We present airborne measurements of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), equivalent black carbon (EBC) and ultra fine particles over North-Eastern Siberia in July 2008 performed ...during the YAK-AEROSIB/POLARCAT experiment. During a "golden day" (11 July 2008) a number of biomass burning plumes were encountered with CO mixing ratio enhancements of up to 500 ppb relative to a background of 90 ppb. Number concentrations of aerosols in the size range 3.5–200 nm peaked at 4000 cm−3 and the EBC content reached 1.4 μg m−3. These high concentrations were caused by forest fires in the vicinity of the landing airport in Yakutsk where measurements in fresh smoke could be made during the descent. We estimate a combustion efficiency of 90 ± 3% based on CO and CO2 measurements and a CO emission factor of 65.5 ± 10.8 g CO per kilogram of dry matter burned. This suggests a potential increase in the average northern hemispheric CO mixing ratio of 3.0–7.2 ppb per million hectares of Siberian forest burned. For BC, we estimate an emission factor of 0.52 ± 0.07 g BC kg−1, comparable to values reported in the literature. The emission ratio of ultra-fine particles (3.5–200 nm) was 26 cm−3 (ppb CO)−1, consistent with other airborne studies. The transport of identified biomass burning plumes was investigated using the FLEXPART Lagrangian model. Based on sampling of wildfire plumes from the same source but with different atmospheric ages derived from FLEXPART, we estimate that the e-folding lifetimes of EBC and ultra fine particles (between 3.5 and 200 nm in size) against removal and growth processes are 5.1 and 5.5 days respectively, supporting lifetime estimates used in various modelling studies.
In this paper, we provide a detailed comparison between carbon monoxide (CO) data measured by the Infrared Atmospheric Sounding Interferometer (IASI)/MetOp and aircraft observations over the Arctic. ...The CO measurements were obtained during North American (NASA ARCTAS and NOAA ARCPAC) and European campaigns (POLARCAT-France, POLARCAT-GRACE and YAK-AEROSIB) as part of the International Polar Year (IPY) POLARCAT activity in spring and summer 2008. During the campaigns different air masses were sampled including clean air, polluted plumes originating from anthropogenic sources in Europe, Asia and North America, and forest fire plumes originating from Siberia and Canada. The paper illustrates that CO-rich plumes following different transport pathways were well captured by the IASI instrument, in particular due to the high spatial coverage of IASI. The comparison between IASI CO total columns, 0-5 km partial columns and profiles with collocated aircraft data was achieved by taking into account the different sensitivity and geometry of the sounding instruments. A detailed analysis is provided and the agreement is discussed in terms of information content and surface properties at the location of the observations. For profiles, the data were found to be in good agreement in spring with differences lower than 17%, whereas in summer the difference can reach 20% for IASI profiles below 8 km for polluted cases. For total columns the correlation coefficients ranged from 0.15 to 0.74 (from 0.47 to 0.77 for partial columns) in spring and from 0.26 to 0.84 (from 0.66 to 0.88 for partial columns) in summer. A better agreement is seen over the sea in spring (0.73 for total column and 0.78 for partial column) and over the land in summer (0.69 for total columns and 0.81 for partial columns). The IASI vertical sensitivity was better over land than over sea, and better over land than over sea ice and snow allowing a higher potential to detect CO vertical distribution during summer.
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Based on the results of a comprehensive experiment conducted in September 2020, the spatial distribution of the following trace gases over the seas of the Russian Arctic are analyzed: carbon ...monoxide (CO), ozone (O
3
), nitrogen oxide and dioxide (NO and NO
2
), and sulfur dioxide (SO
2
). It is shown that the gas concentrations in the surface air layer over the seas (at an altitude of 200 m) vary in the range 18–36 ppb for O
3
, 60–130 ppb for CO, 0.005–0.12 ppb for NO, 0.10–1.00 ppb for NO
2
, and 0.06–0.80 ppb for SO
2
. The distribution of the gases over the water area is heterogeneous over most seas, which most likely reflects differences in their uptake by the ocean and peculiarities of transport from the continent.
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We analyze the spatial distribution of carbon dioxide over the seas of the Russian Arctic based on the results of the comprehensive experiment conducted in September 2020. It turned out that during ...the experiment, the concentration of CO
2
increased from west to east. The minimum of 396 ppm was over the Barents Sea, and the maximum of 4106 ppm was over the Chukchi Sea. The difference between the concentrations at an altitude of 200 m and in the free troposphere attained 156 ppm over the Barents Sea and decreased to 56 ppm over the Laptev Sea. Over the eastern seas, the difference became generally positive, which was associated with the air transfer from Alaska. Above the waters of most seas, the distribution of carbon dioxide was horizontally heterogeneous, which showed the regional features of its assimilation by the ocean and transfer from the continent.
