Search

Satellite sea level anomaly (SLA) and sea surface salinity (SSS) data are used to characterize and quantify the contribution of mesoscale eddies to the ocean transport of salt. Given relatively large errors in satellite SSS retrievals, we evaluate the eddy transport of salt using two methods. The first method is based on the so-called eddy composite analysis. Because of the averaging over a large number of eddies in a given geographic area, composite eddies result in quite small standard errors, producing robust estimates of the associated transport of salt. The second method estimates the eddy transport of salt in a traditional way by computing pointwise covariances between eddy-induced velocity and SSS fluctuations. Comparing between the two methods, we find that the estimates of the eddy salt transport agree very well globally, emphasizing the physical mechanism responsible for the eddy transport of salt (eddy advection) and validating the assumption that the eddy transport is mainly due to large mesoscale eddies, observed by satellite altimetry. Our analysis confirms that the eddy transport of salt (or, equivalently, freshwater) is an essential component of the marine hydrological cycle. The regions of major eddy transport of salt identified in our study occur in the tropical belt, across the equatorward limbs of the subtropical gyres, and across the Antarctic Circumpolar Current (ACC). The eddy salt transport is poleward across the ACC with the largest transport taking place in the Indian Ocean sector. The eddy salt transport is divergent in the subtropical gyres (eddies pump salt out of the gyres) and convergent in the tropics. The eddy salt transport in the sub-polar gyres is substantially smaller than the eddy salt transport in the tropics and subtropics. We also note that the zonal component of the eddy salt transport is quite significant, particularly over the western and eastern boundaries of the gyres and in the near-equatorial belt, where strong zonal gradients of SSS exist. Overall, our study demonstrates that the possibility to characterize and quantify the eddy transport of salt in the ocean surface layer can rely on the combined use of satellite observations of SLA and SSS.

Для одержання достовірних результатів вимірювання під час проведення оцінки відповідності продукції важливо забезпечити метрологічне підтвердження застосованого вимірювального обладнання. Оцінка метрологічного підтвердження вимірювального обладнання свідчить про його відповідність поставленому вимірювальному завданню. Для правильного виконання цього завдання необхідна відповідна методика вимірювань. Під час виконання вимірювань згідно із визначеною методикою важливо чітко виконувати ті вимоги, які ставлять до вимірювального обладнання, умов проведення, послідовності операцій вимірювання, до фахівців. Виконання цих вимог дає можливість одержати достовірний результат з необхідною точністю. Впровадження ISO/IEC 17025:2017 є важливим кроком для встановлення вимог до проведення вимірювань з урахуванням вимог багатьох міжнародних документів, які містять вимоги до обладнання та методик випробувань (вимірювань). Ця редакція стандарту пропонує нормувати та оцінювати точність результату вимірювань не тільки за невизначеністю вимірювань, а й за іншими показниками точності. Проаналізовано міжнародні вимоги до обладнання, зокрема до вимірювального, методик випробувань (вимірювань) та нормування цих вимог обговорюваного стандарту. Важливим фактором впровадження стандарту в Україні є те, що все ще немає національних стандартів, які б регламентували загальні вимоги до використання засобів вимірювальної техніки та оцінювання точності результатів вимірювання. У стандарті, що розглядається, якраз викладено загальні підходи до використання обладнання та характеристик точності результатів, одержаних за відповідними методиками. It is important to carry out metrological confirmation of the used measuring equipment in order to obtain reliable measurement results during the conformity assessment of products. Assessment of the metrological confirmation of the measuring equipment confirms its conformity with the given measuring task. For proper performance of this task it is necessary to have an appropriate measurement technique. When performing measurements in accordance with a specified method, it is important to clearly comply with the requirements contained in the measuring equipment, the conditions of conducting, the sequence of measurement operations, and the requirements for specialists. The fulfillment of these requirements makes it possible to obtain a reliable result with the necessary accuracy. The implementation of ISO/IEC 17025:2017 is an important step in setting requirements for measurements. This edition of the standard proposes to standardize and evaluate the accuracy of the measurement result not only in uncertainty of measurements, but also in other indicators of accuracy. The analysis of international requirements for equipment, including measurement, techniques of test and measurement, and standardization of requirements of the discussed standard have been carried out. An important factor in the implementation of the standard in Ukraine is the absence of the national standards which could regulate the general requirements for measuring equipment application and assess the obtained results accuracy. In the standard under consideration, the general approaches to the use of equipment and to accuracy of the received results obtained by appropriate techniques are provided.

