Optimal Sea Surface Temperature Research Articles

Deriving fine-scale patterns of sea surface temperature in coral reef habitats using the Landsat 8 thermal infrared sensor

The available sea surface temperature (SST) products are too coarse to assess the fine-scale (<1 km) SST variations related to coral bleaching. In this study, we proposed an optimal SST inversion model using Landsat 8 thermal infrared sensor (TIRS) images to derive fine-scale SST patterns in the coral reef habitats of the Xisha Islands, South China Sea. Our study included two parts: 1) six SST inversion models were developed using the radiative transfer method and the split window (SW) algorithm in the hot season and cool season, from which the optimal SST inversion model was determined; and 2) the optimal model was applied to 47 Landsat 8 TIRS images to derive the SST spatial and temporal pattern among the geomorphic zones of six reefs in hot and cool season conditions. Compared with the measured sea temperature data and the verified MODIS SST products, the SST6 model using the SW algorithm was optimal, with an RMSE of approximately 0.64°C in the hot season. The average SST results usually had a pattern of reef flat > lagoon > reef slope/offshore sea. The reef flat was usually approximately 0.05°C–0.2°C hotter than the lagoon in the hot season. The SST in the lagoon also increased from south to north and the shallow lagoon was usually warmer than the deep lagoon in the hot season. Our results suggested that scleractinian corals in the reef flat and the lagoon were more susceptible to bleaching-level thermal stress than other geomorphic zones. During the cool season, the SST fluctuated markedly among coral reefs and geomorphic zones.

The temporal and spatial distribution of sea fog in offshore of China based on FY-4A satellite data

Satellite remote sensing is an important instrument of sea fog monitoring. In order to study the temporal and spatial distribution characteristics of sea fog and the influence of sea surface temperature (SST) on the sea fog, based on sea fog monitoring and SST products from FY-4A satellite, the monthly variation of sea fog and monthly average SST in five typical sea areas (including Bohai Sea, Yellow Sea, East China Sea, Taiwan Strait and South China Sea) are statistically analyzed. The results show that the sea fog in offshore has strong regional and seasonal characteristics. From winter to autumn, the sea fog first appears in the Beibu Gulf of the South China Sea, the sea fog extends from South China Sea to East China Sea, and then to Yellow Sea, finally to Bohai Sea. Sea fog is related to sea surface temperature. By comparing the sea fog with the SST distribution, the optimal SST is from 7 °C to 25 °C when the sea fog happens.

Synchronous Variations in Abundance and Distribution of Ommastrephes bartramii and Dosidicus gigas in the Pacific Ocean

An analysis was performed in this study to investigate synchronous fluctuations in abundance and distribution of Ommastrephes bartramii in the Northwest Pacific Ocean and Dosidicus gigas in the Southeast Pacific Ocean. The impacts of two Nino indices and regional water surface temperature on the two squids during 2006–2015 were evaluated, which possibly can explain the observed synchronicity. Catch per unit effort (CPUE) and the latitudinal gravity centers (LATG) of fishing effort were used to indicate squid abundance and distribution, respectively. The results indicated that both the CPUE and LATG showed highly interannual variations and synchronous fluctuation with significant negative associations between the two squid species from September to November. Strong positive cross-correlations with 2-month lag was found between sea surface temperature (SST) anomaly in the Nino 3.4 and Nino 1+2 regions, which have significant linkage with the SST on the fishing ground of O. bartramii and D. gigas, respectively. Moreover, the proportion of favorable-SST area (PFSST) and the latitudinal location of the optimal SST for O. bartramii and D. gigas were positively correlated with the CPUE and LATG, respectively. Increased O. bartramii PFSST clearly corresponded to decreased D. gigas PFSST in phase as well as the latitudinal location of the optimal SST from September to November over 2006–2015. Our findings suggest that synchronous changes in abundance and distribution of the two squids were due to simultaneous variations in the PFSST and the latitudinal location of the optimal SST front which were affected by the SSTA changes in the Nino 3.4 and Nino 1+2 regions.

