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Although the role of local wind forcing in modifying circulation in estuaries has received much attention over the past 15 years, the importance of non-local meteorological forcing has only recently been recognized. Studies in Chesapeake Bay (Elliott, 1978; Wang and Elliott, 1978; and Wang, 1978), Josenfjord (Svendsen, 1977), the Strait of Juan de Fuca (Holbrook and Halpern, 1977; Laird, Cannon, and Holbrook, 1978; and Holbrook and Halpern, 1979) and Resurrection Bay (Muench and Higgle, 1978) have shown that coastal winds can be highly coherent with axial estuary currents and that coastal Ekman dynamics may play a key role in generating up-estuary near-surface current reversals. This report discusses observations which illustrate the effects of seasonal variability in the local and nonlocal wind field on low-frequency estuarine circulation in the Strait of Juan de Fuca.

The two and three-dimensional response of strong ocean currents to atmospheric forcing is studied using numerical simulations. In particular, surface cooling is explored as a possible mechanism for explaining an observed 100 km southward shift in the mean position of the Gulf Stream during winter. The magnitude and direction of the cross-stream circulation is highly dependent on whether or not a vertical mixing of momentum occurs when the water column convectively adjusts in response to the surface cooling. A weak cross-stream flow toward the higher sea-surface temperatures occurs in the surface layer if momentum mixing does not occur, whereas a stronger flow toward lower sea-surface temperatures results if momentum mixing does take place. The response of three-dimensional simulations is very similar to the two-dimensional simulations in the immediate vicinity of the front. The response due to horizontal cooling gradients is not large enough to displace the Gulf Stream appreciably southward in any of the numerical simulations. By contrast, a moderate increase in the zonal wind stress is more effective in displacing the core of the current system than are strong gradients in the surface cooling. The position of the Gulf Stream has also been observed to change as it encounters changes in the bottom topography. The simulated adjustment of flow to a 200 m seamount is consistent with the conservation of potential vorticity. The inclusion of surface forcing does not affect the adjustment to the topography in any of the simulations, and does not steer the flow toward (away from) the topography so that the characteristics of the downstream flow are changed. http://archive.org/details/numericalsimulat1094521470 Approved for public release; distribution is unlimited.

The role of strong atmospheric forcing events in determining the evolution of the upper ocean during the fall and early winter cooling season was investigated. The historical series of surface and near-surface marine observations at three mid-latitude ocean weather ships (PAPA (OWS P), NOVEMBER (OWS N), and VICTOR (OWS V)) support the hypothesis that the integrated effects of these events dominate this evolution. For example, periods when the mechanical forcing was greater than the long-term mean accounted for approximately 35% of the time in the record examined at the three stations. However 85%/68%/57% of the sea-surface temperature change at OWS N/OWS P/OWS V occurred during these periods. Forty-nine data sets were examined and modeled during periods of intense fall and winter forcing. The significant thermal structure modifications observed during these strong events were simulated successfully using three modifications of the Kraus and Turner (1967) one-dimensional model. Evidence is presented which demonstrates that the amount of mechanically-generated turbulent kinetic energy available for entrainment decreases as the mixed-layer depth increases. Furthermore, in agreement with Gill and Turner (1976), these case studies suggest that only a small percentage of the convectively-generated turbulent kinetic energy is available for increasing the potential energy of the ocean by entrainment. (Author)

The rapid cooling of the mixed layer in the Arabian Sea during the southwest monsoon onset is examined. The atmospheric forcing fields over the Arabian Sea during the onsets in 1979, 1984, and 1985 are analyzed. Realistic wind speed and evaporative heat flux increases occur soon after onset. The solar radiation flux analyses suggest that both the Navy Operational Global Atmospheric Prediction System and the National Aeronautics and Space Administration four-dimensional data assimilation are too simplistic for accurate solar radiation flux calculations in the tropics. The solar radiation fluxes appear to be too low during the pre-onset periods and too high during the post-onset periods. The atmospheric forcing fields are then applied to a one-dimensional, ocean mixed layer model at four locations. The magnitude of the predicted sea-surface temperature decrease is 0.5 to 1.0°C during the 1984 and 1985 monsoon onsets. The results suggest that local atmospheric forcing accounts for most of the mixed layer cooling on a time scale of less than ten days and away from any major ocean current regions. The direct heat loss to the atmosphere contributes more to cooling of the mixed layer than does entrainment mixing at the base of the layer. http://archive.org/details/contributionoftm1094521740 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

