CO Profiles Research Articles

Atmospheric CO2 inversion reveals the Amazon as a minor carbon source caused by fire emissions, with forest uptake offsetting about half of these emissions

Abstract. Tropical forests such as the Amazonian rainforests play an important role for climate, are large carbon stores and are a treasure of biodiversity. Amazonian forests have been exposed to large-scale deforestation and degradation for many decades. Deforestation declined between 2005 and 2012 but more recently has again increased with similar rates as in 2007–2008. The resulting forest fragments are exposed to substantially elevated temperatures in an already warming world. These temperature and land cover changes are expected to affect the forests, and an important diagnostic of their health and sensitivity to climate variation is their carbon balance. In a recent study based on CO2 atmospheric vertical profile observations between 2010 and 2018, and an air column budgeting technique used to estimate fluxes, we reported the Amazon region as a carbon source to the atmosphere, mainly due to fire emissions. Instead of an air column budgeting technique, we use an inverse of the global atmospheric transport model, TOMCAT, to assimilate CO2 observations from Amazon vertical profiles and global flask measurements. We thus estimate inter- and intra-annual variability in the carbon fluxes, trends over time and controls for the period of 2010–2018. This is the longest period covered by a Bayesian inversion of these atmospheric CO2 profile observations to date. Our analyses indicate that the Amazon is a small net source of carbon to the atmosphere (mean 2010–2018 = 0.13 ± 0.17 Pg C yr−1, where 0.17 is the 1σ uncertainty), with the majority of the emissions coming from the eastern region (77 % of total Amazon emissions). Fire is the primary driver of the Amazonian source (0.26 ± 0.13 Pg C yr−1), while forest carbon uptake removes around half of the fire emissions to the atmosphere (−0.13 ± 0.20 Pg C yr−1). The largest net carbon sink was observed in the western-central Amazon region (72 % of the fire emissions). We find larger carbon emissions during the extreme drought years (such as 2010, 2015 and 2016), correlated with increases in temperature, cumulative water deficit and burned area. Despite the increase in total carbon emissions during drought years, we do not observe a significant trend over time in our carbon total, fire and net biome exchange estimates between 2010 and 2018. Our analysis thus cannot provide clear evidence for a weakening of the carbon uptake by Amazonian tropical forests.

Emission study on a direct injection diesel engine powered with blends of Moringa oleifera biodiesel‐diesel

AbstractThe current investigation uses biodiesel extracted from Moringa oleifera seeds in a diesel engine. M. oleifera biodiesel is prepared via conventional transesterification with standard conditions (60°C reaction temperature, 120 min reaction time, 1% by wt. catalyst, and 7.5:1 molar ratio). The test engine is a single‐cylinder air‐cooled naturally aspirated direct injection diesel engine. The test engine for experimentation is operated at 100% load with different engine speeds ranging from 1000 to 2400 rpm. Emissions characteristics were analyzed at different engine speeds. Results were interesting as the MB10 blend (10% M. oleifera biodiesel + 90% diesel) lowered the smoke by 24% and hydrocarbon by 10.34% with respect to neat diesel. Almost all the test fuels have higher HC profiles at reduced engine speeds. The MB20 blend lowered the CO profile to the CO profile of diesel fuel by about 0.84%. However, it can be observed that the MB10 blend's average CO profile is improved by 1.97% than mineral diesel. These results are compromised with higher CO and NOx profiles of 2.4% and 8.9%, respectively.

