Bigorre Sebastien P.

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Bigorre

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Sebastien P.

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The Northwest Tropical Atlantic Station (NTAS): NTAS-18 Mooring Turnaround Cruise Report Cruise On Board RV Ronald H. Brown January 6 –26, 2020 Bridgetown, Barbados – Bridgetown, Barbados

(Woods Hole Oceanographic Institution, 2021-02-24) Bigorre, Sebastien P. ; Pietro, Benjamin ; Hasbrouck, Emerson

The Northwest Tropical Atlantic Station (NTAS) was established to address the need for accurate air-sea flux estimates and upper ocean measurements in a region with strong sea surface temperature anomalies and the likelihood of significant local air–sea interaction on interannual to decadal timescales. The approach is to maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 15°N, 51°W by successive mooring turnarounds. These observations are used to investigate air–sea interaction processes related to climate variability. The NTAS Ocean Reference Station (ORS NTAS) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Global Ocean Monitoring and Observing (GOMO) Program (formerly Ocean Observing and Monitoring Division). This report documents recovery of the NTAS-17 mooring and deployment of the NTAS-18 mooring at the same site. Both moorings used Surlyn foam buoys as the surface element. These buoys were outfitted with two Air–Sea Interaction Meteorology (ASIMET) systems. Each system measures, records, and transmits via satellite the surface meteorological variables necessary to compute air–sea fluxes of heat, moisture and momentum. The upper 160 m of the mooring line were outfitted with oceanographic sensors for the measurement of temperature, salinity and velocity. The mooring turnaround was done by the Upper Ocean Processes Group of the Woods Hole Oceanographic Institution (WHOI), onboard R/V Ron Brown, Cruise RB-20-01. The cruise took place between January 6 and 26 2020. The NTAS-18 mooring was deployed on January 10, and the NTAS-17 mooring was recovered on January 15. Inter-comparison between ship and buoys were performed on this cruise. This report describes these operations, as well as other work done on the cruise and some of the pre-cruise buoy preparations. Other operations during RB-20-01 consisted in the acoustic communications with the Meridional Overturning Variability Experiment (MOVE) subsurface mooring array MOVE 1-13 and acoustic downloads of data from Pressure Inverted Echo Sounders (PIES) was also conducted at MOVE 1. MOVE is designed to monitor the integrated deep meridional flow in the tropical North Atlantic. Two ARGO floats were also deployed on behalf of the WHOI ARGO group. During the cruise, atmospheric measurements of aerosols, as well as radar, Lidar, radiosondes were made as part of the ATOMIC campaign. 3
CLIVAR Mode Water Dynamics Experiment (CLIMODE) fall 2005, R/V Oceanus voyage 419, November 9, 2005–November 27, 2005

(Woods Hole Oceanographic Institution, 2006-02) Hutto, Lara ; Weller, Robert A. ; Fratantoni, David M. ; Lord, Jeffrey ; Kemp, John N. ; Lund, John M. ; Brambilla, Elena ; Bigorre, Sebastien P.

CLIMODE (CLIVAR Mode Water Dynamic Experiment) is a program designed to understand and quantify the processes responsible for the formation and dissipation of North Atlantic subtropical mode water, also called Eighteen Degree Water (EDW). Among these processes, the amount of buoyancy loss at the ocean-atmosphere interface is still uncertain and needs to be accurately quantified. In November 2005, a cruise was made aboard R/V Oceanus in the region of the separated Gulf Stream, where intense oceanic heat loss to the atmosphere is believed to trigger the formation of EDW. During that cruise, one surface mooring with IMET meteorological instruments was anchored in the core of the Gulf Stream as well as two moored profilers on its southeastern edge. Surface drifters, APEX floats and bobby RAFOS floats were also deployed along with two other moorings with sound sources. CTD profiles and water samples were also carried out. This array of instruments will permit a characterization of EDW with high spatial and temporal resolutions, and accurate in-situ measurements of air-sea fluxes in the formation region. The present report documents this cruise, the instruments that were deployed and the array of measurements that was set in place.
Corrigendum : On the exchange of momentum over the open ocean

