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The article presents a research study of the Galápagos Island and its effect on the El Nião-Southern Oscillation (ENSO). ENSO is considered as one of the climate oscillations on Earth. The researchers used an ocean general circulating model and a hybrid coupled model of the tropical Pacific Ocean to examine the effects of the Galápagos Island on ENSO. Results such as the shift lead by the island in the ENSO period from biennial to quasi-quadrinneal are presented. Also, further studies in relation to the subject are encouraged.

Despite decades of efforts and improvements in the representation of processes as well as in model resolution, current global climate models still suffer from a set of important, systematic biases in sea surface temperature (SST), not much different from the previous generation of climate models. Many studies have looked at errors in the wind field, cloud representation or oceanic upwelling in coupled models to explain the SST errors. In this paper we highlight the relationship between latent heat flux (LH) biases in forced atmospheric simulations and the SST biases models develop in coupled mode, at the scale of the entire intertropical domain. By analyzing 22 pairs of forced atmospheric and coupled ocean-atmosphere simulations from the CMIP5 database, we show a systematic, negative correlation between the spatial patterns of these two biases. This link between forced and coupled bias patterns is also confirmed by two sets of dedicated sensitivity experiments with the IPSL-CM5A-LR model. The analysis of the sources of the atmospheric LH bias pattern reveals that the near-surface wind speed bias dominates the zonal structure of the LH bias and that the near-surface relative humidity dominates the east-west contrasts. [ABSTRACT FROM AUTHOR]

This paper aims at identifying oceanic regions outside the tropical Pacific, which may influence the El Niño Southern Oscillation (ENSO) through interannual modulation of equatorial Pacific winds. An Atmospheric General Circulation Model (AGCM) 7-members ensemble experiment forced by climatological sea surface temperature (hereafter, SST) in the tropical Pacific Ocean and observed interannually varying SST elsewhere produces ensemble-mean equatorial zonal wind stress interannual anomalies (ZWSA) over the equatorial Pacific. These ZWSA are largest during boreal winter in the western Pacific, and induce a ~0.5 °C response in the central Pacific during the following spring in a simple ocean model, that weakly but significantly correlates with the following ENSO peak amplitude. When correlated with global SST, the residual western equatorial Pacific ZWSA yield SST patterns that are reminiscent of ENSO teleconnections in the Indian, North and South Pacific, and Atlantic Oceans. We further design 20-members ensemble sensitivity experiments forced by typical SST patterns of the main climate modes for each of these regions, in order to identify regions that influence equatorial Pacific ZWSA most. In our experiments, only the Indian Ocean Basin-wide SST warming in late boreal winter produces a statistically significant ZWSA in the western equatorial Pacific, resulting in a weak but significant ~0.35 °C SST response in the central Pacific (i.e. ~35 % of the observed standard deviation) during the following spring, the season when the Bjerkness coupled feedback is particularly efficient. This paper hence agrees with previous studies, which suggest that ENSO-induced basin-wide SST signals in the Indian Ocean may contribute to the phase transition of ENSO. Our results suggest that studies exploring external influences on ENSO should adopt a global approach rather than focus on a specific region. Designing coupled model simulations would also allow investigating air-sea interactions-mediated teleconnection mechanisms, which we can't reproduce in our forced AGCM framework. [ABSTRACT FROM AUTHOR]

The dominant interannual El Niño–Southern Oscillation (ENSO) phenomenon and the short length of climate observation records make it difficult to study long-term climate variations in the spatiotemporal domain. Based on the fact that the ENSO signal spreads to remote regions and induces delayed climate variation through atmospheric teleconnections, an ENSO-removal method is developed through which the ENSO signal can be approximately removed at the grid box level from the spatiotemporal field of a climate parameter. After this signal is removed, long-term climate variations are isolated at mid- and low latitudes in the climate parameter fields from observed and reanalysis datasets. This paper addresses the long-term global warming trend (GW); a companion paper concentrates on Pacific pan-decadal variability (PDV). The warming that occurs in the Pacific basin (approximately 0.4 K in the twentieth century) is much weaker than in surrounding regions and the other two ocean basins (approximately 0.8 K). The modest warming in the Pacific basin is likely due to its dynamic nature on the interannual and decadal time scales and/or the leakage of upper ocean water through the Indonesian Throughflow. Based on the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) and the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40), a comprehensive atmospheric structure associated with the GW trend is given. Significant discrepancies exist between the two datasets, especially in the tightly coupled dynamics and water vapor fields. The dynamics fields based on NCEP–NCAR, which show a change in the Walker Circulation, are consistent with the GW change in the surface temperature field. However, intensification in the Hadley Circulation is associated with GW trend in ERA-40 instead. [ABSTRACT FROM AUTHOR]

