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In this study, we evaluate the intensity of the Central‐Pacific (CP) and Eastern‐Pacific (EP) types of El Niño‐Southern Oscillation (ENSO) simulated in the pre‐industrial, historical, and the Representative Concentration Pathways (RCP) 4.5 experiments of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Compared to the CMIP3 models, the pre‐industrial simulations of the CMIP5 models are found to (1) better simulate the observed spatial patterns of the two types of ENSO and (2) have a significantly smaller inter‐model diversity in ENSO intensities. The decrease in the CMIP5 model discrepancies is particularly obvious in the simulation of the EP ENSO intensity, although it is still more difficult for the models to reproduce the observed EP ENSO intensity than the observed CP ENSO intensity. Ensemble means of the CMIP5 models indicate that the intensity of the CP ENSO increases steadily from the pre‐industrial to the historical and the RCP4.5 simulations, but the intensity of the EP ENSO increases from the pre‐industrial to the historical simulations and then decreases in the RCP4.5 projections. The CP‐to‐EP ENSO intensity ratio, as a result, is almost the same in the pre‐industrial and historical simulations but increases in the RCP4.5 simulation. Key Points Smaller inter‐model diversity of ENSO intensities in CMIP5 than in CMIP3 Decrease in the diversity is particularly significant for the simulated EP ENSO Different response of EP and CP ENSO to global warming

Much understanding of the El Niño‐Southern Oscillation (ENSO) has been obtained from the analyses of the climate simulations produced for World Climate Research Programme's Coupled Model Intercomparison Project phase 3 (CMIP3). However, most of these analyses do not consider the existence of the Eastern‐Pacific (EP) and Central‐Pacific (CP) types of ENSO events, which have been increasingly recognized as two distinct types of interannual sea surface temperature (SST) variation in the tropical Pacific. This study uses a regression‐Empirical Orthogonal Function method to identify how well these two ENSO types are captured in the pre‐industrial simulations of nineteen CMIP3 models. It is concluded that most CMIP3 models (13 out of 19) can produce realistically strong CP ENSOs, but only a few of them (9 out of 19) can produce realistically strong EP ENSOs. Six models that realistically simulate both the EP and CP ENSOs and their intensity ratio are identified. By separating the SST variability into these two types, it is further revealed that the leading periodicity of the simulated EP ENSO is linearly related to the latitudinal width of SST variability and varies from 1 to 5 years. As for the simulated CP ENSO, its leading periodicity is either 2 or 4 years depending on whether its SST variability is located to the east of the dateline or in the western‐Pacific warm pool, respectively. The identification produced in this study offers useful information to further understand the two types of ENSO using the CMIP3 models.

Aim: The distribution and genetic composition of marine populations is the result of climatic and oceanographic factors as well as life history strategies. Studying species with wide distributions and high dispersal potential in sites that were differentially affected during the Pleistocene glaciations provides an opportunity to evaluate the genetic and distributional effect of glaciations on marine populations, such as the limpet Siphonaria lesonii. The aim of the present study is to evaluate the differential effects of glaciations on areas covered and not covered by ice sheets during the Pleistocene glaciations. Location: Intertidal zone of the south-eastern Pacific covering approximately 5,000 km of coastline of Peru and Chile. Methods: We performed molecular analyses of mitochondrial and nuclear data jointly, as well as environmental niche modelling (ENM) of populations of the limpet Siphonaria lessonii. Using ENM, we modelled the potential distributional range of the species in the present and its distribution during the Last Glacial Maximum (LGM). Results: Two lineages were found that were separated by a break at 41° S, corresponding to the biogeographical discontinuity previously reported for this region. Both of these lineages experienced genetic and demographical fluctuations that match the Pleistocene glaciations; however, the variability was more intense in the southern lineage. Phylogeography and ENM yielded complementary results for the southern lineage, which experienced loss of genetic diversity and habitat during the LGM, whereas the northern lineage evidenced loss of genetic diversity without distributional changes. Main conclusions: The phylogeographical and ENM approaches suggest a historical scenario involving demographic and distributional contractions of S. lessonii surviving in glacial refugia in the southern portion of the south-eastern Pacific. This study is the first to include both phylogeographical and ENM analyses of marine species from the Southern Hemisphere.

