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833 result(s) for "Gruber, N."
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Imprint of Southern Ocean eddies on winds, clouds and rainfall
Owing to the turbulent nature of the ocean, mesoscale eddies are omnipresent. An analysis of atmospheric conditions associated with several hundred thousand eddies in the Southern Ocean suggests that the transitory sea surface temperature fronts associated with these eddies alter near-surface winds, clouds and rainfall. Owing to the turbulent nature of the ocean, mesoscale eddies are omnipresent. The impact of these transitory and approximately circular sea surface temperature fronts on the overlying atmosphere is not well known. Stationary fronts such as the Gulf Stream have been reported to lead to pronounced atmospheric changes 1 , 2 . However, the impact of transient ocean eddies on the atmosphere has not been determined systematically, except on winds and to some extent clouds 3 , 4 , 5 , 6 . Here, we examine the atmospheric conditions associated with over 600,000 individual eddies in the Southern Ocean, using satellite data. We show that ocean eddies locally affect near-surface wind, cloud properties and rainfall. The observed pattern of atmospheric change is consistent with a mechanism in which sea surface temperature anomalies associated with the oceanic eddies modify turbulence in the atmospheric boundary layer. In the case of cyclonic eddies, this modification triggers a slackening of near-surface winds, a decline in cloud fraction and water content, and a reduction in rainfall. We conclude that transient mesoscale ocean structures can significantly affect much larger atmospheric low-pressure systems that swiftly pass by at the latitudes investigated.
Oxygen trends over five decades in the North Atlantic
We investigate long‐term trends in dissolved oxygen in the North Atlantic from 1960 to 2009 on the basis of a newly assembled high‐quality dataset consisting of oxygen data from three different sources: CARINA, GLODAP and the World Ocean Database. Oxygen trends are determined along isopycnal surfaces for eight regions and five water masses using a general least‐squares linear regression method that accounts for temporal auto‐correlation. Our results show a significant decrease of oxygen in the Upper (UW), Mode (MW) and Intermediate (IW) waters in almost all regions over the last 5 decades. Over the same period, oxygen increased in the Lower Intermediate Water (LIW) and Labrador Sea Water (LSW) throughout the North Atlantic. The observed oxygen decreases in the MW and IW of the northern and eastern regions are largely driven by changes in circulation and/or ventilation, while changes in solubility are the main driver for the oxygen decrease in the UW and the increases in the LIW and LSW. From 1960 until 2009 the UW, MW, and IW horizons have lost a total of −57 ± 34 Tmol, while the LIW and LSW horizons have gained 46 ± 47 Tmol, integrating to a roughly constant oxygen inventory in the North Atlantic. Comparing our oxygen trends with those of the oceanic heat content, we find an O2 to heat change ratio of −3.6 ± 2.8 nmol J−1 for the UW, MW and IW, and a ratio of −2.8 ± 3.4 nmol J−1 for the LIW and LSW. These ratios are substantially larger than those expected from solubility alone. Key Points O2 changes significantly over the last five decades in the North Atlantic The upper ocean has lost O2, while the lower waters have gained O2 O2/heat change ratio is larger than that expected from solubility
Drivers and uncertainties of future global marine primary production in marine ecosystem models
Past model studies have projected a global decrease in marine net primary production (NPP) over the 21st century, but these studies focused on the multi-model mean rather than on the large inter-model differences. Here, we analyze model-simulated changes in NPP for the 21st century under IPCC's high-emission scenario RCP8.5. We use a suite of nine coupled carbon–climate Earth system models with embedded marine ecosystem models and focus on the spread between the different models and the underlying reasons. Globally, NPP decreases in five out of the nine models over the course of the 21st century, while three show no significant trend and one even simulates an increase. The largest model spread occurs in the low latitudes (between 30° S and 30° N), with individual models simulating relative changes between −25 and +40 %. Of the seven models diagnosing a net decrease in NPP in the low latitudes, only three simulate this to be a consequence of the classical interpretation, i.e., a stronger nutrient limitation due to increased stratification leading to reduced phytoplankton growth. In the other four, warming-induced increases in phytoplankton growth outbalance the stronger nutrient limitation. However, temperature-driven increases in grazing and other loss processes cause a net decrease in phytoplankton biomass and reduce NPP despite higher growth rates. One model projects a strong increase in NPP in the low latitudes, caused by an intensification of the microbial loop, while NPP in the remaining model changes by less than 0.5 %. While models consistently project increases NPP in the Southern Ocean, the regional inter-model range is also very substantial. In most models, this increase in NPP is driven by temperature, but it is also modulated by changes in light, macronutrients and iron as well as grazing. Overall, current projections of future changes in global marine NPP are subject to large uncertainties and necessitate a dedicated and sustained effort to improve the models and the concepts and data that guide their development.
