Sea Surface Temperature Variability Research Articles

Coastal and regional marine heatwaves and cold spells in the northeastern Atlantic

Abstract. The latest Intergovernmental Panel on Climate Change (IPCC) report describes an increase in the number and intensity of marine heatwaves (MHWs) and a decrease in marine cold spells (MCSs) in the global ocean. However, these reported changes are not uniform on a regional to local basis, and it remains unknown if coastal areas follow the open-ocean trends. Surface ocean temperature measurements collected by satellites (from 1982–2022) and 13 coastal buoys (from 1990–2022) are analyzed in the northeastern Atlantic and three subregions: the English Channel, Bay of Brest and Bay of Biscay. The activity metric, combining the number of events, intensity, duration and spatial extent, is used to evaluate the magnitude of these extreme events. The results from in situ and satellite datasets for each of the studied regions are quite in agreement, although the satellite dataset underestimates the amplitude of activity for both MHWs and MCSs. This supports the applicability of the method to both in situ and satellite data, albeit with caution on the amplitude of these events. Also, this localized study in European coastal northeastern Atlantic water highlights that similar changes are being seen in coastal and open oceans regarding extreme events of temperature, with MHWs being more frequent and longer and extending over larger areas, while the opposite is seen for MCSs. These trends can be explained by changes in both the mean of and variance in sea-surface temperature. In addition, the pace of evolution and dynamics of marine extreme events differ among the subregions. Among the three studied subregions, the English Channel is the region experiencing the strongest increase in summer MHW activity over the last 4 decades. Summer MHWs were very active in the English Channel in 2022 due to long events, in the Bay of Biscay in 2018 due to intense events and in the Bay of Brest in 2017 due to a high occurrence of events. Winter MCSs were the largest in 1987 and 1986 due to long and intense events in the English Channel. Finally, our findings suggest that at an interannual timescale, the positive North Atlantic Oscillation favors the generation of strong summer MHWs in the northeastern Atlantic, while low-pressure conditions over northern Europe and a high off the Iberian Peninsula in winter dominate for MCSs. A preliminary analysis of air–sea heat fluxes suggests that, in this region, reduced cloud coverage is a key parameter for the generation of summer MHWs, while strong winds and increased cloud coverage are important for the generation of winter MCSs.

Quantification of the interannual variability of the nationwide electric power supply from photovoltaic systems in Japan

Information on the variation in photovoltaic (PV) power generation is essential for resource assessment. This work investigated the interannual variability of the nationwide electric power supply from PV systems in Japan. Objectives of this study were twofold: one was the quantification of the annual variability of the nationwide PV power supply. The other was identifying the causes of the variability. However, the time span of available observation data on the PV power supply is inadequate to evaluate its variability, as PV systems have been rapidly installed in recent years. We used simulation to bypass this limitation. Due to the lack of available information for modeling, a hybrid modeling approach, combining a parametric model, and estimating parameters by fitting the model to observations, was employed. Nationwide PV power supply simulations were performed using historical weather data for 30 years, from 1991–2020. The long-term simulation data enabled us to quantify the interannual variability of the nationwide PV power generation. The annual variability measured with the range from the minimum to the maximum was approximately 9% of the mean. The variability for each month was less than 30% of the monthly mean for every month except for July when it was approximately 40%. An increasing trend in the annual mean PV power supply was observed over the 30 years, with an increase of 0.16% per year of the mean over the whole period. We found that the variations in sea surface temperature (SST) in the Tropics are factors contributing to the variability of nationwide PV power supply. Specifically, the variation in SST in the tropical Indian Ocean is one of the possible driving factors of the annual variability. The framework proposed in this study can provide valuable information for assessing solar energy resources on an interannual scale.