(American Meteorological Society, 2014-09) Edson, James B. ; Jampana, Venkata ; Weller, Robert A. ; Bigorre, Sebastien P. ; Plueddemann, Albert J. ; Fairall, Christopher W. ; Miller, Scott D. ; Mahrt, Larry ; Vickers, Dean ; Hersbach, Hans
UCTD and EM/APEX measurements in support of the April 2015 AirSWOT Campaign : cruise and data report

(Woods Hole Oceanographic Institution, 2015-12) Farrar, J. Thomas ; Hodges, Benjamin A. ; Bigorre, Sebastien P. ; Galbraith, Nancy R. ; Girton, James B. ; Chao, Yi

AirSWOT is an aircraft mounted instrument for measuring and imaging sea surface height (SSH), and it is similar to the SWOT (Surface Water Ocean Topography) instrument that will be deployed on a satellite in 2020. A field campaign was conducted in April 2015 to examine the performance of AirSWOT and to better understand how the measurement is affected by surface waves and currents. Supporting measurements were collected from the R/V Shana Rae, the R/V Fulmar, and a second aircraft (a Partenavia P68 operated by Aspen Helicopter, Oxnard,CA for UCSD/SIO). From 17-20 April 2015, the R/V Shana Rae, a 50-foot research vessel, was used for collection of Underway CTD (or UCTD) measurements and for deployment and recovery of three EM/APEX floats in a study area off the central California coast. The UCTD measurements are being used to estimate the sea surface height signal associated with variations in ocean density structure. The EM/APEX floats provide time series of the same, as well as vertical profiles of ocean velocity. The purpose of this report is to document the shipboard operations on the R/V Shana Rae and the resulting UCTD and EM/APEX data sets.
CLIVAR Mode Water Dynamics Experiment (CLIMODE) fall 2006 R/V Oceanus voyage 434 November 16, 2006–December 3, 2006

(Woods Hole Oceanographic Institution, 2007-12) Bigorre, Sebastien P. ; Weller, Robert A. ; Lord, Jeffrey ; Lund, John M. ; Palter, Jaime B. ; Tupper, George H.

CLIMODE (CLIVAR Mode Water Dynamic Experiment) is a research program designed to understand and quantify the processes responsible for the formation and dissipation of North Atlantic subtropical mode water, also called Eighteen Degree Water (EDW). Among these processes, the amount of buoyancy loss at the ocean-atmosphere interface is still uncertain and needs to be accurately quantified. In November 2006, cruise 434 onboard R/V Oceanus traveled in the region of the separated Gulf Stream and its recirculation, where intense oceanic heat loss to the atmosphere in the winter is believed to trigger the formation of EDW. During this cruise, the surface mooring F that was anchored in the core of the Gulf Stream was replaced by a new one, as well as two subsurface moorings C and D located on the southeastern edge of the stream. Surface drifters, ARGO and bobbers RAFOS floats were deployed, CTD profiles and water samples were also carried out. This array of instruments will permit a characterization of EDW with high spatial and temporal resolutions and accurate in-situ measurements of air-sea fluxes in the EDW formation region. The present report documents this cruise, the methods and locations for the deployments of instruments and some evaluation of the measurements from these instruments.
Stratus 11 : Eleventh Setting of the Stratus Ocean Reference Station Cruise on board RV Moana Wave, March 31 - April 16, 2011, Arica - Arica, Chile

(Woods Hole Oceanographic Institution, 2011-09) Bigorre, Sebastien P. ; Lord, Jeffrey ; Galbraith, Nancy R. ; Whelan, Sean P. ; Otto, William ; Holte, James W. ; Bariteau, Ludovic ; Weller, Robert A.