Trends and drivers in global surface ocean pH over the past 3 decades
We report global long-term trends in surface ocean pH using a new pH data set computed by combining fCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981–2011 and 1991–2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a mean rate of decrease of 0.0018 ± 0.0004 yr−1 for 1991–2011. We are not able to calculate a global trend for 1981–2011 because too few biomes have enough data for this. In half the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean CO2 chemistry remaining in a transient equilibrium with the increase in atmospheric CO2. In the remaining biomes, deviations from such equilibrium may reflect that the trend of surface ocean fCO2 is not equal to that of the atmosphere, most notably in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.
Mesoscale atmosphere ocean coupling enhances the transfer of wind energy into the ocean
Although it is well established that the large-scale wind drives much of the world’s ocean circulation, the contribution of the wind energy input at mesoscales (10–200 km) remains poorly known. Here we use regional simulations with a coupled high-resolution atmosphere–ocean model of the South Atlantic, to show that mesoscale ocean features and, in particular, eddies can be energized by their thermodynamic interactions with the atmosphere. Owing to their sea-surface temperature anomalies affecting the wind field above them, the oceanic eddies in the presence of a large-scale wind gradient provide a mesoscale conduit for the transfer of energy into the ocean. Our simulations show that this pathway is responsible for up to 10% of the kinetic energy of the oceanic mesoscale eddy field in the South Atlantic. The conditions for this pathway to inject energy directly into the mesoscale prevail over much of the Southern Ocean north of the Polar Front. The precise mechanism for wind energy input into the ocean at mesoscales remains uncertain. Here, using a high-resolution atmosphere-ocean model of the South Atlantic, the authors show that a mesoscale conduit associated with oceanic eddies is responsible for up to 10% of kinetic energy transfer.
Global ocean storage of anthropogenic carbon
The global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data-based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air–sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on forward ocean models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a \"best\" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 ± 31 PgC (±20% uncertainty). This estimate includes a broad range of values, suggesting that a combination of approaches is necessary in order to achieve a robust quantification of the ocean sink of anthropogenic CO2.
Data-based estimates of the ocean carbon sink variability – first results of the Surface Ocean pCO2 Mapping intercomparison (SOCOM)
Using measurements of the surface-ocean CO2 partial pressure (pCO2) and 14 different pCO2 mapping methods recently collated by the Surface Ocean pCO2 Mapping intercomparison (SOCOM) initiative, variations in regional and global sea–air CO2 fluxes are investigated. Though the available mapping methods use widely different approaches, we find relatively consistent estimates of regional pCO2 seasonality, in line with previous estimates. In terms of interannual variability (IAV), all mapping methods estimate the largest variations to occur in the eastern equatorial Pacific. Despite considerable spread in the detailed variations, mapping methods that fit the data more closely also tend to agree more closely with each other in regional averages. Encouragingly, this includes mapping methods belonging to complementary types – taking variability either directly from the pCO2 data or indirectly from driver data via regression. From a weighted ensemble average, we find an IAV amplitude of the global sea–air CO2 flux of 0.31 PgC yr-1 (standard deviation over 1992–2009), which is larger than simulated by biogeochemical process models. From a decadal perspective, the global ocean CO2 uptake is estimated to have gradually increased since about 2000, with little decadal change prior to that. The weighted mean net global ocean CO2 sink estimated by the SOCOM ensemble is -1.75 PgC yr-1 (1992–2009), consistent within uncertainties with estimates from ocean-interior carbon data or atmospheric oxygen trends.
Problem focused coping strategies and high self-compassion can be seen as protective factors to lower stress, negative emotional reactions to job and anxiety
IntroductionPrevious research has shown that:- problem focused coping strategies aim to change the reaction to the stressful situations- self-compassion may reduce anxiety and depression. It is associated with happiness, it increases with age, it is negatively correlated with perceived stress and in older adults seems to be associated with higher levels of wisdom, integration, acceptance of one’s past life experiences and higher levels of meaning in life.