Eastern Pacific Research Articles

First records of Herald Petrel Pterodroma heraldica on Phillip Island (Norfolk Island Group)

The Herald Petrel Pterodroma heraldica is a medium-sized gadfly petrel that breeds primarily on islands across the tropical and subtropical South Pacific Ocean. Its only confirmed breeding site in the Australasian region is Raine Island off North Queensland, where it occurs in very small numbers. Here we report on the presence of a Herald Petrel ashore on Phillip Island (Norfolk Island Group) in June 2021, and subsequent sightings in May and June 2022. On most occasions that a Herald Petrel was observed on the ground, it was seen under a shrub, behaviour which is consistent with prospecting for a nest site in this surface-nesting species. These sightings make Phillip Island one of just four locations in Australian territory at which the Herald Petrel has been recorded ashore away from Raine Island. Our new records reinforce the importance of active island restoration and the value of long-term intensive monitoring efforts. Future observations will confirm whether the species attempts to establish on Phillip Island, a location free from introduced predators and with ample suitable habitat.

Taxonomy and systematics of shallow-water tropical benthic foraminifera from the lagoon environments at Bora Bora, Society Islands, French Polynesia

Bora Bora is a volcanic island in the tropical central South Pacific Ocean with a barrier reef and large well developed back-reef lagoons. It forms part of the system of shallow water environments in the archipelagos of French Polynesia that provide stepping stones for the interconnectivity of shallow marine faunas between the tropical Western and Eastern Pacific biogeographic regions. The fauna has many similarities to foraminiferal faunas in the south western Indo-Pacific but has been demonstrated to be unique. This study provides illustrations and discussions of most of the 184 species of benthic foraminifera identified from sediments in the back-reef lagoon environments at Bora Bora, that span from the shallow immediate back-reef sand banks, to the deep lagoons and to the coastal fringing reefs and embayments around the volcanic island. The illustrated specimens and taxonomic discussions are aimed at providing an identification guide to shallow water tropical benthic foraminifera from the central South Pacific region. Six new species have been established, including Textularia boraboraensis, Miliolinella mccullochae, Quinqueloculina guilcheri, Triloculina karimimossadeghae, Coscinospira georgforsteri, and Elphidium venecpeyreae. This study also proposes that the family of cymbaloporetids, Cymbaloporidae, are placed within the Superfamily Discorboidea.

Intertidal algae as occasional refuge for insects in Colombian Pacific mangrove forests

A survey of the epiphytic flora associated with mangrove roots was undertaken in Málaga and Buenaventura bays, Colombia, in the tropical eastern Pacific. Roots were collected and preserved in 96% ethanol. In the laboratory, all the epiphytic flora was removed and identified. Three females of Anaphes sp. (Hymenoptera, Mymaridae) were found inside thalli of the red alga Catenella caespitosa (Withering) LM Irvine. The three specimens were fully developed but slightly teneral and still in their host eggs, so they could not be identified to species. This is the first record of any insect developing inside the thallus of a marine alga.

The Heat Budget of the Tropical Pacific Mixed Layer during Two Types of El Niño Based on Reanalysis and Global Climate Model Data

