Low Sea Surface Temperature Research Articles

Influence of SST‐Precipitation Relationship Over the Equatorial Western Pacific on Simulation of the Madden‐Julian Oscillation

AbstractCapabilities of 43 models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to simulate the Madden‐Julian Oscillation (MJO) were compared in this study. Models with higher MJO simulation skills reproduce organized large‐scale convection more frequently over the equatorial western Pacific (EWP), suggesting that MJO simulations are tightly connected to organization of large‐scale precipitation over the EWP. MJO simulation skills are not significantly correlated with the mean sea surface temperature (SST) over the EWP, but tightly connected to SST threshold for convection there. The top simulations exhibit lower SST threshold and more realistic SST‐precipitation relationship over the EWP, suggesting that convection can be organized more efficiently and intensified more rapidly with the increasing SST in these simulations. Our results emphasize that reproducing the relationship between SST and large‐scale precipitation over the EWP is critical to MJO simulations.

Response of Upwelling Parameter Before, During, and After Tropical Cyclone (Case Study: Tropical Cyclone Marcus)

Tropical cyclones (TC) can cause damage when they are on the land surface, but on the other hand TC contribute to ocean productivity through upwelling or downwelling when they pass through the ocean. Information of the location and timing of upwelling and downwelling is important for fishing - activities estimation. High chlorophyll-a concentrations and low sea surface temperatures are proxies for upwelling events in the ocean. This study aims to investigate the effects of the TC Marcus on the chlorophyll-a distribution in the Timor Sea using a combination of remotely sensed data from Aqua MODIS chlorophyll-a and ocean-atmosphere reanalysis outputs. The results showed that wind speed, sea surface temperature, salinity, and ocean currents were increased during the TC Marcus event. Spatial analysis reveals that the concentration of chlorophyll-a is high in the waters of the Timor Sea, at coordinates around 12°–13° S and 125°–129° E. High chlorophyll-a concentrations occurred before and after TC Marcus event, according to temporal analysis. The distribution of chlorophyll-a concentrations decreased on March 17–24, 2018, during the occurrence of the TC Marcus in the Timor Sea.

Late Holocene record of subantarctic glacier variability in Table Fjord, Cook Ice Cap, Kerguelen Islands

The subantarctic islands between 40 and 60°S are circum-polar landmasses influenced by the southern westerly wind (SWW) belt whose latitudinal shifts are driven by the Southern Annular Mode (SAM) over decadal timescales. In the Indian sector of the Southern Ocean, the Kerguelen Islands (49°S) form a volcanic archipelago that is home to the Cook Ice Cap (CIC). Atmospheric drying favored by a poleward migration of the SWW induced a dramatic shrinkage of the CIC over the past 50 years. Current knowledge of how this decline compares with the natural variability of the CIC is unclear and based exclusively on geomorphological records with limited temporal resolution. This paper introduces a 4 kyr marine record built from a transect of giant piston cores collected in Table Fjord, southwestern margin of the CIC. Interpretation of sedimentary and geochemical proxies is supported by statistical correlations with the CIC surface mass balance on the instrumental timescale, and by the age overlapping with dated landforms and deposits over the last two millennia. High-resolution geochronological data (137Cs and 210Pb inventories along with 63 AMS 14C dates) corrected from a local marine reservoir age allowed reconstructing glacier variability at a multidecadal resolution. The CIC was paced by periods of glacial advances at 3.4–2.8, 2.3–1.7, and 1.35–1.15 ka cal BP, followed by a two-stage ‘Little Ice Age’ maximum between 0.7 ka cal BP and the early 20th century. Comparison with paleoenvironmental records from the subantarctic fringe zone and the southern mid-latitudes suggests SWW-driven precipitation (wetter and windier conditions) were the main driver of centennial-scale glacier variability in the Kerguelen Islands, notably after 2.3 ka cal BP. The Kerguelen record thereby supports a zonally-synchronous, hemispheric-wide SWW pattern pacing Southern Ocean climatic variability in a SAM-like mode. The Little Ice Age maximum ice extent results from the coincidence of cold conditions caused by an equatorward shift of the Polar Front, an oceanic front bordering the Kerguelen archipelago resulting in lower sea surface temperatures, together with wetter conditions favored by strengthened SWW.

