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The Atmospheric Infrared Sounder (AIRS) on EOS/Aqua satellite provides diverse measurements of Methane (CH4) distribution at different pressure levels in the Earth's atmosphere. The focus of this research is to analyze the vertical variations of (CH4) volume mixing ratio (VMR) time-series data at four Standard pressure levels SPL (925, 850, 600, and 300 hPa) in the troposphere above six cities in Iraq from January 2003 to September 2016. The analysis results of monthly average CH4VMR time-series data show a significant increase between 2003 and 2016, especially from 2009 to 2016; the minimum values of CH4 were in 2003 while the maximum values were in 2016. The vertical distribution of CH4 was relatively high in the cities located in the north of Iraq (Sulaymaniyah and Mosul) more than other cities, especially these in western Iraq (Rutba and Najaf). The highest monthly mean of CH4VMR and standard deviation (SD) was in Sulaymaniyah (1871.11±21.92) ppbv at 925 hPa, while the lowest was in Rutba (1812.81±37.3) ppbv at 300 hPa. Mosul has the second-highest mean and SD next to Sulaymaniyah, especially at the lower levels SPL (925 and 850 hPa) of troposphere more than the rest of selected cities. The seasonal variation of monthly CH4VMR, averaged from 2003 to 2016, shows high values between January and August with a peak between August and September and it declines significantly between October and December with a slight increase in November. Long term trend analysis of monthly CH4VMR at each SPL (925, 850, 600, and 300) hPa above the six cities shows positive values with average growth rates for each SPL equal to (2.9 %, 3.1%, 3.6 %, and 3.9%), respectively. These results indicate that satellite measurements were effective in determining the magnitude of increased CH4 over Iraq that may contribute to the global increase of CH4 in the earth’s Atmosphere.

The results of systematic (2003–2017) measurements of the total content and the volume mixing ratio of CO at Novolazarevskaya station with a spectrometer with a resolution of 0.2 cm– 1 are presented. The inverse problem of determining the total CO content, as well as interfering gases (H2O and N2O), was solved using the SFIT4 software package. Data analysis showed that over the measurement period the average total CO content at Novolazarevskaya amounted to (8 ± 2) 1017 molec/cm2, and the average volume mixing ratio amounted to (37 ± 8) ppb. The obtained data are compared with variations in the total content of CO in Arrival-Heights station, with MOPITT satellite data, as well as with surface values of CO concentration at Syova station. The maximum values of CO are observed in September, the minimum — in January–February. For all the considered series, the trends are insignificant, while there are periods of increased CO content (2010). In recent years (2014–2017) there is a tendency towards an increase in the minimum values of CO. For Novolazarevskaya and Arrival-Heights satellite data are characterized by the excess of over ground data, amounting to 19% and 14%, respectively, while there is a seasonal dependence of the deviation with the minimum in December–January. Surface measurements of the total CO content are in fairly good agreement at Novolazarevskaya and Arrival-Heights, and since 2010 the average deviation is 2.4%. The average value of the concentration of CO on Syova 51 ppb is higher than the average volume mixing ratio at Novolazarevskaya. According to the spectral, wavelet and composite analyzes, in all the considered series there are oscillations in the range of 6–45 months with closely coinciding periods and phases.

In this paper, we present the first measurements of the vertical distribution of cyanogen (${{\rm{C}}}_{2}{{\rm{N}}}_{2}$) in Titan's lower atmosphere at different latitudes and seasons, using Cassini's Composite Infrared Spectrometer far-infrared data. We also study the vertical distribution of three other minor species detected in our data: methylacetylene (${{\rm{C}}}_{3}{{\rm{H}}}_{4}$), diacetylene (${{\rm{C}}}_{4}{{\rm{H}}}_{2}$), and ${{\rm{H}}}_{2}{\rm{O}}$, in order to compare them to ${{\rm{C}}}_{2}{{\rm{N}}}_{2}$, but also to get an overview of their seasonal and meridional variations in Titan's lower stratosphere from 85 km to 225 km. We measured an average volume mixing ratio of ${{\rm{C}}}_{2}{{\rm{N}}}_{2}$ of $6.2\pm 0.8\times {10}^{-11}$ at 125 km at the equator, but poles exhibit a strong enrichment in ${{\rm{C}}}_{2}{{\rm{N}}}_{2}$ (up to a factor 100 compared to the equator), greater than what was measured for ${{\rm{C}}}_{3}{{\rm{H}}}_{4}$ or ${{\rm{C}}}_{4}{{\rm{H}}}_{2}$. Measuring ${{\rm{C}}}_{2}{{\rm{N}}}_{2}$ profiles provides constraints on the processes controlling its distribution, such as bombardment by Galactic Cosmic Rays which seem to have a smaller influence on ${{\rm{C}}}_{2}{{\rm{N}}}_{2}$ than predicted by photochemical models.