The purpose of this study was to test the hypothesis that the genetic diversity of commercially significant species of King Crabs (Lithodes spp.) along the south‐eastern Pacific (SEP) comprises different independent evolutionary units (IEUs) with spatially isolated distribution. Nine localities from inner and open waters along the SEP Chilean coast (39°S‐55°S) were sampled. We analyzed sequences from 173 individuals for the mitochondrial gene Cytochrome oxidase I (COX‐I), 151 individuals for the Internal Transcribed Spacer 1 (ITS) and 135 for the structural ribosomal RNA (28S). Genetic delimitation was performed through three analytical methods: ABGD, GMYC, and its Bayesian implementation, bGMYC. Bayesian phylogenetic analyses and haplotype networks were also performed. Divergence time between clades was assessed for the COX‐I marker and estimated from known evolutionary rates for this marker in other crustacean species and fossil calibration from other Anomuran species. Delimitation analyses, phylogenetic analyses, and mitochondrial haplotype networks suggested the presence of two deeply divergent mitochondrial lineages of Lithodes in the SEP, referred to as Clade1 and Clade 2. Nuclear markers showed low phylogenetic resolution and therefore were unsuitable for molecular species delimitation. Divergence time analysis of the mitochondrial lineages suggests a separation between Clades of approximately 2.3 Mya. The divergence time obtained suggested that Pliocene glaciations and deglaciations cycles could be involved in hybridization events between Lithodes IEUs at southern tip of South American coasts. The different frequencies of Lithodes haplotypes in inner and open water environments along SEP coasts could be explained by events such as the last glacial maximum or by differences in the adaptation of each clade to different environments. These findings support the necessity of evaluating the taxonomic status of Lithodes individuals found along SEP coasts under an integrative taxonomy approach or through markers with other evolution rates than those already used. The purpose of this study was to assess the biodiversity of individual Lithodes spp. across the Southerneast Pacific with multilocus molecular markers. A complex of independent evolutionary units comprising at least two genetically distinct lineages with different spatial distribution is observed.

The present study investigates inter‐annual variations of precipitation during transitional periods (August–September) of the rainy season over the monsoon transitional zone (MTZ) in China. More precipitation tends to occur over the MTZ during August–September when a significant anticyclonic anomaly simultaneously appears over the western North Pacific (WNP). Prominent southerly wind anomalies induced by the anticyclonic anomaly over the WNP contribute to more precipitation over the MTZ via transporting abundant water vapor northward. Sea surface temperature (SST) cooling in the tropical central‐eastern Pacific and SST warming in the northern tropical Atlantic (NTA) are crucial to the formation of the anticyclonic anomaly over the WNP. In addition, it is showed that the significant impact of the SST warming in the NTA on the WNP anticyclonic anomaly is independent of the SST cooling in the tropical central‐eastern Pacific. Atmospheric general circulation model experiments demonstrate that the SST warming over the NTA can produce an anticyclonic anomaly over the WNP via modulation of the Walker circulation with upward motion anomalies over the NTA and downward motion anomalies over the tropical central Pacific. The resultant negative precipitation anomalies over the tropical central Pacific further trigger an anticyclonic anomaly over the WNP via a Gill‐type atmospheric response. The results suggest that SST anomalies in the tropical central‐eastern Pacific and the NTA play a key driver for inter‐annual variations of precipitation over the MTZ in China during August–September. More precipitation tends to occur over the MTZ during August–September when a significant anticyclonic anomaly simultaneously appears over the western North Pacific (WNP). Prominent southerly wind anomalies induced by the anticyclonic anomaly over the WNP contribute to more precipitation over the MTZ via transporting abundant water vapour northward. Sea surface temperature (SST) cooling in the tropical central‐eastern Pacific and SST warming in the northern tropical Atlantic (NTA) are crucial to the formation of the anticyclonic anomaly over the WNP. In the figure, (a) SST (unit: °C), and (b) 500 hPa omega (unit: 10−3 Pa/s) anomalies during August–September obtained by regression upon the simultaneous August–September MTZI. Values of 500 hPa omega over the land in (b) are omitted. Stippling regions in (a, b) indicate SST and omega anomalies significant at the 95% confidence level, respectively. Positive (negative) value of omega indicates downward (upward) motion anomalies. (c) Correlation coefficients of the August–September MTZI with the 2‐monthly mean Niño3.4 index (blue solid line), NTA SST index (red solid line), and NTA_res SST index (red dashed line) from preceding February–March to following October–November. Definitions of the Niño3.4 index, NTA SST index, and NTA_res SST index are provided in the main text. Horizontal dashed lines in (c) indicate correlation coefficients significant at the 95% confidence level.