Publisher Summary This chapter discusses the residual circulation in the North Sea. Hydrodynamic models of the North Sea are primarily concerned with tides, storm surges, and the associated currents, which can have velocities as high as several meters per second. However, the period of the dominant tide is only about a half day and the characteristic lifetime of a synoptic weather pattern is of the order of a few days. The very strong currents that are produced by the tides and the atmospheric forcing are thus relatively transitory and a marine biologist argues that, over time scales of biological interest, they change and reverse so many times that they more or less cancel out, leaving only a small residual contribution to the net water circulation. The role of residual currents and residual structures in the dynamics of marine populations, the long-term transport of sediments or the ultimate disposal of pollutants is universally recognized. A detailed study of the tidal residuals in the North Sea was made by the means of two coupled three-dimensional models, one for tides and storm surges, and one for the residual circulation.

Results are presented from preliminary experiments with an ocean general circulation model of the equatorial Pacific Ocean. The model has been developed to be suitable for investigating the response of the equatorial Pacific Ocean to seasonal and interannual variations in atmospheric forcing. A comparison is made of the model responses during the first eighty days of integration forced by: (1) a purely zonal idealised wind-stress distribution; and (2) the annual-mean wind-stress field. This study shows the ability of the real wind field to excite equatorial waves from within the basin interior and the role of the horizontal advection in redistributing temperature. Significant differences between the frictionally dominated surface circulations in the two experiments are attributed to features of the real wind-stress distribution and in particular the existence of cross-equatorial components.

A brief review of the characteristics of oceanic general circulation models (OGCMs) is presented, followed by a discussion of some aspects of the response of particular OGCMs to climatological and to variable atmospheric forcing. Furthermore the possibility of multiple steady states for the oceanic circulation is addressed.

Observations in the Gulf of Guinea during the summer of 1974 provide new information about the onset of summer surface cooling in the eastern equatorial Atlantic. Dramatic variations observed in the hydrological structure of the upper layer during summer are described. The seasonal SST signal is interpreted in terms of an annual component superimposed on an almost permanent EI Nino-like phenomenon in the eastern equatorial Atlantic. This interpretation of the observations is supported by recent theoretical considerations which demonstrate the possibility of an eastern tropical Atlantic response to remote atmospheric forcing on a seasonal time scale. ..

All recent climatic projections for the next century suggest that we are heading towards a warmer climate than today (Intergovernmental Panel on Climate Change; Fifth Assessment Report), driven by increasing atmospheric burdens of anthropogenic greenhouse gases. In particular, the volume mixing ratio of methane, the second-most important anthropogenic greenhouse gas, has increased by a factor of ~2.5 from the beginning of the European Industrial Revolution. Due to their complex responses to climatic factors, understanding of the dynamics of future global methane emissions and sinks is crucial for the next generation of climate projections. Of relevance to this problem, the Earth likely experienced warmer average temperatures than today during the Last Interglacial (LIG) period (130-115kaBP). Interestingly, ice cores do not indicate a different methane mixing ratio from the Pre-Industrial Holocene (PIH), in other words the current interglacial period prior to anthropogenic influence. This is surprising as warmer temperatures might be expected to increase methane emissions. The present study aims to improve our understanding of the changes in the global methane budget through quantifying the relative importance of sources and sinks of methane during the last full glacial-interglacial cycle.A fairly limited number of studies have investigated this cycle at the millenium time scale with most of them examining the doubling in CH4 from the Last Glacial Maximum (LGM) to the PIH. Though it is still a matter of debate, a general consensus suggests a predominant role to the change in methane emissions from wetlands and only a limited change in the oxidising capacity of the atmosphere. In the present study we provide an estimate of the relative importance of sources and sinks during the LIG period, using a complex climate-chemistry model to quantify the sinks, and a methane emissions model included in a global land surface model, for the sources. We are not aware of any previous studies that have explicitly tackled sources and sinks of methane in the previous interglacial. Our results suggest that both emissions and sinks of methane were higher during the LIG period, relative to the PIH, resulting in similar atmospheric concentrations of methane. Our simulated change in methane lifetime is primarily driven by climate (i.e. air temperature and humidity). However, a significant part of the reduced methane lifetime is also attributable to the impact of changes in NOx emissions from lightning. An increase in biogenic emissions of non-methane volatile organic compounds during the LIG seems unlikely to have compensated for the impact of temperature and humidity. Surface methane emissions from wetlands were higher in northern latitudes due to an increase of summer temperature, whilst the change in the tropics is less certain. Simulated methane emissions are strongly sensitive to the atmospheric forcing, with most of this sensitivity related to changes in wetland extent. © 2015 Elsevier Ltd.

