Sea Surface Temperature Conditions Research Articles

Understanding Balanophyllia regia Distribution in the Canary Islands: Effects of Environmental Factors and Methodologies for Future Monitoring

The future of marine ecosystems is at risk due to climate change and other human impacts. Specifically, due to ocean warming, some tropical species are expanding their populations while populations of temperate species are in regression, making the establishment of conservation measures imperative to maintain local biodiversity. In this study we establish a baseline on the distribution and abundance of the temperate coral Balanophyllia regia from the Canary Islands. We found that the main environmental factors determining B. regia’s distribution and abundance were sea surface temperature and hydrodynamic conditions. Areas under large wave action and colder environments enhanced this warm-temperate species’ development. Since its metabolic performance depends exclusively on the surrounding environment, we also propose a methodology to potentially monitor climate change on coastal habitats through this azooxanthellate calcified coral. Results of a tagging experiment showed that a concentration of 20 mg/mL of calcein during 6 h might be enough to in situ label polyps of B. regia without compromising corallite survival. Long-term monitoring of population abundances and growth rates of B. regia through calcein tagging will allow us to identify alterations in local ecosystems early and focus future conservation investments on the most vulnerable areas with higher ecological and economic value.

Using artificial neural networks and citizen science data to assess jellyfish presence along coastal areas

Abstract Jellyfish blooms along coastal areas can pose significant challenges for beach users and local authorities. Understanding the factors influencing jellyfish presence is crucial for effective management and mitigation strategies. In this study, citizen science data from the Andalusian coast (232 beaches, in 40 different localities) and machine learning techniques are used to investigate if the presence and absence of jellyfish along coastal areas can be predicted. A multi‐layer perceptron (MLP) neural network was employed to classify user comments regarding jellyfish presence or absence, achieving an accuracy of approximately 96%. The MLP model demonstrated robustness in handling non‐linear classification problems and noise, although it showed lower precision for predicting jellyfish presence, likely due to an imbalance in the dataset. Environmental data were also incorporated to characterise the influence of sea surface temperature, wind direction and wind speed on jellyfish distribution. The results align with previous studies, suggesting these environmental factors significantly impact jellyfish presence. Synthesis and applications. This research provides actionable recommendations for beach management. The implementation of continuous monitoring of sea surface temperature and wind conditions will enable more accurate predictions of jellyfish distribution. Adaptive management strategies that respond dynamically to environmental data will help mitigate the impact of jellyfish blooms on coastal tourism and public health.

Dynamics of Noctiluca scintillans blooms: A 20-year study in Jangmok Bay, Korea

This 20-year study (2001–2020) conducted in Jangmok Bay, Korea, assessed the intricate relationships between environmental factors and Noctiluca scintillans blooms. Granger causality tests and PCA analysis were used to assess the impact of sea surface temperature (SST), salinity, dissolved oxygen (DO) concentration, wind patterns, rainfall, and chlorophyll-a (Chl-a) concentration on bloom dynamics. The results revealed significant, albeit delayed, influences of these variables on bloom occurrence, with SST exhibiting a notable 2-month lag and salinity a 1-month lag in their impact. Additionally, the analysis highlighted the significant roles of phosphate, ammonium, and silicate, which influenced N. scintillans blooms with lags of 1 to 3 months. The PCA demonstrates how SST and wind speed during spring and summer, along with wind direction and salinity in winter, significantly impact N. scintillans blooms. We noted not only an increase in large-scale N. scintillans blooms but also a cyclical pattern of occurrence every 3 years. These findings underscore the synergistic effects of environmental factors, highlighting the complex interplay between SST, salinity, DO concentration, and weather conditions to influence bloom patterns. This research enhances our understanding of harmful algal blooms (HABs), emphasizing the importance of a comprehensive approach that considers multiple interconnected environmental variables for predicting and managing N. scintillans blooms.