Satellite-based estimates of high-resolution CO concentrations at ground level in the Yangtze River Economic Belt of China

This study proposed a method to downscale ground-level CO concentrations from satellite observations. Taking the Yangtze River Economic Belt of China as the study area, ground-level CO concentrations (0.25° × 0.25°) were first estimated from the troposphere (MOPITT) CO columns and atmospheric CO profiles simulated by the chemical transport model CAM-CHEM; then the resulting data was downscaled to 1 × 1 km2 based on an algorithm of multiscale geo-weighted regression (MGWR) model with the auxiliary factors. The estimated ground-level CO concentrations were in good agreement with the observations at ground-based sites (RMSE = 0.25 mg/m3, PRE = 19%). In the Yangtze River Economic Belt, monthly ground-level CO concentrations showed obvious temporal and spatial variations, ranging from 0.30 to 0.81 mg/m3 and an average of 0.49 mg/m3; high CO values occurred in winter, while low in summer; hotspots of CO concentrations were concentrated in the northern Yangtze River Delta and the urban areas.

Influence of hot-air and infra-red pretreatments on oxidative stability, physicochemical properties, phenolic and fatty acid profile of white and black chia seed (Salvia hispanica L.) oil

In this research, the effect of hot-air (HAP) and infra-red (IRP) pretreatments at 160 and 180˚C for the time duration of 5, 10, and 15 min on the physicochemical characteristics, phenolic composition, and stability attributes of white (WCO) and black chia seed oil (BCO) were investigated. The WCO and BCO exhibited comparable physicochemical and stability characteristics while the level of phenolic compounds was higher in BCO. The phenolic acids, flavonoids, pigments, oxidative stability, Maillard reaction products, browning index, ΔE and a* value increased significantly while L*, b*, chroma and hue values decreased significantly at higher HAP and IRP exposure duration and temperature. The hydroxybenzoic (protocatechuic, vanillic, and syringic acid), hydroxycinnamic (p-coumaric, chlorogenic, sinapic, and rosmarinic acids) acids and flavonoids (epicatechin, vitexin, rutin, myricetin, luteolin, and apigenin) were highest in oil after HAP at 180°C for 15 min. The infra-red spectral information relates to oxidation and fatty acid composition of pretreated CO. HAP is more effective than IRP for improving oil yield, oxidative stability, and phenolic profile of CO.

The SOIR/Venus Express species concentration and temperature database: CO2, CO, H2O, HDO, H35Cl, H37Cl, HF individual and mean profiles

This work is an update of the SOIR mean and individual profiles of CO2, CO, H2O, HDO, H35Cl, H37Cl, HF, and the temperature measured at the Venus terminator during the Venus Express mission (2006–2014).The previous versions of the database were published by Chamberlain et al. (2020); Mahieux et al. (2015a); Mahieux et al. (2012); Mahieux et al. (2015c); Vandaele et al. (2016a, b). Updates to the pipeline to computing the calibrated transmittances by Trompet et al. (2016) and to the retrieval code led to a new database version.For each species, we provide the individual profiles and associated uncertainties. We compute the mean profiles and their associated variability of the whole database, the morning and evening profiles for absolute latitudes lower than 60°, and for four latitude bins (0°-30°, 30°-60°, 60°-80°, and 80°-90°) assuming equatorial and side of the terminator symmetry. The mean profiles are compared to the ones of the previously published database and with literature profiles. They are all in good agreement.The numerical values of the mean profiles are provided in the Appendix of this work, the individual profiles are available on the VESPA platform, and the calibrated transmittances are available on the ESA PSA.

Construction of the Global Reference Atmospheric Profile Database

Atmospheric profiles are important input parameters for atmospheric radiative transfer models and atmospheric parameter inversions. The construction of regionally representative reference atmospheric profiles can provide basic data for global atmospheric and environmental research. Most reference atmospheric profile databases commonly used lag behind in updating frequency. These databases usually have limited spatial and temporal resolution and differ greatly from the real atmospheric state. To present the real atmospheric state, this article constructs the Global Reference Atmospheric Profile Database (GRAP) based on ACE-FTS satellite products of 2021 and 2022, AIRS satellite products and ERA5 reanalysis data of 2022 u6sing a random forest regression model and a hierarchical mean algorithm. The radiance spectrum of FY-3E HIRAS-II using different profile databases was simulated and compared with the measured spectrum. The results show that GRAP spectral simulations fit better with the measured HIRAS-II spectrum. Comparing the CO2, CH4, O3 and N2O profiles of GRAP, AFGL, MIPAS, RTTOV and NDACC ground station profiles in equatorial, mid-latitude summer and polar winter, the results show that GRAP has high spatial and temporal resolution and better fits the current real atmospheric state. Comparing the temperature profiles of eight regions in China, the results illustrate that GRAP is a better representation of the state of the atmosphere in the Chinese region. GRAP can provide fundamental atmospheric data for radiative transfer studies and atmospheric parameter inversions.

