Janet J. Fredericks

Measurements of Momentum and Heat Transfer across the Air–Sea Interface

Abstract This study makes direct measurements of turbulent fluxes in the mixed layer in order to close heat and momentum budgets across the air–sea interface and to assess the ability of rigid-boundary turbulence models to predict mean vertical gradients beneath the ocean’s wavy surface. Observations were made at 20 Hz at nominal depths of 2.2 and 1.7 m in ∼16 m of water. A new method is developed to estimate the fluxes and the length scales of dominant flux-carrying eddies from cospectra at frequencies below the wave band. The results are compared to independent estimates of those quantities, with good agreement between the two sets of estimates. The observed temperature gradients were smaller than predicted by standard rigid-boundary closure models, consistent with the suggestion that wave breaking and Langmuir circulation increase turbulent diffusivity in the upper ocean. Similarly, the Monin–Obukhov stability function ϕh was smaller in the authors’ measurements than the stability functions used in rig...

Stress, Salt Flux, and Dynamics of a Partially Mixed Estuary

Funding was provided by the National Science Foundation under Grant OCE-94-15617 and The Hudson River Foundation.

Observations of near-bottom flow in a wave-dominated nearshore environment

Funding was provided by the Coastal Sciences Program of the Office of Naval Research under Grant N00014-92-J-12300.

A summary of quality control tests for waves and in situ currents and their effectiveness

This paper summarizes the quality control (QC) tests used to verify ocean wave and in situ current data collected and shared by ocean observing systems, federal data centers and oceanographic research institutions. The categories in common for both waves and currents are defined as: (1) sensor health, (2) signal quality, and (3) parameter quality. The main differences being that while wave measurements require an additional category of spectral quality tests, the in situ current measurements from ADCPs require overall profile quality tests. Implementing QC tests and measuring their effectiveness has identified the need for multi-parameter quality control algorithms. While the threshold of a given parameter can vary due to the environment, it can be tuned. The Quality Assurance of Real-Time Ocean Data (QARTOD) workshops and subsequent work has directly led to the results presented in this paper.

Turbulence in the shallow nearshore environment during SANDYDUCK '97

Funding was provided by the National Science Foundation under Grant No. OCE-9810609, the Mellon Foundation and Rinehart Coastal Research Center.

Fluid Mechanical Measurements within the Bottom Boundary Layer During Coastal Mixing and Optics

Funding was provided by the Office of Naval Research under contract number N00014-95-1-0373.

Promoting the capture of sensor data provenance: a role-based approach to enable data quality assessment, sensor management and interoperability

Sensor technologies and capabilities have an effect on observational data quality. Typically, data management begins, at best, when a data manager obtains the data and needs to describe it sufficiently to data consumers. Often, the sensing methods are not adequately described and the data manager does not know the appropriate questions to ask or where to direct questions about sensors, their configuration, and the deployment. Consequently, knowledge often remains buried in sensor manuals and field operator logs. Thus, most metadata requirements have been simplified to accommodate this gap in knowledge.When information is captured where it is best understood and tools are created to easily capture this knowledge, machine-actionable descriptions can be provided to adequately describe the processes taken in generating observations. The information can be associated with the data and thus be accessible, discoverable and used in data quality control by data providers and in data quality assessment by the data consumers.Here, we define actors and actions to promote role-based creation of fully-described, standards-based documents. These documents can be created in SensorML (OGC SWE) that includes links to resolvable term definitions (W3C Semantic Web), enabling the creation of associated mappings and ontologies to extend and resolve the meaning of each term.

Enabling quality assessment through web services

Emerging technologies in web-based services have enabled the integration of global, interdisciplinary earth observations. These capabilities can provide an unprecedented opportunity to promote the establishment and adoption of standards for the delivery of information about sensor systems which can enable data quality assessment by disparate users. Machine-to-machine harvesting of data can either become a barrier to content (i.e., easy to get data but hard to determine lineage and provenance) or it can promote communication of critical metadata (i.e., easy to get data with fully described sensor and processing systems). In this contribution, we describe how Open-Geospatial Consortium (OGC) frameworks can enable web services with fully-described sensor systems, including processing lineage. Also presented here is an OGC Sensor Web Enablement (SWE) demonstration project describing the processing and sensor system used to measure real-time in situ currents and wave parameters.

Vorticity Measurements within the Bottom Boundary Layer in the Strait of Juan De Fuca

Abstract : Electromagnetic fluctuations and turbulent vorticity fluctuations were measured over a nine month period in the strong tidal flows of the Strait of Juan De Fuca off the coast of the Olympic Peninsula of Washington. A collaborative experiment was designed to test the hypothesis that electromagnetic fluctuations at the sea floor are forced by turbulent vorticity fluctuations in the bottom boundary layer. This report describes the measurement of turbulent vorticity fluctuations and the associated analysis which focuses on testing existing theoretical predictions for the inertial subrange and on characterizing spectra at frequencies below the inertial subrange.