Insights into Blue Whale (Balaenoptera musculus L.) Population Movements in the Galapagos Archipelago and Southeast Pacific.

The Galapagos Marine Reserve is vital for cetaceans, serving as both a stopover and residency site. However, blue whales, occasionally sighted here, exhibit poorly understood migratory behavior within the Galapagos and the broader Eastern Tropical Pacific. This study, the first to satellite tag blue whales in the Galapagos (16 tagged between 2021 and 2023), explored their behavior in relation to environmental variables like chlorophyll-a concentration, sea surface temperature (SST), and productivity. Key findings show a strong correlation between foraging behavior, high chlorophyll-a levels, productivity, and lower SSTs, indicating a preference for food-rich areas. Additionally, there is a notable association with geomorphic features like ridges, which potentially enhance food abundance. Most tagged whales stayed near the Galapagos archipelago, with higher concentrations observed around Isabela Island, which is increasingly frequented by tourist vessels, posing heightened ship strike risks. Some whales ventured into Ecuador's exclusive economic zone, while one migrated southward to Peru. The strong 2023 El Niño-Southern Oscillation event led to SST and primary production changes, likely impacting whale resource availability. Our study provides crucial insights into blue whale habitat utilization, informing adaptive management strategies to mitigate ship strike risks and address altered migration routes due to climate-driven environmental shifts.

Decline in the West Greenland population of a zooplanktivorous seabird, the little auk Alle alle

The warming of the Arctic had lead to a diverse range of impacts on local biota, including northward shifts of some species range. Here, we report past and present distribution and abundance of an Arctic zooplanktivorous seabird, the little auk Alle alle in West Greenland south of 74° N, and examine the changes in sea surface temperature (SST) and sea ice concentration (SIC) in the birds foraging areas in 1850–2007. We estimated the little auk population in the studied region to be 5,200 pairs in the 1930s, 6,000–6,500 pairs in the 1940-1970s and 70–80 pairs by the 2000s. We found that periods with increased SST and reduced SIC, especially in the last few decades, coincided with little auk population declines. Besides, years with little auk presence in breeding sites were characterized by either low SST and low to moderate SIC or higher SST but moderate to high SIC. Observed contraction of the breeding range and a decrease in abundance of the little auk may be attributed to more complex climate-driven changes in the marine ecosystem at finer spatial and temporal scales and/or cannot be easily detected given the coarseness of data used. It is possible that the population in this region has never been very numerous being subjected to local impacts such as disease, bycatch, predation, etc. The climate warming that is currently being observed, along with corresponding shifts in zooplankton communities, may lead to extirpation of the studied little auk populations.

Wave‐Coupled Effects on Oceanic Biogeochemistry: Insights From a Global Ocean Biogeochemical Model in the Southern Ocean

