Air-Sea Interaction

1] Using observed data sets mainly for the period 1979-2005, we find that anomalous warming events different from conventional El Niño events occur in the central equatorial Pacific. This unique warming in the central equatorial Pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly (SSTA) on both sides along the equator. empirical orthogonal function (EOF) analysis of monthly tropical Pacific SSTA shows that these events are represented by the second mode that explains 12% of the variance. Since a majority of such events are not part of El Niño evolution, the phenomenon is named as El Niño Modoki (pseudo-El Niño) (''Modoki'' is a classical Japanese word, which means ''a similar but different thing''). The El Niño Modoki involves ocean-atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution, analogous to the Southern Oscillation in the case of El Niño. Hence the total entity is named as El Niño-Southern Oscillation (ENSO) Modoki. The ENSO Modoki events significantly influence the temperature and precipitation over many parts of the globe. Depending on the season, the impacts over regions such as the Far East including Japan, New Zealand, western coast of United States, etc., are opposite to those of the conventional ENSO. The difference maps between the two periods of 1979-2004 and 1958-1978 for various oceanic/atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline. This appears to be a cause of more frequent and persistent occurrence of the ENSO Modoki event during recent decades.

This study examines societal risks and vulnerabilities to the twin disasters of floods and landslides in
Brunei Darussalam from a scientific perspective. Having observed that floods and landslides heavily
impact on communities across the country, damaging property, infrastructure and the natural/built
environment, causing evacuations and other socio-economic disruptions, the study is based on the
premise that only through a good understanding of the underlying forcing mechanisms and triggers can
effective policy disaster risk reduction (DRR) be achieved. Based on the results, the following
observations are established:
1. Floods and landslides in Brunei Darussalam which generally occur during the N.E Monsoon season are
particularly severe in the month of January;
2. Based on the cases of January 2009, 2011 and 2014, it is establishes that although the monsoons are
generally predictable, anomalous episodic deluge which is the primary trigger of floods and landslides is
largely unpredictable;
3. Intense/episodic anomalous rainfall which triggers floods, flash-floods and landslides in Brunei, is
generally forced by an anomalous synoptic air-sea coupled processes and tele-connections across the
marginal South China Sea and adjacent seas;
4). Air-sea coupled mechanisms which force anomalous rainfall are characterized by a high degree of
inter-annual variability and unpredictability.
The study concludes that challenges based on such unpredictability and complexity present a real test to
of meteorologically-induced disaster preparedness in the country and limit management
effectiveness basically to response rather than the more desirable prediction and mitigation.

Measuring and forecasting ocean waves are key elements of marine services. This has stimulated the continuing development of observational networks and operational forecasting systems. But waves are also highly relevant for all other modules of GOOS, in particular for the Climate Module. So far the importance of ocean wave observations for the GOOS Climate Module has been somewhat overlooked. However, sea state is an important element of the coupled atmosphere/ocean system, affecting many human activities. Knowledge of its climatology is of great importance therefore, and its variability on interannual and decadal time scales should be studied, understood, predicted -to the extent possible -and validated. In addition, there are indications that waves can play a dynamical role in the climate system: they affect air-sea interaction, so that the sea state is a parameter in flux parameterizations, and they have a strong effect on the albedo. Waves also affect mass exchange across the sea surface. GOOS wave observations must build on the existing infrastructure, which was originally set up mainly in relation to real-time wave forecasting. Visual observations from ships, instrumental in situ measurements of significant wave height and of the wave spectrum, and satellite observations of waves and wind (altimeter, SAR and scatterometer) are complementing each other and deserve high priority. The analysis of long-term global satellite datasets can complement information obtained from operational model archives (analysis and reanalysis) of assimilated wind and wave fields. To obtain the best possible input observations from existing networks should be distributed through GTS, and additional wave sensors should be standard on all operational moored buoys (e.g. TAO, TRITON, PIRATA, etc). The present paper begins with an overview of the status of wave observation, and wave prediction and specific climate issues. It also discusses the overlap with other modules of GOOS. It is suggested that the WMO CMM Subgroup on Wave Modelling, now part of JCOMM, be given the task of overviewing all wave-related GOOS activities, and that s scientific group, perhaps under SCOR, be established to address some or all of the scientific issues addressed in this paper.

circulations and cloud cover will be assessed. The atmospheric response is known to create small-scale wind stress curl and divergence anomalies, and a discussion of the feedback of these features onto the ocean will also be presented. These processes will be compared and contrasted for different regions such as the Equatorial Front in the Eastern Pacific, and oceanic fronts in mid-latitudes such as the Gulf Stream, Kuroshio, and Agulhas Return Current.

In the Humboldt Current System (HCS), biological and non-biological components, ecosystem processes, and fisheries are known to be affected by multi-decadal, inter-annual, annual, and intra-seasonal scales. The interplay between atmospheric variability, the poleward undercurrent, the shallow oxygen minimum zone (OMZ), and the fertilizing effect of coastal upwelling and overall high primary production rates drive bio-physical interactions, the carbon biomass, and fluxes of gases and particulate and dissolved matter through the water column. Coastal upwelling (permanent and seasonally modulated off Peru and northern Chile, and markedly seasonal between 30°S and 40°S) is the key process responsible for the high biological productivity in the HCS.

Very accurate thermodynamic potential functions are available for fluid water, ice, seawater and humid air covering wide ranges of temperature and pressure conditions. They permit the consistent computation of all equilibrium properties as, for example, required for coupled atmosphereocean models or the analysis of observational or experimental data. With the exception of humid air, these potential functions are already formulated as international standards released by the International Association for the Properties of Water and Steam (IAPWS), and have been adopted in 2009 for oceanography by IOC/UNESCO.