In this study, the data from three long-term observation stations, Aburatsu, Xiamen, and Hong Kong, which are located on the northwest Pacific Ocean coast, were analyzed to estimate the 100-year annual maximum water levels. The performances of four common frequency analysis methods, namely the Gumbel, Weibull, GEV, and GPD distributions, were evaluated. It is found that the GEV model performs best among these four distribution models in Hong Kong and Aburatsu, whereas the Gumbel distribution is the best at the Xiamen station. It is also found that the GEV model generally performs better than the Gumbel model in regard to the mean high correlation coefficient and the mean minimum root-mean-square error. Moreover, in this study, the r-largest value model was used to study temporal trends in the 50-year annual maximum water levels on the northwest Pacific coast over the past fifty years using the observation data of Hong Kong, Xiamen, and Aburatsu. The results show that there are two temporal features in the 50-year return levels at all three stations, with the first being an overall increasing trend over the whole period and the other being an oscillatory trend over the period of observation. The relationships between the temporal trends and the Pacific Decadal Oscillation (PDO), sea level rise, and change of typhoons were also analyzed in this paper. It is found that when the PDO index is shifted to be 4 years in advance, a significantly negative correlation will occur between the PDO index and the 50-year return levels. However, sea level rise and changes of typhoons cause the overall increase over the entire period. [ABSTRACT FROM AUTHOR]

Using the newly available decade-long Argo data for the period 2004-13, a detailed study is carried out on deriving four-dimensional (4D) modality of sea temperature in the upper ocean with emphasis on its interannual variability in terms of amplitude, phase, and periodicity. Three principal modes with central periodicities at 19.2, 33.8, and 50.3 months have been identified, and their relationship with El Niño-Southern Oscillation (ENSO) is investigated, yielding a number of useful results and conclusions: 1) A striking tick-shaped pipe-like feature of interannual variability maxima, which is named the 'Niño pipe' in this paper, has been revealed within the 10°S-10°N upper Pacific Ocean. 2) The pipe core extends downward from ~50 m at 130°E to ~250 m near the date line before tilting upward to the sea surface at about 275°E, coinciding nicely with the pathway of the Pacific equatorial undercurrent (EUC). 3) The double-peak zonal modality pattern of the Niño pipe in the upper Pacific is echoed in the subsurface Atlantic and Indian Oceans through Walker circulation, while its single-peak meridional modality pattern is mirrored in the subsurface North and South Pacific through Hadley circulation. 4) A coherent three-peak modal structure implies a strong coupling between sea level variability at the surface and sea temperature variability around the thermocline. Accumulating evidence suggests that Rossby/Kelvin wave dynamics in tandem with EUC-based thermocline dynamics are the main mechanisms of the three-mode Niño pipe in ENSO cycles. [ABSTRACT FROM AUTHOR]

A hybrid coupled model (HCM) is constructed for El Niño-Southern Oscillation (ENSO)-related modeling studies over almost the entire Pacific basin. An ocean general circulation model is coupled to a statistical atmospheric model for interannual wind stress anomalies to represent their dominant coupling with sea surface temperatures. In addition, various relevant forcing and feedback processes exist in the region and can affect ENSO in a significant way; their effects are simply represented using historical data and are incorporated into the HCM, including stochastic forcing of atmospheric winds, and feedbacks associated with freshwater flux, ocean biology-induced heating (OBH), and tropical instability waves (TIWs). In addition to its computational efficiency, the advantages of making use of such an HCM enable these related forcing and feedback processes to be represented individually or collectively, allowing their modulating effects on ENSO to be examined in a clean and clear way. In this paper, examples are given to illustrate the ability of the HCM to depict the mean ocean state, the circulation pathways connecting the subtropics and tropics in the western Pacific, and interannual variability associated with ENSO. As satellite data are taken to parameterize processes that are not explicitly represented in the HCM, this work also demonstrates an innovative method of using remotely sensed data for climate modeling. Further model applications related with ENSO modulations by extratropical influences and by various forcings and feedbacks will be presented in Part II of this study. [ABSTRACT FROM AUTHOR]

