Global retrieval of solar induced fluorescence emitted by terrestrial vegetation can provide an unprecedented measure for photosynthetic efficiency. The GOSAT (JAXA, launched Feb. 2009) and OCO‐2 ...(NASA, to be launched 2013) satellites record high‐resolution spectra in the O2 A‐band region, overlapping part of the chlorophyll fluorescence spectrum. We show that fluorescence cannot be unambiguously discriminated from atmospheric scattering effects using O2 absorption lines. This can cause systematic biases in retrieved scattering parameters (aerosol optical thickness, aerosol height, surface pressure, surface albedo) if fluorescence is neglected. Hence, we demonstrate an efficient alternative fluorescence least‐squares retrieval method based solely on strong Fraunhofer lines in the vicinity of the O2 A‐band, disentangling fluorescence from scattering effects. Not only does the Fraunhofer line fit produce a more accurate estimate of fluorescence emission, but it also allows improved retrievals of atmospheric aerosols from the O2 A‐band.
Atmospheric column abundances of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and nitrous oxide (N2O) have been measured above the South Coast air basin (SCB), a densely populated urban ...region of Southern California, USA, which includes Los Angeles and the surrounding suburbs. Large diurnal variations in CO and CH4 are observed which correlate well with those in CO2. Weaker correlations are seen between N2O and CO2, with large uncertainties. We compute yearly SCB emissions of CO and CH4 to be 1.4 ± 0.3 Tg CO and 0.6 ± 0.1 Tg CH4. We compare our calculated emissions to the California Air Resources Board (CARB) and the Emission Database for Global Atmospheric Research (EDGAR) estimates. Our measurements confirm that urban emissions are a significant source of CH4 and in fact may be substantially higher than currently estimated. If our emissions are typical of other urban centers, these findings suggest that urban emissions could contribute 7–15% to the global anthropogenic budget of methane.
The HITRAN2016 molecular spectroscopic database Gordon, I.E.; Rothman, L.S.; Hill, C. ...
Journal of Quantitative Spectroscopy & Radiative Transfer/Journal of quantitative spectroscopy & radiative transfer,
12/2017, Letnik:
203
Journal Article
Recenzirano
Odprti dostop
•HITRAN2016 molecular spectroscopic database is described.•Dynamic web interface at www.hitran.org is introduced.•HITRAN Application Programming Interface is introduced.•Substantial extent of the ...amount and quality of the data highlighted.•Many new spectroscopic parameters are now available in HITRAN.
This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.
Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed ...an approach for representing synoptic‐ and diurnal‐scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We disaggregated monthly GFED3 emissions during 2003–2009 to a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS)‐derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WF_ABBA) active fire observations. Daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of burning in savannas. These patterns were consistent with earlier field and modeling work characterizing fire behavior dynamics in different ecosystems. On diurnal timescales, our analysis of the GOES WF_ABBA active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top‐down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from multiple satellite sensors to improve daily emissions estimates.
Key Points
We developed an approach to distribute daily and hourly fire emissions
Daily and hourly patterns of fire activity varied among different land types
Daily and hourly fire emissions improved CO simulations
The HITRAN2012 molecular spectroscopic database Rothman, L.S.; Gordon, I.E.; Babikov, Y. ...
Journal of Quantitative Spectroscopy & Radiative Transfer/Journal of quantitative spectroscopy & radiative transfer,
November 2013, 2013-11-00, 20131101, 2013-11, Letnik:
130
Journal Article
Recenzirano
Odprti dostop
This paper describes the status of the 2012 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2008 and its updates during the ...intervening years. The HITRAN molecular absorption compilation is comprised of six major components structured into folders that are freely accessible on the internet. These folders consist of the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, ultraviolet spectroscopic parameters, aerosol indices of refraction, collision-induced absorption data, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, and validity. Molecules and isotopologues have been added that address the issues of atmospheres beyond the Earth. Also discussed is a new initiative that casts HITRAN into a relational database format that offers many advantages over the long-standing sequential text-based structure that has existed since the initial release of HITRAN in the early 1970s.
•A new edition of the HITRAN molecular spectroscopic database is described.•HITRAN now includes a large number of molecules and their isotopologues.•HITRAN is now applicable to planetary atmospheres in addition to terrestrial.•A new structure for the database is described.•Many new spectroscopic phenomena are now available for the user.
Abstract Previous research on substance use disorders (SUD) has yielded conflicting results concerning whether alexithymia is a state or trait, raising the question of how alexithymia should be ...addressed in the treatment of SUD-patients. The absolute and relative stabilities of alexithymia were assessed using the Toronto Alexithymia Scale (TAS-20) and its subscales. In total, 101 patients with SUD were assessed twice during a 3-week inpatient detoxification period while controlling for withdrawal symptoms and personality disorder traits. The relative stability of the total TAS-20 and subscales was moderate to high but showed remarkable differences between baseline low, moderate, and high alexithymic patients. A small reduction in the mean levels of the total TAS-20 scores and those of one subscale revealed the absence of absolute stability. The levels of alexithymia were unrelated to changes in withdrawal symptoms, including anxiety- and depression-like symptoms. The differences between low, moderate, and high alexithymic patients in terms of the change in alexithymia scores between baseline and follow-up indicated a strong regression to the mean. The findings suggest that alexithymia in SUD patients as measured using the TAS-20 is both a state and trait phenomenon and does not appear to be related to changes in anxiety- and depression-like symptoms.