A method is presented for mapping sea surface salinity (SSS) from Aquarius level-2 along-track data in order to improve the utility of the SSS fields at short length [O(150 km)] and time [O(1 week)] scales. The method is based on optimal interpolation (OI) and derives an SSS estimate at a grid point as a weighted sum of nearby satellite observations. The weights are optimized to minimize the estimation error variance. As an initial demonstration, the method is applied to Aquarius data in the North Atlantic. The key element of the method is that it takes into account the so-called long-wavelength errors (by analogy with altimeter applications), referred to here as interbeam and ascending/descending biases, which appear to correlate over long distances along the satellite tracks. The developed technique also includes filtering of along-track SSS data prior to OI and the use of realistic correlation scales of mesoscale SSS anomalies. All these features are shown to result in more accurate SSS maps, free from spurious structures. A trial SSS analysis is produced in the North Atlantic on a uniform grid with 0.25° resolution and a temporal resolution of one week, encompassing the period from September 2011 through August 2013. A brief statistical description, based on the comparison between SSS maps and concurrent in situ data, is used to demonstrate the utility of the OI analysis and the potential of Aquarius SSS products to document salinity structure at ~150-km length and weekly time scales.

International Association of Physical Sciences of Oceans, Montreal, Canada, 20-24 July 2009

IEEE International Geoscience & Remote Sensing Symposium, DVD-ROM, 4 pages Available data for ocean temperature, salinity, and current at the present time do not have sufficient resolution to describe the variability in Atlantic Meridional Overturning Circulation (AMOC). To fill the gap, we are working on near real-time 3D synoptic temperature, salinity, and velocity (STSV) datasets from remotely sensed Argo profiling and trajectory data together with the Global Temperature-Salinity Profile Program (GTSPP), Navy’s MOODS, and the OSCAR data using the optimal spectral decomposition (OSD) method. With establishment of the STSV dataset, the AMOC variability can be effectively detected and predicted.

Acta Oceanlogica Sinica, Chinese Society of Oceanography Analysis of Argo float trajectories at 1000 m and temperature at 950 m in the North Atlantic between November 2003 and January 2005 demonstrates the existence of two different circulation modes with fast transition between them. Each mode has a pair of cyclonic anticyclonic gyres. The difference is the location of the cyclonic gyre. The cyclonic gyre stretches from southeast to northwest in the first mode and from the southwest to the northeast in the second monde. The observed modes strongly affect the heat and salt transport in the North Atlantic. In particular, the second mode slows down the westward transport of the warm and saline water from the Mediterranean Sea.

Journal of Physical Oceanography, American Meteorological Society, 35, 902-910. Fall–winter recurrence of current reversal from westward to eastward is identified on the Texas– Louisiana continental shelf using the current-meter [Texas–Louisiana Shelf Physical Oceanography Program (LATEX-A)] and near-surface drifting buoy [Surface Current and Lagrangian Drift Program (SCULP-1)] observations in 1993 and 1994. Reversal events roughly satisfy the Poisson distribution with one current reversal nearly every 12 days. Synoptic winds seem responsible for the current reversal events. Other processes such as offshore eddies shed from the Loop Current and river runoff are less important to change alongshore flow direction at synoptic scales. A statistical model is established to predict the synoptic current reversal using the surface wind observations.

Part 1 A new approach is developed to reconstruct a three-dimensional incompressible flow from noisy data in an open domain using a two-scalar (toroidal and poloidal) spectral representation. The results are presented in two parts: theory (first part) and application (second part). In Part I, this approach includes (a) a boundary extension method to determine normal and tangential velocities at an open boundary, (b) establishment of homogeneous open boundary conditions for the two potentials with a spatially varying coefficient k, (c) spectral expansion of k, (d) calculation of basis functions for each of the scalar potentials, and (e) determination of coefficients in the spectral decomposition of both velocity and k using linear or nonlinear regressions. The basis functions are the eigenfunctions of the Laplacian operator with homogeneous mixed boundary conditions and depend upon the spatially varying parameter k at the open boundary. A cost function used for poor data statistics is introduced to determine the optimal number of basis functions. An optimization scheme with iteration and regularization is proposed to obtain unique and stable solutions. In Part II, the capability of the method is demonstrated through reconstructing a 2D wind-driven circulation in a rotating channel, a baroclinic circulation in the eastern Black Sea, and a large-scale surface circulation in the Southern Ocean. This research was sponsored by the Office of Naval Research, Naval Oceanographic Office, and the Naval Postgraduate School. Leonid Ivanov, Tatyana Korzhova, Tatyana Margolina, and Oleg Melnichenko thank U.S. Civilian Research and Development Foundation for sup- port received through Award UG-2079.

Journal of the Atmospheric Sciences, American Meteorological Society, 59

Geophysical Research Letters, American Geophysical Union, 29 (15), 10.1029/2002GLO14891. The article of record as published may be located at http://dx.doi.org/10.1029/2002GL014891 Ocean predictability skill is investigated using a Gulf of Mexico nowcast/forecast model. Power law scaling is found in the mean square error of displacement between drifting buoy and model trajectories (both at 50 m depth). The probability density function of the model valid prediction period (VPP) is asymmetric with a long and broad tail on the higher value side, which suggests longterm predictability. The calculations demonstrate that the long-term (extreme long such as 50–60 day) predictability is not an "outlier" and shares the same statistical properties as the short-term predictions.

Joint Assembles of the International Association for Physical Sciences of the Oceans, International Association for Biological Oceanography, Mar del Plata, Argentina, 22-26 October 2001