| 1. |
- Jin, J.J., et al.
(författare)
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Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N2O), and methane (CH4) with observations from Odin/SMR, ACE-FTS, and Aura/MLS
- 2009
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 9, s. 3233-3252
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Tidskriftsartikel (refereegranskat)abstract
- Simulations of CO, N2O and CH4 from a coupled chemistry-climate model (CMAM) are compared with satellite measurements from Odin Sub-Millimeter Radiometer (Odin/SMR), Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), and Aura Microwave Limb Sounder (Aura/MLS). Pressure-latitude cross-sections and seasonal time series demonstrate that CMAM reproduces the observed global CO, N2O, and CH4 distributions quite well. Generally, excellent agreement with measurements is found between CO simulations and observations in the stratosphere and mesosphere. Differences between the simulations and the ACE-FTS observations are generally within 30%, and the differences between CMAM results and SMR and MLS observations are slightly larger. These differences are comparable with the difference between the instruments in the upper stratosphere and mesosphere. Comparisons of N2O show that CMAM results are usually within 15% of the measurements in the lower and middle stratosphere, and the observations are close to each other. However, the standard version of CMAM has a low N2O bias in the upper stratosphere. The CMAM CH4 distribution also reproduces the observations in the lower stratosphere, but has a similar but smaller negative bias in the upper stratosphere. The negative bias may be due to that the gravity drag is not fully resolved in the model. The simulated polar CO evolution in the Arctic and Antarctic agrees with the ACE and MLS observations. CO measurements from 2006 show evidence of enhanced descent of air from the mesosphere into the stratosphere in the Arctic after strong stratospheric sudden warmings (SSWs). CMAM also shows strong descent of air after SSWs. In the tropics, CMAM captures the annual oscillation in the lower stratosphere and the semiannual oscillations at the stratopause and mesopause seen in Aura/MLS CO and N2O observations and in Odin/SMR N2O observations. The Odin/SMR and Aura/MLS N2O observations also show a quasi-biennial oscillation (QBO) in the upper stratosphere, whereas, the CMAM does not have QBO included. This study confirms that CMAM is able to simulate middle atmospheric transport processes reasonably well.
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| 2. |
- Lambert, A., et al.
(författare)
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Validation of the Aura Microwave Limb Sounder middle atmosphere water vapor and nitrous oxide measurements
- 2007
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D24
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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.
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| 3. |
- Sheese, P. E., et al.
(författare)
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Odin observations of Antarctic nighttime NO densities in the mesosphere - lower thermosphere and observations of a lower NO layer
- 2013
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202 .- 2169-897X. ; 118:13, s. 7414-7425
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Tidskriftsartikel (refereegranskat)abstract
- The Optical Spectrograph and Infrared Imaging System (OSIRIS) on the Odin satellite currently has an eight-year dataset of nighttime Antarctic nitric oxide densities, [NO], in the mesosphere–lower thermosphere (MLT) region. In this work, the OSIRIS data are compared with a similar data set from the Sub-Millimeter Radiometer (SMR), also on the Odin satellite. Both of the Odin data sets are compared with twilight [NO] from the Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE-FTS) on the SciSat-I satellite. Direct comparisons of OSIRIS and SMR profiles show large differences, indicating that the individual [NO] profiles of one or both data sets may not be valid. However, when comparing averaged [NO], variations on timescales of weeks-years in all three data sets are in good agreement and correspond to the 27 day and 11 year solar cycles. The averaged OSIRIS values are typically 10% greater than SMR and 30% greater than ACE-FTS, which are within the estimated OSIRIS systematic uncertainties. These results suggest that the satellite-derived data sets can be used for determining polar-mean NO climatology and variations on timescales of weeks-years. The OSIRIS and SMR nighttime data sets show that the [NO] peak height in the MLT decreases throughout the autumn, from an altitude near or above 100 km to a minimum altitude ranging from 90 to 95 km around winter solstice. A similar decrease in [NO] peak height is observed in modeled NO climatology from the Specified Dynamics–Whole Atmosphere Community Climate Model (SD-WACCM), although the SD-WACCM climatology exhibits a decrease throughout autumn from 107 km down to 102 km. The results suggest that global climate models require more sophisticated auroral forcing simulations in order to reproduce observed NO variations in this region.
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| 4. |
- Wang, D.Y., et al.
