INTERPRETING SATELLITE OBSERVATIONS OF ATMOSPHERIC COMPOSITION Spring 2010 Class Objectives: 1.Familiarize ourselves with the basic techniques and measurements of composition made from space (Lectures) 2.Learn to analyze and critically evaluate satellite data products (Labs) Pre-requisites: 1.Atmospheric Radiation (ATS 622 or equivalent) 2.Programming experience (assistance from Colette will be limited to IDL) Schedule: Lectures (ACRC 212b): Mondays 2-2:50pm Lab (ERC 210): Wednesday 2-4pm (lab booked until 5pm) Extra Lab time (ERC 210): Fridays 1-3pm

OBSERVATION PLATFORMS FOR ATMOSPHERIC COMPOSITION SURFACE IN SITU SONDES, SURF.-BASED REMOTE AIRCRAFTSATELLITES Horizontal coverage --++ Vertical range -+~ (up to ~20 km) ~ (interferences) Vertical resolution none ++- Temporal coverage ++-~ (polar = daily) Chemical detail +-+- Cost ++~-

STRATOSPHERIC OZONE HAS BEEN MEASURED FROM SPACE SINCE 1979 Method: UV solar backscatter (absorption spectroscopy*) Scattering by Earth surface and atmosphere  Ozone layer  Last Monday’s ozone layer… Notice the Antarctic ozone hole *Technique originally applied to ground-based The satellite era for composition began with Nimbus 7 (launched Oct 1978) which carried LIMS, SAMS, SAMII, SBUV/TOMS (and others)

ATMOSPHERIC COMPOSITION RESEARCH IS NOW MORE DIRECTED TOWARD THE TROPOSPHERE Tropopause Stratopause Stratosphere Troposphere Ozone layer Mesosphere …but tropospheric composition measurements from space are difficult: optical interferences from water vapor, clouds, aerosols, surface, ozone layer Air quality, climate change, ecosystem issues

WHY OBSERVE TROPOSPHERIC COMPOSITION FROM SPACE? Monitoring and forecasting of air quality: ozone, aerosols Long-range transport of pollution Monitoring of sources: pollution and greenhouse gases solar backscatter thermal emission solar occultation lidar FOUR OBSERVATION METHODS: Global/continuous measurement capability important for range of issues: Radiative climate forcing

TROPOSPHERIC COMPOSITION FROM SPACE Platform multipleERS-2ADEOSTerraEnvisatAquaSpace station SCISA T-1 AuraMetOp- A Sensor TOMSAVHRR/ SeaWIFS GOMEIMGMOPITTMODIS/ MISR SCIAMA CHY MIPAS * AIRSSAGE-3ACE- FTS* TESOMIMLS*HIRDLS*CALIPSOIASI Launch O3O3 XXXXXXXXXX CO XXXXXXXX CO 2 XXXX NO XX NO 2 XXXXX HNO 3 XXXX CH 4 XXXX HCHO XXX CHOCHO XX SO 2 XXXX BrO XXX CH 3 CN X HCOOH X CH 3 OH X NH 3 XX aerosol XXXXXXX * Only in the UT

THERMAL EMISSION MEASUREMENTS (IR,  wave) EARTH SURFACE I (T o ) Absorbing gas ToTo T1T1  I (T 1 ) LIMB VIEW NADIR VIEW Examples: MLS, IMG, MOPITT, MIPAS, TES, HIRDLS, IASI Pros: versatility (many species) small field of view (nadir) vertical profiling Cons: low S/N in lower troposphere water vapor interferences

SOLAR BACKSCATTER MEASUREMENTS (UV to near-IR) absorption wavelength   Scattering by Earth surface and by atmosphere Examples: TOMS, GOME, SCIAMACHY, MODIS, MISR, OMI, OCO Pros: sensitivity to lower troposphere small field of view (nadir) Cons: Daytime only Column only Interference from stratosphere concentration Retrieved column in scattering atmosphere depends on vertical profile; need chemical transport and radiative transfer models   z

OCCULTATION MEASUREMENTS (UV to near-IR) EARTH “satellite sunrise” Tangent point; retrieve vertical profile of concentrations Examples: SAGE, POAM, GOMOS Pros: large signal/noise vertical profiling Cons: sparse data, limited coverage upper troposphere only low horizontal resolution

LIDAR MEASUREMENTS (UV to near-IR) EARTH SURFACE backscatter by atmosphere Laser pulse Examples: LITE, GLAS, CALIPSO Intensity of return vs. time lag measures vertical profile Pros: High vertical resolution Cons: Aerosols only (so far) Limited coverage

GETTING STARTED WITH IDL & ENS SERVERS 1.Get ENS userid 2.Log on to ENS servers (either from ERC classroom or remotely using ssh & Xming or some other configuration) Servers: linux.engr.colostate.edu lcompute.engr.colostate.edu 3.Set up.Xdefaults and.cshrc files in home directory to your preferences (default option: copy those in ~heald/), including PATH information for IDL. 4.source.cshrc to refresh 5.Set up IDL  copy over ~heald/IDL into your home directory (GAMAP routines, and idl_startup.pro information) 6.At the prompt anywhere type ‘idl’ to get started! 7.See examples of IDL code in ~heald/ATS681/idl_examples/