| 1. |
- Baron, P., et al.
(författare)
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HO2 measurements in the stratosphere and the mesosphere from the sub-millimetre limb sounder Odin/SMR
- 2009
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Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 1366-5901 .- 0143-1161. ; 30:15-16, s. 4195-4208
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents observations of the hydroperoxy radical (HO 2 ) performed by the Odin/SMR instrument from the middle stratosphere to the upper mesosphere (35-90 km). The data set covers the period from October 2003 to December 2005 on a basis of one observation period of 24 hours each month. Odin/SMR can provide two zonal maps of HO 2 per day, with a vertical resolution of 10 km. The non-standard processing applied to the retrievals is described. The consistency between HO 2 observations from three periods in August 2004 demonstrates the robustness of the retrieval method. It also shows that the measurements are sensitive enough to detect changes in the middle and upper mesosphere. The retrieval needs further improvements for studying stratospheric variations. © 2009 Taylor & Francis.
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| 2. |
- Barret, B., et al.
(författare)
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Intercomparisons of trace gases profiles from the Odin/SMR and Aura/MLS limb sounders
- 2006
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 111:D21
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the intercomparison of O(3), HNO(3), ClO, N(2)O and CO profiles measured by the two spaceborne microwave instruments MLS ( Microwave Limb Sounder) and SMR ( Submillimetre Radiometer) on board the Aura and Odin satellites, respectively. We compared version 1.5 level 2 data from MLS with level 2 data produced by the French data processor version 222 and 225 and by the Swedish data processor version 2.0 for several days in September 2004 and in March 2005. For the five gases studied, an overall good agreement is found between both instruments. Most of the observed discrepancies between SMR and MLS are consistent with results from other intercomparison studies involving MLS or SMR. O(3) profiles retrieved from the SMR 501.8 GHz band are noisier than MLS profiles but mean biases between both instruments do not exceed 10%. SMR HNO(3) profiles are biased low relative to MLS's by similar to 30% above the profile peak. In the lower stratosphere, MLS ClO profiles are biased low by up to 0.3 ppbv relative to coincident SMR profiles, except in the Southern Hemisphere polar vortex in the presence of chlorine activation. N(2)O profiles from both instruments are in very good agreement with mean biases not exceeding 15%. Finally, the intercomparison between SMR and MLS CO profiles has shown a good agreement from the middle stratosphere to the middle mesosphere in spite of strong oscillations in the MLS profiles. In the upper mesosphere, MLS CO concentrations are biased high relative to SMR while negative values in the MLS retrievals are responsible for a negative bias in the tropics around 30 hPa.
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| 3. |
- Christensen, Ole Martin, 1984, et al.
(författare)
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Tomographic retrieval of water vapour and temperature around polar mesospheric clouds using Odin-SMR
- 2015
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 8:5, s. 1981-1999
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Tidskriftsartikel (refereegranskat)abstract
- A special observation mode of the Odin satellite provides the first simultaneous measurements of water vapour, temperature and polar mesospheric cloud (PMC) brightness over a large geographical area while still resolving both horizontal and vertical structures in the clouds and background atmosphere. The observation mode was activated during June, July and August of 2010 and 2011, and for latitudes between 50 and 82 degrees N. This paper focuses on the water vapour and temperature measurements carried out with Odin's sub-millimetre radiometer (SMR). The tomographic retrieval approach used provides water vapour and temperature between 75 and 90 km with a vertical resolution of about 2.5 km and a horizontal resolution of about 200 km. The precision of the measurements is estimated to 0.2 ppmv for water vapour and 2K for temperature. Due to limited information about the pressure at the measured altitudes, the results have large uncertainties (> 3 ppmv) in the retrieved water vapour. These errors, however, influence mainly the mean atmosphere retrieved for each orbit, and variations around this mean are still reliably captured by the measurements. SMR measurements are performed using two different mixer chains, denoted as frequency mode 19 and 13. Systematic differences between the two frontends have been noted. A first comparison with the Solar Occultation For Ice Experiment instrument (SOFIE) on-board the Aeronomy of Ice in the Mesosphere (AIM) satellite and the Fourier Transform Spectrometer of the Atmospheric Chemistry Experiment (ACE-FTS) on-board SCISAT indicates that the measurements using the frequency mode 19 have a significant low bias in both temperature (> 15 K) and water vapour (> 0.5 ppmv), while the measurements using frequency mode 13 agree with the other instruments considering estimated errors. PMC brightness data is provided by OSIRIS, Odin's other sensor. Combined SMR and OSIRIS data for some example orbits is considered. For these orbits, effects of PMCs on the water vapour distribution are clearly seen. Areas depleted of water vapour are found above layers with PMC, while regions of enhanced water vapour due to ice particle sedimentation are primarily placed between and under the clouds.
