1. CHEM Science Team March 2000 Cloud processes near the tropopause HIRDLS will measure cloud top altitude and aerosol concentrations: the limb view gives high sensitivity; geometry used to determine altitude with fine resolution (200 m step size; 1 km IFOV) May benefit from formation flying partners Aqua, PICASSO-CENA and CloudSat to obtain very comprehensive near-simultaneous cloud measurements and for cross-validation. [STS047-54-018, 20 Sep 1992, 15.5 S, 158.5 E] Silhouette of several thunderstorms with cirrus anvil tops spreading out against the tropopause, and Pinatubo aerosol layers appearing blue above.

2. CHEM Science Team March 2000 Frequency of cirrus measured by HALOE Relative frequency of occurrence of larger extinction values measured at 3.46 micron by the UARS HALOE instrument for 1993-1998. [ S.Massie et al, submitted to J. Geophys. Res., 1999 ]

3. CHEM Science Team March 2000 Frequency of cirrus measured by HALOE Relative frequency of occurrence of larger extinction values measured at 3.46 micron by the UARS HALOE instrument for 1993-1998. [ S.Massie et al, submitted to J. Geophys. Res., 1999]

4. CHEM Science Team March 2000 Variation of limb extinction Frequency of limb extinction at 3.46 micron and 121 hPa tangent pressure measured by HALOE for different years. Data are for the Indian Ocean to the Eastern Pacific between 30 o N and 30 o S. [S.Massie et al, ‘The Effect of the 1997 El Nino on the Distribution of Upper Tropospheric Cirrus’, submitted to J. Geophys. Res., 1999]

5. CHEM Science Team March 2000 Radiative transfer studies HIRDLS will measure the radiation emitted in multiple spectral passbands up to the thermosphere Important for validating radiative transfer theory and undertaking basic research into radiative transfer

6. CHEM Science Team March 2000 (Day-Night )/Night radiance difference measured by CRISTA in 1490-1560 cm -1 spectral region Daytime enhancement is due to a combination of H 2 O non- LTE emission and tidal activity increasing daytime temperature Radiative transfer studies [Figure from David Edwards]

7. CHEM Science Team March 2000 Acquisition of atmospheric data in an extreme state Stratospheric chlorine levels are expected to peak during the EOS-Chem mission. EOS-Chem data will be valuable for centuries into the future as tests of model behaviour in this extreme high-chlorine state. Changes in ozone levels as chlorine declines and stratospheric cooling accelerates will provide critical tests of model behaviour and their ability to predict.

8. CHEM Science Team March 2000 Growth of stratospheric chlorine according to various scenarios (from Joe Waters) Stratospheric Chlorine

9. CHEM Science Team March 2000 HIRDLS Scientific Objectives Understand stratosphere-troposphere exchange of radiatively and chemically active constituents (including aerosols) down to small spatial scales Understand chemical processing, transports and mixing in the upper troposphere/lowermost stratosphere/lower overworld Understand budgets of quantities (momentum, energy, heat and potential vorticity) in the middle atmosphere that control stratosphere-troposphere exchange Determine upper tropospheric composition (with high vertical resolution) Provide data to improve and validate small scales in models Measure global distributions of aerosols and PSC’s and interannual variations

10. CHEM Science Team March 2000 Major HIRDLS Emphases Small scale dynamics and transports Troposphere - stratosphere exchange Polar vortex filamentation Tropical barrier leakage Upper troposphere - lower stratosphere chemistry O 3, H 2 O, CFC 11, CFC 12, HNO 3, CH 4, N 2 O Aerosol amounts, distributions & properties Trends & changes Trends of 10 radiativity & chemically active species, T, PSCs Continuation of LIMS, SAMS, UARS Gravity wave distributions Sources & distributions of gravity waves, and their roles in atmospheric dynamics

11. CHEM Science Team March 2000 Summary of Measurement Requirements Temperature<50 km 0.4 K precision 1 K absolute >50 km 1 K precision 2 K absolute ConstituentsO 3, H 2 O, CH 4, H 2 O, HNO 3, NO 2, N 2 O 5, 1-5% precision ClONO 2, CF 2 Cl 2, CFCl 3, Aerosol 5-10% absolute Geopotential height gradient 20 metres/500 km (vertical/horizontal) (Equivalent 60 o N geostrophic wind) (3 m s -1 ) Coverage: Horizontal - global 90 o S to 90 o N (must include polar night) Vertical - upper troposphere to mesopause (8-80 km) Temporal - long-term, continuous (5 years unbroken) Resolution: Horizontal - profile spacing of 5 o latitude x 5 o longitude (approx 500 km) Vertical - 1-1.25 km Temporal - complete field in 12 hours

12. CHEM Science Team March 2000 HIRDLS Cleanroom

13. CHEM Science Team March 2000 Collimator/monochromator calibration equipment

14. CHEM Science Team March 2000 Monochromator turret Seismic isolator Clean room and vacuum chamber Chamber optical bench HIRDLS Calibration Facility