Post on 20-May-2015
IGARSS 2011-1WJB 04/12/2023
NPP ATMS Prelaunch Performance Assessment and Sensor Data Record Validation
W. J. Blackwell, L. Chidester (SDL), C. Cull, E. J. Kim (NASA GSFC), R. V. Leslie,
C.-H. Lyu (NASA GSFC), T. Mo (NOAA STAR), and I. Osaretin
IGARSS
July 25, 2011
This work was sponsored by the National Oceanographic and Atmospheric Administration under Air Force Contract FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the
authors and are not necessarily endorsed by the United States Government.
IGARSS 2011-2WJB 04/12/2023
Outline
• ATMS Overview– Background and development– Performance
• Prelaunch testing– Antenna– Radiometric TVAC
• Post-launch validation of sensor/product performance– Planning/schedule/objectives– Tasks
• Summary
IGARSS 2011-3WJB 04/12/2023
NPP (NPOESS Preparatory Project)Oct. 25, 2011 Launch
National Polar-orbiting Operational Environmental Satellite
System → Joint Polar Satellite System
National Polar-orbiting Operational Environmental Satellite
System → Joint Polar Satellite System
NPOESS Preparatory Project
• Launch site: Vandenberg AFB
• Launch vehicle: Boeing Delta II
• Spacecraft: Ball Aerospace Commercial Platform 2000
• Instruments: VIIRS, CrIS, ATMS, OMPS, & CERES
• Orbits: 824 km (NPP); sun-synchronous with a 1:30 p.m. local-time ascending node crossing
IGARSS 2011-4WJB 04/12/2023
NPOESS Preparatory ProjectOctober 25, 2011 Launch
Photo courtesy of Ball Aerospace, Boulder, CO.
IGARSS 2011-5WJB 04/12/2023
Advanced Technology Microwave Sounder (ATMS)
ATMS is a 22 channel MW sounder
Frequencies range from 23-183 GHz
Total-power, two-point external calibration
Continuous cross-track scanning, with torque & momentum compensation
Orbits: 833 km (JPSS); 824 km (NPP); sun-synchronous
Thermal control by spacecraft cold plate
Contractor: Northrop Grumman Electronics Systems (NGES)
70 cm
IGARSS 2011-6WJB 04/12/2023
ATMS Development
• ATMS NPP unit (“F1") developed by NASA/Goddard– ATMS NPP unit delivered in 2005– ATMS JPSS-1 unit (“F2”) currently in development
(antenna and TVAC testing in 2011/12, delivery in 2012)
• Principal challenges/advantages:– Reduced size/power relative to AMSU
Scan drive mechanism MMIC technology
– Improved spatial coverage (no gaps between swaths)– Nyquist spatial sampling of temperature bands (improved
information content relative to AMSU-A)
IGARSS 2011-7WJB 04/12/2023
ATMS Design Challenge
– 70x40x60 cm – 110 W– 85 kg– 8 year life
AMSU-A1
AMSU-A2
MHS
Reduce the volume by 3xReduce the volume by 3x
• 75x70x64 cm• 24 W• 50 kg• 3-yr life
• 73x30x61 cm• 67 W• 54 kg• 3-yr life
• 75x56x69 cm• 61 W• 50 kg• 4-yr life
Figure courtesy NGES, Azusa, CA
IGARSS 2011-8WJB 04/12/2023
Atmospheric Transmission at Microwave Wavelengths
The frequency dependence of atmospheric absorption allows different altitudes to be sensed by spacing channels along absorption lines
ATMS channels
IGARSS 2011-9WJB 04/12/2023
Spectral Differences: ATMS vs. AMSU/MHS
Ch GHz Pol Ch GHz Pol
1 23.8 QV 1 23.8 QV
2 31.399 QV 2 31.4 QV
3 50.299 QV 3 50.3 QH
4 51.76 QH
4 52.8 QV 5 52.8 QH
5 53.595 ± 0.115 QH 6 53.596 ± 0.115 QH
6 54.4 QH 7 54.4 QH
7 54.94 QV 8 54.94 QH
8 55.5 QH 9 55.5 QH
9 fo = 57.29 QH 10 fo = 57.29 QH
10 fo ± 0.217 QH 11 fo±0.3222±0.217 QH
11 fo±0.3222±0.048 QH 12 fo± 0.3222±0.048 QH
12 fo ±0.3222±0.022 QH 13 fo±0.3222±0.022 QH
13 fo± 0.3222±0.010 QH 14 fo±0.3222 ±0.010 QH
14 fo±0.3222±0.0045 QH 15 fo± 0.3222±0.0045 QH
15 89.0 QV
16 89.0 QV 16 88.2 QV
17 157.0 QV 17 165.5 QH
18 183.31 ± 1 QH 18 183.31 ± 7 QH
19 183.31 ± 3 QH 19 183.31 ± 4.5 QH
20 191.31 QV 20 183.31 ± 3 QH
21 183.31 ± 1.8 QH
22 183.31 ± 1 QH
Exact match to AMSU/MHS
Only Polarization differentUnique Passband
Unique Passband, and Pol. different from closest AMSU/MHS channels
MH
SAM
SU-A
AMSU/MHS ATMS
• ATMS has 22 channels and AMSU/MHS have 20, with polarization differences between some channels
− QV = Quasi-vertical; polarization vector is parallel to the scan plane at nadir
− QH = Quasi-horizontal; polarization vector is perpendicular to the scan plane at nadir
IGARSS 2011-10WJB 04/12/2023
Spatial Differences: ATMS vs. AMSU/MHS
Beamwidth (degrees)
ATMS AMSU/MHS
23/31 GHz 5.2 3.3
