scholarly journals Wavelength calibration of Brewer spectrophotometer using a tuneable pulsed laser and implications to the Brewer ozone retrieval

2018 ◽  
Author(s):  
Alberto Redondas ◽  
Saulius Nevas ◽  
Alberto Berjón ◽  
Meelis-Mait Sildoja ◽  
Sergio Fabian León-Luis ◽  
...  
Keyword(s):  
Standard Procedure ◽  
Pulsed Laser ◽  
Laser Source ◽  
Ozone Absorption ◽  
Total Column Ozone ◽  
Wavelength Calibration ◽  
Brewer Spectrophotometer ◽  
Wavelength Scale ◽  
Column Ozone ◽  
Total Column

Abstract. In this contribution we present the wavelength calibration of the traveling reference Brewer spectrometer of the Regional Brewer Calibration Center for Europe (RBCC-E) at PTB in Braunschweig, Germany. The wavelength calibration is needed for the calculation of the ozone absorption coefficients used by the Brewer ozone algorithm. In order to validate the standard procedure for determining Brewer’s wavelength scale, a calibration has been performed by using a tuneable laser source at PTB in the framework of the EMRP project ENV59 ATMOZ Traceability for the total column ozone. Here we compare these results to those of the standard procedure for the wavelength calibration of the Brewer instrument. Such a comparison allows validating the standard methodology used for measuring the ozone absorption coefficient with respect to several assumptions. The results of the laser-based calibrations reproduces those obtained by the standard operational methodology and shows that there is a underestimation of 0.8 % due the use of the parametrized slit functions.

scholarly journals Wavelength calibration of Brewer spectrophotometer using a tunable pulsed laser and implications to the Brewer ozone retrieval

2018 ◽  
Vol 11 (6) ◽  
pp. 3759-3768 ◽  
Author(s):  
Alberto Redondas ◽  
Saulius Nevas ◽  
Alberto Berjón ◽  
Meelis-Mait Sildoja ◽  
Sergio Fabian León-Luis ◽  
...  
Keyword(s):  
Standard Procedure ◽  
Tunable Laser ◽  
Laser Source ◽  
Absorption Coefficients ◽  
Ozone Absorption ◽  
Total Column Ozone ◽  
Wavelength Calibration ◽  
Wavelength Scale ◽  
Column Ozone ◽  
Total Column

Abstract. In this contribution we present the wavelength calibration of the travelling reference Brewer spectrometer of the Regional Brewer Calibration Center for Europe (RBCC-E) at PTB in Braunschweig, Germany. The wavelength calibration is needed for the calculation of the ozone absorption coefficients used by the Brewer ozone algorithm. In order to validate the standard procedure for determining Brewer's wavelength scale, a calibration has been performed by using a tunable laser source at PTB in the framework of the EMRP project ENV59 ATMOZ “Traceability for the total column ozone”. Here we compare these results to those of the standard procedure for the wavelength calibration of the Brewer instrument. Such a comparison allows validating the standard methodology used for measuring the ozone absorption coefficient with respect to several assumptions. The results of the laser-based calibrations reproduces those obtained by the standard operational methodology and shows that there is an underestimation of 0.8 % of the ozone absorption coefficients due to the use of the parametrized slit functions.

scholarly journals Total column ozone measurements by the Dobson spectrophotometer at Belsk (Poland) for the period 1963–2019: homogenization and adjustment to the Brewer spectrophotometer

2021 ◽  
Vol 13 (9) ◽  
pp. 4425-4436
Author(s):  
Janusz W. Krzyścin ◽  
Bonawentura Rajewska-Więch ◽  
Janusz Jarosławski
Keyword(s):  
Weather Conditions ◽  
Total Column Ozone ◽  
Long Term Stability ◽  
Ultraviolet Range ◽  
Brewer Spectrophotometer ◽  
World Standard ◽  
Column Ozone ◽  
Total Column ◽  
Dobson Spectrophotometer

Abstract. The total column ozone (TCO3) measurements by the Dobson spectrophotometer (serial no. 84) have been carried out at Belsk station (51∘50′ N, 20∘47′ E), Poland, since 23 March 1963. In total, ∼115 000 intraday manual observations were made by 31 December 2019. These observations were performed for different combinations of double wavelength pairs in the ultraviolet range and observation types, i.e., direct sun (DS), zenith blue (ZB), and zenith cloudy (ZC) depending on weather conditions. The long-term stability of the instrument was supported by frequent (almost every 4 years) intercomparisons with the world standard spectrophotometer. Trend analyses, based on the monthly and yearly averaged TCO3, can be carried out without any additional corrections to the intraday values. To adjust these data to the Brewer spectrophotometer observations, which were also performed at Belsk, a procedure is proposed to account for less accurate Dobson observations under low solar elevation, presence of clouds, and the temperature dependence of ozone absorption. The adjusted time series shows that the Brewer–Dobson monthly averaged differences are in the range of about ±0.5 %. The intraday TCO3 database, divided into three periods (1963–1979, 1980–1999, and 2000–2019), is freely available at https://doi.org/10.1594/PANGAEA.919378 (Rajewska-Więch et al., 2020).

