Sea Surface Temperature Range Research Articles

Spatial variability of jumbo flying squid (Dosidicus gigas) fishery related to remotely sensed SST and chlorophyll-a concentration (2004-2012)

An analysis was performed on the spatial distribution of the industrial Jumbo flying squid fishery within and outside the Peruvian exclusive economic zone (EEZ) in relation to sea surface temperature (SST) and chlorophyll-a (Chl-a). The locations of vessels were derived from the satellite tracking system (SISESAT) of the Instituto del Mar del Perú. Monthly environmental information came from the MODIS sensor of 4km spatial resolution for the period 2004–2012.Fishing operations data were divided into three periods based on their distance to shore consequential to the fishing regulations from January 2004 to October 2010, November 2010 to December 2011 and 2012. During the first period, two monthly patterns of spatial distribution were identified; from January to July fishing was along the coast from Paita (05°S) to San Juan de Marcona (15° 22′S) and later it was more concentrated in the northern area between Chimbote and Paita from August to December. In the second period, fishing operations formed small concentrations and widely dispersed points of fishing as a result of fishing restrictions within 80 nautical miles introduced in November 2010. In 2012 the fleet was located outside the EEZ. The highest concentrations of the fleet were found between 30 and 90 nautical miles offshore.The highest concentrations of squid were located from Paita-Chimbote (05°–09°S) and Callao–San Juan de Marcona (12° 03′–15° 22′S). Fishing operations were conducted in a wide range of SST between 14.1° and 26.8°C, with the highest incidence in temperatures between 18.4 to 22°C and with a tendency to be located more frequently in areas with higher temperatures in recent years. Regarding chlorophyll-a, the fleet fished between chlorophyll-a concentrations of 0–9.5mg/m3 within the EEZ, and from 0.2 to 0.5mg/m3 outside the EEZ. Distribution patterns of the fleet in relation to anomalies of sea surface temperature in the area El Niño 1+2, with respect to latitude and cyclic monthly SST variability, were also observed.

Parallelisms between sea surface temperature changes in the western tropical Atlantic (Guiana Basin) and high latitude climate signals over the last 140 000 years

Abstract. Sea surface temperatures (SST) in the Guiana Basin over the last 140 ka were obtained by measuring the C37 alkenone unsaturation index Uk'37 in the sediment core MD03-2616 (7° N, 53° W). The resulting data set is unique in the western tropical Atlantic region for this period. The SSTs range from 25.1 to 28.9 °C, i.e. glacial–interglacial amplitude of 3.8 °C, which is in the range of change of other tropical areas. During the last two interglacial stages (marine isotope stages; MIS1 and MIS5e) and warm long interstadials (MIS5d-a), a rapid transmission of climate variability from Arctic–tropical latitudes is recorded. During these periods, the MD03-2616 SSTs show a conspicuous parallelism with temperature changes observed in Greenland and SST records of North Atlantic mid-latitude cores (Iberian Margin 38° N, Martrat et al., 2007). The last deglaciation in the Guiana Basin is particularly revealing. MIS2 stands out as the coldest period of the interval analysed. The events recorded in Guiana parallel northern latitude events such as the Bølling–Allerød warming and the Younger Dryas cooling which ensued. These oscillations were previously documented in the δ18O of the Sajama tropical ice core (Bolivia) and are present in Guiana, with rates of ca. 6 °C ka−1 and changes of over 2 °C. During the glacial interval, significant abrupt variability is observed, e.g. oscillations of 0.5–1.2 °C during MIS3, which is about 30 % of the maximum glacial–interglacial SST change. In the MD03-2616 record, it is possible to unambiguously identify either the Dansgaard–Oeschger oscillations described in northern latitudes or the SST drops associated with the Heinrich events characteristic of North Atlantic records. Although these events form the background of the climate variability observed, what truly shapes SSTs in the Guiana Basin is a long-term tropical response to precessional changes, which is modulated in the opposite way to Northern Hemisphere variability. This lack of synchrony is consistent with other tropical records in locations to the north or south of the Guiana Basin and evidences an Arctic–tropical decoupling when a substantial reduction in the Atlantic meridional overturning circulation (AMOC) takes place.

