The IPCC has identified the indirect aerosol effect as the biggest uncertainty in the Earth's climate system. For this reason, efforts are being made to measure aerosols and the associated effect on the climate. Antarctica is often used to reveal changes in the global background. One of the characteristics enabling to separate aerosol of the local origin from the background level is the aerosol vertical profile. A MAX-DOAS technique is among the approaches that can give information on the aerosol vertical distribution.
The paper presents instrumentation and preliminary results of aerosol measurements which were conducted in eastern Antarctica, near the Russian station "Progress" (69°22S 76°23E, Larsemann Hills). The aerosol measurements were performed using a MAX-DOAS instrument called MARS-B originally designed by NOMREC of BSU. The MARS-B instrument records spectra of the scattered sunlight in a range of the elevation angles of 0°–90° in the UV and visible range of 341-426 and 416-500 nm with FWHM=0.32 nm.
To retrieve aerosol extinction, we used its influence on the optical depth of the collision complex O2-O2 (or O4) of the molecular oxygen O2. Aerosol extinction was obtained for the wavelengths of 370 and 458 nm. The MAX-DOAS aerosol measurements were performed in January and February, 2014, and were further compared with Cimel-CE318 solar photometer data for clear days. Features of two data series are discussed in brief.
An instrument for measuring atmospheric trace gases by DOAS method using scattered solar radiation was developed in
A.M.Obukhov IAP RAS. The instrument layout is based on the lab Shamrock 303i spectrograph supplemented by 2-port
radiation input system employing optical fiber. Optical ports may be used with a fixed telescope or with a scanning
In September 2016 the IAP instrument participated in the 2nd Cabauw Intercomparison of Nitrogen Dioxide Measuring
Instruments (CINDI-2) campaign, held in the Netherlands. About 40 instruments from 26 different organizations
performed DOAS measurement of NO2, HCHO and other trace gases during the campaign.
During the campaign the optical ports of IAP instrument had telescopes A and B with similar field of view of about 0.3°.
Telescope A was always directed to the zenith. Telescope B was directed at 5° elevation angle. Two gratings were
installed in the spectrometer. They provide different spectral resolution (FWHM ~0.4 and 0.8 nm respectively) and
spectral window width (~70 and ~140 nm respectively). During CINDI-2 campaign we performed test measurements in
UV and visible wavelength ranges to investigate instrument stability and retrieval errors of NO2 and HCHO contents. We
test four operational mode of the instrument in which we used fixed grating position in UV or visible spectral region, or
rotate grating between UV and visible, or change gratings using a turret.
Here we present preliminary results of comparison of gas content measured by IAP instrument with the median gas
content obtained on the basis of measurements of all groups participated in CINDI-2 campaign. The main goal of the
study was the detailed comparison of all four modes of our instrument and understanding of probable biases and errors
typical for these modes. It was found that rotation of grating turret does not significantly affected on quality of NO2
DSCD retrieval and is much more significant for HCHO DSCD retrieval.