This paper describes the first use of a stochastic cyclone model (SCM) to quantify the extreme significant wave height from tropical cyclones across the Southwest Pacific Ocean. The median extreme significant wave heights across the entire SW Pacific Ocean were 7.5, 10 and 11 m for annual exceedance probabilities (AEPs) of 0.1, 0.02 and 0.01 respectively. Maximum significant wave heights in the region were approximately 1.5 times these values for the same AEP. Tables of extreme significant wave heights are provided for selected inhabited locations. The SCM was used to quantify the effects of the El Niño-Southern Oscillation (ENSO) on extreme significant wave heights, and also the effects of projected climate change on cyclone intensity and frequency of occurrence. West of the International Dateline in the region of the Vanuatu archipelago, the extreme cyclone wave climate was relatively consistent during all phases of the ENSO cycle, but highest during El Niño. Cyclone formation and propagation eastward of the Dateline are more likely to occur during El Niño conditions, however these cyclones tended to be more intense, particularly during extreme El Niño events, leading to a higher long-term extreme wave climate in the eastern SW Pacific, despite the relatively low cyclone observation rate there. Simulations of climate change cyclone intensity increases of 10–20% of the most intense cyclones (categories 4 and 5) along with 10–20% reduction in number of cyclones indicated little change in extreme significant wave heights for low-occurrence AEPs of 1/20 or less. These changes were much less than induced by present-day ENSO variability, suggesting that future changes in extreme wave climate will be sensitive to climate change influences on the frequency and intensity of ENSO events. These results are significant in the light of indications that the frequency of extreme El Nino events might double in response to greenhouse warming. [ABSTRACT FROM AUTHOR]

Understanding of past climate variability on millennial to decadal scales are of primary importance in order to assess modern processes and predict future climatic events. Past history of Arctic climate changes is currently receiving increasing attention due to the recent phenomena of rapid sea-ice reduction. In this paper, we thoroughly reviewed the Holocene history of spatiotemporal climatic changes in the western Arctic region in order to better understand recent rapid environmental changes occurring in the Pacific sector of the Arctic, and further to discuss critical issues and new perspectives on the western Arctic in terms of paleoclimate researches. Records of temporal and spatial variations in sea-ice extents as well as marine and terrestrial paleoclimatic proxies show a strong asynchronicity between the western and eastern Arctic throughout the Holocene. The reason for this apparent contradiction across the Arctic may be linked to freshwater discharges over the Arctic shelves and the inflow of the Pacific freshwater into the western Arctic Ocean in coupled with a complex interaction between atmospheric and sea-ice dynamics. Special emphasis is placed on a tentative linkage of the late Holocene paleoclimatic events between the Arctic regions and the northwestern Pacific margin, highlighting the notion that climatic events of the northern Pacific Ocean is closely linked to the global climate system through hydrological dynamics in the western Arctic Ocean. [ABSTRACT FROM AUTHOR]

Abstract: Most attempts to link seabirds and climate/oceanographic effects have concerned the Atlantic and Pacific Oceans with comparatively few studies in the tropical Indian Ocean. This paper examines the reproductive response of the lesser noddy Anous tenuirostris to temporal fluctuations in oceanographic and climatic conditions using 8 years of monitoring data from Aride Island (Seychelles), tropical Western Indian Ocean. We tested the hypothesis that breeding parameters (mean hatching date, mean egg size, hatching and fledging successes) and chick growth are influenced by local, seasonal oceanographic conditions as expressed by ocean primary productivity (surface chlorophyll-a concentrations; CC), sea surface temperature (SST) and wind speed. We also examined the relationship between lesser noddy breeding parameters and climate conditions recorded at the basin-wide scale of the Indian Ocean (Indian Ocean Dipole Mode Index, DMI). Our findings suggest that birds had a tendency to lay slightly larger eggs during breeding seasons (years) with higher CC during April–June (pre-laying, laying and incubation periods). Hatching date was positively related to SST in April–June, with the regression parameters suggesting that each 0.5 °C increase in SST meant a delay of approx.10 days in hatching date. A negative linear relationship was also apparent between hatching success and SST in June–August (hatching and chick-rearing periods), while the quadratic regression models detected a significant effect of wind speed in June–August on fledging success. Body mass increments of growing chicks averaged over 7-day periods were positively related with (2-week) lagged CC values and negatively related with (2-week) lagged SST values. No significant relationship between DMI and lesser noddy breeding parameters was found, but DMI indices were strongly correlated with local SST. Altogether, our results indicate that the reproduction of this top marine predator is dictated by fluctuations in local environmental conditions around the colony, while the effects of large-scale oceanographic processes (DMI) on our study population might be mediated by an effect on local SST. [Copyright &y& Elsevier]