Assessing the accuracy of MUR high resolution satellite sea surface temperature data

Marine bivalve mollusks are valuable proxies for El Niño-Southern Oscillation (ENSO) events in paleoclimate research, reflecting changes in sea surface temperature (SST) and other ambient marine conditions in their shell chemistry. However, the use of several Peruvian species of bivalves as paleoENSO proxies needs to be established by comparing their shells’ δ18O-derived SST records with instrumental SST measurements. Along the Peruvian coast, the limited spatial coverage of in-situ coastal monitoring stations hinders such comparisons. This study aims to assess the accuracy of the Multi-scale Ultra-high Resolution (MUR) satellite-derived SST dataset as an alternative source of SST information for paleoENSO studies in Peru, which could advance research on Peruvian bivalve species. This study compares MUR satellite data with in-situ measured SST from ten coastal monitoring stations operated by the Instituto del Mar del Perú (IMARPE). The correlation between the datasets is evaluated, and systematic and non-systematic variations are examined. Environmental factors that may impact the accuracy of satellite SST measurements, such as clouds and aerosols, are also investigated. Results show that MUR data generally correlate with overall trends in SST variability captured by in-situ measurements. However, there are regional variations in the accuracy of MUR data, with some areas showing consistent temperature offsets. Differences in measurement methodologies and environmental variables are explored as potential causes of variations between the datasets. Overall, the study demonstrates the potential of using high-resolution satellite SST data for assessing δ18O SST records from bivalves in locations without local SST records. It provides insights into the accuracy and limitations of using MUR data as an alternative source of SST information for paleoENSO studies in coastal Peru.

Contrasting temporal trends in low-level clouds and mid- and high-level clouds over the Indian Ocean in the last four decades (1979–2018)

Understanding the climatic trends in cloud fraction (f c ) and its drivers is critical in climate science. Here, we analyzed 40 years (1979–2018) of hourly f c data at 0.25° × 0.25° spatial scale from ERA5 to examine the trends in the 3D distribution of f c over the oceanic region adjacent to the Indian Subcontinent in view of its drivers. We found that the mid-level f c (MCF) and high-level f c (HCF) have increased by 0.05 and 0.05–0.12 fraction in the last four decades in this region. On the contrary, the low-level f c (LCF) decreased by 0.04 fraction, resulting in a net marginal increase in total f c . The observed contrasting trends in LCF, MCF and HCF are manifestations of the changes in sea surface temperature and meteorological conditions. Although LCF showed a regionally averaged declining trend, it has increased over the south-southwestern part of the domain. The increasing trend of MCF and HCF can be attributed to the increase in natural convection due to surface warming. Our results suggest that the observed contrasting trends might have resulted in positive radiative feedback on the Indian Ocean warming.

Impacts of the Mesoscale Ocean‐Atmosphere Coupling on the Peru‐Chile Ocean Dynamics: Impact of the Thermal Feedback

AbstractConsequences of the mesoscale Thermal FeedBack (TFB) on the ocean dynamics are studied in the South‐East Pacific (SEP) using a high‐resolution regional ocean–atmosphere coupled model. Three simulations are compared: the first one is a fully coupled simulation. In the second one, the TFB has been removed with an online smoothing of the Sea Surface Temperature (SST) conditions used by the atmosphere. In the third one, to disentangle the impact of the nearshore and the offshore TFB, the smoothing is only applied in the offshore region. In the SEP, the coastal upwelling cold tongue constitutes a permanent mesoscale SST pattern. We show that this SST pattern alters the coastal wind structure, reducing the coastal upwelling‐favorable wind intensity. So, the nearshore TFB reduces the coastal surface current and the vertical velocities. As a result, the Eddy Kinetic Energy (EKE) generation by baroclinic conversion is also weakened. In the offshore region, on the contrary, the oceanic mean state is not affected by the TFB and only the EKE is weakened. Composites above the coherent eddies show that the heat flux response to the mesoscale SST anomalies is responsible for the mesoscale activity weakening over the whole studied area. Although the wind response to the SST anomalies has a very weak mean impact on the EKE generation through wind work, we show that it strongly modifies the mean oceanic vertical velocity anomalies over the coherent eddies.

