Mean Sea Surface Temperature Research Articles

The Effect of Increasing Temperature and Feeding Time on Feeding Rate on Soft Coral Sarcophyton sp. and Sinularia sp.

Soft corals (Alcyoniidae) can obtain the nutrients through the algae symbiont (zooxanthellae) and/or captures the prey with their tentacles. Increased mean sea surface temperatures cause damage to coral reef ecosystems, one of those mechanisms is reducing the feeding capacity in soft corals. Thus, this study aims to examine the feeding rates of soft corals Sinularia sp. and Sarcophyton sp. at different temperatures, to determine the effect of increasing temperature, feeding time and interaction between those factors on feeding rates of soft corals Sarcophyton sp. and Sinularia sp. samples of Soft corals were obtained from the cultured of PT. Dinar Darum Lestari in Sumberkima Bay Waters, Buleleng Regency. before the experiment, coral fragments were acclimatized for 2 weeks and fed twice a week at 26 ° C (control temperature). The Experiment started by increasing the water temperature in the aquarium 1°C every hour to reach 31°C (stress temperature). Once the temperature reached, it held for 5 days. Each aquarium (26 and 31°C) was fed by Artemia salina on the second and fourth days with density 100 animals/fragments in the morning for 3 hours. The remained prey was taken by Pasteur pipette and counted manually. The results showed that there was no significant difference of feeding rates in Sarcophyton sp. dan Sinularia sp. at both control and stress temperatures because both types of soft coral fragments have relatively the same temperature tolerance. The increased temperature significantly affected the feeding rate in both soft corals (P <0,000). However, feeding time and interaction between temperature and feeding time did not have a significant effect on the feeding rate. It is assumed that the increased temperature reduces the feeding rate in these soft corals. Moreover, these soft coral seems stress due to continuously incubate in high temperature (31°C) caused no significant difference in the feeding rates at all feeding times. keywords: soft coral, Sarcophyton sp., Sinularia sp., increased temperature., feeding rate, feeding time

Development, Amplification, and Decay of Atlantic/European Summer Weather Patterns Linked to Spring North Atlantic Sea Surface Temperatures

AbstractA recent study identified a relationship between North Atlantic Ocean sea surface temperature (SST) gradients in spring and a specific pattern of atmospheric circulation in the following summer: the summer east Atlantic (SEA) pattern. It was shown that the SEA pattern is closely associated with meridional shifts in the eddy-driven jet in response to anomalous SST gradients. In this study, the physical mechanisms underlying this relationship are investigated further. It is shown that the predictable SEA pattern anomalies appear in June–July and undergo substantial amplification between July and August before decaying in September. The associated SST anomalies also grow in magnitude and spatial extent from June to August. The question of why the predictable atmospheric anomalies should occur in summer is addressed, and three factors are identified. The first is the climatological position of the storm track, which migrates poleward from spring to summer. The second is that the magnitude of interannual SST variability underlying the storm track peaks in summer, both in absolute terms, and relative to the underlying mean SST gradient. The third factor is the most interesting. We identify a positive coupled ocean–atmosphere feedback, which operates in summer and leads to the amplification of both SST and atmospheric circulation anomalies. The extent to which the identified processes are captured in the HadGEM3-GC2 climate model is also assessed. The model is able to capture the relationship between spring North Atlantic SSTs and subsequent ocean–atmosphere conditions in early summer, but the relationship is too weak. The results suggest that the real world might be more predictable than is inferred from the models.