The seasonal cycle and interannual variability in the tropical oceans simulated by three versions of the Flexible Ocean-Atmosphere-Land System (FGOALS) model (FGOALS-g1.0, FGOALS-g2 and FGOALSs2), which have participated in phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5), are presented in this paper. The seasonal cycle of SST in the tropical Pacific is realistically reproduced by FGOALS-g2 and FGOALSs2, while it is poorly simulated in FGOALS-g1.0. Three feedback mechanisms responsible for the SST annual cycle in the eastern Pacific are evaluated. The ocean-atmosphere dynamic feedback, which is successfully reproduced by both FGOALS-g2 and FGOALS-s2, plays a key role in determining the SST annual cycle, while the overestimated stratus cloud-SST feedback amplifies the annual cycle in FGOALS-s2. Because of the serious warm bias existing in FGOALS-g1.0, the ocean-atmosphere dynamic feedback is greatly underestimated in FGOALS-g1.0, in which the SST annual cycle is mainly driven by surface solar radiation. FGOALS-g1.0 simulates much stronger ENSO events than observed, whereas FGOALS-g2 and FGOALSs2 successfully simulate the observed ENSO amplitude and period and positive asymmetry, but with less strength. Further ENSO feedback analyses suggest that surface solar radiation feedback is principally responsible for the overestimated ENSO amplitude in FGOALS-g1.0. Both FGOALS-g1.0 and FGOALS-s2 can simulate two different types of El Ni-no events - with maximum SST anomalies in the eastern Pacific (EP) or in the central Pacific (CP) - but FGOALS-g2 is only able to simulate EP El Ni-no, because the negative cloud shortwave forcing feedback by FGOALS-g2 is much stronger than observed in the central Pacific. [ABSTRACT FROM AUTHOR]

In this paper, lead-time and spatial dependence in skill for prediction of monthly mean climate variability is analyzed. The analysis is based on a set of extensive hindcasts from the Climate Forecast System at the National Centers for Environmental Prediction. The skill characteristics of initialized predictions is also compared with the AMIP simulations forced with the observed sea surface temperature (SST) to quantify the role of initial versus boundary conditions in the prediction of monthly means. The analysis is for prediction of monthly mean SST, precipitation, and 200-hPa height. The results show a rapid decay in skill with lead time for the atmospheric variables in the extratropical latitudes. Further, after a lead-time of approximately 30-40 days, the skill of monthly mean prediction is essentially a boundary forced problem, with SST anomalies in the tropical central/eastern Pacific playing a dominant role. Because of the larger contribution from the atmospheric internal variability to monthly time-averages (compared to seasonal averages), skill for monthly mean prediction associated with boundary forcing is also lower. The analysis indicates that the prospects of skillful prediction of monthly means may remain a challenging problem, and may be limited by inherent limits in predictability. [ABSTRACT FROM AUTHOR]

The role of climate variability in determining the fluctuations of fish populations had been a traditional problem in ecology. In this paper, we studied the role of the Southern Oscillation Index (SO) and the Pacific Decadal Oscillation (PDO) on the population dynamics of the western stock of the skipjack tuna Katsuwonus pelamis. Our analysis was based in three sequential steeps: a diagnostic approach to deduce what kind of population dynamic model should be more appropriate, the modelling of capture per unit of effort data through a logistic model, and the use of population dynamic theory for analyzing the effect of exogenous perturbations. We find that direct and one-year lagged negative PDO effects and one-year lagged negative SO effects were needed to explain annual tuna fluctuations. Models including the combined effects of these climatic indexes explain 80% of the variance in tuna fluctuations. In addition, these models provided very accurate predictions of independent skipjack tuna observed dynamics. This result is encouraging because the inherent variability in CPUE data and the not well determined link between climate and ecological processes. Finally, this study demonstrates that simple models can offer reasonable explanations and accurate predictions of tuna fluctuations, provided they are based on a sound theoretical framework. [ABSTRACT FROM AUTHOR]

Most of the annual rainfall over India occurs during the Southwest (June-September) and Northeast (October-December) monsoon periods. In March 2008, however, Southern peninsular India and Sri Lanka received the largest rainfall anomaly on record since 1979, with amplitude comparable to summer-monsoon interannual anomalies. This anomalous rainfall appeared to be modulated at intraseasonal timescale by the Madden Julian Oscillation, and was synchronous with a decaying La Niña event in the Pacific Ocean. Was this a coincidence or indicative of a teleconnection pattern? In this paper, we explore factors controlling rainfall over southern India and Sri Lanka between January and April, i.e. outside of the southwest and northeast monsoons. This period accounts for 20% of annual precipitation over Sri Lanka and 10% over the southern Indian states of Kerala and Tamil Nadu. Interannual variability is strong (about 40% of the January-April climatology). Intraseasonal rainfall anomalies over southern India and Sri Lanka are significantly associated with equatorial eastward propagation, characteristic of the Madden Julian Oscillation. At the interannual timescale, we find a clear connection with El Niño-Southern Oscillation (ENSO); with El Niños being associated with decreased rainfall (correlation of −0.46 significant at the 98% level). There is also a significant link with local SST anomalies over the Indian Ocean, and in particular with the inter-hemispheric sea surface temperature (SST) gradient over the Indian Ocean (with colder SST south of the equator being conducive to more rainfall, correlation of 0.55 significant at the 99% level). La Niñas/cold SSTs south of the equator tend to have a larger impact than El Niños. We discuss two possible mechanisms that could explain these statistical relationships: (1) subsidence over southern India remotely forced by Pacific SST anomalies; (2) impact of ENSO-forced regional Indian Ocean SST anomalies on convection. However, the length of the observational record does not allow distinguishing between these two mechanisms in a statistically significant manner. [ABSTRACT FROM AUTHOR]