Ozone data retrieved in the Arctic region from infrared radiance spectra recorded by the Infrared Atmospheric Sounding Interferometer (IASI) on board the MetOp-A European satellite are presented. ...They are compared with in situ and lidar observations obtained during a series of aircraft measurement campaigns as part of the International Polar Year POLARCAT activities in spring and summer 2008. Different air masses were sampled during the campaigns including clean air, polluted plumes originating from anthropogenic sources, forest fire plumes from the three northern continents, and stratospheric-influenced air masses. The comparison between IASI O3 0-8 km, 0-12 km partial columns and profiles with collocated aircraft observations is achieved by taking into account the different sensitivity and geometry of the sounding instruments. A detailed analysis is provided and the agreement is discussed in terms of vertical sensitivity and surface properties at the location of the observations. Overall, IASI O3 profiles are found to be in relatively good agreement with smoothed in situ and lidar profiles in the free troposphere with differences of less than 40% (25% over sea for both seasons) and 10%, respectively. The correlation between IASI O3 retrieved partial columns and the smoothed aircraft partial columns is good with DC-8 in situ data in spring over North America (r = 0.68), and over Greenland with ATR-42 lidar measurements in summer (r = 0.67). Correlations with other data are less significant highlighting the difficulty of IASI to capture precisely the O3 variability in the Arctic upper troposphere and lower stratosphere (UTLS). This is particularly noted in comparison with the 0-12 km partial columns. The IASI 0-8 km partial columns display a low negative bias (by less than 26% over snow) compared to columns derived from in situ measurements. Despite the relatively high biases of the IASI retrievals in the Arctic UTLS, our analysis shows that IASI can be used to identify, using O3 / CO ratios, stratospheric intrusions.
We present the configuration of the Météo-France Chemistry and Transport Model (CTM) MOCAGE-Climat that will be dedicated to the study of chemistry and climate interactions. MOCAGE-Climat is a ...state-of-the-art CTM that simulates the global distribution of ozone and its precursors (82 chemical species) both in the troposphere and the stratosphere, up to the mid-mesosphere (~70 km). Surface processes (emissions, dry deposition), convection, and scavenging are explicitly described in the model that has been driven by the ECMWF operational analyses of the period 2000–2005, on T21 and T42 horizontal grids and 60 hybrid vertical levels, with and without a procedure that reduces calculations in the boundary layer, and with on-line or climatological deposition velocities. Model outputs have been compared to available observations, both from satellites (TOMS, HALOE, SMR, SCIAMACHY, MOPITT) and in-situ instrument measurements (ozone sondes, MOZAIC and aircraft campaigns) at climatological timescales. The distribution of long-lived species is in fair agreement with observations in the stratosphere putting aside the shortcomings associated with the large-scale circulation. The variability of the ozone column, both spatially and temporarily, is satisfactory. However, because the Brewer-Dobson circulation is too fast, too much ozone is accumulated in the lower to mid-stratosphere at the end of winter. Ozone in the UTLS region does not show any systematic bias. In the troposphere better agreement with ozone sonde measurements is obtained at mid and high latitudes than in the tropics and differences with observations are the lowest in summer. Simulations using a simplified boundary layer lead to larger ozone differences between the model and the observations up to the mid-troposphere. NOx in the lowest troposphere is in general overestimated, especially in the winter months over the Northern Hemisphere, which may result from a positive bias in OH. Dry deposition fluxes of O3 and nitrogen species are within the range of values reported by recent inter-comparison model exercises. The use of climatological deposition velocities versus deposition velocities calculated on-line had greatest impact on HNO3 and NO2 in the troposphere.
This paper analyses a stratospheric injection by deep convection of biomass fire emissions over North America (Alaska, Yukon and Northwest Territories) on 24 June 2004 and its long-range transport ...over the eastern coast of the United States and the eastern Atlantic. The case study is based on airborne MOZAIC observations of ozone, carbon monoxide, nitrogen oxides and water vapour during the crossing of the southernmost tip of an upper level trough over the Eastern Atlantic on 30 June and on a vertical profile over Washington DC on 30 June, and on lidar observations of aerosol backscattering at Madison (University of Wisconsin) on 28 June. Attribution of the observed CO plumes to the boreal fires is achieved by backward simulations with a Lagrangian particle dispersion model (FLEXPART). A simulation with the Meso-NH model for the source region shows that a boundary layer tracer, mimicking the boreal forest fire smoke, is lofted into the lowermost stratosphere (2–5 pvu layer) during the diurnal convective cycle at isentropic levels (above 335 K) corresponding to those of the downstream MOZAIC observations. It is shown that the order of magnitude of the time needed by the parameterized convective detrainment flux to fill the volume of a model mesh (20 km horizontal, 500 m vertical) above the tropopause with pure boundary layer air would be about 7.5 h, i.e. a time period compatible with the convective diurnal cycle. Over the area of interest, the maximum instantaneous detrainment fluxes deposited about 15 to 20% of the initial boundary layer tracer concentration at 335 K. According to the 275-ppbv carbon monoxide maximum mixing ratio observed by MOZAIC over Eastern Atlantic, such detrainment fluxes would be associated with a 1.4–1.8 ppmv carbon monoxide mixing ratio in the boundary layer over the source region.