The heat budget of the equatorial Pacific mixed layer during El Niño formation was studied based on reanalysis (GLORYS2V4) and model data for the modern climate. The focus of the study is on the so-called El Niño diversity, i.e., the existence of different types of events that are characterized by different locations and intensities, as well as significantly different teleconnection all around the world. The analysis of the processes that participate in the formation of different El Niño types may serve for a better understanding of the El Niño dynamic and contribute to improving its forecast. Two classifications, based on the location and intensity of the events, were considered: strong/moderate and Eastern Pacific (EP)/Central Pacific (CP). The analysis did not reveal a significant difference in the heat budget of the mixed layer between strong and EP El Niño events, as well as between moderate and CP events. The major difference in the generation mechanism of strong (EP) and moderate (CP) El Niño events consists of the magnitude of heating produced by ocean heat budget components with higher heating rates for strong (EP) events. The evolution of sea surface temperature anomalies (SSTA) is governed primarily by oceanic advection. The vertical advection (due to the thermocline feedback) is the main contributor to SSTA growth in the eastern Pacific regardless of El Niño’s type. In the Central Pacific, horizontal advection is more important than vertical one, with a stronger impact of meridional processes for both strong and moderate regimes. Furthermore, the evaluation of the CMIP5 model’s skill in the simulation of the processes responsible for the formation of different El Niño types was carried out. The analysis of the heat budget of the mixed layer in the CMIP5 ensemble demonstrated that the most successful models are CCSM4, CESM1-BGC, CMCC-CMS, CNRM-CM5, GFDL-ESM2M, and IPSL-CM5B-LR. They are capable of reproducing the most important contribution of the advection terms in the SSTA tendency, keeping the major role of the thermocline feedback (and vertical advection) in the eastern Pacific, and do not overestimate the contribution of zonal advective feedback. These models are recommended to be used for the analysis of El Niño mechanism modification in the future climate.

The 1991–2020 sea surface temperature normals

AbstractThe 1991–2020 climate normals for sea surface temperature (SST) are computed based on the NOAA Daily Optimum Interpolation SST dataset. This is the first time that high‐resolution SST normals with global coverage can be achieved in the satellite SST era. Normals are one of the fundamental parameters in describing and understanding weather and climate and provide decision‐making information to industry, public, and scientific communities. This product suite includes SST mean, standard deviation, count and extreme parameters at daily, monthly, seasonal and annual time scales on 0.25° spatial grids. The main feature of the SST mean state revealed by the normals is that in the Tropics, the Indo‐Pacific Ocean is dominated by the warm pool (SST ≥ 28°C) while the eastern Pacific is characterized by the cold tongue (SST ≤ 24°C); in the midlatitudes, SSTs are in zonal patterns with high meridional gradients. Daily SST standard deviations are generally small (<1.0°C) except in frontal zones (>1.5°C) mostly associated with ocean currents such as the Gulf Stream, Kuroshio and Equatorial Currents. Compared to the 1982–2011 climatology, the 1991–2020 mean SSTs increased over most global areas but obvious cooling is seen in the Southern Ocean, eastern tropical South Pacific Ocean and North Atlantic warming hole. The Indo‐Pacific warm pool (IPWP) is found to have strengthened in both intensity and coverage since 1982–2011. By a count parameter criterion of ≥300 days annually with SST ≥ 28°C, the IPWP coverage increased 33% from 1982–2011 to 1991–2020. The global mean SST of 1991–2020 is warmer than that of 1982–2011, and the warming rate over 1991–2020 doubles that over 1901–2020.

Tropical cyclone activity around Taiwan modulated by El Niño during 1900–1945 and 1970–2015

AbstractTropical cyclone (TC) activity around Taiwan is analysed via typhoon datasets compiled by the Central Weather Administration (CWA) for the pre‐satellite era of 1900–1945 (IE1) and the satellite era of 1970–2015 (IE2). Modulating processes imposed by El Niño years on active and inactive TC activity around Taiwan in the July–September season are examined and compared between IE1 and IE2. Analyses reveal coherent dynamic relationships between TC variability in Taiwan and large‐scale modulating processes; furthermore, modulating processes exhibit similar features between IE1 and IE2. El Niño years tend to have more (less) TC formation in the eastern (western) sector of the western North Pacific (WNP). In both IE1 and IE2, intensified TC activity around Taiwan is associated with northwestward TC tracks from the eastern WNP toward Taiwan assisted by a westward‐elongating cyclonic anomaly across the WNP and South China Sea. When a WNP cyclonic anomaly stretches northwestward toward oceans north of Taiwan, TCs from the tropical eastern WNP generally move northward toward oceans east of Taiwan to result in suppressed TC activity around Taiwan. The westward‐elongating anomalous cyclone is associated with an anomalous divergent centre over the Indian Ocean and an anomalous convergent centre in the tropical eastern Pacific over the 150°–130°W region. The northwestward‐extending anomalous cyclone connects with an anomalous divergent centre over the Maritime Continent and an anomalous convergent centre over the 130°–110°W region. Anomalous divergent and convergent centres displace westward (eastward) for active (inactive) TC types that are related to a more westward (eastward) maximum centre of anomalous warm waters in the tropical eastern Pacific. The above coherent dynamic relationships justify the reliability of TC records compiled by the CWA during IE1 and IE2.