(författare)
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Validation of nitric acid retrieved by the IMK-IAA processor from MIPAS/ENVISAT measurements
- 2007
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 7, s. 721-738
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Tidskriftsartikel (refereegranskat)abstract
- The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVISAT satellite provides profiles of temperature and various trace-gases from limb-viewing mid-infrared emission measurements. The stratospheric nitric acid (HNO(3)) from September 2002 to March 2004 was retrieved from the MIPAS observations using the science-oriented data processor developed at the Institut fur Meteorologie und Klimaforschung (IMK), which is complemented by the component of non-local thermodynamic equilibrium (non-LTE) treatment from the Instituto de Astrofisica de Andalucia (IAA). The IMK-IAA research product, different from the ESA operational product, is validated in this paper by comparison with a number of reference data sets. Individual HNO3 profiles of the IMK-IAA MIPAS show good agreement with those of the balloon-borne version of MIPAS (MIPAS-B) and the infrared spectrometer MkIV, with small differences of less than 0.5 ppbv throughout the entire altitude range up to about 38 km, and below 0.2 ppbv above 30 km. However, the degree of consistency is largely affected by their temporal and spatial coincidence, and differences of 1 to 2 ppbv may be observed between 22 and 26 km at high latitudes near the vortex boundary, due to large horizontal inhomogeneity of HNO(3). Statistical comparisons of MIPAS IMK-IAA HNO(3) VMRs with respect to those of satellite measurements of Odin/SMR, ILAS-II, ACE-FTS, as well as the MIPAS ESA product show good consistency. The mean differences are generally +/- 0.5 ppbv and standard deviations of the differences are of 0.5 to 1.5 ppbv. The maximum differences are 2.0 ppbv around 20 to 25 km. This gives confidence in the general reliability of MIPAS HNO(3) VMR data and the other three satellite data sets.
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| 5. |
- Koo, J. H., et al.
(författare)
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Global climatology based on the ACE-FTS version 3.5 dataset: Addition of mesospheric levels and carbon-containing species in the UTLS
- 2017
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073. ; 186, s. 52-62
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new climatology based on, the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) version 3.5 data set from February 2004 to February 2013. This extends the ACE-FTS climatology to include profile information in the mesosphere and carbon-containing species in the upper troposphere and lower stratosphere. Climatologies of 21 species, based on nine years of observations, are calculated, providing the most comprehensive and self-consistent climatology available from limb-viewing satellite measurements. Pressure levels from the upper troposphere to the mesosphere and lower thermosphere are included with similar to 3 to 4 km vertical resolution up to 10(-4) hPa (similar to 105 km). Volume mixing ratio values are filtered prior to the climatology estimation using the ACE-FTS data quality recommendations. The multi-year mean climatology contains zonal mean profiles for monthly and three-monthly (DJF, MAM, JJA, and SON) periods. These are provided with 5-degree spacing in either latitude or equivalent latitude. Also, the local daytime and nighttime distributions are provided separately for nitrogen-containing species, enabling diurnal differences to be investigated. Based on this climatology, examples of typical spatiotemporal patterns for trace gases in the mesosphere and for carbon-containing gases in the upper troposphere and lower stratosphere are discussed. (C) 2016 Elsevier Ltd. All rights reserved.
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| 6. |
- Carleer, M. R., et al.
(författare)
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Validation of water vapour profiles from the Atmospheric Chemistry Experiment (ACE)
- 2008
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Ingår i: Atmospheric Chemistry and Physics Discussion: An Interactive Open Access Journal of the European Geosciences Union. ; 8:2, s. 4499-4559
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Tidskriftsartikel (refereegranskat)abstract
- The Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Water vapour (H2O), one of the most important molecules for climate and atmospheric chemistry, is one of the key species provided by the two principal instruments, the infrared Fourier Transform Spectrometer (ACE-FTS) and the MAESTRO UV-Visible spectrometer (ACE-MAESTRO). The first instrument performs measurements on several lines in the 1362–2137 cm−1 range, from which vertically resolved H2O concentration profiles are retrieved, from 7 to 90 km altitude. ACE-MAESTRO measures profiles using the water absorption band in the near infrared part of the spectrum at 926.0–969.7 nm. This paper presents a comprehensive validation of the ACE-FTS profiles. We have compared the H2O volume mixing ratio profiles with space-borne (SAGE II, HALOE, POAM III, MIPAS, SMR) observations and measurements from balloon-borne frostpoint hygrometers and a ground based lidar. We show that the ACE-FTS measurements provide H2O profiles with small retrieval uncertainties in the stratosphere (better than 5% from 15 to 70 km, gradually increasing above). The situation is unclear in the upper troposphere, due mainly to the high variability of the water vapour volume mixing ratio in this region. A new water vapour data product from the ACE-MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) is also presented and initial comparisons with ACE-FTS are discussed.