An understanding of the major governing processes of North American monsoon (NAM) is necessary to guide improvement in global and regional climate modeling of the NAM, as well as NAM's impacts on the summer circulation, precipitation and drought over North America. A mechanistic understanding of the NAM is suggested by incorporating local- and synoptic- scale processes. The local scale mechanism describes the effect of the temperature inversion over the Gulf of California (GC) on controlling low-level moisture during the 2004 NAM. The strong low-level inversion inhibits the exchange between the moist air in the marine boundary layer (MBL) and the overlying dry air. This inversion weakens with increasing sea surface temperatures (SSTs) in GC and generally disappears once SSTs exceed 29.5 °C, allowing the moist air, trapped in the MBL, to mix with free tropospheric air. This leads to a deep, moist layer that can be transported by across-gulf (along-gulf) flow towards the NAM core region (southwestern US) to form thunderstorms. On the synoptic scale, climatologies from 1983 to 2010 exhibit a temporal correspondence between coastal warm tropical surface water (TSW), NAM deep convection, NAM anticyclone center and NAM-induced strong descent. A hypothesis is proposed to explain this correspondence, based on limited soundings at the GC entrance (suggesting this local mechanism may also be active in that region), the climatologies and the relevant literature. The warmest SSTs moving up the coast may initiate NAM convection and atmospheric heating, advancing the position of the anticyclone and the region of descent northwards.

This study examines the interannual variability of rainfall in western equatorial Africa and its links to sea-surface temperatures (SSTs). Five geographical regions within the latitudes 10°N-5°S are delineated for the analysis. The links to SSTs in the tropical Atlantic, Pacific and Indian Oceans are examined via seasonal composites of wet and dry years and via linear correlations.

An unusually intense subsynoptic-scale cyclone has been documented in southeastern Italy on 26 September 2006. Numerical simulations are performed with the Weather Research and Forecasting model (WRF). Model results show that the model is able to realistically capture the timing and intensity of the cyclone, identifying in this small-scale cyclone the typical characteristics of a Mediterranean tropical-like cyclone. Sensitivity experiments to sea surface temperature (SST) of the simulated cyclone are discussed in the present paper. In these experiments the SST was changed by a constant few degrees uniformly throughout the Mediterranean Sea. The simulated-cyclone sensitivity to SST is studied in the framework of an air-sea interaction theory, in particular during the two phases that are fundamental for the development of an environment favorable to severe convection and thus for the cyclone to be self-sustained. The modifications of the properties of the simulated cyclones are then analyzed using an objective evaluation, based on a phase diagram used to study the tropical-extratropical transition of cyclones. The present simulations show that the features typical of a tropical cyclone are progressively lost as the SST is reduced. In the colder SST experiments, the lower intensity of the sea-surface fluxes has the effect of delaying and reducing the development of convection and the intensification of the cyclone, so that the cyclone loses the characteristics of a tropical cyclone when SST is reduced by more than 4°C. On the other hand, the cyclone shows a pressure minimum deeper than the control run, with a persistent symmetric warm core, for SST increased by more than 2°C. Finally, when SST is changed by less than 2°C, the cyclone depth and trajectory are not significantly affected by the change in SST and, like the control run, show tropical-like features only for a limited period.

We review what is known about the convective process in the open ocean, in which the properties of large volumes of water are changed by intermittent, deep-reaching convection, triggered by winter storms. Observational, laboratory, and modeling studies reveal a fascinating and complex interplay of convective and geostrophic scales, the large-scale circulation of the ocean, and the prevailing meteorology. Two aspects make ocean convection interesting from a theoretical point of view. First, the timescales of the convective process in the ocean are sufficiently long that it may be modified by the Earth's rotation; second, the convective process is localized in space so that vertical buoyancy transfer by upright convection can give way to slantwise transfer by baroclinic instability. Moreover, the convective and geostrophic scales are not very disparate from one another. Detailed observations of the process in the Labrador, Greenland, and Mediterranean Seas are described, which were made possible by new observing technology. When interpreted in terms of underlying dynamics and theory and the context provided by laboratory and numerical experiments of rotating convection, great progress in our description and understanding of the processes at work is being made.

Changing patterns of correlations between the historical average June-November Southern Oscillation Index (SOI) and October-March precipitation totals for 84 climate divisions in the western US indicate a large amount of variability in SOI/precipitation relations on decadal time scales. Correlations of western US precipitation with SO1 and other indices of tropical El Nifio-Southern Oscillation (ENSO) processes were much weaker from 1920 to 1950 than during recent decades. This variability in teleconnections is associated with the character of tropical air-sea interactions as indexed by the number of out-of-phase SOI/tropical sea surface temperature (SST) episodes, and with decadal variability in the North Pacific Ocean as indexed by the Pacific Decadal Oscillation (PDO). ENSO teleconnections with precipitation in the western US are strong when SO1 and NIN03 are out-of-phase and PDO is negative. ENSO teleconnections are weak when SO1 and NIN03 are weakly correlated and PDO is positive. Decadal modes of tropical and North Pacific Ocean climate variability are important indicators of periods when ENSO indices, like SOI, can be used as reliable predictors of winter precipitation in the US. Copyright 0 1999 Royal Meteorological Society.

