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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Evaluation of predictive correlation between flux expulsion and grain growth for superconducting radio frequency cavities

Abstract A series of experiments were carried out in an effort to develop a simple method for predicting the magnetic flux expulsion behavior of high purity niobium used to fabricate superconducting radio frequency (SRF) cavities. Using conventional metallographic characterizations in conjunction with high spatial resolution electron backscattered diffraction-orientation imaging microscopy, we find that the flux expulsion behavior of 1.3 GHz single cell SRF Nb cavities is significantly associated with the grain growth of the Nb material during heat treatment. Most of the Nb grains rapidly grew during 900 °C heat treatment, and were likely full-recrystallized with 1000 °C HT. When compared to the magnetic flux expulsion ratio ( B sc / B nc ) at Δ T = 5 K, the flux expulsion efficiency of the cavities increases with the increase of grain size. Most interestingly, 900 °C HT shows a roughly linear trend that suggests that this criterion could be used to predict the appropriate heat treatment temperature for sufficient flux expulsion behavior in SRF-grade Nb. This result can be used to see if flux expulsion can be predicted by examining the materials coming from Nb vendors, prior to cavity fabrication.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod's high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors

The Alcator C-Mod team has recently developed a feedback system to measure and control surface heat flux in real-time. The system uses real-time measurements of surface heat flux from surface thermocouples and a pulse-width modulated piezo valve to inject low-Z impurities (typically N 2 ) into the private flux region. It has been used in C-Mod to mitigate peak surface heat fluxes >40 MW m -2 down to <10 MW m -2 while maintaining excellent core confinement, H 98 > 1. While the system works quite well under relatively steady conditions, use of it during transients has revealed important limitations on feedback control of impurity seeding in conventional vertical target plate divertors. In some cases, the system is unable to avoid plasma reattachment to the divertor plate or the formation of a confinement-damaging x-point MARFE. This is due to the small operational window for mitigated heat flux in the parameters of incident plasma heat flux, plasma density, and impurity density as well as the relatively slow response of the impurity gas injection system compared to plasma transients. Given the severe consequences for failure of such a system to operate reliably in a reactor, there is substantial risk that the conventional vertical target plate divertor will not provide an adequately controllable system in reactor-class devices. Finally, these considerations motivate the need to develop passively stable, highly compliant divertor configurations and experimental facilities that can test such possible solutions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Magnetic field and flavor effects on the gamma-ray burst neutrino flux

We reanalyze the prompt muon neutrino flux from gamma-ray bursts (GRBs) in terms of the particle physics involved, as in the example of the often-used reference Waxman-Bahcall GRB flux. We first reproduce this reference flux explicitly treating synchrotron energy losses of the secondary pions. Then we include additional neutrino production modes, the neutrinos from muon decays, the magnetic field effects on all secondary species, and flavor mixing with the current parameter uncertainties. We demonstrate that the combination of these effects modifies the shape of the original Waxman-Bahcall GRB flux significantly and changes the normalization by a factor of 3 to 4. As a consequence, the gamma-ray burst search strategy of neutrino telescopes may be based on the wrong flux shape, and the constraints derived for the GRB neutrino flux, such as the baryonic loading, may in fact be much stronger than anticipated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Combined analysis of neutron and photon flux measurements for the Jules Horowitz reactor core mapping