In this paper a detailed global climatology of wind-sea and swell parameters, based on the 45-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) wave reanalysis is presented. The spatial pattern of the swell dominance of the earth''s oceans, in terms of the wave field energy balance and wave field characteristics, is also investigated. Statistical analysis shows that the global ocean is strongly dominated by swell waves. The interannual variability of the wind-sea and swell significant wave heights, and how they are related to the resultant significant wave height, is analyzed over the Pacific, Atlantic, and Indian Oceans. The leading modes of variability of wind sea and swell demonstrate noticeable differences, particularly in the Pacific and Atlantic Oceans. During the Northern Hemisphere winter, a strong north--south swell propagation pattern is observed in the Atlantic Ocean. Statistically significant secular increases in the wind-sea and swell significant wave heights are found in the North Pacific and North Atlantic Oceans. [ABSTRACT FROM AUTHOR]

There is growing concern about the effects of large-scale oceanic atmospheric climate variability, such as the Pacific decadal oscillation (PDO), on regional hydrology and water resources. In this paper, the effects of PDO on temporal patterns of winter (January–March) flow in northwestern North America (NWNA), which is believed to be a PDO-sensitive region, is studied for the period 1943–2007 using daily streamflow data from a much larger set of 179 stations, compared to previous studies in which only smaller subsets of these stations were analyzed. Time series of winter flows were divided into two nonoverlapping blocks corresponding to change points detected in time series of December–March mean monthly PDO indices. Both parametric and nonparametric measures of correlation and average percentage differences and average standardized differences from the period-of-record mean were explored. Like some of the previous studies, it is found that, on average, winter flows tend to be higher (lower) during the warm (cold) phase of the PDO and that establishes the physical link between large-scale climate variability and basin response. It is shown that the serial structure of time series of PDO indices conforms to that of a stochastic process with long-term persistence (LTP). Based on this finding and the climate–streamflow physical link, it is plausible to investigate temporal variations in winter flows with the LTP hypothesis, in addition to assuming merely independence (IND) or short-term persistence (STP). The results of the analysis demonstrate that the LTP mechanism, in combination with the STP, is able to explain more than half of the significant trends noted, with the IND assumption suggesting that the significance of trends reported in previous studies in NWNA may have been overstated. This result has important implications for future planning of regional water resources. [ABSTRACT FROM AUTHOR]

An important question in assessing twentieth-century climate change is to what extent have ENSO-related variations contributed to the observed trends. Isolating such contributions is challenging for several reasons, including ambiguities arising from how ENSO itself is defined. In particular, defining ENSO in terms of a single index and ENSO-related variations in terms of regressions on that index, as done in many previous studies, can lead to wrong conclusions. This paper argues that ENSO is best viewed not as a number but as an evolving dynamical process for this purpose. Specifically, ENSO is identified with the four dynamical eigenvectors of tropical SST evolution that are most important in the observed evolution of ENSO events. This definition is used to isolate the ENSO-related component of global SST variations on a month-by-month basis in the 136-yr (1871–2006) Hadley Centre Sea Ice and Sea Surface Temperature dataset (HadISST). The analysis shows that previously identified multidecadal variations in the Pacific, Indian, and Atlantic Oceans all have substantial ENSO components. The long-term warming trends over these oceans are also found to have appreciable ENSO components, in some instances up to 40% of the total trend. The ENSO-unrelated component of 5-yr average SST variations, obtained by removing the ENSO-related component, is interpreted as a combination of anthropogenic, naturally forced, and internally generated coherent multidecadal variations. The following two surprising aspects of these ENSO-unrelated variations are emphasized: 1) a strong cooling trend in the eastern equatorial Pacific Ocean and 2) a nearly zonally symmetric multidecadal tropical–extratropical seesaw that has amplified in recent decades. The latter has played a major role in modulating SSTs over the Indian Ocean. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses large-scale climate variability for several marine ecosystems and suggests types of ecosystem responses to climate change. Our analysis of observations and model results for the Pacific and Atlantic Oceans concludes that most climate variability is accounted for by the combination of intermittent 1–2 year duration events, e.g. the cumulative effect of monthly weather anomalies or the more organized El Niño/La Niña, plus broad-band “red noise” intrinsic variability operating at decadal and longer timescales. While ocean processes such as heat storage and lags due to ocean circulation provide some multi-year memory to the climate system, basic understanding of the mechanisms resulting in observed large decadal variability is lacking and forces the adoption of a “stochastic or red noise” conceptual model of low frequency variability at the present time. Thus we conclude that decadal events with rapid shifts and major departures from climatic means will occur, but their timing cannot be forecast. The responses to climate by biological systems are diverse in character because intervening processes introduce a variety of amplifications, time lags, feedbacks, and non-linearities. Decadal ecosystem variability can involve a variety of climate to ecosystem transfer functions. These can be expected to convert red noise of the physical system to redder (lower frequency) noise of the biological response, but can also convert climatic red noise to more abrupt and discontinuous biological shifts, transient climatic disturbance to prolonged ecosystem recovery, and perhaps transient disturbance to sustained ecosystem regimes. All of these ecosystem response characteristics are likely to be active for at least some locations and time periods, leading to a mix of slow fluctuations, prolonged trends, and step-like changes in ecosystems and fish populations in response to climate change. Climate variables such as temperatures and winds can have strong teleconnections (large spatial covariability) within individual ocean basins, but between-basin teleconnections, and potential climate-driven biological synchrony over several decades, are usually much weaker and a highly intermittent function of the conditions prevailing at the time within the adjoining basins. As noted in the recent IPCC 4th Assessment Report, a warming trend of ocean surface layers and loss of regional sea ice is likely before 2030, due to addition of greenhouse gases. Combined with large continuing natural climate variability, this will stress ecosystems in ways that they have not encountered for at least 100s of years. [Copyright &y& Elsevier]

