Category: Scientific Papers (Abstract & PDF)

Argo Data 1999–2019: Two Million Temperature-Salinity Profiles and Subsurface Velocity Observations From a Global Array of Profiling Floats

Wong, A. P., Wijffels, S. E., Riser, S. C., Pouliquen, S., Hosoda, S., Roemmich, D., … & Park, H. (2020). Argo Data 1999–2019: Two Million Temperature-Salinity Profiles and Subsurface Velocity Observations From a Global Array of Profiling Floats. Front. Mar. Sci. 7:700. doi: 10.3389/fmars.2020.00700

Abstract: In the past two decades, the Argo Program has collected, processed, and distributed over two million vertical profiles of temperature and salinity from the upper two kilometers of the global ocean. A similar number of subsurface velocity observations near 1,000 dbar have also been collected. This paper recounts the history of the global Argo Program, from its aspiration arising out of the World Ocean Circulation Experiment, to the development and implementation of its instrumentation and telecommunication systems, and the various technical problems encountered….

Read Full Paper.

Read More

OSSE Assessment of Underwater Glider Arrays to Improve Ocean Model Initialization for Tropical Cyclone Prediction

Halliwell Jr, G. R., Goni, G. J., Mehari, M. F., Kourafalou, V. H., Baringer, M., & Atlas, R. (2020). OSSE Assessment of Underwater Glider Arrays to Improve Ocean Model Initialization for Tropical Cyclone Prediction. Journal of Atmospheric and Oceanic Technology, 37(3), 467-487.

Abstract: Credible tropical cyclone (TC) intensity prediction by coupled models requires accurate forecasts of enthalpy flux from ocean to atmosphere, which in turn requires accurate forecasts of sea surface temperature cooling beneath storms. Initial ocean fields must accurately represent ocean mesoscale features and the associated thermal and density structure. Observing system simulation experiments (OSSEs) are performed to quantitatively assess the impact of assimilating profiles collected from multiple underwater gliders deployed over the western North Atlantic Ocean TC region, emphasizing advantages gained by profiling from moving versus stationary platforms. Assimilating ocean profiles collected repeatedly at fixed locations produces large root-mean-square error reduction only within ~50 km of each profiler for two primary reasons…

Download full PDF.

Read More

Highly variable upper and abyssal overturning cells in the South Atlantic

Kersale, M., Meinen, C. S., Perez, R. C., Le Henaff, M., Valla, D., Lamont, T., … & Garzoli, S. L. (2020). Highly variable upper and abyssal overturning cells in the South Atlantic. Science advances, 6(32), eaba7573.

Abstract: The Meridional Overturning Circulation (MOC) is a primary mechanism driving oceanic heat redistribution on Earth, thereby affecting Earth’s climate and weather. However, the full-depth structure and variability of the MOC are still poorly understood, particularly in the South Atlantic. This study presents unique multiyear records of the oceanic volume transport of both the upper (<~3100 meters) and abyssal (>~3100 meters) overturning cells based on daily moored measurements in the South Atlantic at 34.5°S. The vertical structure of the time-mean flows is consistent with the limited historical observations. Both the upper and abyssal cells exhibit a high degree of variability relative to the temporal means at time scales, ranging from a few days to a few weeks. Observed variations in the abyssal flow appear to be largely independent of the flow in the overlying upper cell. No meaningful trends are detected in either cell.

Download full pdf.