РОЛЬ ИЗМЕНЕНИЙ АТМОСФЕРНОЙ ЦИРКУЛЯЦИИ В УВЕЛИЧЕНИИ ПОВТОРЯЕМОСТИ ЛЕТНИХ ЗАСУХ НА ЕВРОПЕЙСКОЙ ЧАСТИ РОССИИ

According to the Standardized Precipitation Evapotranspiration Index (SPEI), most extensive summer droughts in European Russia south of 55°N in 1950-2021 were observed during the extremely negative phases of the Eastern Atlantic/Western Russia (EAWR) and West Pacific (WP) atmospheric circulation patterns characterized by abnormal high atmospheric pressure and an increased frequency of the number of days with atmospheric blocking over European Russia. It is shown that the frequency of droughts in the study area in the years of the negative phases of both circulation indices and their extremes in the summer months as compared to other years was higher by five droughts per decade in the Volga and Central Chernozem regions and by three droughts per decade in the northwestern Caspian region. A statistically significant correlation was found between the EAWR in summer and the multidecadal variability of sea surface temperature in the North Atlantic. It was revealed that the increase in the drought frequency in the study area in recent decades has been caused by the restructuring of atmospheric circulation in the Euro-Atlantic sector accompanying the transition of the Atlantic Multidecadal Oscillation (AMO) to a positive phase. An increase in the stability of the EAWR and WP atmospheric circulation patterns was observed, as well as a related significant increase in the frequency of extensive droughts in the study area in 2010-2021. They were accompanied by the weakening of zonal atmospheric circulation in the Northern Hemisphere, the combination of the positive AMO phase and the effects of anthropogenic warming on the atmospheric circulation in the

Last glacial hydroclimate variability in the Yucatán Peninsula not just driven by ITCZ shifts

We reconstructed hydroclimate variability in the Yucatán Peninsula (YP) based on stalagmite oxygen and carbon isotope records from a well-studied cave system located in the northeastern YP, a region strongly influenced by Caribbean climate dynamics. The new stalagmite isotopic records span the time interval between 43 and 26.6 ka BP, extending a previously published record from the same cave system covering the interval between 26.5 and 23.2 ka BP. Stalagmite stable isotope records show dominant decadal and multidecadal variability, and weaker variability on millennial timescales. These records suggest significant precipitation declines in the broader Caribbean region during Heinrich events 4 and 3 of ice-rafted discharge into the North Atlantic, in agreement with the antiphase pattern of precipitation variability across the equator suggested by previous studies. On millennial timescales, the stalagmite isotope records do not show the distinctive saw-tooth pattern of climate variability observed in Greenland during Dansgaard–Oeschger (DO) events, but a pattern similar to North Atlantic sea surface temperature (SST) variability. We propose that shifts in the mean position of the Intertropical Convergence Zone (ITCZ), per se, are not the dominant driver of last glacial hydroclimate variability in the YP on millennial timescales but instead that North Atlantic SSTs played a dominant role. Our results support a negative climate feedback mechanism whereby large low latitude precipitation deficits resulting from AMOC slowdown would lead to elevated salinity in the Caribbean and ultimately help reactivate AMOC and Caribbean precipitation. However, because of the unique drivers of future climate in the region, predicted twenty-first century YP precipitation reductions are unlikely to be modulated by this negative feedback mechanism.

Varying Relationship between La Niña and SST Anomalies in the Kuroshio and Adjacent Regions during Boreal Winter: Role of the East Asian Winter Monsoon