The interannual variability (1948-1994) of the cold intermediate layer (CIL), defined here as the layer with T < 3°C, was investigated for six subregions of the Gulf of St. Lawrence. We first calculated a mean annual cycle of CIL properties for the six subregions (the Estuary, the Northwest, Northeast, Central, and Southern Gulf, and Cabot Strait). The midsummer warming rates thus obtained were then used to construct time series of the CIL core temperature extrapolated to July 15, using all available data from May 1 to September 30 of each year. Our most important result is that the mid-summer CIL core temperature was below normal from 1986 to 1994, this cold period being most intense from 1990 to 1994. We correlated the time series of CIL core temperature with average winter air temperatures from several weather stations inside and outside the Gulf to try to distinguish between local and remote atmospheric forcing and obtained the highest correlations with weather stations from the west coast of Newfoundland.

Preliminary analyses on the use of drift measurements of a buoy in the study of shelf currents are presented. The equipment was moored at Santa Catarina Shelf in Southern Brazil. The drift was measured by means of a GPS which provided buoy's geographical coordinates on an hourly basis. The data was decomposed in meridional and zonal position components and along with wind and sea level data, covered a period of 203 days from late summer (March 21 ) to late spring (October 11 ) of 2002. Statistical comparison between mean sea level (msl) and the meridional buoy positioning displayed very high correlation (R =0.83) with a 3 h delay in relation to msl. The best correlation between meridional wind and buoy's drift was attained at 10 h time lag (R =0.63). Sea level analysis characterizes the tide as mixed, mainly semidiurnal. Diurnal and Semi-Diurnal bands accounted for 63.6% of energy spectra in comparison to 36.4% on the Meteorological-forcing band. Low frequency signal in Meteorological band were clearly dominant in the buoy's meridional series, accounting for 90% of energy spectra. The buoy mooring system seems to work as a very useful indicator of the sense of geostrophic currents over the shelf, which seems to respond to both regional as well remote wind forcing.

Aerosol activation into cloud droplets is an important process that governs aerosol indirect effects. The advanced treatment of aerosol activation by Fountoukis and Nenes (2005) and its recent updates, collectively called the FN series, have been incorporated into a newly developed regional coupled climate-air quality model based on the Weather Research and Forecasting model with the physics package of the Community Atmosphere Model version 5 (WRF-CAM5) to simulate aerosol-cloud interactions in both resolved and convective clouds. The model is applied to East Asia for two full years of 2005 and 2010. A comprehensive model evaluation is performed for model predictions of meteorological, radiative, and cloud variables, chemical concentrations, and column mass abundances against satellite data and surface observations from air quality monitoring sites across East Asia. The model performs overall well for major meteorological variables including near-surface temperature, specific humidity, wind speed, precipitation, cloud fraction, precipitable water, downward shortwave and longwave radiation, and column mass abundances of CO, SO2, NO2, HCHO, and O3 in terms of both magnitudes and spatial distributions. Larger biases exist in the predictions of surface concentrations of CO and NOx at all sites and SO2, O3, PM2.5, and PM10 concentrations at some sites, aerosol optical depth, cloud condensation nuclei over ocean, cloud droplet number concentration (CDNC), cloud liquid and ice water path, and cloud optical thickness. Compared with the default Abdul-Razzack Ghan (2000) parameterization, simulations with the FN series produce ~107-113% higher CDNC, with half of the difference attributable to the higher aerosol activation fraction by the FN series and the remaining half due to feedbacks in subsequent cloud microphysical processes. With the higher CDNC, the FN series are more skillful in simulating cloud water path, cloud optical thickness, downward shortwave radiation, shortwave cloud forcing, and precipitation. The model evaluation identifies several areas of improvements including emissions and their vertical allocation as well as model formulations such as aerosol formation, cloud droplet nucleation, and ice nucleation. © 2015. American Geophysical Union. All Rights Reserved.

