Use or disclosure of this information may be subject to United States export control laws. For official use only. 1 UV/VIS Limb Scatter Workshop- University of Bremen OMPS Limb Profiler Retrieving Ozone from Limb Scatter Measurements Jack Larsen, Colin Seftor, Boris Petrenko, Vladimir Kondratovich Raytheon Information Technology and Scientific Services Dave Flittner University of Arizona Quinn Remund, Juan Rodriguez, Jim Leitch, Brian McComas Ball Aerospace and Technologies Corp Glen Jaross Science Systems and Applications, Inc Tom Swissler Swissler Info Tech
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OMPS Limb Profiler Retrieving Ozone from Limb Scatter Measurements
OMPS Limb Profiler Retrieving Ozone from Limb Scatter Measurements. Jack Larsen, Colin Seftor, Boris Petrenko, Vladimir Kondratovich Raytheon Information Technology and Scientific Services Dave Flittner University of Arizona Quinn Remund, Juan Rodriguez, Jim Leitch, Brian McComas - PowerPoint PPT Presentation
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Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.1
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
OMPS Limb ProfilerRetrieving Ozone from Limb Scatter Measurements
Jack Larsen, Colin Seftor, Boris Petrenko, Vladimir KondratovichRaytheon Information Technology and Scientific Services
Dave FlittnerUniversity of Arizona
Quinn Remund, Juan Rodriguez, Jim Leitch, Brian McComasBall Aerospace and Technologies Corp
Glen JarossScience Systems and Applications, Inc
Tom SwisslerSwissler Info Tech
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
tropopause - 15 km : greater of 20% and 0.1 ppmv15 - 60 km : greater of 10% and 0.1 ppmv
Measurement precision :tropopause height- 15 km : 10%15 - 50 km : 3%50 - 60 km : 10%
Long term stability : 2% over 7-year single sensor lifetimeMaximum local average revisit time : 4 days
Exceptions to EDR performance (precision and accuracy)Ozone volume mixing ratio < 0.3ppmvVolcanic aerosol loading - CCD saturation - optical depth
Provide profiles of the volumetric concentration of ozone
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
4
Limb scattering technique has improved vertical resolution over Nadir profile products
General Description - Basis for SOLSE/LORE and OMPS Limb Algorithms
By measuring the amount of scatter and absorption of solar radiation through the atmosphere at different wavelengths (e.g. UV, visible, near-infrared), profile scattering instruments can infer the vertical profiles of a number of trace constituents, including ozone
Limb scatter combines advantages of both BUV and visible limb occultation methods
– Limb viewing geometry provides good vertical resolution
– Measurements can be made throughout the sunlit portion of the orbit; not restricted by sun within FOV
Ozone Products
Profiling
UV, VIS, NIR Limb
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
5
Sensor is based on a Prism Spectrometer
Prism spectrometer provides spectral coverage from 290 nm to 1000 nm
Scene dynamic range accommodated with 4 gain levels:
– Aperture split provides two images/slit along the vertical direction of the focal plane
– Two integration times for additional discrimination
Wavelength-dependent resolution of prism spectrometer is consistent with ozone spectral detail over this range
Three slits provide three cross-track samples with a single spectrometer and no moving parts
All three slit samples are included on a single focal plane
Radiances nearly simultaneous in altitude and wavelength
Limb radiances sampled multiple times within 38 second integration time
Calibration stability maintained on-orbit by periodic solar observations
290 nm
350 nm
600 nm
1000 nm
M325 Model Atmosphere, SZA=40
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
6
OMPS Limb Sensor Views the Limb Along the Satellite Track
Photo from GSFC’s SOLSE/LORE Shuttle flight
• OMPS limb sensor has 3 slits separated by 4.25 degrees• 38 second reporting period: 250 km along track• 130 km (2.23 degree) vertical FOV at limb for 0-60 km coverage
plus offsets (pointing, orbital variation, Earth oblateness)
OMPS limb sampling
Center SlitLeft Slit Right Slit
Limb
0-65km
2.23
4.25250km
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
7
Radiance profiles constructed from 4 gain level images
Inverts neutral number density at 350 nm– Eliminates need for external EDR temperature and pressure above 20 km– Use external EDR temperature and pressure to derive density from 10 to 20 km– If external EDR unavailable, use climatology for 10 to 20 km
Inverts aerosol at non-ozone visible wavelengths– Simple aerosol model interpolates to ozone wavelengths– Wavelength triplet formulation reduces effects of aerosol on ozone when
aerosol inversion cannot be performed Solves for visible surface reflectances Solves for cloud fraction Multiple scattering tables include clouds at four pressure levels
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
10
Normalization Altitudes
OMPS channels selected to optimize limb profile performance
OMPS uses the UV and visible limb scatter spectrum to measure ozone– Middle and near-ultraviolet channels provide coverage from 28 to 60 km– Visible channels provide coverage from tropopause to 28 km
Additional channels between 350 and 1000 nm provide characterization of Rayleigh and aerosol scattering background
Ozone
Aerosol
SurfaceReflectance
NeutralNumberDensity
CloudFraction
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
11
Limb profile algorithm flow
Scene Characterization Cloud ID Scheme Cloud Properties
Surface Properties Cloud Fraction
Initial T, P, Density, Aerosol, Ozone, R
Surface Reflectances
O3 Inversion(Number Density)
O3 EDR
Density Inversion
Aerosol Inversion
Recent Limb ProfileNadir Profile
Cloud FractionReflectances
Density ProfileAerosol Profiles
O3 N.D.
O3 SDRIm(z)
Inorm (z)=Im(z)/Im(zNorm)
ConvergenceCriterion
Iterated Database
Convert O3 N.D. to VMR
No
Yes
SOLSE/LORE Algorithm
OMPS Enhancements
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
12
Scene Characterization
Spatial variation in cloud and surface reflectivity Radiances-weighted average (cloud fraction) of clear sky and cloud Iterated solution for cloud fraction from 347, 353 nm channels
Terrain Cloud
UV Visible UV Visible
ReflectanceN7 TOMS DB
(Herman &Celarier)
IteratedSolution 0.8 0.8
Pressure/Altitude CrIS
VIIRS/OMPS 1000nm
channel
Cloud
Ground
Baseline approach
Radiance multiple scattering
component depends on lower boundary
conditions
Limb Profiler
UV/VIS Limb Scatter Workshop- University of Bremen April 14-16, 2003
Use or disclosure of this informationmay be subject to United States export
control laws. For official use only.
13
Profile retrievals employ optimal estimation
Kernels define sensitivity of radiances to atmospheric constituents
Kernel shapes sharply peaked due to limb geometry - provides high vertical resolution
– Ozone errors due to sensor noise meet requirements
– C-Sigma selected as primary approach to altitude registration Precision ~ 120 m exceeds error allocation of 55m Accuracy ~ 500 m Will continue to study RSAS May combine both for operational use
OMPS algorithms to be tested on limb scatter observations– SAGE III, SOLSE/LORE 2, OSIRIS, SCIAMACHY, GOMOS
Engineering unit being built and tested fall-winter 2002-2003 First NPOESS flight currently planned for 2011
– Early flight of opportunity on NPP (Launch 2006)