| 1. |
- Gordon, I.E., et al.
(författare)
-
The HITRAN2020 molecular spectroscopic database
- 2022
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 277
-
Tidskriftsartikel (refereegranskat)abstract
- The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition.
|
|
| 2. |
- Khosrawi, Farahnaz, et al.
(författare)
-
Validation of CFC-12 measurements from the Improved Limb Atmospheric Spectrometer (ILAS)
- 2004
-
Ingår i: Journal of Geophysical Research. ; 109:D06311
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of CFC-12 were made by the Improved Limb Atmospheric Spectrometer (ILAS) between 57 N and 72 N in the Northern Hemisphere and between 64 S and 89 S in the Southern Hemisphere. ILAS was launched on 17 August 1996 on board the Advanced Earth Observing Satellite (ADEOS). The ILAS validation balloon campaigns were carried out from Kiruna, Sweden (68 N, 21 E), in February and March 1997 and from Fairbanks, Alaska (65 N, 148 W), in April and May 1997. During these validation balloon campaigns, CFC-12 was measured with the in situ instruments ASTRID, BONBON, and SAKURA and the remote sensing spectrometers MIPAS-B, FIRS-2, and MkIV. ILAS version 6.0 CFC-12 profiles obtained at the nearest location to the validation balloon measurement are compared with these validation balloon measurements. The quality of ILAS CFC-12 data processed with the version 6.0 algorithm improved significantly compared to previous versions. Low relative differences between ILAS CFC-12 and the correlative measurements of about 10% were found between 13 and 20 km. The comparison of vertical profiles shows that ILAS CFC-12 data are useful below about 20–22 km inside the vortex and below about 25 km outside the vortex. However, at greater altitudes the relative percentage difference increases very strongly with increasing altitude. Further, correlations of CFC-12 with N2O show a good agreement with the correlative measurements for N2O values of N2O > 150 ppbv. In summary, ILAS CFC-12 data are now suitable for scientific studies in the lower stratosphere.
|
|
| 3. |
- Kleinböhl, A., et al.
(författare)
-
Constraints for the photolysis rate and the equilibrium constant of ClO-dimer from airborne and balloon-borne measurements of chlorine compounds
- 2014
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 119:11, s. 6916--6937-6937
-
Tidskriftsartikel (refereegranskat)abstract
- We analyze measurements of ClO across the terminator taken by the Airborne Submillimeter Radiometer (ASUR) in the activated vortices of the Arctic winters of 1995/1996, 1996/1997, and 1999/2000 to evaluate the plausibility of various determinations of the ClO-dimer photolysis cross section and the rate constant controlling the thermal equilibrium between ClO-dimer and ClO. We use measured ClO during sunlit conditions to estimate total active chlorine (ClOx). As the measurements suggest nearly full chlorine activation in winter 1999/2000, we compare ClOx estimates based on various photolysis frequencies of ClO-dimer with total available inorganic chlorine (Cly), estimated from an N2O-Cly correlation established by a balloon-borne MkIV interferometer measurement. Only ClO-dimer cross sections leading to the fastest photolysis frequencies in the literature (including the latest evaluation by the Jet Propulsion Laboratory) give ClOx mixing ratios that overlap with the estimated range of available Cly. Slower photolysis rates lead to ClOx values that are higher than available Cly. We use the ClOx calculated from sunlit ClO measurements to estimate ClO in darkness based on different equilibrium constants, and compare it with ASUR ClO measurements before sunrise at high solar zenith angles. Calculations with equilibrium constants published in recent evaluations of the Jet Propulsion Laboratory give good agreement with observed ClO mixing ratios. Equilibrium constants leading to a higher ClO/ClOx ratio in darkness yield ClO values that tend to exceed observed abundances. Perturbing the rates for the ClO + BrO reaction in a manner that increases OClO formation and decreases BrCl formation leads to lower ClO values calculated for twilight conditions after sunset, resulting in better agreement with ASUR measurements.
|
|
| 4. |
- Lambert, A., et al.