The effects of air-sea coupling over the tropical Indian Ocean (TIO) on the eastward-and northward-propagating boreal summer intraseasonal oscillation (BSISO) are investigated by comparing a fully coupled (CTL) and a partially decoupled Indian Ocean (pdIO) experiment using SINTEX-F coupled GCM. Air-sea coupling over the TIO significantly enhances the intensity of both the eastward and northward propagations of the BSISO. The maximum spectrum differences of the northward-(eastward-) propagating BSISO between the CTL and pdIO reach 30% (25%) of their respective climatological values. The enhanced eastward (northward) propagation is related to the zonal (meridional) asymmetry of sea surface temperature anomaly (SSTA). A positive SSTA appears to the east (north) of the BSISO convection, which may positively feed back to the BSISO convection. In addition, air-sea coupling may enhance the northward propagation through the changes of the mean vertical wind shear and low-level specific humidity. The interannual variations of the TIO regulate the air-sea interaction effect. Air-sea coupling enhances (reduces) the eastward-propagating spectrum during the negative Indian Ocean dipole (IOD) mode, positive Indian Ocean basin (IOB) mode and normal years (during positive IOD and negative IOB years). Such phase dependence is attributed to the role of the background mean westerly in affecting the wind-evaporation-SST feedback. A climatological weak westerly in the equatorial Indian Ocean can be readily reversed by anomalous zonal SST gradients during the positive IOD and negative IOB events. Although the SSTA is always positive to the northeast of the BSISO convection for all interannual modes, air-sea coupling reduces the zonal asymmetry of the low-level specific humidity and thus the eastward propagation spectrum during the positive IOD and negative IOB modes, while strengthening them during the other modes. Air-sea coupling enhances the northward propagation under all interannual modes due to the persistent westerly monsoon flow over the northern Indian Ocean.

Corals of the Hawaiian Archipelago are well situated in the North Pacific Gyre (NPG) to record how bomb-produced radiocarbon has been sequestered and transported by the sea. While this signal can be traced accurately through time in reef-building corals and used to infer oceanographic processes and determine the ages of marine organisms, a comprehensive and validated record has been lacking for the Hawaiian Archipelago. In this study, a coral core from Kure Atoll in the northwestern Hawaiian Islands was used to create a high-resolution bomb 14 C record for the years 1939–2002, and was then used with other 14 C measurements in fish otoliths and seawater to explore differences and similarities in the bomb 14 C signal throughout the Hawaiian Archipelago. The Kure Atoll sample series produced a well-defined bomb 14 C curve that, with some exceptions, was similar to other coral 14 C records from the Hawaiian Archipelago. Subtle differences in the coral 14 C records across the region may be explained by the large-scale ocean circulation patterns and decadal cycles of the NPG. The most rapid increase of 14 C, in the 1950s and 1960s, showed similar timing across the Hawaiian Archipelago and provides a robust basis for use of bomb 14 C dating to obtain high-precision age determinations of marine organisms. Reference otoliths of juvenile fish demonstrated the use of the post-peak 14 C decline period as a viable reference in the age validation of younger and more recently collected fishes, and effectively extended the utility of bomb 14 C dating to the latest 30 yr.

The South China Sea (SCS) is among areas in the Northwest Pacific most frequented by tropical cyclones (TCs) with intensity reaching a tropical storm or stronger. It is also an area of significant TC genesis. In this study, TC genesis in SCS and its monsoonal variability for 1948-2003 are analyzed. Altogether, in May-September (southwest monsoon period) 157 TC geneses have occurred north of 12°N in SCS, while in October-December (northeast monsoon period) 64 out of 65 TC geneses have happened south of 18°N. It is found that the monsoonal characteristics of the SCS basically determine the region of TC genesis in each monsoon season. Winter TC genesis in the SCS happens over the region where the marine environment satisfies the four criterions on, respectively, the sea surface temperature (SST), mid-troposphere relative humidity, vertical shear of the horizontal winds and low-level atmospheric vorticity. During the summer, as the two criterions on SST and the mid-troposphere relative humidity are satisfied for the whole SCS, TC genesis occurs in the region where both the low-level vorticity and the vertical shear satisfy the criterion. In addition, there is likely more TC genesis in the winter during the onset of La Nina, and more TC genesis in the summer following the onset of El Nino.

1] Waves have many effects on near-surface dynamics: Breaking waves enhance mixing, waves are associated with a Lagrangian mean drift (the Stokes drift), waves act on the mean flow by creating Langmuir circulations and a return flow opposite to the Stokes drift, and, last but not least, waves modify the atmospheric surface roughness. A realistic ocean model is proposed to embrace all these aspects, focusing on near-surface mixing and surface drift associated with the wind and generated waves. The model is based on the generalized Lagrangian mean that separates the momentum into a wave pseudomomentum and a quasi-Eulerian momentum. A wave spectrum with a reasonably high frequency range is used to compute the Stokes drift. A turbulent closure scheme based on a single evolution equation for the turbulent kinetic energy includes the mixing due to breaking wave effects and wave-turbulence interactions. The roughness length of the closure scheme is adjusted using observations of turbulent kinetic energy near the surface. The model is applied to unstratified and horizontally uniform conditions, showing good agreement with observations of strongly mixed quasi-Eulerian currents near the surface when waves are developed. Model results suggest that a strong surface shear persists in the drift current because of the Stokes drift contribution. In the present model the surface drift only reaches 1.5% of the wind speed. It is argued that stratification and the properties of drifting objects may lead to a supplementary drift as large as 1% of the wind speed. Citation: Rascle, N., F. Ardhuin, and E. A. Terray (2006), Drift and mixing under the ocean surface: A coherent one-dimensional description with application to unstratified conditions,

Theory 1 and modelling 2 predict that hurricane intensity should increase with increasing global mean temperatures, but work on the detection of trends in hurricane activity has focused mostly on their frequency 3,4 and shows no trend. Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multidecadal oscillations in the North Atlantic and North Pacific, and global warming. My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and-taking into account an increasing coastal populationa substantial increase in hurricane-related losses in the twentyfirst century.