Estimating the geographic range of a threatened shark in a data-poor region: Cetorhinus maximus in the South Atlantic Ocean

Abstract The distribution of the planktivorous basking shark Cetorhinus maximus is influenced by zooplankton abundance at small scales and temperature at medium scales in the North Atlantic. Here, we estimate the distribution of basking sharks on South Atlantic continental shelves, and the relative importance of chlorophyll concentration, as a proxy for zooplankton abundance, and temperature in determining habitat suitability for basking sharks at large scales. We used maximum entropy (MaxEnt) and maximum likelihood (MaxLike) species distribution modelling to test three hypotheses: the distribution of basking sharks is determined by (1) temperature, (2) chlorophyll concentration, or (3) both chlorophyll and temperature, while considering other factors, such as oxygen and salinity. Off South America, basking shark habitat included subtropical, temperate and cool-temperate waters between approximately 20°S and 55°S. Off Africa, basking shark habitat was limited to cool-temperate waters off Namibia and southern South Africa. MaxLike models had a better fit than MaxEnt models. The best model included minimum chlorophyll concentration, dissolved oxygen concentration, and sea surface temperature range, supporting hypothesis 3. However, of all variables included in the best model, minimum chlorophyll concentration had the highest influence on basking shark distribution. Unlike the North Atlantic distribution, the South Atlantic distribution of basking sharks includes subtropical and cool-temperate waters. This difference is explained by high minimum chlorophyll concentration off southern Brazil as compared to North Atlantic subtropical areas. Observations in other regions of the world support this conclusion. The highest habitat suitability for basking sharks is located close to nearshore areas that experience high anthropogenic impact.

Spatio-temporal dynamics in the location of the fishing grounds and catch per unit effort (CPUE) for Chilean jack mackerel (Trachurus murphyi Nichols, 1920) from Chinese trawl fleets on the high seas of the Southeast Pacific Ocean, 2001-2010

The decadal spatio-temporal distribution of the fishing effort and catch per unit effort (CPUE) for Chilean jack mackerel, Trachurus murphyi, stock are poorly understood. Data from the Chinese jack mackerel fleet was used to describe the location of the fishing effort and the relationship between standardized CPUE and sea surface temperatures (SST) during the period 2001–2010. A significant change in the spatio-temporal distribution of fishing effort and standardized CPUE was observed for jack mackerel during the study period. From January to March, the average CPUE was generally <15 tonnes (t) per net, except for 2007–2009. CPUE increased significantly during the autumn-winter (April to August), then gradually decreased in the spring and early summer (September to December). Average standardized CPUE in 2001–2005 was 23.3 t per net, but decreased to 19.7 t per net in 2006–2010. The change in the gravity center location of CPUE between months was similar during the primary fishing period (autumn to winter) in 2001–2006. After 2006, the pattern began to differ in July–October, which resulted in fishers spending more time to search for aggregations. A seasonal change was observed in the range of SSTs associated with high CPUE. Generally, the optimal SST range was from 13.0–15.0°C in autumn, 12.0–14.0°C in winter, 13–16°C in spring, and 15–19°C before 2006. However, a 1–2°C decrease in the optimal range in recent years was associated with a shift in the fishing grounds location to the southern area. In 2009, the optimal SST range was lower than in all other years. Taken together, the results suggest that a more thorough understanding of the seasonal or decadal relationship between SST and location of the fishing grounds is critical to improving the efficiency of the fishery and its management.

Variability of Suitable Habitat of Western Winter-Spring Cohort for Neon Flying Squid in the Northwest Pacific under Anomalous Environments.

