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HIRDLS SPARC Applications and Development Status John Gille University of Colorado and NCAR John Barnett Oxford University Alyn Lambert, David Edwards, Christopher Palmer Michael Dials, Chris Halvorson, Eric Johnson, Wayne Rudolf Ken Stone, Bob Wells, John Whitney, Douglas Woodard 1 HIRDLS Scientific Goals The primary goals of the High Resolution Dynamics Limb Sounder (HIRDLS) experiment are to acquire data with which to investigate 1) the recovery of the ozone layer following the phase-out of some halogen-containing chemicals; 2) the role of the upper troposphere and lower stratosphere (UT/LS) in climate; and 3) the chemistry of the upper troposphere. 2 Recovery of the Ozone Layer • • • • • Stratospheric chlorine is predicted to decrease as a result of the Montreal Protocol and subsequent agreements Chlorine abundances are decreasing in the troposphere, and now, in the stratosphere The recovery of the ozone layer with decreasing Cl will be complicated by the lower temperatures in the lower stratosphere, due to greenhouse effects as well as the reduction in ozone itself HIRDLS, and the Aura spacecraft, will fly during the unique period near the maximum loading of stratospheric chlorine. It will be important to acquire a record of atmospheric composition and behavior during this singular period. One of the goals of HIRDLS is to document this period in the atmosphere, and use these data to understand ozone chemistry and radiative effects in this unique period. 3 Stratospheric Chlorine A3 CH 3Br(A) HCFCs E E S C ( ppb ) 3.0 Halons CH 3CCl3 CCl4 2.0 CFCs 1.0 CH 3Br(N) CH 3Cl 1960 1980 2000 2020 2040 2060 Growth of stratospheric chlorine according to various scenarios Figure 1 4 The Role of the UT/LS in Climate • • • • The structure and behavior of the atmosphere around the tropopause are now known to be more complex than previously thought. Exchange of material between the troposphere and the stratosphere takes place not only through ascent through the tropical tropopause, but also through transports along isentropic surfaces that cross the tropopause. These transports include those of radiatively active (e.g. CO2, H2O, CH4, etc.) and chemically active (N2O, CFC11, CFC12, H2O, etc.) gases that directly or indirectly influence the earth’s radiative balance. Many of these transports are on finer scales than have been observed before. In addition, there are other features which lead to the formation of fine scale filaments. One of HIRDLS’ goals is to observe these small-scale transports and subsequent mixing, and to clarify their effects in the climate system. 5 Transport Features Observed by HIRDLS Figure 2 (from J. Holton/UGAMP) 6 Stratosphere-troposphere exchange on small scales Passive tracers on the 320 K isentrope. Coloured air is stratospheric, blank is tropospheric Figure 3 [From Appenzeller et al. [1995]] 7 UT/LS Chemistry • HIRDLS measurements will extend down into the lower stratosphere and upper troposphere when clouds are not too optically thick. • Trace species in this region are rapidly transported over long distances. • HIRDLS will obtain measurements of: O3, H2O, and HNO3, CFC11, CFC12, CH4, N20 and aerosols. • These data will greatly augment knowledge of composition and transports at these levels. 8 Summary of Measurement Requirements Temperature <50 km >50 km 0.41 KK precision absolute 1 K precision 2 K absolute Constituents O3, H2O, CH4, H2O, HNO3, NO2, N2O5, 1-5% precision ClONO2, CF2Cl2, CFCl3, Aerosol 5-10% absolute Geopotential height gradient 20 metres/500 km (vertical/horizontal) (Equivalent 60oN geostrophic wind) (3 m s-1) Coverage: Horizontal - global 90oS to 90oN (must include polar night) Vertical - upper troposphere to mesopause (8-80 km) Temporal - long-term, continuous (5 years unbroken) Resolution: Horizontal - profile spacing of 5o latitude x 5o longitude (approx 500 km) Vertical - 1-1.25 km Temporal - complete field in 12 hours The LIMB Scanning Technique Infrared radiance emitted by the earth’s atmosphere, seen at the limb, is measured as a function of relative altitude Spectral Locations of the HIRDLS Channels Figure 5 11 Examples of Calculated Radiance Profiles Channel 3 (CO 2, optically thick) 70 60 50 40 30 radiometric noise apparent tangent height, h / km 80 20 10 0 10-4 10-3 10-2 10-1 100 101 atmospheric radiance, L / W·m–2·sr–1 12 Driving Requirements on Accuracy and Precision Retrieval based on N (h). This leads to the most stringent requirements: Radiance Accuracy 1% (temperature channels 0.5%), Random noise1-12 x 10-4 Wm-2 sr-1 (channel dependent) Sample spacing Accuracy 0.25%, random error of 1 arcsec (1 ). Requirements are divided between - encoder on the scan mirror (motion relative to optical bench), and - gyroscope on the optical bench (motion of bench in inertial space). 