Global and regional evolution of sea surface temperature under climate change

Sea surface temperature (SST) has important local and remote influence on global climate through the distribution and transport of heat and moisture, which in turn affect precipitation and air temperature patterns across the globe. Thus, this work aims to assess the worldwide regionalization of the SST evolution for the 21 st century under the influence of climate change by means of: 1) division of the worldwide SST data in regions applying a K-means cluster procedure and validation of the most suitable CMIP5 models by a comparative analysis with SST data from Era-Interim reanalysis; 2) calculation of SST trends along the 21 st century and assessment of future SST differences between RCP 4.5 and RCP 8.5 greenhouse gas emission scenarios and historical SST data. Global climate model (GCM) projections show a SST warming worldwide although with different intensity depending on the region. Northern Hemisphere regions present a higher seasonal thermal amplitude comparing with equivalent regions in the Southern Hemisphere. Northern Hemisphere has also a higher annual SST increment than clusters in the Southern Hemisphere, independently of the future time period and climate scenario. The Northern Sub-Tropical cluster (STRN) shows the highest significant increment (4.34 °C on RCP 8.5). Under the RCP 4.5 climate scenario, SST trends from 1975 to 2100 range from 0.075 °C dec −1 at South Polar cluster (PRS) to 0.21 °C dec −1 at STRN cluster. Relatively to RCP 8.5 climatic scenario, SST trends change from 0.13 °C dec −1 at PRS cluster to 0.36 °C dec −1 at the North Polar cluster (PRN). • Identification of CMIP5 models with best SST performance. • The optimal worldwide SST division is eight clusters. • Northern Hemisphere clusters will present a higher SST increment.

SST Dynamics at Different Scales: Evaluating the Oceanographic Model Resolution Skill to Represent SST Processes in the Southern Ocean

AbstractIn this study we demonstrate the many strengths of scale analysis: we use it to evaluate the Nucleus for European Modelling of the Ocean model skill in representing sea surface temperature (SST) in the Southern Ocean by comparing three model resolutions: 1/12°, 1/4°, and 1°. We show that while 4–5 times resolution scale is sufficient for each model resolution to reproduce the magnitude of satellite Earth Observation (EO) SST spatial variability to within ±10%, the representation of ∼100‐km SST variability patterns is substantially (e.g., ∼50% at 750 km) improved by increasing model resolution from 1° to 1/12°. We also analyzed the dominant scales of the SST model input drivers (short‐wave radiation, air‐sea heat fluxes, wind stress components, wind stress curl, and bathymetry) variability with the purpose of determining the optimal SST model input driver resolution. The SST magnitude of variability is shown to scale with two power law regimes separated by a scaling break at ∼200‐km scale. The analysis of the spatial and temporal scales of dominant SST driver impact helps to interpret this scaling break as a separation between two different dynamical regimes: the (relatively) fast SST dynamics below ∼200 km governed by eddies, fronts, Ekman upwelling, and air‐sea heat exchange, while above ∼200 km the SST variability is dominated by long‐term (seasonal and supraseasonal) modes and the SST geography.

Influence of Spatial-Temporal and Environmental Factors on Larimichthys polyactis, Octopus variabilis, and Species Aggregated Set-Net CPUEs in Haizhou Bay, China

Set-nets are common alongshore fishing gear used in Haizhou Bay, which rely on flow to catch fish. The catch per unit effort (CPUE) of set-net is affected by spatial-temporal and environmental factors but no research has been conducted on this subject. In this study, we used generalized additive models (GAMs) to explore the influence of spatial-temporal and environmental factors on CPUEs of species aggregated, small yellow croaker (Larimichthys polyactis), and octopus (Octopus variabilis) based on logbooks investigations conducted at 4 stations in an alongshore area of Haizhou Bay from 2011 to 2012. The results showed that all CPUEs exhibited significant spatial-temporal differences at various scales. Aggregated CPUE was high when the sea surface temperature (SST) was 15–18°C and 20–23°C, which was mainly determined by life history traits of the octopus and small yellow croaker (optimal SSTs 14–17°C and 19–24°C, respectively). Chlorophyll-a concentration had significant influences on the aggregated, small yellow croaker and octopus CPUEs at optimal ranges of 3.8–6.2 mg m−3, 4.2–4.8 mg m−3 and 4.5–5.5 mg m−3, respectively. Flow through the net had positive relationships with CPUEs. The approximate logarithmic trends in regression curves had a critical point of 2.5 Mm3 d−1, which was the dividing point that differentiated whether the major factor affecting CPUEs was the flow velocity or the fishery resource. Our results from this study will help guide fishery production and improve catch rate of set-net fishing in Haizhou Bay.

