The fate of a southwest Pacific bloom: gauging the impact of submesoscale vs. mesoscale circulation on biological  gradients in the subtropics

Abstract. The temporal evolution of a surface chlorophyll a bloom sampled in the western tropical South Pacific during the 2015 Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) cruise is examined. This region is usually characterized by largely oligotrophic conditions, i.e. low concentrations of inorganic nutrients at the surface and deep chlorophyll a maxima. Therefore, the presence of a surface bloom represents a significant perturbation from the mean ecological state. Combining in situ and remote sensing datasets, we characterize both the bloom's biogeochemical properties and the physical circulation responsible for structuring it. Biogeochemical observations of the bloom document the bloom itself, a subsequent decrease of surface chlorophyll a, significantly reduced surface phosphate concentrations relative to subtropical gyre water farther east, and a physical decoupling of chlorophyll a from a deep nitracline. All these characteristics are consistent with nitrogen fixation occurring within the bloom. The physical data suggest surface mesoscale circulation is the primary mechanism driving the bloom's advection, whereas balanced motions expected at submesoscales provide little contribution to observed flow. Together, the data provide a narrative where subtropical gyre water can produce significant chlorophyll a concentrations at the surface that is stirred, deformed, and transported great distances by the mesoscale circulation. In this case, for the time period considered, the transport is in an easterly direction, contrary to both the large-scale and mean mesoscale flow. As a result, future studies concerning surface production in the region need to take into account the role complex mesoscale structures play in redistributing subtropical gyre water.

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The Fate of a Southwest Pacific Bloom: Gauging the impact of submesoscale vs. mesoscale circulation on biological gradients in the subtropics

10.5194/bg-2017-84 ◽

2017 ◽

Cited By ~ 1

Author(s):

Alain de Verneil ◽

Louise Rousselet ◽

Andrea M. Doglioli ◽

Anne A. Petrenko ◽

Thierry Moutin

Keyword(s):

Chlorophyll A ◽

Large Scale ◽

Subtropical Gyre ◽

Mesoscale Circulation ◽

Mesoscale Structures ◽

Subsequent Decrease ◽

Time Period ◽

Low Concentrations ◽

The Impact

Abstract. The temporal evolution of a surface chlorophyll-a bloom sampled in the Western Tropical South Pacific during the 2015 Oligotrophy to UlTra-oligotrophy PACific Experiment cruise is examined. This region is usually characterized by largely oligotrophic conditions, ie low concentrations of inorganic nutrients at the surface and deep chlorophyll-a maxima. Therefore, the presence of a surface bloom represents a significant perturbation from the mean ecological state. Combining in situ and remote sensing datasets, we characterize both the bloom's biogeochemical properties as well as the physical circulation responsible for structuring it. Biogeochemical observations of the bloom document the bloom itself, a subsequent decrease of surface chlorophyll-a, significantly reduced surface phosphate concentrations relative to subtropical gyre water farther east, and a physical decoupling of chlorophyll-a from a deep nitracline. All these characteristics are consistent with nitrogen fixation occurring within the bloom. The physical data suggest surface mesoscale circulation is the primary mechanism driving the bloom’s advection, whereas balanced motions expected at submesoscales provide little contribution to observed flow. Together, the data provide a narrative where subtropical gyre water can produce significant chlorophyll-a concentrations at the surface that is stirred, deformed, and transported great distances by the mesoscale circulation. In this case, for the time period considered the transport is in an easterly direction, contrary to both the large-scale and mean mesoscale flow. As a result, future studies concerning surface production in the region need to take into account the role complex mesoscale structures play in redistributing subtropical gyre water.

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Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.838-841.705 ◽

2013 ◽

Vol 838-841 ◽

pp. 705-709

Author(s):

Yun Hao Yang ◽

Ren Kun Wang

Keyword(s):

Rock Mass ◽

Large Scale ◽

Damage Model ◽

Back Analysis ◽

In Situ Stress ◽

Surrounding Rock ◽

High In Situ Stress ◽

Underground Caverns ◽

The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

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What Is the Impact of Additional Tropical Observations on a Modern Data Assimilation System?

Monthly Weather Review ◽

10.1175/mwr-d-18-0120.1 ◽

2019 ◽

Vol 147 (7) ◽

pp. 2433-2449

Author(s):

Laura C. Slivinski ◽

Gilbert P. Compo ◽

Jeffrey S. Whitaker ◽

Prashant D. Sardeshmukh ◽

Jih-Wang A. Wang ◽

...