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| 7. |
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| 8. |
- Jin, J.J., et al.
(författare)
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Co-located ACE-FTS and Odin/SMR stratospheric-mesospheric CO 2004 measurements and comparison with a GCM
- 2005
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 32:15
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a comparison of co-located and near simultaneous CO measurements from January to May, 2004 and from the Arctic to southern polar regions using the ACE-FTS, in solar occultation mode, and the Odin/SMR, which measures atmospheric emission. We find that there is excellent agreement between the two instruments at the locations investigated over 4 orders of magnitude from the lower stratosphere to the lower thermosphere. There is also good agreement with the CMAM model simulation from 20 km to 90 km in sub-tropical and tropical latitudes but poorer agreement in the upper stratosphere and lower mesosphere in winter polar regions. For the Arctic in March 2004 this can be attributed, at least partly, to the unique dynamical processes in the stratosphere in the winter of 2003 - 2004. Clearly CO measurements from these instruments will provide a useful tool for testing model transport from the troposphere to the thermosphere.
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| 9. |
- Jones, A., et al.
(författare)
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Technical Note: A trace gas climatology derived from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) data set
- 2012
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:11, s. 5207-5220
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Tidskriftsartikel (refereegranskat)abstract
- The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) aboard the Canadian satellite SCISAT (launched in August 2003) was designed to investigate the composition of the upper troposphere, stratosphere, and mesosphere. ACE-FTS utilizes solar occultation to measure temperature and pressure as well as vertical profiles of over thirty chemical species including O-3, H2O, CH4, N2O, CO, NO, NO2, N2O5, HNO3, HCl, ClONO2, CCl3F, CCl2F2, and HF. Global coverage for each species is obtained approximately over a three month period and measurements are made with a vertical resolution of typically 3-4 km. A quality-controlled climatology has been created for each of these 14 baseline species, where individual profiles are averaged over the period of February 2004 to February 2009. Measurements used are from the ACE-FTS version 2.2 data set including updates for O-3 and N2O5. The climatological fields are provided on a monthly and three-monthly basis (DJF, MAM, JJA, SON) at 5 degree latitude and equivalent latitude spacing and on 28 pressure surfaces (26 of which are defined by the Stratospheric Processes And their Role in Climate (SPARC) Chemistry-Climate Model Validation Activity). The ACE-FTS climatological data set is available through the ACE website.
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| 10. |
- Kerzenmacher, T., et al.
(författare)
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Validation of NO2 and NO from the Atmospheric Chemistry Experiment (ACE)
- 2008
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8:19, s. 5801--5841-
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Tidskriftsartikel (refereegranskat)abstract
- Vertical profiles of NO2 and NO have been obtained from solar occultation measurements by the Atmospheric Chemistry Experiment (ACE), using an infrared Fourier Transform Spectrometer (ACE-FTS) and (for NO2) an ultraviolet-visible-near-infrared spectrometer, MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation). In this paper, the quality of the ACE-FTS version 2.2 NO2 and NO and the MAESTRO version 1.2 NO2 data are assessed using other solar occultation measurements (HALOE, SAGE II, SAGE III, POAM III, SCIAMACHY), stellar occultation measurements (GOMOS), limb measurements (MIPAS, OSIRIS), nadir measurements (SCIAMACHY), balloon-borne measurements (SPIRALE, SAOZ) and ground-based measurements (UV-VIS, FTIR). Time differences between the comparison measurements were reduced using either a tight coincidence criterion, or where possible, chemical box models. ACE-FTS NO2 and NO and the MAESTRO NO2 are generally consistent with the correlative data. The ACE-FTS and MAESTRO NO2 volume mixing ratio (VMR) profiles agree with the profiles from other satellite data sets to within about 20% between 25 and 40 km, with the exception of MIPAS ESA (for ACE-FTS) and SAGE II (for ACE-FTS (sunrise) and MAESTRO) and suggest a negative bias between 23 and 40 km of about 10%. MAESTRO reports larger VMR values than the ACE-FTS. In comparisons with HALOE, ACE-FTS NO VMRs typically (on average) agree to ±8% from 22 to 64 km and to +10% from 93 to 105 km, with maxima of 21% and 36%, respectively. Partial column comparisons for NO2 show that there is quite good agreement between the ACE instruments and the FTIRs, with a mean difference of +7.3% for ACE-FTS and +12.8% for MAESTRO.
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