Sea Surface Temperature Changes Research Articles

Intercomparison of satellite-derived SST with logger data in the Caribbean—Implications for coral reef monitoring

Since the early 1980s measurements of Sea Surface Temperature (SST) derived from satellite-borne instruments have provided a wide range of global gridded products documenting changes in SST. However, there are many sources of uncertainty in these records and significant differences exist among them. One use of these products is identification of coral bleaching events, and the predictions of the impact of future warming on coral reefs. This relies on an understanding of how temperatures near reefs as recorded by SST products differ from the in-situ SST experienced by the corals. This difference is a combination of real spatio-temporal variations, inadequate in product resolution and errors in the products. This paper investigates the relationship between the local temperature measured in-situ by loggers at coral sites in the western tropical Atlantic and two high resolution satellite SST products. Using differences among ESA SST CCI v2.1 (CCI analysis SST), NOAA CoralTemp SST products and in-situ logger data from coral reefs, an assessment of the satellite products with focus on coral reef monitoring is carried out. Discrepancies between the two products can be large, especially in coastal areas and for the warmest and coldest months when there is a particular risk of bleaching. By comparison to the stable CCI analysis SST product, CoralTemp was found to overestimate the rise in SST by as much as 0.20°C per decade. In almost all cases SSTs from CCI analysis SST were more consistent with temperatures measured near the corals than those from CoralTemp.

Unravelling the mechanism of transient coastal upwelling in the southeastern Arabian Sea triggered by Cyclone Michaung

Abstract This study investigates the impact of Cyclone Michaung on coastal dynamics and biological changes in the southeastern Arabian Sea (SEAS). Utilizing data from a moored autonomous buoy, the water quality nowcasting system (WQNS), and multi-satellite datasets, the research documents significant changes in sea surface temperature (SST), salinity, and dissolved oxygen (DO) concentrations were driven by cyclone-induced upwelling and downwelling processes in the SEAS. The findings revealed that the passage of Cyclone Michaung led to a transient coastal upwelling event along the southwest coast of India (SWCI), marked by a notable decrease in SST and DO and an increase in salinity and chlorophyll-a concentrations, indicating enhanced biological production. The wind stress strengthening and changing wind pattern, almost parallel to the coast, initiated this process through wind-induced Ekman pumping, which uplifted the biological activity in the region.

Oceanic Tunnel Controls of Eastern Equatorial Pacific Surface Temperature and Productivity Over the Past 3.6 Myr

AbstractRobust modern gradients in sea surface temperature (SST) and biological productivity across the eastern equatorial Pacific (EEP) Ocean between 80° and 140°W derive from vigorous upwelling of cold and nutrient‐rich waters. However, during the mid‐Pliocene warm period (3.0–3.3 Ma), the zonal SST gradient within the EEP was reduced to <0.5°C while the productivity gradient remained as strong if not stronger than modern. We consider the oceanographic mechanisms and external climate forcings responsible for the evolution of the SST‐productivity coupling. We synthesize existing records and present new reconstructions of alkenone biomarker SST and productivity from four EEP sites. The progressive SST gradient strengthening over the Plio‐Pleistocene contrasted with the stronger Late Pliocene surface productivity gradient relative to modern. Dominance of the oceanic tunnel over surface forcings best explains these observations: SST changes reflect extratropical water masses cooling toward the present while productivity proxies suggest these waters became less nutrient‐rich.

Comparing the Atmospheric Responses to Reduced Arctic Sea Ice, a Warmer Ocean, and Increased CO2 and Their Contributions to Projected Change at 2°C Global Warming