Read More

Autonomy, Artificial Intelligence, and Telepresence: Advancing Ocean Science at Sea in the COVID-19 Era

Tim Gallaudet, Jamese Sims, Elizabeth Lobecker, Amanda Netburn, Charles Alexander,Kelly Goodwin, and Alexandra Skrivanek. Autonomy, Artificial Intelligence, and Telepresence: Advancing Ocean Science at Sea in the COVID-19 Era. Journal of Ocean Technology, 15(4) 2020

The COVID-19 pandemic has impacted all aspects of society, including seagoing marine science. Social distance measures and quarantine restrictions have required smaller scientific teams and crews on oceanographic ships. Advances in technology offer the potential to continue marine science discovery as the impacts of the pandemic persist. Robotics and uncrewed systems are already widely used in place of in-situ, human-operated systems, while autonomy and artificial intelligence are dramatically increasing the efficiency and effectiveness of nearly every ocean science discipline, including biological observations. Telepresence is a proven capability that can transform any vessel into a virtual international laboratory. We will describe how these tools are applied at the National Oceanic and Atmospheric Administration (NOAA), and how they provide capabilities to move ocean science forward over the course of the COVID-19 pandemic and beyond.

Read the Full Essay

Read More

Eye of the Storm: Observing Hurricanes with a Small Unmanned Aircraft System

Cione, J. J., Bryan, G. H., Dobosy, R., Zhang, J. A., de Boer, G., Aksoy, A., … & Chen, X. (2020). Eye of the storm: observing hurricanes with a small unmanned aircraft system. Bulletin of the American Meteorological Society, 101(2), E186-E205.

Abstract: Unique data from seven flights of the Coyote small unmanned aircraft system (sUAS) were collected in Hurricanes Maria (2017) and Michael (2018). Using NOAA’s P-3 reconnaissance aircraft as a deployment vehicle, the sUAS collected high-frequency (>1 Hz) measurements in the turbulent boundary layer of hurricane eyewalls, including measurements of wind speed, wind direction, pressure, temperature, moisture, and sea surface temperature, which are valuable for advancing knowledge of hurricane structure and the process of hurricane intensification. This study presents an overview of the sUAS system and preliminary analyses that were enabled by these unique data. Among the most notable results are measurements of turbulence kinetic energy and momentum flux for the first time at low levels (<150 m) in a hurricane eyewall. At higher altitudes and lower wind speeds, where data were collected from previous flights of the NOAA P-3...

Read Full Paper.

Read More

Inferring Florida Current Volume Transport From Satellite Altimetry

Volkov, D. L., Domingues, R., Meinen, C. S., Garcia, R., Baringer, M., Goni, G., & Smith, R. H. (2020). Inferring Florida Current volume transport from satellite altimetry. Journal of Geophysical Research: Oceans, e2020JC016763.

Plain Language Summary: Florida Current (FC) is one of the major conduits of heat, salt, carbon, nutrients and other properties in the subtropical North Atlantic, with profound influences on regional weather, climate, sea‐level, and ecosystems. Daily monitoring of the FC volume transport with a submarine cable has been maintained nearly continuously since 1982. Because of the extremely high value of these measurements for Earth system studies, efforts are underway to find a suitable backup observing system for the inevitable future when the cable fails. Satellites have been providing accurate measurements of sea level for nearly 3 decades. Due to the Earth’s rotation, the direction of major oceanic currents is parallel to the lines of constant sea level, which for the FC translates into sea level near the Bahamas being about 1‐m higher than sea level along Florida east coast. Variations in the FC…

Read Full Paper.

Read More

Interannual Variability of the South Atlantic Ocean Heat Content in a High‐Resolution Versus a Low‐Resolution General Circulation Model

Gronholz, A., Dong, S., Lopez, H., Lee, S. K., Goni, G., & Baringer, M. (2020). Interannual variability of the South Atlantic Ocean heat content in a high‐resolution versus a low‐resolution General Circulation Model. Geophysical Research Letters, e2020GL089908.

Plain Language Summary: In this study we analyze heat content changes of the upper South Atlantic Ocean and the impact of model resolution on these changes. Results from two numerical simulations are compared. One simulation with high‐resolution allows smaller‐scale processes directly, while the other simulation with low‐resolution does not. In both simulations oceanic heat transport dominates the ocean heat content changes on interannual time scale, while atmospheric fluxes play a secondary role. The heat anomalies, however, originate from different regions in the two simulations. While the oceanic heat transport from the south dominates in the high‐resolution simulation, oceanic heat transport from the north dominates in the low‐resolution simulation. Furthermore, wind‐induced surface heat transport plays a significant role in the low‐resolution while the heat transport in the high‐resolution simulation is dominated by…

Read Full Paper.