Seasonal cycle is the most significant signals of topography and circulation in the Bohai Sea (BS) and Yellow Sea (YS) forced by prevailing monsoon and is still poorly understood due to lack of data in their interiors. In the present study, seasonal cycles of topography in the BS and YS and its relationship with atmospheric forcing and oceanic adjustment were examined and discussed using TOPEX/Poseidon and ERS-1/2 Sea Level Anomalies (SLA) data. Analyses revealed complicated seasonal cycles of topography composed mainly of 2 REOF modes, the winter-summer mode (WIM) and spring-autumn mode (SAM). The WIM with action center in the BS displayed peak and southward pressure gradient in July, and valley and northward pressure gradient in January, which is obviously the direct response to monsoon with about 1-month response time. The SAM with action center in the western south YS displayed peak and northward pressure gradient in October and valley and southward pressure gradient in April. After the mature period of monsoon, the action center in the BS became weakened while that in the western south YS became strengthened because of regional convergence or divergence induced by seasonal variations of the Taiwan Warm Current and Yellow Sea Coastal Current. The direct response of topography to monsoon resulted in the WIM, while oceanic adjustment of topography played an important role in the forming of the SAM

The hydrology of the lake-rich Tibetan Plateau is important for the global climate, yet little is known about the thermal regime of Tibetan lakes due to scant data. We (i) investigated the characteristic seasonal temperature patterns and recent trends in the thermal and stratification regimes of lakes on the Tibetan Plateau and (ii) tested the performance of the one-dimensional lake parameterization scheme FLake for the Tibetan lake system. For this purpose, we combined 3 years of in situ lake temperature measurements, several decades of satellite observations, and the global reanalysis data. We chose the two largest freshwater Tibetan lakes, Ngoring and Gyaring, as study sites. The lake model FLake faithfully reproduced the specific features of the high-altitude lakes and was subsequently applied to reconstruct the vertically resolved heat transport in both lakes during the last 4 decades. The model suggested that Ngoring and Gyaring were ice-covered for about 6 months and stratified in summer for about 4 months per year with a short spring overturn and a longer autumn overturn. In summer the surface mixed boundary layer extended to 6–8 m of depth and was about 20 % shallower in the more turbid Gyaring. The thermal regime of the transparent Ngoring responded more strongly to atmospheric forcing than Gyaring, where the higher turbidity damped the response. According to the reanalysis data, air temperatures and humidity have increased, whereas solar radiation has decreased, since the 1970s. Surprisingly, the modeled mean lake temperatures did not change, nor did the phenology of the ice cover or stratification. Lake surface temperatures in summer increased only marginally. The reason is that the increase in air temperature was offset by the decrease in radiation, probably due to increasing humidity. This study demonstrates that air temperature trends are not directly coupled to lake temperatures and underscores the importance of shortwave radiation for the thermal regime of high-altitude lakes.

The Indian summer monsoon (ISM) is an important conveyor in the ocean–atmosphere coupled system on a trans-regional scale. Here we present a study of a sediment core from the northern Oman margin, revealing early to mid-Holocene ISM conditions on a near-20-year resolution. We assess multiple independent proxies indicative of sea surface temperatures (SSTs) during the upwelling season together with bottom-water conditions. We use geochemical parameters, transfer functions of planktic foraminiferal assemblages and Mg / Ca palaeothermometry, and find evidence corroborating previous studies showing that upwelling intensity varies significantly in coherence with solar sunspot cycles. The dominant ∼ 80–90-year Gleissberg cycle apparently also affected bottom-water oxygen conditions. Although the interval from 8.4 to 5.8 ka BP is relatively short, the gradually decreasing trend in summer monsoon conditions was interrupted by short events of intensified ISM conditions. Results from both independent SST proxies are linked to phases of weaker oxygen minimum zone (OMZ) conditions and enhanced carbonate preservation. This indicates that atmospheric forcing was intimately linked to bottom-water properties and state of the OMZ on decadal timescales.

