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Compiled TBS data from Oliktok Point from ICARUS, AVPOP, and POPEYE
The dataset encompasses QA/QC TBS data, including TBS altitude, atmospheric pressure, dew point, POPs number concentrations and mean aerosol size, relative humidity, temperature, equivalent potential temperature, equivalent temperature, and date and time. These data are provided per day for at least one TBS flight. Supporting data from the AMF3 aligned with the timestamps of the TBS data include cloud base distance from TBS, if the time corresponds to cloud base transit of the TBS, surface-based pressure, surface-based precipitation rate, surface-based UHSAS data, ceilometer cloud base height, KAZR cloud top height, and MWR liquid water content. Both POPS and UHSAS aerosol number concentrations are provided as: (1) absolute (i.e. concentrations for each instrument's total size range) and (2) the overlapping size range (i.e. the same size bins for both instruments).
KAZRARSCL-CLOUDSAT Value Added Product Data Stream
The KAZRARSCL-CLOUDSAT Value-Added Product (VAP) is based on the KAZR-ARSCL VAP, which provides cloud boundaries and best-estimate time-height fields of radar moments. The KAZRARSCL-CLOUDSAT VAP applies a statistically-derived calibration offset to reflectivity fields in order to align them with observations from the spaceborne CloudSat Cloud Profiling Radar. For details on the offset values applied, please refer to "Kollias, P., Puigdomènech Treserras, B., and Protat, A.: Calibration of the 2007–2017 record of ARM Cloud Radar Observations using CloudSat, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2019-34, 2019."
KAZR-based snowfall rates during SAIL
This data set provides KAZR radar based retrievals of snowfall rates for the two cold periods of the SAIL campaign (NOV 2021- APR 2022 and NOV 2022 - APR 2023).
Unattended Atmospheric Measurement System (UAMS)
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Multifrequency radar observations of clouds and precipitation including the G-band
Abstract. Observations collected during the 25 February 2020 deployment of the Vapor In-Cloud Profiling Radar at the Stony Brook Radar Observatory clearly demonstrate the potential of G-band radars for cloud and precipitation research, something that until now was only discussed in theory. The field experiment, which coordinated an X-, Ka-, W- and G-band radar, revealed that the Ka–G pairing can generate differential reflectivity signal several decibels larger than the traditional Ka–W pairing underpinning an increased sensitivity to smaller amounts of liquid and ice water mass and sizes. The observations also showed that G-band signals experience non-Rayleigh scattering in regions where Ka- and W-band signal do not, thus demonstrating the potential of G-band radars for sizing sub-millimeter ice crystals and droplets. Observed peculiar radar reflectivity patterns also suggest that G-band radars could be used to gain insight into the melting behavior of small ice crystals. G-band signal interpretation is challenging, because attenuation and non-Rayleigh effects are typically intertwined. An ideal liquid-free period allowed us to use triple-frequency Ka–W–G observations to test existing ice scattering libraries, and the results raise questions on their comprehensiveness. Overall, this work reinforces the importance of deploying radars (1) with sensitivity sufficient enough to detect small Rayleigh scatters at cloud top in order to derive estimates of path-integrated hydrometeor attenuation, a key constraint for microphysical retrievals; (2) with sensitivity sufficient enough to overcome liquid attenuation, to reveal the larger differential signals generated from using the G-band as part of a multifrequency deployment; and (3) capable of monitoring atmospheric gases to reduce related uncertainty.
Measuring the Debye energy in superconductors via two-electron photoemission spectroscopy
In this work, we demonstrate theoretically that double angle resolved photoemission spectroscopy (2eARPES) can directly probe the existence of Cooper pairs away from the Fermi surface, and can thus provide insight into the characteristic energy scale around the Fermi surface, the Debye energy, in which electrons are bound into Cooper pairs. To this end, we compute the photoelectron counting rate 𝑃 (2) in two different types of unconventional superconductors, a 𝑑 𝑥 2 −𝑦 2 -wave superconductor, and a topological superconductor with a broken time-reversal symmetry. We show that 𝑃 (2) provides insight into the relative strength of intra- and interband pairing in multiband systems, as well as into the spin polarization of the bands.
Training the next generation of researchers in exploring cloud dynamics and microphysics using millimeter-wavelength radars
Millimeter-wavelength radars, with their ability to collect observations and high spatiotemporal resolution, have become cornerstone instruments for investigating cloud and precipitation microphysics and dynamics in the last two decades. Since the1990s the US Department of Energy Atmospheric Radiation Measurement (ARM) program has invested in mm-wavelength radar technology progressively adding scanning capability, additional frequencies and polarimetric capability. In addition, atmospheric observatories including those technologies have been operated overseas. Those technologies have enhanced our understanding of cloud and precipitation processes. Only a few universities operate those instruments and use them for educational purposes. The central role of mm- wavelength radars and their role will be further highlighted in the next decade. NASA and other international space agencies are planning to launch millimeter-wavelength (i.e., Ku, Ka, W, G- bands) Doppler radar in space to improve our understanding of cloud and precipitation formation, evolution and their impacts on global climate.
