| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | August 14, 2013 |
| Latest Amendment Date: | June 25, 2018 |
| Award Number: | 1333425 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Kandace Binkley
kbinkley@nsf.gov (703)292-7577 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | February 1, 2014 |
| End Date: | July 31, 2019 (Estimated) |
| Total Intended Award Amount: | $1,196,338.00 |
| Total Awarded Amount to Date: | $1,369,807.00 |
| Funds Obligated to Date: |
FY 2015 = $403,162.00 FY 2017 = $135,000.00 FY 2018 = $38,469.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
400 HARVEY MITCHELL PKY S STE 300 COLLEGE STATION TX US 77845-4375 (979)862-6777 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
400 Harvey Mitchell Pkw Ste 300 College Station TX US 77845-4375 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | OCEAN TECH & INTERDISC COORDIN |
| Primary Program Source: |
01001516DB NSF RESEARCH & RELATED ACTIVIT 01001718DB NSF RESEARCH & RELATED ACTIVIT 01001819DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The PIs request funding to develop a new instrumentation for the measurement of the backscattering coefficient bb and the total scattering b. The proposed work will lead to new instrumentation that will provide the first single direct measurement of bb without any a priori assumptions about the phase function. The combined bb and b meter will provide unparalleled accuracy in determining the optical scattering and backscattering coefficients. These are very important parameters for remote sensing and for in-water bio-optical applications. This relatively simple instrument can be expected to have a transformative impact on optical measurements in the ocean and will be able to shed new light on the nature and distribution of scattering particulates.
Broader Impacts:
The activity stands an excellent chance of producing instrumentation that will allow the discovery and exploration of new effects and increase our understanding. This instrumentation has the potential of being sufficiently compact reliable and low power to be used in autonomous underwater vehicles and diving drifting buoys. Operating this new instrument from such platforms will produce a flood of previously unavailable data whose analysis can be the subject of both under-graduate and graduate research work. Working with information at the edge of a field, such as the one that could be produced by this new system, is the best of teaching tools, extremely rewarding and a real self-confidence and self-esteem builder for students. In summary I fully concur with the impact statement in the proposal. The proposal includes funds for a postdoc, graduate student, and undergraduate student.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
For decades, simple instrumentation to obtain bb and b have been pursued. However, for bb, the best available instruments rely on the accuracy of an empirical relation between measurements taken at specific angles and the total backscattering coefficient. Resulting data are operationally thought to have typical accuracy of ~5% and rely on assuming a universal shape for the phase function in natural waters. For b, the current state-of-the-art is a derivation from ancillary measurements of attenuation and absorption made with a WET Labs ac9 device. However, both of these measurements have significant errors due to acceptance angle effects for attenuation (typically >30%) and scattering error effects for absorption (typically >20%). The instrument developed in this project achieves measurement of these parameters with potential accuracies of better than 1%. Since measurements of bb and b are critical for ocean monitoring applications from satellite remote sensing and autonomous sampling methods (e.g., profiling floats and gliders), the new instrumentation has great potential to dramatically improve the ocean monitoring capabilities of the science community.
An important aspect of the bb instrumentation was development of the capability to measure light incident on the aperture at any angle from 0˚ to 90˚ with respect to the normal to the aperture, and to obtain those measurements with a constant efficiency independent of the angle of incidence. This instrumentation achieves that by using a slight depression in the aperture window surface and collecting the transmitted light via an integrating cavity. At the quartz/water interface in this instrument, the slight depression in the aperture window provides a transmission efficiency to the detector of 99.8%?0.06% over the full range of angles of incidence. Note, the ?0.06% or 6 parts in 10,000 is not an error, but rather it represents the extremes of the variation of the transmission efficiency over the full range of angles of incidence, 0? to 90?.
As an ancillary part of this work, the high efficiency diffuse reflector developed during this project was used in an integrating cavity to make the first reliable measurements of the absorption coefficient for pure water in the ultraviolet; at the minimum near 340 nm, the absorption coefficient for pure water is ~0.001 m-1 !
Last Modified: 12/28/2019
Modified by: Edward S Fry
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