AbstractOceanic biogeochemistry plays a pivotal role in regulating Earth's climate system by governing the cycling of key elements such as carbon, oxygen, and nutrients. Various metocean processes including wind, tides, currents, waves, and eddies significantly influence the dynamics of this system. In particular, ocean surface waves contribute to this intricate interplay by facilitating the exchange of heat, gas, and momentum between the atmosphere and the ocean. Although wave‐coupled effects are substantial, studies on their impacts on oceanic biogeochemistry, particularly on phytoplankton abundance are missing in present‐day research. Additionally, wave‐coupled effects cannot be disregarded in regions like the Southern Ocean (SO), where wind and waves activities are prominent. Addressing this gap, we incorporated a parameterization of surface wave mixing into a global ocean biogeochemical model to investigate its effects on upper ocean and biogeochemical parameters. Our results show that surface wave mixing has significant impacts on sea surface temperature (SST), mixed layer depth (MLD), and nutrient distribution—key factors that influence phytoplankton growth. Additionally, we observed significant improvements in model biases against the observations. During austral summer, additional mixing from surface waves can significantly lower SST by 0.5°C, deepen MLD by 13 m, and enhance Chlorophyll‐a (Chl‐a) concentration, an index of phytoplankton population, by 8% in the SO. This observed increase in Chl‐a concentration is mainly driven by enhanced dissolved iron levels resulting from wave‐induced mixing. Our findings underscore the significance of incorporating surface wave mixing in ocean biogeochemistry studies, an aspect that is currently overlooked.

Satellite observed oceanographic drivers of Mobulidae fisheries catch in the Southeast Indian Ocean

Indonesian coastal waters include several marine megafauna biodiversity hotspots. Several fish populations of ecological and socio-economic importance, such as elasmobranchs (sharks and rays), have experienced rapid decline due to unsustainable human activities, primarily overfishing. Small-scale fisheries (SSF) are currently exempt from governmental fisheries management measures despite contributing a significant proportion of a total catch. The Generalised Additive Models were used to investigate the effect of variations in oceanographic parameters of the Teluk Penyu fishing ground, south of central Java, on the magnitude of Mobulidae (Mobula spp.) catch based on its landings data over ten years (2009–2018) from one of Indonesia's largest ports, Cilacap, Central Java, Indonesia. Mobulidae catch from Teluk Penyu fishing ground was generally higher from June to November when the water exhibited relatively high sea surface salinity (sal >34.1 ‰), chlorophyll (0.32–0.45 mg/m3), and nitrate (nit >0.0045 mg NO3/m3), water speed (>0.29 m/s) and eddy kinetic energy (>0.04 m3/s2) levels, and relatively low sea surface temperature (<28 °C), oxygen (<0.182 mg O2/m3) and sea surface height (<0.9 m) levels than the other months of the year. This study reveals that satellite Earth Observation (EO) data provided a preliminary relationship between oceanographic conditions and the amount of catch for developing more effective management and conservation measures for endangered species like Mobulidae. Utilizing EO data may also be applied to help inform much-needed ecosystem-based management measures, including habitat protection and bycatch reduction for conserving endangered Mobulidae species in the Southeast Indian Ocean. The in-situ onboard ocean observation and temporal species-specific catch data will greatly complement the current work.

Understanding environmental drivers and trends in chlorophyll-a and related factors across equatorial Indian Ocean regions: implications for marine ecosystem dynamics and vulnerability

ABSTRACT We estimated the concentration of Chlorophyll-a (Chl-a) along with physical and biological factors including sea surface temperature (SST), wind speed and concentration of nitrate and phosphate in the Western, Central and Eastern Equatorial Indian Oceans (WEIO, CEIO and EEIO) using data from the Copernicus Marine Service and ERA-5 for the years 1994 to 2019. Our results show that along with the concentration of Chl-a, nitrate and phosphate have decreased, and sea surface temperature has increased in the EEIO. Due to coastal upwelling off the coast of Somalia and offshore Ekman transport throughout the summer, the southwest monsoon caused a significant increase in concentrations of Chl-a, nitrate, phosphate and wind speed in WEIO during June-July-August-September (JJAS) and October-November-December (OND). SST decreased at this time and deeper water interacted with surface water, increasing biological production. In EEIO, the upwelling zone is primarily maintained by wind-induced divergence throughout the year, whereas stratification in winter prevented surface Chl-a increase. High wind speed and low SST led to increased productivity in WEIO. Comparison of EEIO with WEIO and CEIO demonstrates low levels of Chl-a, phosphate and nitrate. The trends signify that these oceanic zones are highly vulnerable to developing into ecological deserts in the near future.

