Ground‐based total ozone column measurements and their diurnal variability

Abstract

[1] Three Brewer spectrophotometers were set up in three tropical sites of South America (in the Bolivian Altiplano and seashore and biomass burning areas of Brazil) to measure the total ozone column (TOC). Only TOC measurements with uncertainties ≤1% (1σ) were considered. Typically, the standard deviation for the diurnal sets of measurements was predominantly ≤1% for two of these sites. The average variability in TOC ranged from 6.3 Dobson units (DU) to 16.8 DU, and the largest variability reached 54.3 DU. Comparisons between ground-based and satellite (Total Ozone Mapping Spectrometer (TOMS)) data showed good agreement with coefficients of determination ≤0.83. However, the quality of the ground-based measurements was affected by the weather condition, especially for one of the sites. Visual observation of the sky from the ground during the measurements with one of the Brewers added to the satellite data of reflectivity and aerosol index supports that statement.Citation: Silva, A. A. (2013), Ground-based total ozone column measurements and their diurnal variability, J. Geophys.

Daily Maximum Erythemal Dose Rates in the Tropics

“…Silva et al . have shown that TOC measurements obtained within a few minutes in Belo Horizonte by a MII have standard deviations up to 4% of the average TOC, and Silva has shown that TOC measurements obtained in Campo Grande (20.44°S, 54.65°W, 532 m a.s.l., 8093 km 2 , Brazil) by a Brewer spectrophotometer can present an average variability of 3% of the daily average TOC. It means the uncertainty in EDR cf caused by the uncertainty of using just one value of TOC per day is practically equal to the correction provided by SRF cf to EDR at SZA < 60° .…”

“…Since there was neither satellite data nor ground‐based measurement of TOC on DEC292009, the monthly average MII TOC for December 2009 ± 1 standard deviation was adopted as the value of TOC for the day. Despite the diurnal variability of 3–4% in TOC , let's assume that each value of TOC in Table is valid at the EDR max times. Then use Figure to determine the corresponding SRF cf for each EDR max .…”

A Semiempirical Approach to the Determination of Daily Erythemal Doses

“…The average values for the satellite parameters of Dist, TOC and R PC under the restriction of Dist ≤ 10.3 km were 6 AE 2 km (1r), 255 AE 11 Dobson Units (DU), and 27 AE 22%, respectively. These are typical values of TOC and R PC for the site (7,23,24).…”

Investigation of atmospheric ozone with remote sensing spectroscopy

“…An opposite diurnal cycle, with a peak shortly after local noon and a gradual decrease thereafter was reported by Kumar et al (2011). Silva (2013), have found no connection between the TOC diurnal variability and the aerosol load at three different sites. Antón et al (2010a) and Raj et al (2004) found that the observed diurnal TOC variations have different seasonal behaviour.…”

“…The diurnal variation of TOC has not been extensively investigated and in most studies it has been examined only for short periods during campaigns. In Table 6.1 (adopted from Silva, 2013) there is a summary of these studies. From Table 6.1 it is evident that diurnal variations in TOC, ranging from 4 to 40 DU have been detected by some Brewer spectrophotometers.…”