We developed a habitat suitability index (HSI) model to evaluate the variability of suitable habitat for neon flying squid (Ommastrephes bartramii) under anomalous environments in the Northwest Pacific Ocean. Commercial fisheries data from the Chinese squid-jigging vessels on the traditional fishing ground bounded by 35°-45°N and 150°-175°E from July to November during 1998-2009 were used for analyses, as well as the environmental variables including sea surface temperature (SST), chlorophyll-a (Chl-a) concentration, sea surface height anomaly (SSHA) and sea surface salinity (SSS). Two empirical HSI models (arithmetic mean model, AMM; geometric mean model, GMM) were established according to the frequency distribution of fishing efforts. The AMM model was found to perform better than the GMM model. The AMM-based HSI model was further validated by the fishery and environmental data in 2010. The predicted HSI values in 1998 (high catch), 2008 (average catch) and 2009 (low catch) indicated that the squid habitat quality was strongly associated with the ENSO-induced variability in the oceanic conditions on the fishing ground. The La Niña events in 1998 tended to yield warm SST and favorable range of Chl-a concentration and SSHA, resulting in high-quality habitats for O. bartramii. While the fishing ground in the El Niño year of 2009 experienced anomalous cool waters and unfavorable range of Chl-a concentration and SSHA, leading to relatively low-quality squid habitats. Our findings suggest that the La Niña event in 1998 tended to result in more favorable habitats for O. bartramii in the Northwest Pacific with the gravity centers of fishing efforts falling within the defined suitable habitat and yielding high squid catch; whereas the El Niño event in 2009 yielded less favorable habitat areas with the fishing effort distribution mismatching the suitable habitat and a dramatic decline of the catch of O. bartramii. This study might provide some potentially valuable insights into exploring the relationship between the underlying squid habitat and the inter-annual environmental change.

Dynamical system properties of an axisymmetric convective tropical cyclone model

The dynamical system behaviour of tropical cyclones and their potential intensity with a view to sea surface temperature, tropospheric temperature stratification and tropospheric moisture content is investigated in the axisymmetric convective model HURMOD. The model results exhibit the existence of a fixed-point attractor associated with a strong tropical cyclone. Moreover, the initial vortex strength forms an amplitude threshold to cyclogenesis. Above this threshold, the size of the tropical cyclone and its intensity are independent of the initial vortex strength and its horizontal extent. Below the amplitude threshold, cyclogenesis does not occur and the system approaches an atmospheric state of rest. In case one allows for a deviation of the tropospheric stratification from moist-neutral conditions, the modelling results reveal the existence of bifurcations with the sea surface temperature representing the bifurcation parameter: As the sea surface temperature decreases and the storm weakens, the fixed-point attractor turns first into a limit cycle indicating a Hopf-bifurcation and then gives way to a steady-state of lower intensity, before the intensity oscillation becomes chaotic, and finally the tropical storm dies. The amplitude threshold and the sea surface temperature range, within which the system exhibits bifurcation points, are sensitive to the reference value of relative humidity and the reference tropospheric temperature stratification. If the reference troposphere is presumed to be moist-neutral, the dynamical behaviour of the modelled tropical cyclone does not change within the range of tropical sea surface temperature, and the tropical cyclone only slightly weakens with decreasing sea surface temperature, without any abrupt changes in intensity. Apart from the existence of Hopf-bifurcations, these findings are qualitatively similar to results gained from a low-order model presented in a precursory study.

El Niño–Southern Oscillation diversity and Southern Africa teleconnections during Austral Summer

A wide range of sea surface temperature (SST) expressions have been observed during the El Nino–Southern Oscillation events of 1950–2010, which have occurred simultaneously with different global atmospheric circulations. This study examines the atmospheric circulation and precipitation during December–March 1950–2010 over the African Continent south of 15 $$^{\circ }$$ S, a region hereafter known as Southern Africa, associated with eight tropical Pacific SST expressions characteristic of El Nino and La Nina events. The self-organizing map method along with a statistical distinguishability test was used to isolate the SST expressions of El Nino and La Nina. The seasonal precipitation forcing over Southern Africa associated with the eight SST expressions was investigated in terms of the horizontal winds, moisture budget and vertical motion. El Nino events, with warm SST across the east and central Pacific Ocean and warmer than average SST over the Indian Ocean, are associated with precipitation reductions over Southern Africa. The regional precipitation reductions are forced primarily by large-scale mid-tropospheric subsidence associated with anticyclonic circulation in the upper troposphere. El Nino events with cooler than average SST over the Indian Ocean are associated with precipitation increases over Southern Africa associated with lower tropospheric cyclonic circulation and mid-tropospheric ascent. La Nina events, with cool SST anomalies over the central Pacific and warm SST over the west Pacific and Indian Ocean, are associated with precipitation increases over Southern Africa. The regional precipitation increases are forced primarily by lower tropospheric cyclonic circulation, resulting in mid-tropospheric ascent and an increased flux of moisture into the region.