Assessing the global distribution and risk of harmful microalgae: A focus on three toxic Alexandrium dinoflagellates

Harmful dinoflagellates and their resulting blooms pose a threat to marine life and human health. However, to date, global maps of marine life often overlook harmful microorganisms. As harmful algal blooms (HABs) increase in frequency, severity, and extent, understanding the distribution of harmful dinoflagellates and their drivers is crucial for their management. We used MaxEnt, random forest, and ensemble models to map the habitats of the representative HABs species in the genus Alexandrium, including A. catenella, A. minutum, and A. pacificum. Since species occurrence records used in previous studies were solely morphology-based, potentially leading to misidentifications, we corrected these species' distribution records using molecular criteria. The results showed that the key environmental drivers included the distance to the coastline, bathymetry, sea surface temperature (SST), and dissolved oxygen. Alexandrium catenella thrives in temperate to cold zones and is driven by low SST and high oxygen levels. Alexandrium pacificum mainly inhabits the Temperate Northern Pacific and prefers warmer SST and lower oxygen levels. Alexandrium minutum thrives universally and adapts widely to SST and oxygen. By analyzing the habitat suitability of locations with recorded HAB occurrences, we found that high habitat suitability could serve as a reference indicator for bloom risk. Therefore, we have proposed a qualitative method to spatially assess the harmful algae risk according to the habitat suitability. On the global risk map, coastal temperate seas, such as the Mediterranean, Northwest Pacific, and Southern Australia, faced higher risks. Although HABs currently have restricted geographic distributions, our study found these harmful algae possess high environmental tolerance and can thrive across diverse habitats. HAB impacts could increase if climate changes or ocean conditions became more favorable. Marine transportation may also spread the harmful algae to new unaffected ecosystems. This study has pioneered the assessment of harmful algal risk based on habitat suitability.

An Assessment of Changes in the Thermal Environment during the COVID-19 Lockdown: Case Studies from the Greenland and Norwegian Seas

The COVID-19 lockdown had a significant impact on human activities, reducing anthropogenic heat and CO2 emissions. To effectively assess the impact of the lockdown on the thermal environment, we used the sliding paired t-test, which we improved from the traditional sliding t-test by introducing the paired t-test for sliding statistical tests, to test the abrupt change in the thermal environment. Furthermore, an additive decomposition model and wavelet analysis method were used to analyze the characteristics of trend and irregular change, coherence, and phase difference of the time series data with respect to the thermal environment. We chose the Greenland Sea and the Norwegian Sea, regions highly sensitive to changes in climate and ocean circulation, as case studies and used remote sensing data of the sea surface temperature (SST) and the atmospheric CO2 concentration data obtained from the Goddard Earth Sciences Data and Information Services Center from January 2015 to December 2021 for the analysis. The results show that although the annual spatial mean SST in 2020 is lower than the mean of all 7 years in most areas of the two seas, there is no evidence of a significant mutation in the decrease in the SST during the lockdown in 2020 compared with the temperatures before, according to the sliding paired t-test. The analysis of the irregular components of the monthly mean SST decomposed by an additive decomposition model also does not show the anomalously low SST during the lockdown in 2020. In addition, the lockdown had almost no impact on the increasing trend of CO2 concentration. The wavelet analysis also shows that there is no obvious anomaly in coherence or phase difference between the periodic variation of the SST and the CO2 concentrations in 2020 compared with other years. These results suggest that the direct effect of the COVID-19 lockdown on the thermal environment of the study area could be negligible.