We analysed results of three intensive aircraft campaigns above Siberia (April and September 2006, August 2007) with a total of ~70 h of continuous CO2, CO and O3 measurements. The flight route ...consists of consecutive ascents and descents between Novosibirsk (55° N, 82° E) and Yakutsk (62° N, 129° E). We performed retroplume calculations with the Lagrangian particle dispersion model FLEXPART for many short segments along the flight tracks. To reduce the extremely rich information on source regions provided by the model calculation into a small number of distinct cases, we performed a statistical clustering - to our knowledge for the first time - into potential source regions of the footprint emission sensitivities obtained from the model calculations. This technique not only worked well to separate source region influences but also resulted in clearly distinct tracer concentrations for the various clusters obtained. High CO and O3 concentrations were found associated with agricultural fire plumes originating from Kazakhstan in September 2006. A statistical analysis indicates that summer uptake of CO2 is largely explained (~50% of variance) by air mass exposure to uptake by Siberian and sub-arctic ecosystems. This resulted in an average 5 to 10 ppm difference with overlaying air masses. Stratosphere-troposphere exchange is found to strongly influence the observed O3 mixing ratios in spring, but not in summer. European emissions contributed to high O3 concentrations above Siberia in April 2006 and August 2007, while emissions from North Eastern China also contributed to higher O3 mixing ratios in summer, but tend to lower mixing ratios in spring, when the airmass aerosol burden is important. In the lower troposphere, large-scale deposition processes in the boreal and sub-arctic boundary layer is a large O3 sink, resulting in a ~20 ppb difference with overlaying air masses. Lagrangian footprint clustering is very promising and could also be advantageously applied to the interpretation of ground based measurements including calculation of tracers' sources and sinks.
Ozone data retrieved in the Arctic region from infrared radiance spectra recorded by the Infrared Atmospheric Sounding Interferometer (IASI) on board the MetOp-A European satellite are presented. ...They are compared with in situ and lidar observations obtained during a series of aircraft measurement campaigns as part of the International Polar Year POLARCAT activities in spring and summer 2008. Different air masses were sampled during the campaigns including clean air, polluted plumes originating from anthropogenic sources, forest fire plumes from the three northern continents, and stratospheric-influenced air masses. The comparison between IASI O3 0–8 km, 0–12 km partial columns and profiles with collocated aircraft observations is achieved by taking into account the different sensitivity and geometry of the sounding instruments. A detailed analysis is provided and the agreement is discussed in terms of vertical sensitivity and surface properties at the location of the observations. Overall, IASI O3 profiles are found to be in relatively good agreement with smoothed in situ and lidar profiles in the free troposphere with differences of less than 40% (25% over sea for both seasons) and 10%, respectively. The correlation between IASI O3 retrieved partial columns and the smoothed aircraft partial columns is good with DC-8 in situ data in spring over North America (r = 0.68), and over Greenland with ATR-42 lidar measurements in summer (r = 0.67). Correlations with other data are less significant highlighting the difficulty of IASI to capture precisely the O3 variability in the Arctic upper troposphere and lower stratosphere (UTLS). This is particularly noted in comparison with the 0–12 km partial columns. The IASI 0–8 km partial columns display a low negative bias (by less than 26% over snow) compared to columns derived from in situ measurements. Despite the relatively high biases of the IASI retrievals in the Arctic UTLS, our analysis shows that IASI can be used to identify, using O3 / CO ratios, stratospheric intrusions.
Data on the vertical distribution of gaseous and aerosol composition of air, measured onboard the Tu-134 Optic airborne laboratory in October 2014 over the Kara Sea and coastal areas of the Russian ...Arctic, are presented. We revealed the specific features of the altitude distributions of CO
2
and aerosol over the Kara Sea as compared to continental conditions. No significant deviations from continental distributions are found for CH
4
, CO, and O
3
.
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