•H2O mixing ratio and the cloud top altitudes were measured by SPICAV IR on VEx over 8.5 years.•The average H2O mixing ratio equals 5–7ppm at effective altitudes of 60–62km.•Two maxima in the ...latitudinal distribution of H2O were observed: near equator and near the pole.•A asymmetry of H2O longitudinal distribution has been observed in low latitudes.•No prominent long-term nor local time variations of H2O and the cloud tops were detected.
SPICAV VIS-IR spectrometer on-board the Venus Express mission measured the H2O abundance above Venus’ clouds in the 1.38µm band, and provided an estimation of the cloud top altitude based on CO2 bands in the range of 1.4–1.6µm. The H2O content and the cloud top altitude have been retrieved for the complete Venus Express dataset from 2006 to 2014 taking into account multiple scattering in the cloudy atmosphere. The cloud top altitude, corresponding to unit nadir aerosol optical depth at 1.48µm, varies from 68 to 73km at latitudes from 40ºS to 40ºN with an average of 70.2±0.8km assuming the aerosol scale height of 4km. In high northern latitudes, the cloud top decreases to 62–68km. The altitude of formation of water lines ranges from 59 to 66km. The H2O mixing ratio at low latitudes (20ºS-20ºN) is equal to 6.1±1.2ppm with variations from 4 to 11ppm and the effective altitude of 61.9±0.5km. Between 30º and 50º of latitude in both hemispheres, a local minimum was observed with a value of 5.4±1ppm corresponding to the effective altitude of 62.1±0.6km and variations from 3 to 8ppm. At high latitudes in both hemispheres, the water content varies from 4 to 12ppm with an average of 7.2±1.4ppm which corresponds to 60.6±0.5km. Observed variations of water vapor within a factor of 2-3 on the short timescale appreciably exceed individual measurement errors and could be explained as a real variation of the mixing ratio or/and possible variations of the cloud opacity within the clouds. The maximum of water at lower latitudes supports a possible convection and injection of water from lower atmospheric layers. The vertical gradient of water vapor inside the clouds explains well the increase of water near the poles correlating with the decrease of the cloud top altitude and the H2O effective altitude. On the contrary, the depletion of water in middle latitudes does not correlate with the H2O effective altitude and cannot be completely explained by the vertical gradient of water vapor within the clouds. Retrieved H2O mixing ratio is higher than those obtained in 2.56µm from VIRTIS-H data (Cottini et al., 2015 Planet. Space Sci., 113, 219–225 ) at altitudes of 68–70km which is well consistent with the lower altitudes of water mixing ratio from the 1.38µm band. Observations for different solar and emission angles allowed to constrain also the average vertical distribution of H2O mixing ratio in the clouds with 2ppm at 66km and 7–7.5ppm at 59–61km. The water vapor latitudinal-longitudinal distribution does not show any direct correlation with the cloud tops. Yet a strong asymmetry of H2O longitudinal distribution has been observed with a maximum of 7–7.5ppm from −120º to 30º of longitude and shifted to the southern hemisphere (20ºS-10ºN). To the east, the minimum is observed with values not in excess of 6ppm and over a wide range of longitudes from 30º to 160º. Bertaux et al. (2015) announced a correlation between the zonal wind pattern in the equatorial region and underlying topography of Aphrodite Terra as the result of stationary gravity waves produced at the ground level near the mountains. The water minimum corresponds to the Aphrodite Terra highlands and can be also associated with the influence of Venus topography. No prominent long-term on the time scale of 8.5 years nor local time variations of water vapor and the cloud top altitude were detected.
Hydrogen chloride was discovered in the atmosphere of Mars for the first time during the global dust storm in Mars year (MY) 34 (July 2018) using the Atmospheric Chemistry Suite mid-infrared channel ...(ACS MIR) on the ExoMars Trace Gas Orbiter. The simultaneity of variations in dust and HCl, and a correlation between water vapour and HCl, led to the proposal of a novel surface-atmosphere coupling analogous to terrestrial HCl production in the troposphere from salt aerosols. After seasonal dust activity restarted in MY 35 (August 2020), we have been monitoring HCl activity to determine whether such a coupling was validated. Here we present a new technique for analysing the absorption features of trace gases close to the ACS MIR noise level and report that HCl mixing ratios are observed to rapidly increase in both hemispheres coincidentally with the onset of the MY 35 perihelion dust season. We present the temporal evolution of the vertical distribution of HCl (0.1–6 ppbv) and of dust activity in both hemispheres. We also report two observations of >2 ppbv HCl below 10 km in the northern hemisphere during the aphelion period.