Regular widespread aggregations of the oceanic jellyfish Pelagia noctiluca in the northeast Atlantic over 11 years

The jellyfish Pelagia noctiluca form extensive aggregations in the Mediterranean Sea that can exert top-down control on prey and cause mass-mortalities in fish farms. The description of extensive aggregations of P. noctiluca in the northeast Atlantic in 2007 coupled with a subsequent mortality event of farmed salmon in Northern Ireland prompted further investigation of the species in this region. We collected standardised P. noctiluca biomass from 1938 fisheries trawls over 11 years (2008–2018) covering ∼200,000 km2 of northeast Atlantic shelf seas. While a linear trend in P. noctiluca was not identified, the mean annual biomass exhibited significant fluctuations, with particularly elevated levels in 2009, 2013, 2014 and 2016 (0.05, 0.02, 0.01 and 0.02 kg ha−1, respectively). Mean biomass was higher in the northern (0.028 kg ha−1) and western portions (0.005 kg ha−1) of the study area compared to the southwestern (0.003 kg ha−1) and southeastern portions (0.001 kg ha−1). A binomial generalised linear mixed model of P. noctiluca biomass data indicated that higher P. noctiluca occurrence was driven by a positive Eastern Atlantic Pattern index (strongest effect), south-easterly winds, a negative North Atlantic Oscillation index and lower sea-surface temperatures (weakest effect). The fixed effects accounted for 36.81% of the variance in P. noctiluca occurrence data, while a random year effect further explained an additional 24.06% of the variance. These conditions may destabilise the European Slope Current in autumn-winter which promotes the transport of P. noctiluca from oceanic sources onto the northeast Atlantic shelf. Our findings represent a dramatic shift in our understanding of this species in the northeast Atlantic which may have significant ecological impacts, from predation on fish eggs and larvae to providing food for oceanic sunfish.

Predicting the dynamics of per- and polyfluoroalkyl substances in coastal regions of Africa: vulnerability index and adverse ecological pathways from remote-sensed variables.

This study aimed to predict the dynamics of per- and polyfluoroalkyl substance (PFAS) contamination and ecological vulnerability within coastal regions of Africa utilizing time-averaged remote-sensed data patterns from 2020 to 2023. The analysis identified PFAS contamination hotspots along the coast of Africa, particularly in western Africa around Nigeria and in areas spanning Equatorial Guinea and Guinea-Bissau, with risk influenced by eastward wind patterns, overland runoff, and elevated aerosol optical depth (AOD) values. Regional trends indicated that variations in solar energy absorption and surface air temperature could influence PFAS dynamics in North Africa, South Africa, East Africa, and West Africa. In North Africa, intermediate overland runoff and lower sea-surface temperatures were observed. In South Africa, there were intermediate runoff levels and warmer sea-surface temperatures. East Africa experienced intermediate runoff as well. In West Africa, there was increased susceptibility to high overland runoff and aerosol-related PFAS contamination. From the weighted vulnerability index, significant disparities in environmental conditions across African coastal regions revealed that North Africa had relatively lower vulnerability, while West Africa had the highest susceptibility to per- and polyfluoroalkyl substance (PFAS) contamination. This study emphasizes the necessity for region-specific vulnerability index models and targeted mitigation strategies to address diverse ecological and health risks from PFAS contamination along the African coast. Regional and international collaboration, spearheaded by organizations such as the AU and ECOWAS, is essential, with tailored policies aligned with the SDGs, Agenda 2063, and NEPAD crucial for effective environmental management, urging policymakers to prioritize cooperation and resource sharing for comprehensive sustainability goals.

Eastern Boundary Upwelling Systems in Ocean–Sea Ice Simulations Forced by CORE and JRA55-do: Mean State and Variability at the Surface