First Observational Perspectives of “Millipede Clouds” Over the Eastern Pacific Ocean

AbstractThe fundamental features of one kind of rarely known stratocumulus, which was termed as “Millipede Cloud,” occurred over the Eastern Pacific Ocean in 2017 were first documented by using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. These clouds had long and meandering “central axes” extending from several hundreds to thousands kilometers, and a number of “radical cloud arms” extending several tens of kilometers in its two sides. Total 59 “Millipede Clouds,” 4 and 55 of them, were formed over the Northern and the Southern Hemispheres, respectively. Their environmental backgrounds were analyzed by using ERA5 reanalysis data and MODIS sensor Level‐2 data. The cloud top pressures of these “Millipede Clouds” were between 850 and 800 hPa, and their top heights were about 1–2 km. There existed “inversion layer” of air temperature near the cloud tops at 800 hPa, which strongly suggested that these clouds were lower stratocumulus in essence.

Wettening of the Southern Hemisphere Land Monsoon during 1901–2014

Abstract The causes of historical changes in the Southern Hemisphere (SH) monsoon are less understood than the Northern Hemisphere (NH) counterpart. Unlike the decline in the NH monsoon during 1901–2014, we found that the SH land monsoon precipitation significantly increased during 1901–2014 in observation, reanalysis, and most historical simulations from phase 6 of the Coupled Model Intercomparison Project (CMIP6). The observed increase in SH land monsoon precipitation is dominated by the Australian and South American monsoons. Moisture budget analysis suggests that half of the wettening is attributable to the strengthening of monsoon circulation, and only one-fifth is caused by atmospheric moistening. The SH monsoon circulation change is mainly affected by the sea surface temperature (SST) gradient between the Indo-Pacific and the eastern Pacific. It enhances the tropical zonal circulation that redistributes the moisture from tropical oceans to land monsoon regions by strengthening the lower-tropospheric convergence and convection. The CMIP6 models, which successfully reproduced the SST contrast between the Indo-Pacific and eastern Pacific, simulate the wettening of the SH monsoon during the historical period; otherwise, the SH monsoon is weakened. In a meridional sense, reanalysis and CMIP6 simulations both demonstrated that the strengthening of SH monsoon convection plays a vital role in the long-term change of zonal mean Hadley circulation, albeit the monsoon band only accounts for 1/3 of the global longitudinal area. Results from this study are useful for constraining the future projection of SH monsoon and understanding the long-term change of Hadley circulation.

An Extratropical Pathway for the Madden–Julian Oscillation’s Influence on North Atlantic Tropical Cyclones

Abstract This study investigates the combined impacts of the Madden–Julian oscillation (MJO) and extratropical anticyclonic Rossby wave breaking (AWB) on subseasonal Atlantic tropical cyclone (TC) activity and their physical connections. Our results show that during MJO phases 2–3 (enhanced Indian Ocean convection) and 6–7 (enhanced tropical Pacific convection), there are significant changes in basinwide TC activity. The MJO and AWB collaborate to suppress basinwide TC activity during phases 6–7 but not during phases 2–3. During phases 6–7, when AWB occurs, various TC metrics including hurricanes, accumulated cyclone energy, and rapid intensification probability decrease by ∼50%–80%. Simultaneously, large-scale environmental variables, like vertical wind shear, precipitable water, and sea surface temperatures become extremely unfavorable for TC formation and intensification, compared to periods characterized by suppressed AWB activity during the same MJO phases. Further investigation reveals that AWB events during phases 6–7 occur in concert with the development of a stronger anticyclone in the lower troposphere, which transports more dry, stable extratropical air equatorward, and drives enhanced tropical SST cooling. As a result, individual AWB events in phases 6–7 can disturb the development of surrounding TCs to a greater extent than their phases 2–3 counterparts. The influence of the MJO on AWB over the western subtropical Atlantic can be attributed to the modulation of the convectively forced Rossby wave source over the tropical eastern Pacific. A significant number of Rossby waves initiating from this region during phases 5–6 propagate into the subtropical North Atlantic, preceding the occurrence of AWB events in phases 6–7.