Abstract We consider the combined and individual influences of Arctic sea ice loss, sea surface temperature (SST) warming, and the direct radiative effect of increased CO2 on the Northern Hemispheric climate. The surface climate (e.g., temperature and precipitation) and atmospheric circulation responses (e.g., sea level pressure and wind) to these drivers are quantified using simulations from the Polar Amplification Model Intercomparison Project (for sea ice loss and SST warming) and the Cloud Feedback Model Intercomparison Project (for increased CO2). We verify the linear additivity of the PAMIP-derived winter responses to sea ice loss and SST change. The responses to SST change are of greater magnitude than that due to sea ice loss or due to CO2 direct radiative forcing in most seasons and regions, excluding the Arctic. Notably, however, sea ice loss is at least as important as SST change for the winter atmospheric circulation response over the North Atlantic and Siberia. The dynamical responses to sea ice loss and SST change oppose each other in many regions in winter, while the responses to SST and CO2 direct radiative forcing are often opposing in summer. Such opposing responses are less evident for the thermodynamical response. The sum of all three responses reproduces well the spatial patterns of change at 2°C global warming in winter and autumn in phase 6 of the Coupled Model Intercomparison Project projections but overestimates their magnitude.

Dropsonde Observations of the Stable Marine Boundary Layer beneath Atmospheric Rivers

Abstract An important source of errors in predicting landfalling atmospheric rivers (ARs) and their associated extreme precipitation and streamflow are inaccuracies in model initial conditions in ARs offshore. These inaccuracies are particularly evident in the marine boundary layer (MBL) where the tendency of ARs to transport warm air poleward over progressively cooler sea surface temperatures (SSTs) generates a stable MBL (SMBL). The SMBL’s vertical structure and key modulating processes are documented using >1000 dropsondes along 99 transects of ARs from the AR reconnaissance and CalWater field campaigns. The SMBL depth, modulated by sensible heat loss to the ocean, is typically 300–800 m in the AR core, with vertical wind shears ranging from 5 to 50 m s−1 km−1, representing a highly variable decoupling of the AR aloft from conditions at the ocean surface. Simulated backward air parcel trajectories originating from dropsonde locations within the AR core are used to calculate the 24-h change in SST experienced by an air parcel (DSST24) beneath each AR. The DSST24 varies from −13° to +2°C and is directly related to the strength of the AR and its orientation relative to the SST gradient. The DSST24, therefore, distinguishes weak and strong decoupling regimes (WDR and SDR). In SDR cases, relative to WDR cases, the SMBL is characterized by greater sensible heat loss to the ocean, as well as stronger static stability, vertical wind shear, low-level jet, and horizontal water vapor transport. In SDR cases, the SMBL is deeper in the core than in adjacent warm and cold sectors.

Modulation in Teleconnections of the El Nino Southern Oscillation by Atlantic Multidecadal Sea Surface Temperature Variability

AbstractThis manuscript uses idealized AGCM experiments to explore impacts of observed decadal Atlantic sea surface temperature (SST) changes on El Nino Southern Oscillation teleconnections. Significant regional changes are observed in numerous locations (e.g., Indo‐Pacific and Central Africa) due to the addition of the AMV anomalies. In some regions the teleconnection impacts of AMV forcing appeared to scale with the magnitude of the AMV forcing. However, the AMV induced modulation of temperature and precipitation teleconnections is regionally specific with changes in magnitude, statistical strength, and spatial connection dependent on region. These ENSO teleconnection changes were found to be asymmetric between AMV phases, with negative anomalies appearing to have a larger effect. We hypothesize these changes may be underpinned by a AMV induced modulation and migration of ENSO's equatorial precipitation response.

Near-Inertial Oscillations Induced by Winter Monsoon Onset in the Southwest Taiwan Strait

The near-inertial motion in ocean surface currents directly reflects the energy transported by wind towards the surface layer, playing an important role in climate regulation and energy balance. Previous studies have mainly focused on near inertial oscillations (NIOs) induced by tropical cyclones in the Taiwan Strait, with few reports on near inertial oscillations induced by monsoon onset. Using high-frequency radar observations, we detected an amplification of NIOs induced by the winter monsoon onset. While not as strong as NIOs induced by tropical cyclones, the near-inertial current (NIC) induced by winter monsoon onset in the Taiwan Strait has peak speeds reaching up to 5.2 cm/s and explaining up to 0.7% of non-tidal variance. This study presents observational results of NIOs during three monsoon onset events, and analyzes the impact of winds and temperature changes on NIOs. Temporal and spectral analysis reveals that the monsoon onset is the primary driver behind the formation of NIOs. Results indicate that near-inertial kinetic energy is relatively lower in shallower waters, such as the Taiwan Bank, compared to deeper regions. Furthermore, by integrating the air and sea surface temperature from reanalysis products, we have examined the abrupt changes in sea surface temperature (SST) before and after monsoon onset and their correlation with NIOs. The findings suggest that temperature falling favors the intensification of NICs during monsoon onset, and a lack of significant SST changes precludes the triggering of notable NICs. These insights enhance our understanding of the mechanisms driving NIOs and their roles in seawater mixing.