The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide ongoing climate-quality records of surface meteorology, air-sea fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Climate Observation Program. It is recovered and redeployed annually, with past cruises that have come between October and January. A NOAA vessel was not available, so this cruise was conducted on the chartered ship, Moana Wave, belonging to Stabbert Maritime. During the 2011 cruise on the Moana Wave to the ORS Stratus site, the primary activities were the recovery of the subsurface part of the Stratus 10 WHOI surface mooring, deployment of a new (Stratus 11) WHOI surface mooring, in-situ calibration of the buoy meteorological sensors by comparison with instrumentation installed on the ship by staff of the NOAA Earth System Research Laboratory (ESRL), and collection of underway and on station oceanographic data to continue to characterize the upper ocean in the stratus region. The Stratus 10 mooring had parted, and the surface buoy and upper part had been recovered earlier. Underway CTD (UCTD) profiles were collected along the track and during surveys dedicated to investigating eddy variability in the region. Surface drifters and subsurface floats were also launched along the track. The intent was also to visit a buoy for the Pacific tsunami warning system maintained by the Hydrographic and Oceanographic Service of the Chilean Navy (SHOA). This DART (Deep- Ocean Assessment and Reporting of Tsunami) buoy had been deployed in December 2010.
Stratus 10 tenth setting of the Stratus Ocean Reference Station : cruise RB-10-01, January 2 - January 30, 2010 Charleston, South Carolina - Valparaiso, Chile

(Woods Hole Oceanographic Institution, 2010-05) Bigorre, Sebastien P. ; Weller, Robert A. ; Lord, Jeffrey ; Galbraith, Nancy R. ; Whelan, Sean P. ; Zappa, Christopher J. ; Otto, William ; Ram, Jessica ; Vasquez, Raul ; Suhm, Diane

The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide ongoing climate-quality records of surface meteorology, air-sea fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Climate Observation Program. It is recovered and redeployed annually, with past cruises that have come between October and December. Due to necessary repairs on the electric motors of the ship’s propulsion system, this year the cruise was delayed until January. During the 2009/2010 cruise on the NOAA ship Ronald H. Brown to the ORS Stratus site, the primary activities were the recovery of the Stratus 9 WHOI surface mooring that had been deployed in October 2008, deployment of a new (Stratus 10) WHOI surface mooring at that site, in-situ calibration of the buoy meteorological sensors by comparison with instrumentation installed on the ship by staff of the NOAA Earth System Research Laboratory (ESRL), and collection of underway and on station oceanographic data to continue to characterize the upper ocean in the stratus region. Both underway CTD (UCTD) profiles and Vertical Microstructure Profiles (VMP) were collected along the track and during surveys dedicated to investigating eddy variability in the region. Surface drifters were also launched along the track. The intent was also to visit a buoy for the Pacific tsunami warning system maintained by the Hydrographic and Oceanographic Service of the Chilean Navy (SHOA). This DART (Deep- Ocean Assessment and Reporting of Tsunami) buoy had been equipped with IMET sensors and subsurface oceanographic instruments, and a recovery and replacement of the IMET sensors was planned. However, the DART buoy broke free from its mooring on January 3rd and was recovered by the Chilean navy; the work done at that site during this cruise was the recovery of the bottom pressure unit.
A surface mooring for air–sea interaction research in the Gulf Stream. Part I : mooring design and instrumentation

(American Meteorological Society, 2012-09) Weller, Robert A. ; Bigorre, Sebastien P. ; Lord, Jeffrey ; Ware, Jonathan D. ; Edson, James B.

The design of a surface mooring for deployment in the Gulf Stream in the Mid-Atlantic Bight is described. The authors' goals were to observe the surface meteorology; upper-ocean variability; and air–sea exchanges of heat, freshwater, and momentum in and near the Gulf Stream during two successive 1-yr deployments. Of particular interest was quantifying these air–sea fluxes during wintertime events that carry cold, dry air from the land over the Gulf Stream. Historical current data and information about the surface waves were used to guide the design of the surface mooring. The surface buoy provided the platform for both bulk meteorological sensors and a direct covariance flux system. Redundancy in the meteorological sensors proved to be a largely successful strategy to obtain complete time series. Oceanographic instrumentation was limited in size by considerations of drag; and two current meters, three temperature–salinity recorders, and 15 temperature recorders were deployed. Deployment from a single-screw vessel in the Gulf Stream required a controlled-drift stern first over the anchor sites. The first deployment lasted the planned full year. The second deployment ended after 3 months when the mooring was cut by unknown means at a depth of about 3000 m. The mooring was at times in the core of the Gulf Stream, and a peak surface current of over 2.7 m s−1 was observed. The 15-month records of surface meteorology and air–sea fluxes captured the seasonal variability as well as several cold-air outbreaks; the peak observed heat loss was in excess of 1400 W m−2.
Assessing the dynamics of organic aerosols over the North Atlantic Ocean