scholarly journals Consistency of total column ozone measurements between the Brewer and Dobson spectroradiometers of the LKO Arosa and PMOD/WRC Davos

2021 ◽  
Author(s):  
Julian Gröbner ◽  
Herbert Schill ◽  
Luca Egli ◽  
René Stübi
Keyword(s):  
Time Series ◽  
Cross Sections ◽  
Rayleigh Scattering ◽  
Absorption Cross ◽  
Ozone Absorption ◽  
Total Column Ozone ◽  
Measured Line ◽  
Column Ozone ◽  
Scattering Cross Sections ◽  
Total Column

Abstract. Total column ozone measured by Brewer and Dobson spectroradiometers at Arosa and Davos, Switzerland, have systematic seasonal variations of around 1.5 % using the standard operational data processing. Most of this variability can be attributed to the temperature sensitivity of approx. +0.1 %/K of the ozone absorption coefficient of the Dobson spectroradiometer (in this study D101). While the currently used Bass&Paur ozone absorption cross-sections produce inconsistent results for Dobson and Brewer, the use of the ozone absorption cross-sections from Serdyuchenko et al. (2013) in conjunction with an effective ozone temperature dataset produces excellent agreement between the investigated four Brewers (of which two double Brewers), and Dobson D101. Even though other ozone absorption cross-sections available in the literature are able to reduce the seasonal variability, all of those investigated produce systematic biases in total column ozone between Brewer and Dobson of 1.1 % to 3.1 %. The highest consistency of total column ozone from Brewers and Dobson D101 at Arosa/Davos of 0.1 % is obtained by applying the Rayleigh scattering cross-sections from Bodhaine et al. (1999), the ozone absorption cross-sections from Serdyuchenko et al. (2013), the effective ozone temperature from either ozonesondes or ECMWF, and the measured line-spread functions of Brewer and Dobson. The variability between Brewer and Dobson for single measurements of 0.9 % can be reduced to less than 0.5 % for monthly means and 0.3 % on yearly means. As show here, the proposed methodology produces consistent total column ozone datasets between Brewer and Dobson spectroradiometers of better than 1 %. For colocated Brewer and Dobson spectroradiometers, as is the case for the Arosa/Davos total column ozone times series, this allows the merging of these two distinct datasets to produce a homogeneous time series of total column ozone measurements. Furthermore, it guarantees the long-term future of this longest total column ozone time-series, by proposing a methodology how to eventually replace the ageing Dobson spectroradiometer with the state-of-the art Brewer spectroradiometer.

scholarly journals Total column ozone measurements by the Dobson spectrophotometer at Belsk (Poland) for the period 1963–2019: homogenization and adjustment to the Brewer spectrophotometer

2021 ◽  
Author(s):  
Janusz W. Krzyścin ◽  
Bonawentura Rajewska-Więch ◽  
Janusz Jarosławski
Keyword(s):  
Weather Conditions ◽  
Total Column Ozone ◽  
Long Term Stability ◽  
Brewer Spectrophotometer ◽  
World Standard ◽  
Column Ozone ◽  
Total Column ◽  
Dobson Spectrophotometer ◽  
Uv Range

Abstract. The total column ozone (TCO3) measurements by the Dobson spectrophotometer #84 have been carried out at Belsk (51°50', 20°47'), Poland, since March 23, 1963. In total, ~115,000 intra-day manual observations have been taken up to December 31, 2019. These observations were made for various combinations of double wavelength pairs in UV range (AD, CD) and the observation category, i.e., direct Sun, zenith blue, and zenith cloudy depending on the weather conditions. The long-term stability of the instrument was supported by frequent (~almost every 4 yr.) intercomparisons with the world standard spectrophotometers. Trend analyses, based on the monthly and yearly averaged TCO3, can be carried out without any additional corrections to the intraday values. To adjust this data to the Brewer spectrophotometer observations also performed at Belsk, a procedure is proposed to account for: less accurate Dobson observations under low solar elevation, presence of clouds, and sensitivity of the ozone absorption on temperature. The adjusted time series shows that the Brewer-Dobson monthly averaged differences are in the range of about ±0.5 %. The intra-day TCO3 data base, divided into three periods (1963–1979, 1980–1999, and 2000–2019), is freely available at https://doi.pangaea.de/10.1594/PANGAEA.919378 (Rajewska-Więch et al., 2020).

scholarly journals Optical Characterization of Three Reference Dobsons in the ATMOZ Project – Verification of G. M. B. Dobson's Original Specifications

2017 ◽  
Author(s):  
Ulf Köhler ◽  
Saulius Nevas ◽  
Glen McConville ◽  
Robert Evans ◽  
Marek Smid ◽  
...  
Keyword(s):  
Cross Sections ◽  
Ozone Absorption ◽  
Total Column Ozone ◽  
Satellite Validation ◽  
World Standard ◽  
Column Ozone ◽  
Ozone Column ◽  
Positive Effect ◽  
Total Column