Sea surface temperature control on the distribution of far-traveled Southern Ocean ice-rafted detritus during the Pliocene

The flux and provenance of ice-rafted detritus (IRD) deposited in the Southern Ocean can reveal information about the past instability of Antarctica's ice sheets during different climatic conditions. Here we present a Pliocene IRD provenance record based on the 40Ar/39Ar ages of ice-rafted hornblende grains from Ocean Drilling Program Site 1165, located near Prydz Bay in the Indian Ocean sector of the Southern Ocean, along with the results of modeled sensitivity tests of iceberg trajectories and their spatial melting patterns under a range of sea surface temperatures (SSTs). Our provenance results reveal that IRD and hence icebergs in the Prydz Bay area were mainly sourced from (i) the local Prydz Bay region and (ii) the remote Wilkes Land margin located at the mouth of the low-lying Aurora Subglacial Basin. A series of IRD pulses, reaching up to 10 times background IRD flux levels, were previously identified at Site 1165 between 3.3 and 3.0 Ma. Our new results reveal that the average proportion of IRD sourced from distal Wilkes Land margin doubles after 3.3 Ma. Our iceberg trajectory-melting models show that slower iceberg melting under cooling SSTs over this middle Pliocene interval allowed Wilkes Land icebergs to travel farther before melting. Hence, declining SSTs can account for a large part of the observed IRD provenance record at Site 1165. In early Pliocene IRD layers, sampled at suborbital resolution around 4.6 Ma, we find evidence for significant increases in icebergs derived from Wilkes Land during very warm interglacials. This is suggestive of large-scale destabilization of the East Antarctic Ice Sheet in the Aurora Subglacial Basin, as far-traveled icebergs would have to overcome enhanced melting in warmer SSTs. Our results highlight the importance of considering SSTs when interpreting IRD flux and provenance records in distal locations.

Long-term variability of sea surface temperature in Taiwan Strait

Long-term variability of sea surface temperature (SST) in the Taiwan Strait was studied from the U.K. Met Office Hadley Centre climatological data set HadISST1. In 1957–2011, three epochs were identified. The first epoch of cooling SST lasted through 1976. The regime shift of 1976–1977 led to an extremely rapid warming of 2.1 °C in 22 years. Another regime shift occurred in 1998–1999, resulting in a 1.0 °C cooling by 2011. The cross-frontal gradient between the China Coastal Current and offshore Taiwan Strait waters has abruptly decreased in 1992 and remained low through 2011. The long-term warming of SST increased towards the East China Sea, where the SST warming in 1957–2011 was about three times that in the South China Sea. The long-term warming was strongly enhanced in winter, with the maximum warming of 3.8 °C in February. The wintertime amplification of long-term warming has resulted in a decrease of the north–south SST range from 5 to 4 °C and a decrease in the amplitude of seasonal cycle of SST from 11 to 8 °C.