Foraging ecology of a marine top predator in the Eastern Tropical Pacific over 3\xa0years with different ENSO phases

The El Niño Southern Oscillation (ENSO) is a recurrent climatic pattern with important ecological consequences for seabirds due to its impacts on the abundance and distribution of food resources. We investigated the effects of ENSO phases on the foraging ecology of a marine top predator at Clarion Island in the Eastern Tropical Pacific using GPS and time-depth recorder data and regurgitates from incubating masked boobies (Sula dactylatra) during 3 consecutive years. Foraging locations were recorded in 2016 (El Niño, one female, three males), 2017 (neutral; six females, nine males), and 2018 (La Niña; eight females, ten males). Local sea surface temperature (SST) and chlorophyll-a concentration (CHL) within the birds’ foraging range were compared among the 3 years. Regurgitates were collected opportunistically from 25 and 31 incubating adults in 2017 and 2018, respectively. Average local CHL and SST were similar among years (mean SST 25 °C; mean CHL 0.10 and of 0.09 mg m−3 in January and March, respectively). Masked boobies travelled a maximum of 66 ± 34 km from the colony. The maximum trip duration was 7.7 ± 3.4 h and total distance travelled during a foraging trip was 164 ± 73 km, with no sex- or year-related differences. Masked boobies mainly caught flying fish, but their diet also included one squid and six other fish families. In contrast to previously reported changes in foraging ecology of seabirds, masked boobies at Clarion Island seemed to be unaffected during El Niño, because the local oceanography was relatively unperturbed by ENSO oscillations.

Weekly sea surface temperature from SNPP-VIIRS data using open source software

The objective of this study is to make weekly mean sea surface temperature (SST) from SNPP-VIIRS satellite data. The data used were SST data every afternoon pass, from 13 to 19 May 2019. The data were obtained from Remote Sensing Technology and Data Center, LAPAN. From 12 samples data used showed that pixel size of each data are different, with range between 0.006737548 - 0.006858158 degree. The pixel size should be exactly the same to do data overlay. Then, the pixel size was resized become 0.00675 degree. This process was carried out using Reprojection Menu in QGIS software. The next process was calculating weekly mean SST every pixel. The mean SST was calculated only on pixels that have SST values. The calculation was not carried out on cloud, cloud shadow, land, and out of coverage data. The tolerance of coordinate position between pixels are less than 0.5 of pixel size. Weekly mean SST calculation process was executed using mean function in R software. The result of mean SST showed some possible error SST values. The errors were found in these conditions: 1) in coastal areas where possible mixed pixels of land and water 2) near cloud, where possible mixed pixel of cloud, cloud shadow, and water, 3) pixels with (extremely) high SST values near clouds. To overcome these conditions, some median type filters were applied. Therefore, weekly mean SST from SNPP-VIIRS data that smooth and minimum cloud cover can be obtained.

Multispecific coral spawning events and extended breeding periods on an equatorial reef

Scleractinian corals often reproduce in synchronized spawning events to maximize gamete fertilization and coral larval production. The extent of spawning synchrony and its timing vary among coral taxa and among biogeographic regions. Information is, however, limited, especially for equatorial reefs, hindering the identification of environmental cues that influence gametogenic cycles and spawning. To investigate the timing of gamete maturation and spawning in Palau and their association with environmental cues, we monitored tagged colonies from 11 common coral species within three families over 21 months. We then combined our findings with previous available information to more broadly summarize the known coral spawning patterns in Palau. In combination with previous observations, our data confirmed the occurrence of an extended coral spawning season in Palau, spreading over 9 months. Some coral taxa participated in synchronous multispecific spawning events, with the largest occurring throughout April and May. Other coral taxa, including Montipora corals, displayed inter- and intra-specific spawning asynchrony. Consequently, environmental cues associated with spawning patterns differed among species. The largest Acropora spawning event of the year (March–April) was associated with the lowest yearly high tides and a monthly mean sea surface temperature around 29 °C. Massive Porites spawned predominantly in April and May, associated with increased monthly levels of solar insolation. Porites rus spawned in June–August and was associated with longest monthly day length. Our study demonstrates that Palauan coral assemblages have complex patterns of multispecific spawning events throughout most of the year, which may have important implications for larval dispersal, supply and recruitment patterns, influencing the resilience of coral reefs in this region.

