ARM: Carbon Dioxide Flux Wind Data: 60m samples
Carbon Dioxide Flux Wind Data: 60m samples
54 ENVIRONMENTAL SCIENCES↗
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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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Microwave Radiometer: Meteorological Temperature Profiler (raw)
The microwave radiometer profiler (MWRP) provides vertical profiles of temperature, humidity, and cloud liquid water content as a function of height or pressure at approximately 5-minute intervals for nearly all weather conditions. The profiles are derived from measurements of absolute microwave radiances (expressed as "brightness temperatures") obtained at 12 frequencies in the range of 22-30 GHz and 51-59 GHz. The data are useful for input to numerical weather forecast models and others that require continuous, high-temporal-resolution profiles. The microwave radiance measurements are useful for testing models of microwave radiation transfer used to derive the profiles.
54 ENVIRONMENTAL SCIENCES↗
co2flxwind60m (a1)
The Southern Great Plains (SGP) carbon dioxide flux (CO2FLUX) measurement systems provide half-hour average fluxes of CO2, H2O (latent heat), sensible heat, and momentum. The systems use the eddy covariance technique, which computes the fluxes from the vertical wind speed in combination with the concentrations of CO2 and H2O, temperature, and horizontal wind speed, respectively. A 3D sonic anemometer obtains the wind components and the temperature, while an infrared gas analyzer measures CO2 and H2O. A sub-system also measures half-hour averages of radiation, meteorological, and soil measurements.
54 ENVIRONMENTAL SCIENCES↗
CO2 Profiling System for CO2 Storage (a1-level)
The Southern Great Plains (SGP) carbon dioxide flux (CO2FLUX) measurement systems provide half-hour average fluxes of CO2, H2O (latent heat), sensible heat, and momentum. The systems use the eddy covariance technique, which computes the fluxes from the vertical wind speed in combination with the concentrations of CO2 and H2O, temperature, and horizontal wind speed, respectively. A 3D sonic anemometer obtains the wind components and the temperature, while an infrared gas analyzer measures CO2 and H2O. A sub-system also measures half-hour averages of radiation, meteorological, and soil measurements.
54 ENVIRONMENTAL SCIENCES↗
Fast Response Temperature by airborne measurements over BNF
The original data were collected during the AAF Engineering Flights (AEF2025) in the vicinity of the ARM Bankhead National Forest (BNF) Atmospheric Observatory (https://www.arm.gov/capabilities/observatories/bnf ) in northwestern Alabama in March 2025. The ARM Aerial Facility ArcticShark uncrewed aerial system (UAS, https://www.arm.gov/capabilities/observatories/aaf/uas) was based at the public-use airport of Posey Field, Alabama (FAA LID: 1M4, 34.28027778° N, 87.60055556° W, 283m MSL) from March 9 through March 24, 2025. The ArcticShark UAS performed nine flights, including eight research flights over the AMF3 (BNF Main Site) and Supplemental Facilities to measure atmospheric state, turbulence, surface IR temperature and imagery, and aerosol number concentration and size distribution. The current data set presents fast response temperature in the atmospheric boundary layer and lower free troposphere measured on the airborne platform throughout the field campaign. The primary instruments used to create the current data set were the fine wire thermocouple probe, the Aircraft Integrated Meteorological Measurement System (AIMMS-30), the Pitot-static system (part of UAS flight control), and the infrared gas analyzer sensor for H2O and CO2 (LI-840). All parameters used in temperature calculations (static pressure, True Air Speed, and absolute humidity in form of dew point temperature) were included in the data set. For user convenience, one additional parameter was also included: the type of flight flag (level, up, down, turn, and combination of thereof).
Air temperature, fast response↗
A Study of the Kinematic and Dynamic Processes associated with Mesoscale Snowbands in a Midwest United States Snowstorm on 5 February 2020
Mesoscale snowbands are frequently responsible for dumping large amounts of snow over a relatively small region and pose a considerable forecasting challenge. The present study focuses on the mesoscale snowbands observed on 5 February 2020 over the Midwest United States. In order to improve the forecasting of mesoscale snowbands, it is important to understand the processes that organize these features. To this end, we are investigating the kinematic and dynamic processes that shape the mesoscale snowbands using a combination of high-altitude airborne radar, in-situ aircraft measurements, surface observations, and model simulations. This presentation will primarily focus on the three-dimensional structure of the mesoscale snowbands in terms of EXRAD reflectivity and horizontal winds. The horizontal winds are retrieved from the EXRAD scanning-beam Doppler velocities using a VAD technique. These winds, in combination with virtual potential temperature taken from the HRRR operational analysis, are used to compute the bulk Richardson number in order to investigate any contributions to banding features that might be tied to Kelvin-Helmholtz instability. Our analysis does not support the presence of Kelvin-Helmholtz instability. That said, low, but not subcritical, Richardson numbers were found near the top of some banding features in this event and it is possible that the model analysis is smoothing out the virtual potential temperature fields. Finally, we present arguments for using a flight module designed to sample the along-band structures with particular emphasis on observing generating cells and low-level microphysics.