We study the combined analysis of nuclear measurements to improve the knowledge of the irradiation conditions in the experimental locations of the future Jules Horowitz Reactor (JHR). The goal of the present work is to measure more accurately neutron flux, photon flux and nuclear heating in the reactor. In a Material Testing Reactor (MTR), nuclear heating is a crucial parameter to design the experimental devices to be irradiated in harsh nuclear conditions. This parameter drives the temperature of the devices and of the samples. The numerical codes can predict this parameter but in-situ measurements are necessary to reach the expected accuracy. For this reason, one objective of the IN-CORE program [1] is to study the combined measurements of neutron and photon flux and their cross advanced interpretation. It should be reminded that both neutron and photon sensors are not totally selective as their signals are due to neutron and photon interactions. We intend to measure the neutron flux by three different kinds of sensors (Uranium Fission chamber, Plutonium Fission chamber and Self Powered Neutron Detector), the photon flux by two different sensors (Ionization chamber and Self Powered Gamma Detector) and the nuclear heating by two different ones (Differential calorimeter and Gamma Thermometer). For the same parameter, we expect that the use of different kinds of sensors will allow a better estimation of the aimed parameter by mixing different spectrum responses and different neutron and gamma contributions. An experimental test called CARMEN-1 is scheduled in OSIRIS reactor (CEA Saclay - France) at the end of 2011, with the goal to map irradiation locations in the reactor reflector to get a first validation of the analysis model. This article focuses on the sensor selection for CARMEN-1 experiment and to the way to link neutron and photon flux measurements in view to reduce their uncertainties but also to better assess the neutron and photon contributions to nuclear heating. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2020

Design of an Axial Flux Machine With an Integrated Hydraulic Pump for Off-Highway Vehicle Electrification

Axial flux machines offer an inherent torque density advantage over conventional radial flux machines and are increasingly being considered for transportation electrification applications. Electrification of off-highway vehicles is notoriously challenging due to extreme power density requirements. This paper investigates the use of axial flux machines for off-highway vehicle electrification. To maximize the power density, a hydraulic pump is integrated with the axial flux machine, resulting in a single modular, electric/hydraulic machine. This paper first compares three popular axial flux machine variants using an FEA-based design optimization approach. The single rotor, single stator variant is identified to be the most promising for integration with the hydraulic pump. Next, a multi-physics framework of the complete integrated hydraulic pump and axial flux machine is developed to search the design space. The results indicate promising potential for this concept to realize efficiency over 85% and power density over 5kW/kg for the complete machine (electric machine, hydraulic pump, and thermal management system), while utilizing conventional materials (thin gauge silicon steel, N45 magnets, and magnet wire)

Off-highway vehicles, Axial flux machines, Multi-p↗
DOE OSTI2020

Flux Balancing Control of Ungapped Nanocrystalline Core-Based Transformer in Dual Active Bridge Converters

Transformer flux dc bias is a critical issue, impacting the reliable operation of dual active bridge (DAB) converters especially when ungapped high permeability nanocrystalline core is used. Steady state current dc bias can easily saturate ungapped nanocrystalline transformers, and it is even more dangerous in transient conditions. A dc bias model is proposed to analyze steady state dc bias in different load conditions. The magnetizing current detection is necessary for closed-loop control of dc bias; conductors' position is shown to impact sensor noise, and it is analyzed in detail. To deal with both steady state and transient dc bias, a unified flux balancing control (UFBC) is proposed introducing a predictive bias suppression (PBS) method with closed-loop flux balancing control (CFBC). With the proposed PBS, both primary/secondary current balance and flux balance can be achieved within one switching cycle using UFBC. Power characteristics and interaction between power control and flux balancing control of DAB converters are analyzed, and the CFBC needs to work in a low bandwidth due to sensor bandwidth limitation and interaction between power control and flux balancing control. Lastly, the UFBC is verified on a 300-kW cascaded DAB converter prototype.