Controlled laboratory studies of the physical and chemical properties of sea spray aerosol (SSA) must be under-pinned by a physically and chemically accurate representation of the bubble-mediated production of nascent SSA particles. Bubble bursting is sensitive to the physico-chemical properties of seawater. For a sample of seawater, any important differences in the SSA production mechanism are projected into the composition of the aerosol particles produced. Using direct chemical measurements of SSA at the single-particle level, this study presents an intercomparison of three laboratory-based, bubble-mediated SSA production schemes: gas forced through submerged sintered glass filters ("frits"), a pulsed plunging-waterfall apparatus, and breaking waves in a wave channel filled with natural seawater. The size-resolved chemical composition of SSA particles produced by breaking waves is more similar to particles produced by the plunging waterfall than those produced by sintered glass filters. Aerosol generated by disintegrating foam produced by sintered glass filters contained a larger fraction of organic-enriched particles and a different size-resolved elemental composition, especially in the 0.8–2 μm dry diameter range. Interestingly, chemical differences between the methods only emerged when the particles were chemically analyzed at the single-particle level as a function of size; averaging the elemental composition of all particles across all sizes masked the differences between the SSA samples. When dried, SSA generated by the sintered glass filters had the highest fraction of particles with spherical morphology compared to the more cubic structure expected for pure NaCl particles produced when the particle contains relatively little organic carbon. In addition to an intercomparison of three SSA production methods, the role of the episodic or "pulsed" nature of the waterfall method on SSA composition was under-taken. In organic-enriched seawater, the continuous operation of the plunging waterfall resulted in the accumulation of surface foam and an over-expression of organic matter in SSA particles compared to those produced by a pulsed plunging waterfall. Throughout this set of experiments, comparative differences in the SSA number size distribution were coincident with differences in aerosol particle composition, indicating that the production mechanism of SSA exerts important controls on both the physical and chemical properties of the resulting aerosol with respect to both the internal and external mixing state of particles. This study provides insight into the inextricable physicochemical differences between each of the bubble-mediated SSA generation mechanisms tested and the aerosol particles that they produce, and also serves as a guideline for future laboratory studies of SSA particles.

In the Humboldt Current System (HCS), biological and non-biological components, ecosystem processes, and fisheries are known to be affected by multi-decadal, inter-annual, annual, and intra-seasonal scales. The interplay between atmospheric variability, the poleward undercurrent, the shallow oxygen minimum zone (OMZ), and the fertilizing effect of coastal upwelling and overall high primary production rates drive bio-physical interactions, the carbon biomass, and fluxes of gases and particulate and dissolved matter through the water column. Coastal upwelling (permanent and seasonally modulated off Peru and northern Chile, and markedly seasonal between 30°S and 40°S) is the key process responsible for the high biological productivity in the HCS.

Air-sea interaction at ocean fronts and eddies exhibits positive correlation between sea surface temperature (SST), wind speed, and heat fluxes out of the ocean, indicating that the ocean is forcing the atmosphere. This contrasts with larger scale climate modes where the negative correlations suggest that the atmosphere is driving the system. This paper reviews studies of the interaction of sharp SST gradients and the overlying marine atmospheric boundary layer and deeper atmosphere. The importance of different physical mechanisms of atmospheric response to SST gradients, such as the effect of surface stability variations on momentum transfer, pressure gradients, secondary circulations and cloud cover will be assessed. These processes will be compared and contrasted for different regions such as the Equatorial Front in the Eastern Pacific, and oceanic fronts in mid-latitudes such as the Gulf Stream, Kuroshio, and Agulhas Return Current.

During El Niño-Southern Oscillation (ENSO) events, the atmospheric response to sea surface temperature (SST) anomalies in the equatorial Pacific influences ocean conditions over the remainder of the globe. This connection between ocean basins via the ''atmospheric bridge'' is reviewed through an examination of previous work augmented by analyses of 50 years of data from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis project and coupled atmospheric general circulation (AGCM)-mixed layer ocean model experiments. Observational and modeling studies have now established a clear link between SST anomalies in the equatorial Pacific with those in the North Pacific, north tropical Atlantic, and Indian Oceans in boreal winter and spring. ENSO-related SST anomalies also appear to be robust in the western North Pacific during summer and in the Indian Ocean during fall. While surface heat fluxes are the key component of the atmospheric bridge driving SST anomalies, Ekman transport also creates SST anomalies in the central North Pacific although the full extent of its impact requires further study. The atmospheric bridge not only influences SSTs on interannual timescales but also affects mixed layer depth (MLD), salinity, the seasonal evolution of upper-ocean temperatures, and North Pacific SST variability at lower frequencies. The model results indicate that a significant fraction of the dominant pattern of low-frequency (Ͼ10 yr) SST variability in the North Pacific is associated with tropical forcing. AGCM experiments suggest that the oceanic feedback on the extratropical response to ENSO is complex, but of modest amplitude. Atmosphereocean coupling outside of the tropical Pacific slightly modifies the atmospheric circulation anomalies in the Pacific-North America (PNA) region but these modifications appear to depend on the seasonal cycle and airsea interactions both within and beyond the North Pacific Ocean.