The changes in ENSO-induced tropical Pacific precipitation variability in the past warm and cold climates from the EC-Earth simulations

The El Niño-Southern Oscillation (ENSO) is one of the most significant climate variability signals. Studying the changes in ENSO-induced precipitation variability (ENSO precipitation) in the past climate offers a possibility to a better understanding of how they may change under future climate conditions. This study uses simulations performed with the European community Earth-System Model (EC-Earth) to investigate the relative contributions of dynamic effect (the circulation anomalies together with the climatological specific humidity) and thermodynamic effect (the specific humidity anomalies together with the climatological circulation) on the changes in ENSO precipitation in the past warm and cold climates, represented by the Pliocene and the Last Glacial Maximum (LGM), respectively. The results show that the changes in ENSO precipitation are intensified (weakened) over the tropical western Pacific but weakened (intensified) over the tropical central Pacific in Pliocene (LGM) compared with the pre-industrial (PI) simulation. Based on the decomposed moisture budget equation, these changes in ENSO precipitation patterns are highly related to the dynamic effect. The mechanism can be understood as follows: the zonal gradient of the mean sea surface temperature (SST) over the tropical Indo-Pacific is increased (reduced) during the Pliocene (LGM), leading to the strengthening (weakening) of Pacific Walker Circulation as well as a westward (eastward) shift. In the Pliocene, the westward shift of Walker Circulation results in an increased (decreased) ENSO-induced low-level vertical velocity variability in the tropical western Pacific (central Pacific), and, in turn, favoring convergent (divergent) moisture transport through a dynamic process, and then causing intensified (weakened) ENSO precipitation there. The opposite mechanism exists in LGM. These results suggest that changes in the zonal SST gradient over tropical Indo-Pacific under different climate conditions determine the changes in ENSO precipitation through a dynamic process.

Assessing the role of the ocean–atmosphere coupling frequency in the western Maritime Continent rainfall

High-frequency interactions between the ocean and atmosphere have the potential to affect lower frequency or mean state climate in various regions. Here we examine the importance of sub-daily air-sea interactions over the Maritime Continent region to the rectification of longer timescale variation. In order to determine the importance of these high-frequency interactions, we conducted two regional ocean–atmosphere coupled simulations over the Maritime Continent where exchanges between the oceanic and atmospheric components are performed either every hour (i.e. resolving diurnal changes) or every day. We find that coupling frequency has a significant influence on mean sea surface temperature (SST) and the mean state and diurnal cycle of rainfall over certain regions of the western Maritime Continent where air-sea interactions are strong during the Asian monsoon season, with little effect in other regions or seasons. Without sub-daily air-sea interactions, the mean SST along the southwest off Sumatra is ~ 2 °C warmer during the period from June to October as a result of a deepening of thermocline along the coast. This deepening is linked to anomalous downwelling equatorial eastward propagating Kelvin waves triggered by westerly anomalies in the eastern equatorial Indian Ocean. In addition, the mean rainfall in the vicinity of ocean warming increases, thereby producing an enhanced barrier layer that also provides a positive warming feedback. Although the coupling frequency has little impact on the timing of the rainfall diurnal cycle, suppression of sub-daily coupling significantly changes the diurnal rainfall amplitude causing a relative decrease (increase) in amplitude over the coast of Northwestern (Southwestern) Sumatra during the South Asian monsoon season.

Port Jackson Shark Growth Is Sensitive to Temperature Change

Climatic effects on the growth of apex marine predators – such as sharks – are poorly understood; moreover, shifts in shark growth are primarily attributed to fishing pressure. This paucity of information impedes management and conservation planning for these taxa. Using vertebral increment patterning as a proxy of somatic growth, this study reconstructed mean growth of the philopatric and demersal Heterodontus portusjacksoni population from Gulf St Vincent (South Australia). A biochronology of shark growth spanning 1996 to 2010 was developed using linear mixed effect models. The biochronology showed considerable year-to-year deviations in growth that were significantly and negatively correlated with mean sea surface temperatures during the species’ breeding season (July to November). These findings are consistent with mesocosm experiments and support the influence of changing climates on shark growth; particularly in an inshore, demersal and highly philopatric shark species. It is likely that the effects of environmental variation occur in a species-specific manner, governed by life history strategies and ecological requirements. In this manner, life history traits might aid in estimating species vulnerability to climate change.