Read More

Subsurface Automated Samplers (SAS) for Ocean Acidification Research

ENOCHS, I.C., N. FORMEL, L. SHEA, L. CHOMIAK, A. Piggot, A. KIRKLAND, and D. MANZELLO. Subsurface automated samplers (SAS) for ocean acidification research. Bulletin of Marine Science, 96(4):735-752 (https://doi.org/10.5343/bms.2020.0018) (2020).

Abstract: Ocean acidification (OA) is the process whereby anthropogenic carbon dioxide is absorbed into seawater, resulting in altered carbonate chemistry and a decline in pH. OA will negatively impact numerous marine organisms, altering the structure and function of entire ecosystems. The progression of OA, while faster than has occurred in recent geological history, has been subtle and detection may be complicated by high variability in shallow-water environments. Nevertheless, comprehensive monitoring and characterization is important given the scale and severity of the problem. Presently, technologies used to measure OA in the field are costly and limited by their detection of only one carbonate chemistry parameter, such as pH. Discrete water samples, by contrast, offer a means of measuring multiple components of the carbonate system, including parameters of particular explanatory value (e.g., total alkalinity, dissolved inorganic carbon), for which field-based sensors do not presently exist…

Read Full Article

Read More

Madden–Julian Oscillation–Induced Suppression of Northeast Pacific Convection Increases U.S. Tornadogenesis

Kim, D., Lee, S. K., & Lopez, H. (2020). Madden–Julian Oscillation–Induced Suppression of Northeast Pacific Convection Increases US Tornadogenesis. Journal of Climate, 33(11), 4927-4939.

This study investigates the impact of the Madden–Julian oscillation (MJO) on U.S. tornadogenesis using atmospheric reanalysis and model experiments. Our analysis shows that the impact of MJO on U.S. tornadogenesis is most significant in May–July and during MJO phases 3–4 and 5–6 (P3456). These MJO phases are characterized by anomalous ascending motion over the Maritime Continent (MC) and anomalous subsidence over the northeast Pacific (EP), generating anomalous diabatic heating and cooling, respectively. These in turn generate large-scale atmospheric conditions conducive to tornadogenesis in the United States, enhancing the North American low-level jet (NALLJ) and thus increasing the influx of warm and moist air from the Gulf of Mexico to the United States and increasing the low-level wind shear and convective available potential energy along its path…

Read Full Paper

Read More

Observed Ocean Bottom Temperature Variability at Four Sites in the Northwestern Argentine Basin: Evidence of Decadal Deep/Abyssal Warming Amidst Hourly to Interannual Variability During 2009–2019

Meinen, C. S., Perez, R. C., Dong, S., Piola, A. R., & Campos, E. (2020). Observed ocean bottom temperature variability at four sites in the northwestern Argentine Basin: Evidence of decadal deep/abyssal warming amidst hourly to interannual variability during 2009‐2019. Geophysical Research Letters, e2020GL089093.

Consecutive multiyear records of hourly ocean bottom temperature measurements are merged to produce new decade‐long time series at four depths ranging from 1,360 to 4,757 m within the northwest Argentine Basin at 34.5°S. Energetic temperature variations are found at a wide range of time scales. All sites exhibit fairly linear warming trends of approximately 0.02–0.04°C per decade over the period 2009–2019, although the trends are only statistically different from zero at the two deepest sites at depths of ~4,500–4,800 m. Near‐bottom temperatures from independent conductivity‐temperature‐depth profiles collected at these same locations every 6–24 months over the same decade…

Read full paper

Read More