- job related low LPLA (Low pleasurable Low arousal emotions) and high LPHA (Low pleasurable High arousal emotions) levels corelate to depression, anxiety, and stress.ObjectivesCase report of 60 years old computer scientistMethodsPsychiatric interview and scales:Self-reported questionnaires: The Brief-COPE, The Self-Compassion Scale (SCS-SF), The Perceived Stress Scale (PSS 10), The Depression Anxiety Stress Scale (DASS-10), The Job-related Affective Well-being Scale (JAWS), The Subjective Happiness Scale (SHS), The Meaning in Life Questionnaire (MLQ)Results60 years old male computer scientist, single, without children, multiple times a week in recreative activities and physical activities. He is not satisfied with close friendships, he sleeps 6 hours in day, he didn’t have traumatic experiences in life. He is not religious. He works 45 hours per week, from that 5-10 hours weekly works at the site of primary employment.The Brief-COPE: High score for using problem focused coping strategies-acceptance, planning, positive reframing, and informational support. Maladaptive coping strategies used in lower grade: self-blame and self-distraction.SCS-SF: Much higher levels of self-compassion than the norms established by previous research.DASS-10:low.SHS: lower happiness level than the norms established by previous research.JAWS: High negative emotional reactions to job and low level of overall job-related affective wellbeing together with lower HPHA, higher LPHA, and lower LPLA in comparison to previous research. According to previous research this person is not satisfied with his job and have a lot of negative emotions regarding his job.PSS 10: Levels of perceived stress are lower than the norms established by previous research.MLQ: this person scored below 24 on the scale- presence of meaning and below 24 on the scale search for meaning. According to previous research person with this score do not feel their life has a valued meaning and purpose and they do not not actively explore that meaning or seeking meaning.ConclusionsProblem focused coping strategies and high self-compassion can be seen as protective factors to lower stress, negative emotional reactions to job and anxietyDisclosure of InterestNone Declared
A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink
The Atlantic Ocean is one of the most important sinks for atmospheric carbon dioxide (CO2), but this sink has been shown to vary substantially in time. Here we use surface ocean CO2 observations to estimate this sink and the temporal variability from 1998 through 2007 in the Atlantic Ocean. We benefit from (i) a continuous improvement of the observations, i.e. the Surface Ocean CO2 Atlas (SOCAT) v1.5 database and (ii) a newly developed technique to interpolate the observations in space and time. In particular, we use a two-step neural network approach to reconstruct basin-wide monthly maps of the sea surface partial pressure of CO2 (pCO2) at a resolution of 1° × 1°. From those, we compute the air–sea CO2 flux maps using a standard gas exchange parameterization and high-resolution wind speeds. The neural networks fit the observed pCO2 data with a root mean square error (RMSE) of about 10 μatm and with almost no bias. A check against independent time-series data and new data from SOCAT v2 reveals a larger RMSE of 22.8 μatm for the entire Atlantic Ocean, which decreases to 16.3 μatm for data south of 40° N. We estimate a decadal mean uptake flux of −0.45 ± 0.15 Pg C yr−1 for the Atlantic between 44° S and 79° N, representing the sum of a strong uptake north of 18° N (−0.39 ± 0.10 Pg C yr−1), outgassing in the tropics (18° S–18° N, 0.11 ± 0.07 Pg C yr−1), and uptake in the subtropical/temperate South Atlantic south of 18° S (−0.16 ± 0.06 Pg C yr−1), consistent with recent studies. The strongest seasonal variability of the CO2 flux occurs in the temperature-driven subtropical North Atlantic, with uptake in winter and outgassing in summer. The seasonal cycle is antiphased in the subpolar latitudes relative to the subtropics largely as a result of the biologically driven winter-to-summer drawdown of CO2. Over the 10 yr analysis period (1998 through 2007), sea surface pCO2 increased faster than that of the atmosphere in large areas poleward of 40° N, while in other regions of the North Atlantic the sea surface pCO2 increased at a slower rate, resulting in a barely changing Atlantic carbon sink north of the Equator (−0.01 ± 0.02 Pg C yr−1 decade−1). Surface ocean pCO2 increased at a slower rate relative to atmospheric CO2 over most of the Atlantic south of the Equator, leading to a substantial trend toward a stronger CO2 sink for the entire South Atlantic (−0.14 ± 0.02 Pg C yr−1 decade−1). In contrast to the 10 yr trends, the Atlantic Ocean carbon sink varies relatively little on inter-annual timescales (±0.04 Pg C yr−1; 1 σ).
Changing controls on oceanic radiocarbon: New insights on shallow-to-deep ocean exchange and anthropogenic CO2 uptake
The injection of radiocarbon (14C) into the atmosphere by nuclear weapons testing in the 1950s and 1960s has provided a powerful tracer to investigate ocean physical and chemical processes. While the oceanic uptake of bomb‐derived 14C was primarily controlled by air‐sea exchange in the early decades after the bomb spike, we demonstrate that changes in oceanic 14C are now primarily controlled by shallow‐to‐deep ocean exchange, i.e., the same mechanism that governs anthropogenic CO2 uptake. This is a result of accumulated bomb 14C uptake that has rapidly decreased the air‐sea gradient of 14C/C (Δ14C) and shifted the main reservoir of bomb 14C from the atmosphere to the upper ocean. The air‐sea Δ14C gradient, reduced further by fossil fuel dilution, is now weaker than before weapons testing in most regions. Oceanic 14C, and particularly its temporal change, can now be used to study the oceanic uptake of anthropogenic CO2. We examine observed changes in oceanic Δ14C between the WOCE/SAVE (1988–1995) and the CLIVAR (2001–2007) eras and simulations with two ocean general circulation models, the Community Climate System Model (CCSM) and the Estimating the Circulation and Climate of the Ocean Model (ECCO). Observed oceanic Δ14C and its changes between the 1980s–90s and 2000s indicate that shallow‐to‐deep exchange is too efficient in ECCO and too sluggish in CCSM. These findings suggest that mean global oceanic uptake of anthropogenic CO2 between 1990 and 2007 is bounded by the ECCO‐based estimate of 2.3 Pg C yr−1 and the CCSM‐based estimate of 1.7 Pg C yr−1. Key Points Interior ocean processes are now the main influence on oceanic radiocarbon Oceanic radiocarbon can now be used to evaluate ocean models at global scales 14C data suggest the ocean CO2 sink is between 1.7 and 2.3 PgC/yr for 1990‐2007