Seasonal changes and controlling factors of sea surface pCO2 in the Yellow Sea

Sea surface partial pressure of carbon dioxide (pCO2) is an important parameter in the ocean carbon cycle system. By using accurate global sea surface pCO2 data, we can directly estimate the ratio of net CO2 uptake of global ocean, which can provide a support for further research of global carbon cycle. This article mainly discussed the seasonal changes of sea surface pCO2 and the relationships of pCO2 with sea surface temperature (SST) and chlorophyll-a concentration (Chla) in the Yellow Sea during winter, spring and summer, based on the data obtained by the shipboard measurements in February, May and August 2010. The results showed that the correlations of pCO2 with SST and Chla were different in different seasons. SST and pCO2 had a strong positive correlation in the range of higher SST for both spring and summer, and a relative weak correlation in winter, which can be fitted by a quadratic curve in each season. There was a linear correlation between pCO2 and Chla in each season. The data of pCO2 and Chla showed a negative correlation during winter and summer, and a positive one during spring. Based on the correlation analyses, we proposed a regression equation of pCO2 with SST and Chla as two parameters in the Yellow Sea for summer, which showed a root mean squared error (RMSE) of 16.68μatm when the shipboard-observed data were used. By using the satellite-observed SST and Chla instead of the field data, the RMSE of the result is 21.46μatm.

Fledging success of little auks in the high Arctic: do provisioning rates and the quality of foraging grounds matter?

Long-lived birds often face a dilemma between self-maintenance and reproduction. In order to maximize fitness, some seabird parents alternate short trips to collect food for offspring with long trips for self-feeding (bimodal foraging strategy). In this study, we examined whether temporal and spatial variation in the quality of foraging grounds affect provisioning and fledging success of a long-lived, bimodal forager, the little auk (Alle alle), the most abundant seabird species in the Arctic ecosystem. We predicted that an increase in sea surface temperature (SST), with an associated decrease in the preferred Arctic zooplankton prey, would increase foraging trip durations, decrease chick provisioning rates and decrease chick fledging success. Chick provisioning and survival were observed during three consecutive years (2008–2010) at two colonies with variable foraging conditions in Spitsbergen: Isfjorden and Magdalenefjorden. We found that a change in SST (range 1.6–5.4 °C) did not influence trip durations or provisioning rates. SST was, however, negatively correlated with the number of prey items delivered to a chick. Furthermore, provisioning rates did not influence chick’s probability to fledge; instead, SST was also negatively correlated with fledging probability. This was likely related to the prey availability and quality in the little auk’s foraging grounds. Our findings suggest that predicted warmer climate in the Arctic will negatively influence the ability of parents to provide their chicks, and consequently, the fledging prospects of little auk chicks.

Seychelles coral record of changes in sea surface temperature bimodality in the western Indian Ocean from the Mid-Holocene to the present

We report fossil coral records from the Seychelles comprising individual time slices of 14–20 sclerochronological years between 2 and 6.2 kyr BP to reconstruct changes in the seasonal cycle of western Indian Ocean sea surface temperature (SST) compared to the present (1990–2003). These reconstructions allowed us to link changes in the SST bimodality to orbital changes, which were causing a reorganization of the seasonal insolation pattern. Our results reveal the lowest seasonal SST range in the Mid-Holocene (6.2–5.2 kyr BP) and around 2 kyr BP, while the highest range is observed around 4.6 kyr BP and between 1990 and 2003. The season of maximum temperature shifts from austral spring (September to November) to austral autumn (March to May), following changes in seasonal insolation over the past 6 kyr. However, the changes in SST bimodality do not linearly follow the insolation seasonality. For example, the 5.2 and 6.2 kyr BP corals show only subtle SST differences in austral spring and autumn. We use paleoclimate simulations of a fully coupled atmosphere–ocean general circulation model to compare with proxy data for the Mid-Holocene around 6 kyr BP. The model results show that in the Mid-Holocene the austral winter and spring seasons in the western Indian Ocean were warmer while austral summer was cooler. This is qualitatively consistent with the coral data from 6.2 to 5.2 kyr BP, which shows a similar reduction in the seasonal amplitude compared to the present day. However, the pattern of the seasonal SST cycle in the model appears to follow the changes in insolation more directly than indicated by the corals. Our results highlight the importance of ocean–atmosphere interactions for Indian Ocean SST seasonality throughout the Holocene. In order to understand Holocene climate variability in the countries surrounding the Indian Ocean, we need a much more comprehensive analysis of seasonally resolved archives from the tropical Indian Ocean. Insolation data alone only provides an incomplete picture.

