NPP VIIRS Aerosol Products: Overview, early cal/val results, and data assimilation results from NAVDAS-AOD Edward Hyer Naval Research Laboratory JCSDA Symposium 11 October 2012
Feb 07, 2016
NPP VIIRS Aerosol Products:Overview, early cal/val results, and data assimilation results from NAVDAS-AOD
Edward HyerNaval Research Laboratory
JCSDA Symposium11 October 2012
In this talk
• Overview of NPP VIIRS aerosol products• Status of NPP Cal/Val effort• Comparison of MODIS and VIIRS products• Preparation of DA-ready obs from VIIRS• Impact of VIIRS obs in NAAPS• Future Work• MODIS DA-ready AOD now available from LANCE
3
NPP Visible Infrared Imaging Radiometer Suite (VIIRS)
0130, 1330 local time orbits“Early afternoon slot”
Credit: NASA
October28 2011
• OLS
Heritage Operational and R&D Sensors
4
AVHRR
SeaWiFSMODIS
R&D Sensors
Ocean ColorBands
RotatingTelescope
Band Selection/Continuity Thin Cirrus Band Solar Diffuser Earthshine Lessons Learned
Operational Sensors High Spatial Resolution Day/Night Band Minimize Resolution
Growth Over Scan
VIIRS
275 kg 22 bands
OMM EM
Radiometric Accuracy
SST Band Continuity
33 kg 5 bands
45 kg 8 bands
220 kg 36 bands
OLS
74 kg 2 bands
Credit: Northrup Grumman & Raytheon
Heritage Capabilities
5
0.4 140.6 0.7 0.8 0.90.5 1.2 1.8 6 82.4 4 10 12
[micron]
OLS
AVHRR
SeaWiFS
MODIS
VIIRS DNB
Low Light Imagery
Long wave IRMid wave IRVisible Breaks in scale
Credit: Northrup Grumman & Raytheon
Simplified VIIRS Aerosol Process
SDR: Calibrated TOA Radiances / Reflectances
VIIRS Cloud Mask
Aerosol Intermediate
Product IVAOT
Met. Fields (NCEP)(NOGAPS backup)
NAAPS Aerosol Optical Depth
Aerosol EDR VAOOO (contains no NAAPS)
VIIRS Aerosol EDR Product
• ~6km resolution– 8x8 ~750m pixels
• Retrieved: – AOT – Angstrom Exponent– Suspended Matter Type
• Many Quality Flags: – Cloud (incl. adjacent)– Glint and other geometry– Input data quality
• Retrieval is based on LUTs generated with 6S
• Heritage is MOD09 Surface Reflectance
• Over-ocean similar to MOD04– Fine-coarse mixture retrieved
explicitly
• Over-land uses different aerosol models– Single model (fine+coarse) is
retrieved via LUT
Aerosol EDR VAOOO
Status of Aerosol Cal/Val
• Aerosol EDR is sum of Parts:– VIIRS SDR
radiances/reflectances: These are still Beta, Provisional status will be considered later this fall
– VIIRS Cloud Mask: basic tuning complete, product is still Beta
• Aerosol EDR is recently partially advanced to ‘Beta’ maturity:– Global AOD– Over-ocean Aerosol Size
Parameter– NOT over-land Aerosol
Size Parameter– NOT Suspended Matter
EDR
MODIS and VIIRS AOD
MODIS-Aqua VIIRS-NPP
Credit: Min Oo, Bob Holz, Atmospheres PEATE, University of Wisconsinhttp://peate.ssec.wisc.edu/flo/npp/gridding?date=2012%2F09%2F24
MODIS and VIIRS AOD
MODIS-Aqua VIIRS-NPP
Credit: Min Oo, Bob Holz, Atmospheres PEATE, University of Wisconsinhttp://peate.ssec.wisc.edu/flo/npp/gridding?date=2012%2F09%2F24
GA
P
NO
GA
P
VIIRS has wider swath– complete overlap even at equator
MODIS and VIIRS AOD
MODIS-Aqua VIIRS-NPP
Credit: Min Oo, Bob Holz, Atmospheres PEATE, University of Wisconsinhttp://peate.ssec.wisc.edu/flo/npp/gridding?date=2012%2F09%2F24
VIIRS and MODIS show broad agreement in large features
MODIS and VIIRS AOD
MODIS-Aqua VIIRS-NPP
Credit: Min Oo, Bob Holz, Atmospheres PEATE, University of Wisconsinhttp://peate.ssec.wisc.edu/flo/npp/gridding?date=2012%2F09%2F24
VIIRS and MODIS have different cloud screening– VIIRS is still being characterized. Both products must avoid clouds for accurate retrieval.
MODIS and VIIRS AOD
MODIS-Aqua VIIRS-NPP
Credit: Min Oo, Bob Holz, Atmospheres PEATE, University of Wisconsinhttp://peate.ssec.wisc.edu/flo/npp/gridding?date=2012%2F09%2F24
VIIRS and MODIS show significant differences over land
VIIRS vs. AERONET AOD over ocean
• Best QA only• Low mean bias• Not enough data to
clearly diagnose bias at higher AOD
VIIRS vs. AERONET AOD over land
• Best QA only• Significant positive
mean bias• Positive bias for all AOD
ranges observed
AOD Pre-processing for DA
MODIS• NRL & University of North
Dakota developed method starting with MOD04 Level 2 data
• Extensive filtering for cloud, surface, etc.
• Empirical Correction• Prognostic Uncertainty
Model• Now a product produced in
NRT at NASA LANCE
NPP VIIRS• Method under
development• Currently only filters
using built-in QA• No corrections• Aggregated to NAAPS 1-
degree resolution
NAVDAS-AOD Testbed
Start with best analysis from research run (includes assimilated MODIS AOD)
NAVDAS-AOD Testbed
Assimilate NPP VIIRS AOD (+/- 3 hours)
NAVDAS-AOD Testbed
Initialize 72-hour forecasts from MODIS and MODIS+NPP analyses
NAVDAS-AOD Testbed
Compare forecast with obs to evaluate propagation of differences
MODIS obs do not show high AOD over ocean west of Hawaii
NAVDAS-AOD Testbed
Compare forecast with obs to evaluate propagation of AOD differences
MODIS and VIIRS obs do not show high AOD over ocean west of Hawaii
Much More Work To Do
• Quantitative Evaluation of NAAPS-MODIS vs NAAPS-MODIS+NPP analysis and forecast
• Determination of impact on forecast error of including over-ocean VIIRS AOD
• Construction and evaluation of prognostic error model for VIIRS AOD
• Construction of higher-resolution products
The NRL-UND MODIS Level 3 Aerosol Optical Depth Product
14 April 2011 Hyer ISRSE34 Sydney 23 of 25
• 0.5 degree, 6-hourly, available within 4 hours of overpass, HDF format with full metadata
• Available now: nrt1.modaps.nascom.nasa.gov
Thank you
• Thanks to:– NPP VIIRS Cal/Val teams– Atmospheres PEATE (U. Wisconsin)– NRL Aerosol and Radiation Section– Jianglong Zhang and group at UND
• Sponsors:– NOAA (NPP Cal/Val)– ONR (AOD Preprocessing and QA/QC)– NASA AQAST (transition of DA-ready AOD to LANCE)