Abstract The winter sea surface temperature (SST) anomalies in the Kuroshio and adjacent regions (KAR), which greatly influence the East Asian–North Pacific–North American climate, are closely related to El Niño–Southern Oscillation (ENSO). This SST relationship between the KAR and the equatorial eastern-central Pacific is widely assumed to be symmetric between El Niño and La Niña. Compared to previous studies indicating the significant and strong KAR warming during El Niño winters, this study indicates weakly negative KAR SST anomalies in the composite analysis for all La Niña events. Positive winter KAR SST anomalies unexpectedly appear in approximately half of La Niña events, which counteract negative SST anomalies in the rest of La Niña events. Further analysis suggests that the impact of La Niña on KAR SST anomalies is modulated by the East Asian winter monsoon (EAWM) during early winter. The weaker-than-normal EAWM offsets the anomalous northeasterly winds in the KAR induced by La Niña and then reinforces the KAR warming through warm oceanic advection. As for strong EAWM, it enhances the northeasterly winds to the west of an anomalous Philippine Sea cyclone associated with La Niña, leading to KAR cooling with more latent heat flux loss from the ocean and anomalous cold oceanic advection. Additionally, when the EAWM is independent of ENSO and is associated with the western Pacific pattern, it also can exhibit a pronounced influence on the KAR SST anomalies via the major processes of surface latent flux and horizontal heat advection in the ocean, accompanied by a change in Kuroshio transport. Significance Statement The interannual variability of SST from Philippine Sea to the Kuroshio and adjacent regions is considered an important forecast factor of the eastern China climate. Previous studies have reported a dipole SST pattern with Philippine Sea cooling and warming in the Kuroshio and adjacent regions during El Niño winter is dominant, and simply regarded that the effect of La Niña on western North Pacific SST anomalies was a mirror image of that of El Niño events. Here, we have found two distinctive SST patterns in the western North Pacific during La Niña winter. One type is the dipole SST pattern, characterized by Philippine Sea warming and by cooling in the Kuroshio and adjacent regions. The other type is the monopole SST pattern with uniform warming expanding from the Philippine Sea to the Kuroshio and adjacent regions. The dipole (monopole) SST pattern in western North Pacific is modulated by La Niña and a strong (weak) EAWM. Analysis shows that the above two SST patterns during La Niña winter are equally important during 1950–2021. This study has identified the influence of the EAWM independent of ENSO on the SST anomalies in the Kuroshio and adjacent regions.

Observed Relative Contributions of Anomalous Heat Fluxes and Effective Heat Capacity to Sea Surface Temperature Variability

AbstractSea surface temperatures (SSTs) vary not only due to heat exchange across the air‐sea interface but also due to changes in effective heat capacity as primarily determined by mixed layer depth (MLD). Here, we investigate seasonal and regional characteristics of the contribution of MLD anomalies to the month‐to‐month variability of SST using observational datasets. First, we propose a metric called Flux Divergence Angle, which can quantify the relative contributions of surface heat fluxes and MLD anomalies to SST variability. Using this metric, we find that MLD anomalies tend to amplify SST anomalies in the extra‐tropics, especially in the eastern ocean basins, during spring and summer. In contrast, MLD anomalies tend to suppress SST anomalies in the eastern tropical Pacific during December‐January‐February. This paper provides the first global picture of the observed importance of MLD anomalies to the local SST variability.

Large-scale sea ice-Surface temperature variability linked to Atlantic meridional overturning circulation.

Due to its involvement in numerous feedbacks, sea ice plays a crucial role not only for polar climate but also at global scale. We analyse state-of-the-art observed, reconstructed, and modelled sea-ice concentration (SIC) together with sea surface temperature (SST) to disentangle the influence of different forcing factors on the variability of these coupled fields. Canonical Correlation Analysis provides distinct pairs of coupled Arctic SIC-Atlantic SST variability which are linked to prominent oceanic and atmospheric modes of variability over the period 1854-2017. The first pair captures the behaviour of the Atlantic meridional overturning circulation (AMOC) while the third and can be associated with the North Atlantic Oscillation (NAO) in a physically consistent manner. The dominant global SIC-Atlantic SST coupled mode highlights the contrast between the responses of Arctic and Antarctic sea ice to changes in AMOC over the 1959-2021 period. Model results indicate that coupled SST-SIC patterns can be associated with changes in ocean circulation. We conclude that a correct representation of AMOC-induced coupled SST-SIC variability in climate models is essential to understand the past, present and future sea-ice evolution.