Multiyear CloudSat and CALIPSO Observations of the Dependence of Cloud Vertical Distribution on Sea Surface Temperature and Tropospheric Dynamics

AbstractUtilizing the synergy of the capabilities of CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and ~4.5 years of their observations, this paper investigates the dependence of the altitude distribution and thickness of tropical clouds on sea surface temperature (SST). Variations in the altitude distribution of clouds with SST show three distinct regimes: SST &amp;lt; 27.5°C, 27.5° &amp;lt; SST &amp;lt; 29°C, and SST &amp;gt; 29°C. At an SST &amp;lt; 27.5°C, the convection is rather weak, so that most of the clouds are limited to &amp;lt;2-km altitude with peak occurrence at 1–1.5 km. The frequency of occurrence of the low-altitude clouds as well as the prominence of the peak at ~1.5 km consistently decreases for SST &amp;gt; 24°C. Vertical development of clouds through the 3–12-km-altitude region increases for SST &amp;gt; 27.5°C to achieve maximum cloud occurrence and thickness in the SST range of 29°–30.5°C. Penetration of the deep convective clouds to altitudes &amp;gt;15 km and their frequency of occurrence increase with SST until ~30°C. These observations reveal two differences with the SST dependence of total cloudiness observed using passive imager data: (i) the increase in cloudiness at an SST &amp;gt; 26°–27°C observed using the imager data is found to be influenced by the increase in cirrus clouds generated by deep convective outflows and is not directly driven by the local SST, and (ii) the total cloudiness does not decrease for SST &amp;gt; 29.5°C as observed using imagers, but weakly increases until an SST of ~30.5°C. The role of the spatial gradient of SST and atmospheric dynamical parameters in modulating the observed SST dependence of cloudiness at different SST regimes is investigated.

Http://www.omicsonline.org/open-access/impacts-of-climate-change-on-agricultural-production-in-enugu-state-nigeria-2157-7617.1000234.php?aid=32633

Presently climate change is a serious problem on corals and their associated ecosystems that also affects the national and international income. The Present study emphasizes the impact of sea surface temperature on coral living, coral bleaching, coral growth and modelling for influential high temperature on corals as a significant biodiversity of tropical regions. Coral bleaching information, data of Sea Surface Temperature (SST), and coast watch utility software collected from the National Oceanic and Atmospheric Administration (NOAA) is an important way of monitoring and modelling of coral responses to SST. These data represent that the higher range of sea surface temperature and anomaly is responsible for the greater change of the coral bleaching area and hotspot. Within the narrow sea surface temperature change coral can respond significantly. This model finds southern pacific is most vulnerable and attractive sites for coral bleaching. Eastern tropical Pacific and Caribbean coral has been affected by El Nino and the anomaly of sea surface temperature. We need to continue to develop the models for protecting the coral reefs to present natural and anthropogenic climate change induced sea surface temperature causing the coral bleaching events.

Standardization of CPUE for Chilean jack mackerel (Trachurus murphyi) from Chinese trawl fleets in the high seas of the Southeast Pacific Ocean

The generalized linear model (GLM) and generalized additive model (GAM) were applied to the standardization of catch per unit effort (CPUE) for Chilean jack mackerel from Chinese factory trawl fishing fleets in the Southeast Pacific Ocean from 2001 to 2010 by removing the operational, environmental, spatial and temporal impacts. A total of 9 factors were selected to build the GLM and GAM, i.e., Year, Month, Vessel, La Nina and El Nino events (ELE), Latitude, Longitude, Sea surface temperature (SST), SST anomaly (SSTA), Nino3.4 index and an interaction term between Longitude and Latitude. The first 5 factors were significant components in the GLM, which in combination explained 27.34% of the total variance in nominal CPUE. In the stepwise GAM, all factors explained 30.78% of the total variance, with Month, Year and Vessel as the main factors influencing CPUE. The higher CPUE occurred during the period April to July at a SST range of 12–15°C and a SSTA range of 0.2–1.0°C. The CPUE was significantly higher in normal years compared with that in La Nina and El Nino years. The abundance of Chilean jack mackerel declined during 2001 and 2010, with an increase in 2007. This work provided the relative abundance index of Chilean jack mackerel for stock assessment by standardizing catch and effort data of Chinese trawl fisheries and examined the influence of temporal, spatial, environmental and fisheries operational factors on Chilean jack mackerel CPUE.

