Saildrone: adaptively sampling the marine environment

Author Posting. © American Meteorological Society, 2020. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 101(6), (2020): E744-E762, doi:10.1175/BAMS-D-19-0015.1.From 11 April to 11 June 2018 a new type of ocean observing platform, the Saildrone surface vehicle, collected data on a round-trip, 60-day cruise from San Francisco Bay, down the U.S. and Mexican coast to Guadalupe Island. The cruise track was selected to optimize the science team’s validation and science objectives. The validation objectives include establishing the accuracy of these new measurements. The scientific objectives include validation of satellite-derived fluxes, sea surface temperatures, and wind vectors and studies of upwelling dynamics, river plumes, air–sea interactions including frontal regions, and diurnal warming regions. On this deployment, the Saildrone carried 16 atmospheric and oceanographic sensors. Future planned cruises (with open data policies) are focused on improving our understanding of air–sea fluxes in the Arctic Ocean and around North Brazil Current rings.The Saildrone data collection mission was sponsored by the Saildrone Award, an annual data collection mission awarded by Saildrone Inc., and the Schmidt Family Foundation. The research was funded by the NASA Physical Oceanography Program Grant 80NSSC18K0837 and 80NSSC18K1441. The work by T. M. Chin, J. Vazquez-Cuerzo, and V. Tsontos was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Piero L.F. Mazzini was supported by California Sea Grant Award NA18OAR4170073. We thank CeNCOOS for providing the HF radar data in the Gulf of the Farallones. Jose Gomez-Valdes was supported by CONACYT Grant 257125, and by CICESE. Work by Joel Scott and Ivona Cetinic was supported through NASA PACE. The work by Lisan Yu was supported by NOAA Ocean Observing and Monitoring Division under Grant NA14OAR4320158

Half a century of satellite remote sensing of sea-surface temperature

Sea-surface temperature (SST) was one of the first ocean variables to be studied from earth observation satellites. Pioneering images from infrared scanning radiometers revealed the complexity of the surface temperature fields, but these were derived from radiance measurements at orbital heights and included the effects of the intervening atmosphere. Corrections for the effects of the atmosphere to make quantitative estimates of the SST became possible when radiometers with multiple infrared channels were deployed in 1979. At the same time, imaging microwave radiometers with SST capabilities were also flown. Since then, SST has been derived from infrared and microwave radiometers on polar orbiting satellites and from infrared radiometers on geostationary spacecraft. As the performances of satellite radiometers and SST retrieval algorithms improved, accurate, global, high resolution, frequently sampled SST fields became fundamental to many research and operational activities. Here we provide an overview of the physics of the derivation of SST and the history of the development of satellite instruments over half a century. As demonstrated accuracies increased, they stimulated scientific research into the oceans, the coupled ocean-atmosphere system and the climate. We provide brief overviews of the development of some applications, including the feasibility of generating Climate Data Records. We summarize the important role of the Group for High Resolution SST (GHRSST) in providing a forum for scientists and operational practitioners to discuss problems and results, and to help coordinate activities world-wide, including alignment of data formatting and protocols and research. The challenges of burgeoning data volumes, data distribution and analysis have benefited from simultaneous progress in computing power, high capacity storage, and communications over the Internet, so we summarize the development and current capabilities of data archives. We conclude with an outlook of developments anticipated in the next decade or so

Ecoregional Analysis of Nearshore Sea-Surface Temperature in the North Pacific

The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. To better understand present temperature regimes, we assembled a 29-year nearshore time series of mean monthly SSTs along the North Pacific coastline using remotely-sensed satellite data collected with the Advanced Very High Resolution Radiometer (AVHRR) instrument. We then used the dataset to describe nearshore (<20 km offshore) SST patterns of 16 North Pacific ecoregions delineated by the Marine Ecoregions of the World (MEOW) hierarchical schema. Annual mean temperature varied from 3.8°C along the Kamchatka ecoregion to 24.8°C in the Cortezian ecoregion. There are smaller annual ranges and less variability in SST in the Northeast Pacific relative to the Northwest Pacific. Within the 16 ecoregions, 31–94% of the variance in SST is explained by the annual cycle, with the annual cycle explaining the least variation in the Northern California ecoregion and the most variation in the Yellow Sea ecoregion. Clustering on mean monthly SSTs of each ecoregion showed a clear break between the ecoregions within the Warm and Cold Temperate provinces of the MEOW schema, though several of the ecoregions contained within the provinces did not show a significant difference in mean seasonal temperature patterns. Comparison of these temperature patterns shared some similarities and differences with previous biogeographic classifications and the Large Marine Ecosystems (LMEs). Finally, we provide a web link to the processed data for use by other researchers

Sea surface temperature intercomparison in the framework of the Copernicus Climate Change Service (C3S)

