Total Ozone Data Sets Research Articles

An attempt to reconstruct UV radiation data from total ozone and auxiliary datasets

This paper attempts to reconstruct UV radiation data by means of a radiative transfer model that uses as inputs the total ozone data (ground and satellite data) and other auxiliary datasets. A comparison with existing UV data showed a satisfactory agreement between the compared series. In the absence of continuous UV monitoring, this method is the only one available for climatological purposes.

Dynamical containment of Antarctic ozone depletion

Over the past two decades both the severity of Antarctic ozone depletion and the size of the Antarctic ozone hole have increased. A satellite‐based, assimilated total column ozone data set and NCEP/NCAR meteorological fields from 1979 to 2000 have been used to examine the long‐term evolution of the ozone hole and its dependence on the size of the dynamical vortex and the size of the region of low temperatures. Equivalent latitude zonal means of these data have been calculated to show more directly the expansion of the Antarctic ozone hole and its encroachment on the vortex edge. While the size of the dynamical vortex and the vortex region with temperatures below 195 K (where polar stratospheric clouds are expected to form) has changed little, the area with ozone below 220 DU (the contour defining the ozone hole) has steadily increased. Over the 20 year period, the severity of the ozone depletion within the core of the vortex has increased. This, combined with the nature of the mixing regimes within the polar vortex may explain the increase in the area of the ozone hole.

Total ozone determinations from National Oceanic and Atmospheric Administration operational solar backscattered ultraviolet 2 instrument observations: An update

Total ozone amounts have been derived from observations of the Solar Backscattered Ultraviolet 2 (SBUV/2) instruments on National Oceanic and Atmospheric Administration (NOAA) operational satellites since 1985. The data from the NOAA‐9 instrument for the period 1985–1997 have been reprocessed using instrument characterizations based on in‐orbit operation and comparisons with Shuttle Solar Backscattered Ultraviolet (SSBUV) observations. The data from the NOAA‐11 satellite for the period 1989–1994 have also been reprocessed using mainly internal spacecraft information. The data from the NOAA‐14 satellite for the period 1995–1998 have been reprocessed using complete instrument characterization. The NOAA‐11 and NOAA‐14 data for 1998 to the present, briefly discussed herein, are preliminary. The calibration adjustments used in the reprocessing of NOAA‐9, NOAA‐11, and NOAA‐14 total ozone data are internal, with the exception of those derived from SSBUV analysis, and are independent of Dobson and Total Ozone Mapping Spectrometer (TOMS) total ozone measurements. The reprocessed data have been validated with ground‐based Dobson spectrophotometer observations, and are compared to other sources of total column ozone amounts. The mean bias between NOAA‐9 data and Dobson data is 1.9%±0.6% over the 12‐year record with a trend of 0.1% per year. The mean bias between NOAA‐11 and Dobson data is 0.8%±0.2% with a near‐zero trend. The mean bias between NOAA‐14 and Dobson data is 1.5%±0.3% with a trend of 0.2% per year; the NOAA‐14 calibration and characterization data for the period 1998 to the present are not yet fully analyzed. The methods used in the validations are discussed here, as are some reasons for the results. Finally, a recommendation is made for the use of a relatively continuous total ozone data set.

Global structure of ozone response to solar and galactic cosmic ray influence (ground based and satellite data analysis)

A joint statistical analysis of solar proton fluxes measured by Russian polar satellites system “Meteor”, total ozone data sets for different points of ground based observations, and galactic cosmic ray fluxes (balloon long-term measurements in Russia) were used to study the magnitude and spatial structure of total ozone response (ground based and TOMS data).Yearly averaged values only were used for analysis to estimate the long-term effects in ozone response. The results of the study has revealed the negative ozone response to solar protons at high latitudes for the years of strong SPE's , which decreased to the low latitudes with zero effect at 45° N. Similar regression procedure for the lower latitudes has revealed a positive response of total ozone to the proton's forcing. Galactic cosmic rays produced a decadal cycle in total ozone with amplitude of about several DU at high latitudes with opposite phase to solar cycle. The response of total ozone to GCR influence has a negative trend of about 0.7 DU per decade at 43° N and increases to higher latitudes.

