The comparison of IR and MW ground-based measurements of total precipitable water

Water vapor is one of the basic climate gases playing a key role in various processes at different altitudes of the Earth’s atmosphere. An intercomparison and validation of different total precipitable water (TPW) measurement methods are important for determining the true accuracy of these methods, the shared use of data from multiple sources, the creation of data archives of different measurements, etc. In this paper, the TPW values obtained from measurements of solar IR spectral radiation (~8–9 μm absorption band) and thermal MW radiation of the atmosphere (1.35 cm absorption line) for 138 days of observation are compared. Measurements have been carried out from March 2013 to June 2014 at Peterhof station of the St. Petersburg State University in (59.88° N, 29.82° E). It is shown that MW measurements usually give higher TPW values than IR measurements. The bias between the two methods varies from 1 to 8% for small and large TPW values, respectively. With increasing TPW values, the bias reduces and for TPW > 1 cm it is ~1%. Standard deviation (SD) between the two methods reaches 7% for TPW < 0.4 cm and 3–5% for TPW > 1 cm. These data show the high quality of both remote sensing methods. Moreover, the IR measurements have a higher accuracy than MW measurements for small TPW values.     

Analysis of variability of the CO, NO2, and O3 contents in the troposphere near St. Petersburg

The space-time variability of the fields of CO, NO₂, and O₃ concentrations and contents in the troposphere of northwestern Russia is analyzed on the basis of experimental data and the results of numerical modeling. The influence that the St. Petersburg emission has on the concentrations and contents of CO, NO₂, and O₃ in the troposphere is estimated for March 2006. A comparison of the measurements of the total CO content and the tropospheric NO₂ content with the results of modeling showed a qualitative and, in come cases, quantitative agreement between the results of calculations and experimental data. When synoptic conditions are determined, the St. Petersburg train can be detected at a distance of more than 300 km, which can affect the atmospheric air quality in adjacent countries.     

Ground-based measurements of total ozone content by the infrared method

To interpret the ground-based measurements of the spectra of direct solar infrared radiation with the help of a Brucker Fourier-spectrometer, a technique for determining the total ozone content (TOC) was developed and implemented. The TOC was determined using six spectral intervals of an ozone-absorption band of 9.6 μm and the shortwave panel of a carbon-dioxide-absorption band of 15 μm, where the impact of other atmospheric parameters on the measured solar radiation was reduced to a minimum. The potential errors of the infrared method for determining the TOC for the chosen spectral scheme with the influence of measurement errors and vertical profiles of temperature are less than 1% for different signal-to-noise ratios and zenith angles of the sun. We analyzed 269 high-resolution (0.005–0.008 cm^?1) spectra of solar infrared radiation measured in Peterhof over 52 days from March to November, 2009. The resulting values of TOC were compared with the results of independent ground-based TOC measurements in Voeikovo (Main Geophysical Observatory) using a Dobson spectrophotometer and an M-124 ozonometer, as well as with the Ozone Monitoring Instrument (OMI) satellite data. The mean errors between the results of TOC measurements with the help of the three ground-based probes constitute no more than 0.4%. The rms errors between data obtained by the Brucker spectrometer and the given satellite and ground-based probes constitute 3–4%. A comparison between different series of measurements indicated that the upper estimate for the error of TOC measurements by the Brucker spectrometer was 2.5–3% (when the possible spatial and temporal errors in measurements are disregarded). An analysis of the diurnal variations in the TOC measurements for stable atmospheric conditions yields an upper estimate of ～3 DU (around 1%) for the random component of error in TOC measurements by the Brucker spectrometer.     

Ground-Based Field Measurements and Calibrations of a New Satellite Spectrometer for Monitoring the Earth’s Ozone Layer

Izvestiya, Atmospheric and Oceanic Physics - The results obtained from test ground-based measurements with a new satellite instrument for mo-nitoring the Earth’s ozone layer are considered....     