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| 4. |
- Dupuy, E., et al.
(författare)
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Strato-mesospheric Measurements of Carbon Monoxide with the Odin Sub-millimetre Radiometer: Retrieval and First Results
- 2004
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 31:20
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Tidskriftsartikel (refereegranskat)abstract
- The Sub-Millimetre Radiometer (SMR) aboard the Odin satellite has been measuring vertical profiles of atmospheric trace gases since August 2001. We present the inversion methodology developed for CO measurements and the first retrieval results. CO can be retrieved from a single scan measurement throughout the middle atmosphere, with a typical resolution of similar to3 km and a relative error of similar to10% to similar to25%. Retrieval results are evaluated through comparison with data from the Whole Atmosphere Community Climate Model (WACCM) and observations of the Improved Stratospheric and Mesospheric Sounder (ISAMS) on board the Upper Atmospheric Research Satellite (UARS). Considering the large natural variability of CO, the SMR retrievals give good confirmation of the WACCM results, with an overall agreement within a factor of 2. ISAMS abundances are higher than SMR mixing ratios by a factor of 5-10 above 0.5 hPa from similar to80degreesS to similar to50degreesN.
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| 5. |
- Forkman, Peter, 1959, et al.
(författare)
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Six years of mesospheric CO estimated from ground-based frequency-switched microwave radiometry at 57° N compared with satellite instruments
- 2012
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 5:5, s. 2827-2841
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of mesospheric carbon monoxide, CO, provide important information about the dynamics in the mesosphere region since CO has a long lifetime at these altitudes. Ground-based measurements of mesospheric CO made at the Onsala Space Observatory, OSO, (57 °N, 12° E) are presented. The dataset covers the period 2002-2008 and is hence uniquely long for ground-based observations. The simple and stable 115 GHz frequency-switched radiometer, calibration method, retrieval procedure and error characterization are described. A comparison between our measurements and co-located CO measurements from the satellite sensors ACE-FTS on Scisat (v2.2), MLS on Aura (v3-3), MIPAS on Envisat (V3O-CO-12 + 13 and V4O-CO-200) and SMR on Odin (v225 and v021) is carried out. Our instrument, OSO, and the four satellite instruments show the same general variation of the vertical distribution of mesospheric CO in both the annual cycle and in shorter time period events, with high CO mixing ratios during winter and very low amounts during summer in the observed 55-100 km altitude range. During 2004-2008 the agreement of the OSO instrument and the satellite sensors ACE-FTS, MLS and MIPAS (200) is good in the altitude range 55-70 km. Above 70 km, OSO shows up to 25% higher CO column values compared to both ACE and MLS. For the time period 2002-2004, CO from MIPAS (12 + 13) is up to 50% lower than OSO between 55 and 70 km. Mesospheric CO from the two versions of SMR deviates up to ±65% when compared to OSO, but the analysis is based on only a few co-locations. © 2012 Author(s).
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| 6. |
- Jégou, F., et al.