Effect of extreme sea surface temperature events on the demography of an age-structured albatross population.

Climate changes include concurrent changes in environmental mean, variance and extremes, and it is challenging to understand their respective impact on wild populations, especially when contrasted age-dependent responses to climate occur. We assessed how changes in mean and standard deviation of sea surface temperature (SST), frequency and magnitude of warm SST extreme climatic events (ECE) influenced the stochastic population growth rate log(λs) and age structure of a black-browed albatross population. For changes in SST around historical levels observed since 1982, changes in standard deviation had a larger (threefold) and negative impact on log(λs) compared to changes in mean. By contrast, the mean had a positive impact on log(λs). The historical SST mean was lower than the optimal SST value for which log(λs) was maximized. Thus, a larger environmental mean increased the occurrence of SST close to this optimum that buffered the negative effect of ECE. This 'climate safety margin' (i.e. difference between optimal and historical climatic conditions) and the specific shape of the population growth rate response to climate for a species determine how ECE affect the population. For a wider range in SST, both the mean and standard deviation had negative impact on log(λs), with changes in the mean having a greater effect than the standard deviation. Furthermore, around SST historical levels increases in either mean or standard deviation of the SST distribution led to a younger population, with potentially important conservation implications for black-browed albatrosses.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events'.

Nitrogen fixation rates in the eastern Arabian Sea

The Arabian Sea experiences bloom of the diazotroph Trichodesmium during certain times of the year when optimal sea surface temperature and oligotrophic condition favour their growth. We measured nitrogen fixation rates in the euphotic zone during one such event in the Eastern Arabian Sea using 15N2 tracer gas dissolution method. The measured rates varied between 0.8 and 225 μmol N m−3 d−1 and were higher than those reported from most other oceanic regions. The highest rates (1739 μmol N m−2 d−1; 0–10 m) coincided with the growth phase of Trichodesmium and led to low δ15N (<2‰) of particulate organic matter. At stations not experiencing Trichodesmium bloom nitrogen fixation rates were low (0.9–1.5 μmol N m−3 d−1). Due to episodic events of diazotroph bloom, contribution of N2 fixation to the total nitrogen pool may vary in space and time.

Optimal Initial Excitations of Decadal Modification of the Atlantic Meridional Overturning Circulation under the Prescribed Heat and Freshwater Flux Boundary Conditions

AbstractWithin a three-dimensional ocean circulation model, the nonlinear optimal initial perturbations (NOIP) of sea surface salinity (SSS) and sea surface temperature (SST) to excite variability in the Atlantic meridional overturning circulation (AMOC) were obtained under prescribed heat and freshwater flux boundary conditions, using the conditional nonlinear optimal perturbation (CNOP) method. After 10 years, the optimal SSS and SST perturbations lead to reductions of the AMOC by 3.6 and 2.5 Sv (1 Sv = 106 m3 s−1), respectively, followed by multidecadal oscillations with a period of about 50 years. During the first 30 years, nonlinear processes have an important influence on the AMOC strength: convection strengthens the AMOC during years 0–2, zonal density advection promotes the slowdown of the AMOC during years 7–20, and meridional density advection inhibits the slowdown of meridional velocities in the upper ocean during years 5–18. The linear optimal initial perturbation (LOIP) was also computed using the first singular vector (FSV) method. For SSS perturbations with an amplitude of 0.5 psu, the LOIP will cause an underestimation of the amplitude of the multidecadal AMOC variability by about 1 Sv, compared to that induced by the NOIP. This underestimation will become more significant as the amplitudes of SSS perturbations increase.

On the comparison between seasonal predictive skill of global circulation models: Coupled versus uncoupled

AbstractThe study compares one‐ and two‐tiered forecasting systems as represented by the South African Weather Service Coupled Model and its atmosphere‐only version. In this comparative framework, the main difference between these global climate models (GCMs) resides in the manner in which the sea surface temperature (SST) is represented. The models are effectively kept similar in all other aspects. This strategy may allow the role of coupling on the predictive skill differences to be better distinguished. The result reveals that the GCMs differ widely in their performances and the issue of superiority of one model over the other is mostly dependent on the ability to a priori determine an optimal global SST field for forcing the atmospheric general circulation model (AGCM). Notwithstanding, the AGCM's fidelity is reasonably reduced when the AGCM is constrained with persisting SST anomalies to the extent to which the coupled general circulation model's superiority becomes noticeable. The result suggests that the boundary forcing coming from the optimal SST field plays a significant role in leveraging a reasonable equivalency in the predictive skill of the two GCM configurations.