Multi-scale variability features of global sea surface temperature over the past century

Understanding the multi-scale variabilities of global sea surface temperature (GSST) is extremely critical for deepening the comprehension of surface climate change. Great efforts have been made to study the multi-scale features of GSST, however, aiming to fully reveal the local features, here we propose a combined approach, incorporating an adaptive method named Ensemble Empirical Mode Decomposition (EEMD), and Pairwise-Rotated EOF (REOF), to separate signals on various frequency bands and eliminate the confounded EOF signatures. The results show that the explained variance of high-frequency components (HFC) in the equatorial central-eastern and south mid-latitude Pacific could reach more than 60%. The grid points where the variance contributions of low-frequency components (LFC) are greater than 40% are mainly concentrated in the subpolar North Atlantic and the Southern Ocean in both Pacific and Atlantic sectors, while that for secular trend (ST) hitting beyond 60% are displayed in the North Indian Ocean, the Southern Ocean from the tip of southwest Africa expanded to the southern side of Australia, Indo-western Pacific, east of the continents in both hemispheres and tropical Atlantic. By applying the EOF/REOF analysis, the leading modes of the HFC, LFC, and ST are then yielded. It is found that the patterns of the HFC are associated with El Niño-South Oscillation (ENSO) diversity, inferring the dominance and independence of the Eastern Pacific (EP) and Central Pacific (CP) El Niño. Meanwhile, Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) emerge in the rotated modes of the LFC, with the former exhibiting an Atlantic-Pacific coupling.

Pemetaan Zona Potensial Penangkapan Ikan (ZPPI) Di Perairan Selat Bali Menggunakan Citra Satelit Aqua MODIS


 
 
 
 The abundance and distribution of fish are influenced by environmental productivity, such as chlorophyll-a distribution and variations in sea surface temperature (SST). The lack of technology fishermen use in the waters of the Bali Strait has resulted in the high potential of fish resources not being optimally utilized. This study aimed to determine potential fishing zones by utilizing Aqua MODIS satellite data which can detect SST and chlorophyll-a. The image data observed was from October to December 2018 to 2020. The method used is the Single Image Edge Detection Algorithm, where this algorithm is used to determine potential fishing areas designed to detect fronts in SST images. The results showed that in December 2018, 7 potential fishing points were produced, marked with a chlorophyll-a value of 0.25 mg/m3 and an SST of 29.25°C. In December 2020, 82 potential fishing points were produced, with a chlorophyll-a value of 0.31 mg/m3 and an SPL of 29.79°C. Validation was carried out by analyzing the result of image processing with fish catch data obtained from Pengambengan PPN, Muncar PPP, and Kedonganan TPI. SST, with a value of 27°C, is the ideal temperature for fish where when the temperature increases, the number of potential fish catch points decreases and vice versa. The distribution of chlorophyll-a content with a value of > 0.2 mg/m3 affects the number of potential fishing points, where the higher the chlorophyll-a content, the more fishing ground points and vice versa.
 
 
 

Long-Term Variability in Sea Surface Temperature and Chlorophyll a Concentration in the Gulf of California