50-60 GHz 2.2 3.3
89-GHz 2.2 1.1
160-183 GHz 1.1 1.1
Spatial sampling
ATMS AMSU/MHS
23/31 GHz 1.11 3.33
50-60 GHz 1.11 3.33
89-GHz 1.11 1.11
160-183 GHz 1.11 1.11
Swath (km) ~2600 ~2200
ATMS scan period: 8/3 sec; AMSU-A scan period: 8 secATMS measures 96 footprints per scan (30/90 for AMSU-A/B)
IGARSS 2011-11WJB 04/12/2023
Summary of Key Sensor Parameters
Parameter PFM Measurement
Envelope dimensions 70x60x40 cm
Mass 75 kg
Operational average power 100 W
Operational peak power 200 W
Data rate 30 kbps
Absolute calibration accuracy 0.6 K
Maximum nonlinearity 0.35 K
Frequency stability 0.5 MHz
Pointing knowledge 0.03 degrees
NEDT 0.3/0.5/1.0/2.0 K
IGARSS 2011-12WJB 04/12/2023
ATMS Data Products
Data Product Description
RDR (Raw Data Record) FOV1 antenna temperature (counts)
TDR (Temperature Data Record) FOV1 antenna temperature (K)
SDR (Sensor Data Record) FOR1 brightness temperature (K)
EDR (Environmental Data Record) P/T/WV profile
“CDR” (Climate Data Record) “Climate-optimized” product
IP (Intermediate Product) Used to generate EDR/CDR
1FOV = ATMS “Field of View”; FOR = CrIMSS “Field of Regard”RDR, TDR, SDR, and EDR products will be available via CLASS
IGARSS 2011-13WJB 04/12/2023
Outline
• ATMS Overview– Background and development– Performance
• Prelaunch testing– Antenna– Radiometric TVAC
• Post-launch validation of sensor/product performance– Planning/schedule/objectives– Tasks
• Summary
IGARSS 2011-14WJB 04/12/2023
ATMS Pre-Launch Testing
• Essential for two objectives:– Ensure sensor meets performance specifications– Ensure calibration parameters that are needed for SDR processing are
adequately and accurately defined
• PFM testing revealed several issues that will require calibration corrections in the SDR:– Non-linearity (temperature-dependent for 31.4-GHz channel)– Cross-polarization (sometimes 10X higher than AMSU)– Antenna beam spillover from secondary parabolic reflector approaching
2% for some channels
• A variety of prelaunch testing is performed to assess performance and reliability– EMI/EMC - anechoic chamber for both emitted and susceptible
measurements – Mechanical – mass, CG, vibration, & torque on various fixtures– Radiometric – thermal vacuum (TVac) testing– Antenna – Compact Antenna Test Range (CATR)
IGARSS 2011-15WJB 04/12/2023
Compact Antenna Range Testing
• Compact Antenna Test Range– RF source illuminates the Antenna Under
Test (AUT), i.e., ATMS antenna subsystem– Uses a parabolic reflector to collimate the
electromagnetic radiation to illuminate the AUT in the far-field region
– AUT is attached to a positioner to rotate the AUT into the proper orientation
• Test measures the power received by the AUT compared to a standard antenna with a known antenna gain pattern
• Specifications verified: – Beam pointing accuracy– Beamwidth– Beam efficiency– Earth intercept
IGARSS 2011-16WJB 04/12/2023
Thermal Vacuum Parameters
• Dynamic range (brightness temperature range of 93-320 K)
• NEΔT (sensitivity)• Calibration accuracy (bias)• Linearity (deviation from linear
regression)• Short term gain fluctuation
(ΔG/G) (gain stability or 1/f noise)
• Hysteresis (repeatability)
NASA/LARC
• Measure the calibration parameters that are needed by the SDR algorithm (e.g., non-linearity correction factor)
• Validate that the sensor meets performance requirements• Provide pre-launch performance validation in a flight-like
environment
IGARSS 2011-17WJB 04/12/2023
Outline
• ATMS Overview– Background and development– Performance
• Prelaunch testing– Antenna– Radiometric TVAC
• Post-launch validation of sensor/product performance– Planning/schedule/objectives– Tasks
• Summary
IGARSS 2011-18WJB 04/12/2023
Post-Launch Cal/Val Timeline
L+13
L+90
IPO/NGAS ATMS
L+ 40L+12
NASA/NGES NGES/NASA
IGARSS 2011-19WJB 04/12/2023
ATMS Post-Launch Calibration/Validation in a Nutshell
• Post-launch is Cal/Val has four phases: Activation, Checkout, Intensive Cal/Val, and Long-term Trending
• Tasks within the phases can be categorized:– Sensor Evaluation: interference, performance evaluation, etc.– TDR/SDR Verification: geolocation, accuracy, etc.– SDR Algorithm Tunable Parameters: bias correction, space view
sector, etc.
