dust traveled over Central America and out into the Eastern Pacific Ocean."
On June 25, an animation that combined OMPS aerosol index and VIIRS visible imagery from NASA/NOAA's Suomi NPP satellite was created at NASA Goddard showing the movement the Saharan dust cloud from June 15 to 25, 2020,. The animation showed the dust plume streamed from Africa's west coast over the Atlantic into the Caribbean Sea and up through the Gulf of Mexico over some of the Gulf states.
Aerosol particles absorb and scatter incoming sunlight, which reduces visibility and increases the optical depth. Aerosol particles have an effect on human health, weather and the climate. Aerosol particles are produced from many events including human activities such as pollution from factories and natural processes such as smoke from fires, dust from dust storms, sea salt from breaking waves, and volcanic ash from volcanoes. Aerosol particles compromise human health when inhaled by people with asthma or other respiratory illnesses. Aerosol particles also affect weather and climate by cooling or warming the earth as well as enhancing or preventing cloud formation.
On June 18, NASA's Earth Observatory noted the thickest parts of the plume appeared to stretch about 2,500 kilometers (1,500 miles) across the Atlantic Ocean. By June 24, the plume extended over 5,000 miles.
Dust from Africa can affect air quality as far away as North and South America if it is mixed down to ground level. But dust can also play an important ecological role, such as, fertilizing soils in the Amazon and building beaches in the Caribbean. The dry, warm, and windy conditions associated with Saharan Air Layer outbreaks from Africa can also suppress the formation and intensification of tropical cyclones.
"While Saharan dust transport across the ocean to the Americas is not uncommon, the size and strength of this particular event is quite unusual," Seftor said. "Also, if you look off the coast of Africa you can see yet another large cloud coming off the continent, continuing to feed the long chain of dust traveling across the Atlantic."
No comments:
Post a Comment