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Heat flux distribution of Antarctica unveiled

first_imgAntarctica is the largest reservoir of ice on Earth. Understanding its ice sheet dynamics is crucial to unraveling past global climate change and making robust climatic and sea level predictions. Of the basic parameters that shape and control ice flow, the most poorly known is geothermal heat flux. Direct observations of heat flux are difficult to obtain in Antarctica, and until now continent-wide heat flux maps have only been derived from low-resolution satellite magnetic and seismological data. We present a high resolution heat flux map and associated uncertainty derived from spectral analysis of the most advanced continental compilation of airborne magnetic data. Small-scale spatial variability and features consistent with known geology are better reproduced than in previous models, between 36% and 50%. Our high-resolution heat-flux map and its uncertainty distribution provide an important new boundary condition to be used in studies on future subglacial hydrology, ice-sheet dynamics and sea-level changelast_img read more

Armyworms marching

first_imgBy Mike IsbellUniversity of GeorgiaLook at it this way: all those little brown dots that cover the ground after armyworms have finished eating your yards and fields are worm dung — natural fertilizer. And you’re getting it for free.Of course, you no longer have a yard or field. That’s how bad armyworms can be.”From a distance, my pasture looks like it’s trying to walk off,” said a caller to my county extension office. He knew what the problem was.These green or brown worms can eat up pastures, hay fields and yards faster than my cousins grabbed up all the deviled eggs at my mother’s family reunion. They can literally turn acres of fields, pastures or lawns into nothing more than stubs sticking out of the ground. (That’s the worms, not my cousins.)On the way out to the caller’s field, we met his son, who handed me a quart jar with some of the caterpillars in it. It didn’t take me but a second to tell John, “Yep, you’ve got armyworms.”What a few days ago was 45 acres of Bermuda grass pasture was now stubs. And you could see the armyworms by the thousands dropping off the stubs onto the ground.After armyworms finish one field, they keep marching on to other fields. One farmer told me the worms ate all the grass in one field and then crossed the highway on their way to another. “There’s a big greasy spot stretching across the highway where thousands of worms have been run over by cars,” he said.The problem, which crops up every now and then, starts with thousands of nondescript, brownish moths. The females lay clusters of eggs on grasses and other food plants. The eggs hatch in two to five days.The caterpillars feed for about 12 days and then pupate. Adult moths emerge seven to 14 days later and are active mainly at night. The entire life cycle is about a month.The caterpillars are about an inch and a half long when full-grown. They vary from green or tan to nearly black and usually have an inverted white “Y” on their face.Don’t expect the armyworms to go away with cool weather. Cooler weather just increases the time the insect stays in the caterpillar stage. And the longer it stays in the caterpillar stage, the more it eats.Quick action is required to control these pests. Spray hayfields and pastures when caterpillar counts reach three per square foot.You can use Sevin, but some worms are resistant to Sevin, so test a small area before you spray the whole field. Otherwise, you may be wasting your time and money. If worms are dead after 24 hours in the test area, then spray the whole field.Homeowners can use several insecticides, including Sevin.Don’t wait. Armyworms can eat your pastures and lawns to nothing and then move on to something else to eat.And just to be on the safe side, don’t stand still too long. And don’t wear green.last_img read more