Occurrence and density of Pacific saury Cololabis saira larvae and juveniles in relation to environmental factors during the winter spawning season in the Kuroshio Current system

AbstractThe occurrence and density of Pacific saury Cololabis saira larvae and juveniles were examined in relation to environmental factors during the winter spawning season in the Kuroshio Current system, based on samples from extensive surveys off the Pacific coast of Japan in 2003–2012. Dense distributions of larvae and juveniles were observed in areas around and on the offshore side of the Kuroshio axis except during a large Kuroshio meander year (2005). The relationships of larval and juvenile occurrence and density given the occurrence to sea surface temperature (SST), salinity (SSS), and chlorophyll‐a concentration (CHL) were examined by generalized additive models for 10‐mm size classes up to 40 mm. In general, the optimal SST for larval and juvenile occurrence and density given the occurrence was consistently observed at 19–20°C. The patterns were more complex for SSS, but a peak in occurrence was observed at 34.75–34.80. In contrast, there were negative relationships of occurrence and density given the occurrence to CHL. These patterns tended to be consistent among different size classes, although the patterns differed for the smallest size class depending on environmental factors. Synthetically, the window for spawning and larval and juvenile occurrence and density seems to be largely determined by physical factors, in particular temperature. The environmental conditions which larvae and juveniles encounter would be maintained while they are transported. The survival success under the physically favorable but food‐poor conditions of the Kuroshio Current system could be key to their recruitment success.

Diversity of deep-water cetaceans and primary productivity

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 408:1-5 (2010) - DOI: https://doi.org/10.3354/meps08619 FEATURE ARTICLE Diversity of deep-water cetaceans and primary productivity Hal Whitehead*, Kristin O’Brien, Boris Worm Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada *Email: hwhitehe@dal.ca ABSTRACT: Recently, it has been suggested that mammal diversity both on land and in the sea is controlled by patterns of primary productivity. Here we tested the hypotheses that large-scale patterns of marine mammal diversity are linked to primary productivity, sea surface temperature (SST) or a combination of these 2 factors. We used a consistently sampled sightings database of deep-water cetaceans in the Atlantic and Pacific Oceans, along with in situ SST measurements and 3 satellite-derived productivity measures matched spatially and temporally to available sightings. Cetacean genus richness peaked in regions of high primary productivity (>1000 to 1500 mg C m–2 d–1), but most of this effect is captured by optimal SST in those same regions. Our results show that the best-supported, explanatory models of cetacean diversity included SST, while the addition of satellite-derived measures of productivity did not improve predictive capacity. Marine mammal richness globally peaks around 40°N and S, and may result more directly from optimal SST at these latitudes rather than high oceanic productivity. KEY WORDS: Biodiversity · Productivity · Sea surface temperature · Cetacean Full text in pdf format Information about this Feature Article NextCite this article as: Whitehead H, O’Brien K, Worm B (2010) Diversity of deep-water cetaceans and primary productivity. Mar Ecol Prog Ser 408:1-5. https://doi.org/10.3354/meps08619 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 408. Online publication date: June 03, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

On the Assessment of Nonlocal Climate Feedback. Part II: EFA-SVD and Optimal Feedback Modes*

Abstract The equilibrium feedback assessment (EFA) is combined with the singular value decomposition (SVD) to assess the large-scale feedback modes from a lower boundary variability field onto an atmospheric field. The leading EFA-SVD modes are the optimal feedback modes, with the lower boundary forcing patterns corresponding to those that generate the largest atmospheric responses, and therefore provide upper bounds of the feedback response. The application of EFA-SVD to an idealized coupled ocean–atmosphere model demonstrates that EFA-SVD is able to extract the leading feedback modes successfully. Furthermore, these large-scale modes are the least sensitive to sampling errors among all the feedback processes and therefore are the most robust for statistical estimation. The EFA-SVD is then applied to the observed North Atlantic ocean–atmosphere system for the assessment of the sea surface temperature (SST) feedback on the surface heat flux and the geopotential height, respectively. The dominant local negative feedback of SST on heat flux is confirmed, with an upper bound of about 40 W m−2 K−1 for basin-scale anomalies. The SST also seems to exert a strong feedback on the atmospheric geopotential height: the optimal SST forcing has a dipole pattern that generates an optimal response of a North Atlantic Oscillation (NAO) pattern, with an upper bound of about 70 m K−1 at 500 hPa. Further issues on the EFA-SVD analysis are also discussed.