Evaluation of Sea Surface Temperature from the Satellite Observations and Model Output using In Situ Measurement dataset: Study area Panjang Island, Banten

Abstract Sea surface temperature (SST) is a crucial parameter in climate change studies, and it can be obtained from various sources, including in-situ measurements, satellite observations, reanalysis, and models. However, due to the limited availability of in-situ data, researchers often rely on satellite observations and models, all of which are susceptible to errors. This study aims to improve the accuracy of SST data from satellite observations and models by evaluating and calibration the data through comparison with in-situ SST data using time series analysis. The study areas are Panjang Island, Banten, with a period from April 15, 2022, to February 7, 2023. The data was collected from satellite (OISST V2.1), model (Hycom GOFS V3.0-3.1), and in-situ (loggers HOBO U-24 and TidBit V2.1). The results show that satellite-derived SST values perform better than the model based on higher satellite correlation coefficient values (r = 0.853) compared to the model (r = 0.685). In addition, satellite data also have lower error rate ( x ¯ b i a s = 0.445°C; σ bias = 0.304°C; RMSE = 0.538°C) than model ( x ¯ b i a s = 0.472°C; σ bias = 0.32°C; RMSE = 0.57°C). The variance tests show no significant difference for satellite (p-value = 0.785) and model (p-value = 0.346) data against in-situ data, while the mean tests reveal disparities (p-value < 0.001). The calibration process reduces error values for both satellite ( x ¯ b i a s = 0.276°C; σ bias = 0.225°C; RMSE = 0.356°C) and model data ( x ¯ b i a s = 0.398°C; σ bias = 0.298°C; RMSE = 0.397°C), but the correlation coefficients remain stable at 0.853 (satellite) and 0.685 (model). In conclusion, satellite observations provide a more precise picture of the SST conditions on Panjang Island, Banten and the calibration process can improve the quality of satellite model data.

Population connectivity of small yellow croaker (Larmichthys polyactis) in the southern Yellow Sea: Implications from multiple otolith-based approaches

Connectivity is a fundamental aspect governing the viability of marine species populations, particularly during their early life stage. However, a dearth of comprehensive studies exists regarding connectivity patterns in Larmichthys polyactis within the southern Yellow Sea region. To address this gap, we conducted a thorough investigation into the population connectivity of L. polyactis collected from Haizhou Bay (HZB) and Lvsi (LS) fishing grounds, employing a suite of otolith-based methodologies. Initially, our analysis of otolith microstructure revealed a notable incubation peak occurring between early and mid-April for juvenile L. polyactis sampled in HZB, despite the sea surface temperature (SST) during that period not aligning with the known spawning requirements of L. polyactis. By juxtaposing the spawning period and associated SST conditions of L. polyactis across different fishing grounds, we deduced a high likelihood that the HZB samples originated from the LS. Subsequently, we investigated the stable isotope ratios (δ13C and δ18O) of L. polyactis collected in HZB, LS, and offshore locations, focusing on the core zone indicative of the early life stage. Statistical analysis using Dunn’s multiple comparison test revealed that no significant disparity in otolith δ13C and δ18O values between HZB and LS samples (P > 0.01). However, these values were notably lower than those observed I n offshore samples (P < 0.01). Furthermore, through otolith morphological analysis, we identified two distinct aggregations within the HZB samples, one aligning with the entirety of the LS samples and another representing the remaining HZB sample subset. This finding provides additional support for the population connectivity between HZB and LS stocks. Drawing upon these findings, we posit the existence of a a mixed population of L. polyactis within HZB, likely resulting from the transportation of eggs or larvae originating from LS to HZB via prevailing northward currents. An enhanced understanding of connectivity dynamics among L. polyactis holds significant implications for the formulation of effective management strategies aimed at bolstering stock recovery efforts.

Analysis of Upwelling Parameters when the El Nino Southern Oscillation (ENSO) Occurred in the Halmahera Sea

Upwelling events that occur in the Halmahera Sea are influenced by the El Nino Southern Oscillation (ENSO). Upwelling can cause sea surface temperatures to be lower than normal, affecting the potential of fishery resources in the region. The purpose of this study was to determine the conditions of sea surface temperature, chlorophyll-a content, salinity, and upwelling conditions when viewed from the parameters of chlorophyll-α content and sea surface temperature when El Nino was strong, El Nino was weak, La Nina was strong, and La Nina weak and in normal conditions in the Halmahera Sea region. The data used in this study include the Oceanic Nino Index, sea surface temperature, salinity, and chlorophyll-α content during the 2010–2019 period. A quantitative descriptive research type is used by filtering ENSO data to determine when ENSO occurred, then visualizing the data in each parameter and analyzing it. The results of this study show that upwelling is known to occur in the northern to western parts of the Halmahera Sea. When the El Nino phase is vital, the upwelling parameter changes, the sea surface temperature decreases to 27.1⁰C, the chlorophyll-α content increases to 0.70 mg/m3 compared to the normal phase, and the upwelling intensity changes