Shot noise and differential conductance as signatures of putative topological superconductivity in FeSe 0.45 Te 0.55
We present a theory for the differential shot noise, dS/dV, as measured via shot-noise scanning tunneling spectroscopy, and the differential conductance, dI/dV, for tunneling into Majorana zero modes (MZMs) in the putative topological superconductor FeSe 0.45 Te 0.55 . We demonstrate that for tunneling into chiral Majorana edge modes near domain walls, as well as MZMs localized in vortex cores and at the end of defect lines, dS/dV vanishes whenever dI/dV reaches a quantized value proportional to the quantum of conductance. Furthermore, these results are independent of the particular orbital tunneling path, thus establishing a vanishing dS/dV concomitant with a quantized dI/dV, as universal signatures for Majorana modes in two-dimensional topological superconductors, irrespective of the material’s specific complex electronic band structure.
Noninteracting electrons in a prototypical one-dimensional sinusoidal potential
A prototypical model of a one-dimensional metallic monatomic solid containing noninteracting electrons is studied, where the argument of the cosine potential energy, periodic with the lattice, contains the first reciprocal lattice vector G 1 =2π/a, where a is the lattice constant. The time-independent Schrödinger equation can be written in reduced variables as a Mathieu equation for which numerically exact solutions for the band structure and wave functions are obtained. The band structure has band gaps that increase with increasing amplitude q of the cosine potential. In the extended-zone scheme, the energy gaps decrease with increasing index n of the Brillouin-zone boundary ka=nπ, where k is the crystal momentum of the electron. The wave functions of the band electron are derived for various combinations of k and q as complex combinations of the real Mathieu functions with even and odd parity, and the normalization factor is discussed. The wave functions at the bottoms and tops of the bands are found to be real or imaginary, respectively, corresponding to standing waves at these energies. Irrespective of the wave vector k within the first Brillouin zone, the electron probability density is found to be periodic with the lattice. The Fourier components of the wave functions are derived versus q, which reveal multiple reciprocal-lattice-vector components with variable amplitudes in the wave functions unless q = 0. The magnitudes of the Fourier components are found to decrease exponentially as a power of n for n~3 to 45 for ka = π/2 and q = 2, and a precise fit is obtained to the data. The probability densities and probability currents obtained from the wave functions are also discussed. The probability currents are found to be zero for crystal momenta at the tops and bottoms of the energy bands, because the wave functions for these crystal momenta are standing waves. To conlcude, the band structure is calculated from the central equation and compared to the numerically exact band structure.
High-resolution rovibrational spectroscopy of trans -formic acid in the v 1 OH stretching fundamental: Dark state coupling and evidence for charge delocalization dynamics
High-resolution infrared (IR) reduced-Doppler absorption spectra of jet-cooled gas phase trans-formic acid in the v 1 OH stretching fundamental region are reported for the first time, obtained by supersonically expanding trans- formic acid/Ar mixtures through a slit jet nozzle source and rotationally cooling to T rot ≈ 10.9(5) K, with ab- sorption signals recorded by high-resolution difference-frequency IR absorption spectroscopy. Two a/b-type rovibrational bands of comparable intensity, one ~10-fold weaker b-type band, and one ~6-fold weaker a-type band are observed, with vibrational band origins at 3570.493(5), 3566.793(5), 3560.032(9), and 3534.6869(2) cm –1 , respectively. Based on previous Raman jet spectroscopic work by Nejad and Sibert [A. Nejad, E.L. Sibert III, The Raman jet spectrum of trans-formic acid and its deuterated isotopologs: Combining theory and experi- ment to extend the vibrational database, J. Chem. Phys. 154(6) (2021) 064301.], these four rovibrational bands have been assigned to v 1 , (v 2 + v 7 ), (v 6 + 2v 7 + 2v 9 ), and 2v 3 , respectively. Specifically, two of the three upper dark states (2 1 7 1 (a') and 6 1 7 2 9 2 (a')) are close enough to the “bright” 1 1 (a') state to facilitate strong anharmonic resonance interactions, which results in intensity mixing into the two zero-order bands that would otherwise be “dark”. Furthermore, our high-resolution spectral analysis reveals that there are local rotational crossings be- tween these zero-order 1 1 and 2 1 7 1 states resulting in extra lines (i.e., some upper levels in the nominally v 1 band have majority zero-order 2 1 7 1 state character). This motivates development of a 3 coupled state (1 1 , 2 1 7 1 , and 6 1 7 2 9 2 ) picture to aid in the spectral analysis, which is able to match all 3 observed band origins and relative band intensities, as well as indicate the necessity of multistate (> 2) coupling. Though limited by range of J and Ka levels (J’ ≤ 9 and K a ’ ≤ 3) populated at supersonic jet temperatures, this work offers first precision spec- troscopic analysis of trans-formic acid in the v 1 OH stretch region, which should aid in assignment of the more complete yet highly congested room temperature FTIR spectra. Lastly, and in sharp contrast to the spectral complexity in the three predominantly b-type bands, the lone a-type 2v 3 rovibrational band at 3534.6869(2) cm –1 is well described by a simple, rigid asymmetric top Hamiltonian.