(författare)
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Validation of Odin/SMR limb observations of ozone, comparisons with OSIRIS, POAM III, ground-based and balloon-borne intruments
- 2008
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8:13, s. 3385-3409
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Tidskriftsartikel (refereegranskat)abstract
- The Odin satellite carries two instruments capable of determining stratospheric ozone profiles by limb sounding: the Sub-Millimetre Radiometer (SMR) and the UV-visible spectrograph of the OSIRIS (Optical Spectrograph and InfraRed Imager System) instrument. A large number of ozone profiles measurements were performed during six years from November 2001 to present. This ozone dataset is here used to make quantitative comparisons with satellite measurements in order to assess the quality of the Odin/SMR ozone measurements. In a first step, we compare Swedish SMR retrievals version 2.1, French SMR ozone retrievals version 222 (both from the 501.8 GHz band), and the OSIRIS retrievals version 3.0, with the operational version 4.0 ozone product from POAM III (Polar Ozone Atmospheric Measurement). In a second step, we refine the Odin/SMR validation by comparisons with ground-based instruments and balloon-borne observations. We use observations carried out within the framework of the Network for Detection of Atmospheric Composition Change (NDACC) and balloon flight missions conducted by the Canadian Space Agency (CSA), the Laboratoire de Physique et de Chimie de l\'{}Environnement (LPCE, Orléans, France), and the Service d'Aéronomie (SA, Paris, France). Coincidence criteria were 5° in latitude×10° in longitude, and 5 h in time in Odin/POAM III comparisons, 12 h in Odin/NDACC comparisons, and 72 h in Odin/balloons comparisons. An agreement is found with the POAM III experiment (10–60 km) within −0.3±0.2 ppmv (bias±standard deviation) for SMR (v222, v2.1) and within −0.5±0.2 ppmv for OSIRIS (v3.0). Odin ozone mixing ratio products are systematically slightly lower than the POAM III data and show an ozone maximum lower by 1–5 km in altitude. The comparisons with the NDACC data (10–34 km for ozonesonde, 10–50 km for lidar, 10–60 for microwave instruments) yield a good agreement within −0.15±0.3 ppmv for the SMR data and −0.3±0.3 ppmv for the OSIRIS data. Finally the comparisons with instruments on large balloons (10–31 km) show a good agreement, within −0.7±1 ppmv. The official SMR v2.1 dataset is consistent in all altitude ranges with POAM III, NDACC and large balloon-borne instruments measurements. In the SMR v2.1 data, no different systematic error has been found in the 0–35km range in comparison with the 35–60 km range. The same feature has been highlighted in both hemispheres in SMR v2.1/POAM III intercomparisons, and no latitudinal dependence has been revealed in SMR v2.1/NDACC intercomparisons.
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| 7. |
- Jones, Ashley, 1977, et al.
(författare)
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Evolution of stratospheric ozone and water vapour time series studied with satellite measurements
- 2009
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 9, s. 6055-6075
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Tidskriftsartikel (refereegranskat)abstract
- The long term evolution of stratospheric ozone and water vapour has been investigated by extending satellite time series to April 2008. For ozone, we examine monthly average ozone values from various satellite data sets for nine latitude and altitude bins covering 60° S to 60° N and 20–45 km and covering the time period of 1979–2008. Data are from the Stratospheric Aerosol and Gas Experiment (SAGE I+II), the HALogen Occultation Experiment (HALOE), the Solar BackscatterUltraViolet-2 (SBUV/2) instrument, the Sub-Millimetre Radiometer (SMR), the Optical Spectrograph InfraRed Imager System (OSIRIS), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartograpY (SCIAMACHY). Monthly ozone anomalies are calculated by utilising a linear regression model, which also models the solar, quasi-biennial oscillation (QBO), and seasonal cycle contributions. Individual instrument ozone anomalies are combined producing an all instrument average. Assuming a turning point of 1997 and that the all instrument average is represented by good instrumental long term stability, the largest statistically significant ozone declines (at two sigma) from 1979–1997 are seen at the mid-latitudes between 35 and 45 km, namely −7.2%±0.9%/decade in the Northern Hemisphere and −7.1%±0.9%/in the Southern Hemisphere. Furthermore, for the period 1997 to 2008 we find that the same locations show the largest ozone recovery (+1.4% and +0.8%/decade respectively) compared to other global regions, although the estimated trend model errors indicate that the trend estimates are not significantly different from a zero trend at the 2 sigma level. An all instrument average is also constructed from water vapour anomalies during 1991–2008, using the SAGE II, HALOE, SMR, and the Microwave Limb Sounder (Aura/MLS) measurements. We report that the decrease in water vapour values after 2001 slows down around 2004–2005 in the lower tropical stratosphere (20–25 km) and has even shown signs of increasing until present. We show that a similar correlation is also seen with the temperature measured at 100 hPa during this same period.
