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Images, data, and information for the Southern Hemisphere

2013 Antarctic MERRA2 Temperature

Daily progression

The daily progression through the 2013 ozone hole season of the various temperature statistics, comparing 2013 to the climatology of all other years. Clicking a link will bring up, in a new window, a PDF vector plot or a plain-text ASCII data file that is suitable for input into any program.

minumum temperature

The minimum Antarctic temperature is determined for latitudes south of 50°S. (Image is shown for 1 April–31 December on the 50-hPa surface.)

60°–90°S Temperature

The temperature averaged around the polar cap for latitudes south of 60°S. This is a good measure of the overall temperature in the polar vortex. (Image is shown for 1 April–31 December on the 50-hPa surface.)

55°–75°S Temperature

The temperature averaged for 55°S to 75°S. This is a good measure of the temperature in the polar vortex boundary region. (Image is shown for 1 April–31 December on the 50-hPa surface.)

PSC NAT area

Area of PSCs formed from nitric acid trihydrate (NAT). We assume a fixed profile of nitric acid, with a value of 4.54 ppt on the 460 K potential temperature surface, and a fixed concentration of water at 5.0 ppm. We interpolate temperatures to potential temperature surfaces and then find the area of temperatures less than the condensation temperature for each surface. (Image is shown for 1 April–31 December on the 460-K surface.)

PSC NAT volume

To calculate the volume, we first calculate areas and then integrate the areas over the range of input levels. Instead of using fixed theta levels, we calculate an average value of theta over each pressure level from 60°S to 90°S. (Image is shown for 1 April–31 December.)

PSC ice area

Area of PSCs formed from ice. We assume a fixed profile of nitric acid, with a value of 4.54 ppt on the 460 K potential temperature surface, and a fixed concentration of water at 5.0 ppm. We interpolate temperatures to potential temperature surfaces and then find the area of temperatures less than the condensation temperature for each surface. (Image is shown for 1 April–31 December on the 460-K surface.)

PSC ice volume

To calculate the volume, we first calculate areas and then integrate the areas over the range of input levels. Instead of using fixed theta levels, we calculate an average value of theta over each pressure level from 60°S to 90°S. (Image is shown for 1 April–31 December.)

Data description

The depth and area of the Antarctic ozone hole are governed by the temperature of the stratosphere and the amount of sunlight reaching the south polar region. Temperatures that are cold enough can form polar stratospheric clouds (PSCs). PSCs are an important component in the destruction of ozone molecules. PSCs can be formed when temperatures fall below a given threshold for each type of PSC. The formation temperature is dependent on concentrations of nitric acid and water vapor, and the potential temperature of the air. PSCs can be formed from sulfate aerosols, nitric acid trihydrate (NAT), or ice.

Data source

The data are from the Modern-Era Retrospective analysis for Research and Applications, Version 2 ( MERRA-2) assimilation, produced by the Goddard Earth Observing System Data Assimilation System (GEOS DAS). MERRA-2 uses a version of the GEOS model with the Gridpoint Statistical Interpolation (GSI) atmospheric analysis developed jointly with NOAA/NCEP/EMC. Since it takes about two months to incorporate these data into the statistics, we supplement the MERRA-2 assimilation with the GEOS FP assimilation system that provides analyses and forecasts. This assimilation system is also produced by the GEOS DAS. and integrates forefront versions of the GEOS atmospheric general circulation model with advanced data assimilation techniques, using a broad range of satellite observations.

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