High-current, high-voltage AlN Schottky barrier diodes
AlN Schottky barrier diodes with low ideality factor (<1.2), low differential ON-resistance (<0.6 mΩ cm 2 ), high current density (>5 kA cm −2 ), and high breakdown voltage (680 V) are reported. The device structure consisted of a two-layer, quasi-vertical design with a lightly doped AlN drift layer and a highly doped Al 0.75 Ga 0.25 N ohmic contact layer grown on AlN substrates. A combination of simulation, current–voltage measurements, and impedance spectroscopy analysis revealed that the AlN/AlGaN interface introduces a parasitic electron barrier due to the conduction band offset between the two materials. This barrier was found to limit the forward current in fabricated diodes. Further, we show that introducing a compositionally-graded layer between the AlN and the AlGaN reduces the interfacial barrier and increases the forward current density of fabricated diodes by a factor of 10 4 .
Optical emission spectroscopy and imaging of low-pressure N2 plasmas generated by intense fast-pulsed electron beams
An optical emission spectroscopic (OES) and imaging characterization is conducted on N2 plasmas generated by a 100 keV fast-pulsed electron beam. The electron beams are injected into an N2 gas filled volume with a current of 4.5 kA (300 A/cm2) and a 100 ns pulse width. The characterization is conducted at the pressures, 1 Torr and 0.1 Torr, corresponding to two distinct regimes that exhibit significantly different plasma dynamics. Beam impact ionization is shown to be a primary mechanism for producing low temperature plasmas at 1 Torr during beam output. After beam termination, ionization by an inductive electric field becomes the primary mechanism for plasma formation later in time for both pressures. OES and plasma imaging are used in this work as a diagnostic tool to track the distribution of electronic, vibrational, and rotational state transitions and ionized species. This is achieved with the use of a multi-resolution suite of spectrometers capable of acquiring time-resolved spectra. Vibrational and rotational bands of the N2 second positive system (C3Πu→B3Πg) and the N2+ first negative system (B2Σu+→X2Σg+) are identified in both regimes as well as N+ states exclusively in the lower pressure regime. Vibrational and rotational spectra are shown to track the evolution of the time-varying plasma current. Plasma imaging also reveals spatially nonuniform plasma emission at 0.1 Torr. A few hundred shots are recorded to fully characterize the emissions, and results are shown to be highly reproducible (≤±1% with 2σ confidence).
Applying the Velocity Gradient Technique in NGC 1333: Comparison with Dust Polarization Observations
Magnetic fields (B-fields) are ubiquitous in the interstellar medium (ISM), and they play an essential role in the formation of molecular clouds and subsequent star formation. However, B-fields in interstellar environments remain challenging to measure, and their properties typically need to be inferred from dust polarization observations over multiple physical scales. In this work, we seek to use a recently proposed approach called the velocity gradient technique (VGT) to study B-fields in star-forming regions and compare the results with dust polarization observations in different wavelengths. The VGT is based on the anisotropic properties of eddies in magnetized turbulence to derive B-field properties in the ISM. We investigate that this technique is synergistic with dust polarimetry when applied to a turbulent diffused medium for the purpose of measuring its magnetization. Specifically, we use the VGT on molecular line data toward the NGC 1333 star-forming region ( 12 CO, 13 CO, C 18 O, and N 2 H + ), and we compare the derived B-field properties with those inferred from 214 and 850 μm dust polarization observations of the region using Stratospheric Observatory for Infrared Astronomy/High-Resolution Airborne Wide-band Camera Plus and James Clerk Maxwell Telescope/POL-2, respectively. We estimate both the inclination angle and the 3D Alfvénic Mach number M A from the molecular line gradients. Crucially, testing this technique on gravitationally bound, dynamic, and turbulent regions, and comparing the results with those obtained from polarization observations at different wavelengths, such as the plane-of-sky field orientation, is an important test on the applicability of the VGT in various density regimes of the ISM. We in general do not find a close correlation between the velocity gradient inferred orientations and the dust inferred magnetic field orientations.