Tropical water vapour volume mixing ratio (WVMR) data for October 2004–September 2015 obtained from the Microwave Limb Sounder are used to study its long-term variabilities and tendencies in the height region 12.1–0.002 hPa. Above 0.01 hPa, the WVMR shows minimum March–May and September–November (∼0.7–0.8 ppmv) and maximum during June–August. It shows a large interannual variability at 31–64 km. The results from multivariate regression analysis show an increasing trend with maximum value of ∼0.045 ppmv/yr at 1.21–0.41 hPa. It shows a significant negative solar cycle response at mesospheric heights.

Methane (CH4) Volume Mixing Ratio (VMR) at pressure level 925hPa data extracted from Atmospheric Infrared Sounder (AIRS) with spatial resolution of 1°× 1° covering whole of Iraq and surrounding regions (28.5°–38.5°N, 37.5°–49.5°E) have been examined for the period from January 2003 to December 2013. The results show a considerable increasing of CH4 with maximum values at north and north eastern regions during autumn and the early winter, whereas the minimum values appeared at the pristine desert environment at the west and the south-west region during spring months. For more accuracy validation the trend analysis was applied on the retrieved AIRS data at three different stations are Mosul, Baghdad and Basrah. The mean and standard deviation in Mosul, Baghdad and Basrah was (1.8657 ± 0.0198, 1.8536 ± 0.0196, 1.8448 ± 0.0212) ppmv respectively for monthly long term trend analysis. Monthly trend analyses have positive trends (0.0040, 0.0039 and 0.0042) ppmv.y-1 for Mosul, Baghdad and Basrah Consecutively. These results indicate that Satellite observations efficiently present the temporal and spatial variations of the CH4 for the considered study Area.

During the first perijove passage of the Juno mission, the Jovian InfraRed Auroral Mapper (JIRAM) observed a line of closely spaced oval features in Jupiter's southern hemisphere, between 30°S and 45°S. In this work, we focused on the longitudinal region covering the three ovals having higher contrast at 5 μm, i.e., between 120°W and 60°W in System III coordinates. We used the JIRAM's full spectral capability in the range 2.4–3 μm together with a Bayesian data inversion approach to retrieve maps of column densities and altitudes for an NH3 cloud and an N2H4 haze. The deep (under the saturation level) volume mixing ratio and the relative humidity for gaseous ammonia were also retrieved. Our results suggest different vortex activity for the three ovals. Updraft and downdraft together with considerations about the ammonia condensation could explain our maps providing evidences of cyclonic and anticyclonic structures.

The rotational spectrum of propionitrile (ethyl cyanide, C2H5CN) in the two lowest excited vibrational states, v 13 = 1 and v 21 = 1 , was studied in detail. The compiled experimental data set consisted of published line lists, lines measured from published spectra up to 645 GHz, and new measurements at frequencies from 8 to 331 GHz. The two states are subject to considerable mutual interaction but application of a- and b-axis Coriolis coupling model to the measured A-symmetry internal rotation substate transitions was found to be successful. A total of over 1900 transitions were fitted for J values up to 76 and K a up to 24, resulting in determined vibrational separation between the two states Δ E = 6.2070246 ( 14 ) cm−1, and Coriolis coefficients | ζ 13 , 21 a | = 0.378, | ζ 13 , 21 b | = 0.127, in good agreement with quantum chemistry calculations. The new line catalog was used to model ALMA spectra of Titan’s atmosphere from 2016, fitting many weak lines not previously modeled. By including the vibrationally excited lines of C2H5CN and a new partition function, we derive a disk-averaged volume mixing ratio estimate in 2016 of 7.8 ± 0.2 ppb assumed constant above 300 km.