Spatial and temporal migration modeling for stock of Pacific saury Cololabis saira (Brevoort), incorporating effect of sea surface temperature

A model is proposed that expresses the spatial and temporal migration pattern for stock of Pacific saury Cololabis saira (Brevoort), in order to investigate the effect of sea surface temperature (SST) on migration rates. Two factors are considered: (i) Saury emigrate to waters of an optimal SST zone; and (ii) saury immigrate from water zone that is extremely cold for saury. Parameters of migration and initial levels of stock are estimated with a maximum likelihood method based on catch per unit effort (CPUE) data for 1995–2001. The best model was selected using Akaike’s information criteria. The results suggested that the emigration rate to southern adjacent regions is dependent on the coverage proportion of their waters under some threshold temperatures; 20°C to Doutou and Sanriku, 23°C to Joban and Izu.

Attribution of Atmospheric Variations in the 1997–2003 Period to SST Anomalies in the Pacific and Indian Ocean Basins

Abstract The individual impacts of sea surface temperature (SST) anomalies in the deep tropical eastern–central Pacific (DTEP) and Indo-western–central Pacific (IWP) on the evolution of the observed global atmospheric circulation during the 1997–2003 period have been investigated using a new general circulation model. Ensemble integrations were conducted with monthly varying SST conditions being prescribed separately in the DTEP sector, the IWP sector, and throughout the World Ocean. During the 1998–2002 subperiod, when prolonged La Niña conditions occurred in DTEP and the SST in IWP was above normal, the simulated midlatitude atmospheric responses to SST forcing in the DTEP and IWP sectors reinforced each other. The anomalous geopotential height ridges at 200 mb in the extratropics of both hemispheres exhibited a distinct zonal symmetry. This circulation change was accompanied by extensive dry and warm anomalies in many regions, including North America. During the 1997–98 and 2002–03 El Niño events, the SST conditions in both DTEP and IWP were above normal, and considerable cancellations were simulated between the midlatitude responses to the oceanic forcing from these two sectors. The above findings are contrasted with those for the 1953–58 and 1972–77 periods, which were characterized by analogous SST developments in DTEP, but by cold conditions in IWP. It is concluded that a warm anomaly in IWP and a cold anomaly in DTEP constitute the optimal SST configuration for generating zonally elongated ridges in the midlatitudes. Local diagnoses indicate that the imposed SST anomaly alters the strength of the zonal flow in certain longitudinal sectors, which influences the behavior of synoptic-scale transient eddies farther downstream. The modified eddy momentum transports in the regions of eddy activity in turn feed back on the local mean flow, thus contributing to its zonal elongation. These results are consistent with the inferences drawn from zonal mean analyses, which accentuate the role of the eddy-induced circulation on the meridional plane.

Global Sea Surface Temperature Analyses: Multiple Problemsand Their Implications for Climate Analysis, Modeling, and Reanalysis

A comprehensive comparison is made among four sea surface temperature (SST) datasets: the optimum interpolation (OI) and the empirical orthogonal function reconstructed SST analyses from the National Centers for Environmental Prediction (NCEP), the Global Sea-Ice and SST dataset (GISST, version 2.3b) from the United Kingdom Meteorological Office, and the optimal smoothing SST analysis from the Lamont-Doherty Earth Observatory (LDEO). Significant differences exist between the GISST and NCEP 1961–90 SST climatologies, especially in the marginal sea-ice zones and in regions of important small-scale features, such as the Gulf Stream, which are better resolved by the NCEP product. Significant differences also exist in the SST anomalies that relate strongly to the number of in situ observations available. In recent years, correlations between monthly anomalies are less than 0.75 south of about 10°N and are lower still over the southern oceans and parts of the tropical Pacific where root-mean-square differences ...