Keyword(s):

El Niño ◽

Large Scale ◽

El Nino ◽

Mean Square ◽

Observational Network ◽

In Situ Observations ◽

The Mean ◽

The Impact ◽

Assimilation System

Abstract Given the network of satellite and aircraft observations around the globe, do additional in situ observations impact analyses within a global forecast system? Despite the dense observational network at many levels in the tropical troposphere, assimilating additional sounding observations taken in the eastern tropical Pacific Ocean during the 2016 El Niño Rapid Response (ENRR) locally improves wind, temperature, and humidity 6-h forecasts using a modern assimilation system. Fields from a 50-km reanalysis that assimilates all available observations, including those taken during the ENRR, are compared with those from an otherwise-identical reanalysis that denies all ENRR observations. These observations reveal a bias in the 200-hPa divergence of the assimilating model during a strong El Niño. While the existing observational network partially corrects this bias, the ENRR observations provide a stronger mean correction in the analysis. Significant improvements in the mean-square fit of the first-guess fields to the assimilated ENRR observations demonstrate that they are valuable within the existing network. The effects of the ENRR observations are pronounced in levels of the troposphere that are sparsely observed, particularly 500–800 hPa. Assimilating ENRR observations has mixed effects on the mean-square difference with nearby non-ENRR observations. Using a similar system but with a higher-resolution forecast model yields comparable results to the lower-resolution system. These findings imply a limited improvement in large-scale forecast variability from additional in situ observations, but significant improvements in local 6-h forecasts.

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In Situ Observation of Stress Accumulation during Sub-Merged Arc Welding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.996.417 ◽

2014 ◽

Vol 996 ◽

pp. 417-423 ◽

Cited By ~ 1

Author(s):

Arne Kromm ◽

Thomas Kannengiesser

Keyword(s):

Arc Welding ◽

Large Scale ◽

X Ray Diffraction ◽

X Ray ◽

Residual Stress State ◽

Testing Facility ◽

Large Scale Testing ◽

The Impact ◽

Stress Accumulation

Results obtained from laboratory tests mostly need to be verified under fabrication conditions in order to incorporate design specifics (joint configuration and restraint), which effect the residual stress state considerably. For this purpose, multi-pass sub merged arc welding was performed in a special large-scale testing facility. The impact of varying interpass temperatures could be proven in-situ by means of a pronounced stress accumulation during welding and subsequent heat treatment accompanied by stress determination using X-ray diffraction.

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Heme b distributions through the Atlantic Ocean: in situ identification of iron limited phytoplankton

10.5194/egusphere-egu2020-15577 ◽

2020 ◽

Author(s):

Evangelia Louropoulou ◽

Martha Gledhill ◽

Eric P. Achterberg ◽

Thomas J. Browning ◽

David J. Honey ◽

...

Keyword(s):

Atlantic Ocean ◽

Large Scale ◽

North Atlantic Ocean ◽

Iron Status ◽

Mean Value ◽

Particulate Material ◽

South Atlantic ◽

Phytoplankton Communities ◽

The Impact

Heme b is an iron-containing cofactor in hemoproteins that participates in the fundamental processes of photosynthesis and respiration in phytoplankton. Heme b concentrations typically decline in waters with low iron concentrations but due to lack of field data, the distribution of heme b in particulate material in the ocean is poorly constrained. Within the framework of the Helmholtz Research School for Ocean System Science and Technology (HOSST) and the GEOTRACES programme, the authors compiled datasets and conducted multidisciplinary research (e.g. chemical oceanography, microbiology, biogeochemical modelling) in order to test heme b as an indicator of in situ iron-limited phytoplankton. This study was initiated in the North Atlantic Ocean and expanded to the under-sampled South Atlantic Ocean for comparison of the results considering the different phytoplankton populations. Here, we report particulate heme b distributions across the Atlantic Ocean (59.9&#176;N to 34.6&#176;S). Heme b concentrations in surface waters ranged from 0.10 to 33.7 pmol L-1 (median=1.47 pmol L-1, n=974) and were highest in regions with a high biomass. The ratio of heme b to particulate organic carbon (POC) exhibited a mean value of 0.44 &#956;mol heme b mol-1 POC. We identified the ratio of 0.10 &#181;mol heme b mol-1 POC as the cut-off between heme b replete and heme b deficient phytoplankton. By this definition, the ratio heme b relative to POC was consistently below 0.10 &#956;mol mol-1 in areas characterized by low Fe supply; these were the Subtropical South Atlantic gyre and the seasonally iron limited Irminger Basin. Thus, the ratio heme b relative to POC gave a reliable indication of iron limited phytoplankton communities in situ. Furthermore, the comparison of observed and modelled heme b suggested that heme b could account for between 0.17-9.1% of biogenic iron. This range was comparable to previous culturing observations for species with low heme b content and species growing in low Fe (&#8804;0.50 nmol L-1) or nitrate culturing media. Our large scale observations of heme b relative to organic matter suggest the impact of changes in iron supply on phytoplankton iron status.

