# Presentation: 099888

## Transitioning

- from
- MODIS to VIIRS

- Presented to the EOS/NPP Direct Readout Meeting
- Benevento, Italy
- October 3-6, 2005
- By
- Robert E Murphy1, John E Clement2 & Debra Olejniczak3
- 1 Integrated Program Office/George Mason University
- 2 Raytheon/Santa Barbara Remote Sensing
- 3 Northrop Grumman Space Technologies

## Outline

**VIIRS at a Glance**
**MODIS & VIIRS**
**VIIRS Flights**
**Geometric Properties **
**Spectral & Radiometric Properties**
**Pre-Launch & On-Orbit Calibration**
**Design Features**
**Access to Data & Algorithms**
**Data Quality**
**Common Cloud Mask**

## VIIRS at a Glance

**VIIRS: Visible Infrared Imager Radiometer Suite**
**VIIRS will continue the observational program of:**
- OLS: Optical Line Scanner
- AVHRR: Advanced Very High Resolution Radiometer
- SeaWiFS: Sea viewing Wide Field-of-view Sensor
- MODIS: Moderate Resolution Imaging Spectroradiometer
**VIIRS will provide operational and research users with:**
- Spectral coverage from 412 nm to 12 microns in 22 bands
- Imagery at 371 m nadir resolution in 5 bands
- Moderate resolution (~742 m at nadir) radiometric quality data
- Complete global daily coverage with a single sensor
- 8-hour refresh in the NPOESS constellation (ca 2011)
**Routine data products of:**
- Cloud cover, cloud layers
- Cloud and aerosol physical properties
- Land & ocean biosphere properties, snow & ice
- Sea Surface Temperature, Land & Ice Temperatures

## VIIRS Design is Evolutionary from MODIS

**Spatial resolution & MTF improved**
- 341m & 742 m at nadir, reduced pixel growth
**Improved stray light control with Rotating telescope**
**Added “day-night” band for cross-terminator imaging**
**Higher orbit yields full global coverage in one day**
**Comparable radiometric & spectral quality**
- 12 bit data
- Equivalent on-board calibrators
- Characterization equivalent to Aqua MODIS
- Bandpasses widened with no loss of specificity
**Bandset reduced from 36 to 22**
- MODIS supported research products not yet proven for operational purposes
- Ocean Fluorescence, CO2 “slicing bands”, Ozone

## VIIRS Flights

**First flight is on the NPOESS Preparatory Project (NPP)**
- April 2008 launch
- 824 Km Sun Synchronous Orbit with 10:30 descending orbit
- 16 ground-track repeat similar to Landsat, Terra, Aqua, Aura
- Other NPP sensors:
- Cross-Track Infrared Sounder (CrIS)
- Advanced Technology Microwave Sounder (ATMS)
- Ozone Mapping & Profiling Sensor (OMPS)
- Continuous Direct Broadcast of all data (X-Band)
**Continuous flights on the operational NPOESS (National Polar-Orbiting Operational Environmental Satellite System)**
- 1st Launch ~ 2011 into 833 Km orbit with 17:30 crossing time
- Subsequent launches into 13:30 and 21:30 ascending orbits
- Replacement satellites will be launched on failure of VIIRS
- Continues into the indefinite future
- Continuous Direct Broadcast of all data (X-Band)
- Low Rate Data (LRD) also available at L-Band with lossy compression

## Geometric Properties

**Pixel aggregation scheme provides reduced pixel growth to edge of scan**
**At nadir, 3 pixels aggregated into one with very high radiometric quality and improved MTF**
- 742 m or 371 m pixels
**At 530 km off-nadir switch to 2 pixel aggregation**
- 1,104 m or 552 m pixels at 850 km from nadir
**From 850 km to edge of scan uses no aggregation**
- 1,600 m or 800 m pixels at edge of scan
**All dual gain bands are transmitted un-aggregated**
- Aggregation preformed in ground processing
**Band-to-band registration**
- For most bands the requirement is 64% area overlap
- For the imagery (371 m) & SST bands, it is 80% area overlap