The Indian Ocean Weakens the ENSO Spring Predictability Barrier: Role of the Indian Ocean Basin and Dipole Modes

Abstract Prediction of El Niño–Southern Oscillation (ENSO) is hindered by a spring predictability barrier (SPB). In this paper, we investigate the effects of the Indian Ocean (IO) on the SPB. Using a seasonally varying extended IO–ENSO recharge oscillator model, we find that the SPB is much weakened when IO is coupled with ENSO. To gauge the relative role of the Indian Ocean dipole (IOD) and the Indian Ocean Basin (IOB) modes in weakening ENSO SPB, we develop an empirical dynamical model, the linear inverse model (LIM). By coupling/decoupling the IOB or IOD mode with ENSO, we show that the IOB significantly weakens eastern Pacific and central Pacific ENSO SPBs, while the IOD plays a weaker role. The evolution of the optimum initial structures also illustrates the importance of the IOB in ENSO SPB. Moreover, the IOB strongly influences the forecast skill of La Niña SPB rather than El Niño SPB. This point is also identified through six coupled models from the North American multimodel ensemble. It may be related to the role of the IO in the asymmetry in the duration of El Niño and La Niña. The IOB-induced easterly wind anomalies are conducive to the development of La Niña and thus the prediction of La Niña events, whereas these anomalous easterlies are less important during the development of El Niño and the related forecast of El Niño events.

Algal cover as a driver of diversity in communities associated with mussel assemblages across eastern Pacific ecoregions

AbstractResearch on intertidal mussel assemblages and associated communities has revealed that complexity and structure are influenced by environmental heterogeneity and local‐scale factors affecting recruitment. Research in situ in eastern and western Pacific intertidal ecosystems has suggested drivers of species diversity and community structure encompassing large geographic scales, however, there are major gaps in geographic coverage. Our aim is to fill some of these gaps by analyzing macrofaunal functional group diversity and effects of environmental factors on intertidal mussel communities from three distinct marine ecoregions in the southern and northern hemispheres. We identified the effects of algal cover and environmental heterogeneity on species richness and evenness, and we modeled factors effecting mussel layer complexity from assemblages in three marine ecoregions. We analyzed macrofaunal species diversity within one of the austral ecoregions based on the width of the coastal shelf. Species richness was highest in samples from the northern hemisphere while evenness was highest in samples from the southern hemisphere. Similarity in functional group structure for all communities sampled was ≤55% (Bray–Curtis dissimilarity) and ≤35% (Chao–Jaccard dissimilarity). Wave exposure had a significant effect on shell length and complexity of mussel matrices on rocky bench platforms. The presence of algal cover had a strong effect on species richness in mussel matrices regardless of complexity, while algal canopies had no effect on species evenness. Overall, this study provides significant new insight on the community complexity of mussel beds in parts of the world which have been poorly studied in this regard.

Climate intervention using marine cloud brightening (MCB) compared with stratospheric aerosol injection (SAI) in the UKESM1 climate model

