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

Abstract

Total ozorl½ n-aeasuren-sents o,.,,.,, , •' • ß ,• .......... spacecraft are compared •ith 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%, res•ctively. Major portion of the bias between the space and •ound measurements is attributed to un•rtainties in the ozone absorption coe•cients used in processing the measurements. Precision of total ozone ret•eved 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 measurementis 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 vacations 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 redu• any further drift. -LAT. 46.8øN _ LONG. 9.7øE --_ ß . ß .,.

Recalibration of the hohenpeissenberg dobson spectrophotometer 104 presuming ?effective absorption coefficients?

“…Simultaneous measurements with the Hohenpeissenberg Dobson 104 confirmed, that it yielded ozone data which are 0-3 % too low depending on the relative optical depth # of the ozone layer. Comparisons with satellite data (Mateer, 1985;Bojkov and Mateer, 1985;AES, 1984;Fleig et al, 1983;Bhartia et al, 1984) and with Brewer 10 showed the same behaviour (mean difference of 2% with diurnal and seasonal variation due to/a). The calibration check with the travelling standard lamp (Grass and Komhyr, 1985;Bojkov and Mateer, 1985)resulted in an estimated error of about -2% (the given error of -6.1% in the Grass/Komhyr paper is wrong, because the Dobson 104 N-correction value was not included in the error calculation).…”

Total ozone amount trend at St Petersburg as deduced from Nimbus-7 TOMS observations

“…Intercomparisons between TOMS observations and data from other instruments have shown that TOMS accuracy and precision are of the order of 2 per cent or better (e.g., Krueger 1983, Bhartia et al 1984). The small drift in the data of approximately -0-4 per cent per year (Fleig et al 1988), is corrected by using an algorithm assuming that this drift is proportional to the wavelength separation (Herman et al 1991, WMO 1988.…”

Total ozone measurements over Athens: intercomparison between Dobson, TOMS (version 6) and SBUV measurements

“…TOMS data quality has been studied by comparison with Dobson-based measurements by several authors (Bhartia et al 1984, Bojkov et al 1988, Fleig et al 1988 ). Most of them used a global network of Dobson stations, or only the world primary standard Dobson spectrophotometer no.…”