## Pixel Aggregation Provides High SNRat Nadir, Reduced Pixel Growth

**Pixel Aggregation Provides High SNR****at Nadir, Reduced Pixel Growth**

## VIIRS Band to Band Registration Requirements

- BBR between 2 bands is defined as % of pixel area that would be common between pixels of specified Horizontal Spatial Resolution (HSR) on a side, with same centroids as corresponding pixels in the 2 bands

- HSR Scan

- S

- T

- HSR Trk

- T/HSR Track = Track
- S/HSR Scan = Scan
- Registration = (1-Track) (1-Scan)

## Spectral-Radiometic Properties

**22 Spectral bands on 3 focal planes**
- Vis/NIR focal plane covers 412 nm to 865 nm w/ 10 bands
- Operates at ambient temperature
- 6 dual gain bands support both land & ocean applications
- 2 bands at 371 m nadir resolution w/ high MTF for VI, etc
- 1 panchromatic band for terminator & nighttime imagery
- SW/MWIR focal plane covers 1.24 to 4.05w/ 8 bands
- Cooled to 80K
- 1.6 & 3.7 bands duplicated ... 1 radiometric & 1 imaging (371 m)
- Includes 1.38band for cirrus detection
- 4.05 band has saturation temperature of 635 K for fire studies
- LWIR focal plane covers 8.55 to 12 w/ 4 bands
- Cooled to 80K
- Broad band centered on 11.5 with 371 m resolution
**12 bit data in all bands**
**All 742 m bands (& Vis/NIR 371 m bands) optimized for radiometry**

## Comparison of MODIS & VIIRS Bands

## Moderate Resolution Bands Have 16 Detectors Downtrack

## VIIRS Vis/NIR Bands

- SNR values are as specified for un-aggregated pixel.
- At nadir SNR will be ~      better after aggregation. (Predicted are better still)

## VIIRS S/MW & LW IR Bands

- SNR values are as specified for un-aggregated pixel.
- At nadir SNR will be ~      better after aggregation. (Predicted are better still)

## Pre-Launch & On-Orbit Calibration

**Intensive MODIS-like pre-launch characterization & calibration**
**Solar Diffuser (SD) calibration every terminator crossing**
- 1-time door deployed after launch
**Solar Diffuser Stability Monitor (SDSM) to track SD degradation**
- 8 spectral bands from 412 nm to 935 nm
- Ratioing radiometer looks at Sun and SD via integrating sphere
**On-Board Black Body Calibrator (OBC) viewed every scan (1.7864 seconds)**
- Temperature maintained at 290 ±0.2 K
- Can be heated to 315 K for linearity test

## Visible Infrared Imager Spectroradiometer (VIIRS)

## Solar Diffuser Screen & Solar Diffuser Stability Monitor

## Yields Lower Scattered Light than MODIS

## Access to Data & Algorithms

**All data will be transmitted to the ground in real time**
- X-Band
- 15 Mbps (NPP) 20 Mbps (NPOESS)
- Convolutional Coding
- QPSK (NPP) OQPSK (NPOESS)
- NRZ-M compression
**Available without fee to all users**
- Data deniability feature may be exercised in unusual circumstances
**2.4 m class X-band system sufficient**
**Operational algorithms will be made available prior to launch**
**NASA GSFC will provide:**
- Real-Time Software Telemetry Processing System
- Ground-Based Attitude Determination module
- Stand-alone Instrument Level-1 (SDR) & select Level-2 (EDR) algorithms
- Visualization & data formatting tools
- See _[http://directreadout.gsfc.nasa.gov](http://directreadout.gsfc.nasa.gov/)_