Abstract: Climate change impacts in large marine ecosystems (LMEs) are driven by global climate variability, often communicated over large distances by atmospheric teleconnections, and modified by the dominant local and regional ocean processes. The focus of this paper is to summarize the key processes and features that characterize the major coastal LMEs of the Pacific, as part of a greater effort to understand the role of past and future global climate change in driving (possibly synchronous) fluctuations in marine populations. The physical setting of five LMEs – the Humboldt Current System (HCS), California Current System (CCS), Gulf of Alaska (GOA), Kuroshio Current System (KCS), and Oyashio Current System (OCS) – and the mechanisms and impacts of climate variability on these systems are described. Because of their pivotal role in linking and perhaps synchronizing climate variability in disparate LMEs, we also review teleconnections and analyze past global atmospheric teleconnections and regional ocean response patterns. The major Pacific eastern boundary current systems, the CCS and HCS, feature similar dominant processes (e.g., coastal upwelling), and share atmospheric forcing from common teleconnection patterns that vary together. Sea level pressure variations forcing the KCS and OCS systems on climate scales, however, are not strongly teleconnected to the CCS and HCS. A common factor analysis of sea surface temperature (SST) within these ecosystems provides an example of how LMEs have responded to past climate variability. All LMEs display a persistent warming tendency since 1900, with multi-decadal fluctuations superimposed. However, SST fluctuations in the western Pacific lag those in the east by about a decade. Global synchrony in climate forcing is modulated by distinct processes within each LME, which reduce the correlation between long-term fluctuations. [Copyright &y& Elsevier]

A variety of observational and modeling studies show that changes in the Atlantic meridional overturning circulation (AMOC) can induce rapid global-scale climate change. In particular, a substantially weakened AMOC leads to a southward shift of the intertropical convergence zone (ITCZ) in both the Atlantic and the Pacific Oceans. However, the simulated amplitudes of the AMOC-induced tropical climate change differ substantially among different models. In this paper, the sensitivity to cloud feedback of the climate response to a change in the AMOC is studied using a coupled ocean–atmosphere model [the GFDL Coupled Model, version 2.1 (CM2.1)]. Without cloud feedback, the simulated AMOC-induced climate change in this model is weakened substantially. Low-cloud feedback has a strong amplifying impact on the tropical ITCZ shift in this model, whereas the effects of high-cloud feedback are weaker. It is concluded that cloud feedback is an important contributor to the uncertainty in the global response to AMOC changes. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of 40 years of measurements of geographic location (longitude, latitude) and power (wind speed) of tropical storms and typhoons over South-East Asia seas, mainly the South China Sea and the Philippine Sea. The results demonstrate the growing intensity of duration of the most severe events. The analysis includes singular spectrum analysis of wind speed series in the period 1960–2000 to identify two sub-periods of roughly similar behavior. Then, the recorded events and occurrences are classified statistically. The most extreme ones from the 1st and 2nd sub-period are plotted as functions of their geographic co-ordinates to assess the spatial evolution of their location. Next, the escalating power and mostly duration of the most extreme typhoons are examined with extreme probability distributions to quantify the resulting climate change consequences in the studied region. Finally, all results are reiterated in the form of conclusions and suggestions for potential follow-up research. [ABSTRACT FROM AUTHOR]