The Gulf of California (GC) is the only interior sea in the Eastern Pacific Ocean and is the most important fishing area in the northwestern region of the Mexican Pacific. This study focuses on the oceanographic variability of the GC, including its southern portion, which is an area with a high flow of energy and exchange of properties with the Pacific Ocean (PO), in order to determine its role in physical–biological cycles and climate change. The purpose of this work is to analyze the sea surface temperature (SST) and chlorophyll a concentration (Chl-a) during the period from 1998–2022 as indicators of long-term physical and biological processes, oceanographic variability, and primary production in the GC. In total, 513 subareas in the GC were analyzed, and a cluster analysis was applied to identify similar areas in terms of SST and Chl-a via the K-means method and using the silhouette coefficient (>0.5) as a metric to validate the clusters obtained. The trends of the time series of both variables were analyzed, and a fast Fourier analysis was performed to evaluate cycles in the series. A descriptive analysis of the SST and Chl-a series showed that the SST decreased from south to north. Six bioregions were identified using a combined of both SST and Chl-a data. The spectral analysis of the SST showed that the main frequencies in the six bioregions were annual and interannual (3–7 years), and the frequencies of their variations were associated with basin-level weather events, such as El Niño and La Niña. The SST in the GC showed a heating trend at an annual rate of ~0.036 °C (~0.73 °C in 20 years) and a decrease in Chl-a at an annual rate of ~0.012 mg/m3 (~0.25 mg/m3 in 20 years), with potential consequences for communities and ecosystems. Additionally, cycles of 10–13 and 15–20 years were identified, and the 10–13-year cycle explained almost 40–50% of the signal power in some regions. Moreover, mesoscale features (eddies and filaments) were identified along the GC, and they were mainly associated with the clusters of the SST. All these spatial and temporal variabilities induce conditions that generate different habitats and could explain the high biodiversity of the GC. If the warming trend of the SST and the decreasing trend of the Chl-a continue in the long term, concerns could be raised, as they can have important effects on the dynamics of this important marine ecosystem, including habitat loss for numerous native species, declines in the catches of the main fishery resources, and, consequently, support for the arrival of harmful invasive species.

Weakening of the Indian Ocean Dipole in the Mid-Holocene due to the Mean Oceanic Climatology Change

Abstract The Indian Ocean dipole (IOD) is one of the leading modes of interannual climate variability in the tropical Indian Ocean (IO). The paleoclimate provides real climate scenarios to examine IOD behaviors and the linkage to basic states. Based on 18 models from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5/6), the IOD change from the preindustrial period to the mid-Holocene is investigated. The multimodel mean reveals that the IOD variability weakens by 14%, as measured by the standard deviation of the dipole mode index, which is defined using the zonal sea surface temperature (SST) difference. Such attenuation is dominated by the spatially consistent suppression in the western-pole SST variability, while the eastern pole contributes little due to the opposite-signed changes in its northwestern and southeastern portions. The primary reason for the aforementioned changes comes from the altered climatic background, which displays a positive IOD-like pattern during IOD growing seasons, with intensified westward currents along the equator and northwestward currents in the southeastern equatorial IO. Such changes in the mean-state currents modulate the strength of the IOD-related anomalous advection and subsequently cause alterations in the IOD variability. Further analyses show that the IOD attenuation in the mid-Holocene is unlikely to be caused by the concurrently subdued El Niño–Southern Oscillation in the tropical Pacific, partially because of the diminished connections between the two oscillations themselves. The above simulated changes in both the IO mean climatology and IOD variability agree well with the available paleo records in literature. Significance Statement Understanding variations in the Indian Ocean dipole (IOD) and its relationship to the altered background mean state can advance our knowledge of tropical climate dynamics. The paleoclimate provides the opportunity to address this issue under real climate scenarios in the past. Based on multiple models from CMIP5/6, we investigate IOD changes during the mid-Holocene compared to the preindustrial period. The result shows a weakening of the IOD, and the main mechanism lies in the altered anomalous advection modulated by changes in the mean-state currents. The simulated changes in both the mean state and IOD variability are consistent with available paleo data. The present study extends the research scale of IOD dynamics beyond instrumental periods and provides scientific bases for deciphering geological records.