Abstract. The difficulties in using conventional mitigation techniques to maintain global-mean temperatures well below 2 ∘C compared with pre-industrial levels have been well documented, leading to so-called “climate intervention” or “geoengineering” research whereby the planetary albedo is increased to counterbalance global warming and ameliorate some impacts of climate change. In the scientific literature, the most prominent climate intervention proposal is that of stratospheric aerosol injection (SAI), although proposals for marine cloud brightening (MCB) have also received considerable attention. In this study, we design a new MCB experiment (G6MCB) for the UKESM1 Earth-system model which follows the same baseline and cooling scenarios as the well-documented G6sulfur SAI scenario developed by the Geoengineering Model Intercomparison Project (GeoMIP), and we compare the results from G6MCB with those from G6sulfur. The deployment strategy used in G6MCB injects sea-salt aerosol into four cloudy areas of the eastern Pacific. This deployment strategy appears capable of delivering a radiative forcing of up to −1 W m−2 from MCB, but at higher injection rates, much of the radiative effect in G6MCB is found to derive from the direct interaction of the injected sea-salt aerosols with solar radiation, i.e. marine sky brightening (MSB). The results show that while G6MCB can achieve its target in terms of reducing high-end global warming to moderate levels, there are several side effects. Some are common to SAI, including overcooling of the tropics and residual warming of middle and high latitudes. Other side effects specific to the choice of the targeted MCB regions include changes in monsoon precipitation, year-round increases in precipitation over Australia and the maritime continent, and increased sea-level rise around western Australia and the maritime continent; these results are all consistent with a permanent and very strong La Niña-like response being induced in G6MCB. The results emphasize that considerable attention needs to be given to oceanic feedbacks for spatially inhomogeneous MCB radiative forcings. It should be stressed that the results are extremely dependent upon the strategy chosen for MCB deployment. As demonstrated by the development of SAI strategies which can achieve multiple temperature targets and ameliorate some of the residual impacts of climate change, much further work is required in multiple models to obtain a robust understanding of the practical scope, limitations, and pitfalls of any proposed MCB deployment.

SUPERDOVE-MODELLED BATHYMETRY USING NEURAL NETWORKS ALONG A TURBIDITY GRADIENT: BREHAT, SAINT-BARTHELEMY AND TETIAROA ISLANDS

Abstract. Despite the increasing interest in the bathymetry mapping in the context of the sea level rise and storm intensification, only 10% of the worldwide bathymetry has been mapped with reliable sonar and lidar, due to their high cost. The satellite-derived bathymetry (SDB) has therefore grown for the last decades, due to its affordability, but also to its gain in radiometric, spatial, spectral and temporal resolutions. Nevertheless, SDB products leveraging both a high spatial and a high temporal resolution are still expected by stakeholders responsible for cloudy or tidal coastal areas. This research tests the contribution of the Planetscope SuperDove CubSats (eight-band, 3 m, 1 day) four novel bands in bathymetry extraction, along a turbidity gradient (the islands of Bréhat in Channel Sea, Saint-Barthélémy in Caribbean Atlantic Ocean, and Teti’aroa in South Pacific Ocean), using neural networks calibrated, validated, and tested with recent topobathymetric lidar data. In Bréhat (turbid) and Saint-Barthélémy (clear), water depth was best modelled using the eight-band dataset with good contributions of yellow and green 1 for Bréhat (R2=0,77), and purple and green 1 for Saint-Barthélémy (R2=0,95). The very clear waters of Teti’aroa were best modelled using the combination of base (blue, green 2, red and near-infrared) + yellow (R2=0,68). The lower accuracy of bathymetry mapping in Teti’aroa revealed biases due to satellite-lidar collection time difference, lidar data specificities, and/or control quality.

Different influences of La Niña types on the winter sub-seasonal Eurasian cold anomalies linked to Ural blocking

The effects of different types of La Niña on winter sub-seasonal cold anomalies or cold extremes over Eurasia and Siberia are examined through exploring changes in Ural blocking (UB). It is found that the Central Pacific (CP) La Niña can significantly influence surface air temperature over Eurasia mainly by regulating the movement, persistence, zonal scale and location of the cyclonic anomaly associated with the UB. This influence is much greater than that resulting from an Eastern Pacific (EP) La Niña. A long-lived and quasi-stationary cyclonic anomaly with a large zonal scale of UB is induced to the southeast of the Ural Mountains for CP-type La Niña conditions, which leads to a strong warm Arctic-cold Eurasia pattern with an intense sub-seasonal cold anomaly or cold event in the broad region of Eurasia due to strongly reduced downward infrared radiation over Eurasia. In contrast, for EP-type La Niña winter the cyclonic anomaly, while still present, is much weaker, short-lived and eastward propagating, resulting in only a very weak cold anomaly or cold event over a small region of Eurasia. The reduced (enhanced) eastward movement and increased (decreased) persistence of the cyclonic anomaly with large (small) zonal scale of UB are shown to be associated with reduced (enhanced) meridional potential vorticity gradient in the midlatitudes (30o-50oN) to the east of 60°E during the CP-type (EP-type) La Niña winter.