1] The Indian Ocean sea surface temperature (SST) can affect the regional climate in the surrounding regions, including the Indian summer monsoon (ISM) and the Australian summer monsoon (ASM) variability. Recently, it was demonstrated that the in-phase ISM-to-ASM transition can be accomplished through monsoon-Indian Ocean interaction solely. To investigate this issue, a long-term simulation of a hybrid coupled model (HCM) is conducted, in which the atmospheric general circulation model is coupled with a slab ocean model in the Indian Ocean only. Air-sea interactions are allowed only in the tropical Indian Ocean, and the climatological sea surface temperature is specified outside the tropical Indian Ocean. Results from the idealized simulation indicate that the Indian Ocean SST itself can induce in-phase ISM-to-ASM transitions. A wet ISM is largely associated with cool SST in the tropical South Indian Ocean in summer. A wet ASM is also associated with cool SST anomalies in summer. These cool SST anomalies persist until fall and lead to anomalous downward flows over the center of the tropical South Indian Ocean. Consequently, anomalous low-level convergences dominates over northern Australia until winter, which induces a wet ASM. role of air-sea interaction over the Indian Ocean in the in-phase transition from the Indian summer monsoon to the Australian boreal winter monsoon,

1] A recent study shows that the blockage of the southwest monsoon by the mountain range on the east coast of Indochina triggers a chain of ocean-atmospheric response, including a wind jet and cold filament in the South China Sea (SCS). We extend this climatological analysis by using higher temporal resolution (weekly) to study intraseasonal variability in summer. Our analysis shows that the development of the wind jet and cold filament is not a smooth seasonal process but consists of several intraseasonal events each year at about 45-day intervals. In a typical intraseasonal event, the wind jet intensifies to above 12 m/s, followed in a week by the development of a cold filament advected by an offshore jet east of South Vietnam on the boundary of a double gyre circulation in the ocean. The double gyre circulation itself also strengthens in response to the intraseasonal wind event via Rossby wave adjustment, reaching the maximum strength in 2 to 3 weeks. The intraseasonal cold filaments appear to influence the surface wind, reducing the local wind speed because of the increased static stability in the near-surface atmosphere. To first order, the above sequence of events may be viewed as the SCS response to atmospheric intraseasonal wind pulses, which are part of the planetary-scale boreal summer intraseasonal oscillation characterized by the northeastward propagation of atmospheric deep convection. The intraseasonal anomalies of sea surface temperature and precipitation are in phase over the SCS, suggesting an oceanic feedback onto the atmosphere. As wind variations are now being routinely monitored by satellite, the lags of 1-3 weeks in oceanic response offer useful predictability that may be exploited.

Vietnam coast and the offshore spread of cold water are investigated using a suite of new satellite measurements. In summer, as the southwesterly winds impinge on Annam Cordillera-a north-south running mountain range on the east coast of Indochina-a strong wind jet occurs at its southern tip offshore east of Saigon, resulting strong wind curls that are important for ocean upwelling off the coast. In July and August an anticyclonic ocean eddy develops to the southeast advecting the cold coastal water offshore into the open South China Sea (SCS). The center of this cold filament is located consistently north of the wind speed maximum, indicating that open-ocean upwelling helps to cool the ocean surface. Corroborating evidence for the cold filament is found in ocean color observations that reveal a collocated tongue of high chlorophyll concentration. The development of this cold filament disrupts the summer warming of the SCS and causes a pronounced semi-annual cycle in SST. Moreover, the cold filament is an important player in interannual variability in the summer SCS. In 1998, the cold filament and mid-summer cooling never took place, giving rise to a strong basin-wide surface warming. Interannual SST variance has a local maximum over the cold filament, which is much greater than the variance over the adjacent Indian and western Pacific Oceans. A cold filament index is constructed, which displays significant lagged correlation with SST in the eastern equatorial Pacific and Indian Oceans, indicative of a teleconnection from El Nino.

"Antarctic Climate Evolution is the first book dedicated to understanding the history of the world’s largest ice sheet and, in particular, how it responded to and influenced climate change during the Cenozoic. To explain the story of Antarctic ice and climate history, information on terrestrial and marine geology, sedimentology, glacier geophysics, ship-borne geophysics, and numerical ice sheet and climate modelling is presented within thirteen chapters.


The book’s content largely mirrors the structure of the Antarctic Climate Evolution (ACE) program (www.scar-ace.org), an international initiative of the Scientific Committee on Antarctic Research (SCAR), affiliated with the International Polar Year 2007–2009, to investigate past changes in Antarctica by linking climate and ice sheet modelling studies with terrestrial and marine geological and geophysical evidence of past changes.


The programme is designed to determine climate conditions and change in both the recent past (i.e. during the last glacial maximum, when temperatures were cooler than at present) and the more distant past (i.e. in the pre-Quaternary, when global temperature was several degrees higher than it is today). This new cross-disciplinary approach has led to a substantial improvement in the knowledge base on past Antarctic climate and to our understanding of the factors that have guided its evolution. This in turn has allowed us to build hypotheses, examinable through numerical modelling, for how the Antarctic climate is likely to respond to present and future global changes. Most of the subcommittees in ACE have been responsible for individual chapters, and in this way we have been able to cover the complete history of the Antarctic Ice Sheet and its climate evolution. The book will be of interest to research scientists from a wide range of disciplines including glaciology, palaeoclimatology, sedimentology, climate change, environmental science, oceanography and palaeoentology. It will also be valuable as a supplementary text for undergraduate courses.