(Nature Publishing Group, 2017-03-31) Kasparian, Jerome ; Hassler, Christel ; Ibelings, Bastiaan ; Berti, Nicolas ; Bigorre, Sebastien P. ; Djambazova, Violeta ; Gascon Diez, Elena ; Giuliani, Grégory ; Houlmann, Raphaël ; Kiselev, Denis ; de Laborie, Pierric ; Le, Anh-Dao ; Magouroux, Thibaud ; Neri, Tristan ; Palomino, Daniel ; Pfändler, Stéfanie ; Ray, Nicolas ; Sousa, Gustavo ; Staedler, Davide ; Tettamanti, Federico ; Wolf, Jean-Pierre ; Beniston, Martin

The influence of aerosols on climate is highly dependent on the particle size distribution, concentration, and composition. In particular, the latter influences their ability to act as cloud condensation nuclei, whereby they impact cloud coverage and precipitation. Here, we simultaneously measured the concentration of aerosols from sea spray over the North Atlantic on board the exhaust-free solar-powered vessel “PlanetSolar”, and the sea surface physico-chemical parameters. We identified organic-bearing particles based on individual particle fluorescence spectra. Organic-bearing aerosols display specific spatio-temporal distributions as compared to total aerosols. We propose an empirical parameterization of the organic-bearing particle concentration, with a dependence on water salinity and sea-surface temperature only. We also show that a very rich mixture of organic aerosols is emitted from the sea surface. Such data will certainly contribute to providing further insight into the influence of aerosols on cloud formation, and be used as input for the improved modeling of aerosols and their role in global climate processes.
Measurements from the RV Ronald H. Brown and related platforms as part of the Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC)

(Copernicus Publications, 2021-04-29) Quinn, Patricia K. ; Thompson, Elizabeth ; Coffman, Derek J. ; Baidar, Sunil ; Bariteau, Ludovic ; Bates, Timothy S. ; Bigorre, Sebastien P. ; Brewer, Alan ; de Boer, Gijs ; de Szoeke, Simon P. ; Drushka, Kyla ; Foltz, Gregory R. ; Intrieri, Janet ; Iyer, Suneil ; Fairall, Christopher W. ; Gaston, Cassandra J. ; Jansen, Friedhelm ; Johnson, James E. ; Krüger, Ovid O. ; Marchbanks, Richard D. ; Moran, Kenneth P. ; Noone, David ; Pezoa, Sergio ; Pincus, Robert ; Plueddemann, Albert J. ; Pöhlker, Mira L. ; Pöschl, Ulrich ; Quinones Melendez, Estefania ; Royer, Haley M. ; Szczodrak, Malgorzata ; Thomson, Jim ; Upchurch, Lucia M. ; Zhang, Chidong ; Zhang, Dongxiao ; Zuidema, Paquita

The Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) took place from 7 January to 11 July 2020 in the tropical North Atlantic between the eastern edge of Barbados and 51∘ W, the longitude of the Northwest Tropical Atlantic Station (NTAS) mooring. Measurements were made to gather information on shallow atmospheric convection, the effects of aerosols and clouds on the ocean surface energy budget, and mesoscale oceanic processes. Multiple platforms were deployed during ATOMIC including the NOAA RV Ronald H. Brown (RHB) (7 January to 13 February) and WP-3D Orion (P-3) aircraft (17 January to 10 February), the University of Colorado's Robust Autonomous Aerial Vehicle-Endurant Nimble (RAAVEN) uncrewed aerial system (UAS) (24 January to 15 February), NOAA- and NASA-sponsored Saildrones (12 January to 11 July), and Surface Velocity Program Salinity (SVPS) surface ocean drifters (23 January to 29 April). The RV Ronald H. Brown conducted in situ and remote sensing measurements of oceanic and atmospheric properties with an emphasis on mesoscale oceanic–atmospheric coupling and aerosol–cloud interactions. In addition, the ship served as a launching pad for Wave Gliders, Surface Wave Instrument Floats with Tracking (SWIFTs), and radiosondes. Details of measurements made from the RV Ronald H. Brown, ship-deployed assets, and other platforms closely coordinated with the ship during ATOMIC are provided here. These platforms include Saildrone 1064 and the RAAVEN UAS as well as the Barbados Cloud Observatory (BCO) and Barbados Atmospheric Chemistry Observatory (BACO). Inter-platform comparisons are presented to assess consistency in the data sets. Data sets from the RV Ronald H. Brown and deployed assets have been quality controlled and are publicly available at NOAA's National Centers for Environmental Information (NCEI) data archive (https://www.ncei.noaa.gov/archive/accession/ATOMIC-2020, last access: 2 April 2021). Point-of-contact information and links to individual data sets with digital object identifiers (DOIs) are provided herein.
A surface mooring for air–sea interaction research in the Gulf Stream. Part II : analysis of the observations and their accuracies

