Building an Integrated Ocean Color Sensor Web at the Land-Sea Interface UCSC UARC/ARC Ames GSFC BSI SARP

1. The primary geophysical data product(s) they are responsible for, e.g., the normalized water-leaving radiance, denoted here as [Lw]n. 2. The governing equation to produce the geophysical data product(s), e.g., [Lw]n = Fo*[0.54*Lu(0-)/Es]. 3. The measurements used to produce the primary data product(s), e.g., Lu, Ed, and Es (or Li, Lt, and Es). 4. The corrections applied to the measurements, e.g., self-shading, bidirectionality, Earth-Sun distance, etc. 5. Objective constraints applied during the data processing scheme, e.g., tilt filtering, Es normalization, Es convergence, etc. 6. Subjective constraints applied during the data processing scheme, e.g., determination of an extrapolation interval, etc. 7. The laboratory characterizations of the instruments, e.g., NIST-traceable calibration, immersion factor, stray light, etc. 8. The field characterizations of the instruments, e.g., dark currents, pressure tares, etc. 9. The uncertainty in the data product under the usual data sampling conditions, e.g., clear sky. 10. The publication(s) that document the protocols for laboratory characterizations, data acquisition, data processing, etc.

WET Labs ac-s 25 cm absorption (a) and attenuation (c) meter ~100 m depth rating, descent rate ~ 0.5 m/s Connected to dedicated SeaBird MicroCAT CTD nm, 4 nm resolution 4 Hz sampling rate Accuracy from.001 – 10 m -1 (depends on wavelength) 1)Primary geophysical parameters: spectral absorption and attenuation (m -1 ) 2)Primary Products: same (can be deployed with a filter to get CDOM but we don’t usually do that because of time constraints)

WET Labs ac-s Corrections: – Clean-water calibration – Water temperature and salinity corrections – Reflective tube scattering correction – Offset between gratings corrected – Data binned to depth (typically 0.5 m) – Generally use down-cast only

WET Labs ac-s Objective Constraints: – Various corrections applied – Absorption compared to discrete CDOM measurements – Does not require ambient light Subjective Constraints: – Grating offset – Comparison of data with “expected” values

WET Labs ac-s Lab Characterization – Vendor calibration/maintenance – Thermal correction, spectral corrections from CAL files – Air and pure water calibration Field Characterization – Deploy to 10 m, bring to surface (bubble purge) – Deploy at ~0.5 m/s (higher resolution) – Can let sit at a fixed depth to time-average data – Air Calibration (basically useless) – Water calibration daily

WET Labs ac-s Uncertainty – Data quality questionable below ~450 nm and strongly temperature dependent above ~600 nm – Calibration errors, drift, fouling of tubes, bubbles – 25 cm pathlength is ideal for Case 1, can lead to errors in highly turbid or high-biomass waters – No Attenuation Acceptance Angle correction – Sensitive to abrupt changes in T, S Publications – Manuals from WET Labs – Many (many) peer-reviewed publications – We generally follow the protocols developed by NRL