Interhemispheric synchrony of Mid-Late Holocene SST in the Indo-Pacific warm pool linked to upper water column dynamics

The sea surface temperature (SST) of the Indo-Pacific warm pool (IPWP) plays a crucial role in global climate system. Despite its importance, knowledge of its SST changes over century to millennial timescales remains limited and controversial, hindering our comprehensive understanding of climate change mechanisms. Our study bridges this gap with a novel SST reconstruction spanning approximately 7000 years, derived by aggregating 75 coral Sr/Ca-SST records from the South China Sea. These records reveal a notable synchronization in SST variations with foraminiferal reconstructions across the IPWP, reflecting a prevalent pattern of interhemispheric cooling and multi-century variability in the IPWP during the Mid-Late Holocene. Further analysis reveals that these (sub)millennial SST variations are closely linked to subsurface water temperature and ocean heat content (OHC) changes, supporting the theory that the release of deeper OHC acted as a heat source for low-latitude processes during the Holocene.

Multi-proxy reconstructions of paleotemperature in the southern South China Sea since the last deglaciation

The accuracy of paleothermometers is a prerequisite for understanding the past sea surface temperature (SST) changes in the tropical seas. Here, we analyzed the SST estimates reconstructed by four lipid proxies with common linear and newly advanced models in parallel in a sediment core collected from the southern South China Sea (SCS). After excluding the impact of terrestrial input, all of the four proxies-inferred SSTs displayed a gradually warming pattern since 18.3 ka. Our long-chain alkenones-derived annual SST at seawater depth of 0–30 m (SST 0–30 m) record closely matched the regional synthetic SST record from the entire southern SCS, corresponding to high-latitude climate events during the deglaciation. The temperatures reconstructed by long-chain diols (LCDs) showed an upper limit of 27 °C, and we thus proposed that they reflected the optimal survival temperature for organisms producing LCDs when SST was higher than 27 °C. Isoprenoid and hydroxy glycerol dialkyl glycerol tetraethers (iGDGTs and OH-GDGTs)-derived temperatures likely reflected the subsurface temperature (subT) at seawater depth of 30–125 m and SST towards the warm season in the tropical sea, respectively.

Regionally Coupled Climate Model ROM Projects More Plausible Precipitation Change Over Central Equatorial Africa

AbstractUnraveling plausible future rainfall change (ΔPr) patterns is crucial for tailoring societies' responses to climate change‐induced hazards. This study compares rainfall projections from the regionally coupled ocean model (ROM) and its atmospheric component, the regional atmospheric model REMO, over Central Equatorial Africa (CEA). Both models are forced by the Earth system model MPI‐ESM‐LR following the Representative Concentration Pathway 8.5. Results reveal increased rainfall across most of CEA, with ROM projecting more widespread and intensified wetting than REMO, although REMO produces more precipitation under future conditions, underscoring the influence of historical biases on REMO's projection. Examining processes underpinning changes unveils strong controls of sea and land surface temperature changes in ΔPr differences between the two models. Specifically, ROM mitigates warming more over the Atlantic than over CEA landmass compared to REMO, inducing enhancement of the Congo Basin cell and increased precipitable water content through specific humidity, affecting deep convection. Both models project enhanced Sahel and Kalahari thermal lows, with ROM better depicting the Kalahari low's warmer nature than the Sahel low. The resulting temperature gradients strengthen the northern and southern shallow meridional Hadley overturning circulation. ROM simulates the wetter conditions than REMO, attributed to its weaker northern Hadley Cell, which restricts the likelihood of northward moisture divergence toward the Sahel. Additionally, differences in mid‐tropospheric moisture convergence differentiate between ROM and REMO's wetness relative to the historical period and under future conditions. ROM projections are more plausible, in association with the reliability of its added value under the historical climate and mechanisms underlying Δpr.