(författare)
-
Validation of the Aura Microwave Limb Sounder middle atmosphere water vapor and nitrous oxide measurements
- 2007
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D24
-
Tidskriftsartikel (refereegranskat)abstract
- The quality of the version 2.2 (v2.2) middle atmosphere water vapor and nitrous oxide measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System (EOS) Aura satellite is assessed. The impacts of the various sources of systematic error are estimated by a comprehensive set of retrieval simulations. Comparisons with correlative data sets from ground-based, balloon and satellite platforms operating in the UV/ visible, infrared and microwave regions of the spectrum are performed. Precision estimates are also validated, and recommendations are given on the data usage. The v2.2 H 2 O data have been improved over v1.5 by providing higher vertical resolution in the lower stratosphere and better precision above the stratopause. The single-profile precision is ∼0.2-0.3 ppmv (4-9%), and the vertical resolution is ∼3-4 km in the stratosphere. The precision and vertical resolution become worse with increasing height above the stratopause. Over the pressure range 0.1-0.01 hPa the precision degrades from 0.4 to 1.1 ppmv (6-34%), and the vertical resolution degrades to ∼12-16 km. The accuracy is estimated to be 0.2-0.5 ppmv (4-11%) for the pressure range 68-0.01 hPa. The scientifically useful range of the H 2 O data is from 316 to 0.002 hPa, although only the 82-0.002 hPa pressure range is validated here. Substantial improvement has been achieved in the v2.2 N 2 O data over v1.5 by reducing a significant low bias in the stratosphere and eliminating unrealistically high biased mixing ratios in the polar regions. The single-profile precision is ∼13-25 ppbv (7-38%), the vertical resolution is ∼4-6 km and the accuracy is estimated to be 3-70 ppbv (9-25%) for the pressure range 100-4.6 hPa. The scientifically useful range of the N 2 O data is from 100 to 1 hPa. Copyright 2007 by the American Geophysical Union.
|
|
| 5. |
- Santee, M.L., et al.
(författare)
-
Validation of the Aura Microwave Limb Sounder ClO Measurements
- 2008
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:D15
-
Tidskriftsartikel (refereegranskat)abstract
- We assess the quality of the version 2.2 (v2.2) ClO measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System Aura satellite. The MLS v2.2 ClO data are scientifically useful over the range 100 to 1 hPa, with a single- profile precision of similar to 0.1 ppbv throughout most of the vertical domain. Vertical resolution is similar to 3-4 km. Comparisons with climatology and correlative measurements from a variety of different platforms indicate that both the amplitude and the altitude of the peak in the ClO profile in the upper stratosphere are well determined by MLS. The latitudinal and seasonal variations in the ClO distribution in the lower stratosphere are also well determined, but a substantial negative bias is present in both daytime and nighttime mixing ratios at retrieval levels below (i. e., pressures larger than) 22 hPa. Outside of the winter polar vortices, this negative bias can be eliminated by subtracting gridded or zonal mean nighttime values from the individual daytime measurements. In studies for which knowledge of lower stratospheric ClO mixing ratios inside the winter polar vortices to better than a few tenths of a ppbv is needed, however, day - night differences are not recommended and the negative bias must be corrected for by subtracting the estimated value of the bias from the individual measurements at each affected retrieval level.
|
|
| 6. |
- Santee, M.L., et al.
(författare)
-
Validation of the Aura Microwave Limb Sounder HNO3 Measurements
- 2007
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D24
-
Tidskriftsartikel (refereegranskat)abstract
- [1] We assess the quality of the version 2.2 (v2.2) HNO(3) measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System Aura satellite. The MLS HNO(3) product has been greatly improved over that in the previous version (v1.5), with smoother profiles, much more realistic behavior at the lowest retrieval levels, and correction of a high bias caused by an error in one of the spectroscopy files used in v1.5 processing. The v2.2 HNO(3) data are scientifically useful over the range 215 to 3.2 hPa, with single-profile precision of similar to 0.7 ppbv throughout. Vertical resolution is 3-4 km in the upper troposphere and lower stratosphere, degrading to similar to 5 km in the middle and upper stratosphere. The impact of various sources of systematic uncertainty has been quantified through a comprehensive set of retrieval simulations. In aggregate, systematic uncertainties are estimated to induce in the v2.2 HNO(3) measurements biases that vary with altitude between +/- 0.5 and +/- 2 ppbv and multiplicative errors of +/- 5-15% throughout the stratosphere, rising to similar to +/- 30% at 215 hPa. Consistent with this uncertainty analysis, comparisons with correlative data sets show that relative to HNO(3) measurements from ground- based, balloon- borne, and satellite instruments operating in both the infrared and microwave regions of the spectrum, MLS v2.2 HNO(3) mixing ratios are uniformly low by 10-30% throughout most of the stratosphere. Comparisons with in situ measurements made from the DC-8 and WB-57 aircraft in the upper troposphere and lowermost stratosphere indicate that the MLS HNO(3) values are low in this region as well, but are useful for scientific studies (with appropriate averaging).
|
|