Microbial shifts associated to ENSO-derived thermal anomalies reveal coral acclimation at holobiont level

The coral microbiome conforms a proxy to study effects of changing environmental conditions. However, scarce information exists regarding microbiome dynamics and host acclimation in response to environmental changes associated to global-scale disturbances. We assessed El Niño Southern Oscillation (ENSO)-derived thermal anomalies shifts in the bacterial microbiome of Pacifigorgia cairnsi (Gorgoniidae: Octocorallia) from the remote island of Malpelo in the Tropical Eastern Pacific. Malpelo is a hot spot of biodiversity and lacks direct coastal anthropogenic impacts. We evaluated the community composition and predicted functional profiles of the microbiome during 2015, 2017 and 2018, including different phases of ENSO cycle. The bacterial community diversity and composition between the warming and cooling phase were similar, but differed from the neutral phase. Relative abundances of different microbiome core members such as Endozoicomonas and Mycoplasma mainly drove these differences. An acclimated coral holobiont is suggested not just to warm but also to cold stress by embracing similar microbiome shifts and functional redundancy that allow maintaining coral’s viability under thermal stress. Responses of the microbiome of unperturbed sea fans such as P. cairnsi in Malpelo could be acting as an extended phenotype facilitating the acclimation at the holobiont level.

Evolution of ENSO‐related seasonal precipitation anomalies in East Asia: A robustness revisit

AbstractThe El Niño–Southern Oscillation (ENSO) is a major source of seasonal climate predictability and a key predictor for East Asian precipitation. However, the impacts of ENSO on East Asian precipitation are extremely complex and still controversial. Thus, it is necessary and significant to use various (observational and model) data sources to further examine the robustness of the impacts. This study revisits the evolution of the ENSO‐related seasonal precipitation anomalies in East Asia, including symmetric and asymmetric impacts of El Niños and La Niñas, the differences in the influences of eastern Pacific (EP) and central Pacific (CP) El Niños, and the interdecadal change of ENSO influences. The ENSO impact on East Asian precipitation has weakened (strengthened) in the ENSO's developing (decay) phase in the recent two decades. The ENSO impacts are robust in (i) southern China‐lower reaches of the Yangtze River‐southern Japan around the ENSO's mature phase, (ii) western North China in the developing phase and (iii) southwestern China in the decay phase. The distribution of East Asian precipitation anomalies is asymmetric in El Niño and La Niña years. The model simulations forced with observed sea surface temperature generally reproduce the observed evolution of seasonal precipitation anomalies associated with ENSO and confirm the robust impact of ENSO in East Asia. These results indicate the necessity to consider the asymmetric impact of El Niños and La Niñas, to distinguish the El Niño flavours for their impact on the East Asian climate, and to include the interdecadal variation of ENSO influence in addressing East Asian climate anomalies.

Anthropogenic noise predicts sea turtle behavioural responses

Anthropogenic noise is a pollutant of global concern. While the effects of underwater noise pollution have been frequently studied in fish and mammals, our understanding of how this anthropogenic stressor affects marine reptiles is scant. Using a multichannel data logger equipped with a camera and hydrophone, we quantified behavioural responses of a free-ranging green turtle (Chelonia mydas) to vessel noise in the Galapagos Archipelago, an important nesting site in the eastern Pacific. We found that while travelling the turtle increased its vigilance with increasing vessel noise. However, when on the seabed the turtle did not increase its vigilance with increasing noise levels. Our findings illustrate that noise pollution has the potential to alter overall time budgets of animals. Identifying real-time responses of wild animals illustrate how in situ approaches allow to assess the effects of human activities on marine systems.