The West Pacific Teleconnection Drives the Interannual Variability of Autumn Wildfire Weather in the Western United States After 2000

AbstractWildfires pose a significant threat to human society as severe natural disasters. The western United States (US) is one hotspot that has experienced dramatic influences from autumn wildfires especially after 2000, but what has caused its year‐to‐year variations remains poorly understood. By analyzing observational and atmospheric reanalysis datasets, we found that the West Pacific (WP) pattern centered in the western North Pacific acted as a major climatic factor to the post‐2000 autumn wildfire activity by inducing anomalous high pressure over the western US via teleconnections with increased surface temperature, decreased precipitation, and reduced relative humidity. The WP pattern explains about one‐third of the post‐2000 years‐to‐year variance of the western US autumn wildfires. These effects were found to be much weaker in the 1980–1990s, as the active region of WP‐associated high pressure was confined to the eastern North Pacific. Such eastward shift of the WP teleconnection pattern and its resultant, enhanced influence on the weather conditions of western US autumn wildfire after 2000 are also captured by the sea surface temperature (SST)‐forced atmospheric model simulations with the Community Atmosphere Model version 6 (CAM6). The CAM6 ensemble‐mean changes in the WP teleconnection pattern at 2000 is about half of the observed changes, which implies that external radiative forcing and/or SST changes have played an important role in the WP pattern shift. Our results highlight a pressing need to consider the joint impacts of atmospheric internal variability and externally forced climate changes when studying the interannual variations of wildfire activity.

Influence of Spawning and Nursery Ground Environmental Changes on Walleye Pollock Catches Along the Eastern Coasts of Korea and Japan After the Late-1980s Climate Regime Shift

The eastern coasts of Korea (ECK) and Japan (ECJ) are located at the southernmost limit of walleye pollock distribution in the Northwest Pacific. Following the climate regime shift (CRS) in the late 1980s, pollock catches in these regions have declined sharply, with different trends emerging. This study examined the relationship between environmental factors, such as sea surface temperature (SST) and habitat suitability, and changes in pollock catches from the late 1980s to 2022. From the late 1980s to the late 1990s, El Niño and positive Pacific decadal oscillation (PDO) phases dominated, increasing SST in the ECK and ECJ habitats and rapidly decreasing catches. Although spawning grounds (SGs) have maintained high habitat suitability, nursery ground (NG) suitability has declined. From the late 1990s to 2022, La Niña and negative PDO phases prevailed, with SST continuing to rise along the ECK, further reducing catches. SG suitability remained high, but NG suitability declined. Along the ECJ, SST decreased after the late-1990s CRS, stabilizing catches. After the mid-2010s, the SST increased along the ECJ, reducing pollock catches, although SG suitability remained high. This study elucidates SST changes during early life stages and their effects on pollock catch, habitat, and resources in future marine environments.

Stability and reliability of regional cumulative impact mapping: A Canadian Pacific case study

Cumulative impact mapping is a commonly applied spatial representation of the impacts of human activities on the ocean. This spatial model has been applied at varying scales around the world, in part due to its ability to visually communicate complicated information in a simple way. The application of the model to decision-making processes requires an understanding of the reliability and stability of its outputs. This paper represents both an updated regional application in Pacific Canada and an evaluation of the tool over two iterations, 2015 and 2023. The regional application utilised higher model resolution and new and improved data inputs including 38 habitats and 46 activities across five sectors. High impact hotspots were found around major population centres and ports, as well as in fishing and shipping areas along the continental shelf. Commercial fishing, shipping, and climate change (sea surface temperature change) remained the major drivers of cumulative impacts in the region, and cumulative impacts per unit area continued to be highest in kelp and seagrass. Results suggest evidence of decreased impacts where improved protection for sponge reefs were implemented but show an overall increase in cumulative impacts for the region. Results showed consistency and reliability in the location of cumulative impact hotspots. Refinements in data quality and resolution of spatial data inputs contributed towards increasing the spatial precision of hot spot areas identified. Confidence in the cumulative impact mapping outputs and applications for marine spatial planning, marine protected area designation and management, research, and decision support are discussed.