•Venus’ upper haze was observed at 70–95km by SPICAV IR.•Detached haze layers were detected at altitudes from 70 to 90km.•The aerosol scale height equals to 3.3±0.7km.•Particle size and number ...density profiles for bimodal and unimodal cases are retrieved.•Unimodal radius equals 0.54±0.25μm and is smaller in the polar region than in nonpolar regions.
SPICAV IR, a channel of the SPICAV/SOIR suite of instruments onboard Venus Express spacecraft measured spectra in nadir and solar occultation modes in the range of 0.65–1.7μm. We report results from 222 solar occultations observed from May 2006 to November 2014. The vertical resolution of measurements varies from 1 to 25km depending on the distance of the spacecraft to the limb of Venus. The vertical profiles of atmospheric extinction were obtained at 10 near-IR wavelengths in the altitude range from 70 to 95km. This allowed us to derive microphysical properties of the mesospheric haze. The aerosol haze top is higher near the equator than near the pole. In the upper haze, the aerosol scale height is found to be 3.3±0.7km. Detached haze layers were detected at altitudes from 70 to 90km. Particle size and number density profiles are retrieved from extinction coefficients using Mie scattering theory adopting H2SO4 refractive indices. Bimodal distribution of particles is consistent with data for some orbits with mean radius for mode 1 reff1=0.12±0.03μm and reff2=0.84±0.16μm for mode 2. Particle radii tend to cluster within occultation campaign and vary on the time scale of several months. The radius for the single mode case equals Reff=0.54±0.25μm, and they are also 1.5–2 times smaller in the polar region (60°N–90°N) than in nonpolar regions (60°S–60°N). In bimodal case the number density profiles decrease smoothly for both modes, from ∼500cm−3 at 75km to ∼50cm−3 at 90km for mode 1, and from ∼1cm−3 at 75km to ∼0.1cm−3 at 90km for mode 2.
The properties of Martian aerosols are an integral part of the planetary climatology. Global dust storms (GDS) significantly alter spatial and vertical distributions of dust and water ice aerosols ...and their microphysical properties. We explored the 2018/Martian year 34 GDS with the Atmospheric Chemistry Suite instrument onboard the ESA‐Roscosmos Trace Gas Orbiter mission. Solar occultation observations of thermal infrared and near infrared channels in the 0.7–6 μm spectral range with >103 signal‐to‐noise ratio are used to constrain the vertical dependence and the temporal evolution of the particle properties of water ice and dust (effective radius, effective variance, number density, and mass loading) before the 2018 GDS and during its onset and decay phases. In most of the observations, the particle size of dust and water ice decreases with altitude. The effective radius of dust and water ice particles ranges in 0.1−3.5 μm and 0.1–5.5 μm, respectively. The largest aerosol particles (> 2.5 μm for dust and > 3.5 μm for water ice) are present below 10 km before the onset and during the GDS decay phase. During the peak of the GDS, dust reached altitudes of 85 km; the most frequently observed effective radius is 1–2 μm with 0.1–1 cm−3 number density and 0.1 effective variance. Detached layers of water ice composed of 0.1–1 μm particles are systematically observed at 50–100 km during this period. Below, at 0–50 km, we see the dust mixed with the main water ice layer comprising 1–4 μm particles.
Plain Language Summary
Suspended in the air, mineral dust and water ice particles play a key role in thermal balance and circulation of the atmosphere of Mars and its climate. In that context, global dust storms are rare but powerful events that significantly alter spatial and vertical distributions of dust and water ice particles and their properties. The most recent event, which occurred in the summer of 2018, was monitored by the Atmospheric Chemistry Suite instrument onboard the ESA‐Roscosmos Trace Gas Orbiter mission. Solar occultation observations carried out in the visible and the middle infrared spectral ranges enabled monitoring of dust and water ice particles properties such as size, number of particles and their mass per unit volume, and the width of their size distribution during the evolution of the storm. Dust was lifted to 85 km, while water ice clouds were observed at even higher altitudes, up to 100 km.