Abstract In this paper we summarize improvements in climate model simulation of eastern boundary upwelling systems (EBUS) when changing the forcing dataset from the Coordinated Ocean-Ice Reference Experiments (CORE; ∼2° winds) to the higher-resolution Japanese 55-year Atmospheric Reanalysis for driving ocean–sea ice models (JRA55-do, ∼0.5°) and also due to refining ocean grid spacing from 1° to 0.1°. The focus is on sea surface temperature (SST), a key variable for climate studies, and which is typically too warm in climate model representation of EBUS. The change in forcing leads to a better-defined atmospheric low-level coastal jet, leading to more equatorward ocean flow and coastal upwelling, both in turn acting to reduce SST over the upwelling regions off the west coast of North America, Peru, and Chile. The refinement of ocean resolution then leads to narrower and stronger alongshore ocean flow and coastal upwelling, and the emergence of strong across-shore temperature gradients not seen with the coarse ocean model. Off northwest Africa the SST bias mainly improves with ocean resolution but not with forcing, while in the Benguela, JRA55-do with high-resolution ocean leads to lower SST but a substantial bias relative to observations remains. Reasons for the Benguela bias are discussed in the context of companion regional ocean model simulations. Finally, we address to what extent improvements in mean state lead to changes to the monthly to interannual variability. It is found that large-scale SST variability in EBUS on monthly and longer time scales is largely governed by teleconnections from climate modes and less sensitive to model resolution and forcing than the mean state.

Seasonal variations in chlorophyll–a and sea surface temperature in the exclusive economic zone of Sri Lanka

Oceanic phytoplankton plays a crucial role in regulating the biogeochemical cycle in marine ecosystems. Light harvesting pigments such as chlorophyll–a (chl–a) can be used to understand marine primary productivity, especially phytoplankton abundance. Sea surface temperature is closely linked with phytoplankton abundance and climatic changes. The objective of the current study is to determine spatial and temporal variations of chl–a and sea surface temperature and their co-variation, over 12 years using statistical methodologies and Remote Sensing, Geographic Information System (GIS) and Cloud Computing Approach. In this study, the available sea surface temperature and chl–a data acquired from a Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor were proceeded through Google Earth Engine and Earth Science Data System. Data visualization was carried out using ArcMap™ software. Results show a weak negative linear relationship (−0.40, P < 0.05) between sea surface temperature and chl–a. Therefore, additional favorable environmental factors such as coastal upwelling, and nutrient discharge through river run-off can control the primary productivity of phytoplankton. We also illustrated spatial and temporal maps for chl–a and sea surface temperature distribution in the exclusive economic zone of Sri Lanka. Chlorophyll–a concentration is enhanced during the southwest monsoon, and the lowest concentration is observed during the first inter-monsoon period. Next, the highest sea surface temperature is recorded during the first inter-monsoon period, and the lowest sea surface temperature is observed during the northeast monsoon. Seasonal behavior of chl–a concentration and sea surface temperature are changed as chl–a (SWM) > chl–a (NEM) > chl–a (SIM) > chl–a (FIM) and SST (FIM) > SST (SIM) > SST (SWM) > SST (NEM), respectively. In addition, both trend lines for each variable show a positive gradient, which may be attributed to global warming. Finally, we observed the alteration of chl–a and sea surface temperature that linked to changes in ocean chemistry during the global COVID–19 pandemic.

The Dipole Mode of Summer Wet‐Bulb Temperature Over Eastern China and the Possible Mechanisms

AbstractOne prominent mode of the variability in the summer wet‐bulb temperature (WBT) over eastern China exhibits a distinct north‒south dipole pattern. This pattern demonstrates a positive center in northern China (NC), while a negative center is observed in southern China (SC). Our results indicate that the dipole mode of WBT could be partially ascribed to the impact of spring snow anomalies in eastern Europe–western Siberia (EEWS). The reduction in the snow depth, coupled with dry soil conditions, enhances the surface heat flux and consequently leads to an increase in the near‐surface air temperature. The signal of soil moisture could persist from spring to summer, stimulating the generation of zonal Rossby waves. Consequently, the significant wave flux anomalies propagate from EEWS downstream and influence the atmospheric circulation over eastern China. These patterns play a role in the increase in the surface air temperature and moisture accumulation over NC, ultimately leading to the establishment of the dipole mode of WBT over eastern China in summer. Further analysis indicates that the atypical low sea surface temperature in the tropical Ocean, induced by the El Niño‐Southern Oscillation, establishes a climatic context favorable for the persistence of an anomalous cyclone in the Northwest Pacific (NWP) throughout the summer season. The strengthened convection over the NWP and SC induces a dipole pattern of atmospheric circulation by stimulating a meridional wave train. This pattern creates favorable temperature and moisture conditions, contributing to the development of the dipole mode of the summer WBT across eastern China.

