E.J. Llewellyn 1 , R.L Ga0nger 1 , W.F.J. Evans 2,3 , I.C. McDade 3,4 , P.E. Sheese 1,5 , A.E. Bourassa 1 , L. Rieger 1 , N.D. Lloyd 1 and D.A. Degenstein 1 1 ISAS, University of Saskatchewan, Saskatoon, SK 2 NWRA, Redmond, WA, USA 3 CRESS, York University, Toronto, ON 4 ESSE, York University, Toronto, ON 5 Physics Dept, University of Toronto, Toronto, ON Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb
N.D. Lloyd1 and D.A. Degenstein1 1 ISAS, University of Saskatchewan, Saskatoon, SK
2 NWRA, Redmond, WA, USA 3 CRESS, York University, Toronto, ON 4 ESSE, York University, Toronto, ON
5 Physics Dept, University of Toronto, Toronto, ON
Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb
Nadir Observa,ons in the Limb -‐ OSIRIS Measurements that do not appear in a grant applica,on
E.J. Llewellyn1, P.E. Sheese2, R.L. GaGnger1, L. Rieger1, A.E. Bourassa1, N.D. Lloyd1, I.C. McDade3, W.F.J. Evans3,4 and D.A. Degenstein1
1 ISAS, University of Saskatchewan, Saskatoon, SK S7N 5E2 2 Physics Department, University of Toronto, Toronto, ON M5S 1A7 3 CRESS, York University, Toronto, ON M3J 1P3 4 NWRA, Redmond, WA 98052
This slide show the easy way to get errors in limb profiles and emission altitudes.
Figure 10. The first tomographic retrievals for the nighttime data sets that are shown in Figure 5.
• Odin/OSIRIS is in a 0600-‐1800 orbit (frequently called a terminator orbit but in reality is fully sunlit condi]ons in summer).
• Thus observa]ons of PMC’s in the limb will have the clouds illuminated by both direct sunlight and sca`ered light from the earth below.
• This upwelling radia]on will necessarily include the signatures of species in the lower atmosphere. Hence observing the PMC spectral signature provides a nadir observa]on. Remember the contribu]on from the upwelling radia]on can be up to 3 ]mes as bright as the direct sunlight contribu]on.
• Obviously extrac]ng this PMC signature means that we must subtract the true solar spectrum signature; this is quite straighdorward.
• We then apply a DOAS technique to the remaining sca`ered signal and extract the column concentra]on of species below the cloud. We do not require a detailed knowledge of the light path as we can ra]o the derived concentra]on to the ozone column.
• This technique has been used to derive the column concentr]ons reported here.
Limb Observa,ons as seen by OSIRIS and SaskTran
The measured radiation along each line of sight is made up of a number of components. A model must include each of these components accurately if the observations are to be inverted.
Typical vertical profiles of OS limb radiance intensity at 372.7 nm in the absence of PMC
(thin curves) and in the presence of PMC (thick curve with diamonds, notice the enhancement).
PMC Observa]ons with OSIRIS
Optical spectrograph Limb Scan from 10 – 60 km. OSIRIS observations near 80 N, 0 W, July 2001. Missing region is at the position of the order sorter.
A-‐Band goes from absorp]on into emission with increasing tangent al]tude
Examples of the cold temperatures at the summer mesopause. (a) Frequency of retrieved mesospheric temperatures in January and July of 2008. (b) A retrieved temperature profile of 16 January 2008, dashed lines indicate total uncertainty based on retrieved S-values. (c) The fit between the 16 January 2008 VER spectrum at 92 km and the model spectrum at 91 K.
3-year composites of daytime [O] at 93 km as determined by OSIRIS (left) and predicted by the MSIS model (right).
All values correspond to a local time of ~19:00, latitudinal bins represent 10° average and daily bins represent 30-day average.
Limb Observa,ons as seen by OSIRIS and SaskTran
The measured radiation along each line of sight is made up of a number of components. A model must include each of these components accurately if the observations are to be inverted.
Troposphere: SaskTran Model Results and OSIRIS Observa,ons
H2O and O2
• Most PMC observa]ons to date have looked at the brightness of the cloud.
• The possibility of looking at the spectrum of the PMC sca`ered radia]on from space is essen]ally new. There are observa]ons of the spectrum of radia]on transmi`ed by the clouds.
• If the spectrum is measured then it provides informa]on on the absorbing species along the line-‐of-‐sight of the sca`ered radia]on.
• Low al]tude limb observa]ons are extremely difficult due to the large op]cal depths encountered.
• Spectral observa]ons of PMC sca`erd light affords a novel way making uv nadir observa]ons in the limb.
ACE-‐FTS average NO density from 85 to 100 km versus NO average density from 85 to 100 km derived from OSIRIS NO2 con]nuum and [O] observa]ons.
Data are for Antarc]c winter observa]ons from 2004 to 2007.
The 100 to 105 km tangent limb calibrated auroral spectrum observed by OSIRIS, 275 nm to 815 nm for spectra obtained on 7-‐8 January 2005. Data within the spectral range of the OSIRIS order sorter from 480 nm to 530 nm are absent. For figure clarity the synthe]c spectrum components are not included
NO and Ap correla]on
Antarctic [NO] climatologies from (a) OSIRIS, (b) ACE-FTS, and (c) SMR. All data are smoothed with a 30-day triangular filter.
This work has been supported with funds from the Canadian Space Agency, NSERC and the University of Saskatchewan.
Thank you for listening and please recognize that the problems you can study with OSIRIS are only limited by your imagina]on.
This slide show the easy way to get errors in limb profiles and emission altitudes.
Figure 10. The first tomographic retrievals for the nighttime data sets that are shown in Figure 5.
Examples of the cold temperatures at the summer mesopause. (a) Frequency of retrieved mesospheric temperatures in January and July of 2008. (b) A retrieved temperature profile of 16 January 2008, dashed lines indicate total uncertainty based on retrieved S-values. (c) The fit between the 16 January 2008 VER spectrum at 92 km and the model spectrum at 91 K.