Abstract: As part of a project comparing the structure and function of four marine ecosystems off Norway and the United States, this paper examines the oceanographic responses to climate forcing, with emphasis on recent changes. The four Northern Hemisphere ecosystems include two in the Pacific Ocean (Bering Sea and Gulf of Alaska) and two in the Atlantic Ocean (Georges Bank/Gulf of Maine and the Barents/Norwegian Seas). Air temperatures, wind forcing and heat fluxes over the four regions are compared as well as ocean hydrography and sea-ice conditions where seasonal sea ice is found. The long-term interannual variability in air temperatures, winds and net heat fluxes show strong similarity between adjacent ecosystems and within subregions of an ecosystem, but no significant correlations between Pacific and Atlantic ecosystems and few across the Atlantic. In spite of the lack of correlation between climate forcing and ocean conditions between most of the ecosystems, recent years have seen record or near record highs in air and sea temperatures in all ecosystems. The apparent causes of the warming differ. In the Atlantic, they appear to be due to advection, while in the Pacific temperatures are more closely linked to air-sea heat exchanges. Advection is also responsible for the observed changes in salinity in the Atlantic ecosystems (generally increasing salinity in the Barents and Norwegian Seas and decreasing in the Gulf of Maine and Georges Bank) while salinity changes in the Gulf of Alaska are largely related to increased local runoff. [Copyright &y& Elsevier]

Several studies show that the El Niño-Southern Oscillation (ENSO) is an important factor in determining interannual rainfall variability in South America. This signal is detected in the region including Northeastern Argentina, Uruguay and part of southern Brazil, in the form of excessive rains and big floods in the regional rivers. To check that this relationship was similar in the past the objectives of this paper were to construct a time series of large floods in the Paraná River region from documentary records, during the sixteenth to eighteenth centuries, and to evaluate the relationship between that historical record of extreme floods, the ENSO documentary evidence (Ortlieb, The Documented Historical Record of El Niño Events in Perú: An Update of the Quinn Record (Ortlieb, sixteenth through nineteenth centuries, Diaz and Markgraf, (eds.), El Niño and the southern oscillation. Multiscale variability and global and regional Impacts. Cambridge University Press, pp. 207-295, 2001; Quinn and Neal, The historical record of El Niño events, Bradley and Jones (eds.), Climate since a.d. 1500, Routledges, pp. 623-648, 1992) and the temperature index of the Pacific Ocean (Mann ME et al., Global temperature patterns in past centuries: an interactive presentation, IGBP pages/world data center for paleoclimatology data contribution series #2000-075. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA, 2000). Considering that the period 1904-2000, where 11 out of 16 floods occurred during El Niño events, it can be concluded that the proportion of years with exceptional flow volume in the Paraná River in years with El Niño events in the seventeenth and eighteenth centuries was relatively lower than that of the twentieth century. The reason for this difference is discussed. [ABSTRACT FROM AUTHOR]

The PICES CCCC (North Pacific Marine Science Organization, Climate Change and Carrying Capacity program) MODEL Task Team achieved a consensus on the structure of a prototype lower trophic level ecosystem model for the North Pacific Ocean, and named it the North Pacific Ecosystem Model for Understanding Regional Oceanography, “NEMURO”. Through an extensive dialog between modelers, plankton biologists and oceanographers, an extensive review was conducted to define NEMURO''s process equations and their parameter values for distinct geographic regions. We present in this paper the formulation, structure and governing equations of NEMURO as well as examples to illustrate its behavior. NEMURO has eleven state variables: nitrate, ammonium, small and large phytoplankton biomass, small, large and predatory zooplankton biomass, particulate and dissolved organic nitrogen, particulate silica, and silicic acid concentration. Several applications reported in this issue of Ecological Modelling have successfully used NEMURO, and an extension that includes fish as an additional state variable. Applications include studies of the biogeochemistry of the North Pacific, and variations of its ecosystem''s lower trophic levels and two target fish species at regional and basin-scale levels, and on time scales from seasonal to interdecadal. [Copyright &y& Elsevier]

