| 1. |
- Jones, Ashley, 1977, et al.
(författare)
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Analyzing the applications of an assimilation model as a method for validation of satellite data
- 2007
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D17101
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Tidskriftsartikel (refereegranskat)abstract
- An analysis was performed to illustrate that data assimilation is an appropriate method for validation of satellite measurements when very few coincidences are available between satellite measurements and balloon sondes. Results showed that the mean differences between the Isentropic Assimilation model for StratospheriC Ozone (IASCO) model ozone profiles and co-located ozone sondes shared systematic differences similar to those obtained from co-located MIPAS and ozone sonde coincidences. The spatial and temporal constraints of 12 hours and 800 km produced the optimal number of MIPAS/sonde matches for a statistical analysis. The largest residual between the IASCO/sonde mean difference and MIPAS/sonde mean difference, using these constraints, was less than 0.25 ppmv, between potential temperature levels of 425-975 K. By using the assimilation model coincidences, we also conclude that the maximum time/distance constraint sizes that can be used when obtaining matches between satellite measurements and in-situ measurements should be no more than 24 hours and a maximum of 1500-2000 km. However, local conditions such as the presence of a dynamical feature, for example the edge of the polar vortex, may of course greatly restrict these limits.
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| 2. |
- 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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| 3. |
- RÖSEVALL, JOHN, 1977, et al.
(författare)
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A study of polar ozone depletion based on sequential assimilation of satellite data from the ENVISAT/MIPAS and Odin/SMR instruments
- 2007
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Ingår i: Atmospheric Chemistry and Physics. - 1680-7316 .- 1680-7324. ; 7:3, s. 899-911
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study is to demonstrate how polar ozone depletion can be mapped and quantified by assimilating ozone data from satellites into the wind driven transport model DIAMOND, (Dynamical Isentropic Assimilation Model for OdiN Data). By assimilating a large set of satellite data into a transport model, ozone fields can be built up that are less noisy than the individual satellite ozone profiles. The transported fields can subsequently be compared to later sets of incoming satellite data so that the rates and geographical distribution of ozone depletion can be determined. By tracing the amounts of solar irradiation received by different air parcels in a transport model it is furthermore possible to study the photolytic reactions that destroy ozone. In this study, destruction of ozone that took place in the Antarctic winter of 2003 and in the Arctic winter of 2002/2003 have been examined by assimilating ozone data from the ENVISAT/MIPAS and Odin/SMR satellite-instruments. Large scale depletion of ozone was observed in the Antarctic polar vortex of 2003 when sunlight returned after the polar night. By mid October ENVISAT/MIPAS data indicate vortex ozone depletion in the ranges 80–100% and 70–90% on the 425 and 475 K potential temperature levels respectively while the Odin/SMR data indicates depletion in the ranges 70–90% and 50–70%. The discrepancy between the two instruments has been attributed to systematic errors in the Odin/SMR data. Assimilated fields of ENVISAT/MIPAS data indicate ozone depletion in the range 10–20% on the 475 K potential temperature level, (~19 km altitude), in the central regions of the 2002/2003 Arctic polar vortex. Assimilated fields of Odin/SMR data on the other hand indicate ozone depletion in the range 20–30%.
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