Rapid coastal erosion threatens Arctic coastal infrastructure, including communities and industrial installations. Erosion of permafrost depends on numerous processes, including thermal and mechanical behaviour of frozen and unfrozen soil, nearshore hydrodynamics, atmospheric forcing, and the presence of sea ice. The quantification and numerical modelling of these processes is essential to predicting Arctic coastal erosion. This paper presents a case study of Baydaratskaya Bay, Russia, using the COSMOS numerical model to predict thermal-mechanical erosion. In particular, this study focuses on thermoabrasional rather than thermodenudational processes. A field dataset of onshore thermal and mechanical soil characteristics was supplemented by sources from the literature to serve as input for the model. A detailed sensitivity analysis has been conducted to determine the influence of key parameters on coastal erosion rates at the study site. This case study highlights the need for expanded data collection on Arctic coastlines and provides direction for future investigations.

Stochastic parameterization provides a methodology for representing model uncertainty in ensemble forecasts. Here the impact on forecast reliability over seasonal time scales of three existing stochastic parameterizations in the ocean component of a coupled model is studied. The relative impacts of these schemes upon the ocean mean state and ensemble spread are analyzed. The oceanic variability induced by the atmospheric forcing of the coupled system is, in most regions, the major source of ensemble spread. The largest impact on spread and bias came from the stochastically perturbed parameterization tendency (SPPT) scheme, which has proven particularly effective in the atmosphere. The key regions affected are eddy-active regions, namely, the western boundary currents and the Southern Ocean where ensemble spread is increased. However, unlike its impact in the atmosphere, SPPT in the ocean did not result in a significant decrease in forecast error on seasonal time scales. While there are good grounds for implementing stochastic schemes in ocean models, the results suggest that they will have to be more sophisticated. Some suggestions for next-generation stochastic schemes are made.

If mitigation of black carbon (BC) particulate matter is accompanied by a decrease in particle number emissions, and thereby by a decrease in global cloud condensation nuclei (CCN) concentrations, a decrease in global cloud radiative forcing (a reverse-gcloud albedo effect-h) results. We consider two present-day mitigation scenarios: 50% reduction of primary black carbon/organic carbon (BC/OC) mass and number emissions from fossil fuel combustion (termed HF), and 50% reduction of primary BC/OC mass and number emissions from all primary carbonaceous sources (fossil fuel, domestic biofuel, and biomass burning) (termed HC). Radiative forcing effects of these scenarios are assessed through present-day equilibrium climate simulations. Global average top-of-the- atmosphere changes in radiative forcing for the two scenarios, relative to present day conditions, are +0.13-2 0.33 W m.2 (HF) and + 0.31 ±0.33 W m.-2 (HC). Copyright © 2010 by the American Geophysical Union.