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The impact of two Chaoborus species on a zooplankton community

Canadian Journal of Zoology ◽

10.1139/z90-141 ◽

1990 ◽

Vol 68 (5) ◽

pp. 981-985 ◽

Cited By ~ 18

Author(s):

Neil A. MacKay ◽

Stephen R. Carpenter ◽

Patricia A. Soranno ◽

Michael J. Vanni

Keyword(s):

Chlorophyll A ◽

Daphnia Pulex ◽

Zooplankton Community ◽

Chlorophyll A Concentration ◽

Chaoborus Flavicans ◽

Chaoborus Americanus ◽

Diaptomus Oregonensis ◽

Herbivore Responses ◽

The Impact

The responses of a zooplankton community to Chaoborus predation were studied in large in situ mesocosms in Peter Lake. Chaoborus flavicans, the native chaoborid, significantly reduced the density of the dominant grazer, Daphnia pulex, in relation to controls that lacked Chaoborus. Chaoborus americanus, a species found only in fishless bogs, reduced Da. pulex densities far more than the chaoborid found in Peter Lake, C. flavicans. Chaoborus americanus also significantly reduced the dominant copepod, Diaptomus oregonensis, in relation to both the control and the C. flavicans treatment. Chlorophyll a concentration did not differ among treatments, indicating that herbivore responses could not be explained by changes in food levels. Our results show that Chaoborus predation can greatly affect a zooplankton community, especially daphnids.

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Key factors affecting people’s unwillingness to be confined during the COVID-19 pandemic in Spain: a large-scale population study

Scientific Reports ◽

10.1038/s41598-021-97645-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marina Martinez-Garcia ◽

Alejandro Rabasa ◽

Xavier Barber ◽

Kristina Polotskaya ◽

Kristof Roomp ◽

...

Keyword(s):

Large Scale ◽

Psychological Impact ◽

Important Variable ◽

Policy Makers ◽

Factors Affecting ◽

Time Period ◽

Economic Support ◽

Gender And Age ◽

Scale Population ◽

The Impact

AbstractPopulation confinements have been one of the most widely adopted non-pharmaceutical interventions (NPIs) implemented by governments across the globe to help contain the spread of the SARS-CoV-2 virus. While confinement measures have been proven to be effective to reduce the number of infections, they entail significant economic and social costs. Thus, different policy makers and social groups have exhibited varying levels of acceptance of this type of measures. In this context, understanding the factors that determine the willingness of individuals to be confined during a pandemic is of paramount importance, particularly, to policy and decision-makers. In this paper, we study the factors that influence the unwillingness to be confined during the COVID-19 pandemic by the means of a large-scale, online population survey deployed in Spain. We perform two types of analyses (logistic regression and automatic pattern discovery) and consider socio-demographic, economic and psychological factors, together with the 14-day cumulative incidence per 100,000 inhabitants. Our analysis of 109,515 answers to the survey covers data spanning over a 5-month time period to shed light on the impact of the passage of time. We find evidence of pandemic fatigue as the percentage of those who report an unwillingness to be in confinement increases over time; we identify significant gender differences, with women being generally less likely than men to be able to sustain long-term confinement of at least 6 months; we uncover that the psychological impact was the most important factor to determine the willingness to be in confinement at the beginning of the pandemic, to be replaced by the economic impact as the most important variable towards the end of our period of study. Our results highlight the need to design gender and age specific public policies, to implement psychological and economic support programs and to address the evident pandemic fatigue as the success of potential future confinements will depend on the population’s willingness to comply with them.

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Yet another lockdown? A large-scale study on people's unwillingness to be confined during the first 5 months of the COVID-19 pandemic in Spain

10.1101/2021.05.08.21256792 ◽

2021 ◽

Author(s):

Marina Martinez-Garcia ◽

Alejandro Rabasa ◽

Xavier Barber ◽

Kristina Polotskaya ◽

Kristof Roomp ◽

...

Keyword(s):

Large Scale ◽

Psychological Impact ◽

Important Variable ◽

Decision Makers ◽

Policy Makers ◽

Time Period ◽

Economic Support ◽

Gender And Age ◽

The Impact

Population confinements have been one of the most widely adopted non-pharmaceutical interventions (NPIs) implemented by governments across the globe to help contain the spread of the SARS-CoV-2 virus. While confinement measures have been proven to be effective to reduce the number of infections, they entail significant economic and social costs. Thus, different policy makers and social groups have exhibited varying levels of acceptance of this type of measures. In this context, understanding the factors that determine the willingness of individuals to be confined during a pandemic is of paramount importance, particularly, to policy and decision-makers. In this paper, we study the factors that influence the unwillingness to be confined during the COVID-19 pandemic by means of a large-scale, online population survey deployed in Spain. We apply both quantitative (logistic regression) and qualitative (automatic pattern discovery) methods and consider socio-demographic, economic and psychological factors, together with the 14-day cumulative incidence per 100,000 inhabitants. Our analysis of 109,515 answers to the survey covers data spanning over a 5-month time period to shed light on the impact of the passage of time. We find evidence of pandemic fatigue as the percentage of those who report an unwillingness to be in confinement increases over time; we identify significant gender differences, with women being generally less likely than men to be able to sustain long-term confinement of at least 6 months; we uncover that the psychological impact was the most important factor to determine the willingness to be in confinement at the beginning of the pandemic, to be replaced by the economic impact as the most important variable towards the end of our period of study. Our results highlight the need to design gender and age specific public policies, to implement psychological and economic support programs and to address the evident pandemic fatigue as the success of potential future confinements will depend on the population's willingness to comply with them.