Thermal vulnerability of sea turtle foraging grounds around the globe

Anticipating and mitigating the impacts of climate change on biodiversity requires a comprehensive understanding on key habitats utilized by species. Yet, such information for high mobile marine megafauna species remains limited. Here, we compile a global database comprising published satellite tracking data (n = 1035 individuals) to spatially delineate foraging grounds for seven sea turtle species and assess their thermal stability. We identified 133 foraging areas distributed around the globe, of which only 2% of the total surface is enclosed within an existing protected area. One-third of the total coverage of foraging hotspots is situated in high seas, where conservation focus is often neglected. Our analyses revealed that more than two-thirds of these vital marine habitats will experience new sea surface temperature (SST) conditions by 2100, exposing sea turtles to potential thermal risks. Our findings underline the importance of global ocean conservation efforts, which can meet climate challenges even in remote environments.

Causal oceanic feedbacks onto the winter NAO

Of the climate variability patterns that influence the weather in the North Atlantic region in winter, the North Atlantic Oscillation (NAO) is the most dominant. The effects of the NAO span from cold air outbreaks to unseasonably warm conditions and unusual precipitation, with significant impacts on human activities and ecosystems. While a connection between the NAO and antecedent sea surface temperature (SST) conditions has been recognised for decades, the precise causal interaction between the ocean and the atmosphere remains enigmatic. In this study we uncover a robust statistical relationship between North Atlantic SSTs in November and the NAO throughout the subsequent winter in the extended ERA5 reanalysis back to 1940. We apply a well-established causal inference technique called mediation analysis, commonly used in social science and now adopted in climate research. This analysis highlights the roles of low-level baroclinicity, latent heat fluxes, and latent heat release in mediating the effect of November SSTs on the NAO in January and February. It is important to recognise that these mediators are interrelated. Moreover, our analysis reveals bidirectional relationships, where the NAO reciprocally mediates the effects of the November SSTs on these variables. This is evidence of a complex web of feedback mechanisms which collectively contribute to the response of the winter NAO to late autumn/early winter SSTs.

Correction: Spatial variation and antecedent sea surface temperature conditions influence Hawaiian intertidal community structure

Correction: Spatial variation and antecedent sea surface temperature conditions influence Hawaiian intertidal community structure

Monitoring invasive macroalgae in southern Portugal: drivers and citizen science contribution

Under certain environmental and oceanographic conditions, macroalgae can overgrow and accumulate in massive quantities on beaches, causing serious ecological and economic impacts. To address this problem, a citizen science monitoring platform was created to determine the spatial and temporal distribution of macroalgae accumulations along the beaches of Algarve in southern Portugal, with the aim to assess the extent of beach-cast events and their relationship with abiotic factors. A Redundancy Analysis (RDA) and a permutational analysis of variance (PERMANOVA) were carried out to explore the relationship between macroalgae accumulation level and the abiotic variables: sea surface temperature, wind speed, wind direction, currents, maximum sea level, significant wave height, salinity, nitrate, ammonium, phosphate, precipitation and radiation. The citizen science campaign showed great participation, resulting in 404 submissions between July 2021 and September 2023. The campaign revealed that three species of macroalgae accumulated on the beaches of Algarve, Ulva sp. (with the presence of Ectocarpales and Dyctiotales) along the sandy eastern coast, and the invasive species Asparagopsis armata and Rugulopteryx okamurae in the rocky central and western beaches, respectively. The accumulations of R. okamurae increased from 2021 to 2023, were registered throughout the year and were more abundant than those of Ulva sp. and A. armata, which were only observed in spring and summer. The highest levels of R. okamurae beach-cast depositions were related to strong wave conditions, and high sea surface temperature and salinity. The accumulation of Ulva sp. was related to high sea surface temperature and salinity whereas A. armata was also correlated with winds parallel to the shore (NW-W). PERMANOVA analysis revealed that sea surface temperature and wave conditions had a significant effect on the overall abundance of macroalgae beach-cast accumulations. Overall, our citizen science campaign effectively involved the public, leading to the collection of important data on monitoring macroalgae accumulations. Through these findings, we were able to pinpoint the environmental, atmospheric, and hydrodynamic factors that contribute to their development, movement, and buildup along the Algarve coastlines.