42 ENGINEERING↗
DOE OSTI2021

Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade

The National Spherical Tokamak Experiment (NSTX) upgrade (NSTX-U) requirements lead to enhanced heat loads on plasma-facing components (PFCs) especially in the divertor regions, where normal heat flux density can reach up to 8 MW/m 2 . For these high heat flux (HHF) regions, the PFCs were redesigned, to use castellations which relieved the thermal stresses associated with high incident heat flux. Another design feature of HHF PFCs is the absence of front face mounting holes which create localized areas of high temperature and thermal stress concentrations. Optimized shaping of the front face of the HHF PFCs eliminates regions where the front face is perpendicular to the heat flux direction during normal helicity operation and spreads the heat load. A unique mechanism was designed to connect PFC tiles to the NSTX-U center stack casing using locking features accessible from the low heat flux regions. Isotropic graphite was selected as the HHF PFC tile material. Initial tile design parameters were accessed using analytical expressions for pulsed heat flux loading. A working prototype of the locking mechanism was created during the initial stages of the design to prove the concept performance. This article presents an overview of the divertor HHF PFC design and the results of the thermal and structural analyses performed using ANSYS software. The results of the analyses cover normal operating conditions and disruptions which impose electromagnetic (EM) loads from eddy and halo currents. The 3-D, transient, nonlinear analyses took into account the temperature-dependent properties of the materials, friction interfaces between the parts, and variable electric properties of the parts and interfaces. The results confirm that the HHF PFC tiles remain within the allowable limits for the loads defined by the NSTX-U Recovery Project. In addition, tolerance stack up analyses were performed to ensure tile performance in the worst possible assembly configuration. Finally, the design process was completed successfully, and the NSTX HHF PFC tiles are currently in the production phase.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks

The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO 2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO 2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO 2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co-acting factors that modulate GPP and RECO flux dynamics. To overcome this limitation, we developed a hybrid data-driven approach based on combined neural networks (NN C-part ). NN C-part incorporates process knowledge by introducing a photosynthetic response based on the light-use efficiency (LUE) concept, and uses a comprehensive dataset of soil and micrometeorological variables as fluxes drivers. We applied the method to 36 sites from the FLUXNET2015 dataset and found a high consistency in the results with those derived from other standard partitioning methods for both GPP (R 2 > .94) and RECO (R 2 > .8). High consistency was also found for (a) the diurnal and seasonal patterns of fluxes and (b) the ecosystem functional responses. NNC-part performed more realistic than the traditional methods for predicting additional patterns of gross CO 2 fluxes, such as: (a) the GPP response to VPD, (b) direct effects of air temperature on GPP dynamics, (c) hysteresis in the diel cycle of gross CO 2 fluxes, (d) the sensitivity of LUE to the diffuse to direct radiation ratio, and (e) the post rain respiration pulse after a long dry period. In conclusion, NN C-part is a valid data-driven approach to provide GPP and RECO estimates and complementary to the existing partitioning methods.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Metabolic network reconstruction and flux variability analysis of storage synthesis in developing oilseed rape (Brassica napus L.) embryos

Computational simulation of large-scale biochemical networks can be used to analyze and predict the metabolic behavior of an organism, such as a developing seed. Based on the biochemical literature, pathways databases and decision rules defining reaction directionality we reconstructed bna572, a stoichiometric metabolic network model representing Brassica napus seed storage metabolism. In the highly compartmentalized network about 25% of the 572 reactions are transport reactions interconnecting nine subcellular compartments and the environment. According to known physiological capabilities of developing B. napus embryos, four nutritional conditions were defined to simulate heterotrophy or photoheterotrophy, each in combination with the availability of inorganic nitrogen (ammonia, nitrate) or amino acids as nitrogen sources. Based on mathematical linear optimization the optimal solution space was comprehensively explored by flux variability analysis, thereby identifying for each reaction the range of flux values allowable under optimality. The range and variability of flux values was then categorized into flux variability types. Across the four nutritional conditions, approximately 13% of the reactions have variable flux values and 10-11% are substitutable (can be inactive), both indicating metabolic redundancy given, for example, by isoenzymes, subcellular compartmentalization or the presence of alternative pathways. About one-third of the reactions are never used and are associated with pathways that are suboptimal for storage synthesis. Fifty-seven reactions change flux variability type among the different nutritional conditions, indicating their function in metabolic adjustments. This predictive modeling framework allows analysis and quantitative exploration of storage metabolism of a developing B. napus oilseed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Observations of Coastal Wind Momentum Flux: Dependence on Fetch and Waves with Comparisons to COARE