A Hybrid Cloud Detection Algorithm to Improve MODIS Sea Surface Temperature Data Quality and Coverage Over the Eastern Gulf of Mexico

Cloud contamination can lead to significant biases in sea surface temperature (SST) as estimated from satellite measurements. The effectiveness of four cloud detection algorithms for the Moderate Resolution Imaging Spectroradiometer (MODIS) in retaining valid SST data and masking cloud-contaminated data was assessed for all 2125 daytime and nighttime images during 2010 over the eastern Gulf of Mexico and including the east coast of Florida. None of the cloud detection algorithms was found to be sufficient to reliably differentiate clouds from valid SST, particularly during anomalously cold events. The strengths and weaknesses of each algorithm were identified, and a new hybrid cloud detection algorithm was developed to maximize valid data retention while excluding cloud-contaminated pixels. The hybrid algorithm was based on a decision tree, which includes a set of rules to use existing algorithms in different ways according to time and location. Comparing with >10000 concurrent in situ SST measurements from buoys, images processed with the hybrid algorithm showed increases in data capture and improved accuracy statistics over most existing algorithms. In particular, while keeping the same accuracy, the hybrid algorithm resulted in nearly 20% more SST retrievals than the most accurate algorithm (Quality SST) currently being used for operational processing. The increases in both data coverage and SST range should improve MODIS data products for more reliable SST retrievals in near real time, thus enhancing the ocean observing capacity to detect anomaly events and study short- and long-term SST changes in coastal environments.

Ecological modeling of the temperature dependence of cryptic species of planktonic Foraminifera in the Southern Hemisphere

Cryptic genetic species of planktonic Foraminifera often exhibit narrower biogeographic distributions and ecological preferences than the respective morphospecies. In theory, it should therefore be possible to improve the resolution of the paleoceanographic reconstructions based on sediment assemblages of these species. Here, we use observational data on the latitudinal distribution of 11 genotypes of Globigerina bulloides (including a newly described genotype), Orbulina universa, Truncorotalia truncatulinoides and Globoconella inflata in plankton tows from south Indian Ocean to model the relationship between their abundance and the sea surface temperature (SST). We then use this model to assess the potential benefit of knowing the ecological preferences of cryptic species on assemblage-based transfer functions. In doing so, we first apply this model to a database of assemblage counts in 1334 surface sediment samples from the Southern Hemisphere and simulate the expected abundances of individual genotypes in sediment samples. This simulated dataset is used to calibrate three different transfer functions: the Imbrie and Kipp Method, Weighted Averaging Partial Least Squares and Modern Analog Technique. Trials show that such simulated splitting of morphospecies into their respective genotypes leads to a substantial (7 to 25%) overall reduction of the error rates of SST estimates in the calibration dataset. The degree of error rate reduction is sensitive to the increase of taxonomic richness in the simulated assemblages induced by the co-occurrence of genotypes of the same morphospecies. Although the studied species occur across a broad SST range, the largest reduction of error rate by the transfer functions is obtained within the 4°C to 12°C SST range, where most of the studied genotypes are found. Our results show that all genotypes are not expected to improve the accuracy of transfer functions at the same level: while integrating cryptic diversity in G. bulloides, T. truncatulinoides and G. inflata clearly improve assemblage-based SST reconstructions, genotypes of O. universa have a negligible effect.