Environmental drivers and indicators of change in habitat and fish assemblages within a climate change hotspot

Climate-driven environmental change is predicted to accelerate over the coming decades. Anticipating the ecological consequences requires a fundamental understanding of how environmental variables influence key habitats and species. Southeastern Australia is a marine climate change hotspot, characterised by rapidly increasing sea surface temperatures, strengthening currents and increasing storm frequency. To understand ecosystem responses to environmental drivers in this region, and to anticipate future climate-driven change, we examined the spatial distribution and environmental relationships of key marine habitats, fish assemblages, and the ecologically important urchin Centrostephanus rodgersii along ∼1000 km of reef off southeastern Australia using towed video transects. We also identified potential biological indicators of climate-driven changes to rocky reef ecosystems, based on ecological importance, ease of measurement, and sensitivity to one or more climate-affected environmental drivers. Significant latitudinal gradients were identified for biota, with habitats, fish assemblages and urchin densities all varying latitudinally with sea surface temperature and current strength. Wave energy and distance offshore were identified as drivers of biota at local-scales (100–1000 m). These results indicate that climate-driven changes to various environmental factors will alter the composition and distribution of marine biota, at a variety of scales. The average thermal niche for fish assemblages varied significantly with changing mean sea surface temperature and may be a sentinel indicator of climate-driven changes. Coverage of the kelp Ecklonia radiata, densities of the urchin C. rodgersii, and coral cover were also confirmed as potential valuable biological indicators of climate-driven changes. These indicators, and the widespread baseline data assembled in this study, will facilitate detection of future changes to rocky reef ecosystems in southeastern Australia.

Seasonal and Interannual Variability of the Indo-Pacific Warm Pool and its Associated Climate Factors Based on Remote Sensing

With satellite observed Sea Surface Temperature (SST) accumulated for multiple decades, multi-time scale variabilities of the Indo-Pacific Warm Pool are examined and contrasted in this study by separating it into the Indian Ocean sector and the Pacific Ocean sector. Surface size, zonal center, meridional center, maximum SST and mean SST as the practical warm pool properties are chosen to investigate the warm pool variations for the period 1982–2018. On the seasonal time scale, the oscillation of the Indian Warm Pool is found much more vigorous than the Pacific Warm Pool on size and intensity, yet the interannual variabilities of the Indian Warm Pool and the Pacific Warm Pool are comparable. The Indian Warm Pool has weak interannual variations (3–5 years) and the Pacific Warm Pool has mighty interdecadal variations. The size, zonal movement and mean SST of the Indian Ocean Warm Pool (IW) are more accurate to depict the seasonal variability, and for the Pacific Ocean Warm Pool (PW), the size, zonal and meridional movements and maximum SST are more suitable. On the interannual scale, except for the meridional movements, all the other properties of the same basin have similar interannual variation signals. Following the correlation analysis, it turns out that the Indian Ocean basin-wide index (IOBW) is the most important contributor to the variabilities of both sectors. Lead-lag correlation results show that variation of the Pacific Ocean Warm Pool leads the IOBW and variation of the Indian Ocean Warm Pool is synchronous with the IOBW. This indicates that both sectors of the Indo-Pacific Warm Pool are significantly correlated with basin-wide warming or cooling.