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| 8. |
- Jones, Ashley, 1977, et al.
(författare)
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Intercomparison of Odin/SMR Ozone measurements with MIPAS and balloon sonde data
- 2007
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Ingår i: Canadian Journal of Physics. ; 85:11, s. 1111-1123
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Tidskriftsartikel (refereegranskat)abstract
- The Sub-Millimetre Radiometer (SMR) on board Odin measures various important atmospheric species, including stratospheric ozone. In this study we compare the three versions (v1.2, v2.0 and v2.1) of level 2 Odin/SMR global stratospheric ozone data to coincident level 2 MIPAS V4.61 and balloon sonde stratospheric ozone data during 2003. The most current product from Odin/SMR (at time of writing), the v2.1, showed the smallest systematic differences when compared to coincident MIPAS and sonde data. Between 17 and 55 km, v2.1 values agreed with MIPAS within 10% (a maximum of 0.42 ppmv), while comparisons to sonde measurements showed an agreement of typically 5-10% between 22 and 35 km (less than 0.5 ppmv below 33 km). Tropical latitudes below 35 km preseneted the largest absolute systematic differences between v2.1 and sonde coincidences, where Odin/SMR was systematically lower by ~0.9 ppmv (more than 10% difference) at approximately 30 km. Comparisons concerning the previous two Odin/SMR versions showed much larger systematic differences, especially at the higher and lower stratospheric altitudes. The main conclusion here is that we suggest that v2.1 of Odin/SMR ozone data should be used for scientific studies.
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| 9. |
- Khosrawi, F., et al.
(författare)
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The SPARC water vapour assessment II: Comparison of stratospheric and lower mesospheric water vapour time series observed from satellites
- 2018
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 11:7, s. 4435-4463
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Tidskriftsartikel (refereegranskat)abstract
- Time series of stratospheric and lower mesospheric water vapour using 33 data sets from 15 different satellite instruments were compared in the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapour assessment (WAVAS-II). This comparison aimed to provide a comprehensive overview of the typical uncertainties in the observational database that can be considered in the future in observational and modelling studies, e.g addressing stratospheric water vapour trends. The time series comparisons are presented for the three latitude bands, the Antarctic (80°-70°S), the tropics (15°S-15°N) and the Northern Hemisphere mid-latitudes (50°-60°N) at four different altitudes (0.1, 3, 10 and 80hPa) covering the stratosphere and lower mesosphere. The combined temporal coverage of observations from the 15 satellite instruments allowed the consideration of the time period 1986-2014. In addition to the qualitative comparison of the time series, the agreement of the data sets is assessed quantitatively in the form of the spread (i.e. the difference between the maximum and minimum volume mixing ratios among the data sets), the (Pearson) correlation coefficient and the drift (i.e. linear changes of the difference between time series over time). Generally, good agreement between the time series was found in the middle stratosphere while larger differences were found in the lower mesosphere and near the tropopause. Concerning the latitude bands, the largest differences were found in the Antarctic while the best agreement was found for the tropics. From our assessment we find that most data sets can be considered in future observational and modelling studies, e.g. addressing stratospheric and lower mesospheric water vapour variability and trends, if data set specific characteristics (e.g. drift) and restrictions (e.g. temporal and spatial coverage) are taken into account.
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| 10. |
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