Charles N. Helms↗
Two-dimensional electron gas in monolayer InN quantum wells
We report in this letter experimental results that confirm the two-dimensional nature of the electron systems in a superlattice structure of 40 InN quantum wells consisting of one monolayer of InN embedded between 10 nm GaN barriers. The electron density and mobility of the two-dimensional electron system (2DES) in these InN quantum wells are 5 × 10{sup 15 }cm{sup −2} (or 1.25 × 10{sup 14 }cm{sup −2} per InN quantum well, assuming all the quantum wells are connected by diffused indium contacts) and 420 cm{sup 2}/Vs, respectively. Moreover, the diagonal resistance of the 2DES shows virtually no temperature dependence in a wide temperature range, indicating the topological nature of the 2DES.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Cloud-resolving model intercomparison of an MC3E squall line case: Part I-Convective updrafts: CRM Intercomparison of a Squall Line
A constrained model intercomparison study of a mid-latitude mesoscale squall line is performed using the Weather Research & Forecasting (WRF) model at 1-km horizontal grid spacing with eight cloud microphysics schemes, to understand specific processes that lead to the large spread of simulated cloud and precipitation at cloud-resolving scales, with a focus of this paper on convective cores. Various observational data are employed to evaluate the baseline simulations. All simulations tend to produce a wider convective area than observed, but a much narrower stratiform area, with most bulk schemes overpredicting radar reflectivity. The magnitudes of the virtual potential temperature drop, pressure rise, and the peak wind speed associated with the passage of the gust front are significantly smaller compared with the observations, suggesting simulated cool pools are weaker. Simulations also overestimate the vertical velocity and Ze in convective cores as compared with observational retrievals. The modeled updraft velocity and precipitation have a significant spread across the eight schemes even in this strongly dynamically-driven system. The spread of updraft velocity is attributed to the combined effects of the low-level perturbation pressure gradient determined by cold pool intensity and buoyancy that is not necessarily well correlated to differences in latent heating among the simulations. Variability of updraft velocity between schemes is also related to differences in ice-related parameterizations, whereas precipitation variability increases in no-ice simulations because of scheme differences in collision-coalescence parameterizations.
Fan, Jiwen↗
Quantum dot lasers with asymmetric barrier layers: Close-to-ideal threshold and power characteristics
A theory of static (threshold and power) characteristics of novel diode lasers – quantum dot (QD) lasers with asymmetric barrier layers (ABLs) – is developed. The barrier layers are asymmetric in that they have considerably different heights for the carriers of opposite signs. The ABL located on the electron- (hole-) injecting side of the structure provides a low barrier (ideally no barrier) for electrons (holes) [so that it does not prevent electrons (holes) from easily approaching the active region] and a high barrier for holes (electrons) [so that holes (electrons) injected from the opposite side of the structure do not overcome it]. The use of ABLs should thus ideally prevent the simultaneous presence of electrons and holes (and hence parasitic electron – hole recombination) outside the QDs. It is shown in this work that in such a case of total suppression of parasitic recombination, the QD lasers with ABLs offer close-to-ideal performance: the threshold current density is below 10 A cm{sup −2} at any temperature, the absolute value of the characteristic temperature is above 1000 K (which manifests a virtually temperature-independent operation), the internal differential quantum efficiency is practically unity, and the light – current characteristic is linear at any pump current. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Virtual Engineering of Low-Temperature Conversion
In this work, we present the development of an overarching software framework and supporting multiphysics models to simulate the end-to-end process of biomass conversion. This virtual engineering (VE) software is designed with the goal of accelerating research and development and reducing risk for market-relevant biomass conversion processes. We currently support multiple models, computing paradigms, and fidelities representing the steps of feedstock pretreatment, enzymatic hydrolysis, and bioconversion. Although this VE approach was developed to support a biomass workflow, we have designed each component in a way that allows us to easily support new domains, unit models, and feedstocks. We begin by presenting the user-facing aspects of the VE software and highlight how simulated elements are defined and linked by VE functions. We then present an overview of the high-fidelity computational fluid dynamics (CFD) models developed to support our target domain before segueing into our efforts to develop accurate and fast surrogate models, capturing the salient outcomes from the CFD simulations in a significantly less computationally demanding manner. We then present how VE calculations interface with a commercial techno-economic analysis software, Aspen Plus. We conclude by presenting VE case studies that leverage these methods and discuss how our methods can be extended to support a wide variety of accelerated biofuel commercialization pathways in the future.
