We present results from a new, global, high-resolution (∼3-km for ocean and ∼6-km for atmosphere) realistic earth system simulation. This simulation allows us to examine aspects of small-scale ...air-sea interaction beyond what previous studies have reported. Our study focuses on recurring intermittent wind events in the Gulf Stream region. These events induce local air-sea heat fluxes above Sea Surface Temperature (SST) anomalies with horizontal scales smaller than 500km. In particular, strong latent heat bursts above warm SST anomalies are observed during these wind events. We show that such wind events are associated with a secondary circulation that acts to fuel the latent heat bursts by transferring dry air and momentum down to the surface. The intensity of this secondary circulation is related to the strength of small-scale SST fronts that border SST anomalies. The study of such phenomena requires high-resolution in both the atmospheric and oceanic components of the model.
Abstract The Arctic seasonal halocline impacts the exchange of heat, energy, and nutrients between the surface and the deeper ocean, and it is changing in response to Arctic sea ice melt over the ...past several decades. Here, we assess seasonal halocline formation in 1975 and 2006–12 by comparing daily, May–September, salinity profiles collected in the Canada Basin under sea ice. We evaluate differences between the two time periods using a one-dimensional (1D) bulk model to quantify differences in freshwater input and vertical mixing. The 1D metrics indicate that two separate factors contribute similarly to stronger stratification in 2006–12 relative to 1975: 1) larger surface freshwater input and 2) less vertical mixing of that freshwater. The larger freshwater input is mainly important in August–September, consistent with a longer melt season in recent years. The reduced vertical mixing is mainly important from June until mid-August, when similar levels of freshwater input in 1975 and 2006–12 are mixed over a different depth range, resulting in different stratification. These results imply that decadal changes to ice–ocean dynamics, in addition to freshwater input, significantly contribute to the stronger seasonal stratification in 2006–12 relative to 1975. These findings highlight the need for near-surface process studies to elucidate the impact of lateral processes and ice–ocean momentum exchange on vertical mixing. Moreover, the results may provide insight for improving the representation of decadal changes to Arctic upper-ocean stratification in climate models that do not capture decadal changes to vertical mixing.
Quantifying the pathways of fixed nitrogen (N) loss in marine oxygen deficient zones (ODZs) and the isotopic fractionation caused by these processes are important for understanding the marine fixed N ...budget and its potential for change. In this study, a variety of approaches were used to quantify fixed N loss in the eastern tropical South Pacific Ocean (ETSP). The required measurements included nutrient concentration (nitrate—NO3-, nitrite—NO2-, and phosphate—PO43-), gas ratio (N2/Ar) measurements, and stable N and O isotopes in NO3-, NO2-, and nitrogen gas (N2). The dissolved inorganic nitrogen deficit calculated from PO43- (DINdef,P) exceeded the concentration of N2 gas biologically produced in the ODZ (local N2bio) throughout the ODZ at most stations, likely due to release of PO43- from sediments driving up DINdef,P. Calculating DIN deficit using water mass analysis and local oxygen (O2) consumption (DINdef,OMP) yielded better agreement with local N2bio than DINdef,P, except at the maximum N2bio, where DINdef,OMP misses contributions of anaerobic ammonia oxidation (anammox) to N2 production. We used the mismatch between DINdef,OMP and N2bio to estimate a 29% contribution of anammox to N2bio. Stable isotopic measurements of NO2-, NO3-, and N2 were used alongside N2bio and new estimates of DINdef to calculate N and O isotope effects for NO3- reduction (15εNAR and 18εNAR, respectively), and N isotope effects for DIN removal (15εDIN-R). While the various methods for estimating DINdef had little effect on the isotope effects for DIN removal, differences between 15εNAR and 15εDIN-R, and variations with depth in the ODZ were observed. Using a simple time-dependent ODZ model, we interpreted these patterns to reflect the influences of NO2- oxidation and NO2- accumulation on expression of isotopic fractionation in the ODZ.
This study presents a synthesis of surface water partial pressure of CO2 (pCO2) and nutrient observations in the tropical Pacific (20°S–20°N) from 1981 to 2015 and characterizes the spatio-temporal ...variability. We used data from the Surface Ocean CO2 Atlas version 5, which include about 2 million pCO2 measurements in the tropical Pacific. Unlike many previous studies that estimated pCO2 fields from relationships with other variables like sea surface temperature, we developed gridded products of monthly means using a technique to interpolate measured pCO2 values. Large seasonal variation of pCO2 appears in the cold tongue region (EQ–20°S, east of 120°W) corresponding to the seasonal variation of coastal upwelling, and in the off-equatorial region where the thermodynamic effect on pCO2 dominates. Consistent with previous findings, pCO2 along the equator declines during El Niño due to weakening of the easterly winds and therefore reduced upwelling of CO2 rich subsurface water. We also quantified the spatial distribution of the long-term pCO2 trend beyond the area-averaged trend presented previously. The long-term trend of pCO2 is positive in all regions with an area average of 1.8 ± 0.1 μatm yr−1. However, along the equator the trend is > 2 μatm yr−1 linked to the Pacific Decadal Oscillation forcing. Using the same methodology, we also analyzed about 20,000 surface nutrient measurements from the Global Ocean Data Analysis Project version 2, World Ocean Database 2013, and ship-of-opportunity sampling by the National Institute for Environmental Studies, Japan. We present the spatial patterns of reduced surface nutrient concentration in the central to eastern tropics along the equator during El Niño, but there are not enough data to characterize the trends of nutrients in the tropical Pacific.