(American Meteorological Society, 2013-03) Bigorre, Sebastien P. ; Weller, Robert A. ; Edson, James B. ; Ware, Jonathan D.

A surface mooring was deployed in the Gulf Stream for 15 months to investigate the role of air–sea interaction in mode water formation and other processes. The accuracies of the near-surface meteorological and oceanographic measurements are investigated. In addition, the impacts of these measurement errors on the estimation and study of the air–sea fluxes in the Gulf Stream are discussed. Pre- and postdeployment calibrations together with in situ comparison between shipboard and moored sensors supported the identification of biases due to sensor drifts, sensor electronics, and calibration errors. A postdeployment field study was used to further investigate the performance of the wind sensors. The use of redundant sensor sets not only supported the filling of data gaps but also allowed an examination of the contribution of random errors. Air–sea fluxes were also analyzed and computed from both Coupled Ocean–Atmosphere Response Experiment (COARE) bulk parameterization and using direct covariance measurements. The basic conclusion is that the surface buoy deployed in the Gulf Stream to support air–sea interaction research was successful, providing an improved 15-month record of surface meteorology, upper-ocean variability, and air–sea fluxes with known accuracies. At the same time, the coincident deployment of mean meteorological and turbulent flux sensors proved to be a successful strategy to certify the validity of the bulk formula fluxes over the midrange of wind speeds and to support further work to address the present shortcomings of the bulk formula methods at the low and high wind speeds.
EUREC4A : a field campaign to elucidate the couplings between clouds, convection and circulation

(Springer, 2017-09-27) Bony, Sandrine ; Stevens, Bjorn ; Ament, Felix ; Bigorre, Sebastien P. ; Chazette, Patrick ; Crewell, Susanne ; Delanoë, Julien ; Emanuel, Kerry A. ; Farrell, David ; Flamant, Cyrille ; Gross, Silke ; Hirsch, Lutz ; Karstensen, Johannes ; Mayer, Bernhard ; Nuijens, Louise ; Ruppert, James H. ; Sandu, Irina ; Siebesma, Pier ; Speich, Sabrina ; Szczap, Frédéric ; Totems, Julien ; Vogel, Raphaela ; Wendisch, Manfred ; Wirth, Martin

Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization.
The Northwest Tropical Atlantic Station (NTAS) : NTAS-15 Mooring Turnaround Cruise Report cruise on board RV Endeavor January 25 - February 13, 2016 Narragansett RI, USA - San Juan, Puerto Rico

(Woods Hole Oceanographic Institution, 2016-11) Bigorre, Sebastien P. ; Ryder, James R. ; Smith, Jason C. ; Lankhorst, Matthias ; Plueddemann, Albert