Applying deep learning to predict SST variation and tropical cyclone patterns that influence coral bleaching

South Penghu Marine National Park, Taiwan experienced severe coral bleaching in 2020 that may lead to coral mortality. Corals are important animals that enrich marine biodiversity, but several studies have shown that the range of sea surface temperature (SST) corals can survive is narrow, and recovery time can be as long as 10 years. The influences of climate change induced extreme weather should not be underestimated, and it is critical to accurately predict SST variations. In this study, a deep learning model, convolutional long short-term memory (ConvLSTM), which is a newer model suitable for estimating autocorrelated sequences, was built to predict daily SST for the next day, next week, and next two weeks, with the highest achieved 99.22% accuracy and a RMSE values of 0.2579. On the other hand, Penghu was not directly impacted by tropical cyclones in 2020; hence the lack of typhoon-induced SST cooling could be one of the reasons for extensive coral bleaching. The wind intensity, speed, as well as the thickness of ocean mixed layer all affect the variation of SST cooling. The results show that the degree heating weeks (DHWs) near Penghu achieved its highest level in 2020, and according to the analysis of the study, there is a clear association between climate change and coral bleaching risk increase in recent years. Therefore, we applied Random Forest to establish a machine learning model to classify whether a typhoon can trigger significant cooling. Model accuracy achieved 92.90% in the testing set, and empirical orthogonal function (EOF) analysis contributed the most to the SST cooling pattern among typhoons. This study provides a predictive contribution to global coral conservation for relevant institutions to know the risk beforehand, and they can discuss corresponding strategies and early warnings.

Simulations of the North Tropical Atlantic Mode–ENSO Connection in CMIP5 and CMIP6 Models

AbstractThe North Tropical Atlantic (NTA) mode is a dominant component of sea surface temperature (SST) variability over the northern tropical Atlantic, which is crucial to the occurrence of El Niño‐Southern Oscillation (ENSO). This study utilizes the historical simulation of the Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5 and CMIP6) to evaluate the simulations of the NTA mode and NTA–ENSO connection. We found that the CMIP5 and CMIP6 could reproduce the spatial pattern of the NTA mode similarly. Most of them could reasonably reproduce the spatial pattern of the NTA mode similar to the observation. Still, there are some differences in the central values and position of the NTA mode. In addition, the analysis further suggests that the CMIP5/CMIP6 models have a large diversity in the NTA–ENSO connection, which may be due to their differences in simulating the spring climatological mean Atlantic Intertropical Convergence Zone (ITCZ) precipitation and spring‐to‐summer NTA SST persistence. Models with stronger spring climatological mean Atlantic ITCZ precipitation in favor of the spring NTA‐related SST anomalies stimulate local precipitation anomalies, resulting in a more powerful atmospheric circulation reaction over the tropical Pacific. Additionally, the stronger spring‐to‐summer NTA SST persistence for sustaining the teleconnection, which constantly transmits impacts from the tropical Atlantic into the tropical Pacific. The CMIP6 models show improvements to the CMIP5 models regarding simulations of the spring climatological mean Atlantic ITCZ precipitation and spring‐to‐summer NTA SST persistence. Therefore, the CMIP6 models simulate the NTA–ENSO connection better than the CMIP5 models.

Antarctic sea ice variability linked to three dipole modes of subtropical sea surface temperature in the Southern Hemisphere

AbstractBased on statistical analyses of gridded data over the past four decades (1979–2020), we examined the teleconnection between the variability of the Antarctic sea ice and the leading modes of subtropical sea surface temperature (SST) variability known as the Indian Ocean subtropical dipole (IOSD), the South Atlantic subtropical dipole (SASD) and the South Pacific subtropical dipole (SPSD). We show that the pattern and strength of the teleconnection differ with the SST modes. For each mode, while the regional distributions of significant Antarctic sea ice anomalies are broadly similar throughout the year, the areal extent and the magnitudes of the anomalies display a strong seasonality. Larger areas and magnitudes of significant sea ice anomalies occur in austral winter for the SASD, autumn and spring for the SPSD and non‐summer seasons for the IOSD. We demonstrate that the spatial and seasonal variations of the sea ice anomalies associated with each of the three subtropical SST variability modes are largely consistent with the patterns of the anomalous temperature advection and sea ice transport by the anomalous atmospheric circulations induced by planetary wavetrains that are triggered by anomalous convective activities over different regions of subtropical oceans. These relationships between subtropical SST modes and Antarctic sea ice may serve as a valuable reference for predicting seasonal to interannual scale variations of Antarctic sea ice concentrations across each austral season.