Are We Recording? Putting Embayment Speedometry to the Test Using High Pressure‐Temperature Decompression Experiments

AbstractDespite its increasing application to estimate magma decompression rates for explosive eruptions, the embayment speedometer has long awaited critical experimental evaluation. We present the first experimental results on the fidelity of natural quartz‐hosted embayments in rhyolitic systems as recorders of magma decompression. We conducted two high pressure‐temperature isobaric equilibrium experiments and 13 constant‐rate, continuous isothermal decompression experiments in a cold‐seal pressure vessel where we imposed rates from 0.005 to 0.05 MPa s−1 in both H2O‐saturated and mixed‐volatile (H2O + CO2)‐saturated systems. In both equilibrium experiments, we successfully re‐equilibrated embayment melt to new fluid compositions at 780°C and 150 MPa, confirming the ability of embayments to respond to and record changing environmental conditions. Of the 32 glassy embayments recovered, seven met the criteria previously established for successful geospeedometry and were thus analyzed for their volatile (H2O ± CO2) concentrations, with each producing a good model fit and recovering close to the imposed decompression rate. In one H2O‐saturated experiment, modeling H2O concentration gradients in embayments from three separate crystals resulted in best‐fit decompression rates ranging from 0.012 to 0.021 MPa s−1, in close agreement with the imposed rate (0.015 MPa s−1) and attesting to the reproducibility of the technique. For mixed‐volatile experiments, we found that a slightly variable starting fluid composition (2.4–3.5 wt.% H2O at 150 MPa) resulted in good fits to both H2O + CO2 profiles. Overall our experiments provide confidence that the embayment is a robust recorder of constant‐rate, continuous decompression, with the model successfully extracting experimental conditions from profiles representing nearly an order of magnitude variation (0.008–0.05 MPa s−1) in decompression rate.

Shea Butter Oil Biodiesel Synthesized Using Snail Shell Heterogeneous Catalyst: Performance and Environmental Impact Analysis in Diesel Engine Applications

The implementation of biodiesel in internal combustion engines has been observed to enhance engine performance and mitigate the discharge of toxic gaseous emissions from the engine. In this research, Shea Butter Oil Biodiesel (SBOB) was used to operate a diesel engine to analyze the performance and emissions characteristics. Shea Butter Oil Biodiesel (SBOB) was blended with petroleum diesel in ratios 0:100 (B0), 25:75 (B25), 50:50 (B50), 75:25 (B75), and 100:0 (B100). The torque, brake power (BP), and brake thermal efficiency (BTE) of the engine were determined. Gaseous emissions from the engine’s combustion were characterized using the BOSEAN BH-4S portable multi-gas detector, while the organic emissions compositions were detected and quantified using Gas Chromatography-Mass Spectrometry (GC-MS). The fuel properties of SBOB and its blends were found to be within the range of acceptable standards. However, the carbon content, sulphur content, heating value, and ash content of the blends decreased from 0.68 to 0.12 wt %, 0.04 to 0.00 wt %, 44.2 to 34.2 MJ/kg, and 0.020 to 0.010 wt %, respectively. The engine torque, brake power, BTE, and engine vibrations were found to reduce when the biodiesel blends were used. Besides the diesel fuel, the biodiesel blend, B25, produced the best engine performance characteristics with 8.50 Nm torque, 1780.95 W BP, and 90.29% BTE. The B100 produced the lowest concentrations of carbon emissions, viz. 520 ppm CO and 1.0% CO2. The NO and NO2 concentrations were found to increase for all the biodiesel blends used. The NO and NO2 concentrations were measured as 230 ppm and 210 ppm for B0, respectively, and 250 ppm and 235 ppm for B25, respectively. The research showed that SBOB has improved engine performance and lowered the emissions profile of CO and CO2 compared with petroleum diesel. The GCMS analysis confirmed that some harmful organic compounds were present in the emissions profile obtained from the exhaust samples of the diesel engine at various compositions.