Synergistic Impact of Diurnal Warm Layers and Inertial Wave Mixing on Sea Surface Temperature Warming and Upper Ocean Stratification

AbstractWe study two sea surface temperature (SST) warming events and upper ocean stratification changes in the northern South China Sea in 2022 using data from an EM‐APEX float and satellite observations. The diurnal warm layers (DWLs) and the increasing buoyancy frequency N2 above the top of the thermocline can restrict the penetration depth of nighttime convection and wind‐driven mixing, which prevents cooler water from mixing upward, allowing solar heating to increase the SST by more than 1°C in a few days. The stratification budget approach is used to reproduce observations below 40 m despite some uncertainties in estimating variables such as horizontal gradient. After the first SST warming event, the stratification changes in the subsurface layers constituted by an increase in N2 above 70 m and a decrease below this depth can be attributed to the combined effects of turbulent diffusion and vertical advection rather than to horizontal advection or penetrative solar radiation. This ocean interior mixing is likely caused by the shear of near‐inertial waves at ∼50 m, when the nighttime convection could not penetrate through the DWL's base around 20 m. The stratification budget approach fails to simulate the changes above 40 m after the second SST warming event partly due to the presence of a near‐surface freshwater layer. Our observations offer insights into the effect of inertial wave‐induced mixing in the ocean interior when near‐surface stratified layers are present, which can lead to changes in upper ocean stratification and SST.

Global climate-driven sea surface temperature and chlorophyll dynamics

Herein we study long-term changes in global sea surface temperature (SST) and chlorophyll-a concentration (CHL) in order to evaluate possible effects of climate change on the global marine ecosystems. Our approach is to analyze multi-model ensemble-means from global numerical-simulations available through the Coupled Model Intercomparison Project Phase 6 (CMIP6). A 250-year span consisting of the 1850–2014 historical period and the 2015–2099 climate-change projection was considered, where the Shared Socioeconomic Pathways (SSPs) 2.45 and 5.85 were selected as the projected climate-change scenarios. In the historical period, global linear trends show an SST increasing at 0.0024 °C year-1 and a CHL decreasing at −2.35x10-5 mg m-3 year-1, but by the last years (1985–2014) these changes become more abrupt: SST rising at 0.0146 °C year-1 and CHL declining at −1.49x10-4 mg m-3 year-1. During the intense climate-change scenario (SSP-5.85), SST increases at 0.0341 °C year-1 and CHL decreases at −0.0002 mg m-3 year-1, but in the last years (2070–2099) the warming is stronger (0.045 °C year-1) and the CHL decline is weaker (−0.0001 mg m-3 year-1). Additionally, Empirical Orthogonal Function (EOF) and dual Self-Organizing Maps (SOM) analyses on the model-data ensembles show: 1) significant correlations between SST and CHL patterns and climate teleconnection indices, 2) contracting polar and high latitude seascapes, 3) rising SST range (both high and low temperatures), 4) declining CHL in warming tropical seascapes, and 5) global expansion of low CHL levels. On the other hand, recent (2022–2023) global observed-SST anomalies mirror end-of-century projections, with extreme anomalies in tropical and subtropical regions and significant changes in near-polar regions. Thus, our findings emphasize the need to curb fossil fuel emissions in order to avoid irreparable consequences for the marine environment.

Nonlinear Radiative Response to Patterned Global Warming due to Convection Aggregation and Nonlinear Tropical Dynamics

Abstract Climate responses to global warming exhibit large dependence on the spatial pattern of sea surface temperature (SST) changes. A Green’s function (GF) approach—predicting the global climate response to a complex SST pattern change as the linear superposition of the response to finite-area SST perturbations evaluated in isolation—has been used to systematically evaluate and understand the top of atmosphere (TOA) radiation response to patterned warming. However, in general, the linear GF approach fails for TOA radiation reconstruction under future global warming scenarios in coupled models. Here, we show that the linear superposition of global mean TOA radiation responses to large SST warming perturbations at multiple patches (the GF approach prediction) overestimates the actual response to simultaneous multipatch perturbation. This is because the linear superposition overestimates tropical large-scale convection aggregation strengthening upon localized heating that enhances longwave radiative cooling, which is further explained by the overestimation of circulation response and associated horizontal water vapor transport. The nonadditivity of TOA radiation response is caused by the nonadditivity of convection aggregation, ultimately rooted in nonlinear tropical dynamics. We also demonstrate that the prediction error of the GF approach grows with decreasing patch size (equivalently, increasing patch number). We conclude that using the GF approach to predict future climate change could overestimate longwave radiative cooling and underestimate (effective) climate sensitivity. Numerical experiments may be used to identify specific perturbation patterns where the errors are smaller than the signal. Our research also highlights that an increase in the degree of large-scale convection aggregation has a nonlinear and negative feedback for mean warming.