Connecting North Atlantic SST Variability to European Heat Events over the Past Decades

The occurrence of European heat events has increased during the last two decades. European heat events are responsible for social, economic and environmental damage and are projected to increase in magnitude, frequency and duration under global warming, strengthening the interest about the contribution of different mechanisms. Using the ERA5 reanalysis product, we go beyond case studies relating European heat events with cold North Atlantic sea surface temperatures (SSTs), and perform a systematic approach with a composite analysis to investigate the link between North Atlantic SSTs in a domain south of Greenland and the 2m air temperature (T2m) over central Europe. Composites of different North Atlantic SST states show that events with a negative tendency of North Atlantic SSTs are often followed by positive European T2m anomalies during summers when the North Atlantic SSTs are persistently low for several months. Enhanced lower–tropospheric baroclinicity in the North Atlantic is followed during these events by a slantwise ascent and an enhanced upper–tropospheric waveguide, promoting a downstream development of an European ridge. A combination of a wave number 3 pattern and regionally confined Rossby wave activity contribute to a trough–ridge pattern in the North Atlantic–European sector. A composite of European heat events further confirms the lagged statistical relationship between cold North Atlantic SSTs with a negative tendency and positive European T2m anomalies. A negative tendency of North Atlantic SSTs precedes 15 of 18 European heat events, and cold North Atlantic SST conditions are present during 14 of 18 European heat events.

Convection-permitting simulations reveal expanded rainfall extremes of tropical cyclones affecting South Korea due to anthropogenic warming

AbstractUnderstanding how global warming affects tropical cyclone (TC) intensity and precipitation for target regions is essential to preparing for associated damages but detailed processes remain uncertain. This study provides the first quantification of anthropogenic influences on TC characteristics affecting South Korea using convection-permitting model (CPM) simulations (3 km resolution). For the observed four recent TCs that strongly affected South Korea, CPM simulations were performed under current (ALL) and counterfactual conditions without human influences (NAT). The observed sea surface temperature and lateral boundary conditions were used for ALL while changes attributable to human influences (estimated using CMIP6 multimodel simulations) were removed from observed boundary conditions for NAT runs. ALL experiments captured the observed TC intensity and precipitation reasonably. After removing human influences, TC intensity and precipitation were reduced in NAT experiments. Importantly, areas with extreme precipitation (i.e., having precipitation larger than 150 mm) were found to expand by 16–37% in ALL compared to NAT, which was induced by an enhanced upward motion near the TC core and an increase of background water vapor in line with warming. Further, the role of increased moisture was found to become important as TC moves to mid-latitudes. This study provides valuable insights into how greenhouse warming can intensify TC-induced extreme precipitation over East Asia.

Effect of global and regional SST biases on the East Asian Summer Monsoon in the MetUM GA7 and GC3 configurations

Climate-length experiments of the Met Office Unified Model Global Atmosphere 7.0 (GA7) and Global Coupled 3.0 (GC3) configurations are evaluated against observations and reanalyses for the simulation of the East Asian summer monsoon (EASM). The results show systematic model biases, such as overestimated rainfall over southern China and underestimated rainfall over northern China, suggesting a monsoon that does not penetrate northward enough. We evaluate the effects on the EASM of regional errors in sea-surface temperature (SST) conditions in three regions: the Pacific, the Indian, and the Atlantic Oceans. The global SST biases in GC3 configuration substantially shift the EASM seasonal cycle: a late northward progression of the EASM in the early/mid-monsoon season, and an early retreat of the monsoon that also reduces rainfall over most of northern China. The EASM seasonal rainfall bias in the EASM region is linked to changes in the locations and strength of the western North Pacific subtropical high, which is associated with biases in local evaporation and moisture transport towards South China. GC3 biases in the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) teleconnection pathways also influence the EASM biases. GC3 biases weaken the ENSO teleconnection to the EASM and cause a strong dry bias in southeast China during developing El Niño.

