Status of MOBY and Future Plans

Dennis ClarkCarol Johnson, NISTSteve Brown, NIST

Mark Yarbrough, MLMLStephanie Flora, MLMLMike Feinholz, MLML

Present

• Competed nine years of observations - 8.5 years of continuous observations

• Recycle Deployment 31/32 December 2005

• Next Cycle scheduled for Feb./Mar. 2006– Annual mooring replacement – R2O mooring test scheduled

SeaWiFS Series

Processing Status1) Complete reprocessing of all old and new

MOBY deployments which included...• Quality Checking• Thermal Corrections• Pre and Post system responses merged• Straylight corrections• Eliminated the times of the dark scan measurements in the

computation of the average time for Lu/Es/Ed• Modis/Aqua was processed with project’s new RSR's• Added the solar normalized water leaving radiance (Lwn2)

which uses the Fo/Es formulation

• This reprocessing was completed in Feb 2005

Processing Status- continued

Project Requests:1) To reprocessed MOBY202 for OCTS -

Completed June 16

2) The MODIS Land bands were included in the MOBY processing and all old and new deployments computed with in-band satellite RSR’s. Sept 30

Work in Progress

1) Apply Gonio Corrections to Es data 2) Correct the Es data to Lu Times (should

improve the Lwn2)3) A working shadowing correction model4) Added actual ozone and pressure data for

the Lwn calculation5) Finish the pre/post cal evaluations for

MOBY 229- to present. 6) Evaluating the time-series for trends.

“Future”MOBY can probably keep going for another 3-

4 yrs based on exsisting spare parts.

Currently (FY05) Research to Operations Funding (R2O) for MOBY Redesign

Goals are:

• Transition MOBY vicarious calibration capabilities for NPP/NPOESS (e.g., VIIRS)

• Adapt MOBY technology for complex coastal validation activities for GOES-R (e.g. HES)

Currently Concentrating on 2 issues:

– Relocate power generation to mooring buoy• raised a transfer of power issue but enables a

reduction in size of optical buoy & associated deployment/servicing costs

– Simultaneous measurements to reduce environmental sources of measurement uncertainty, system complexity

• required a new optical system design

Tether Redesign and Prototype

• Electromechanical swivel– design compete, connectors specified, swivel order in

progress

• Tether flounder plate– preliminary mechanical design complete, strain relief

design in progress

• Electromechanical tether– final design complete, majority of components

ordered

• Guard Buoy service loop– design in progress

Tether Testing

Optical System Goals

• In MOBY, the scans are discrete and sequential; in the new system, they are simultaneous

• MOBY requires 20 min for upwelling radiance measurements (multiple Es and Lu scans). This is a undesirable sampling feature. There can be variability due to changing solar zenith angle and atmospheric conditions, requiring normalization procedures that introduce measurement uncertainty.

• The new system eliminates this problem by simultaneous observations with multiple inputs. In addition, a comparable sequence as for MOBY takes about 20 sec, not 20 min.

Instrument Layout, at Sea Testing

Optical System Breadboard• ISA f/2 spectrograph• Andor 1024x256 cooled CCD array• Four separate optical fiber inputs along

entrance slit

Lens, aperture, & shutter

CCD & spectrograph

Fiber bundle

Input fibers

Shutter drive circuit

Lens, aperture, & shutter

CCD & spectrograph

Fiber bundle

Input fibers

Shutter drive circuit

Spectralon sphere

Input fibers

Spectralon sphere

Input fibers

Breadboard System Performed Well

Spectral stray light from optical system is better than MOBY Stability, system response, and signal to

noise ratio adequate for ocean color measurements.

Successful Correction for Spectral and Spatial Stray Light

At Sea TestsThe breadboard system was implemented with four inputs and tested in Case 1 waters off Oahu in August 2005. The inputs were Es, Eu, Lu (0.75m) and Lu (3.25 m).

Preliminary Conclusions

• Breadboard System– Superior stray light (compared to MOBY)– A simple 2D stray light model was implemented– Satisfactory dynamic range and sensitivity– Successfully balanced individual throughputs resulting

in the same integration time, independent of Es or Lu• All fiber optical input simplifies optical design• Outstanding issues:

– Desirable to have six or eight fiber inputs– Increased spectral resolution– Prototype procurement