Key Points
Atmospheric Chemistry Suite solar occultations in the 0.7–6 μm spectral range separate microphysical properties of dust and water ice aerosols in Martian atmosphere
The observed particle radius ranges from 0.1 to 3.5 μm for dust and from 0.1 to 5.5 μm for water ice clouds, with the largest particles found below 10 km
Water ice clouds with 0.1–1 μm particles reached altitudes up to 100 km during the peak of the 2018 global dust storm
The Thermal InfraRed channel in honor of professor Vassili Ivanovich Moroz (TIRVIM) of the Atmospheric Chemistry Suite onboard ExoMars Trace Gas Orbiter has continuously monitored the Martian ...atmosphere from 13 March 2018 until 2 December 2019, covering almost a complete Martian Year (MY). In the nadir mode of observations, infrared spectra obtained by TIRVIM in the spectral range 600–1,300 cm−1 permit retrievals of vertical temperature profiles from the surface up to 60 km of altitude, surface temperatures and column aerosol optical depths. Here we report the retrieved atmospheric thermal structure and the column dust content during the global dust storm (GDS) of MY 34 monitored from Ls = 182.2° to Ls = 211.8° (Solar Longitude), capturing the evolution of the GDS and the response of the atmospheric thermal structure to the changing dust loading. The global storm caused asymmetric atmosphere heating, predominantly in the southern hemisphere, and changed diurnal contrast of atmospheric thermal structure. We also observe a reduced diurnal contrast of surface temperatures at the peak of the GDS.
Plain Language Summary
The thermal radiation emitted by Mars in the spectral range 7.7–16.7 μm was measured by the Atmospheric Chemistry Suite Thermal InfraRed channel in honor of professor Vassili Ivanovich Moroz (ACS TIRVIM) onboard ExoMars Trace Gas Orbiter. The nadir spectra carry information about the temperature of the atmosphere at different altitudes thanks to a deep CO2 absorption present around 15 μm. Also, the dust loading can be found from the 9‐μm silicate absorption, and the surface temperature can be estimated at 7 μm where the atmosphere is mostly transparent. We follow the evolution of these parameters during the strong global dust storm of Martian Year (MY) 34 (2018). The peculiarity of the ACS TIRVIM data set is the exceptionally dense coverage providing a new look at this otherwise well‐studied dust event.
Key Points
Atmospheric thermal structure and dust content on Mars are retrieved from Atmospheric Chemistry Suite Thermal InfraRed channel nadir measurements in the spectral range 7.7–16.7 μm
The 2018 global dust storm covered the entire planet and caused an asymmetric heating of the atmosphere with a hotter southern hemisphere
We observe a reduced diurnal contrast of surface temperatures and a changed contrast of atmospheric thermal structure during the storm
Our research aimed to study the ability of ixodid ticks to accumulate heavy metals in their bodies within a large industrial city. We used 2128 units of adult hungry ixodid ticks and 10 units of ...vegetation samples, collected from March 2018 to September 2020 in Zaporizhzhia (large industrial city, southeastern Ukraine). The samples were examined for the content of Cd, Pb, and Ca by the spectrometer with inductively coupled plasma series ICP-OES (Shimadzu). We also used the method of determining the locomotor activity for ticks’ behavior study. Our results demonstrated that the concentration of toxic elements in the ticks enlarges along with the content of these elements in the ground litter (r = 0.98). Analyzed the calcium content in the body of ixodid ticks, we clustered them in two groups according to the element susceptibility. Two–way analysis of variances regards cadmium and calcium accumulation in the body of Ixodid ticks proved the dependence of calcium content in ticks on the habitat degree of cadmium accumulation (P = 44.90, 0.0001, ANOVA). We suggested that the high industrialization level of industrial cities directly affect the ecology of Ixodid ticks, which, in turn, could cause the susceptibility of ticks to the pathogens.
Spectroscopic solar occultation measurements by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus/Solar Occultation at Infrared instrument (SPICAV/SOIR) onboard the ...Venus Express orbiter gave new data about upper haze aerosol properties, its vertical distribution and spatial and temporal variations. Early study with three channels of SPICAV/SOIR instrument using a few selected orbits indicated presence of two aerosol modes in particle size distribution (Wilquet et al., 2009). Analysis of aerosol properties from the SPICAV−IR spectrometer for the whole Venus Express data set obtained from May 2006 till November 2014 has proved it for some occultations (Luginin et al., 2016). In this work, we report retrieval of the upper haze (81–100 km) aerosol properties from 101 simultaneous SPICAV−UV and –IR solar occultation sessions acquired between March 2007 and January 2013. A joint analysis of the data from two spectrometers allowed us to characterize the size distribution ~10 km higher in the atmosphere compared to previous analysis and to detect bimodal distribution in ~50% of observations previously believed to be unimodal. At altitudes 81–92 km bimodality is observed in >50% of cases. Mode 2 particles are detected up to 98 km and mode 1 up to 100 km. Mean radius equals 0.14 ± 0.03 μm for mode 1 and 0.78 ± 0.18 μm for mode 2. Number density profiles for both modes of particles exponentially decrease with altitude, starting from 50 cm−3 and 0.3 cm−3 at 82 km for mode 1 and mode 2, respectively, and reaching 3 cm−3 at 98 km for mode 1 and 0.03 cm−3 at 94 km for mode 2.
