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Images, data, and information for the Southern Hemisphere

1994 Antarctic MERRA Temperature

Daily progression

The daily progression through the 1994 ozone hole season of the various temperature statistics, comparing 1994 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

MERRA is a NASA reanalysis for the satellite era using a major new version of the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5). The project focuses on historical analyses of the hydrological cycle in a broad range of weather and climate time scales. It places modern observing systems (such as EOS suite of observations in a climate context. Since these data are from a reanalysis, they are not up-to-date. So, we supplement with the GEOS-5 FP data that are also produced by the GEOS-5 model in near real time. These products are produced by the NASA Global Modeling and Assimilation Office (GMAO).

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