SeaWiFS technical report series. Volume 5: Ocean optics protocols for SeaWiFS validation

Protocols are presented for measuring optical properties, and other environmental variables, to validate the radiometric performance of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), and to develop and validate bio-optical algorithms for use with SeaWiFS data. The protocols are intended to establish foundations for a measurement strategy to verify the challenging SeaWiFS accuracy goals of 5 percent in water-leaving radiances and 35 percent in chlorophyll alpha concentration. The protocols first specify the variables which must be measured, and briefly review rationale. Subsequent chapters cover detailed protocols for instrument performance specifications, characterizing and calibration instruments, methods of making measurements in the field, and methods of data analysis. These protocols were developed at a workshop sponsored by the SeaWiFS Project Office (SPO) and held at the Naval Postgraduate School in Monterey, California (9-12 April, 1991). This report is the proceedings of that workshop, as interpreted and expanded by the authors and reviewed by workshop participants and other members of the bio-optical research community. The protocols are a first prescription to approach unprecedented measurement accuracies implied by the SeaWiFS goals, and research and development are needed to improve the state-of-the-art in specific areas. The protocols should be periodically revised to reflect technical advances during the SeaWiFS Project cycle

Re-examining the effect of door-to-balloon delay on STEMI outcomes in the context of unmeasured confounders: a retrospective cohort study

Literature studying the door-to-balloon time-outcome relation in coronary intervention is limited by the potential of residual biases from unobserved confounders. This study re-examines the time-outcome relation with further consideration of the unobserved factors and reports the population average effect. Adults with ST-elevation myocardial infarction admitted to one of the six registry participating hospitals in Australia were included in this study. The exposure variable was patient-level door-to-balloon time. Primary outcomes assessed included in-hospital and 30 days mortality. 4343 patients fulfilled the study criteria. 38.0% (1651) experienced a door-to-balloon delay of >90 minutes. The absolute risk differences for in-hospital and 30-day deaths between the two exposure subgroups with balanced covariates were 2.81 (95% CI 1.04, 4.58) and 3.37 (95% CI 1.49, 5.26) per 100 population. When unmeasured factors were taken into consideration, the risk difference were 20.7 (95% CI −2.6, 44.0) and 22.6 (95% CI −1.7, 47.0) per 100 population. Despite further adjustment of the observed and unobserved factors, this study suggests a directionally consistent linkage between longer door-to-balloon delay and higher risk of adverse outcomes at the population level. Greater uncertainties were observed when unmeasured factors were taken into consideration

Water clarity meter. Operating and maintenance instructions

SIO Reference 59-9. The Watar Clarity Meter  has as its purpose the measurement of those optxeal properties of natural ocean waters which will permit   the determination of the optical clarity of these waters in the visible' portion of the spectrum. It is essential that at least two properties be measured to allow the determination of the transmittance of optical signals through the water (i.e., the contrast transmittance). The properties which were selected m this instance are the attenuation coefficient for collimated light, and the attenuation coefficient for diffuse (ambient) light

Water clarity meter. Operating and maintenance instructions

SIO Reference 59-9. The Watar Clarity Meter  has as its purpose the measurement of those optxeal properties of natural ocean waters which will permit   the determination of the optical clarity of these waters in the visible' portion of the spectrum. It is essential that at least two properties be measured to allow the determination of the transmittance of optical signals through the water (i.e., the contrast transmittance). The properties which were selected m this instance are the attenuation coefficient for collimated light, and the attenuation coefficient for diffuse (ambient) light

Water clarity meter. Operating and maintenance instructions

SIO Reference 59-9. The Watar Clarity Meter  has as its purpose the measurement of those optxeal properties of natural ocean waters which will permit   the determination of the optical clarity of these waters in the visible' portion of the spectrum. It is essential that at least two properties be measured to allow the determination of the transmittance of optical signals through the water (i.e., the contrast transmittance). The properties which were selected m this instance are the attenuation coefficient for collimated light, and the attenuation coefficient for diffuse (ambient) light