A joint effort between the Copernicus Climate Change Service (C3S) and the Group for High Resolution Sea Surface Temperature (GHRSST) has been dedicated to an intercomparison study of eight global gap-free Sea Surface Temperature (SST) products to assess their accurate representation of the SST relevant to climate analysis. In general, all SST products show consistent spatial patterns and temporal variability during the overlapping time period (2003-2018). The main differences between each product are located in western boundary current and Antarctic Circumpolar Current regions. Linear trends display consistent SST spatial patterns among all products and exhibit a strong warming trend from 2012 to 2018 with the Pacific Ocean basin as the main contributor. SST discrepancy between all SST products is very small compared to the significant warming trend. Spatial power spectral density shows that the interpolation into 1o spatial resolution has negligible impacts on our results. The global mean SST time series reveals larger differences among all SST products during the early period of the satellite era (1982-2002) when there were fewer observations, indicating that the observation frequency is the main constraint of the SST climatology. The maturity matrix scores, which present the maturity of each product in terms of documentation, storage, and dissemination but not the scientific quality, demonstrate that ESA-CCI and OSTIA SST are well documented for users' convenience. Improvements could be made for MGDSST and BoM SST. Finally, we have recommended that these SST products can be used for fundamental climate applications and climate studies (e.g. El Nino)

Sinking Jelly-Carbon Unveils Potential Environmental Variability along a Continental Margin

Particulate matter export fuels benthic ecosystems in continental margins and the deep sea, removing carbon from the upper ocean. Gelatinous zooplankton biomass provides a fast carbon vector that has been poorly studied. Observational data of a large-scale benthic trawling survey from 1994 to 2005 provided a unique opportunity to quantify jelly-carbon along an entire continental margin in the Mediterranean Sea and to assess potential links with biological and physical variables. Biomass depositions were sampled in shelves, slopes and canyons with peaks above 1000 carcasses per trawl, translating to standing stock values between 0.3 and 1.4 mg C m2 after trawling and integrating between 30,000 and 175,000 m2 of seabed. The benthopelagic jelly-carbon spatial distribution from the shelf to the canyons may be explained by atmospheric forcing related with NAO events and dense shelf water cascading, which are both known from the open Mediterranean. Over the decadal scale, we show that the jelly-carbon depositions temporal variability paralleled hydroclimate modifications, and that the enhanced jelly-carbon deposits are connected to a temperature-driven system where chlorophyll plays a minor role. Our results highlight the importance of gelatinous groups as indicators of large-scale ecosystem change, where jelly-carbon depositions play an important role in carbon and energy transport to benthic systems

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

An analysis of SST gradients off the Peruvian coast : the impact of going to higher resolution

The Peruvian Coastal Upwelling System (PCUS) is one of the most productive fisheries in the world. Upwelling events are associated with changes in the magnitude and location of frontal structures. SST gradients from four different data sets, NCDC, REMSS, OSTIA, and MUR are compared in two test areas off the PCUS: Paita (5 degrees S) and Pisco (14 degrees S). In both areas gradients derived from the MUR data set show greater magnitudes, as well as larger seasonal cycles. Off Pisco, the magnitude of the seasonal cycle of 2.2 degrees C/100 km in MUR is larger than the one derived from the lower resolution data sets. All data sets at Pisco exhibit a seasonal cycle that peaks in late Austral summer and early fall. Hovmoller diagrams calculated at 5.5 degrees S, 10.5 degrees S, and 14.5 degrees S show clearly defined offshore maxima in the cross-shore gradients for all the data sets. Upwelling scales determined by the distance to the first maxima vary depending on the data set used. At 5.5 degrees S upwelling scales vary from 10 km for MUR to 50 km for NCDC At 14.5 degrees S the scales vary from 20 km for MUR to 40 km for OSTIA. All four data sets show similar large-scale structures associated with the Peruvian upwelling. However, MUR shows finer scale structures that are most likely due to submesoscale to mesoscale eddies. Sub-sampled MUR 1 km data at the 25 km, 9 km, and 4 km resolutions compare well in magnitude and phase with the lower resolution products. Agreement in gradient magnitude between the lower resolution data sets and the MUR sub-sampled at their respective resolutions implies that the pixel-to-pixel analysis noise in MUR is at a similar level as the other data sets

Change in El Nino flavours over 1958-2008 : implications for the long-term trend of the upwelling off Peru