The Northwest Tropical Atlantic Station (NTAS) was established to address the need for accurate air-sea flux estimates and upper ocean measurements in a region with strong sea surface temperature anomalies and the likelihood of significant local air–sea interaction on interannual to decadal timescales. The approach is to maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 15°N, 51°W by successive mooring turnarounds. These observations are used to investigate air–sea interaction processes related to climate variability. The NTAS Ocean Reference Station (ORS NTAS) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Climate Observation Program. This report documents recovery of the NTAS-14 mooring and deployment of the NTAS-15 mooring at the same site. Both moorings used Surlyn foam buoys as the surface element. These buoys were outfitted with two Air–Sea Interaction Meteorology (ASIMET) systems. Each system measures, records, and transmits via Argos satellite the surface meteorological variables necessary to compute air–sea fluxes of heat, moisture and momentum. The upper 160 m of the mooring line were outfitted with oceanographic sensors for the measurement of temperature, salinity and velocity. The mooring turnaround was done by the Upper Ocean Processes Group of the Woods Hole Oceanographic Institution (WHOI), onboard R/V Endeavor, Cruise EN573. The cruise took place between January 25 and February 13 2016. The NTAS-15 mooring was deployed on February 2, and the NTAS-14 mooring was recovered on February 4. A 24-hour intercomparison period was conducted on February 5, during which data from the buoy, telemetered through Argos satellite system, and the ship’s meteorological and oceanographic data were monitored while the ship was stationed 0.2 nm downwind of NTAS-15 buoy. A similar procedure was done at NTAS-14 but for only about 10 hours on the morning of February 4. This report describes these operations, as well as other work done on the cruise and some of the precruise buoy preparations. Other operations during EN573 consisted in the recovery and deployment of the Meridional Overturning Variability Experiment (MOVE) subsurface moorings array (MOVE 1 in the east, and MOVE 3 and 4 in the west near Guadeloupe). Acoustic download of data from Pressure Inverted Echo Sounders (PIES) was also conducted. MOVE is designed to monitor the integrated deep meridional flow in the tropical North Atlantic.
The annual cycle of air-sea fluxes in the northwest tropical Atlantic

(Frontiers Media, 2021-01-15) Bigorre, Sebastien P. ; Plueddemann, Albert J.

In this article we analyze 11 years of near-surface meteorology using observations from an open-ocean surface mooring located in the Northwestern Tropical Atlantic (51°W, 15°N). Air-sea fluxes of heat, freshwater, and momentum are derived from these observations using the Coupled Ocean–Atmosphere Response Experiment (COARE) bulk parameterization. Using this dataset, we compute a climatology of the annual cycle of near-surface meteorological conditions and air-sea fluxes. These in situ data are then compared with three reanalyses: the National Centers for Environmental Prediction-Department of Energy [NCEP-DOE (hereafter referred to as NCEP-2)], the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim and the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalyses. Products from the Clouds and the Earth’s Radiant Energy System (CERES) and the Tropical Rainfall Measuring Mission (TRMM) are also used for comparison. We identify the agreements and characterize the discrepancies in the annual cycles of meteorological variables and the different components of air-sea heat fluxes (latent, sensible, shortwave, and longwave radiation). Recomputing the reanalyses fluxes by applying the COARE algorithm to the reanalyses meteorological variables results in better agreement with the in situ fluxes than using the reanalyses fluxes directly. However, the radiative fluxes (longwave and shortwave) from some of the reanalyses show significant discrepancies when compared with the in situ measurements. Longwave radiation from MERRA-2 is biased high (too much oceanic heat loss), and NCEP-2 longwave does not correlate to in situ observations and other reanalyses. Shortwave radiation from NCEP-2 is biased low in winter and does not track the observed variability in summer. The discrepancies in radiative fluxes versus in situ fluxes are explored, and the potential regional implications are discussed using maps of satellite and reanalyses products, including radiation and cloud cover.
NTAS 16 sixteenth setting of the NTAS Ocean Reference Station cruise on board RV Endeavor January 21 - February 8, 2017 Narragansett, Rhode Island - San Juan, Puerto Rico

(Woods Hole Oceanographic Institution, 2017-07) Bigorre, Sebastien P. ; Pietro, Benjamin ; Hasbrouck, Emerson ; Bigorre, Sébastien