The Pacific interior subtropical−tropical cells (STCs) and their relation to the two types of El Niño-Southern Oscillation (ENSO) are investigated by using GODAS reanalysis ocean data for the period of 1980–2017. The results show that the interior STC transport into the equatorial region across 9°S and 9°N has a close relationship with the eastern Pacific (EP) ENSO, while it is much weaker with the central Pacific (CP) ENSO. It is suggested that the effect of interior STCs on the tropical Pacific climate is reflected in its relation with the western Pacific thermocline depth or SSHA. During the EP El Niño, the anomalous interior STCs at 9°S and 9°N converge to the equatorial region from the lag months of − 25 to − 8, leading to an accumulation of heat content in the equatorial Pacific; from the lag months of − 8 to 10, they diverge poleward, inducing a discharge of equatorial heat content. The peak poleward interior STC anomaly first appears at 9°N at a zero-lag time, while that at 9°S is observed 4–5 months later. But there is also no appearance of a time lag between the interior STCs at 9°N and 9°S in recharging the period during the EP La Niña mature phase. However, during CP El Niño, only the conspicuous anomalous interior STC divergence appears during the mature and decay phases for the lag months of − 2 to 10, with being symmetric at 9°N and 9°S.

The present-day population structure of a species reflects the influence of population history as well as contemporary processes. Little is known about the mechanisms that have shaped the geographical distribution of genetic diversity in marine species present on the south-eastern Pacific (SEP) coast. Here we provide the first comprehensive phylogeographical study of a species distributed along the SEP coast by analysing the endemic and emblematic muricid gastropod Concholepas concholepas. The study localities were distributed along the SEP coast ranging from Matarani (11° S) to Puerto Eden (49° S), crossing three major biogeographical provinces: Peruvian Province, Intermediate Area and Magellanic Province. A total of 337 specimens of C. concholepas were collected from 14 localities in the three biogeographical provinces/areas. Mitochondrial cytochrome oxidase I (COI) gene partial sequences (658 bp) were obtained and analysed using coalescence-based methods to infer molecular diversity and phylogeographical patterns. Across the 337 individuals, we found a large diversity, with a total of 179 haplotypes at the COI gene fragment. Although a slight decrease in gene diversity was observed from north to south, an analysis of molecular variance did not reveal any significant spatial population differentiation from Peru to the tip of Chile, not even across the recognized biogeographical boundaries at 30° S and 42° S. In addition, a star-like haplotype network suggested the past occurrence of a rapid demographic and geographical expansion over the total range examined. Calculations of the onset of this expansion suggest that it might be due to climatic conditions during the period of the marine isotope stage 11 (MIS 11, 400,000 years ago), the longer and warmer interglacial episode during the Pleistocene epoch. Our phylogeographical analyses indicate that in the recent past C. concholepas mitochondrial DNA lineages underwent a sudden population expansion event. In addition, our data do not support the hypothesis of concordance between biogeographical barriers and phylogeographical breaks along the SEP coast. These two results are in accordance with the paradigm of high larval dispersal ability in marine species with an extended pelagic larval phase.