Contribution of anthropogenic aerosols to persistent La Niña-like conditions in the early 21st century

The discrepancy between the observed lack of surface warming in the eastern equatorial Pacific and climate model projections of an El Niño-like warming pattern confronts the climate research community. While anthropogenic aerosols have been suggested as a cause, the prolonged cooling trend over the equatorial Pacific appears in conflict with Northern Hemisphere aerosol emission reduction since the 1980s. Here, using CESM, we show that the superposition of fast and slow responses to aerosol emission change-an increase followed by a decrease-can sustain the La Niña-like condition for a longer time than expected. The rapid adjustment of Hadley Cell to aerosol reduction triggers joint feedback between low clouds, wind, evaporation, and sea surface temperature in the Southeast Pacific, leading to a wedge-shaped cooling that extends to the central equatorial Pacific. Meanwhile, the northern subtropical cell gradually intensifies, resulting in equatorial subsurface cooling that lasts for decades.

Radiative Impacts of Californian Marine Low Clouds on North Pacific Climate in a Global Climate Model

Abstract The northeastern Pacific climate system features an extensive low-cloud deck off California on the southeastern flank of the subtropical high that accompanies intense northeasterly trades and relatively low sea surface temperatures (SSTs). This study assesses climatological impacts of the low-cloud deck and their seasonal differences by regionally turning on and off the low-cloud radiative effect in a fully coupled atmosphere–ocean model. The simulations demonstrate that the cloud radiative effect causes a local SST decrease of up to 3°C on an annual average with the response extending southwestward with intensified trade winds, indicative of the wind–evaporation–SST (WES) feedback. This nonlocal wind response is strong in summer, when the SST decrease peaks due to increased shortwave cooling, and persists into autumn. In these seasons when the background SST is high, the lowered SST suppresses deep-convective precipitation that would otherwise occur in the absence of the low-cloud deck. The resultant anomalous diabatic cooling induces a surface anticyclonic response with the intensified trades that promote the WES feedback. Such seasonal enhancement of the atmospheric response does not occur without air–sea couplings. The enhanced trades accompany intensified upper-tropospheric westerlies, strengthening the vertical wind shear that, together with the lowered SST, acts to shield Hawaii from powerful hurricanes. On the basin scale, the anticyclonic surface wind response accelerates the North Pacific subtropical ocean gyre to speed up the Kuroshio by as much as 30%. SST thereby increases along the Kuroshio and its extension, intensifying upward turbulent heat fluxes from the ocean to increase precipitation.

Identifying the ecologically significant habitats of Yellow-fin tuna (Thunnus albacares, Bonnaterre, 1788) of Iranian purse seine fishery in the Gulf of Oman and Indian Ocean: An approach using satellite imagery and fishery data

