Guest Essay by Kip Hansen
Weather radar is a wonderful thing — and many of us depend on it to know such important facts such as “When will that rainstorm hit my area?”.
At sea, I used my on-board radar to detect the edges of rainfall and rain squalls, track them, and predict when and if they would affect our little sailboat. Occasionally, I used the radar to “see” through rainfall and detect the navigation buoys (which had special radar reflectors mounted on them) that marked the entrance to a safe harbor (the sailing equivalent to “flying on instruments”.)
Some of the online (and broadcast media outlets) use “future radar” to predict the movement of storms — computerized projections mapped on the radar graphic as if it were actual radar return.
“Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather.” — Wiki
But pulse-Doppler radar doesn’t just detect raindrops…. Generally, pulse-Doppler returns reflections from moving particles (rain drops, dense clouds on the move, falling snow or hail, etc) “However, not all non-meteorological targets remain still (birds, insects, dust).”
The featured image for this essay (at the beginning) is a weather radar image from the area north of San Diego, California (between Lancaster and Palm Springs) on the evening of the 4th of June. From an NPR report quoted in Science Alert:
“It was very strange because it was a relatively clear day and we weren’t really expecting any rain or thunderstorms,” meteorologist Casey Oswant of the National Weather Service in San Diego told NPR.
“But on our radar, we were seeing something that indicated there was something out there.”
The answer? Ladybugs. Not dense like a cloud but was observed as “little specks flying by”. The LA Times reported: “… the ladybug bloom appears to be about 80 miles by 80 miles, but the ladybugs aren’t in a concentrated mass that size. Rather, they’re spread throughout the sky, flying at between 5,000 and 9,000 feet, with the most concentrated mass about 10 miles wide.”
That’s a lot of ladybugs!
Like many things in science, there is controversy about what caused the radar image. Some
etymologist entomologists are quoted saying that it was not yet warm enough for such a swarm and another [of course] was worried that it might be an effect of climate change.
NBC News has a 30-second short video on weird things seen on weather radar.
In July of 2015, weather radar reported a vast swarm of grasshoppers and beetles in Texas near Copper Breaks State Park in Quanah, Texas:
CNN reported: “We didn’t have any clouds yesterday to form anything like that,” said Jonathan Kurtz, a meteorologist at the Norman Forecast Office. “Our first indication was some kind of biological feature.”
“What the radar was picking up was bugs, lots and lots of them. Grasshoppers and beetles were flying between the ground and 2,500 feet, covering an area of about 50 miles.”
This is not just a fun and interesting unintended side-benefit of weather radar:
”USDA scientists in College Station, TX, have shown that signals routinely collected by the National Weather Service’s (NWS) Doppler radar network could serve as an early-warning system to track corn earworms and other nighttime traveling pests.
Agricultural Research Service (ARS) meteorologists John Westbrook and Ritchie Eyster at the Southern Plains Agricultural Research Center in College Station focused on the capabilities of what is known as Next Generation Weather Radar, or NEXRAD.
The results showed that NEXRAD was not only capable of tracking insect migration patterns, but it was also superior to the older scanning X-band system in offering a much larger detection range and an ability to determine the direction and speed of insect migration flights without need of weather balloons. Results were published in the International Journal of Biometeorology in April 2013.” Source: USDA
Some examples are shocking:
And this is not a phenomenon restricted to the United States. Over the water in the United Kingdom, a Science Magazine article in 2016, “Radar spots trillions of unseen insects migrating above us” , relates:
“Birds and human vacationers aren’t the only creatures that take to the skies each year to migrate north or south. An analysis of a decade’s worth of data from radars specifically designed to track airborne insects has revealed unseen hordes crossing parts of the southern United Kingdom—2 trillion to 5 trillion insects each year, amounting to several thousand tons of biomass, that may travel up to hundreds of kilometers a day.
The numbers, reported in this week’s issue of Science, are “stunning,” says Silke Bauer, an ecologist at the Swiss Ornithological Institute in Sempach. “Wow,” adds Larry Stevens, an evolutionary ecologist at the Museum of Northern Arizona in Flagstaff. “Can you image what these numbers look like in tropical settings, say, over the basins of the Amazon or the Congo?”
Although some insect migrations are well known (think monarchs), the new work takes a systematic approach to flying insects and hints that such mass movements are surprisingly common. These airborne invertebrates, their bodies packed full of nitrogen and phosphorus, could move significant amounts of key nutrients across the globe. “Insects are little creatures, but collectively they can have a big impact; comparable in magnitude to large ocean migrations [of plankton],” says Lael Parrott, an environmental geographer at the University of British Columbia in Kelowna, Canada.”
One of the insects that migrates to and from the United Kingdom is the highly beneficial insect — the hoverfly.
One paper, whose title tells it all, is “Mass Seasonal Migrations of Hoverflies Provide Extensive Pollination and Crop Protection Services”.
A report in Science Magazine informs us:
“Each year, hundreds of millions of hoverflies cross the English Channel from continental Europe, according to a new radar-based study. Most migratory insects around the world are pests, such as locusts, but luckily for U.K. farmers, the hoverflies are friends.
“The potential benefit is quite large,” says Ben Woodcock, an entomologist with the Centre for Ecology & Hydrology, in Wallingford, U.K., who was not involved in the study. Many hoverfly species pollinate crops, he notes, and their larvae consume aphids, which are pests of wheat and other crops.
Most insect migrations are invisible to the naked eye. But researchers can track and identify them with narrow radar beams. In 2016, a group using the technology and led by ecologist Jason Chapman at the University of Exeter in the United Kingdom reported that trillions of insects migrate in and out of the country each year.”
Seeing insects on your weather radar screen ? “Its Not a Bug, It’s a feature!”
The folks at weather.com give us a neat little video primer on how and why insect movements appear on weather radar. Not just insects, of course, but birds, and bats and dust and trains and ski lifts.
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Author’s Comment Policy:
Hope you enjoyed reading about bugs and weather radar — a light-hearted look at something that was once a problem and is now a specialized tool for tracking mass insect movements that might provide advanced warning of potential damaging insect swarms.
Have a good weekend,
and Thanks for Reading.
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