The Visual and Infrared Mapping Spectrometer (VIMS) measurements of non-Local Thermodinamic Equilibrium (non-LTE) emissions of CH 4 , HCN and C 2 H 2 in the near-infrared represent a dataset with unique coverage to study Titan's upper atmosphere in the altitude range from 500 to 1000 km. This region is the key to a better understanding of the middle atmosphere circulation. The assessment of the latitudinal and seasonal variations in the distributions of HCN and C 2 H 2 could give important hints about it and complement the Composite InfraRed Spectrometer (CIRS) observations, that target the atmosphere below 500 km. The measurement of CH 4 and HCN above 900 km can also help in understanding the Ion and Neutral Mass Spectrometer (INMS) observations near and above 1000 km. We have analysed the VIMS daytime spectra in the 2.9–3.4 μm region measured from 2004 to 2012 that span from the mid-northern winter through mid-northern spring Titan seasons. The measurements exhibit very strong non-LTE emissions of CH 4 , HCN and C 2 H 2 . Non-LTE vibrational temperatures have been calculated for the emitting levels of the three molecules, and have been used in the inversion of their abundances in the 500–1100 km region. The retrieved abundances have been averaged in latitudinal bins and in two seasons: north hemisphere winter (2004–2009) and north hemisphere early spring (2010−2012). The C 2 H 2 average profile, retrieved for the first time from VIMS measurements, shows good agreement with UltraViolet Imaging Spectrograph (UVIS) measurements below 850 km, while higher values are found above that altitude. The HCN volume mixing ratio (VMR) shows an enhancement at the north pole during winter at all altitudes (from ∼700 km up to near 1000 km) and at the north and south poles during spring below 900 km. Also, the average C 2 H 2 abundance is larger at both poles during spring below 800 km, while no significant variation is seen during winter. For CH 4 we found enhancements above 800 km at the north pole during winter and at both poles during spring. Our results suggest that the middle atmosphere circulation on Titan extends well above the 500 km level, up to 750–800 km or even higher if we assume that the CH 4 concentration above 800 km is mainly controlled by the circulation. The behavior of CH 4 at the winter pole above 800 km is in line with the strong zonal winds suggested to explain INMS observations, although it can also be explained by the slower photo-dissociation occurring during polar winter. Despite the poor statistic at the polar regions, our results represent a unique dataset that could help to improve our understanding of Titan's atmosphere above 500 km. © 2019 Elsevier Inc., This research was completed thanks to the financial support of the Italian Space Agency (ASI) and NASA through the Cassini project. The IAA team was supported by the Spanish MICINN under project ESP2014-54362-P and EC FEDER funds. MGC was financially supported by MINECO through its 'Ramon y Cajal' subprogram.

This study assesses antioxidant results as a biodiesel additive as fuels in the diesel engine. Biodiesel usage into diesel engine decreases the dependence on imported petroleum and yields benefits like reduction in global warming and engine exhaust emissions. However, inherent drawbacks like lower CV, higher viscosity, and density while increased SFC and NOx emissions limit the biodiesel application in engines. In this way, the additives in the form of antioxidant play a prominent role to mitigate the drawbacks of biodiesel. This investigation main cause to decrease NOx emissions by useof DPPD additive with biodiesel blends. This study uses three different Diesel, B20, B20DPPD1000 test fuels to be prepared at a different volume mixing ratio. This results reported that increase BTE and reduce BSEC of B20 fuel with DPPD additive as contrasted to other test fuels. Also the vital decrease of NOx and CO emissions but slightly increase HC emissions obtained use of B20 fuel with additive.

Aims. We study the seasonal evolution of Titan’s lower stratosphere (around 15 mbar) in order to better understand the atmospheric dynamics and chemistry in this part of the atmosphere. Methods. We analysed Cassini/CIRS far-IR observations from 2006 to 2016 in order to measure the seasonal variations of three photochemical by-products: C4H2, C3H4, and C2N2. Results. We show that the abundances of these three gases have evolved significantly at northern and southern high latitudes since 2006. We measure a sudden and steep increase of the volume mixing ratios of C4H2, C3H4, and C2N2 at the south pole from 2012 to 2013, whereas the abundances of these gases remained approximately constant at the north pole over the same period. At northern mid-latitudes, C2N2 and C4H2 abundances decrease after 2012 while C3H4 abundances stay constant. The comparison of these volume mixing ratio variations with the predictions of photochemical and dynamical models provides constraints on the seasonal evolution of atmospheric circulation and chemical processes at play.

In this work we present the evolution of tropospheric nitrogen dioxide (NO2) content over several important European cities during 2005–2014 using space observations and ground-based in-situ measurements. The NO2 content was derived using the daily observations provided by the Ozone Monitoring Instrument (OMI), while the NO2 volume mixing ratio measurements were obtained from the European Environment Agency (EEA) air quality monitoring stations database. The European cities selected are: Athens (37.98° N, 23.72° E), Berlin (52.51° N, 13.41° E), Bucharest (44.43° N, 26.10° E), Madrid (40.38° N, 3.71° W), Lisbon (38.71° N, 9.13° W), Paris (48.85° N, 2.35° E), Rome (41.9° N, 12.50° E), and Rotterdam (51.91° N, 4.46° E). We show that OMI NO2 tropospheric column data can be used to assess the evolution of NO2 over important European cities. According to the statistical analysis, using the seasonal variation, we found good correlations (R > 0.50) between OMI and ground-based in-situ observations for all of the cities presented in this work. Highest correlation coefficients (R > 0.80) between ground-based monitoring stations and OMI observations were calculated for the cities of Berlin, Madrid, and Rome. Both types of observations, in-situ and remote sensing, show an NO2 negative trend for all of locations presented in this study.

