Aircraft and in Situ Salinity and Ocean Color Measurements and Comparisons in the Gulf of Mexico

The satellite validation navy tool (SAVANT) was developed by the Naval Research Laboratory to help facilitate the assessment of the stability and accuracy of ocean color satellites, using numerous ground truth (in situ) platforms around the globe and support methods for match-up protocols. The effects of varying spatial constraints with permissive and strict protocols on match-up uncertainty are evaluated, in an attempt to establish an optimal satellite ocean color calibration and validation (cal/val) match-up protocol. This allows users to evaluate the accuracy of ocean color sensors compared to specific ground truth sites that provide continuous data. Various match-up constraints may be adjusted, allowing for varied evaluations of their effects on match-up data. The results include the following: (a) the difference between aerosol robotic network ocean color (AERONET-OC) and marine optical Buoy (MOBY) evaluations; (b) the differences across the visible spectrum for various water types; (c) spatial differences and the size of satellite area chosen for comparison; and (d) temporal differences in optically complex water. The match-up uncertainty analysis was performed using Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) SNPP data at the AERONET-OC sites and the MOBY site. It was found that the more permissive constraint sets allow for a higher number of match-ups and a more comprehensive representation of the conditions, while the restrictive constraints provide better statistical match-ups between in situ and satellite sensors.

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Influence of frontal cyclone evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current eddy detachment events

Ocean Science ◽

10.5194/os-10-947-2014 ◽

2014 ◽

Vol 10 (6) ◽

pp. 947-965 ◽

Cited By ~ 5

Author(s):

Y. S. Androulidakis ◽

V. H. Kourafalou ◽

M. Le Hénaff

Keyword(s):

Numerical Simulation ◽

Gulf Of Mexico ◽

Satellite Data ◽

Potential Vorticity ◽

In Situ Measurements ◽

Loop Current ◽

Positive Potential ◽

Eastern Gulf Of Mexico ◽

And Migration

Abstract. The anticyclonic Loop Current Eddy (LCE) shedding events are strongly associated with the evolution of Loop Current Frontal Eddies (LCFEs) over the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ measurements and satellite data, was used to investigate the Loop Current (LC) evolution and the surrounding LCFE formation, structure, growth and migration during the Eddy Ekman and Eddy Franklin shedding events in the summers of 2009 and 2010, respectively. During both events, northern GoM LCFEs appeared vertically coherent to at least 1500 m in temperature observations. They propagated towards the base of the LC, where, together with the migration of Campeche Bank (southwest GoM shelf) eddies from south of the LC, contributed to its "necking-down". Growth of Campeche Bank LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank waters following upwelling events. Slope processes associated with such upwelling included offshore exports of high positive potential vorticity that may trigger cyclone formation and growth. The advection and growth of LCFEs, originating from the northern and southern GoM, and their interaction with the LC over the LCE detachment area favor shedding conditions and may contribute to the final separation of the LCE.

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Comparison of in situ and columnar aerosol spectral measurements during TexAQS-GoMACCS 2006: testing parameterizations for estimating aerosol fine mode properties

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-17465-2009 ◽

2009 ◽

Vol 9 (4) ◽

pp. 17465-17494

Author(s):

D. B. Atkinson ◽

P. Massoli ◽

N. T. O'Neill ◽

P. K. Quinn ◽

S. Brooks ◽

...

Keyword(s):