Arctic climate feedback response to local sea-ice concentration and remote sea surface temperature changes in PAMIP simulations

Arctic climate feedback response to local sea-ice concentration and remote sea surface temperature changes in PAMIP simulations

Unveiling the Relationship Between Mediterranean Tropical‐Like Cyclones and Rising Sea Surface Temperature

AbstractLeveraging the Copernicus high‐resolution multi‐year Mediterranean Sea Surface Temperature (SST) dataset, 15 selected tropical‐like cyclones (TLCs) are analyzed with the objective of elucidating the anomalies of SST at the time of cyclogenesis and the connection between the change in SST during the cyclone lifetime and its characteristics. The long‐term SST increase associated with climate change is identified by comparing detrended and original anomalies. Detrending removes the effect of the intensification of SST anomaly over time, revealing that no significant anomalies generally emerge in the early stages of the TLC lifetimes. Conversely, winter events exhibit early‐stage positive SST anomalies. Also, high SST values were observed during the intensification of the most intense cyclones. A cold SST anomaly is left after the passage of the cyclones, due to the intense sea surface fluxes extracting heat from the sea.

Influence of Sea Surface Temperature Changes on the Development of Sprat (Sprattus sprattus phalericus) (Pisces: Clupeidae) Living on the South-Western Shelf of Crimea

A study of changes in sea surface temperature (SST) on the South-Western shelf of the Crimea in 2000–2020 was conducted. The equations of trends in the change of SST are found. It is shown that according to the nature of changes in the average annual sea temperature, three periods can be divided: 2000–2007, 2008–2013 and 2014–2020. The influence of changes in the average annual SST on the development of pelagic fish of the cold-waters complex (on the example of the Black Sea sprat) is considered. Changes in the main parameters of populations and their relationship with the change in the average annual SST were found. It was found that the observed increase in sea temperature negatively affected the development of the sprat population, the average age of the population decreased by 1.3 times, in general, the population was rejuvenated, the average size and weight of individuals decreased.

Composited sea surface responses to tropical cyclones in the Bay of Bengal during 2003–2020

Tropical cyclones (TCs) in the Bay of Bengal (BoB) caused significant changes in the sea surface as they passed through the sea. To quantitatively study the differences in oceanic responses caused by TCs during pre-monsoon and post-monsoon seasons in the BoB from 2003 to 2020 and the varying importance of TC intensity and translation speed in modulating oceanic responses, the oceanic environmental parameters affected by TCs were composited and analyzed. The spatial distributions show that the responses of sea surface temperature (SST) rather than chlorophyll-a (Chl-a) concentrations and sea surface salinity (SSS) coincided with the maximum response centers of the wind power index (WPi). All the temporal changes in SST, Chl-a, and SSS indicated that the changes induced by TCs began approximately 2–3 days before TC passage, continued to increase during cyclone passage, and then slowly returned to the initial state after at least 8 days. Compared with TC intensity, TC translation speed generally played a less important role in influencing the ocean responses of SST, Chl-a and SSS. This result is somewhat different from previous results in which the response of Chl-a was correlated with TC translation speed rather than TC intensity in the northern Indian Ocean. In addition, the SSS response was positively proportional (R = 0.886) to the TC translation speed in the BoB, which was different from that in the Northwest Pacific. The differences in the responses during pre-monsoon and post-monsoon seasons were mainly in terms of quantity, as all the composited results were similar. In addition, they were more pronounced in their responses but less significant in their correlations during pre-monsoon.