Computational Fluid Dynamics Analysis of a Hollow Fiber Membrane Module for Binary Gas Mixture

The membrane gas separation process has gained significant attention using the computational fluid dynamics (CFD) technique. This study considered the CFD method to find gas concentration profiles in a hollow fiber membrane (HFM) module to separate the binary gas mixture. The membrane was considered with a fiber thickness where each component’s mass fluxes could be obtained based on the local partial pressures, solubility, diffusion, and the membrane’s selectivity. COMSOL Multiphysics was used to solve the numerical solution at corresponding operating conditions and results were compared to experimental data. The two different mixtures, CO2/CH4 and N2/O2, were investigated to obtain concentration gradient and mass flux profiles of CO2 and O2 species in an axial direction. This study allows assessing the feed pressure’s impact on the HFM system’s overall performance. These results demonstrate that the increment in feed pressures decreased the membrane system’s separation performance. The impact of hollow fiber length indicates that increasing the active fiber length has a higher effective mass transfer region but dilutes the permeate-side purities of O2 (46% to 28%) and CO2 (93% to 73%). The results show that increasing inlet pressure and a higher concentration gradient resulted in higher flux through the membrane.

Synergistic effect of cobalt and cerium on the structural properties and biological behavior of sol-gel-derived mesoporous bioactive glass nanoparticles

Chronic wounds are challenging to treat due to their complex interactions with the skin and underlying tissues. Bioactive glass (BG) has shown promise in treating these wounds, but more research is needed to fully understand its potential. In this study, spherical mesoporous BG nanoparticles were prepared by the sol-gel process, with Ce and Co incorporated into the glass matrix by a post-modification procedure. The release profile of Si, Ce, and Co was monitored over 14 days using simulated exudate fluid (SEF), which has not been previously reported in the literature. The structural properties and biological behavior were evaluated using various techniques, which showed that Ce and Co had a synergistic effect on BG, resulting in samples with high cell viability and antibacterial activity. This study may contribute to the further development of biomaterials for skin wound healing.

Impact of short- and long-term exposure to air pollution on lipid profile in adults aged 20 to 69 years in Tehran Province, Iran

There are inconsistent findings concerning the impact of air pollution on different lipid measures and there is a lack of data for the highly polluted Middle East and North Africa (MENA) region. To assess the association between short-term exposure to five major air pollutants including PM10, NO2, SO2, O3, and CO, and lipid profiles as well as long-term exposure to these pollutants and incident dyslipidemia. A total of 5,821 participants (3,387 women) aged 20–69 years at baseline were followed from 2001 to 2018, every three years. The mixed-effects model evaluated the impact of air pollutants on blood lipids including TC, TG, HDL-C, LDL-C, and non-HDL-C. The proportional hazards Weibull model estimated the long-term impacts of air pollutants on incident dyslipidemia. Applying the Bonferroni correction, the significance level of 0.0014 (0.05/35) and 0.0033 (0.05/15) was set for short- and long-term scenarios, respectively. In the short term, SO2 and CO had consistent unfavorable effects on lipid profiles, including TC, TG, LDL-C, non-HDL-C, and HDL-C (only for CO). Moreover, short-term exposure to O3 and NO2 had negative associations with TG, LDL-C, HDL-C, and TC (only NO2) and positive associations with HDL-C. Generally, in a long-term manner, CO was associated with a higher incidence of high TC, high TG, and low HDL-C; NO2 and O3 were associated with a lower incidence of high TG and low HDL-C; 1- and 2-year exposure to PM10 was associated with lower incidence of low HDL-C and 3-year exposure to PM10 was associated with lower high TC and high non-HDL-C. In conclusion, given the robust unfavorable impact of CO on lipid profiles in both short- and long-term periods, more interventions should be conducted to reduce the impact of CO exposure.