Decadal to interdecadal variability in TEX86 temperature on the inner shelf of the East China Sea over the last 3.7 kyr

To understand the long-term environmental evolution of the East China Sea (ECS) and adjacent areas, the variation in TEX86H-derived sea surface temperature (SST) at site T08 collected from the mud area on the inner continental shelf of the ECS over the last 3725 years was reconstructed. The core-top TEX86H SST is 23.2 °C, close to the annual mean SST (22.9 °C) at site T08. The branched and isoprenoid tetraether (BIT) index, which is a proxy for soil organic matter, ranges from 0.029 to 0.059, indicating that the influence of terrestrial input on the TEX86H SST proxy is negligible. The ratio between glycerol dialkyl glycerol tetraethers (GDGTs) GDGT-0 and GDGT-5 (R0/5), which is used to indicate the contribution of methanogenic archaea to the GDGT pool, varies between 0.04 and 0.62, suggesting a minor influence of methanogens on the TEX86H proxy. During the past 3725 years, variation in TEX86H SST can be divided into three periods with an overall increasing trend. During Period I (3725–2500 yr BP), TEX86H SST ranged from 19.0 to 20.6 °C with a mean of 20.1 °C. The values were generally relatively low but with marked fluctuation, attributed to increased input of cold coastal water caused by a strengthened East Asian winter monsoon (EAWM) and a weakened Kuroshio Current (KC). During Period II (2500–750 yr BP), after a low-temperature period at 2400–2200 yr BP, TEX86H SST increased gradually from 19.2 to 23.5 °C. During this period, an intensified East Asian summer monsoon (EASM) and a strengthened KC and Taiwan Warm Current (TWWC) transported warm water from low-latitude areas to ECS coastal areas. During Period III (750 yr BP to present), TEX86H SST increased gradually and reached a maximum (24.2 °C) at ∼565 yr BP. Subsequently, TEX86H SST decreased and reached a low value (21.9 °C) at ∼279 yr BP. During the period (<750 yr BP), higher TEX86H SST values were caused mainly by intensified KC, whereas lower values corresponded to the Little Ice Age. Spectral analysis reveals that variation in TEX86H SST exhibits periodicities of 175, 80, and 68 years, consistent with the periodicities of solar activity.

Global temperature calibration of the Long chain Diol Index in marine surface sediments

The Long chain Diol Index (LDI) is a relatively new organic geochemical proxy for sea surface temperature (SST), based on the abundance of the C30 1,15-diol relative to the summed abundance of the C28 1,13-, C30 1,13- and C30 1,15-diols. Here we substantially extend and re-evaluate the initial core top calibration by combining the original dataset with 172 data points derived from previously published studies and 262 newly generated data points. In total, we considered 595 globally distributed surface sediments with an enhanced geographical coverage compared to the original calibration. The relationship with SST is similar to that of the original calibration but with considerably increased scatter. The effects of freshwater input (e.g., river runoff) and long-chain diol contribution from Proboscia diatoms on the LDI were evaluated. Exclusion of core-tops deposited at a salinity < 32 ppt, as well as core-tops with high Proboscia-derived C28 1,12-diol abundance, resulted in a substantial improvement of the relationship between LDI and annual mean SST. This implies that the LDI cannot be directly applied in regions with a strong freshwater influence or high C28 1,12-diol abundance, limiting the applicability of the LDI. The final LDI calibration (LDI = 0.0325 × SST + 0.1082; R2 = 0.88; n = 514) is not statistically different from the original calibration of Rampen et al. (2012) (https://doi.org/10.1016/j.gca.2012.01.024), although with a larger calibration error of 3 °C. This larger calibration error results from several regions where the LDI does not seem to have a strong temperature dependence with annual mean SST, posing a limitation on the application of the LDI.

