Odin-OSIRIS: A Summary of the Results from the Past Eleven Years

Transcription

1 Odin-OSIRIS: A Summary of the Results from the Past Eleven Years ESA ATMOS 12 June 18, 12 Bruges, Brussels

2 : Year Eleven of a Two Year Mission ESA ATMOS 12 June 18, 12 Bruges, Brussels

3 OSIRIS Designed and built by ROUTES Inc. in Ottawa Original PI was Ted Llewellyn from the University of Saskatchewan Started in 1993 and was ready in 1999 Integrated onto the Odin spacecraft in

4 Odin Designed and built by SSC in Sweden Project is an international venture that also includes Finland and France Includes a submillimeter radiometer that was also designed for astronomy Launched in 1 out of Russia

5 Odin Launch February, 1

6 The Odin Orbit OSIRIS sun-synchronous orbit sun-synchronous near-terminator 98 degree inclination 18h ascending node 6h descending node 96 minute period 6 km altitude latitude (degrees) ascending node local time (hours)

7 The Atmosphere as Seen from Odin Bright Dim.5 º The sky is blue The fade to black Radiance (photons/s/cm 2 /nm/sterad) 7 x km km km 4 km Wavelength (nm)

8 Limb Scattering A measurement of the intensity of sunlight scattered from the atmosphere Scattering from Earth s surface Multiple Scattering Low Earth Orbit (about 6 km) Earth Radius (about 637 km) Radiance (photons/s/cm 2 /nm/sterad) 7 x km km km 4 km Wavelength (nm)

9 Tangent Altitude (km) Optical Spectrograph and Infra-Red Imager System (OSIRIS) Limb Radiance (photons/s/cm 2 /nm/sterad) Wavelength (nm) x ) Optical Spectrograph Single line of sight along satellite track Narrow horizontal slit (1 arc minute) Grating spectrograh nm, 1 nm resolution Measures spectrum of scattered sunlight Tangent altitudes to 1 km Odin moves to point OSIRIS 2) Infrared Imager Three channel filtered vertical imager 1.26 and 1.27 micron Singlet Delta O micron OH Meinel Radiance (photons/s/cm 2 /nm/sterad) 7 x km km km 4 km Wavelength (nm) O 3 Dust NO NO 2 Forest Fires BrO Noctilucent Clouds The Aurora OH Sodium Sulphate Aerosol Subvisual Cirrus

10 Ozone Ozone Limb Radiance (photons/s/cm 2 /nm/sterad) x Tangent Altitude (km) Wavelength (nm)

11 OSIRIS Ozone OSIRIS ozone is used in four international data initiatives SPIN SPARC Data Initiative SI 2 N ozone_cci Strengths of the OSIRIS ozone data product Overall accuracy at all altitudes Accuracy in the UTLS Stability over time

12 Ozone: Limb Scatter Signature Ozone Retrieval at Optical Wavelengths UV wavelengths (Hartley-Huggins bands) Visible wavelengths (Chappuis bands) Limb Signature of Ozone Minimum altitude probed by a line of sight identified by a knee in the radiance profile (optically thick) Ozone Cross Section (cm 2 ) Hartley-Huggins Band Chappuis Band Altitude (km) nm 2 nm 6 nm 9 nm 315 nm 331 nm 351 nm nm 62 nm 679 nm Wavelength (nm) Limb Radiance (photons/s/cm 2 /nm/sterad) The use of normalized wavelength pairs and triplets make the ozone retrieval process self calibrating so instrument stability is less of an issue

13 Ozone: Odin-OSIRIS Comparison SAGE II Ozone is the Gold Standard (Langley Team) Four years of overlap with OSIRIS mission Coincidence criteria: km, 2 hours 196 measurement events 8 6 Latitude (degrees) Longitude (degrees)