Ecological fluctuations are influential factors affecting marine fish populations. The main primary objective of this study was to determine the catch probability of yellowfin tuna (Thunnus albacares, Bonnaterre, 1788) in the Indian Ocean and the Gulf of Oman, as well as its environmental preferences. This study employs generalized additive models (GAMs) to examine the spatiotemporal pattern of yellowfin tuna purse seiners, placing particular emphasis on the analysis of satellite imagery and environmental data. The results derived from the GAMs showed that the presence of yellowfin tuna was related to factors including sea surface height (SSH), salinity (SAL), latitude, and sea surface current velocities (velocity). Based on the findings of this research, it can be concluded that Iranian waters of the Gulf of Oman provide suitable habitats for yellowfin tuna during the autumn season, while in the Indian Ocean, these conditions are observed during the summer. Furthermore, the probability of successfully catching yellowfin tuna is higher in the Gulf of Oman than in the studied region of the Indian Ocean, with the catch probability predicted to be higher between 57°E and 69°E and for latitudes ranging from 5°N to 5°S and 20°−25°N. The study also found that areas with a sea surface temperature (SST) of 23–33 °C, SSH of 151–223 cm, and chlorophyll-a (Chl-a) concentration of 0.08–0.6 mg/m3 achieve higher catches than those with low SST, SSH, and Chl-a concentration. The model trained with data from all seasons was used to examine the seasonal variation in potential fishing grounds. Yellowfin tuna abundance varies seasonally and from year to year, depending on sea conditions and their behavior.

Spatiotemporal variation of snow cover days and influencing factors on the Loess Plateau during 2000–2019

Identifying the large-scale teleconnection is of great practical significance to comprehend the formation mechanism of snow cover days (SCDs) anomalies and improve the disaster risk management of ecological construction on the Loess Plateau. Based on Terra Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover days datasets from 2000 to 2020, we analyzed the spatiotemporal variation of SCDs on the Loess Plateau. Meanwhile, we identified the variability in large-scale atmospheric patterns associated with SCDs on the Loess Plateau. The results show that: in the past 20 years have revealed an interdecadal fluctuations of SCDs on the Loess Plateau. Spatially, the SCDs experienced a significant decreasing trend (p < 0.05) in only 13.1% of the regions, which were distributed in the Northern Earth-Rock Mountain and Hully and Gully Loess Region. The effects of climate-related factor variations on SCD dynamics showed obvious spatial and monthly differences. Specifically, SCDs dominated by precipitation were significantly positively correlated in the north-eastern part of the Loess Plateau. Temperature plays a decisive role in SCD dynamics in the southern part of the Loess Plateau. Among the influencing factors, the East Asian Trough Intensity (EATI), the Asian Polar Vortex Area index (APVA) and the sea surface temperature (SST) anomalies in the NINO W region are three effective indictors of SCDs anomaly. In January, with the deepening of East Asian Trough and low SST in the NINO W region (0°∼10°N, 140°E∼180°E), East Asian winter monsoon is relatively strengthening, temperature is lower on the Loess Plateau, leading to more SCDs in the southern study region. The bigger APVA, corresponding to more snow accumulation in December, could effectively prolong the SCDs dominated by precipitation on the Loess Plateau. The conclusions of this study have implications for excavating early warning information of snow cover anomalies on the Loess Plateau.

Marine distribution and habitat use by Snow Petrels Pagodroma nivea in East Antarctica throughout the non-breeding period

The relationships between flying Antarctic seabirds and their at-sea environments remain poorly understood, particularly outside of the breeding season. Improving our knowledge of how these marine predators use their habitat is a critical step towards conservation of these species. We tracked 27 adult Snow Petrels from two large breeding colonies in East Antarctica during the Austral winter (non-breeding period) – when they are primarily at sea away from their nesting sites. During this time, Snow Petrel habitat use was most associated with bathymetry (&amp;gt; 5000 m), low sea-surface height, relatively close distance to the southern boundary of the Antarctic Circumpolar Current, relatively close distance to the ice-edge, relatively high sea-ice concentration, and low sea-surface temperature. Individuals displayed various movement patterns: 20 birds occupied overlapping winter areas that ranged broadly (up to 2000 km) from their breeding sites. The remaining birds ventured far beyond their breeding sites – reaching a maximal distance from the colony of 5,268 km. One individual circumnavigated Antarctica. Daily activity patterns were related to day length, with peak activity occurring near dawn and dusk. Nocturnal activity increased from March until August/September. Key results reveal and depict Snow Petrel habitat maps for the non-breeding period in the East Antarctic region.