- _[http://directreadout.gsfc.nasa.gov](http://directreadout.gsfc.nasa.gov/)_

## Data Quality

**An NPOESS data product is known as an Environmental Data Record (EDR) ... roughly equivalent to a Level 2 product**
**Quality of EDR’s is being formally assessed by NGST**
- Separate assessment of accuracy, precision and uncertainty pre IORD requirements
- In general, EDR’s are expected to meet the IORD requirements  Performance is similar to MODIS
- Fire product will not meet MODIS standard due to
- Higher spatial resolution leads to easier saturation
- Dynamic range less than MODIS in order to provide needed SNR for Key Performance Parameters of Sea Surface Temperature & Imagery
**Additional studies underway by IPO and NASA-supported science investigators**

## Common Cloud Mask

**A common cloud mask is used for all VIIRS data products**
- Although MODIS has a cloud mask, the algorithms for most data products make their own tests and decisions
**Mask consists of 5 bytes**
**Uses all bands except M-2, M3, M6, I-3 & DNB**

## VCM Output Bit Structure

**0**

**1**

**3**

**4**

*Byte*

*Byte*

*Bit*

*Bit*

**0-1**

**0-1**

**6-7**

**4-7**

**6**

**4-7**

**Cloud Mask Quality**

**Adjacent Pixel Cloud Confident Value**

**Sun Glint**

**Imagery Resolution BTD Test**

**2-3**

**Cloud Confidence**

**Land/Water Background**

**Shadow Detected**

**0-2**

**3**

**0-3**

**5**

**Spares (4)**

**4-7**

**2**

**4**

**5**

**Day/Night**

**Snow/Ice Surface**

**Imagery Resolution RI1 Test**

**Imagery Resolution RI2 Test**

**0-2**

**Cloud Phase**

**2**

**3**

**Conifer Boreal Forest**

**Spatial Uniformity Test**

**7**

**5**

**4**

**Cirrus (IR-BTD)**

**Cirrus (solar-M9)**

**Fire detected**

**Non-Cloud Obstruction**

**0**

**7**

**6**

**5**

**4**

**3**

**2**

**1**

**Visible Ref Test (M5)**

**BTD Test (M15-M12)**

**Tri-Spectral IR Test**

**High Cloud (M12-M16)**

**IR Threshold (BTM15)**

**BTD Test (M12-M13)**

**Visible Ratio (M7/M5)**

**Visible Ref Test (M7)**

**3**

**Thin Cirrus Flag**

## Cloud Module Process Flow

**Cloud Optical Properties (COP)**

**Cloud Top Properties (CTP)**

**Perform Parallax Correction (PPC)**

**Cloud Cover/ Layers (CCL)**

**Cloud Base Height (CBH)**

**Grid Cloud EDRs (GCE)**

**Cloud Mask (VCM)**

**SDRs**

**VCM**

**CTT, CTP, CTH**

**COT,****CPS, CTT***

**CCL****

**CBH**

**VCM, COT, CPS, CTT, CTP, CTH**

**COT, CPS, CTT, CTP, CTH, CCL, CBH**

**CCL********

***Slide provided by AER, Inc.***

## Summary

**VIIRS will provide long term continuity of imaging radiometry of moderate (371 m & 742 m) resolution for the indefinite future**
**First launch is April 2008**
**Radiometric quality is similar to MODIS**
**Spatial resolution improved over MODIS with pixel aggregation & high MTF bands**
**Direct broadcast of all data**