Integral emission of nitrogen oxides from the territory of St. Petersburg based on the data of mobile measurements and numerical simulation results

The results of spectroscopic measurements of tropospheric NO₂ content performed on a closed route along the circular road around the city of St. Petersburg in 2012, 2014, and 2015 are presented. A procedure for determining the integral emission of NO _x based on the data of measurements on the route enveloping the sources under study is described. An analysis of the experimental data together with the results of a numerical simulation of air pollutant dispersion (the HYSPLIT model) provided an estimate of the total volume of NO _x emitted by all sources located inside the circular road. The average emission rate of NO _x according to the sources of the megacity of St. Petersburg is 57000 t/yr, which correlates satisfactorily with the official data of a municipal inventory of the sources of air pollution (62000–63 000 t/yr).     

Variations in the column-average dry-air mole fractions of CO2 in the vicinity of St. Petersburg

The results obtained from ground-based spectroscopic measurements of column-average dry-air mole fractions of CO₂ in the atmosphere over the St. Petersburg region are given for the period April 2009–October 2011 (～900 measurement runs, 151 measurement days). These results show significant variations in the CO₂ mixing ratio in the atmosphere over the St. Petersburg region. The minimum value of this mixing ratio (373.1 ppm) was observed on April 27, 2011, and its maximum value (420.8 ppm) was observed on February 10, 2010. The typical seasonal behavior of the CO₂ mixing ratio with its summer minimum was observed in 2009. In July 2010 and 2011, the values of the CO₂ mixing ratio increased apparently due to high air temperatures. In 2010 an additional contribution to this increase in the CO₂ mixing ratio could have been made by strong natural fires.     

Ground-based measurements of total column of hydrogen chloride in the atmosphere near St. Petersburg

We present ground-based spectroscopic measurements of the total hydrogen chloride in the atmosphere of Peterhof near St. Petersburg from April 2009 to March 2012. The well-known computer code SFIT-2 (Zephyr-2) was used to interpret the spectra of the solar IR radiation. The random and systematic errors of total column (TC) HCl measurements did not exceed 3.8 and 4.5%. The seasonal behavior of TC HCl in Peterhof is characterized by the presence of a maximum in March–April and a minimum in October–November. There are also extremely small TC HCl values in January–February. The time behavior obtained for Peterhof agrees well with data from nearest stations in the NDACC international network. The ground-based measurements of the TC HCl were compared with satellite measurements with the help of ACE-FTS and MLS instruments. The direct comparisons of coincident (within a day) and collocated (within 500 km) satellite and ground-based measurements showed a correspondence of results within their total errors.     

Estimation of Nocturnal Area Fluxes of Carbon Cycle Gases in Saint Petersburg Suburbs

Carbon dioxide, methane, and carbon monoxide are the carbon cycle gases, the data on their emissions are needed when monitoring air pollution and developing methods for reducing anthropogenic emissions to the atmosphere and for climate forecasting. The estimates of nocturnal area fluxes for CO₂, CH₄, and CO presented for a suburb of Saint Petersburg (Peterhof) are obtained using the box model and continuous observations of concentration of these gases. The mean values of CH₄, CO₂, and CO fluxes estimated for Peterhof for 2014–2015 are 44 ± 27, 6100 ± 4000, and 90 ± 100 t/(km² year), respectively. The intensity of the CO area flux has pronounced seasonal variations characterized by the maximum of ~(160 ± 120) t/(km² year) in November—February and by the minimum of ~(30 ± 20) t/(km² year) in June-July. The analysis of the ratio of CO/CO₂ fluxes identified the main types of anthropogenic sources typical of Peterhof: motor transport, natural gas combustion, and the use of wood stoves for the heating of private low-rise buildings (in the cold season).     

Experimental Estimates of Integral Anthropogenic CO2 Emissions in the City of St. Petersburg

Izvestiya, Atmospheric and Oceanic Physics - The increase in the content of greenhouse gases (CO2, CH4, N2O, etc.) in the Earth’s atmosphere is changing the radiation balance and leading to...     

Variability of the total column amounts of climate influencing gases obtained from ground-based high resolution spectroscope measurements

Doklady Earth Sciences -