Real World and Tropical Cyclone World. Part II: Sensitivity of Tropical Cyclone Formation to Uniform and Meridionally Varying Sea Surface Temperatures under Aquaplanet Conditions

AbstractThis study aims to investigate the response of simulated tropical cyclone formation to specific climate conditions, using an idealized aquaplanet framework of an ~40-km-horizontal-resolution atmospheric general circulation model. Two sets of idealized model experiments have been performed, one with a set of uniformly distributed constant global sea surface temperatures (SSTs) and another in which varying meridional SST gradients are imposed. The results show that the strongest relationship between climate and tropical cyclone formation is with vertical static stability: increased static stability is strongly associated with decreased tropical cyclone formation. Vertical wind shear and midtropospheric vertical velocity also appear to be related to tropical cyclone formation, although below a threshold value of wind shear there appears to be little relationship. The relationship of tropical cyclone formation with maximum potential intensity and mean sea surface temperature is weak and not monotonic. These simulations strongly suggest that vertical static stability should be part of any climate theory of tropical cyclone formation.

Comparison Between Early and Late 21stC Phytoplankton Biomass and Dimethylsulfide Flux in the Subantarctic Southern Ocean

Time-series of chlorophyll-a (CHL), a proxy for phytoplankton biomass, and various satellite-derived climate indicators are compared in a region of the Subantarctic Southern Ocean (40°−60°S, 110°−140°E) for years 2012−2014. CHL reached a minimum in winter (June) and a maximum in late summer (early February). Zonal mean CHL decreased towards the south. Mean sea surface temperature (SST) ranged between 8℃ and 15℃ and peaked in late February. CHL and SST were positively correlated from March to June, negatively correlated from July to September. CHL and wind speed (WIND) were negatively correlated with peak WIND occurred in winter. Wind direction (WIRD) was mostly in the southwest to westerly direction. The Antarctic Oscillation index (AAO) and CHL were negatively correlated (R = −0.58), indicating that as synoptic wind systems move southwards, CHL increases, and conversely when wind systems move northwards, CHL decreases. A genetic algorithm is used to calibrate the biogeochemical DMS model’s key parameters. Under 4 × CO2 (after year 2100) Regional mean SST increases 12%−17%, WIND increases 1.2 m s−1, Cloud Cover increases 4.8% and mixed layer depth (MLD) decreases 48m. The annual CHL increases 6.3%. The annual mean DMS flux increase 25.2%, increases 37% from day 1 to day 280 and decrease 3% from day 288 to day 360. The general increase of DMS flux under 4 × CO2 conditions indicates the Subantarctic regional climate would be affected by changes in the DMS flux, with the potential for a cooling effect in the austral summer and autumn.

A new sea surface temperature proxy based on bacterial 3-hydroxy fatty acids

3-Hydroxy fatty acids (3-OH-FAs), derived from Gram-negative bacterial outer membranes, have received recent attention for their potential as new terrestrial pH and temperature proxies for palaeoclimate studies. However, it is not known whether 3-OH-FA based proxies can be developed and applied to the marine environment. Here we analyze 3-OH-FAs from a latitudinal transect of marine surface sediments from the North Pacific Ocean (12°N to 61°N with a annual mean sea surface temperature (SST) range of 28.1–1.3 °C). The results show that distributions of 3-OH-FAs in marine sediments yield overall higher abundances of anteiso 3-OH-FA homologues compared to soils. Furthermore, 16S rRNA gene sequencing of the marine sediments and soils shows the Gram-negative bacterial community is dominated by Proteobacteria (ca. 94%) at the phylum level. In contrast, in regional soils the Gram-negative bacterial community is more diverse with significant contributions from Proteobacteria (ca. 50%), Acidobacteria (ca. 24%), Verrucomicrobia (6%), Bacteroidetes (6%) and other phyla. These distinct genomic and molecular differences suggest distinctly different aggregate compositions of bacteria that produce 3-OH-FAs in the marine realm vs soils. Moreover, we find that the ratio of anteiso to normal C13 3-OH-FA (RAN13) measured in surface sediments is highly correlated with annual mean SST throughout the temperature transect. When applied to a short sediment core from the East China Sea, the SST changes reconstructed by the RAN13 proxy are comparable to instrumental SST data. These findings demonstrate that RAN13 and potentially other, so far undiscovered, proxies based on 3-OH-FAs have potential for environmental and palaeoclimate applications in marine environments.