biofuel↗
Thermodynamic budget diagrams for the hurricane subcloud layer
The idealized hurricane boundary layer budget from Malkus and Riehl (1960) are reexamined using vector diagrams for the thermodynamic budgets in the light of recent observational studies. A large air-sea temperature difference can only be maintained with both large fluxes through cloud-base level and a large evaporative cooling of the subcloud layer. The high equivalent potential temperature values observed in hurricane eyewalls can be reached if these cloud-base and evaporative fluxes are reduced and the subcloud layer moves toward the sea surface virtual potential temperature.
Betts, Alan K.↗
Thermal state of an ice shell on Europa
The thickness of the ice shell presently hypothesized for Europa, which is decoupled from a silicate core by a liquid water layer, is calculated as a function of colatitude and longitude under suitable assumptions for two plausible ice rheology behaviors: that of Maxwell type, and that of generalized flow-law rheology. Due to the dissipation rate's pronounced temperature dependence, virtually all tidal dissipation is found to concentrate in the lowest few kilometers of the shell. While for some parameter choices an insulating regolith that raises the near-surface temperature by more than a few tens of degrees C may stabilize the shell against polar wander, a modest regolith may enhance the probability of such wander's occurrence through the reduction of the shell's retarding friction.
Ojakangas, Gregory W.↗
Influence of Cs Promoter on Ethanol Steam-Reforming Selectivity of Pt/m-ZrO 2 Catalysts at Low Temperature
The decarboxylation pathway in ethanol steam reforming ultimately favors higher selectivity to hydrogen over the decarbonylation mechanism. The addition of an optimized amount of Cs to Pt/m-ZrO 2 catalysts increases the basicity and promotes the decarboxylation route, converting ethanol to mainly H 2 , CO 2 , and CH 4 at low temperature with virtually no decarbonylation being detected. This offers the potential to feed the product stream into a conventional methane steam reformer for the production of hydrogen with higher selectivity. DRIFTS and the temperature-programmed reaction of ethanol steam reforming, as well as fixed bed catalyst testing, revealed that the addition of just 2.9% Cs was able to stave off decarbonylation almost completely by attenuating the metallic function. This occurs with a decrease in ethanol conversion of just 16% relative to the undoped catalyst. In comparison with our previous work with Na, this amount is—on an equivalent atomic basis—just 28% of the amount of Na that is required to achieve the same effect. Thus, Cs is a much more efficient promoter than Na in facilitating decarboxylation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Fe XXV temperatures in flares from the Yohkoh Bragg crystal spectrometer
Studies by Doschek et al. using P78-1 and Solar Maximum Misson (SMM) data have shown that the ratio of intensities of the Fe XXV and Ca XIX resonance lines can be expressed as a function of Fe XXV temperature. Using a more recent data set consisting of 13 flares observed by the Bragg crystal spectrometer (BCS) experiment on board Yohkoh, we find a nearly identical functional relationship between the same resonance line ratios and Fe XXV temperatures. We use this functional relationship to obtain resonance line ratio temperatures (T(sub RLR)) for each flare in our data set, and compare them with temperatures resulting from application of a simple spectral fitting method. (T(sub SSF)) to individal Fe XXV spectra. We also use a more involved free-parameter spectral fitting method to deduce temperatures (T(sub FSF)) from some of these spectra. On average, agreement between T(sub RLR) and T(sub SSF) improves as a flare progresses in time, with average agreements of 10.0% +/- 5.2%, 6.4% +/- 5.4%, and 5.0% +/- 3.9% over the rise, peak, and decay phases, respectively. Deviations between T(sub RLR) and T(sub FSF) are about the same or smaller. Thus, for most analysis purposes, all three methods yield virtually identical temperatures in flares. The somewhat poorer agreement between T(sub SSF) and T(sub RLR) during the earlier phases may be partially a result of difficulties in obtaining precise values for temperatures from spectral fits when blueshifts and large nonthermal broadenings are present in the spectra. Because of the high sensitivity of the Yohkoh BCS compared to that of BCS experiments on earlier spacecraft, we can for the first time consistently observe the heating phase of flares in Fe XXV.