Molecular insights into the dissociation of carbon dioxide hydrates in the presence of an ionic liquid, [BMIM][PF6

Methane production from hydrate reservoirs using combined CO2and chemical inhibitor injection is a potential method for simultaneous methane recovery and CO2sequestration. Molecular dynamics simulations have been performed to study the dissociation of CO2hydrates in the presence and absence of the ionic liquid, viz., [BMIM][PF6], at 250, 255 and 260 K and pressures ranging from 20 to 60 bar. Effect of [BMIM][PF6] on hydrate thickness has been demonstrated to be not significant by hydrogen bonding and order parameter analyses. Local number density profiles of guest and host molecules show that in presence of this ionic liquid, deviation from hydrate-like behaviour is less than in its absence. This is due to preferential association of CO2with [PF6]- anion. The asymmetry in the density profiles of CO2 and H2O brings out the role of filled and empty partial cages at the interfaces on hydrate dissociation in the presence of [BMIM][PF6].

Cover Feature: Polypyridyl CoII‐Curcumin Complexes as Photoactivated Anticancer and Antibacterial Agents (ChemBioChem 10/2023)

Visible light-induced anticancer and antibacterial profiles of Co(II) curcumin complexes. This cover illustrates Co(II)-curcumin conjugates exhibiting remarkable visible light-triggered anticancer activity against breast cancer (MCF-7) cells by ROS-induced apoptosis and the fluorescent nature of curcumin assisting in cell imaging. Also, antibacterial activity against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacterial strains through the activation of the Co(II)-curcumin conjugates at the targeted site by light exposure, is depicted here. More information can be found in the Research Article by B. Koch, S. Banerjee.

Differences in MOPITT surface level CO retrievals and trends from Level 2 and Level 3 products in coastal grid boxes