Comparison of the atmospheric forcing and oceanographic responses between the Labrador Sea and the Norwegian and Barents seas

A comparison of the mean conditions and variability in the climate and physical oceanographic characteristics between the Labrador Sea and surrounding shelves and the Norwegian and Barents seas is presented. The two regions are strongly advective systems being influenced by both cold, low saline flows from the Arctic and warm, high saline flows from the Atlantic. However, Arctic flows are more dominant in the Labrador Sea region, especially on the shelves, while Atlantic flows dominate in the Norwegian and a large part of the Barents Seas. In spite of this, the study reveals a general latitudinal dependence for several climate and oceanographic variables, including air temperatures, eastward winds, heat fluxes, and seasonal sea surface temperature range, within each of the two regions but with regional varying rates of change with latitude. We also confirm the previously reported out-of-phase relationships on interannual to decadal time scales of air and sea temperatures and sea-ice conditions between the Labrador Sea and the Norwegian and Barents seas regions from the 1950s until the mid-1990s. This is owing to their opposite response to the variability in the North Atlantic Oscillation (NAO). However, from the mid-1990s, air and sea temperatures in both regions generally have been in phase, showing strong warming and reduced ice coverage. The cause of this change is related to changes in the spatial structure of the atmospheric pressure patterns, resulting in a general reduction in the importance of NAO forcing over the North Atlantic.

Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

The semi-arid region of the Dead Sea heavily relies on groundwater resources. This dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management. Yet, information on groundwater discharge as one main component for a sustainable management varies significantly in this area. Moreover, discharge locations, volume and temporal variability are still only partly known. A multi-temporal thermal satellite approach is applied to localise and semi-quantitatively assess groundwater discharge along the entire coastline. The authors use 100 Landsat ETM + band 6.2 data, spanning the years between 2000 and 2011. In the first instance, raw data are transformed to sea surface temperature (SST). To account for groundwater intermittency and to provide a seasonally independent data set ∆T (maximum SST range) per-pixel within biennial periods is calculated subsequently. Groundwater affected areas (GAA) are characterised by ∆T 10 °C. This allows the exact identification of 37 discharge locations (clusters) along the entire Dead Sea coast, which spatially correspond to available in situ discharge observations. Tracking the GAA extents as a direct indicator of groundwater discharge volume over time reveals (1) a temporal variability correspondence between GAA extents and recharge amounts, (2) the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge, (3) a certain variability in discharge locations as a consequence of the Dead Sea level drop, and finally (4) the assumed flushing effect of old Dead Sea brines from the sedimentary body to have occurred at least during the two series of 2000–2001 and 2010–2011.

Early Paleogene temperature history of the Southwest Pacific Ocean: Reconciling proxies and models

We present a new multiproxy (TEX86, δ18O and Mg/Ca), marine temperature history for Canterbury Basin, eastern New Zealand, that extends from middle Paleocene to middle Eocene, including the Paleocene–Eocene thermal maximum (PETM) and early Eocene climatic optimum (EECO). In light of concerns that proxy-based sea surface temperature (SST) estimates are untenably warm for the southwest Pacific during the Eocene, we review the assumptions that underlie the proxies and develop a preliminary paleo-calibration for TEX86 that is based on four multiproxy Eocene records that represent an SST range of 15–34°C. For the southwest Pacific Paleogene, we show that TEX86L exhibits the best fit with the Eocene paleo-calibration. SSTs derived from related proxies (TEX86H, 1/TEX86) exhibit a systematic warm bias that increases as TEX86 values decrease (a warm bias of 4–7°C where TEX86<0.7). The TEX86L proxy indicates that southwest Pacific SST increased by ∼10°C from middle Paleocene to early Eocene, with SST maxima of 26–28°C (tropical) during the PETM and EECO and an SST minimum of 13–16°C (cool–warm temperate) at the middle/late Paleocene transition (58.7Ma). The base of the EECO is poorly defined in these records but the top is well-defined in Canterbury Basin by a 2–5°C decrease in SST and bottom water temperature (BWT) in the latest early Eocene (49.3Ma); BWT falls from a maximum of 18–20°C in the EECO to 12–14°C in the middle Eocene. Overall, cooler temperatures are recorded in the mid-Waipara section, which may reflect a deeper (∼500m water depth) and less neritic depositional setting compared with Hampden and ODP 1172 (∼200m water depth). The high SSTs and BWTs inferred for the PETM and EECO can be reconciled with Eocene coupled climate model results if the proxies are biased towards seasonal maxima and the likely effect of a proto-East Australian Current is taken into account.