The tropical Pacific variability has experienced changes in its characteristics over the last decades. In particular, there is some evidence of an increased occurrence of El Nino events in the central Pacific (a.k.a. 'Central Pacific El Nino' (CP El Nino) or 'El Nino Modoki'), in contrast with the cold tongue or Eastern Pacific (EP) El Nino which develops in the eastern Pacific. Here we show that the different flavours of El Nino imply a contrasted Equatorial Kelvin Wave (EKW) characteristic and that their rectification on the mean upwelling condition off Peru through oceanic teleconnection is changed when the CP El Nino frequency of occurrence increases. The Simple Ocean Data Assimilation (SODA) reanalysis product is first used to document the seasonal evolution of the EKW during CP and EP El Nino. It is shown that the strong positive asymmetry of ENSO (El Nino Southern Oscillation) is mostly reflected into the EKW activity of the EP El Nino whereas during CP El Nino, the EKW is negatively skewed in the eastern Pacific. Along with slightly cooler conditions off Peru (shallow thermocline) during CP El Nino, this is favourable for the accumulation of cooler SST anomalies along the coast by the remotely forced coastal Kelvin wave. Such a process is observed in a high-resolution regional model of the Humboldt Current system using the SODA outputs as boundary conditions. In particular the model simulates a cooling trend of the SST off Peru although the wind stress forcing has no trend. The model is further used to document the vertical structure along the coast during the two types of El Nino. It is suggested that the increased occurrence of the CP El Nino may also lead to a reduction of mesoscale activity off Peru

Change in El Niño flavours over 1958-2008: Implications for the long-term trend of the upwelling off Peru

International audienceThe tropical Pacific variability has experienced changes in its characteristics over the last decades. In particular, there is some evidence of an increased occurrence of El Niño events in the central Pacific (a.k.a. 'Central Pacific El Niño' (CP El Niño) or 'El Niño Modoki'), in contrast with the cold tongue or Eastern Pacific (EP) El Niño which develops in the eastern Pacific. Here we show that the different flavours of El Niño imply a contrasted Equatorial Kelvin Wave (EKW) characteristic and that their rectification on the mean upwelling condition off Peru through oceanic teleconnection is changed when the CP El Niño frequency of occurrence increases. The Simple Ocean Data Assimilation (SODA) reanalysis product is first used to document the seasonal evolution of the EKW during CP and EP El Niño. It is shown that the strong positive asymmetry of ENSO (El Niño Southern Oscillation) is mostly reflected into the EKW activity of the EP El Niño whereas during CP El Niño, the EKW is negatively skewed in the eastern Pacific. Along with slightly cooler conditions off Peru (shallow thermocline) during CP El Niño, this is favourable for the accumulation of cooler SST anomalies along the coast by the remotely forced coastal Kelvin wave. Such a process is observed in a high-resolution regional model of the Humboldt Current system using the SODA outputs as boundary conditions. In particular the model simulates a cooling trend of the SST off Peru although the wind stress forcing has no trend. The model is further used to document the vertical structure along the coast during the two types of El Niño. It is suggested that the increased occurrence of the CP El Niño may also lead to a reduction of mesoscale activity off Peru

2022 Arctic Saildrone Cruise Report

Saildrone is a wind and solar powered unmanned surface vehicle (USV) capable of long distance deployments lasting up to 12 months and providing high quality, near real-time, multivariate surface ocean and atmospheric observations while transiting at typical speeds of 3-5 knots. The drone is autonomous in that it may be guided remotely from land while being completely wind driven. The 2022 Saildrone Arctic campaign deployed two Saildrone unmanned surface vehicles (USV) during a 60-day cruise in the Bering and Chukchi Sea, from 18 June 2022 to 17 August 2022. The overall mission objective for 2022 was to measure atmospheric and oceanographic conditions in Alaskan arctic waters, specifically in collaboration with the Distributed Biological Observatory (DBO). The Saildrones transited to the Bering Strait, separating after reaching Point Hope, AK. SD-1041 then made repeat transects from Point Hope southwestward to near the International Date Line and back again, along DBO line #3. SD-1046 continued north to DBO line #4, and then when the sea ice retreated enough to allow safe passage, north again to DBO line #5. Each Saildrone was equipped to measure air temperature and relative humidity, barometric pressure, surface skin temperature, wind speed and direction, wave height and period, seawater temperature and salinity, chlorophyll fluorescence, and dissolved oxygen. Both vehicles measured near surface currents with 300 kHz acoustic Doppler current profilers (ADCP). Additionally, seven temperature data loggers were positioned vertically along the hull to provide further information on thermal variability near the ocean surface. This Saildrone Arctic dataset consists of 3 data files for each of the two NASA-funded Saildrones deployed, all in netCDF format and CF/ACDD compliant. One file contains saildrone platform telemetry and surface observational data (air temperature, sea surface skin and bulk temperatures, salinity, oxygen and chlorophyll-a concentrations, barometric pressure, wind speed and direction) at 1 minute temporal resolution. The second file contains the ADCP current vector data, depth-resolved to 100m at 2m intervals and binned temporally at 5 minute resolution. The third file contains the temperature logger measurement at different depths at 1 minute resolution. The project, Multi-sensor Improved Sea-Surface Temperature (MISST), is funded by NASA through the National Ocean Partnership Program (NOPP)