Sterling, Alphonse C.↗
Understanding Mesoscale Aggregation of Shallow Cumulus Convection Using Large-Eddy Simulation
Marine shallow cumulus convection, often mixed with thin stratocumulus, is commonly aggregated into mesoscale patches. The mechanism and conditions supporting this aggregation are elucidated using 36 h large-eddy simulations (LES) on a 128 3 128 km doubly periodic domain, using climatological summertime forcings for a location southeast of Hawaii. Within 12 h, mesoscale patches of higher humidity, more vigorous cumulus convection, and thin detrained cloud at the trade inversion base develop spontaneously. Mesoscale 16 3 16 km subdomains are composited into quartiles of column total water path and their heat and moisture budgets analyzed. The weak temperature gradient approximation is used to explain how apparent heating perturbations drive simulated mesoscale circulations, which in turn induce relative moistening of the moistest subdomains, a form of gross moist instability. Self-aggregation is affected by precipitation and mesoscale feedbacks of radiative and surface fluxes but still occurs without them. In that minimal-physics setting, the humidity budget analysis suggests self-aggregation is more likely if horizontal-mean humidity is a concave function of the horizontal-mean virtual potential temperature, a condition favored by radiative cooling and cold advection within the boundary layer.
54 ENVIRONMENTAL SCIENCES↗
Sonic Detection and Ranging (SODAR) Wind Profiler Instrument Handbook
The SODAR (Sonic Detection and Ranging) wind profiler measures wind profiles and backscattered signal strength between (nominally) 15 meters (m) and 500 m. It operates by transmitting acoustic energy into the atmosphere and measuring the strength and frequency of backscattered energy. The strength of the backscattered signal is determined by the strength of temperature inhomogeneities with size on the order of 10 centimeters (cm). Assuming the scattering elements in the atmosphere are moving with the mean wind, the horizontal wind field can be derived. The U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Mobile Facility (AMF) has a system developed by Scintec, Inc. that transmits a sequence of frequencies to enhance signal determination.
17 WIND ENERGY↗
Heat pipe heat rejection system
A prototype of a battery heat rejection system was developed which uses heat pipes for more efficient heat removal and for temperature control of the cells. The package consists of five thermal mock-ups of 100 amp-hr prismatic cells. Highly conductive spacers fabricated from honeycomb panels into which heat pipes are embedded transport the heat generated by the cells to the edge of the battery. From there it can be either rejected directly to a cold plate or the heat flow can be controlled by means of two variable conductance heat pipes. The thermal resistance between the interior of the cells and the directly attached cold plate was measured to be 0.08 F/Watt for the 5-cell battery. Compared to a conductive aluminum spacer of equal weight the honeycomb/heat pipe spacer has approximately one-fifth of the thermal resistance. In addition, the honeycomb/heat pipe spacer virtually eliminates temperature gradients along the cells.
Kroliczek, E. J.↗
Composited structure of non-precipitating shallow cumulus clouds
The normalized distributions of thermodynamic and dynamical variables both within and outside shallow clouds are investigated through a composite algorithm using large-eddy simulations of oceanic and continental cases. The normalized magnitude is maximum near the cloud centre and decreases outwards. While relative humidity (RH) and cloud liquid water ( q l ) decrease smoothly to match the environment, the vertical velocity, virtual potential temperature (θ v ), and potential temperature (θ) perturbations have more complicated behaviour towards the cloud boundary. Below the inversion layer, θ' v becomes negative before the vertical velocity has turned from an updraft to a subsiding shell outside the cloud, indicating the presence of a transition zone where the updraft is negatively buoyant. Due to the downdraft outside the cloud and enhanced horizontal turbulent mixing across the edge, the normalized turbulent kinetic energy (TKE) and horizontal turbulent kinetic energy (HTKE) decrease more slowly from the cloud centre outwards than the thermodynamic variables. The distributions all present asymmetric structures in response to the vertical wind shear, with more negatively buoyant air, stronger downdrafts, and larger TKE on the downshear side. We discuss several implications of the distributions for theoretical models and parameterizations. Positive buoyancy near the cloud base is mostly due to the virtual effect of water vapour, emphasizing the role of moisture in triggering. The mean vertical velocity is found to be approximately half the maximum vertical velocity within each cloud, providing a constraint to achieve possible power-law distributions for some models. Finally, the normalized distributions for different variables are used to estimate the vertical heat and moisture fluxes within clouds. The results suggest that distributions near the cloud edge and variability of maximum perturbations need careful treatment. The fluxes are underestimated in the inversion layer because cloud-top downdrafts cannot be captured well.
54 ENVIRONMENTAL SCIENCES↗