1998/1999 Arctic TOMS and MERRA Ozone
Daily progression and annual means
The daily progression through the 1998/1999 ozone hole season of the various ozone statistics, comparing 1998/1999 to the climatology of all other years. Also, annual plots of statistics for monthly means. 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. The annual plots show the range of daily values that go into each year's average with gray shading.
polar cap ozone
The total column ozone averaged around the polar cap for latitudes north of 63°N. This is a good measure of the overall ozone content in the polar vortex. Care should be used when evaluating these calculations for late October through late February, as a good portion of the area is in polar night. The missing observations are filled from a model.
The minimum ozone is found from total ozone satellite measurements north of 40°N. No interpolation of missing values is performed. This means that the actual minimum value on a day may be estimated too high, especially in the polar night region.
The maximum ozone is found from total ozone satellite measurements north of 40°N. No interpolation of missing values is performed. This means that the actual maximum value on a day may be estimated too high, especially in the polar night region.
ozone mean latitude bands
The annual- and monthly-mean ozone for eight latitude bands: 90°S–90°N (global), 90–60°S, 60–30°S, 30–10°S, 10°S–10°N, 10–30°N, 30–60°N, 60–90°N. No interpolation of missing values is performed. Since the instruments only measure in sunlight, the actual global values for all months, 90–60°S values during April through September, and the 60–90°N values during during October through March may be biased towards the lower latitudes.
The Arctic winter stratosphere is much more dynamic than the Antarctic winter stratosphere. The position and size of the polar vortex plays a vital role the amount and distribution of total column ozone. Very low temperatures are needed to form polar stratospheric clouds (PSCs). Chlorine gases react on the surface of these PSCs to release chlorine into a form that can easily destroy ozone. There is generally about half the area of PSCs and there is much less loss of ozone in the Arctic than in the Antarctic.
The data starting from November 2004 through June 2016 are from the OMI instrument (KNMI / NASA) onboard the Aura satellite. They are the OMTO3d that have been processed in a manner similar to the TOMS data from earlier years.
The ozone minimum is determined only from data actually contained in the processed satellite data. To calculate the ozone hole area, mass deficit, and polar cap ozone missing areas (bad orbits and polar night) are filled using assimilated ozone data (MERRA for 1979 through June 2016, MERRA-2 for July 2016 through August 2017, and GEOS FP from September 2017 on) produced by the Goddard Earth Observing System Data Assimilation System (GEOS DAS). MERRA and MERRA-2 use a version of the GEOS model with the Gridpoint Statistical Interpolation (GSI) atmospheric analysis developed jointly with NOAA/NCEP/EMC. The GEOS FP system integrates forefront versions of the GEOS atmospheric general circulation model with advanced data assimilation techniques, using a broad range of satellite observations.