14 Ozone: OSIRIS - SAGE II Comparison 6 5 OSIRIS-MART SAGE II Latitude = 44.1 o 6 5 OSIRIS-MART SAGE II Latitude = o 6 5 OSIRIS-MART SAGE II Latitude = o 6 5 OSIRIS-MART SAGE II Latitude = o Altitude (km) O x (cm -3 ) O x (cm -3 ) O x (cm -3 ) O x (cm -3 ) Individual profiles show main vertical structure is well captured, even at lowest altitudes Statistics on the entire 196 profile set Mean bias of <2% from 18-5 km Standard dev ~5% from -5 km Altitude (km) Mean of Percent Difference (OSIRIS-SAGE II) Standard Deviation of Percent Difference

15 Ozone: OSIRIS - SAGE II Comparison Almost 5 coincident profiles compared with less that 2% bias between and 45 km. The coincident criteria is +/- 24 hours, +/- 1 degree latitude and +/- 1 km.

16 The same set of coincidences filtered by Solar Zenith Angle, OSIRIS Optics Temperature and Latitude. There seems to be a small high bias near 22.5 km, when OSIRIS gets cold it appears the optics defocus or it may be spacecraft twisting such that the pointing information is off. Equatorial scan show biases at altitudes up to 23 km.

17 The Stability of the OSIRIS Ozone Work by Daan Hubert and presented at meetings like the SI 2 N meeting in Columbia shows no significant drift in OSIRIS ozone data when compared with lidars and sondes. These lidar results are from one station but are consistent with entire analysis

18 OSIRIS Ozone These low altitude sonde comparisons are from the same work by Daan What may not be obvious from this figure is that the OSIRIS biases with respect to the sondes are very low in the UTLS region Other work by independent groups is also demonstrating the utility of the OSIRIS data set for study of the UTLS

19 OSIRIS Ozone O 3 Number Density 6 x km Altitude O 3 Time Series for 4 o to 45 o Latitude at Selected Altitudes OSIRIS SAGE II x km Altitude Date A sample of the OSIRIS time series as compared with SAGE II Overall agreement is remarkable when it should be

20 Odin-OSIRIS Ozone Trend Analysis Done at Environment Canada Environment Canada scientists led by Chris McLinden are using the OSIRIS ozone data product (1-9) to extend the SAGE I and II time series Together with SBUV and the various SBUV2 instruments, a homogeneous monthly, zonal-mean data set is being constructed that may be suitable for use in trend studies. The precision and stability of the OSIRIS data make it a useful resource for extending the SAGE data record from 5 to the present SBUV+SAGE+OSIRIS Ozone Anomalies (48 o N, 43 km).5 Anomaly Monthly Mean EESC Regression Year

21 Sulphate Aerosols Sulphate Aerosols Limb Radiance (photons/s/cm 2 /nm/sterad) x Tangent Altitude (km) Wavelength (nm)

22 OSIRIS Aerosol OSIRIS aerosol is used in at least three international data initiatives SPIN SPARC Data Initiative aerosol_cci

23 The OSIRIS Aerosol Retrieval Limb Radiance Typical limb spectrum at 22 km tangent altitude calculated with the SASKTRAN Radiative Transfer Model Modeled Limb Radiance (1 13 photons/s/cm 2 /nm/sterad) 2.5 clean atmosphere 2 background aerosol The Measurement Vector I( λ 2) = I y log log I( λ1 ) I I (λ) R R R ( λ 2) ( λ1 ) Model with no aerosol Effectively a measure of the residual scattering Wavelength (nm) I ( λ 1 ) I λ ) ( 2 Assume typical sulphate aerosol particle size distribution and composition Use Mie scattering cross sections and phase functions Retrieve number density of assumed particles convert to extinction at 75 nm

24 Comparison with SAGE III 35 SAGE III Lat: Lon: t = 3.2h OSIRIS Lat: -5.3 Lon: t = 3.2h SAGE III Lat: Lon: -1.5 t = 7.1h OSIRIS Lat: Lon: -1.6 t = 7.1h Altitude (km) Altitude (km) SAGE III Lat: 75.5 Lon: t = 1.7h OSIRIS Lat: 75.8 Lon: -.9 t = 1.7h SAGE III Lat: Lon: t = 7.8h OSIRIS Lat: Lon: -41. t = 7.8h SAGE III (V4) 755 nm Aerosol Extinction OSIRIS 75 nm Aerosol Extinction Tight coincident scan comparison 1 latitude, 2.5 longitude, 6 hours Good agreement of magnitude and vertical features nm Extinction (km -1 x ) nm Extinction (km -1 ) x 1-4

