A recent data from NASA and National Oceanic and Atmospheric Administration (NOAA) satellites has revealed that the average area covered by the Antarctic ozone hole in the current year was the second smallest in the last 20 years.
Scientists indicated this change to warmer temperatures in the Antarctic lower stratosphere.
Recently, the ozone hole reached its maximum size on Sept. 22, covering 8.2 million square miles (21.2 million square kilometers), that is approximately the combined area of the United States, Canada and Mexico.
However, the average size of ozone hole in 2012 was 6.9 million square miles (17.9 million square kilometers). Earlier, the ozone hole recorded on Sept. 6, 2000 ozone was the largest on record at 11.5 million square miles (29.9 million square kilometers).
"The ozone hole mainly is caused by chlorine from human-produced chemicals, and these chlorine levels are still sizable in the Antarctic stratosphere," said NASA atmospheric scientist Paul Newman of NASA's Goddard Space Flight Center in Greenbelt, Md.
"Natural fluctuations in weather patterns resulted in warmer stratospheric temperatures this year. These temperatures led to a smaller ozone hole," Newman stated.
The ozone layer acts as a protection of Earth’s atmosphere against ultraviolet radiation, which can cause skin cancer. The ozone hole was first appearance was first noticed in the early 1980s. The Antarctic ozone layer likely will not return to its early 1980s state until about 2065, Newman said.
The lengthy recovery of ozone layer is due to the lengthy life of ozone-depleting substances present in the atmosphere. Overall atmospheric ozone is no longer declining, as concentrations of ozone-depleting substances decrease. The decrease has resulted due to an international agreement regulating the production of certain chemicals.
This year also showed a change in the concentration of ozone over the Antarctic and the least value of total ozone in the ozone hole was the second highest level in two decades.
Total ozone, measured in Dobson units (DU), reached 124 DU on Oct. 1. NOAA ground-based measurements at the South Pole recorded 136 DU on Oct. 5. When the ozone hole is not present, total ozone typically ranges from 240-500 DU.
This is the first year growth of the ozone hole has been observed by an ozone-monitoring instrument on the Suomi National Polar-orbiting Partnership (NPP) satellite.
The instrument, called the Ozone Mapping Profiler Suite (OMPS), is based on previous instruments, such as the Total Ozone Mapping Spectrometer (TOMS) and the Solar Backscatter Ultraviolet instrument (SBUV/2), which have flown on multiple satellites. OMPS continues a satellite record dating back to the early 1970s.
In addition to observing the annual formation and extent of the ozone hole, scientists also hope to understand the ozone destruction in the middle and upper stratosphere through OMPS with its Nadir Profiler. Ozone variations in the lower stratosphere will be measured with its Limb Profiler.
"OMPS Limb looks sideways, and it can measure ozone as a function of height. This OMPS instrument allows us to more closely see the vertical development of Antarctic ozone depletion in the lower stratosphere where the ozone hole occurs," said Pawan K. Bhartia, a NASA atmospheric physicist and OMPS Limb instrument lead.
-With inputs from ANI
|
|
Comments:
