A comparison of OH nightglow volume emission rates as measured by SCIAMACHY and SABER

Hydroxyl (OH) short-wave infrared emissions arising from OH(4-2, 5-2, 8-5, 9-6) as measured by channel 6 of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) are used to derive concentrations of OH(v=4, 5, 8, and 9) between 80 and 96 km. Retrieved concentrations are used to simulate OH(5-3, 4-2) integrated radiances at 1.6 µm and OH(9-7, 8-6) at 2.0 µm as measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, which are not fully covered by the spectral range of SCIAMACHY measurements. On average, SABER “unfiltered” data are on the order of 40 % at 1.6 µm and 20 % at 2.0 µm larger than the simulations using SCIAMACHY data. “Unfiltered” SABER data are a product, which accounts for the shape, width, and transmission of the instrument's broadband filters, which do not cover the full ro-vibrational bands of the corresponding OH transitions. It is found that the discrepancy between SCIAMACHY and SABER data can be reduced by up to 50 %, if the filtering process is carried out manually using published SABER interference filter characteristics and the latest Einstein coefficients from the HITRAN database. Remaining differences are discussed with regard to model parameter uncertainties and radiometric calibration.

All Single-Mode-Fiber Supercontinuum Source Setup for Monitoring of Multiple Gases Applications

In this paper, a gas sensing system based on a conventional absorption technique using a single-mode-fiber supercontinuum source (SMF-SC) is presented. The SC source was implemented by channeling pulses from a microchip laser into a one kilometer long single-mode fiber (SMF), obtaining a flat high-spectrum with a bandwidth of up to 350 nm in the region from 1350 to 1700 nm, and high stability in power and wavelength. The supercontinuum radiation was used for simultaneously sensing water vapor and acetylene gas in the regions from 1350 to 1420 nm and 1510 to 1540 nm, respectively. The experimental results show that the absorption peaks of acetylene have a maximum depth of approximately 30 dB and contain about 60 strong lines in the R and P branches, demonstrating a high sensitivity of the sensing setup to acetylene. Finally, to verify the experimental results, the experimental spectra are compared to simulations obtained from the Hitran database. This shows that the implemented system can be used to develop sensors for applications in broadband absorption spectroscopy and as a low-cost absorption spectrophotometer of multiple gases.

HITRAN2020: An overview of what to expect

<p>The HITRAN database is an integral component of numerous atmospheric radiative transfer models and it is therefore essential that the database contains the most appropriate up-to-date spectroscopic parameters. To this end, the HITRAN2020 database is scheduled to be released at the end of this year.  The compilation of this edition (as is the tradition for the HITRAN database) exemplifies the efficiency and necessity of worldwide scientific collaborations. It is a titanic effort of experimentalists, theoreticians and atmospheric scientists, who measure, calculate and validate the HITRAN data.</p><p>The HITRAN line-by-line lists for almost all 49 molecules have been updated in comparison to HITRAN2016 (Gordon et al., 2017), the previous compilation. The extent of these updates depend on the molecule, but range from small adjustments for a few lines of an individual molecule to complete replacements of line lists and the introduction of new isotopologues. Many new vibrational bands have been added to the database, thereby extending the spectral coverage and completeness of the datasets. In addition the accuracy of the parameters for major atmospheric absorbers has been substantially increased, often featuring sub-percent uncertainties.</p><p>Furthermore, the amount of parameters has also been significantly increased. For example, HITRAN2020 will now incorporate non-Voigt line profiles for many gases, broadening by water vapour (Tan et al., 2019), as well as updated collision induced absorption sets (Karman et al., 2019). The HITRAN2020 edition will continue taking advantage of the new structure and interface available at www.hitran.org (Hill et al., 2016) and the HITRAN Application Programming Interface (Kochanov et al., 2016).</p><p>This talk will provide a summary of these updates, emphasizing details of some of the most important or drastic improvements.</p><p><strong>References:</strong></p><p>Gordon, I.E., .et al., (2017), <em>JQSRT</em> <strong>203</strong>, 3–69.  (doi:10.1016/j.jqsrt.2017.06.038)</p><p>Hill, C., et al., (2016), <em>JQSRT</em> <strong>177</strong>, 4–14.  (doi:10.1016/j.jqsrt.2015.12.012)</p><p>Karman, T., et al. (2019), <em>Icarus</em> <strong>328</strong>, 160–175.  (doi:10.1016/j.icarus.2019.02.034)</p><p>Kochanov, R.V., et al.,( 2016), <em>JQSRT</em> <strong>177</strong>, 15–30.  (doi:10.1016/j.jqsrt.2016.03.005)</p><p>Tan, Y., et al., (2019),<em> J. Geophys. Res. Atmos.</em> <strong>124</strong>, 11580-11594. (doi:10.1029/2019JD030929)</p><p> </p>

A comparison of OH nightglow volume emission rates as measured by SCIAMACHY and SABER

<p>Hydroxyl (OH) short-wave infrared emissions arising from OH(4-2, 5-2, 8-5, 9-6) as measured by channel 6 of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) are used to derive OH concentrations of OH(v=4, 5, 8, and 9) between 80 km and 96 km. Retrieved concentrations are used to simulate integrated radiances at 1.6 um and 2.0 um as measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, which are not fully covered by the spectral range of SCIAMACHY. On average, SABER 'unfiltered' data is on the order of 40% (at 1.6 um) and 20% (at 2.0 um) larger than the simulations using SCIAMACHY data. 'Unfiltered' SABER data is a product, which accounts for the shape, width, and transmission of the instrument’s broadband filters, which do not cover the full ro-vibrational bands of the corresponding OH transitions. It is found that the discrepancy between SCIAMACHY and SABER data can be reduced by more than 50%, if the unfiltering process is carried out manually using published SABER interference filter characteristics and latest Einstein coefficients from the HITRAN database. Remaining differences are discussed with regard to model parameter uncertainties and radiometric calibration.</p>