The index of refraction of seawater

SIO Reference 76-1. ft smoothly varying and internally self-consistent set of tables of the index of refraction of seawater with respect to air are presented. The dependence of the index on salinity (0 to 43°/00), temperature (0 to 30°C), wavelength(400 to 700 nm) and pressure (0 to 1100 kg/cm2 gage) has been fully covered. The relevant literature from prior to 1900 through the present has been extensively reviewed. Various comparisons between indices obtained from these sources and the tables presented have been performed suggesting an overall accuracy of the tabulated index values of about 3 x 10~s at atmospheric pressure and 1 x 10~4 at higher pressures. The extreme values encountered were 1.32921 and 1.36844, while the average slopes of the index surface, over the range of the variables considered, are An/As « 0.009/43°/00, An /At« - 0.002/30°C, An/AA« -0.013/300 nm, An/Ap« 0.015/1100 kg/cm2. Three dimensional diagrams provide complete views of the index of refraction surface.The requirements necessary for obtaining salinity and specific gravity directly from measurements of the index of refraction, for oceanographic purposes have been examined

The Index of Refraction of Seawater

SIO Reference 76-1. ft smoothly varying and internally self-consistent set of tables of the index of refraction of seawater with respect to air are presented. The dependence of the index on salinity (0 to 43°/00), temperature (0 to 30°C), wavelength(400 to 700 nm) and pressure (0 to 1100 kg/cm2 gage) has been fully covered. The relevant literature from prior to 1900 through the present has been extensively reviewed. Various comparisons between indices obtained from these sources and the tables presented have been performed suggesting an overall accuracy of the tabulated index values of about 3 x 10~s at atmospheric pressure and 1 x 10~4 at higher pressures. The extreme values encountered were 1.32921 and 1.36844, while the average slopes of the index surface, over the range of the variables considered, are An/As « 0.009/43°/00, An /At« - 0.002/30°C, An/AA« -0.013/300 nm, An/Ap« 0.015/1100 kg/cm2. Three dimensional diagrams provide complete views of the index of refraction surface.The requirements necessary for obtaining salinity and specific gravity directly from measurements of the index of refraction, for oceanographic purposes have been examined

Submarine visibility and related ambient light studies

SIO Reference 63-32. The major effort which was undertaken during the one-year period of the contract was to provide requested support for two field operations whose purpose was the study of the visibility of submarines from aircraft. Neither of these operations were successful in providing the primary information which was being sought due mostly to the vagaries of the weather and the Cuban blockade. Recommendations are given for a .plan for a future operation with more carefully controlled conditions and more restricted and specific objectives

Spectral dependence of the diffuse attenuation coefficient of light in ocean waters: a reexamination using new data

A model devised earlier1,2 relating the spectral dependence of K(.), the attenuation coefficient for natural diffuse light in the ocean, to the value of K()) at a reference wavelength, is re-examined using recently acquired data. The original model was based on data obtained from 1 967 to 1 979 by various investigators using a variety of scanning submersible spectroradiometers in tropical to mid-latitude waters. New data were obtained by the Visibility Laboratory in a series of cruises from 1985 to 1987 covering ocean latitudes from 24.4° to 77.4°. These data are believed to be of uniformly high quality and have the advantage over the previous data in that they permit the determination of K()) profiles to 200 meters from data obtained simultaneously at all 12 wavelengths and over a time span of approximately 6 minutes, vice data recorded serially at each wavelength and at discrete depths over a time span of as much as one to two hours with the spectroradiometers. An examination of the variation in the spectral K(A)'s with latitude was prompted by a concern that the phytoplankton species distribution at high latitudes might differ sufficiently from that at tropical to mid-latitudes to require a change in the spectral K(.\) model. A comparison was also performed between 83 sets of spectral K(A)'s derived from the new data and K(X)'s predicted by the model using measured K(490) as an input index. Small systematic differences were found which are not believed to be significant for most applications, hence, no change in the model is recommended on the basis of these findings