We describe a method of evaluating systematic errors in measurements of total column dry-air mole fractions of CO2 (XCO2 ) from space, and we illustrate the method by applying it to the v2.8 ...Atmospheric CO2 Observations from Space retrievals of the Greenhouse Gases Observing Satellite (ACOS-GOSAT) measurements over land. The approach exploits the lack of large gradients in XCO2 south of 25° S to identify large-scale offsets and other biases in the ACOS-GOSAT data with several retrieval parameters and errors in instrument calibration. We demonstrate the effectiveness of the method by comparing the ACOS-GOSAT data in the Northern Hemisphere with ground truth provided by the Total Carbon Column Observing Network (TCCON). We use the observed correlation between free-tropospheric potential temperature and XCO2 in the Northern Hemisphere to define a dynamically informed coincidence criterion between the ground-based TCCON measurements and the ACOS-GOSAT measurements. We illustrate that this approach provides larger sample sizes, hence giving a more robust comparison than one that simply uses time, latitude and longitude criteria. Our results show that the agreement with the TCCON data improves after accounting for the systematic errors, but that extrapolation to conditions found outside the region south of 25° S may be problematic (e.g., high airmasses, large surface pressure biases, M-gain, measurements made over ocean). A preliminary evaluation of the improved v2.9 ACOS-GOSAT data is also discussed.
Classical molecular dynamics simulations (CMDS) are used for calculations of the collision-induced absorption (CIA) by pure N2 in the (2.1-2.2µm) region of the first overtone band. They lead to ...reasonable (±15%) agreement with the only two laboratory measurements available, at 97K and room temperature. Based on these experiment/theory comparisons, empirical corrections are made to the CMDS-calculated CIA of pure N2 in the 200-300K temperature range. In addition, the contribution of N2-O2 collisions is, in the absence of any laboratory measurement, calculated and a simple semiempirical model (the first of its kind) is built in order to predict the CIA of N2 under Earth atmosphere conditions. This is successfully validated by comparisons with ground-based atmospheric transmission spectra in the 2.1-2.2µm region. Key Points Molecular dynamics simulations of the N2-N2 collision-induced absorption near 2.16 micrometers Semiempirical simple modeling of the N2-air collision-induced absorption by N2 Successful comparisons with ground-based atmospheric transmission spectra
The column‐average dry air mole fractions of atmospheric carbon dioxide and methane and are inferred from observations of backscattered sunlight conducted by the Greenhouse gases Observing SATellite ...(GOSAT). Comparing the first year of GOSAT retrievals over land with colocated ground‐based observations of the Total Carbon Column Observing Network (TCCON), we find an average difference (bias) of −0.05% and −0.30% for and with a station‐to‐station variability (standard deviation of the bias) of 0.37% and 0.26% among the 6 considered TCCON sites. The root‐mean square deviation of the bias‐corrected satellite retrievals from colocated TCCON observations amounts to 2.8 ppm for and 0.015 ppm for Without any data averaging, the GOSAT records reproduce general source/sink patterns such as the seasonal cycle of suggesting the use of the satellite retrievals for constraining surface fluxes.
Key Points
Improved quality of XCO2 and XCH4 satellite retrievals due to refined methods
Source/sink patterns are dentifiable in the data record without averaging
Constrained surface flux modeling is the logical next step
The Total Carbon Column Observing Network (TCCON) is a ground-based network of Fourier Transform Spectrometer (FTS) sites around the globe, where the column abundances of CO2 , CH4 , N2 O, CO and O2 ...are measured. CO2 is constrained with a precision better than 0.25% (1-σ). To achieve a similarly high accuracy, calibration to World Meteorological Organization (WMO) standards is required. This paper introduces the first aircraft calibration campaign of five European TCCON sites and a mobile FTS instrument. A series of WMO standards in-situ profiles were obtained over European TCCON sites via aircraft and compared with retrievals of CO2 column amounts from the TCCON instruments. The results of the campaign show that the FTS measurements are consistently biased 1.1% ± 0.2% low with respect to WMO standards, in agreement with previous TCCON calibration campaigns. The standard a priori profile for the TCCON FTS retrievals is shown to not add a bias. The same calibration factor is generated using aircraft profiles as a priori and with the TCCON standard a priori. With a calibration to WMO standards, the highly precise TCCON CO2 measurements of total column concentrations provide a suitable database for the calibration and validation of nadir-viewing satellites.
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