Here, using observations from the Martha’s Vineyard Coastal Observatory, this paper investigates how momentum flux in the marine atmospheric surface layer over the coastal ocean varies with fetch, wave age, and wave slope and assesses the performance of the COARE 3.5 bulk parameterization. Long-fetch (at least 300 km) and short-fetch (3–6 km away from land) conditions have very similar momentum flux, with the latter being just 15% higher. The COARE 3.5 wind speed–dependent formulation closely matches the observations. The sea state dependence of wave age and wave slope is analyzed by considering both peak frequency and mean frequency in a wave spectrum. The slope of regression lines between normalized roughness and wave age is sensitive to wind speed ranges and the scatter of momentum flux, potentially explaining why earlier studies did not find a universal formula to characterize the wave dependence. Although the observed momentum flux exhibits an obvious dependence on wave age, a robust quadratic fit between momentum flux and the 10-m neutral wind speed exists only for young waves. For the short-fetch conditions, the momentum flux does not increase as wave slope increases. This may be because waves generated by local wind are still weak and swell that propagates from other areas dominates the wave spectra. In other words, the wave slope computed by considering the spectra does not properly reflect the local wind–wave interaction.

Air-sea interaction↗
DOE OSTI2016

Temperature and neutron flux dependence of in-reactor creep for cold-worked Zr-2.5Nb - 2016-0042

Over the past 10 years, internally pressurized capsules made from Zr-2.5Nb tubing have been irradiated in the National Research Universal (NRU) reactor at Chalk River Laboratories at temperatures of 280, 320, and 340 deg. C and dose rates between 3 X10{sup 15} n. m{sup -2}. s{sup -1} and 2 X10{sup 17} n. m{sup -2}. s{sup -1} (E>1 MeV). Periodic gaging has been used to assess the primary and secondary (steady-state) creep behavior. The objective of this detailed and controlled experiment was to determine, for the first time, the creep and microstructure evolution in Zr-2.5Nb tubing over a wide range of irradiation conditions for fast neutron fluxes applicable to a CANDU pressure tube. Similar but 'accelerated' creep experiments have been conducted in the Osiris test reactor at fast neutron fluxes of approximately 1.8 X10{sup 18} n. m{sup -2}. s{sup -1} (E>1 MeV), much greater than the neutron fluxes in the NRU reactor. Although accelerated tests in high-flux reactors such as Osiris provide information on irradiation creep, they do not represent the neutron flux conditions applicable to a power reactor. Tests covering power reactor operating conditions are needed to develop models for in-reactor creep of pressure tubes under the appropriate conditions. The data from the NRU reactor are compared with results from creep capsules with similar starting microstructures but irradiated in the Osiris reactor. The results show that the steady-state diametral and axial creep rates have a complex dependence on stress, temperature, and fast neutron flux. Data from out-reactor creep tests on unirradiated and pre-irradiated creep capsules that show the effect of prior irradiation on creep are also reported. The results are discussed in terms of a combination of creep mechanisms involving dislocation glide and mass transport. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2016

GAMSOR: Gamma Source Preparation and DIF3D Flux Solution

Nuclear reactors that rely upon the fission reaction have two modes of thermal energy deposition in the reactor system: neutron absorption and gamma absorption. The gamma rays are typically generated by neutron absorption reactions or during the fission process which means the primary driver of energy production is of course the neutron interaction. In conventional reactor physics methods, the gamma heating component is ignored such that the gamma absorption is forced to occur at the gamma emission site. For experimental reactor systems like EBR-II and FFTF, the placement of structural pins and assemblies internal to the core leads to problems with power heating predictions because there is no fission power source internal to the assembly to dictate a spatial distribution of the power. As part of the EBR-II support work in the 1980s, the GAMSOR code was developed to assist analysts in calculating the gamma heating. The GAMSOR code is a modified version of DIF3D and actually functions within a sequence of DIF3D calculations. The gamma flux in a conventional fission reactor system does not perturb the neutron flux and thus the gamma flux calculation can be cast as a fixed source problem given a solution to the steady state neutron flux equation. This leads to a sequence of DIF3D calculations, called the GAMSOR sequence, which involves solving the neutron flux, then the gamma flux, then combining the results to do a summary edit. In this manuscript, we go over the GAMSOR code and detail how it is put together and functions. We also discuss how to setup the GAMSOR sequence and input for each DIF3D calculation in the GAMSOR sequence. With the GAMSOR capability, users can take any valid steady state DIF3D calculation and compute the power distribution due to neutron and gamma heating. The MC2-3 code is the preferable companion code to use for generating neutron and gamma cross section data, but the GAMSOR code can accept cross section data from other sources. To further this aspect, an additional utility code was created which demonstrates how to merge the neutron and gamma cross section data together to carry out a simultaneous solve of the two systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2022