Comparison of the opposite behaviours of Korean heatwaves with extreme hot sea surface temperatures in August 2016 and 2022

AbstractIn South Korea, an unprecedented heatwave occurred in August 2016. That year, sea surface temperature (SST) in the Korean marginal seas (KMS) was remarkably higher than that in climatology, and upper‐level anticyclonic circulations favoured this heatwave. More recently, similar conditions that can expect the frequent occurrence of heatwaves prevailed in August 2022. However, the opposite extreme phenomenon, heatwave days below climatology, occurred with the emergence of a stationary rainband in South Korea. This study aims to understand the two different behaviours of heatwaves in Korea under the same hot SST conditions in the KMS. The most pronounced difference between these two extreme cases is the existence of moisture flux related to the western North Pacific summer monsoon (WNPSM). Although the WNPSM is not generally highly correlated with temperature and precipitation in Korea, their relationship is particularly strong when hot SST conditions develop in the KMS. This SST condition, combined with the WNPSM, plays a role in determining this anomalous moisture flux in Korea. Enough tropical moisture flux occurred to build a stationary front with declining heatwave days during August 2022. In contrast, extremely dry and hot weather was more likely in 2016 due to inactive moisture fluxes from the western North Pacific.

Holocene millennial-scale variability of coastal environments on the southern coast of Korea and its controlling factors

AbstractCoastal evolution is influenced by past sea-level changes and resultant shifts from fluvial- to marine-dominant environments and the accompanying significant geochemical and isotopic changes in the water mass and sediments. We investigated the elemental and isotopic features of coastal sedimentary cores (27 m in length) from a small paleo-bay located on the southern coast of Korea to determine such geochemical variability and specify past changes in the bay environment and anoxic conditions and possible links to past climate changes. We analyzed total organic carbon (TOC), total sulfur (TS), their isotopes (δ13CTOC and δ34STS), and pyrite. The δ13CTOC values ranging from −25 to −19‰ (a proxy for terrestrial influence) were lower than average (−22.5‰) before 8300 cal yr BP and since 500 cal yr BP, while the intervening Early to Late Holocene showed higher δ13CTOC values, indicating a shallow coastal environment. The δ34STS values fluctuating between −35 and +5‰ resembled sedimentation rate change. Based on the changes in the ratios of TOC to TS (C/S ratios), sedimentation rate, and δ34STS, we found five possible periods with higher salinity and intensified anoxic conditions at millennial timescales: 8900–8200, 7950–6500, 5200–4300, 3500–2600, and 2000–1100 cal yr BP. These intensified anoxic conditions seem to have been influenced by increased air temperature and sea-surface temperature conditions, which could have intensified the intensity of thermal stratification (less ventilation and mixing) between surface and bottom waters and resultant anoxic conditions.

Interannual Variations in the Intraseasonal Variability of Spring Precipitation over Southern China and the Possible Mechanisms

Abstract This study first investigates the interannual variations in spring precipitation intraseasonal variability over southern China (SC). The results show that SC spring precipitation exhibits distinct intraseasonal variations with a period of 7–25 days. The first mode of 7–25-day precipitation intraseasonal variability (PIV) displays a monopole pattern over SC, and the PIV magnitude is largely determined by the upward motion intensity during intraseasonal precipitation events. Further analysis suggests that two atmospheric wave trains are observed during intraseasonal precipitation events, which propagate eastward from the North Atlantic along the northern and southern paths. In strong PIV years, the two wave trains can propagate to East Asia and show coordinated influences. The resultant low pressure to the west of SC causes strong upward motion and PIV over SC by bringing strong zonal vorticity and meridional temperature advection. In weak PIV years, the southern wave train can only propagate to the Bay of Bengal; therefore, the northern wave train plays a major role. The resultant low pressure is now over the upper to middle reaches of the Yangtze River, which causes relatively weak upward motion and PIV over SC by bringing weak meridional vorticity and temperature advection. Further analysis indicates that the sea surface temperature (SST) condition over the tropical Indian Ocean and the South China Sea is essential for southern wave train propagation. The warming SST over the regions can intensify westerlies to its north and consequently favors the propagation of the southern wave train to SC, eventually contributing to strong PIV over SC.

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.