Air depression over south pole during Antarctic spring and its possible influence on ozone content in this region

Air depression during Antarctic spring, its long-term behaviour and connection with ozone content has been investigated on base of rocket data for polar regions and total ozone data sets for South pole (TOMS data) for 1979–1990. It was shown, that air pressure depression near South polar region in September in the lower stratosphere has a visible (about 5% per decade) negative trend similar to the tendency which total ozone records reveal. Rather high correlation (+0.82) between air pressure in the stratosphere and total ozone content for spring in Antarctica was found.

Approximate separation of volcanic and 11‐year signals in the SBUV‐SBUV/2 total ozone record over the 1979‐1995 Period

The combined Nimbus 7 SBUV, NOAA 11, and preliminary NOAA 9 SBUV/2 monthly zonal mean total ozone data set, extending from January 1979 to December 1995, is analyzed with a multiple regression statistical model that includes a term to describe the direct effect of volcanic aerosols on total ozone. Outside of polar regions, which are not included in this analysis, the volcanic regression coefficients in the northern hemisphere are negative (consistent with heterogeneous chemical losses of ozone on volcanic sulfate aerosols) and reach their maximum values between 40°N–60°N latitude. Although inclusion of the aerosol term in the statistical model introduces some additional uncertainty to the derived solar response, statistically significant values of the solar coefficients are found in northern and southern subtropical regions throughout the year, with maximum amplitudes of ∼2.5% at 30° latitude in both hemispheres during winter. We conclude that the 11‐year signal in the SBUV‐SBUV/2 total ozone record is approximately separable from volcanic aerosol effects.

Intercomparison of total ozone data measured with Dobson and Brewer ozone spectrophotometers at Uccle (Belgium) from January 1984 to March 1991, including zenith sky observations

More than 7 years of quasi‐simultaneous observations of the total ozone amount measured with Dobson spectrophotometer 40 and Brewer spectrophotometer 16, both located in Uccle (50°48′N, 4°21′E), are compared. Direct Sun observations with both instruments show a significant drift relative to each other of 0.1% per year. On the other hand, the Brewer instrument measurements indicate that the SO2 amount at Uccle has had a strong downward trend of 8.9% per year over the same time period. This is confirmed by in situ measurements of SO2 density near the ground. If the SO2 trend is taken into account in the comparison between Brewer and Dobson instrument total ozone values, the two total ozone data sets show no drift with respect to each other. The question of SO2 tendency therefore deserves investigation in any trend analysis of Dobson instrument total ozone data. Quasi‐simultaneous zenith sky observations made with both instruments are also intercompared. Results indicate that the coherence between direct Sun and zenith sky data of the Brewer instrument is slightly better than that of the Dobson instrument.

Intercomparison of the NIMBUS 7 SBUV/TOMS total ozone data sets with Dobson and M83 results

Total ozone measurements made by the SBUV and TOMS instruments on the NIMBUS 7 spacecraft are compared with measurements from 62 Dobson and 18 M83 stations. On the average, TOMS ozone values are 6.6% smaller than Dobson and 9.1% smaller than M83; corresponding SBUV biases are 8.3% and 11.3%, respectively. Use of SBUV or TOMS as a transfer standard reveals an apparent bias between the Dobson and M83 networks of 3.0 or 2.5%respectively. Major portion of the bias between the space and ground measurements is attributed to uncertainties in the ozone absorption coefficients used in processing the measurements. Precision of total ozone retrieved from either the SBUV or the TOMS instrument is shown to be better than 2%, which is comparable to that of a well run Dobson station. Precision of a typical Dobson measurement is estimated at about 2% and that of an M83 measurement is estimated to be 4%. Apparent station to station biases of up to 11.2% for Dobson and 15.5% for M83 are shown. Daily and seasonal variations of ozone measured by the satellite over selected Dobson stations are found to be in excellent agreement with the ground observations. An instrumental drift is found in the SBUV/TOMS total ozone measurements that is essentially linear with time and has a rate of 0.5% per year for the first year of data. A better understanding of instrument changes is expected to help reduce any further drift.