Fabio Florindo & Martin Siegert


Rome and Edinburgh, July 2008"

In this paper, we review interdecadal climatic variability in the eastern tropical Pacific Ocean. This variability dominates the climatic fluctuations in the North Pacific on scales between ENSO and the centennial trend and is commonly referred to as the Pacific Decadal Oscillation or PDO. We include a historical overview and a summary of observational work that describes the surface, tropospheric and subsurface signatures of this variability. Descriptions of interdecadal variability are incomplete at best, mostly due to limitations in the observational record. We emphasize that the well-known "ENSO-like" sea surface temperature (SST) pattern describing the PDO may not be an accurate representation. In the eastern tropical Pacific, the SST maxima are displaced north and south of the equator with larger amplitudes in the northern branch near the coast of North America, which has significant implications for the tropospheric driven circulations.

Studying the behaviour of the sea surface temperature (SST) is important in the examination of many oceanographic activities. The variations in the SST are mainly controlled by atmospheric conditions. However, other physical parameters are also impacting on these variations, e.g. solar radiation, relative humidity, water depth, groundwater inflow and wind speed. Using a one year (04/02/99-04/02/00) data set, the present paper aims at describing the general behaviour of the daily SST variations within the southeastern Mediterranean Sea region, off the Egyptian Mediterranean coast. The relationships between both the air temperature and wind speed, and the SST were built using regression techniques. The general pattern of the daily SST anomaly, produced in this research, reflects stability and homogeneity in the thermal distribution within the area of study. The seasonal presentation of the SST data reveals normal thermal variation behaviour, e.g. maxima in summer and minima in winter.

The Madden-Julian oscillation (MJO) is the main component of intraseasonal variability of the tropical convection, with clear climatic impacts at an almost-global scale. Based on satellite observations, it is shown that there are two types of austral-summer MJO events (broadly defined as 30-120 days convective variability with eastward propagation of about 5 m/s). Equatorial MJO events have a period of 30-50 days and tend to be symmetric about the equator, whereas MJO events centered near 8°S tend to have a longer period of 55-100 days. The lowerfrequency variability is associated with a strong upperocean response, having a clear signature in both sea surface temperature and its diurnal cycle. These two MJO types have different interannual variations, and are modulated by the Indian Ocean Dipole (IOD). Following a negative IOD event, the lower-frequency southern MJO variability increases, while the higher-frequency equatorial MJO strongly diminishes. We propose two possible explanations for this change in properties of the MJO. One possibility is that changes in the background atmospheric circulation after an IOD favour the development of the low-frequency MJO. The other possibility is that the shallower thermocline ridge and mixed layer depth, by enhancing SST intraseasonal variability and thus ocean-atmosphere coupling in the southwest Indian Ocean (the breeding ground of southern MJO onset), favour the lower-frequency southern MJO variability.

Southwest Western Australia (SWWA) has experienced a significant decrease in winter rainfall since the late 1960s. This decrease is unexplained and the resultant problem of reduced water storage has been compounded by the lack of any useful predictive skill at the seasonal time scale. This study uses recent gridded, historical data and simple linear correlation in order to evaluate the importance of links between rainfall and both mean sea level pressure (MSLP) and sea-surface temperature (SST) patterns over the Indian Ocean.

The study compares the simulated poleward migration characteristics of boreal summer intraseasonal oscillations (BSISO) in a suite of coupled ocean-atmospheric model sensitivity integrations. The sensitivity experiments are designed in such a manner to allow full coupling in specific ocean basins but forced by temporally varying monthly climatological sea surface temperature (SST) adopted from the fully coupled model control runs (ES10). While the local air-sea interaction is suppressed in the tropical Indian Ocean and allowed in the other oceans in the ESdI run, it is suppressed in the tropical Pacific and allowed in the other oceans in the ESdP run. Our diagnostics show that the basic mean state in precipitation and easterly vertical shear as well as the BSISO properties remain unchanged due to either inclusion or exclusion of local air-sea interaction. In the presence of realistic easterly vertical shear, the continuous emanation of Rossby waves from the equatorial convection is trapped over the monsoon region that enables the poleward propagation of BSISO anomalies in all the model sensitivity experiments. To explore the internal processes that maintain the tropospheric moisture anomalies ahead of BSISO precipitation anomalies, moisture and moist static energy budgets are performed. In all model experiments, advection of anomalous moisture by climatological winds anchors the moisture anomalies that in turn promote the northward migration of BSISO precipitation. While the results indicate the need for realistic simulation of all aspects of the basic state, our model results need to be taken with caution because in the ECHAM family of coupled models the internal variance at intraseasonal timescales is indeed very high, and therefore local air-sea interactions may not play a pivotal role.

High-resolution data collected from several programs have greatly increased the spatiotemporal resolution of pCO 2 (sw) data in the Bering Sea, and provided the first autumn and winter observations. Using data from 2008 to 2012, monthly climatologies of sea-air CO 2 fluxes for the Bering Sea shelf area from April to December were calculated, and contributions of physical and biological processes to observed monthly sea-air pCO 2 gradients (DpCO 2 ) were investigated. Net efflux of CO 2 was observed during November, December, and April, despite the impact of sea surface cooling on DpCO 2 . Although the Bering Sea was believed to be a moderate to strong atmospheric CO 2 sink, we found that autumn and winter CO 2 effluxes balanced 65% of spring and summer CO 2 uptake. Ice cover reduced sea-air CO 2 fluxes in December, April, and May. Our estimate for ice-cover corrected fluxes suggests the mechanical inhibition of CO 2 flux by seaice cover has only a small impact on the annual scale (<2%). An important data gap still exists for January to March, the period of peak ice cover and the highest expected retardation of the fluxes. By interpolating between December and April using assumptions of the described autumn and winter conditions, we estimate the Bering Sea shelf area is an annual CO 2 sink of 6.8 Tg C yr 21 . With changing climate, we expect warming sea surface temperatures, reduced ice cover, and greater wind speeds with enhanced gas exchange to decrease the size of this CO 2 sink by augmenting conditions favorable for greater wintertime outgassing.