Sea surface salinity (SSS) observations from NASA’s satellite missions, Aquarius/SAC-D and Soil Moisture Active Passive (SMAP), are used to describe spatial patterns of the seasonal cycle, as well as intraseasonal and interannual variability, in the eastern tropical Pacific, the location of the second Salinity Processes in the Upper-ocean Regional Study (SPURS-2) field experiment. The results indicate that the distribution of SSS variance is highly inhomogeneous in both space and time. The seasonal signal is largest in the core of the Eastern Pacific Fresh Pool and in the Gulf of Panama. The interannual signal is highest in a relatively narrow zonal band along approximately 5°N, while the intraseasonal signal appears to be a dominant mode of variability in the zonally stretched near-equatorial region. Located right in the middle of a hotspot of high SSS variance, the SPURS-2 site appears to be at the crossroads of many different processes that shape the distribution of SSS in the eastern tropical Pacific and beyond.

We present the first comprehensive review of the present and past shark and ray diversity in marine waters of Tropical America, examining the patterns of distribution in the Eastern Central Pacific (EP) and Western Central Atlantic (WA) realms. We identified the major regions of diversity and of endemism, and explored the relations to physical variables. We found a strong relationship between shark and ray diversity with area and coastal length of each province. The Tropical Northwestern Atlantic Province is characterized by high diversity and greater occurrence of endemic species, suggesting this province as the hotspot of sharks and rays in Tropical America. The historical background for the current biogeography is explored and analyzed. Referential data from 67 geological units in 17 countries, from both shallow and deep-water habitats, across five time-clusters from the Miocene to the Pleistocene were studied. New data include 20 new assemblages from six countries. The most diverse Neogene and extant groups of shark and ray are Carcharhiniformes and Myliobatiformes, respectively. The differentiation between Pacific and Atlantic faunas goes to at least the middle Miocene, probably related with the increasing closure of the Central American Seaway acting as a barrier. The highest faunal similarity between the assemblages from the EP and the WA at the early Miocene could be related to the lack of a barrier back then, but increased sampling is needed to substantiate this hypothesis.

Nitrous oxide (N 2 O) is a potent greenhouse gas and ozone depleting substance, with the ocean accounting for about one third of global emissions. In marine environments, a significant amount of N 2 O is produced by biological processes in Oxygen Deficient Zones (ODZs). While recent technological advances are making surface N 2 O concentration more available, high temporal and spatial resolution water-column N 2 O concentration data are relatively scarce, limiting global N 2 O ocean models’ predictive capability. We present a N 2 O concentration, stable isotopic composition and isotopomer dataset of unprecedently large spatial coverage and depth resolution in the broader Pacific, crossing both the eastern tropical South and North Pacific Ocean ODZs collected as part of the GO-SHIP P18 repeat hydrography program in 2016/2017. We complement these data with dissolved gases (nitrogen, oxygen, argon) and nitrate isotope data to investigate the pathways controlling N 2 O production in relation to apparent oxygen utilization and fixed nitrogen loss. N 2 O yield significantly increased under low oxygen conditions near the ODZs. Keeling plot analysis revealed different N 2 O sources above the ODZs under different oxygen regimes. Our stable isotopic data and relationships between the N 2 O added by microbial processes (ΔN 2 O) and dissolved inorganic nitrogen (DIN) deficit confirm increased N 2 O production by denitrification under low oxygen conditions near the oxycline where the largest N 2 O accumulations were observed. The slope for δ 18 O-N 2 O versus site preference (SP, the difference between the central (α) and outer (β) N atoms in the linear N 2 O molecule) in the eastern tropical North Pacific ODZ was lower than expected for pure N 2 O reduction, likely because of the observed decrease in δ 15 N β . This trend is consistent with prior ODZ studies and attributed to concurrent production of N 2 O from nitrite with a low δ 15 N or denitrification with a SP >0‰. We estimated apparent isotope effects for N 2 O consumption in the ETNP ODZ of 3.6‰ for 15 N bulk , 9.4‰ for 15 N α , -2.3‰ for 15 N β , 12.0‰ for 18 O, and 11.7‰ for SP. These values were generally within ranges previously reported for previous laboratory and field experiments.