Towards a refined Norian (Upper Triassic) conodont biostratigraphy of the western Tethys: revision of the recurrent ‘multidentata-issue’

AbstractThe issue of oversimplified Norian conodont taxonomy has set back the development of Norian conodont biostratigraphy of the western Tethys Realm for decades. The majority of stratigraphic studies used the name Epigondolella multidentata, a North American endemic, to gather specimens indicative of strata from the lower part of the middle Norian substage. Detailed conodont biostratigraphic investigations were carried out on the Norian hemipelagic cherty dolostones of the Mátyás Hill section in the Buda Hills (Hungary) in order to resolve the ‘multidentata problem’. The age of the section ranges from the upper part of the lower Norian substage (Lacian-3) to the lower part of the middle Norian substage (Alaunian-1). The new species Ancyrogondolella manueli n. sp. is introduced, and A. transformis is documented for the first time in the Tethys. The studied conodont fauna significantly improves the correlation potential between the western Tethys and the eastern Pacific.

Contrasting drivers of abundant phage and prokaryotic communities revealed in diverse coastal ecosystems

Phages (viruses of bacteria and archaea) are a ubiquitous top-down control on microbial communities by selectively infecting and killing cells. As obligate parasites, phages are inherently linked to processes that impact their hosts’ distribution and physiology, but phages can also be impacted by external, environmental factors, such as UV radiation degrading their virions. To better understand these complex links of phages to their hosts and the environment, we leverage the unique ecological context of the Isthmus of Panama, which narrowly disconnects the productive Tropical Eastern Pacific (EP) and nutrient-poor Tropical Western Atlantic (WA) provinces. We could thus compare patterns of phage and prokaryotic communities at both global scales (between oceans) and local-scales (between habitats within an ocean). Although both phage and prokaryotic communities differed sharply between the oceans, phage community composition did not significantly differ between mangroves and reefs of the WA, while prokaryotic communities were distinct. These results suggest phages are more shaped by dispersal processes than local conditions regardless of spatial scale, while prokaryotes tend to be shaped by local conditions at smaller spatial scales. Collectively, we provide a framework for addressing the co-variability between phages and prokaryotes in marine systems and identifying factors that drive consistent versus disparate trends in community shifts, essential to informing models of biogeochemical cycles that include these interactions.

Quantifying the Environmental Effects on Tropical Cyclone Intensity Change Using a Simple Dynamically Based Dynamical System Model

Abstract Accurate prediction of tropical cyclone (TC) intensity is quite challenging due to multiple competing processes among the TC internal dynamics and the environment. Most previous studies have evaluated the environmental effects on TC intensity change from both internal dynamics and external influence. This study quantifies the environmental effects on TC intensity change using a simple dynamically based dynamical system (DBDS) model recently developed. In this simple model, the environmental effects are uniquely represented by a ventilation parameter B, which can be expressed as multiplicative of individual ventilation parameters of the corresponding environmental effects. Their individual ventilation parameters imply their relative importance to the bulk environmental ventilation effect and thus to the TC intensity change. Six environmental factors known to affect TC intensity change are evaluated in the DBDS model using machine learning approaches with the best track data for TCs over the North Atlantic, central, eastern, and western North Pacific and the Statistical Hurricane Intensity Prediction Scheme (SHIPS) dataset during 1982–2021. Results show that the deep-layer vertical wind shear (VWS) is the dominant ventilation factor to reduce the intrinsic TC intensification rate or to drive the TC weakening, with its ventilation parameter ranging between 0.5 and 0.8 when environmental VWS between 200 and 850 hPa is larger than 8 m s−1. Other environmental factors are generally secondary, with their respective ventilation parameters over 0.8. An interesting result is the strong dependence of the environmental effects on the stage of TC development.