Abstract. Users of MOPITT (Measurement of Pollution in the Troposphere) data are advised to discard retrievals performed over water from analyses. This is because MOPITT retrievals are more sensitive to near-surface CO when performed over land than water, meaning that they have a greater measurement component and are less tied to the a priori CO concentrations (which are taken from a model climatology) that are necessarily used in their retrieval. MOPITT Level 3 (L3) products are a 1∘ × 1∘ gridded average of finer-resolution (∼ 22 × 22 km) Level 2 (L2) retrievals. In the case of coastal L3 grid boxes, L2 retrievals performed over both land and water may be averaged together to create the L3 product, with L2 retrievals over land not contributing to the average at all in certain situations. This conflicts with data usage recommendations. The aim of this paper is to highlight the consequences that this has on surface level retrievals and their temporal trends in “as-downloaded” L3 data (L3O), by comparing them to those obtained if only the L2 retrievals performed over land are averaged to create the L3 product (L3L), for all identified coastal L3 MOPITT grid boxes. First, the difference between surface level retrievals in L3L and the corresponding L2 retrievals performed over water (L3W) is established for days when they are averaged together to create the L3O product for coastal grid boxes (yielding an L3O surface index of “mixed”, L3OM). Mean retrieved volume mixing ratios (VMRs) in L3L differ by over 10 ppbv from those in L3W, and temporal trends detected in L3L are between 0.28 and 0.43 ppbv yr−1 stronger than in L3W, on average. These L3L − L3W differences are clearly linked to retrieval sensitivity differences, with L3W being more heavily tied to the a priori CO profiles used in the retrieval, which are a model-derived monthly mean climatology that, by definition, has no trend year to year. VMRs in the resulting L3OM are significantly different to L3L for 45 % of all coastal grid boxes, corresponding to 75 % of grid boxes where the L3L − L3W difference is also significant. Just under half of the grid boxes that featured a significant L3L − L3W trend difference also see trends differing significantly between L3L and L3OM. Factors that determine whether L3OM and L3L differ significantly include the proportion of the surface covered by land/water and the magnitude of land–water contrast in retrieval sensitivity. Comparing the full L3O dataset to L3L, it is shown that if L3O is filtered so that only retrievals over land (L3OL) are analysed – as recommended – there is a huge loss of days with data for coastal grid boxes. This is because L2 retrievals over land are routinely discarded during the L3O creation process for these grid boxes. There is less data loss if L3OM retrievals are also retained, but the resulting L3O “land or mixed” (L3OLM) subset still has fewer data days than L3L for 61 % of coastal grid boxes. As shown, these additional days with data feature some influence from retrievals made over water, demonstrably affecting mean VMRs and their trends. Coastal L3 grid boxes contain 33 of the 100 largest coastal cities in the world, by population. Focusing on the L3 grid boxes containing these cities, it is shown that mean VMRs in L3OL and L3L differ significantly for 11 of the 27 grid boxes that can be compared (there are no L3OL data for 6 of the grid boxes studied), with 9 of the 18 grid boxes where temporal trend analysis can be performed in L3OL featuring a trend that is significantly different to that in L3L. These differences are a direct result of the data loss in L3OL – data that are available in L2 data (and are incorporated into the L3L product created for this study). The L3L − L3OLM mean VMR difference exceeds 10 (22) ppbv for 11 (3) of these 33 grid boxes, significant in 13 cases, with significant temporal trend differences in 5 cases. It is concluded that an L3 product based only on L2 retrievals over land – the L3L product analysed in this paper, available for public download – could be of benefit to MOPITT data users.

Mobile measurement of vehicle emission factors in a roadway tunnel: A concentration gradient approach

Tunnels are the preferred experimental environments for estimating vehicle emission factors (EFs) under real-world driving conditions. In this study, online measurements of traffic-related air pollutants (including CO2, NOX, SO2, O3, particulate matter [PM], and volatile organic compounds [VOCs]) were conducted using a mobile laboratory in the Sujungsan Tunnel in Busan, Korea. Mobile measurements generated concentration profiles of the target exhaust emissions inside the tunnel. These data were used to produce a zonation of the tunnel, i.e., mixing and accumulation zones. There were differences between the CO2, SO2, and NOX profiles, and a starting point that was free from ambient air mixing effects could be set at 600 m from the tunnel entrance. The EFs of vehicle exhaust emissions were calculated using pollutant concentration gradients. The average EFs for CO2, NO, NO2, SO2, PM10, PM2.5, and ∑VOCs were 149,000, 380, 55, 29.2, 9.64, 4.33, and 16.7 mg km−1·veh−1, respectively. Among the VOC groups, alkanes contributed more than 70% of the VOC EF. Mobile measurement-derived EFs were validated using the conventional EFs from stationary measurements. The EF results from the mobile measurements matched those from the stationary measurements, while the absolute concentration differences between them implied complex aerodynamic movements of the target pollutants inside the tunnel. This study demonstrated the usefulness and advantages of applying mobile measurements in a tunnel environment and indicated the potential of the approach for observation-based policymaking.