Decorrelation analyses are also applied using covariance between pCO2 anomalies separated by a lag increment for zonal, meridional, and temporal directions. The e-folding scale of pCO2 is estimated to be 6° in latitude, 13° in longitude, and 2 months with a signal-to-noise ratio of 4, which are used as input for the interpolation as well as an assessment of ideal observation density and frequency. Decorrelation analyses such as this are critical for evaluating existing observing system design and informing future sampling strategies.
Abstract
The structure and variations of the North Equatorial Counter Current (NECC) in the far western Pacific Ocean during 2014-2016 are investigated using repeated in-situ hydrographic data, ...altimeter data, Argo data, and reanalysis data. The NECC shifted ~1 degree southward and intensified significantly with its transport exceeding 40 Sv (1 Sv = 10
6
m
3
s
-1
), nearly double its climatology value, during the developing phase of the 2015/16 El Niño event. Observations show that the 2015/16 El Niño exerted a comparable impact on the NECC with that of the extreme 1997/98 El Niño in the far western Pacific Ocean. Baroclinic instability provided the primary energy source for the eddy kinetic energy (EKE) in the 2015/16 El Niño, which differs from the traditional understanding of the energy source of EKE as barotropic instability in low latitude ocean. The enhanced vertical shear and the reduced density jump between the NECC layer and the subsurface North Equatorial Subsurface Current (NESC) layer renders the NECC–NESC system baroclinically unstable in the western Pacific Ocean during El Niño developing phase. The eddy-mean flow interactions here are diverse associated with various states of the El Niño Southern Oscillation (ENSO).
Using active methods to involve students in teaching improves student learning. For many teachers, breaking up a lecture with multiple choice questions and peer instruction has become an integral ...part of their teaching. We suggest involving students in creating the framework in which they learn together with their teachers. Teaching then becomes mine inclusive, and students try out new roles that support them in becoming more independent, secure, and responsible. Co-creation gives students the chance to feel competent both in class and in their lives, as formative interactions make taught content more relevant to them. Experiencing competency, autonomy, and relatedness is what makes intrinsic motivation possible. It is thus not surprising that co-creation enhances learning and leads to more positive interactions between students and teachers.
Abstract This study examines the impact of changing the lateral diffusion coefficientARedion the transport of the Antarctic Circumpolar Current (ACC). The lateral diffusion coefficientARediis poorly ...constrained, with values ranging across an order of magnitude in climate models. The ACC is difficult to accurately simulate, and there is a large spread in eastward transport in the Southern Ocean (SO) in these models. This paper examines how much of that spread can be attributed to different eddy parameterization coefficients. A coarse-resolution, fully coupled model suite was run withARedi= 400, 800, 1200, and 2400 m2s−1. Additionally, two simulations were run with two-dimensional representations of the mixing coefficient based on satellite altimetry. Relative to the 400 m2s−1case, the 2400 m2s−1case exhibits 1) an 11% decrease in average wind stress from 50° to 65°S, 2) a 20% decrease in zonally averaged eastward transport in the SO, and 3) a 14% weaker transport through the Drake Passage. The decrease in transport is well explained by changes in the thermal current shear, largely due to increases in ocean density occurring on the northern side of the ACC. In intermediate waters these increases are associated with changes in the formation of intermediate waters in the North Pacific. We hypothesize that the deep increases are associated with changes in the wind stress curl allowing Antarctic Bottom Water to escape and flow northward.
ABSTRACT This article shows a comprehensive bibliometric analysis of the literature on polychaetes from Brazil, with a focus on the growth of the field, publication venues, citation patterns, the ...collaboration among the Brazilian community and foreign researchers, and the main research topics over time. The analysis was based on a corpus of 568 articles published in 144 journals, covering a period from 1966 to 2022. The results reveal significant growth in the field, with a surge in publications particularly in the last decade. The top journals for publishing include Zootaxa, JMBA, and Zoologia. However, despite this growth, the overall impact of the research output remains somewhat limited, with most articles receiving relatively low numbers of citations, and those with more citations have broader research questions. This research community directed its efforts especially to taxonomy and phylogenetics research, community ecology, and physiology (ecotoxicology). These topics formed a common ground for more specialized themes. International collaboration was driven by research specialization, better infrastructure, and funding of developed countries. However, seeking collaborations with countries from the global south can also enrich the research conducted by the Brazilian community and stimulate new scientific inquiries. Embracing greater creativity and audacity as well as pursuing common goals, should yet enhance the quality of scientific research and sustain the remarkable growth and consolidation of this renowned research community.
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