While perhaps the most obvious, ice retreat is just one aspect of a changing Arctic system. The Arctic Ocean is also undergoing unprecedented modifications, that mostly affect its heat and freshwater budgets. As the signal of Arctic change is expected to have its major climatic impact by reaching south the subarctic seas, on either side of Greenland, to modulate the Atlantic thermohaline circulation, the objective of this thesis is to investigate the variability of the exports of volume, heat, freshwater and sea-ice from the Arctic Ocean to the North Atlantic. First, a realistic simulation from 1958 to 2002 run with a global ocean/sea-ice model is used to investigate some aspects of the variability of the Arctic freshwater budget, trying to understand which component of the balance is responsible for the variability of the Arctic freshwater content. We also examine the variability of the freshwater exports to the North Atlantic and we find that this variability is controlled differently on both sides of Greenland: whilst freshwater transport variations across Davis Strait are completely determined by the variations of the total volume flux, the salinity variations due to the ice ocean flux north of Greenland are responsible for a significant part of the freshwater export variability through Fram Strait. Afterward, a simulation run with a fully assimilated model of the very recent period is used to explore the possible consequences of the 2007 sea ice extent minimum on the Arctic Ocean freshwater content. Then, the origins of the water masses exported from the Arctic to the North Atlantic along both sides of Greenland are investigated, using an original numerical method. A quantitative Lagrangian analysis is applied to the monthly climatological 3D output of a global ocean/sea-ice high resolution model. It allows quantification of the different branches of the export to the North Atlantic, as well as related timescales and water mass transformations. A complete and coherent scheme of circulation for the Arctic is proposed, and the role of the Barents Sea for the transformation of the Atlantic inflow is emphasized. Last, we examine the relative influences of the different atmospheric fields (wind stress, heat and salt flux) on the variability of the Arctic sea ice volume. Sensitivity experiments run with a regional Arctic/North Atlantic model allow to investigate the spatial and temporal distributions of these influences., C'est sans doute en Arctique que le changement climatique est le plus visible, et semble affecter toutes les composantes du système Arctique, et notamment ses bilans d'eau douce et de chaleur. Alors que l'on s'attend à ce que le signal d'un changement local en Arctique ait son impact climatique le plus important lorsqu'il est exporté au sud d'un coté ou de l'autre du Groenland vers les mers subarctiques, où il peut moduler l'intensité de la circulation thermohaline, l'objectif de cette thèse est donc d'étudier les échanges de volume, de chaleur, d'eau douce et de glace de l'Océan Arctique vers l'Atlantique Nord. Tout d'abord, une simulation réaliste des années 1958 à 2002 basée sur un modèle global couplé glace/océan est utilisée pour étudier la variabilité du bilan d'eau douce en Arctique, afin de comprendre quelle composante de ce bilan contrôle les variations du contenu halin du bassin. On s'intéresse également à la variabilité des exports d'eau douce vers l'Atlantique Nord, et on montre que les exports d'eau douce vers l'Atlantique sont contrôlés par des mécanismes différents de part et d'autre du Groenland: dans les détroits canadiens, le transport de volume domine la variabilité, alors que salinité et courants contribuent à la variabilité dans le détroit de Fram. Par la suite, une réanalyse océanique des années récentes nous permet d'explorer les conséquences pour le contenu halin de l'Arctique du minimum record de l'extension de glace de l'été 2007. Une méthode numérique originale est ensuite utilisée pour comprendre l'origine des masses d'eau qui sont exportées de l'Arctique vers l'Atlantique Nord. On effectue ainsi une analyse lagrangienne qualitative à partir des sorties 3D mensuelles climatologiques d'un modèle global couplé glace/océan à haute résolution, qui permet de quantifier les contributions relatives des différentes branches de circulation à ces exports, ainsi que les échelles de temps et les transformations de masses d'eau associées. Un schéma complet de la circulation dans le bassin Arctique est ainsi proposé, et nous soulignons le rôle clé de la mer de Barents pour les transformations des eaux d'origine Atlantique. Enfin, nous examinons l'influence relative des différents forçages atmosphériques (vent, flux de chaleur et halins) sur les variations du volume de glace en Arctique. Des expériences de sensibilité sont réalisées à l'aide d'un modèle régional de l'Arctique et l'Atlantique Nord, permettant de mieux comprendre les distributions spatiales et temporelles des contributions des différents forçages atmosphériques.

The aim of this chapter is to introduce the main topics in the Mediterranean circulation research and to give a general description of the Mediterranean Sea variability. Its scope is to provide information that is important for a comprehensive view of the most relevant issues concerning climate, which is a coupling between atmosphere and sea. The chapter describes data, research results, and key findings that have been reported in the most recent literature about the Mediterranean Sea circulation. The issue about sea level is considered in Chapter 4. The chapter also includes, in its concluding section, a discussion of the main open issues in Mediterranean Sea research.

The Chesapeake and Delaware Canal is a man-made waterway connecting the head of the Chesapeake Bay and the upper reaches of the Delaware estuary. We found significant subtidal variability along the canal during a 1-month survey in 1975. There were significant differences between subtidal sea level fluctuations at the two ends of the canal, reflecting the different response characteristics of the two adjoining estuaries to atmospheric forcing. The resulting hydraulic head along the canal forced energetic subtidal volume flux through the canal which was of the same order of magnitude as the Delaware River discharge during the spring freshet period.