The sea surface temperature (SST) anomaly of the eastern Indian Ocean (EIO) exhibits cold anomalies in the boreal summer or fall during El Niño development years and warm anomalies in winter or spring following the El Niño events. There also tend to be warm anomalies in the boreal summer or fall during La Niña development years and cold anomalies in winter or spring following the La Niña events. The seasonal phase-locking of SST change in the EIO associated with El Niño/Southern Oscillation is linked to the variability of convection over the maritime continent, which induces an atmospheric Rossby wave over the EIO. Local air-sea interaction exerts different effects on SST anomalies, depending on the relationship between the Rossby wave and the mean flow related to the seasonal migration of the buffer zone, which shifts across the equator between summer and winter.

1] Using the Simple Ocean Data Assimilation (SODA), NCEP/NCAR reanalysis and the GISST datasets from 1950 -1999, and an atmosphere-ocean coupled general circulation model, we explored the possible existence of decadal Indian Ocean Dipole (IOD) variability for the first time. We find that there are strong decadal IOD events, and that the time series of the decadal IOD and decadal ENSO indices are not well correlated. The simulated decadal signal of the IOD index is highly correlated with the 20°C isotherm depth anomaly, indicating that ocean dynamics is involved in the decadal IOD. It is also associated with the zonal wind anomaly. We suggest that the decadal IOD in the tropics is interpreted as decadal modulation of the interannual IOD events.

The concentration of water vapor in the marine atmospheric boundary layer (MABL) at the Brazil-Malvinas Confluence
(BMC), in the Southwestern Atlantic Ocean, was analyzed using data taken during ten oceanographic cruises conducted during the
months of October to November in 2004 to 2015. Previous works had shown that this region, known for its intense horizontal gradients
of sea surface temperature (SST), is responsible for the local modulation of CLAM and for the maintenance of intense lateral gradients
of latent and sensible heat flows between the atmosphere and the ocean. Our results show that the thermal gradients between the
warm waters of the Brazil Current (BC) and the cold waters of the Malvinas Current (MC) that meet at the BMC are able to produce
significant differences on the atmospheric water vapor content between both sides of the oceanographic front on the extension of the
MABL. On average over the warm waters of the BC, the MABL is more humid with an average value near 2 g.kg-1 higher than in
the cold region dominated by MC waters. The MABL is locally modulated by the SST as observed in other previous works made
for the same region. The atmospheric transient systems, common in this region of the planet, however, can attenuate or intensify the
concentration of water vapor in the MABL.

Twenty-four years of AVHRR-derived sea surface temperature (SST) data and 35 years of NOCS (V.2) in situ-based SST data were used to investigate the decadal scale variability of this parameter in the Mediterranean Sea in relation to local air-sea interaction and large-scale atmospheric variability. Satellite and in situ-derived data indicate a strong eastward increasing sea surface warming trend from the early 1990s onwards. The satellite-derived mean annual warming rate is about 0.037°C year -1 for the whole basin, about 0.026°C year -1 for the western sub-basin and about 0.042°C year -1 for the eastern sub-basin over 1985-2008. NOCS-derived data indicate similar variability but with lower warming trends for both sub-basins over the same period. The long-term Mediterranean SST spatiotemporal variability is mainly associated with horizontal heat advection variations and an increasing warming of the Atlantic inflow. Analysis of SST and net heat flux interannual variations indicates a negative correlation, with the long-term SST increase, driving a net air-sea heat flux decrease in the Mediterranean Sea through a large increase in the latent heat loss. Empirical orthogonal function (EOF) analysis of the monthly average anomaly satellitederived time series showed that the first EOF mode is associated with a long-term warming trend throughout the whole Mediterranean surface and it is highly correlated with both the Eastern Atlantic (EA) pattern and the Atlantic Multidecadal Oscillation (AMO) index. On the other hand, SST basin-average yearly anomaly and NAO variations show low and not statistically significant correlations of opposite sign for the eastern (negative correlation) and western (positive correlation) sub-basins. However, there seems to be a link between NAO and SST decadal-scale variations that is particularly evidenced in the second EOF mode of SST anomalies. NOCS SST time series show a significant SST rise in the western basin from 1973 to the late 1980s following a large warming of the inflowing surface Atlantic waters and a long-term increase of the NAO index, whereas SST slowly increased in the eastern basin. In the early 1990s, there is an abrupt change from a very high positive to a low NAO phase which coincides with a large change in the SST spatiotemporal variability pattern. This pronounced variability shift is followed by an acceleration of the warming rate in the Mediterranean Sea and a change in the direction (from westward to eastward) of its spatial increasing tendency.

