Descriptions of Stratospheric Ozone Products
Polar Vortex Area
Air parcels move on isentropic surfaces (surfaces of equal potential temperature) rather than pressure surfaces. The 450K surface in the south polar area lies between the 70 mb and 50 mb pressure surfaces. This is near the altitude where ozone is in greatest abundance in the vertical profile. This figure shows the size of the polar vortex with respect to previous years. The polar vortex defines the area in which cold polar air is trapped by the very strong winds of the Polar Night Jet.
During the winter/spring period, when the polar vortex is strongest, air outside of the vortex can not enter. So, because the warm air from the mid latitudes cannot mix with the cold polar air, the polar air continues to get colder due to radiative loss of heat. Also, when ozone in the vortex is depleted, it is not replenished with ozone rich air from outside the vortex. Not until mid to late Spring does the polar vortex weaken and eventually break down. After this, thorough mixing occurs and ozone amounts are replenished.
Size of the Ozone Hole
Every year for the past several decades the return of sunlight to the high latitudes of the Southern Hemisphere has produced massive depletion of ozone over Antarctica.
Observations in Antarctica initiated in the 1950's document this progressive loss of ozone during the Southern Hemisphere spring. Satellite data showed that the affected area was not just limited to over the observation stations, but over most of Antarctica. This area of 50-75% depletion of total ozone has been labeled as the "ozone hole". The ozone hole is defined geographically as the area wherein the total ozone amount is less than 220 Dobson Units. The ozone hole has steadily grown in size(up to 27 million sq. km.) and length of existence(from August through early December) over the past two decades.
SBUV/2 Northern Hemisphere Total Ozone
This map shows the most recent analysis of the Northern Hemsisphere total ozone from the Solar Backscattering UltraViolet (SBUV/2) instrument on board the NOAA polar orbiting satellite.
The SBUV/2 instrument cannot make observations in the polar night region because it relies upon backscattered sunlight. The blackened area centered over the pole represents the latitudes in which no observations can be made.
SBUV/2 Southern Hemisphere Total Ozone
This map shows the most recent analysis of the Southern Hemsisphere total ozone from the Solar Backscattering UltraViolet (SBUV/2) instrument on board the NOAA polar orbiting satellite. In austral spring the analysis shows the "ozone hole" (values below 220 Dobson Units) over Antarctica and the Antarctic Ocean. This area of low ozone is confined by the polar vortex. Usually circular in August and September, the vortex tends to elongate in October, stretching towards inhabited areas of South America. By November, the polar vortex begins to weaken and ozone rich air begins to mix with the air in the "ozone hole" region. The "ozone hole" is usually gone by late November/early December.
The SBUV/2 instrument can not make observations in the polar night region because it relies upon backscattered sunlight. The blackened area centered over the pole represents the latitudes in which no observations can be made.
Stratosphere Monitoring Ozone Blended Analysis (SMOBA)
These are hemispheric images of total ozone as generated by the SMOBA technique. Since the SBUV/2 cannot measure backscattered ultraviolet radiation during the polar night, a method was developed by the Climate Prediction Center to combine ozone data from the SBUV/2 and the TOVS to produce a blended ozone product.
Global Temperature Time Series
The CPC global temperature analyses are satellite-derived stratospheric temperature plots at 50 hPa (approximately 20 km), 10 hPa (approximately 30 km) and 2 hPa (approximately 42 km). These temperatures are averaged according to different latitude bands (90-60N, 65-25 N, 25N-25S, 25-65S, 65-90S, Northern Hemisphere and Southern Hemisphere). A hemispheric average and values at the poles are also presented. The red line represents actual values for the current year, while the green line represents the long-term average since 1979. Extreme maximum and minimum temperatures are denoted by the black lines (solid and dashed).
TIROS Operational Vertical Sounder (TOVS)
These images present hemispheric daily values of total ozone as presented by the TOVS High Resolution Infrared Vertical Sounder (HIRS) aboard the NOAA Polar Orbiting Satellites.
Area with Temperatures less than -78C
This figure shows the area within the polar vortex that has temperatures low enough to form Polar Stratospheric Clouds (PSCs). The ice crystals that make up these PSCs are where heterogeneous photo-chemical destruction of ozone take place. So as the area of low temperatures becomes larger, there is greater likelihood of PSCs forming. When this area becomes sunlit, enhanced ozone destruction takes place.
South Pole Total Column Ozone
The Earth System Research Laboratory presents 3 maps depicting time-series measurements from ozonesondes released at the South Pole. South Pole total column ozone and ozone measured in the 12-20 kilometer column are produced, along with temperatures observed in the 20-24 kilometer layer. In addition to total ozone, columnar ozone between the altitudes of 12 and 20 kilometers is useful since Antarctic ozone depletion occurs primarily at these levels.
Daily Total Column Ozone from Dobson Spectrophotometer
The Earth System Research Laboratory provides total ozone data from a network of Dobson Spectrophotometer sites from around the world. Land-based measurements of total ozone are available in near real-time for the Boulder, Colorado location, with archived data for the entire network of sites available for download. The data period of record begins in the early 1960s for some stations. This plot for Boulder, Colorado is updated daily at the end of each day when conditions permit an observation. These are preliminary data. Finalized data for Boulder and other sites in the NOAA/ESRL Cooperative Dobson Network are available approximately six months after they are obtained.
Satellite Derived Stratospheric Temperatures
The Microwave Sounder Unit (MSU) aboard NOAA's TIROS-N series of polar orbiting satellites has measured temperatures in the stratosphere and troposphere since 1979. Lower-stratospheric temperatures are measured from MSU channel 4, which has a peak in its weighting function from 70-100 millibars (approximately 9-12 km above the earth). These data are adjusted for time-dependent biases by NASA and the Global Hydrology and Climate Center at the University of Alabama in Huntsville before time series of stratospheric temperatures are produced at the National Climatic Data Center. Monthly temperature time series of lower stratospheric temperatures are available for the Arctic (90N-60N), Antarctic (60S-90S) and the middle latitudes and tropics (60N-60S).
Stratospheric Analyses and Forecasts
The Climate Prediction Center produces maps of stratospheric temperature at pressure levels from 1 to 70hPa (mb). The analyses are produced twice-daily from the Advanced Microwave Sounding Unit aboard the NOAA polar orbiting satellites. Additionally, forecasts of temperatures between 10 and 100hPa (mb) as well as total ozone are produced from the National Centers for Environmental Prediction (NCEP) Medium Range Forecast (MRF) model. These forecast products are available out to 5 days in 24-hour time steps, based on a model initialization time of 0000 UTC. These maps show the location of the very cold polar air that will support the formation of Polar Stratospheric Clouds and the photo-chemical destruction of ozone.