The Northwest Tropical Atlantic Station (NTAS) was established to address the need for accurate air-sea flux estimates and upper ocean measurements in a region with strong sea surface temperature anomalies and the likelihood of significant local air–sea interaction on inter-annual to decadal timescales. The approach is to maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 15N, 51W by successive mooring turnarounds. These observations are used to investigate air–sea interaction processes related to climate variability. The NTAS Ocean Reference Station (ORS NTAS) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Ocean Observing and Monitoring Division. This report documents recovery of the NTAS-15 mooring and deployment of the NTAS-16 mooring. Both moorings used Surlyn foam buoys as the surface element. These buoys were outfitted with two Air–Sea Interaction Meteorology (ASIMET) systems. Each system measures, records, and transmits via Argos satellite the surface meteorological variables necessary to compute air–sea fluxes of heat, moisture and momentum. The upper 160 m of the mooring line were outfitted with oceanographic sensors for the measurement of temperature, salinity and velocity. The mooring turnaround was done by the Upper Ocean Processes Group of the Woods Hole Oceanographic Institution (WHOI), onboard R/V Endeavor (cruise EN590). The cruise took place between January 21 and February 8 2017. The NTAS-16 mooring was deployed on January 30, and the NTAS-15 mooring was recovered on January 31. A 24-hour intercomparison period was conducted on January 29 in front of the NTAS 15 buoy, and again on February 1 in front of the NTAS 16 buoy. During the inter-comparisons, data from instrumentation on the buoys, telemetered through Argos satellite system, and the ship’s meteorological and oceanographic measurements were monitored while the ship was stationed 0.2 nm downwind of the buoys. This report describes these operations, as well as other work done on the cruise and some of the pre-cruise buoy preparations. Other operations during EN590 consisted in the recovery and deployment of the Meridional Overturning Variability Experiment (MOVE) Pressure Inverted Echo Sounders (PIES) at two MOVE arrays (MOVE 1 in the east, and MOVE 3 in the west near Guadeloupe). Acoustic downloads of data from (PIES) and subsurface mooring (MOVE1, 3 and 4) were also conducted. MOVE is designed to monitor the integrated deep meridional flow in the tropical North Atlantic.
Accuracy of wind observations from open-ocean buoys: correction for flow distortion

(American Meteorological Society, 2020-04-20) Schlundt, Michael ; Farrar, J. Thomas ; Bigorre, Sebastien P. ; Plueddemann, Albert J. ; Weller, Robert A.

The comparison of equivalent neutral winds obtained from (i) four WHOI buoys in the subtropics and (ii) scatterometer estimates at those locations reveals a root-mean-square (RMS) difference of 0.56–0.76 m s−1. To investigate this RMS difference, different buoy wind error sources were examined. These buoys are particularly well suited to examine two important sources of buoy wind errors because 1) redundant anemometers and a comparison with numerical flow simulations allow us to quantitatively assess flow distortion errors, and 2) 1-min sampling at the buoys allows us to examine the sensitivity of buoy temporal sampling/averaging in the buoy–scatterometer comparisons. The interanemometer difference varies as a function of wind direction relative to the buoy wind vane and is consistent with the effects of flow distortion expected based on numerical flow simulations. Comparison between the anemometers and scatterometer winds supports the interpretation that the interanemometer disagreement, which can be up to 5% of the wind speed, is due to flow distortion. These insights motivate an empirical correction to the individual anemometer records and subsequent comparison with scatterometer estimates show good agreement.
Stratus 12 : twelfth setting of the Stratus Ocean Reference Station

(Woods Hole Oceanographic Institution, 2012-10) Bigorre, Sebastien P. ; Weller, Robert A. ; Lord, Jeffrey ; Galbraith, Nancy R. ; Whelan, Sean P. ; Holte, James W. ; Cifuentes, Ursula ; Sanchez, Eric ; Labbe-Ibanez, Pamela A. ; Raboya, Magda Mindiola ; Oltman, Susan ; Denton, Elsie ; Shambaugh, James

The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide ongoing climate-quality records of surface meteorology, air-sea fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Climate Observation Program. It is recovered and redeployed annually. A NOAA vessel was not available, so this cruise was conducted on the Melville, operated by the Scripps Institution of Oceanography. During the 2012 cruise on the Melville to the ORS Stratus site, the primary activities were the deployment of the Stratus 12 WHOI surface mooring, recovery of the previous (Stratus 11) WHOI surface mooring, in-situ calibration of the buoy meteorological sensors by comparison with instrumentation installed on the ship, and collection of underway and on station oceanographic data to continue to characterize the upper ocean in the stratus region. Underway CTD (UCTD) profiles were collected along the track. Surface drifters and subsurface floats were also launched along the track.
Stratus 14 : fourteenth setting of the Stratus Ocean Reference Station cruise on board RV Cabo de Hornos April 14 - 30, 2015 Valparaiso, Chile