Estimation of Corn Latent Heat Flux from High Resolution Thermal Imagery

Crop evapotranspiration (ET), which is directly related to latent heat flux, is also a key indicator in determining the water status of crops. In order to estimate the latent heat flux, two-source energy balance (TSEB) models have been developed for thermal imagery from satellite platforms. However, because of the coarse resolution of thermal sensors on the satellite, distinguishing soil and vegetation is difficult which complicates the calculation process and introduces errors in latent heat estimates. In this research, high-resolution thermal datasets (0.05 m) and corresponding RGB datasets (0.03 m) were used for calculating crop latent heat flux using an adapted TSEB model. The RGB datasets were used for supervised classification of soil and vegetation, and the classification results were then used to filter the thermal mosaics to separate vegetation and soil temperatures. The vegetation temperature is used for calculating latent heat flux and the results are validated against the ground reference measurements of latent heat using a handheld porometer. The objective of this research is to introduce a workflow including an adapted TSEB model which is customized for high resolution thermal images from unmanned aircraft systems (UAS) to estimate the latent heat flux of row crops in agricultural fields. Nine dates of data collection in 2018 and 2020 have been evaluated and the root mean square error (RMSE) varies between 16 to 106 W/m2 depending on the days after planting (DAP) and the time of measurement for each day. The results indicate that the workflow introduced here is able to provide estimates of instantaneous latent heat flux (evapotranspiration) measurements for row crops in agricultural fields which will enable people to make reliable decisions related to irrigation scheduling.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

THE SOLAR INTERNETWORK. II. FLUX APPEARANCE AND DISAPPEARANCE RATES

Small-scale internetwork magnetic fields are important ingredients of the quiet Sun. In this paper we analyze how they appear and disappear on the solar surface. Using high resolution Hinode magnetograms, we follow the evolution of individual magnetic elements in the interior of two supergranular cells at the disk center. From up to 38 hr of continuous measurements, we show that magnetic flux appears in internetwork regions at a rate of 120 ± 3 Mx cm{sup −2} day{sup −1} (3.7 ± 0.4 × 10{sup 24} Mx day{sup −1} over the entire solar surface). Flux disappears from the internetwork at a rate of 125 ± 6 Mx cm{sup −2} day{sup −1} (3.9 ± 0.5 × 10{sup 24} Mx day{sup −1}) through fading of magnetic elements, cancelation between opposite-polarity features, and interactions with network patches, which converts internetwork elements into network features. Most of the flux is lost through fading and interactions with the network, at nearly the same rate of about 50 Mx cm{sup −2} day{sup −1}. Our results demonstrate that the sources and sinks of internetwork magnetic flux are well balanced. Using the instantaneous flux appearance and disappearance rates, we successfully reproduce the time evolution of the total unsigned flux in the two supergranular cells.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A PROPOSED PARADIGM FOR SOLAR CYCLE DYNAMICS MEDIATED VIA TURBULENT PUMPING OF MAGNETIC FLUX IN BABCOCK–LEIGHTON-TYPE SOLAR DYNAMOS

