# Presentation: 693791

## VIIRS Land Issues

- Robert Wolfe
- NASA GSFC Code 614.5
- NPP MODIS &VIIRS ScienceTeam Meeting
- May 14, 2008

## VIIRS Land Overview (1/3)

- Instrument
- NPP/FU1 is locked down and almost ready for TVAC testing
- testing expected to be completed by end-of-year
- workaround for thermal focus variation
- as-is cross-talk
- final characterization during TVAC (small, but not zero risk)
- more details at VIIRS SDR workshop in Jan. and summary tomorrow
- NPOESS/FU2 is being built
- plans include cross-talk and thermal focus fix
- need to make sure Fire band saturation fix is included

## VIIRS Land Overview (2/3)

- Data Systems
- Land PEATE on path to be very useful by end of year
- V1.5 algorithms are being integrated (Masuoka talk later)
- Alg. Eval: LDOPE tools, ability to compare MOIDS algorithms with NGST algs.
- CDR: First order are Diagnostic Data Records (DDRs)
- Algorithms – NGST not moving (at all or) in right direction
- Recent step backward on Albedo (BPSA will be default)

## VIIRS Land Overview (3/3)

- Interagency Coordination
- good working relationship
- NOAA being actively engaged – team is becoming deeper
- DOD participating, but not very deep
- Research to (&) Operations
- CDR funding priorities -- NOAA requesting prop. by end of year
- Cal/val support – discussions underway
- Team coordination
- Currently: meetings every two week
- include other agencies, IPO and VOAT – no longer have separate interagency coordination telecon
- include NGST?

## VIIRS Land Issues

- List originated with the NASA NPP Land Science Team
- Vetted by NOAA and DOD Land Scientists
- All Land algorithms are covered
- Issues are not in priority order
- Supporting details have been provided by ST at TIMs, previous VOAT meetings and other forums
- Issue list submitted to IPO on Jan. 18, 2008

## 1. Highest Priority Issues

- Make Surface Reflectance a Priority IP for cal/val
- bring forward the calibration phase to immediately post-launch and validation phase to after product has stabilized
- Need a list of planned land algorithm changes and schedule from NGST

## 2. Instrument Issues

- fix aggregation of fire band(s) saturated pixels
- explore download of full resolution data for FU1
- flag saturated pixels prior to aggregation for FU2
- need details on fire band high temp calibration
- watch list: cross-talk, band-to-band, MTF
- Science team access to EDU / FU1 Relative Spectral Responses (RSRs)

## 3. Geolocation

- understand SCI/OPS differences

## 4. Aerosols

- incorporate MODIS C5 updates

## 5. Surface Reflectance 

- incorporate MODIS C5 updates
- do not mask ocean or clouds

## 6. VIs

- formalize TOC NDVI
- perform blue band error assessment of possible change from 3-band to 2-band EVI

## 7. Albedo

- move from broadband to spectral dependent albedo product
- reconcile DPSA and BPSA
- evaluate against the specification at 1km, not at 4km
- current product is produced at 1km, but specification is evaluated at 4km

## 8. Snow

- use the NDSI regression method (Salomonson and Appel, 2006) to estimate snow fraction product at ~1 km resolution  (serves as surrogate for possible use of MESMA for snow fraction in future)
- MODIS proxy data testing should include late spring to early summer dates that image melting snow cover in boreal forests and Rocky Mountains

## 9. Sea-ice

- substantial problems for ice age
- assess effects of choice of ice vs. snow thermal emissivity for ice surface temperature EDR
- review status of relaxed specs. for albedo over sea ice
- updated/simplifed freshwater ice (ice vs. open water) algorithm still on request list – need formal status report from NGST/IPO

## 10. Surface Type

- there are significant implementation questions
- need plan/schedule from NGST/IPO
- key priority should be configuration of test-bed in NASA SDS Land PEATE for testing and evaluation

## 11. LST

- use different algorithm that explicitly has emissivity as an independent variable and does not depend on mid-IR surface emissivity
- determine how to deal with VIIRS pixels covering more than one land-cover type with different surface emissivities in the current land-cover based LST algorithm
- algorithm type should not change upon crossing into/out of sun-glint zone

## 12. Fire

- keep moving FRP change forward
- make sure context information is in product (cloud, etc.)

## 13. Cal/Val

- no strategy is in place to store long-term subsets of critical IPs (NSIPS does not plan to accommodate); availability of an extended set of IPs during field campaigns is in question

## 14. General

- full chain testing of gridded products
- chain testing with contaminated, degraded and challenging data
- fully realize reproducibility through granulated and gridded products
- make input pointer information useable outside of IDPS system
- cloud mask – may need tailored test(s) for specific land products
- NGST has not adhered to standard HDF5 format for xDRs

## Backup

## NASA NPP Land Science Team

| Science Team Members | Product |
| --- | --- |
| R. Wolfe | Geolocation  |
| E. Vermote, A. Lyapustin | Land Surface Reflectance |
| C. Schaff | Albedo |
| Z. Wan, S. Hook | Land Surface Temperature |
| D. Hall, J. Maslanik | Snow Cover  |
| M. Friedl | Surface Type |
| I. Csiszar, C. Justice | Active Fires, (Burned Area) |
| D. Hall, J. Maslanik | Ice Surface Temperature |
| A. Huete, R. Myneni | Vegetation Indices, (LAI) |

## Summary

- Issues should be addressed by the IPO
- Through “EDR Evaluation Tool” process?
- Good test of working together to improve algorithms
- Improved algorithms are more likely to meet EDR specs
- Larger margin (less risk)