the imager/sounder paradigm revisited third goes-r users conference

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The Imager/Sounder Paradigm Revisited

Third GOES-R Users ConferenceBroomfield, Colorado

May 11th, 2004

Joe Criscione, Jim Bremer, and Donald ChuSwales Aerospace

Joe Criscione 301-286-00702

Outline

• Examine Benefits of GEO

• Use GEO’s Assets as Paradigm

• Flow Instrument Architecture to Distributed Architecture

• Assess Impact to Requirements– Order of magnitude increase in Severe/Weather Mesoscale Sounding– Order of magnitude increase in Coastal Waters Imaging– Sacrifices CO2 spectral resolution in Full Disk Sounding

• Examine Feasibility and a Concept of Operations


How to Exploit GEO

• High temporal sampling of Full-Disk

– ABI images full disk every 5 minutes– All images from same point of view– Excellent way to observe change/flux

• Intense sampling of Region-of-Interest

– Can observe any point at any time– Ideal for observing rare/important

events• Coastal Waters, Severe Weather,

Natural and Man-Made Disasters


Use GEO’s Assets as Paradigm

Current Architecture

• Imager (ABI)– 2D products– Full disk/CONUS/Mesoscale

• Sounder (HES)– 3D products (and coastal waters)– Full disk/CONUS/Mesoscale

Proposed Architecture

• Full-Disk (ABI+)– 2D and 3D products– Full Disk

• Region-of-Interest (HES+/-)– 2D and 3D products– CONUS/Mesoscale

Flow Instrument Architecture To Spacecraft

Distributed Architecture

• Full-Disk S/C– Points at Nadir– ABI+ Scans Full Disk– Carries other payloads that

require a Nadir deck (GRB, GLM, etc. )

• Region-of-Interest S/C– Satellite points at target and

HES+/- Collects data WITHOUT SCANNING

• Scanner dominates radiometric and pointing error budgets

• Reduces Field of Regard by order of magnitude

• Can double aperture for HES+/-


What’s Changed?

Imager(ABI)

Sounder(HES)

30cm Aperture2-axis Scanner


Nadir Pointing Bus

Nadir Pointing Bus

Full-DiskImaging

• 5 min revisit• 0.5 km VIS• 2.0 km IR• 300:1 SNR• 0.1K NEDT•16 channels

MesoscaleSounding

• 4 min meso • 1 hr CONUS• 4km GSD• 64% DOEE• 1.0 cm-1• 0.1K NEDT

Full-DiskSounding

• 1 hr revisit• 10km GSD• 90% DOEE• 1.0 cm-1• 0.1K NEDT

CoastalWaters

• 3 hr revisit• 250m GSD• 300:1 SNR

Proposed ArchitectureFull-Disk

(ABI+)Region-Of-Interest

(HES+/-)


Nadir Pointing Bus

Full-DiskImaging

• 5 min revisit• 0.5 km VIS• 2.0 km IR• 300:1 SNR• 0.1K NEDT• 16 channels

NEDT: Noise Equivalent Delta TemperatureGSD: Ground Sample DistanceDOEE: Detector/Optics Ensquared Energycm-1: Spectral Channel Width in wavenumber

Flow InstrumentArchitecture to

S/C Architecture

Eliminate Scanner& Double Aperture

60 cm ApertureNo Scanner

Target Pointing Bus

Current Architecture

Full-DiskSounding

• 5 min revisit• 10km GSD• 90% DOEE• 3 cm-1 H2O• 10 cm-1 CO2

• 0.5K NEDT• Could do 4km GSD at expense of NEDT & DOEE• Concurrently with Imaging (NOT time shared)

Move Full-Disk Sounding to ABI

Trade Spectral Resolutionand NEDT for Revisit Time in Full-Disk Sounding

MesoscaleSounding

• 4 min meso • 1 hr CONUS• 4km GSD• 90% DOEE• 1.0 cm-1• 0.05K NEDT• 2km GSD possible

CoastalWaters

• 1 hr revisit• 75m GSD• 1000:1 SNR

Order of MagnitudeImprovement inCoastal Waters

Order of MagnitudeImprovement inMesoscale Sounding


Serendipity

• CO2 spectral resolution is hard– Narrow absorption feature– Best measured in Longwave where detectors are high cost/risk

• H2O spectral resolution is easy (comparatively)– Detector technology is mature – Lots of redundancy in the spectrum

• The atmosphere is cooperating for once– H2O fluctuates rapidly, but it is easy to observe– Temperature is hard to observe, but it is relatively stable

• Finesse it– Accurately measure H2O often and everywhere– Accurately measure temperature only in the CONUS/mesoscale regions


Feasibility

• Adding ~100 H2O channels to ABI+

– Data rate increase not overwhelming

• 100 at 10km = 1 at 1km

– Continuous variable filter on top of 2D array

• Same front end as current ABI concept

• Adds one filter and one detector array

• 6-8 micron region has mature detector technology

• Can tolerate noise and missing channels

Linear Variable FilterOptical Coating Laboratory

Inc.http://www.ocli.com/pdf_files/products/lvf_faqs.pdf


Feasibility (cont’d)

• 60 cm aperture for HES+/-– SEVIRI has 50 cm aperture

• Spinning Enhanced Visible and Infrared Imager• Flying on MSG right now• Has a single axis scanner• Weighs 260 kg (HES mass budget is 280 kg)

• Spacecraft pointing– Civilian high resolution LEO satellites point at targets with a 16,000 mph

ground track• GEO has a ground track of 0 mph

– Can use same bus for both satellites• Solar array can tilt 15 degrees off-normal with little effect on power• GOES-N bus could slew from nadir to edge of earth in ~2 minutes• Could raster scan CONUS with very little time wasted in slews

– Need to examine method for downlinking science data


Concept of Operations

• ABI+ – Uses Kalman filter to track atmospheric state

• Can use LEO observations to initialize Kalman filter• Tracking atmospheric state instead of retrieving state• Distribute atmospheric state hourly on 10km grid

– Potential for other products• Can observe winds at varying altitudes• Can distribute standard deviation of retrievals with hourly state

– Identifies targets for HES+/-

• HES+/-– Raster scans CONUS when there are no Regions-Of-Interest

• Can interleave Regions-Of-Interest with CONUS scans– Has high resolution land bands as well as fire channel– Can re-initialize parts of full disk that fall out of convergence for the ABI+

Kalman filter (no need to wait for LEO pass)

• ABI+, HES+/-, and NPOESS work as integrated system


Conclusion

• Full-Disk/Region-Of-Interest Partitioning

– Sacrifices spectral resolution of full disk soundings

– No impact to full disk imaging products

– Order of magnitude improvement to severe weather/mesoscale soundings

– Order of magnitude improvement to coastal waters

• Same cost and risk– Achieves gains by

optimizing spacecraft/instrument system

– Balances full disk sounding needs and instrument complexity

250m GSD

75m GSD

the imager/sounder paradigm revisited third goes-r users conference

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