Gulf Of Mexico ◽

Atmospheric Aerosols ◽

Regional Scale ◽

Atmospheric Composition ◽

Light Extinction ◽

Large Area ◽

Light Extinction Coefficient ◽

Spectral Models ◽

Fine Mode

Abstract. During the 2006 Texas Air Quality Study and Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS 2006), the optical, chemical and microphysical properties of atmospheric aerosols were measured on multiple mobile platforms and at ground based stations. In situ measurements of the aerosol light extinction coefficient (σep) were performed by two multi-wavelength cavity ring-down (CRD) instruments, one located on board the NOAA R/V Ronald H. Brown (RHB) and the other located at the University of Houston, Moody Tower (UHMT). An AERONET sunphotometer was also located at the UHMT to measure the columnar aerosol optical depth (AOD). The σep data were used to extract the extinction Ångström exponent (åep), a measure of the wavelength dependence of σep. There was general agreement between the åep (and to a lesser degree σep measurements by the two spatially separated CRD instruments during multi-day periods, suggesting a regional scale consistency of the sampled aerosols. Two spectral models are applied to the σep and AOD data to extract the fine mode fraction of extinction (η) and the fine mode effective radius (Reff f). These two parameters are robust measures of the fine mode contribution to total extinction and the fine mode size distribution respectively. The results of the analysis are compared to Reff f values extracted using AERONET V2 retrievals and calculated from in situ particle size measurements on the RHB and at UHMT. During a time period when fine mode aerosols dominated the extinction over a large area extending from Houston/Galveston Bay and out into the Gulf of Mexico, the various methods for obtaining Reff f agree qualitatively (showing the same temporal trend) and quantitatively (pooled standard deviation=28 nm).

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Comparison of Above-Water Seabird and TriOS Radiometers along an Atlantic Meridional Transect

Remote Sensing ◽

10.3390/rs12101669 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1669

Author(s):

Krista Alikas ◽

Viktor Vabson ◽

Ilmar Ansko ◽

Gavin H. Tilstone ◽

Giorgio Dall’Olmo ◽

...

Keyword(s):

State Of The Art ◽

Ocean Color ◽

Percentage Difference ◽

Wide Range ◽

Before And After ◽

Reference Measurements ◽

Satellite Ocean Color ◽

Good Agreement

The Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) project has carried out a range of activities to evaluate and improve the state-of-the-art in ocean color radiometry. This paper described the results from a ship-based intercomparison conducted on the Atlantic Meridional Transect 27 from 23rd September to 5th November 2017. Two different radiometric systems, TriOS-Radiation Measurement Sensor with Enhanced Spectral resolution (RAMSES) and Seabird-Hyperspectral Surface Acquisition System (HyperSAS), were compared and operated side-by-side over a wide range of Atlantic provinces and environmental conditions. Both systems were calibrated for traceability to SI (Système international) units at the same optical laboratory under uniform conditions before and after the field campaign. The in situ results and their accompanying uncertainties were evaluated using the same data handling protocols. The field data revealed variability in the responsivity between TRiOS and Seabird sensors, which is dependent on the ambient environmental and illumination conditions. The straylight effects for individual sensors were mostly within ±3%. A near infra-red (NIR) similarity correction changed the water-leaving reflectance (ρw) and water-leaving radiance (Lw) spectra significantly, bringing also a convergence in outliers. For improving the estimates of in situ uncertainty, it is recommended that additional characterization of radiometers and environmental ancillary measurements are undertaken. In general, the comparison of radiometric systems showed agreement within the evaluated uncertainty limits. Consistency of in situ results with the available Sentinel-3A Ocean and Land Color Instrument (OLCI) data in the range from (400…560) nm was also satisfactory (−8% < Mean Percentage Difference (MPD) < 15%) and showed good agreement in terms of the shape of the spectra and absolute values.

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Use of Microautoradiography Combined with Fluorescence In Situ Hybridization To Determine Dimethylsulfoniopropionate Incorporation by Marine Bacterioplankton Taxa

Applied and Environmental Microbiology ◽

10.1128/aem.70.8.4648-4657.2004 ◽

2004 ◽

Vol 70 (8) ◽

pp. 4648-4657 ◽

Cited By ~ 70

Author(s):

Maria Vila ◽

Rafel Simó ◽

Ronald P. Kiene ◽

Jarone Pinhassi ◽

José M. González ◽

...

