Thursday January 18, 2018
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Increase green cover to mitigate urban heat : NASA

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By NewsGram Staff Writer

Washington:  Providing a solution to the recent problem of rising urban heat, a recently conducted study by NASA explained how increasing the green cover can help cities to a great extent.

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Using multiple satellites’ observations, researchers found that areas in the US covered in part by concrete surfaces had a summer temperature 1.9 degrees Celsius higher than surrounding rural areas.

In winter, the temperature difference was 1.5 degrees Celsius higher in urban areas.

At the human level, a rise of one degrees Celsius can raise energy demands for air conditioning in the summer from five to 20 percent.

“This has nothing to do with greenhouse gas emissions. It is in addition to the greenhouse gas effect. This is the land use component only,” said Lahouari Bounoua, research scientist at NASA’s Goddard Space Flight Centre in Greenbelt, Maryland.

The urban heat island effect occurs primarily during the day when urban impervious surfaces absorb more solar radiation than the surrounding vegetated areas, resulting in a few degrees temperature difference.

The urban area has also lost the trees and vegetation that naturally cool the air.

“Anywhere in the US, small cities generate less heat than mega-cities,” Bounoua said.

The reason is the effect vegetation has on keeping a lid on rising temperatures.

“The amount and type of vegetation plays a big role in how much the urbanisation changes the temperature,” added research scientist and co-author Kurtis Thome.

As a by-product of photosynthesis, leaves release water back into the atmosphere in a process called evapotranspiration, which cools the local surface temperature the same way that sweat evaporating off a person’s skin cools them off.

Trees with broad leaves have more pores to exchange water than trees with needles, and so have more of a cooling effect.

“So even though 0.3 degrees Celcius may seem like a small difference, it still may have impact on energy use,” Bounoua said, especially when urban heat island effects are exacerbated by global temperature rises due to climate change.

Understanding the tradeoffs between urban surfaces and vegetation may help city planners in the future mitigate some of the heating effects, the authors noted in a paper that appeared in the journal Environmental Research Letters.

(With inputs from IANS)

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Scientists spot massive ice deposits on Mars

Recent observations by MRO's ground-penetrating Shallow Radar instrument revealed a buried ice layer that covers more ground than the state of New Mexico.

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Scientists found layers of ice on the surface of Mars. Wikimedia Commons
  • Recently, scientists have found layers of ice on the Martian land.
  • Scientists think this ice might be a useful source of water for future humans.
  • The researchers had researched 8 locations on the surface of Mars.

Scientists have unearthed thick and massive deposits of ice in some regions on Mars.

The images taken by the High-Resolution Imaging Science Experiment (HiRISE) camera aboard NASA’s Mars Reconnaissance Orbiter (MRO) showed the three-dimensional structure of massive ice deposits on Mars.

The ice sheets extend from just below the surface to a depth of 100 meters or more and appear to contain distinct layers.

It extending downward from depths as shallow as 1 to 2 meters below the surface, which could preserve a record of Mars’ past climate, the researchers noted in the journal Science.

This ice which was found can help scientists understand the climate history of Mars. IANS
This ice which was found can help scientists understand the climate history of Mars. IANS

“We expect the vertical structure of Martian ice-rich deposits to preserve a record of ice deposition and past climate,” said Colin M. Dundas, from the US Geological Survey.

“They might even be a useful source of water for future human exploration of the red planet,” Dundas added.

The researchers investigated eight locations on Mars and found thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle.

However, erosion in these regions creates scarps that expose the internal structure of the mantle.

The scarps are actively retreating because of sublimation of the exposed water ice.

The layers of ice can be used as water source by future humans on Mars, VOA
The layers of ice can be used as water source by future humans on Mars, VOA

The ice deposits likely originated as snowfall during Mars’ high-obliquity periods and have now compacted into massive, fractured, and layered ice.

Previous researchers have revealed that the Red Planet harbours subsurface water ice.

Recent observations by MRO’s ground-penetrating Shallow Radar instrument revealed a buried ice layer that covers more ground than the state of New Mexico.

NASA’s Phoenix lander had also dug up some ice near the Martian north pole in 2008, however, it is not clear if that is part of the big sheet. IANS