At present, the Babcock–Leighton flux transport solar dynamo models appear to be the most promising models for explaining diverse observational aspects of the sunspot cycle. The success of these flux transport dynamo models is largely dependent upon a single-cell meridional circulation with a deep equatorward component at the base of the Sun’s convection zone. However, recent observations suggest that the meridional flow may in fact be very shallow (confined to the top 10% of the Sun) and more complex than previously thought. Taken together, these observations raise serious concerns on the validity of the flux transport paradigm. By accounting for the turbulent pumping of magnetic flux, as evidenced in magnetohydrodynamic simulations of solar convection, we demonstrate that flux transport dynamo models can generate solar-like magnetic cycles even if the meridional flow is shallow. Solar-like periodic reversals are recovered even when meridional circulation is altogether absent. However, in this case, the solar surface magnetic field dynamics does not extend all the way to the polar regions. Very importantly, our results demonstrate that the Parker–Yoshimura sign rule for dynamo wave propagation can be circumvented in Babcock–Leighton dynamo models by the latitudinal component of turbulent pumping, which can generate equatorward propagating sunspot belts in the absence of a deep, equatorward meridional flow. We also show that variations in turbulent pumping coefficients can modulate the solar cycle amplitude and periodicity. Our results suggest the viability of an alternate magnetic flux transport paradigm—mediated via turbulent pumping—for sustaining solar-stellar dynamo action.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

The Eruption of a Small-scale Emerging Flux Rope as the Driver of an M-class Flare and of a Coronal Mass Ejection

Solar flares and coronal mass ejections are the most powerful explosions in the Sun. They are major sources of potentially destructive space weather conditions. However, the possible causes of their initiation remain controversial. Using high-resolution data observed by the New Solar Telescope of Big Bear Solar Observatory, supplemented by Solar Dynamics Observatory observations, we present unusual observations of a small-scale emerging flux rope near a large sunspot, whose eruption produced an M-class flare and a coronal mass ejection. The presence of the small-scale flux rope was indicated by static nonlinear force-free field extrapolation as well as data-driven magnetohydrodynamics modeling of the dynamic evolution of the coronal three-dimensional magnetic field. During the emergence of the flux rope, rotation of satellite sunspots at the footpoints of the flux rope was observed. Meanwhile, the Lorentz force, magnetic energy, vertical current, and transverse fields were increasing during this phase. The free energy from the magnetic flux emergence and twisting magnetic fields is sufficient to power the M-class flare. These observations present, for the first time, the complete process, from the emergence of the small-scale flux rope, to the production of solar eruptions.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1964

Orbiter heat flux computer program

A two-phased contract is currently underway to develop 1) a set of parametric curves of absorbed heat flux for specific geometries, and 2) a generalized computer program whose output is absorbed heat flux on the surfaces of a planet orbiting spacecraft. The absorbed heat fluxes include the effects of blockage by and reflections from adjacent spacecraft surfaces, assuming all surfaces to be diffuse. The final computer program will calculate fluxes on any of ten arbitrarily positioned plane surfaces, with any surface properties, planetary radiation characteristics, solar intensity, and orbital parameters. Outputs will be heat fluxes versus time, geometrical configuration factors, and radiant flux interchange factors.

COMPUTER PROGRAM↗
NASA NTRS2015

The Impact of Trends in the Large Scale Atmospheric Circulation on Mediterranean Surface Turbulent Heat Fluxes

Interannual variations of latent heat fluxes (LHF) and sensible heat fluxes (SHF) over the Mediterranean for the boreal winter season (DJF) show positive trends during 1958-2011. Using reanalysis and satellite-based products, the variability and trends in the heat fluxes are compared with variations in three atmospheric teleconnection patterns: the North Atlantic Oscillation (NAO), the pressure and position of the Azores High (AH), and the East Atlantic-West Russia teleconnection pattern (EAWR). Comparison of correlations between the heat fluxes and teleconnections, along with analysis of composites of surface temperature, humidity, and wind fields for different teleconnection states, demonstrates that the AH explains the heat flux changes more successfully than NAO and EAWR. Trends in pressure and longitude of the Azores High show a strengthening and an eastward shift. Variations of the Azores High occur along an axis defined by lower pressure and westward location at one extreme and higher pressure and eastward location at the other extreme. The shift of the AH from predominance of the low/west state to the high/east state induces trends in Mediterranean Sea surface winds, temperature, and moisture. These, combined with sea surface warming trends, produce trends in wintertime sensible and latent heat fluxes.

Latent heat↗