The design of a surface mooring for deployment in the Gulf Stream in the Mid-Atlantic Bight is described. The authors' goals were to observe the surface meteorology; upper-ocean variability; and air–sea exchanges of heat, freshwater, and momentum in and near the Gulf Stream during two successive 1-yr deployments. Of particular interest was quantifying these air–sea fluxes during wintertime events that carry cold, dry air from the land over the Gulf Stream. Historical current data and information about the surface waves were used to guide the design of the surface mooring. The surface buoy provided the platform for both bulk meteorological sensors and a direct covariance flux system. Redundancy in the meteorological sensors proved to be a largely successful strategy to obtain complete time series. Oceanographic instrumentation was limited in size by considerations of drag; and two current meters, three temperature–salinity recorders, and 15 temperature recorders were deployed. Deployment from a single-screw vessel in the Gulf Stream required a controlled-drift stern first over the anchor sites. The first deployment lasted the planned full year. The second deployment ended after 3 months when the mooring was cut by unknown means at a depth of about 3000 m. The mooring was at times in the core of the Gulf Stream, and a peak surface current of over 2.7 m s 21 was observed. The 15-month records of surface meteorology and air–sea fluxes captured the seasonal variability as well as several cold-air outbreaks; the peak observed heat loss was in excess of 1400 W m 22 .

We present an atmosphere-ocean regional climate model for the Mediterranean basin, called the PRO-THEUS system, composed by the regional climate model RegCM3 as the atmospheric component and by a regional configuration of the MITgcm model as the oceanic component. The model is applied to an area encompassing the Mediterranean Sea and compared to a stand-alone version of its atmospheric component. An assessment of the model performances is done by using available observational datasets. Despite a persistent bias, the PROTHEUS system is able to capture the inter-annual variability of seasonal sea surface temperature (SST) and also the fine scale spatio-temporal evolution of observed SST anomalies, with spatial correlation as high as 0.7 during summer. The close inspection of a 10-day strong wind event during the summer of 2000 proves the capability of the PROTHEUS system to correctly describe the daily evolution of SST under strong air-sea interaction conditions. As a consequence of the model's skill in reproducing observed SST and wind fields, we expect a reliable estimation of air-sea fluxes. The model skill in reproducing climatological land surface fields is in line with that of state of the art regional climate models.

The chemical composition of salt water profoundly alters the process of microbubble formation and must be accounted for in extrapolating freshwater results to the ocean environment. Results are presented of the measurement of bubble size distributions generated by breaking waves in both freshwater and saltwater laboratory tanks. Bubble radii in the range of 34-1200/~m were measured by an acoustic resonator at various positions and depths in a large-scale wave tank at Oregon State University. This experiment represents the first attempt to measure bubbles produced by breaking waves at this large scale in a saltwater tank. Mechanically generated wave groups, with maximum wave height of 4 ft, were used to produce breaking waves and bubble plumes comparable in scale with moderate ocean waves. During the experiment salt was added to bring the salinity of the water to 30%0. This salinity alters the nature of the bubbles produced and their subsequent evolution. An order of magnitude increase in the number density over the entire size range was observed for salt water vs. fresh water.

This paper investigates the role that air-sea interaction processes may play in interannual variability of south-eastern African summer rainfall. The principal spatial modes of south-eastern African summer rainfall are first identified using principal component analysis. Four modes are retained. The most important mode of variability is found to represent rainfall variability over most of the domain, particularly in the regions to the south.

The mutual consistency of the Seasat global data sets of scatterometer winds and altimeter wave heights is investigated for the complete Seasat period using the third-generation wave model WAM. The wave model was driven by surface (1000 hPa) wind and surface stress fields constructed by the Goddard Laboratory for Atmospheres (GLA) by assimilation of the scatterometer winds in an atmospheric model. For the 10-day period September 7-17 the intercomparison was extended to two further scatterometer wind fields: a 1000-hPa assimilated wind field from the European Centre for Medium-Range Weather Forecasts and a subjectively analyzed 19.5-m-height surface wind field from the Jet Propulsion Laboratory. On the global average, the modeled and observed wave heights agree reasonably well. Regional differences, however, can be large and sometimes exceed 40%. The errors are attributed mainly to deficiencies in the forcing wind fields. Low wind speeds are found to be overestimated and high wind speeds underestimated by the Seasat scatterometer algorithm. The friction velocities of the GLA model are found to be significantly underestimated in the high-wind belt of the southern hemisphere. The analysis demonstrates the diagnostic advantages of applying a wave model for the quality assessment of satellite wind and wave data. A preliminary wave data assimilation scheme is presented in which the wave field is updated without changing the forcing wind field. A considerable improvement of the computed wave field is achieved, particularly in regions in which the wave energy is dominated by swell. However, a more general assimilation scheme including modifications of the wind field is needed to upgrade wind sea forecasts.

1] Estuarine near-surface turbulence is important for transport, mixing, and air-water exchanges of many important constituents but has rarely been studied in detail. Here, we analyze a unique set of estuarine observations of in situ atmospheric and full water column measurements, estimated air-sea exchanges, and acoustic measurements of several terms in the turbulent kinetic energy (TKE) budget. Observations from a 5.1 m deep site in the Hudson River estuary include dissipation at 50 cm depth (" 50 ), as well as profiles of TKE, shear production of TKE (P), and net turbulent vertical TKE transport (T D ). Regressions suggest that the principal controlling factor for " 50 was wind (through the surface shear velocity, U * ) and that the surface heat flux and tidal currents played a secondary role. For ebb spring tides, the TKE budget at 50 cm depth was closed within noise levels. Ebbs had high " 50 due to local shear production, which nearly balanced " 50 . Floods had T D approaching P in the upper water column but generally weak near-surface shear and turbulence. Examining buoyancy fluxes that impact near-surface stratification and can indirectly control turbulence, solar heat input and tidal straining caused similar buoyancy fluxes on a sunny, calm weather day, promoting ebb tide restratification. Wind-driven mixing was found to dominate during a fall season storm event, and strong overnight heat loss after the storm helped delay restratification afterward. These results demonstrate the utility of combining detailed air-sea interaction and physical oceanographic measurements in future estuary studies.