(Woods Hole Oceanographic Institution, 2015-04) Bigorre, Sebastien P. ; Weller, Robert A. ; Lord, Jeffrey ; Galbraith, Nancy R. ; Hasbrouck, Emerson ; Pezoa, Sergio ; Blomquist, Byron

The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide ongoing climate-quality records of surface meteorology, air-sea fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Climate Observation Program. It is recovered and redeployed annually, with past cruises that have come between October and January. This cruise was conducted on the Chilean research vessel Cabo de Hornos. During the 2015 cruise on the Cabo de Hornos to the ORS Stratus site, the primary activities were the recovery of the previous (Stratus 13) WHOI surface mooring, deployment of the new Stratus 14 WHOI surface mooring, in-situ calibration of the buoy meteorological sensors by comparison with instrumentation installed on the ship and CTD casts near the moorings. Surface drifters were also launched along the track.
Eddies and an extreme water mass anomaly observed in the eastern south Pacific at the Stratus mooring

(John Wiley & Sons, 2014-02-12) Stramma, Lothar ; Weller, Robert A. ; Czeschel, Rena ; Bigorre, Sebastien P.

In the tropical eastern South Pacific the Stratus Ocean Reference Station (ORS) (∼20°S, 85.5°W) is located in the transition zone between the oxygen minimum zone (OMZ) and the well-oxygenated subtropical gyre. In February/March 2012, extremely anomalous water mass properties were observed in the thermocline at the Stratus ORS. The available eddy oxygen anomaly was −10.5 × 1016 µmol. This anomalous water was contained in an anticyclonic mode-water eddy crossing the mooring site. This eddy was absorbed at that time by an anticyclonic feature located south of the Stratus mooring. This was the largest water property anomaly observed at the mooring during the 13.5 month deployment period. The sea surface height anomaly (SSHA) of the strong mode-water eddy in February/March 2012 was weak, and while the lowest and highest SSHA were related to weak eddies, SSHA is found not to be sufficient to specify the eddy strength for subsurface-intensified eddies. Still, the anticyclonic eddy, and its related water mass characteristics, could be tracked backward in time in SSHA satellite data to a formation region in April 2011 off the Chilean coast. The resulting mean westward propagation velocity was 5.5 cm s−1. This extremely long-lived eddy carried the water characteristics from the near-coastal Chilean water to the open ocean. The water mass stayed isolated during the 11 month travel time due to high rotational speed of about 20 cm s−1 leading to almost zero oxygen in the subsurface layer of the anticyclonic mode-water eddy with indications of high primary production just below the mixed layer.
Stratus 15 fifteenth setting of the Stratus Ocean Reference Station cruise on board RV Cabo de Hornos June 15 – 29, 2016 Valparaiso, Chile – Valparaiso, Chile

(Woods Hole Oceanographic Institution, 2016-10) Bigorre, Sebastien P. ; Weller, Robert A. ; Lord, Jeffrey ; Hasbrouck, Emerson ; Pietro, Benjamin ; Gazale, Dario Torres ; Jiménez, Ignacio Burgos

The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide ongoing climate-quality records of surface meteorology, air-sea fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National Oceanic and Atmospheric Administration’s (NOAA) Climate Observation Program. It is recovered and redeployed annually, with past cruises that have come between October and May. This cruise was conducted on the Chilean research vessel Cabo de Hornos. During the 2016 cruise on the Cabo de Hornos to the ORS Stratus site, the primary activities were the recovery of the previous (Stratus 14) WHOI surface mooring, deployment of the new Stratus 15 WHOI surface mooring, in-situ calibration of the buoy meteorological sensors by comparison with instrumentation installed on the ship, CTD casts near the moorings. Surface drifters and ARGO floats were also launched along the track.

Bigorre Sebastien P.

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