•Solar and stellar occultation data were processed from UV spectrometry on Venus.•Vertical profiles of SO2 content were retrieved between 85 and 100km of altitude for the 2006–2014 period.•The SO2 ...mixing ratio tends to increase with altitude.•The night time distribution of SO2 content was retrieved for the first time in the Venus upper mesosphere.
In this paper we present the first night side distribution of SO2 content in Venus’ upper mesosphere (altitudes from 85 to 105km). The dataset is based on the SPICAV UV stellar occultation experiment which took place onboard ESA's Venus Express (VEX) orbiter in 2006–2014. The UV channel of SPICAV spectrometer detected absorption bands of SO2 and CO2 in the spectral range 180–300nm with a resolution of 1–2nm while stellar light was occulted by the mesosphere. Altitude profiles of sulfur dioxide's volume mixing ratio (VMR) could be retrieved in the upper part of the mesosphere covering the whole night side on Venus. In parallel, we have reprocessed the terminator UV solar occultations dataset (Belyaev et al., 2012. Icarus 217, 740–751) in the same altitude range and extended its statistics until 2014. On average the SO2 VMR increases with altitude from 10–30 ppb at 85km to 100–300 ppb at 100km in both regimes of occultation. The midnight SO2 abundance appears to be 3–4 times higher than in the terminator region: 150–200ppbv versus 50pppv at altitude around 95km. These new results were compared with the distribution of oxygen atoms, which are tracers of the global subsolar-antisolar (SS-AS) circulation at ∼100km (the data provided by Soret et al., 2012 Icarus, 217, 849–855). The night time behavior looks similar for SO2 molecules and O atoms with a correlation coefficient Rcorr= 0.73. Moreover, the retrieved SO2 enrichment above 85km appears to correlate with the density of H2SO4 droplets (Luginin et al., 2016; Icarus 277, 154–170).
The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared ...spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm
−1
. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described.
•Aerosol scale heights are equal to 4 − 5.5 km at 82N-90 N and 2 − 4 km at 60N − 80 N latitudes.•Detached layers in upper haze are observed at 80 − 88 km at morning, and at 84 − 90 km at ...evening.•Proposed explanation: detached layers are formed by condensation of water vapor on droplets of sulfuric acid.•Vertical optical depth of detached layers at 1.1 μm varies in (0.8 − 3)•10−3 range.
SPICAV IR, one channel of SPICAV/SOIR instrument suite onboard Venus Express, performed solar occultation measurements of the atmosphere at terminators in 0.65–1.7 µm spectral range. We analyze the properties of the upper part of the Venus aerosol layer (upper haze, 70 − 95 km altitude) from 798 observations performed from May 2006 through November 2014. Vertical profiles of slant optical depth, extinction coefficient, effective radius, and number density of haze particles from 222 orbits were analyzed in a previous publication (Luginin et al., 2016); their diurnal, latitudinal, and interannual variabilities were investigated. The present paper is devoted to analysis of scale heights and properties of detached haze layers from 147 orbits at mid-to-high northern latitudes, where the best spatial resolution was obtained. Scale heights retrieved from 43 orbits were equal to 4 − 5.5 km at the North Pole (82°N-90°N) decreasing to 2 − 4 km at 60°N − 80°N latitudes. As an explanation of such latitudinal variations, we propose a mechanism based on vertical transport driven by winds that are directed upward at the North Pole and downward at 60°N − 80°N latitudes. Detached layers were detected in 93 occultations at 58°N − 90°N. The detached layers are presumably formed through condensation of water vapor on droplets of sulfuric acid water solution; they were mostly seen at 80 − 88 km at the morning terminator, and at 84 − 90 km at the evening one. This difference in altitude of the detached layers can be explained by diurnal variations in thermal structure of Venusian mesosphere. The vertical optical depth of detached layers varies broadly around the mean τDL ∼ 0.8 − 3·10−3; no difference between the morning and the evening terminators was observed. The effective radius and number density of aerosol particles in the detached layers group around a very wide maximum at the morning terminator (0.65 ± 0.25 µm and 0.6 ± 0.4 cm−3) and two maxima at the evening terminator (0.4 ± 0.1 µm and 0.85 ± 0.15 µm; 0.3 ± 0.2 cm−3 and 4.5 ± 2.5 cm−3). This could be explained by differences in initial altitudes at which condensation of particles occurs.
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