With inadequate information from sensors onboard the SCISAT satellite to generate accurate pointing information, tangent heights for the solar occultation measurements collected by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) are determined from features in the measured spectra. For version 4.0 processing of the ACE-FTS data, tangent heights below 18 km are generated from the N2 collision induced absorption continuum near 2500 cm−1. Because this tangent height determination requires no assumptions on CO2 concentrations in this altitude region (unlike previous processing versions), ACE-FTS version 4.0 includes retrieved CO2 volume mixing ratio profiles below 18 km as a standard product.

A LEO-ground infrared laser occultation (LGIO) technique is proposed to retrieve the greenhouse gas (GHG) profiles at a specific location, which is practical for monitoring regional weather and climate changes. The harmony search (HS) algorithm with ensemble consideration is applied to retrieve the volume mixing ratio (VMR) profiles of three major GHGs (CO 2 , CH 4 and N 2 O) and H 2 O. The vertical resolution is 1 km below 20 km. The error of VMR with this method is below 10, 5, 5 and 3 % for H 2 O, CH 4 , N 2 O and CO 2 , respectively, at the altitudes from ground to 45 km.

Research and characterizing the ozone profiles and Ozone Depleting Substances (ODS) in Indonesia is a satellite data-based research activities. The aim of the study was to obtain the characteristics of ozone in Indonesia as well as the contribution of ODS to the variability of ozone. By performing a data inventory based on satellite data, analyze the pattern of annual, seasonal and perform linkage analysis of the contribution of ODS changes to the conditions of ozone. Daily data of vertical profiles of ozone and in the form of volume mixing ratio (vmr) with format HDF (Hierarchical Data Format) is extracted to the territory of Indonesia to take parameters as latitude, longitude, and concentration. Then converted to Excel format with the help of data processing software of MATLAB. Results obtained in the form of ozone characteristics in Indonesia, the percentage of contribution to the variability of ozone also contribution to the variability of ozone in Indonesia in several levels of height. By using Microwave Limb Sounders (MLS) AURA satellite data in the period of 2005 to 2013 characteristics of monthly vertical profiles of ozone in Indonesia has been obtained. The ODS studied were ClO and BrO. Peak of vertical profiles of ozone occurs at a pressure of 10 hPa or altitude of 25.9 km. ClO peak occurs at a pressure of 2.1 hPa or altitude of 30.6 km and BrO reached the peak at 14 hPa or altitude of 24.5 km. When ClO and BrO reach a maximum concentration at stratosphere then ozone molecules is potentially damaging or decrease in the stratosphere. Temporal variations of ozone showed decrease when ODS concentrations increased (particularly ClO and BrO). Linear regression of ozone with ozone showed a negative correlation coefficient which indicates there is a strong relationship between ozone concentrations decline in pressure of 14 hPa when BrO reach the maximum. Likewise for ClO which also showed a negative correlation with the decrease in ozone concentration. ClO contribution to the decreasing of ozone in Indonesia was marked by every addition of 0.01 ppb ClO will reduce ozone of 0.00583 ppm (5.83 ppb). While any increase of 0.01 ppb of BrO will decrease 0.03 ppb of ozone.

The relationship between surface-level observations of daily maxima in ozone (O 3max ) volume mixing ratio and ambient air temperature (Tmax) has been studied at an urban site, i.e. Pune (18.4°N, 73.8°E), India during 2003-04. The mixing ratios of O 3max were found to be highest during winter to pre-monsoon period and lowest in the monsoon season. The dependence of O 3max levels on T max has been quantified using the linear regression fit for the different seasons. However, except for the monsoon season, reasonably good correlations between O 3max and T max were noticed. The correlation between daily O 3max concentration and minimum NO x (NO x min ) concentration was also studied to assess the importance of photochemical mechanism mainly reduction in the loss due to titration. Overall, the strong dependencies of O 3max on Tmax and NO x min signify the role of both meteorological and photochemical processes during most months of a year. The positive slopes of ΔO 3max /ΔT max and ΔO 3max /ΔNO xmin clearly indicate the role of significant production and accumulation of O 3 under high temperature and low NO x conditions respectively, during winter and premonsoon seasons. The statistical analysis of O 3 in relation with the key meteorological and chemical parameters is important to understand the sensitivity of secondary pollutants on various controlling factors.