Microporous membrane and culture medium affect in vitro seedling development of Dalbergia nigra (Vell.) Ex Benth. (Fabaceae) by modulation of the protein profile and accumulation of ethylene and CO2

Microporous membrane and culture medium affect in vitro seedling development of Dalbergia nigra (Vell.) Ex Benth. (Fabaceae) by modulation of the protein profile and accumulation of ethylene and CO2

Observing System Choice Can Minimize Interference of the Biosphere in Studies of Urban CO2 Emissions

AbstractCities around the world have introduced initiatives to reduce CO2 emissions. Atmospheric observations can provide evaluation and assessment of these initiatives by quantifying emissions, considering local sources and sinks. The relative importance of the urban biosphere, which can act as both a source (respiration) and sink (photosynthesis) of CO2, has previously been suggested to strongly impact urban CO2 measurements, confounding the ability to use observations to study fossil emissions. However, if using an observing framework that measures a local urban background and the direct urban core outflow, for example, along a downwind airborne transect, the biosphere’s role may be minimized. Here, we combine real, airborne observations of CO2 downwind of select cities in the Northeast US with high‐resolution, back‐trajectory modeling and spatially and temporally resolved surface biosphere and fossil fuel fluxes to characterize the relative biosphere importance to urban CO2 profiles. We show the biosphere influence using this urban observing system to be small, averaging only 15% of the local CO2 enhancement annually, <10% outside of summer, and with a maximum influence of 29% in summer when the biosphere drawdown is most pronounced. Furthermore, when considering two biosphere models that differ by >80%, the impact on observed urban CO2 signals is reduced to only 12% on average. Urban observing frameworks that utilize this local background approach—including those via aircraft or satellite observations—can minimize the biosphere's influence and thus help facilitate robust assessments of urban fossil fuel CO2 emissions.

RESTORING THE CO2 CONCENTRATION ON IR–SPECTRA OF THE SOLAR LIGHT TRANSMISSION THROUGH THE ATMOSPHERE BY THE MODIFIED GAUSS–NEWTON METHOD

The inverse problem of reconstructing the vertical profiles of CO2 in the atmo- sphere by IR–spectra of the solar light transmission is investigated. To solve this problem, we propose the two-stage method. On the first stage, we use the modified Tikhonov method. On the second stage, to approximate a solution of the regularized equation, we apply the modified Gauss–Newton method. The convergence theorem is formulated and the numerical results for a few of measured spectra are presented.

Modeling CO Line Profiles in Shocks of W28 and IC 443

Molecular emission arising from the interactions of supernova remnant (SNR) shock waves and molecular clouds provide a tool for studying the dispersion and compression that might kick-start star formation as well as understanding cosmic-ray production. Purely rotational CO emission created by magnetohydrodynamic shock in the SNR–molecular cloud interaction is an effective shock tracer, particularly for slow-moving, continuous shocks into cold inner clumps of the molecular cloud. In this work, we present a new theoretical radiative transfer framework for predicting the line profile of CO with the Paris–Durham 1D shock model. We generated line profile predictions for CO emission produced by slow, magnetized C shocks into gas of density ∼104 cm−3 with shock speeds of 35 and 50 km s−1. The numerical framework to reproduce the CO line profile utilizes the large velocity gradient (LVG) approximation and the omission of optically thick plane-parallel slabs. With this framework, we generated predictions for various CO spectroscopic observations up to J = 16 in SNRs W28 and IC 443, obtained with SOFIA, IRAM-30 m, APEX, and KPNO. We found that CO line profile prediction offers constraints on the shock velocity and pre-shock density independent of the absolute line brightness and requires fewer CO lines than diagnostics using a rotational excitation diagram.

Martian Atmospheric Temperature and Density Profiles During the First Year of NOMAD/TGO Solar Occultation Measurements

AbstractWe present vertical profiles of temperature and density from solar occultation (SO) observations by the “Nadir and Occultation for Mars Discovery” (NOMAD) spectrometer on board the Trace Gas Orbiter during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in‐house pre‐processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth‐tested retrieval scheme to Mars conditions. Both pre‐processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re‐analysis are briefly discussed.