25 Comparison with SAGE III Zonal Average Time Series Degrees 9 6 Latitude (N) OSIRIS SZA All SAGE II data Some OSIRIS data Biases less than 1 % in the Junge layer SAGE III Altitude (km) 1 OSIRIS 1 Altitude (km) Rel Diff 1 Altitude (km) Jun2 Jun3 Jun4 Jun5 Time

26 Sulphate Aerosols: Results for One Month Extinction at 22 km in October, 1

27 Sulphate Aerosols: Total Optical Depth Movie

28 Sub-visual Cirrus

29 The culmination of a recent PhD project We can now model the spectral signature of subvisual cirrus clouds The parameters were retrieved from the OSIRIS measurements and the forward model successfully simulates observations This will help with biases in the ozone retrieval at altitudes above and below the tropopause

30 Subvisual Cirrus Cloud Database: Truitt Wiensz, University of Saskatchewan Atmospheric Limb Workshop We have a database of occurrences and we are in the process of retrieving cloud properties such as vertical and optical thickness

31 Work to be Done Ozone Implement subvisual cirrus cloud retrieval to mitigate 22 km bias Implement time dependent point spread function to mitigate low temperature bias Fully characterize biases with respect to SAGE II, ENVISAT instruments and ground based instruments Attempt merging of datasets Aerosol Implement new particle size retrievals Attempt to validate new results

32 Recent Highlights

33 Odin-OSIRIS View of the 11 Northern Hemsiphere Ozone Hole The Arctic atmosphere is getting colder every year and with this comes ozone holes OSIRIS measurements inside and outside the hole

34 Odin-OSIRIS View of the 11 Northern Hemsiphere Ozone Hole Time evolution of the ozone hole as measured by OSIRIS

35 Stratospheric Aerosol Long Term Trends Recent results in GRL (Hofmann et al., Aug 9) show ground based measurements of anomalous increase in stratospheric aerosol background layer deseasonalized trend OSIRIS retrievals (optical depth from -25 km) for all scans since 2 within 7 km of Mauna Loa 1-3 OSIRIS Stratospheric Aerosol Over Mauna Loa Aerosol Optical Depth ( to 25 km) 1-4 5% per year Year Soufriere Hills Montserrat 16 N, 62 W Kasatochi Aleutian Arc 52 N, 175 W

36 4 35 OSIRIS Stratospheric Aerosol Time Series 5 N to 8 N Altitude (km) S to N Altitude (km) Figure from Vernier et al, GRL, S to 8 S Altitude (km)

37 The Up-To-Date OSIRIS Stratospheric AOD Record Mt. Manam Soufriere Hills Kasatochi Sarychev Peak Mt. Merapi Nabro Latitude Time nm Stratospheric Aerosol Optical Depth x 1-3

38 OSIRIS Measurements of the Nabro Aerosol Cloud 25 1-Jun Jun Jun-11 Altitude (km) 15 Day 12 June 25 Altitude (km) Jul Jul Jul Aug-11 5-Sep Sep-11 Day 18 July 1 Altitude (km) Latitude Latitude Latitude Day 24 July 7 Day 31 July 14 Day 48 July 75nm Extinction Ratio The Nabro stratovolcano in Eritrea, Northeastern Africa, erupted on June 13, 11, injecting approximately 1.3 Tg SO 2 to altitudes of 9 to 14 km in the upper troposphere This resulted in a large aerosol enhancement in the stratosphere. The SO 2 was lofted into the lower stratosphere by deep convection and the circulation associated with the Asian monsoon To impact climate, volcanic eruptions need not be strong enough to inject sulfur directly to the stratosphere.

39 Summary has collected data for over a decade We have learned much about the retrieval of ozone etc. from limb scattered sunlight We hope for many more years of OSIRIS results to add to the existing data sets Thank You!