## Acknowledgments

- The 3 authors represent the 3 organizations that are managing the development of the VIIRS sensor & its data products. A partial list of major contributors is as follows:
- Raytheon: Robert Aguilera*, Vernon Alfred, Phil Ardanuy, Rodney Durham, Ron Estes, Gerry Godden, Eric Johnson, Richard Julian, Peter Kealy#, Craig Kent, Shawn Miller, Jay Neuman, Cliff Nichols, Michael Pavloff, John Pollicastro, Dan Pelham, Don Pies, Carl Scheuler, Mark Schwarz, Joe Walker, Mike Whalen, Jeanette Woo, James Young
- Northrop Grumman: Lane Darnton, Mark Frink, Gary Grimm, Terry Larson, David Leone, Lushalan Liao, James McCarthy, Stephen Mills, Merit Shoucri
- Integrated Program Office & Aerospace: Neal Baker, Michael Crison, Frank DeLuccia, David Glackin, Michael Haas, Tanya Scalione, Arthur Schwalb, Hilmer Swenson, Carol Welsh
- In addition, there have been major contributions from NASA & its university community, NOAA, and the Air Force Weather Agency
- NASA & its university community: William Barnes, Wayne Esaias, Bruce Guenther, Alexi Lyapustin, Peter Minnett, Jeffrey Privette
- NOAA: Andrew Heidinger, Paul Menzel
- AFWA: Thomas Kopp

- * Also served at NGST

- # Also served at NASA

## Backup Slides

## NPOESS is a Tri-agency Effort to Combine Operational Environmental Polar Satellite Activities

**Mission**
**Provide a national, operational, polar-orbiting environmental capability**
**Achieve National Performance Review savings by converging DoD and NOAA polar satellite programs**
**Incorporate new technologies from NASA and others**
**Incorporate, where appropriate,  International Cooperation (EUMETSAT)**

- NPOESS

**NPOESS**

**Notes:**
...establishing the NPOESS program was signed in May 1995.  The Departments of Commerce and Defense and NASA created the NPOESS Integrated Program Office (IPO) to develop, acquire, manage, and operate the next generation of polar-orbiting operational environmental satellites.  As part of this effort, the United States has partnered with the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) to provide long-term continuity of observations from polar orbit that will continue and improve the operational meteorological and environmental forecasting and global climate monitoring services of the participating organizations.
NPOESS is well positioned to meet its mission.
<NEXT SLIDE>

## What is NPP?

**NPP is a “bridging mission” that provides for the continuation of measurement series initiated with EOS Terra & Aqua for NASA’s global change research**
**Climate change**
**Global carbon cycle**
**Global water cycle**
**NPP provides risk reduction for the National Polar-Orbiting Operational Environmental Satellite System (NPOESS) which will continue these measurements into the indefinite future**
**NPP is a joint program of NASA and the Integrated Program Office (IPO), the tri-agency activity that is responsible for NPOESS**

## NPP Sensors

**NPP Sensors**

- Visible/Infrared Imager Radiometer Suite (VIIRS)
**          **Raytheon Santa Barbara** ****Prototype in assembly/qual, flight unit in production**
- 0.4 km imaging and 0.8 km radiometer resolution
- 22 spectral bands covering 0.4 to 12.5 m
- Automatic dual VNIR and triple DNB gains
- Spectrally and radiometrically calibrated
- EDR-dependent swath widths of 1700, 2000, and 3000 km
- Crosstrack Infrared Sounder (CrIS)
**ITT Ft Wayne** Prototype in qualification, flight unit in production
- 158 SWIR (3.92 to 4.64 m) channels
- 432 MWIR (5.71 to 8.26 m) channels
- 711 LWIR (9.14 to 15.38 m) channels
- 3x3 detector array with 15 km ground center-to-center
- 2200 km swath width
- Advanced Technology Microwave Sounder (ATMS) - NASA
-         Northrop Grumman Electronics** ****Flight unit in qualification**
- CrIS companion cross track scan
- Profiling at 23, 50 to 57, 183 GHz
- Surface measurements at 31.4, 88, 165 GHz
- 1.1, 3.3, and 5.2 deg (SDRs resampled)
- 2300 km swath width
- Ozone Mapping and Profiler Suite (OMPS)
**      **Ball Aerospace** ****Flight unit in production**
- Total ozone column 300 to 380 nm with 1.0 nm resolution
- Nadir ozone profile 250 to 310 nm with 1.0 nm resolution
- Limb ozone profile 290 to 1000 nm with 2.4 to 54 nm resolution
- Swath width of 2800 km for total column

## Slide 29