Following a period of weak winds, an air-dropped expendable bathythermograph (AXBT) survey on July 4, 1980 showed the Alboran Sea Gyre clearly present at 100-m depth but not at the surface. Winds on July 5 and 6 were from the west at >12 m/s, and both AXBT temperature distributions and satellite images then showed the gyre clearly dominating the temperature structure both at 100 m and at the surface. The disparity between the surface and 100-m temperature patterns on July 4 demonstrates that caution must be used when interpreting satellite imagery in the Alboran Sea (which has been used by several investigators as representing the gyre's structure). The change in the shallow temperature distribution from July 4 to 6 is opposite to what some investigators have proposed as the normal response of the gyre to atmospheric forcing.

The Coastal Ocean Dynamics Experiment (CODE) was designed to identify and study those dynamical processes which govern the wind-driven motion of water over the continental shelf. The initial effort in this multiyear, multi-institutional research program was to obtain high-quality data sets of all the relevant physical variables needed to construct accurate kinematic and dynamic descriptions of the response of continental shelf waters to strong wind forcing in the synoptic band covering 2- to 20-day variability. Two small-scale, densely instrumented field experiments, each approximately 4 months long, were conducted in spring and summer 1981 (CODE 1) and 1982 (CODE 2). A more sparsely instrumented, long-term, large-scale component was also conducted in conjunction with a separate but related Large-Scale West Coast Shelf Experiment (informally called “SuperCODE”) to help separate the local wind-driven response in the region of the small-scale experiments from motions generated in some distant region along the coast and to investigate the seasonal cycles of atmospheric forcing, water structure, and coastal currents between 35° and 48°N.

Oceanic fronts are dynamical phenomena with many properties in common with atmospheric fronts. Fronts are the locus of intense horizontal gradients in one or more properties. Oceanic fronts are generated by atmospheric forcing (momentum, heat, and mass transfer), river runoff, and differential advection and mixing. Mixing is intense in fronts; thus, persistent fronts must be maintained through convergent flows. Typically, fronts have strong thermal and haline gradients. Depending upon the relative signs of these gradients, thermohaline fronts are “density‐reinforced fronts” (or, simply “density fronts”) or “density‐compensated fronts.” These two classes of fronts differ in their dynamics and, thus, flow fields. Sound speed fronts accompany thermal fronts, which leads to strong acoustic refraction across oceanic fronts. Because of the convergent flow, organic and inorganic particles are concentrated at fronts, leading to aggregation of phytoplankton, zooplankton, fish, and marine mammals and birds. Hence, ...

Robert A. Weller is a seagoing experimentalist or observational oceanographer who has made in his short career several truly outstanding contributions to understanding how the upper ocean responds to atmospheric forcing. He is without doubt one of the most capable and creative oceanographers of his age and deserves the recognition provided by the James B. Macelwane Award as a “young geophysicist of outstanding ability and promise.” After receiving his undergraduate degree in engineering a n d applied physics from Harvard, Bob Weller entered graduate school in physical oceanography at Scripps Institution of Oceanography and worked with Russ Davis on the development of a new mechanical current meter to be used in upper ocean studies. While several current meter designs then in use worked well on subsurface moorings in the d e e p ocean, no existing current meter performed well in the upper ocean. After considerable experimental effort, Bob developed a mechanical flow sensor (using two coupled propellers) with nearly perfect cosine response and then used two of these sensors mounted at right angles with associated electronics to build the vector-measuring current meter (or VMCM). By mechanically filtering out the usually very large oscillatory flows with periods less than a minute associated with surface wave and wave-induced mooring motion, the VMCM allows accurate measurement of the generally smaller lowerfrequency horizontal velocities present in the upper ocean. Weller and Davis received a patent for this novel instrument design, and a commercial version has been in production since 1981. Bob has continued to make improvements in the VMCM, and this instrument has become the standard for both upper ocean and coastal ocean circulation studies.