Hysteresis of the El Niño-Southern Oscillation to CO2 forcing.

El Niño-Southern Oscillation (ENSO) is the strongest interannual climate variability with far-reaching socioeconomic consequences. Many studies have investigated ENSO-projected changes under future greenhouse warming, but its responses to plausible mitigation behaviors remain unknown. We show that ENSO sea surface temperature (SST) variability and associated global teleconnection patterns exhibit strong hysteretic responses to carbon dioxide (CO2) reduction based on the 28-member ensemble simulations of the CESM1.2 model under an idealized CO2 ramp-up and ramp-down scenario. There is a substantial increase in the ensemble-averaged eastern Pacific SST anomaly variance during the ramp-down period compared to the ramp-up period. Such ENSO hysteresis is mainly attributed to the hysteretic response of the tropical Pacific Intertropical Convergence Zone meridional position to CO2 removal and is further supported by several selected single-member Coupled Model Intercomparison Project Phase 6 (CMIP6) model simulations. The presence of ENSO hysteresis leads to its amplified and prolonged impact in a warming climate, depending on the details of future mitigation pathways.

Chasing Interannual Marine Paleovariability

AbstractSeveral modes of tropical sea‐surface temperature (SST) variability operate on year‐to‐year (interannual) timescales and profoundly shape seasonal precipitation patterns across adjacent landmasses. Substantial uncertainty remains in addressing how SST variability will become altered under sustained greenhouse warming. Paleoceanographic estimates of changes in variability under past climatic states have emerged as a powerful method to clarify the sensitivity of interannual variability to climate forcing. Several approaches have been developed to investigate interannual SST variability within and beyond the observational period, primarily using marine calcifiers that afford subannual‐resolution sampling plans. Amongst these approaches, geochemical variations in coral skeletons are particularly attractive for their near‐monthly, continuous sampling resolution, and capacity to focus on SST anomalies after removing an annual cycle calculated over many years (represented as geochemical oscillations). Here we briefly review the paleoceanographic pursuit of interannual variability. We additionally highlight recent research documented by Ong et al., (2022, https://doi.org/10.1029/2022PA004483) who demonstrate the utility of Sr/Ca variations in capturing SST variability using a difficult‐to‐sample meandroid coral species, Colpophyllia natans, which is widespread across the Caribbean region and can be used to generate records spanning multiple centuries.

Analysis of chlorophyll-a, sea surface temperature, and sea surface salinity in the Bay of Bengal

The waters of the Bay of Bengal (BoB) are influenced by the northeast monsoon (November-February) and the southwest monsoon (June-September). This study aims to determine the relationship between sea surface temperature (SST), sea surface salinity (SSS), and chlorophyll-a (Chl-a) during January 2021 in the BoB. The method used in this study is the method of correlation analysis, hypothesis testing, and analysis of variance using monthly average data for January 2021. The data comes from the Copernicus Marine Environment Monitoring Service (CMEMS) portal. Our analysis showed that high Chl-a was inversely related to low SST and SSS conditions and vice versa. This finding confirms the results of other previous studies. Medium and negative correlations occurred for the Chl-a - SST and Chl-a - SSS pairs. Meanwhile, the SST- SSS pair shows a strong and positive correlation. The hypothesis test shows that the conclusions drawn from these correlation relationships are acceptable. Furthermore, from the analysis of variance obtained, it was found that Chl-a had a significant effect on variations in SST and SSS, while SST had a significant effect on variations in SSS.