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Investigating the Large-Scale Transport of a Volcanic Plume and the Impact on a Secondary Site

Atmosphere ◽

10.3390/atmos11050548 ◽

2020 ◽

Vol 11 (5) ◽

pp. 548 ◽

Cited By ~ 1

Author(s):

David Jean Du Preez ◽

Hassan Bencherif ◽

Nelson Bègue ◽

Lieven Clarisse ◽

Rebecca F. Hoffman ◽

...

Keyword(s):

Large Scale ◽

Dispersion Model ◽

Secondary Site ◽

Volcanic Plume ◽

Volcanic Complex ◽

Solar Ultraviolet Radiation ◽

Volcanic Plumes ◽

Low Concentrations ◽

The Impact ◽

Good Agreement

Volcanic plumes can be transported across vast distances and can have an impact on solar ultraviolet radiation (UVR) reaching the surface due to the scattering and absorption caused by aerosols. The dispersion of the volcanic plume from the Puyehue-Cordón Caulle volcanic complex (PCCVC) eruption was investigated to determine the effect on aerosol loading at Cape Point, South Africa. The eruption occurred on 4 June 2011 and resulted in a plume reaching a height of between 9 and 12 km and was dispersed across the Southern Hemisphere. Satellite sulphur dioxide (SO2) observations and a dispersion model showed low concentrations of SO2 at the secondary site. However, satellite observations of volcanic ash and ground-based aerosol measurements did show increases between 10 and 20 June 2011 at the secondary site. Furthermore, there was good agreement with the dispersion model results and observations from satellites with most of the plume located between latitudes 40°–60° South.

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Limnology of shallow lakes of the semi-arid Central Pampa of Argentina

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x4817 ◽

2019 ◽

Vol 31 ◽

Author(s):

Santiago Andrés Echaniz ◽

Alicia María Vignatti

Keyword(s):

Chlorophyll A ◽

Fish Fauna ◽

Chemical Diversity ◽

Nutrient Concentrations ◽

Urban Sewage ◽

Low Salinity ◽

Low Concentrations ◽

High Concentrations ◽

Physical And Chemical

Abstract Aim The Central Pampa of Argentina has three recognized phytogeographic regions that arise due to the decrease in rainfall towards the west. The area has numerous lakes that are mainly temporary, with hydroperiods that relate to climatic cycles, although some of them have changed due to anthropogenic influence. Some of these lakes have been studied with special reference to zooplankton, but information on their physical and chemical aspects is scarce. Consequently, managing and evaluating the anthropogenic effects on these ecosystems is challenging. The objective of this study was to explore the limnological characteristics of lakes in different regions in the Central Pampa that experience different anthropic influences. Methods Ten lakes were sampled seasonally (January, April, July, and October) during 2007. In situ measurements included transparency, pH, temperature, and dissolved oxygen concentration, and 2-L water samples were collected to determine salinity, ion composition, suspended solids, nutrient concentration, and phytoplankton chlorophyll- a concentration. Results Salinity ranged from 0.32-136.72 g L-1, with Na+ being the dominant ion in nine lakes and Cl- and HCO3- predominating in the higher- and lower-salinity lakes respectively. Nutrient concentrations were high (total Kjeldahl nitrogen: 7.97-34.69 mg L-1; total phosphorous: 4.07-14.82 mg L-1), and all lakes were hypertrophic. We determined three lake classes: i) lakes transformed from low-salinity lakes into hypersaline ones through human inactivation of the fluvial system that fed it; ii) mesosaline temporary lakes lacking fish, with low concentrations of chlorophyll-a and influenced by agricultural activities, and iii) subsaline and hyposaline lakes, highly modified by urban sewage, converted in permanent lakes (which allowed fish fauna development) and with reduced water transparency (due to high concentrations of phytoplankton chlorophyll-a). Conclusions The chemical diversity of the studied lakes is low, and their predominance of Na+ and Cl- indicated that evaporation and crystallization control the water chemistry. Additionally, this study showed the consequences of the anthropic impact, which alter water chemical composition, trophic structure and, thus, the ecological characteristics of lakes.

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