• Activation Phase: Sensor is turned on and a sensor functional evaluation is performed; ATMS is collecting science data
• Checkout Phase: Performance evaluation and RFI evaluations
• Intensive Cal/Val: Verification of SDR attributes such as geolocation, resampling, brightness temperature accuracy (Simultaneous Nadir Overpass, Double Difference, radiosondes/NWP simulations, aircraft verification campaigns), and satellite maneuvers
IGARSS 2011-20WJB 04/12/2023
ATMS On-Orbit FOV Characterization
• Spacecraft maneuvers (constant pitch up or roll, for example) could be used to sweep antenna beam across vicarious calibration sources– Moon (probably too weak/broad for pattern assessment)– Earth’s limb (requires atmospheric characterization)
Focus of today’s presentation– Land/sea boundary (good for verification of geolocation)
• With knowledge of the atmospheric state, the antenna pattern can be recovered with deconvolution techniques
• Objectives of this study - quantitatively assess:– The benefits of various maneuvers
How accurately can the pattern be recovered?– The limitations of this approach
How much roll/pitch is needed for an adequate measurement? The error sources and their impact
IGARSS 2011-21WJB 04/12/2023
TB’s Across Earth/Space Transition
62.1
7°
BE
YO
ND
STA
ND
AR
D A
TM
OS
PH
ER
E
SURFACE
LIMB(STANDARD
ATMOSPHERE)
IGARSS 2011-22WJB 04/12/2023
NPOESS Airborne Sounder Testbed
OBJECTIVES
• Satellite calibration/validation
• Simulate spaceborne instruments
(i.e. CrIS, ATMS, IASI)– Preview high resolution products
– Evaluate key EDR algorithms
INSTRUMENTS: NAST-I & NAST-M
NAST- I: IR Interferometer Sounder
NAST- M: Microwave Sounder5 Bands: 23/31 (to be added), 54, 118, 183, 425 GHz
118
18354
425
NAST- M
NAST
~100km
Cruising altitude: ~17-20 km
Cross-track scanning: - 65º to 65º
IGARSS 2011-23WJB 04/12/2023
MetOp Satellite Validation
April 20th, 2007 collection
MetOp
path
Gulf of Mexico
NAST-M [Kelvin]
AM
SU
-A (
Met
Op
) [K
elvi
n] Tb Comparison AMSU-A
50.352.853.7554.454.94
-0.25K1.4K
-0.2K-0.2K-0.9K
GHz Bias
JAIVEx
<20min
IGARSS 2011-24WJB 04/12/2023
Summary
• All key radiometric requirements were satisfied
• Radiometric accuracy exceeds 1K
• Radiometric sensitivity exceeds requirements– Similar to AMSU for similar effective footprint sizes
• Linearity performance generally exceeds AMSU
• Antenna pattern testing indicates good performance– Opportunity for spacecraft maneuvers allows improved
characterization of ATMS spatial response function
• Post-launch cal/val plans are well defined– Readiness exercises ongoing– Areas to watch have been illuminated during prelaunch testing
IGARSS 2011-25WJB 04/12/2023
Backup Slides
IGARSS 2011-26WJB 04/12/2023
Utility of Aircraft Underflights
What do aircraft measurements provide that we cannot get anywhere else?– Why not just compare to radiosondes or NWP?
• Direct radiance comparisons– Removes modeling errors
• Mobile platform– High spatial & temporal coincidence achievable
• Spectral response matched to satellite– With additional radiometers for calibration
• Higher spatial resolution than satellite• Additional instrumentation deployed
– Coincident video data– Dropsondes
Example video image
Solar glint
Ocean
Clouds
IGARSS 2011-27WJB 04/12/2023
Synergistic Use of MW+IR:
Infrared Provides High Spatial Resolution
For example, CrIS provides 15km horizontal and 1km vertical resolution
IGARSS 2011-28WJB 04/12/2023
Passive Microwave Measurements Provide Low
Spatial Resolution, but Penetrate Clouds
For example, ATMS provides 33km horizontal and 3km vertical resolution
IGARSS 2011-29WJB 04/12/2023
AMSU-A: Large, Positive Forecast Impact
Source: Gelaro, Rienecker et al., 2008, NASA GMAO
IGARSS 2011-30WJB 04/12/2023
ATMS Storm Mapping:Improvements Relative to AMSU
Source: Surussavadee and Staelin, NASA PMM Presentation, 7/08