Sr/Ca-temperature calibration for the coral Montastraea cavernosa

The Sr/Ca ratio in coral skeletons is an important proxy for the reconstruction of sea surface temperatures (SST) of the environment and helps our knowledge about SST variability in the tropics. In the western tropical South Atlantic where the species Montastraea cavernosa is one of the most important reef-builders, only a few species have been evaluated as coral-based archives for environmental changes. Here we evaluate the Sr/Ca ratio recorded in the thecal wall and other skeletal structures of the species M. cavernosa and its implications for paleothermometry investigations. Sampling along the thecal wall generated a record of Sr/Ca ratios with well-defined annual cycles, but also with noisy intervals. A linear regression of the most recent 8 years of well-defined Sr/Ca ratios and SST results in the calibration equation Sr/Ca (mmol/mol) = −0.040 (±0.005) * SST (°C) + 10.15 (±0.15). This is the first calibration equation for this species. The skeletal elements of M. cavernosa were characterized by heterogeneous Sr/Ca ratios, with higher values for the columellae and septum, which could potentially generate a cold bias in reconstructed SST of up to 7.5 °C. The variability of Sr/Ca ratios in these structures overwhelms the annual seasonality of Sr/Ca ratios in the thecal wall, and the difference in Sr/Ca ratios observed from distinct skeletal structures may be related to biological or vital effects influencing the uptake of Sr into different coral structures. Furthermore, improving sampling techniques for M. cavernosa should be considered in future studies for the successful recovery of robust geochemical signals, eventually expanding the number of species used as natural archives in the western tropical South Atlantic.

Role of sea surface temperature variability on the risk of Canadian wheat, barley, and oat yields

Surface air temperature (SAT) and precipitation in Prairie (Western) and Maritime (Eastern) Canada are influenced by the El Niño Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO), respectively. However effects of ENSO and AMO on major crop yield in Canada is yet to be understood. Here we investigate the longest record (1908–2017) of wheat, barley, and oat yield as well as its associated risk with summer (May-September) ENSO and AMO interannual and multidecadal variability in Prairie and Maritime, respectively. We used generalized linear models with autocorrelative residuals to assess region- and crop-specific associations between ENSO, AMO, surface air temperatures, and precipitation on crop yield. After adjusting for covariates our models show that a positive phase of the AMO (in comparison to negative phase) significantly reduces the risk of Maritime crop yields by ~3–12%, with both extreme heat and wet precipitation found to be significant risk factors for reducing yields. Summer El Niño or La Niña was found to have a small, insignificant effect on yield in the Prairie region, with no effects found on crops in Maritimes. Therefore, analysis of Atlantic oceanic variability can offer insight into major crop yield variability in Maritime Canada.

Sensitivity simulation of sea surface temperature variability in coastal waters off East Africa in relation to the Indian Ocean Dipole

East African coastal waters in the tropical western Indian Ocean experience strong seasonality which varies yearly, leading to the establishment of a prominent interannual Indian Ocean Dipole (IOD). This has a significant influence on regional and global socio-economic, climatic and human development. Sea surface temperature (SST) variability in these waters and its association with ocean–atmosphere feedbacks and internal subsurface ocean dynamics in relation to the IOD is the subject of this study. The research used reference simulation accompanied with sensitivity simulations with forcings from higher frequency variabilities against climatological signals of ocean–atmosphere or internal subsurface ocean dynamics from 1980 to 2007. Wind forcing with higher-frequency variabilities was applied in all simulations. Cooling and warming during pure and positive IOD events leading El Niño events in the region is caused by a combination of both surface heat fluxes associated with ocean–atmosphere feedbacks, and internal subsurface ocean dynamics, from July and peaking in August and October, respectively. Such processes also dominate the warming (cooling) in the region during pure El Niño (La Niña) events from July to December (July to October) where the SST patterns extend southwards. The warmest (coolest) SST anomalies during positive (negative) IOD events co-occurring with El Niño (La Niña) events stay longer than other events, being characterised by bimodal peaking in August and December. Such SST patterns are significantly forced with ocean–atmosphere feedbacks that might be associated with Walker circulation driving links between the Indian and Pacific oceans; however, the peaking in August might be enhanced by small ocean dynamics off the Somali coast, probably owing to the existing upwelling systems during these conditions.