Keyword(s):

In Situ Hybridization ◽

Gulf Of Mexico ◽

Fluorescence In Situ Hybridization ◽

Marine Bacteria ◽

Heterotrophic Bacteria ◽

Phytoplankton Bloom ◽

Mediterranean Coast ◽

Marine Bacterioplankton ◽

Significant Uptake

ABSTRACT The fraction of planktonic heterotrophic bacteria capable of incorporating dissolved dimethylsulfoniopropionate (DMSP) and leucine was determined at two coastal sites by microautoradioagraphy (AU). In Gulf of Mexico seawater microcosm experiments, the proportion of prokaryotes that incorporated sulfur from [35S]DMSP ranged between 27 and 51% of 4′,6-diamidino-2-phenylindole (DAPI)-positive cells, similar to or slightly lower than the proportion incorporating [3H]leucine. In the northwest Mediterranean coast, the proportion of cells incorporating sulfur from [35S]DMSP increased from 5 to 42% from January to March, coinciding with the development of a phytoplankton bloom. At the same time, the proportion of cells incorporating [3H]leucine increased from 21 to 40%. The combination of AU and fluorescence in situ hybridization (FISH) revealed that the Roseobacter clade (α-proteobacteria) accounted for 13 to 43% of the microorganisms incorporating [35S]DMSP at both sampling sites. Significant uptake of sulfur from DMSP was also found among members of the γ-proteobacteria and Cytophaga-Flavobacterium groups. Roseobacter and γ-proteobacteria exhibited the highest percentage of DAPI-positive cells incorporating 35S from DMSP (around 50%). Altogether, the application of AU with [35S]DMSP combined with FISH indicated that utilization of S from DMSP is a widespread feature among active marine bacteria, comparable to leucine utilization. These results point toward DMSP as an important substrate for a broad and diverse fraction of marine bacterioplankton.

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Evaluation of ocean color and sea surface temperature sensors algorithms using in situ data: a case study of temporal and spatial variability on two northeast Atlantic seamounts

Journal of Applied Remote Sensing ◽

10.1117/1.3328872 ◽

2010 ◽

Vol 4 (1) ◽

pp. 043506 ◽

Cited By ~ 10

Author(s):

Ana Mendonca

Keyword(s):

Spatial Variability ◽

Surface Temperature ◽

Ocean Color ◽

Temperature Sensors ◽

Sea Surface ◽

In Situ Data ◽

Temporal And Spatial Variability ◽

Temporal And Spatial

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Examination of AVO responses in the eastern deepwater Gulf of Mexico

Geophysics ◽

10.1190/1.1487130 ◽

2001 ◽

Vol 66 (6) ◽

pp. 1864-1876 ◽

Cited By ~ 6

Author(s):

Tad M. Smith ◽

Carl H. Sondergeld

Keyword(s):

Gulf Of Mexico ◽

Oil And Gas ◽

Shear Velocity ◽

Bright Spot ◽

Velocity Data ◽

Amplitude Variation ◽

Amplitude Variation With Offset ◽

Saturated Sands ◽

Local Shear

Exploration programs in deepwater Tertiary basins (e.g., the Gulf of Mexico) typically rely on bright‐spot and amplitude variation with offset (AVO) technology to help identify oil‐ and gas‐charged sands. The reliance on these attributes, along with the high cost of exploration programs in deepwater environments, has driven the need to examine the limitations of these technologies and to build robust models for the conditions under which AVO is useful as a fluid and/or lithology indicator. We build subregional AVO background trends for both brine‐ and gas‐saturated sands from several wells from the eastern deepwater Gulf of Mexico. These trends are built from the depth dependencies of velocities and densities for both shale and sands (brine saturated). Simple models of AVO gradient and intercept are constructed as a function of depth below the mud line. Sand and shale properties show little velocity contrast, justifying the interpretation of these data in the context of linearized AVO models. In addition to the in‐situ brine response, the response to gas is also calculated. These trend models indicate that the AVO response is suppressed (although still positive) below a depth of approximately 10 000 ft below the mud line. Even optimistic porosity modeling (sand porosity >30°) does not substantially change this conclusion. An important corollary is that the absence of a strong AVO anomaly at these deeper depths cannot be used with confidence when ruling out hydrocarbon presence. This observation also highlights the need to crossplot attributes to best predict hydrocarbon presence. Velocity data collected as part of this study are also used to generate a local shear velocity estimator for sands and shale. These shear estimators are similar in form to other published estimators, but minor differences in coefficients may become important in AVO modeling.

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