Abstract. Three reference Dobsons (regional standards Dobsons No. 064 Hohenpeissenberg – Germany and No. 074 Hradec Kralove – Czech Republic and primary = world standard Dobson No. 083 Boulder – USA) were optically characterized at PTB (Physikalisch-Technische Bundesanstalt in Braunschweig) in 2015 and at CMI (Czech Metrology Institute in Prague) in 2016 within the EMRP ENV 059 project Traceability for the total column ozone. Bandpass functions and the related parameters of the instruments were measured and compared with G. M. B. Dobson's specification in his handbook. A predominantly good match of the bandpass functions and the peak (centroid) wavelengths of D083, D064 and D074 with the nominal values could be observed. Slightly larger deviations from the nominal Dobson data can be seen in the longer wavelengths, especially in the D-wavelength. As consequence of these findings the differences of the derived Effective Absorptions Coefficients (EACs) for ozone to Dobson's nominal ones are not too large in both old Bass-Paur (BP) and new IUP-ozone absorption cross sections. Their consideration in the calculation of the total ozone column (TOC) leads to improvements of significantly less than ±1 % in the AD- and between −1 % and −2 % in the CD-wavelengths pairs. Besides this positive effect of the achievement of data with higher quality needed for trend analyses and satellite validation, it will be possible to explain uncommon behaviours of field Dobsons during calibration services.

scholarly journals Spatial mapping of ground-based observations of total ozone

2015 ◽  
Vol 8 (10) ◽  
pp. 4487-4505 ◽  
Author(s):  
K.-L. Chang ◽  
S. Guillas ◽  
V. E. Fioletov
Keyword(s):  
Spatial Interpolation ◽  
Stochastic Partial Differential Equation ◽  
Positive Impact ◽  
The Novel ◽  
Total Column Ozone ◽  
Column Ozone ◽  
Source Of Information ◽  
Total Column ◽  
Ozone Levels

Abstract. Total column ozone variations estimated using ground-based stations provide important independent source of information in addition to satellite-based estimates. This estimation has been vigorously challenged by data inhomogeneity in time and by the irregularity of the spatial distribution of stations, as well as by interruptions in observation records. Furthermore, some stations have calibration issues and thus observations may drift. In this paper we compare the spatial interpolation of ozone levels using the novel stochastic partial differential equation (SPDE) approach with the covariance-based kriging. We show how these new spatial predictions are more accurate, less uncertain and more robust. We construct long-term zonal means to investigate the robustness against the absence of measurements at some stations as well as instruments drifts. We conclude that time series analyzes can benefit from the SPDE approach compared to the covariance-based kriging when stations are missing, but the positive impact of the technique is less pronounced in the case of drifts.

scholarly journals Characterizing ozone throughout the atmospheric column over the tropical Andes from in situ and remote sensing observations

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
María Cazorla ◽  
René Parra ◽  
Edgar Herrera ◽  
Francisco Raimundo da Silva
Keyword(s):  
Boundary Layer ◽  
Atmospheric Ozone ◽  
Tropical Andes ◽  
Total Column Ozone ◽  
Study Region ◽  
Boundary Layer Height ◽  
Mixing Ratios ◽  
The Andes ◽  
Column Ozone ◽  
Total Column

In this study, we characterize atmospheric ozone over the tropical Andes in the boundary layer, the free troposphere, and the stratosphere; we quantify each contribution to total column ozone, and we evaluate the performance of the multi-sensor reanalysis (MSR2) in the region. Thus, we present data taken in Ecuador and Peru (2014–2019). The contribution from the surface was determined by integrating ozone concentrations measured in Quito and Cuenca (Ecuador) up to boundary layer height. In addition, tropospheric and stratospheric column ozone were quantified from ozone soundings (38) launched from Quito during the study time period. Profiles were compared against soundings at Natal (SHADOZ network) for being the closest observational reference with sufficient data in 2014–2019. Data were also compared against stratospheric mixing ratios from the Aura Microwave Limb Sounder (Aura MLS). Findings demonstrate that the stratospheric component of total column ozone over the Andes (225.2 ± 8.9 Dobson Units [DU]) is at similar levels as those observed at Natal (223.3 ± 8.6 DU), and observations are comparable to Aura MLS data. In contrast, the tropospheric contribution is lower over the Andes (20.2 ± 4.3 DU) when compared to Natal (35.4 ± 6.4 DU) due to a less deep and cleaner troposphere. From sounding extrapolation of Quito profiles down to sea level, we determined that altitude deducts about 5–7 DU from the total column, which coincides with a 3%–4% overestimation of the MSR2 over Quito and Marcapomacocha (Peru). In addition, when MSR2 data are compared along a transect that crosses from the Amazon over Quito, the Ecuadorian coast side, and into the Pacific, observations are not significantly different among the three first locations. Results point to coarse reanalysis resolution not being suitable to resolve the formidable altitude transition imposed by the Andes mountain chain. This work advances our knowledge of atmospheric ozone over the study region and provides a robust time series of upper air measurements for future evaluations of satellite and reanalysis products.

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