In this paper, we report on simulations of ecosystem responses to climate change with two planktonic ecosystem models, both coupled to a one-dimensional mixed-layer model run with annual wind and solar heating from Ocean Station P (50°N, 145°W) in the NE subarctic Pacific. The first ecosystem model is a four-component model previously tested with extensive observations from OSP (Deep-Sea Res. II 46 (1999) 2877). The second ecosystem model is more complex, including phytoplankton partitioned into two size classes, and imposed grazing by mesozooplankton, which varies in time according to long-term observations from OSP. Both models include temperature dependence of physiological rates. Two possible climate change scenarios are considered: (i) increasing ocean temperatures by 2°C (and 5°C) applied only to the ecological component, and (ii) changing the availability of iron to phytoplankton in the subarctic Pacific. Responses of the two models are similar, indicating that they are not primarily model-dependent. In the warming cases, annual behavior and average standing stocks decrease marginally (≤ 10% for T = 2°C, and ≤ 22% for T = 5°C, second model only), ecosystem recycling increases with warming, and losses of organic particles to the ocean interior decrease (∼ 10%) in the simpler model or increase slightly ((10%) in the complex model. Removal of any limitation by iron on phytoplankton growth changes phytoplankon standing stocks by 12% or less, but increases standing stocks of microzooplankton by 150% in the simple model and 225% in the complex model. The loss or export of organic particles to the ocean interior, indicative of the rate at which the ecosystem can sequester carbon, increases ∼20% in the first model and 37% in the second model, all of the increase in the second model via grazing by the mesozooplankton. The winter-to-summer drawdown of surface layer nitrate increases in all the climate change simulations.... [ABSTRACT FROM AUTHOR]

Abstract: Characterising how deep-sea communities change on contemporary time-scales and understanding underlying ecosystem processes has become important under changing climate and the rise in the exploitation of deep-sea resources. However, little is known about these dynamics and processes. Long-term observations from which inter-annual variations can be detected are scarce in the deep sea. This study examines inter-annual changes in density, family richness and evenness, family and functional group rank abundance distributions of infaunal polychaetes at two abyssal stations in the North East Pacific (Station M, 1991 to 2005) and in the North East Atlantic (Porcupine Abyssal Plain, 1991 to 1999). The two long-term data sets were used to investigate not only if polychaete community structure and composition varied at inter-annual scales in terms of diversity and rank abundance distributions but also if any changes were related to previous observations in megafauna and environmental factors at each locality. The polychaete community structure at each locality was analysed using univariate statistics as well as multivariate ordination techniques based on Bray-Curtis similarity of the yearly family density. Sub-surface deposit feeders, such as Paraonidae, dominated the North East Pacific, whereas surface deposit feeders, such as Cirratulidae, dominated the North East Atlantic. Both stations showed inter-annual variations in density, family evenness and rank abundance distributions. The greatest changes occurred in 1998 in both time series when polychaete densities peaked, and switches in the rank abundance of the most abundant families and functional groups took place. Inter-annual variations in the polychaete community were correlated with a limited number of holothurian species changes, but no correlation was found with particulate organic matter flux or climate indices. Ecological and environmental factors behind the family-level changes remain elusive. Overall, changes in the dominance of functional groups imply changes in abyssal ecosystem functioning with potential consequences on carbon cycling at the seabed. [Copyright &y& Elsevier]

Abstract: The water masses of the central and western equatorial Pacific can be divided into two parts: the Western Pacific Warm Pool (WPWP) and the Equatorial Upwelling Region (EUR). The behavior of the WPWP plays a significant role in global climate changes such as the El Niño-Southern Oscillation (ENSO), and it drastically modifies the oceanographic conditions in the area every few years. It is important to evaluate changes in time-series diatom fluxes during both the El Niño and the La Niña events. As a part of the Global Carbon Cycle and Related Mapping based on Satellite Imagery (GCMAPS) Program, time-series sediment trap moorings were deployed and recovered along the Equator at seven stations (Sites MT1–MT7) during five R/V Mirai cruises in the central and western Pacific during January 1999–January 2003. The entire length of this study is divided into two phases depending on the oceanographic conditions: the La Niña event (1999 and 2000); and the El Niño event (2002). Site MT3 was located in the WPWP and Sites MT5–MT7 were in the EUR. Annual means of total diatom fluxes increased towards the east in each year. The fluxes observed at Sites MT4–MT6 decreased from the La Niña event to the El Niño event. However, the fluxes observed at Site MT3 in 2001 and 2002 were higher than those in 2000. Total diatom fluxes showed different seasonal patterns at all sites. The diatom assemblages in the WPWP differed from those of the EUR. Pennate diatoms (e.g., Nitzschia bicapitata, Thalassionema nitzschioides) dominated in the WPWP, while the relative abundances of centric diatoms (e.g., Rhizosolenia bergonii, Azpeitia spp., Thalassiosira spp.) were higher than those of pennate diatoms in the EUR. The diatom fluxes during the La Niña event reflected seasonal oscillation of the WPWP in spatial extent. At Site MT3 during El Niño, terrestrial materials appeared to have been transported by subsurface currents, which might be a secondary influence on total diatom fluxes. The spatial extent of the WPWP reached Site MT7 in 2002, when total diatom fluxes decreased in the sediment traps located in the eastern region including Site MT7. Therefore, we conclude that the relationships between the ENSO and diatoms fluxes in the western and central equatorial Pacific can be explained by the geographic (west–east) expansion or contraction of the WPWP. [Copyright &y& Elsevier]