13 HIRDLS Alternative Global Mode Sub-Tangent Point HIRDLS Boresight Tangent Point Latitudes and Longitudes in the Alternative Global Mode Figure 6 HIRDLS Instrument Consists of 9 Subsystems IN-FLIGHT CALIBRATION SUBSYSTEM (IFC) OPTICAL ITEMS AND ELECTRONICS TO ENABLE RADIOMETRIC CALIBRATION DURING FLIGHT OPERATIONS. SUN-SHIELD SUBSYSTEM (SSH) TELESCOPE SUBSYSTEM (TSS) INSTRUMENT TELESCOPE AND RELATED ELECTRONICS UNITS POWER SUBSYSTEM (PSS) PROVIDES BASIC POWER CONVERSION AND SWITCHING •UK •US DETECTOR SUBSYSTEM (DSS) MULTI-CHANNEL INFRARED RADIOMETRIC DETECTOR ARRAY AND DEWAR ASSEMBLY INSTRUMENT PROCESSING SUBSYSTEM (IPS) SIGNAL AND DATA PROCESSING TO SUPPORT MISSION SCIENCE OPERATIONS AND HOUSEKEEPING FUNCTIONS GYRO SUBSYSTEM (GSS) PROVIDES PRECISION BASE MOTION DISTURBANCE DATA STRUCTURAL THERMAL SUBSYSTEM (STH) PRIMARY STRUCTURAL SUPPORT AND ENVIRONMENTAL ENCLOSURE FOR ELECTRONIC UNITS AND TELESCOPE COOLER SUBSYSTEM (CSS) PROVIDES ACTIVE CRYO-COOLING FOR THE INSTRUMENT DETECTOR ARRAY Figure 7 15 INSTRUMENT SUBSYSTEMS - EXPLODED VIEW Fixed Sunshield (STH) Sunshield-Door (SSH) Black Body Assembly (IFC) Optical Bench Assy. with Shroud (TSS) External Connector Bulkhead Encoder Electronics Assy. (TSS) LEGEND STH SSH TSS DSS GSS CSS IFC PSS IPS Power Converter Unit (PSS) Telescope Electronics Unit (TSS) Cooler Control Unit (CSS) Space-View Aperture Assembly (SSH) Signal Processing Unit (IPS) Gyro Electronics Unit (GSS) Detector Dewar (DSS) Baseplate (STH) S-Link (CSS) Cooler Radiator Panel with Compressors & Displacer (CSS) Flexible Vacuum Enclosure (CSS) Gyro Mechanical Unit (GSS) Vibration Isolators (TSS) Black Body Electronics Unit (IFC) Inst. Processor Unit (IPS) 16 Optical Schematic Space View Port Space View Aperture Stop Space View Relay Mirror Field Stop #2 & Warm Filter Assembly Intermediate Lyot Stop Lens Assembly Ge Lens #1 Space View Field Stop Albedo Shield Secondary Mirror Telescope Subsystem Structural Thermal Subsystem Fold System Aperture Stop Out-of-Field Baffle Field Stop #1 Ge Lens #2 Chopper Radiation Trap Chopper Mechanical Unit Primary Mirror Primary Diffraction Baffle (PDB) Scan Mirror Sunshield Door "Hot Dog" Aperture In-flight Calibrator Black Body DSS Cold Filter Assembly Sunshield Door Aperture Calibrator Mirror Fixed Sunshade Figure 8 17 Figure 9 18 Figure 10 19 Structure Thermal Subsystem Status Dummy MLI on Flight Structure in MMS Clean Room Figure 11 20 HIRDLS Calibration Facility Clean room and vacuum chamber Seismic isolator Chamber optical bench Monochromator turret 21 Title: (tem_err.eps) Creator: Adobe Illustrator(R) 8.0 Preview: This EPS picture was not saved witha preview(TIFF or PICT) included init Comment: This EPS picture will print to a postscript printer but not to other types of printers 22 Title: (o3_err.eps) Creator: Adobe Illustrator(R) 8.0 Preview: This EPS picture was not saved witha preview(TIFFor PICT) included init Comment: This EPS picture will print to a postscript printer but not to other types of printers 23 Title: (h2o_err.eps) Creator: Adobe Illustrator(R) 8.0 Preview: This EPS picture was not saved witha preview(TIFFor PICT) included init Comment: This EPS picture will print to a postscript printer but not to other types of printers 24 Verification of 1 KM Resolution True Temperature Wave Retrieved Temperature Wave 0.1 true pressure, p / hPa 1 10 100 1000 -2 -1.5 -1 -0.5 0 0.5 1 temperature wave, T / K 1.5 2 25 HIRDLS CAPABILITIES 80 PRECISION MIXING RATIO TEMP (%) (K) 15 10 Altitude (km) 60 5 1. 3 .5 1 .25 40 20 TEMP HO 2 O3 NO 2 CH4 NO 2 5 NO 2 Figure 12 CFCl HNO 3 PSC Locations CF Cl 2 Aerosol Cloud 2 Tops Effects 3 ClO NO 2 26 Summary • • • HIRDLS is a powerful and flexible instrument for the global measurement from the upper troposphere into the mesosphere of Temperature, 10 trace species and aerosols New features are: – Fine spacing of measured profiles in the longitudinal direction (<500km) – High vertical resolution (<2 km vertical wavelength) – Ability to sound the upper troposphere and low stratosphere (UT/LS) regions – Measurement of many species with a range of chemical lifetimes – 5-6 year instrument life Standard data will provide long-term detailed data and important insights into: – Evolution of the ozone layer – Climate processes, especially in the tropopause region – Upper troposphere chemistry 27 Additional information on HIRDLS can be found at the HIRDLS website, http://www.eos.ucar.edu/hirdls/home.html. 28