Modelling habitat use by the Guiana dolphin, Sotalia guianensis, in south‐eastern Brazil: Effects of environmental and anthropogenic variables, and the adequacy of current management measures

Abstract Species distribution modelling has been used to identify critical habitats for the delimitation of Marine Protected Areas. Although Marine Protected Areas may often overlap with the distribution of key marine species, illegal human activities often continue within these areas, causing negative impacts on the local biodiversity. A generalized linear model with spatial eigenvector mapping was used to investigate, for the first time, the influence of environmental variables and anthropic activities on the number of Guiana dolphin, Sotalia guianensis sightings/grid, and to determine whether a Marine Reserve, in south‐eastern Brazil, is adequate for the protection of the local population. Data were collected between May 2007 and October 2013 onboard a 7.5‐m vessel with an inboard engine. The models for the different periods (annual, dry, and rainy seasons) all indicated that depth, the distance to seafood farms and fishing grounds, and mean sea surface temperatures influenced the distribution of the dolphins within the study area. The annual and seasonal models predicted that the dolphins prefer a continuous area between Cedro and Pico Islands, a large area that lies outside the limits of the Marine Reserve. Although the habitat of Ilha Grande bay is still much less degraded than that inhabited by other nearby Guiana dolphin populations, the results of the present study indicate that anthropic activities in this area influence habitat use by the dolphins. Less than 30% of the area used by the dolphins is protected by the Tamoios Ecological Station (ESEC Tamoios). Sotalia guianensis is classified as ‘Vulnerable’ in Brazil, although the marine reserve (ESEC Tamoios) does not protect the core area used by the local dolphin population. The results of the present study provide specific locations for the creation of a new multiple‐use MPA, as suggested by the Brazilian National Action Plan for the Conservation of Small Cetaceans, or the inclusion of a special management programme for the area between Cedro and Pico islands to better protect the dolphins in the ESEC Tamoios buffer zone. The continuation of surveys to better understand the current and future impacts of human activities, and the development of a closer interaction with both the local community and local stakeholders will help to safeguard Ilha Grande Bay and the local Guiana dolphin population.

On the Correspondence between Seasonal Forecast Biases and Long-Term Climate Biases in Sea Surface Temperature

AbstractThe correspondence between mean sea surface temperature (SST) biases in retrospective seasonal forecasts (hindcasts) and long-term climate simulations from five global climate models is examined to diagnose the degree to which systematic SST biases develop on seasonal time scales. The hindcasts are from the North American Multimodel Ensemble, and the climate simulations are from the Coupled Model Intercomparison Project. The analysis suggests that most robust climatological SST biases begin to form within 6 months of a realistically initialized integration, although the growth rate varies with location, time, and model. In regions with large biases, interannual variability and ensemble spread is much smaller than the climatological bias. Additional ensemble hindcasts of the Community Earth System Model with a different initialization method suggest that initial conditions do matter for the initial bias growth, but the overall global bias patterns are similar after 6 months. A hindcast approach is more suitable to study biases over the tropics and subtropics than over the extratropics because of smaller initial biases and faster bias growth. The rapid emergence of SST biases makes it likely that fast processes with time scales shorter than the seasonal time scales in the atmosphere and upper ocean are responsible for a substantial part of the climatological SST biases. Studying the growth of biases may provide important clues to the causes and ultimately the amelioration of these biases. Further, initialized seasonal hindcasts can profitably be used in the development of high-resolution coupled ocean–atmosphere models.

Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations

AbstractIn this study we demonstrate the potential of a kinetic energy backscatter scheme for use in global ocean simulations. Ocean models commonly employ (bi)harmonic eddy viscosities causing excessive dissipation of kinetic energy in eddy‐permitting simulations. Overdissipation not only affects the smallest resolved scales but also the generation of eddies through baroclinic instabilities, impacting the entire wave number spectrum. The backscatter scheme returns part of this overdissipated energy back into the resolved flow. We employ backscatter in the FESOM2 multiresolution ocean model with a quasi‐uniform 1/4° mesh. In multidecadal ocean simulations, backscatter increases eddy activity by a factor 2 or more, moving the simulation closer to observational estimates of sea surface height variability. Moreover, mean sea surface height, temperature, and salinity biases are reduced. This amounts to a globally averaged bias reduction of around 10% for each field, which is even larger in the Antarctic Circumpolar Current. However, in some regions such as the coastal Kuroshio, backscatter leads to a slight overenergizing of the flow and, in the Antarctic, to an unrealistic reduction of sea ice. Some of the bias increases can be reduced by a retuning of the model, and we suggest related adjustments to the backscatter scheme. The backscatter simulation is about 2.5 times as expensive as a simulation without backscatter. Most of the increased cost is due to a halving of the time step to accommodate higher simulated velocities.

Chlorophyll-a variability during positive IOD - the east season period in 2019 in Padang Sea, Indonesia

This study aimed to identify the effect of the positive Indian Ocean Dipole (IOD) phenomenon on the spatial, temporal distribution of chlorophyll-a concentrations in the East Season in Padang Sea in 2019. The method used in this research was the Kriging analysis method applied in oceanographic parameter satellite imagery extraction point data. By applying the method, we produced the maps of the spatial distribution variation of chlorophyll-a content and Sea Surface Temperature (SST). The data of IOD events in 2019 showed the occurrence of a strong positive IOD phenomenon that caused anomaly in the Sea Surface Temperature (SST) in Padang Sea. The interpretation of Aqua-Modis level 2 satellite image data showed that the sea surface temperature during the East Season was relatively cold, which was in the minimum temperature ranging from 18.5-22°C with a normal temperature condition of 28-29°C. The minimum chlorophyll-a concentration in the East Season was 0.252 mg/m3; while the maximum value reached 18.5 mg/m3. The distribution value of chlorophyll-a concentration was 1.028 mg/m3.The RMSe Cross Validation value obtained was 0.504 for SST and 0.363 for chlorophyll-a with a mean SST of -0.0005 and mean chlorophyll-a of -0.0039.

Insight into intraspecific niche divergence and conservatism in American horseshoe crabs (Limulus polyphemus)

Limulus polyphemus is the sole extant representative of horseshoe crabs distributed along the Atlantic coast, and is threatened by human activities. Conservation priority to safeguard its habitat usually treats L. polyphemus as a whole, without consideration of different intraspecific ecological requirements. We seek to identify intraspecific ecological niche divergence or conservatism in L. polyphemus. In this study, ocean and coastal environmental conditions occupied by the six distinct metapopulations of L. polyphemus were collected, and compared using correlative approaches, niche overlaps among these six metapopulations were compared with geographical and genetic distances, the realized niche divergence/conservatism among these six metapopulations were tested, and ecological niche models were fitted for the six metapopulations separately and for L. polyphemus as a whole using state-of-the-art techniques. We found that mean sea surface temperature, tidal regime, chlorophyll a concentration, distance to shore and depth of seafloor were limiting factors in the geographic distribution of L. polyphemus. In addition to the former hypothesis that tidal amplitude and type account for the absence of L. polyphemus in the western Gulf of Mexico, our niche model predictions suggest that the narrow and high-depth seafloor in the western Gulf of Mexico also explain the absence. We found that realized niche overlaps among six metapopulations were not correlated with their geographic and genetic distances; rather the six metapopulations each occupied a unique combination of habitat conditions, showing different responses to environmental factors, although these divergences might be due a background effect. Results here showed that the distribution of one metapopulation of L. polyphemus cannot be inferred from changes in distribution of another, highlighting the inadequacy of one-size-fits-all conservation actions. We recommend that conservation priority assignment by IUCN and Natureserve for L. polyphemus would better consider the six metapopulations separately rather than L. polyphemus as a whole, which will deliver more useful information on guiding regional conservation efforts.