Inversion Layer Research Articles

Seasonal variations of diurnal cycles of aerosols and gases in the Fukuoka Plain, Japan: Effects of local meteorology and atmospheric chemistry

Simultaneous measurements of wind profiles and of atmospheric substances such as aerosols and reactive gases were conducted at Fukuoka University in the western urban area of Japan to elucidate relations between local circulation and variations of aerosols and gases. Spatial variations of wind speed and direction over the Fukuoka Plain were measured using Doppler LIDAR. Some atmospheric substances such as black carbon, organic carbon, CO, and NOx were found to have maxima in morning (07–11 JST) and evening (18–20 JST), when diurnal cycles of wind direction and speed were observed near the surface. Doppler LIDAR data indicated clearly that the diurnal cycles of wind profiles were associated with sea breezes and land breezes over the Fukuoka Plain. The diurnal variations of aerosols and gases might be attributed to local anthropogenic emissions such as vehicle exhaust from Fukuoka city and vessels in the Hakata Bay and the sea and land breeze cycles. Strengths of morning peaks and evening peaks showed clear seasonal changes, with stronger peaks during the colder seasons and weaker peaks during the warmer and hot months. Slopes related to BC, OC, NOx, and CO were found to have seasonal changes. These seasonal changes were associated with the presence of a surface inversion layer in colder seasons, efficient photochemical reactions in the summer, and changes of fuel emission factors.

Novel Backside Structure for Reverse Conducting Insulated-Gate Bipolar Transistor With Two Different Collector Trench

A novel reverse-conducting insulated gate bipolar transistor (RC-IGBT) with two different collector trench (DCT) is proposed. One of the collector trenches is filled with heavily doped N-type polysilicon (N-poly) and the other is filled with heavily doped N- and P-poly. An electron accumulation layer is formed along the sidewall of trench owing to built-in potential difference between the N-poly and the N-drift region. The electron accumulation layer and collector trenches block the electric field, which behaves just like the N-buffer layer of the conventional RC-IGBT (Con. RC-IGBT). Similarly, due to potential difference between the P-poly and N-drift region, a high-density hole inversion layer is formed to narrow the electron current path as a high resistance. The DCT RC-IGBT achieves snapback-free in a small cell pitch without additional control. Moreover, the DCT RC-IGBT shows better tradeoff between turn-off loss and ON-state voltage drop than that of con. RC-IGBT. For the same forward voltage drop, the turn-off loss is reduced by 26%.

K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere

K2-141 b is a transiting, small (1.5 R⊕) ultra-short-period (USP) planet discovered by the Kepler space telescope orbiting a K-dwarf host star every 6.7 h. The planet's high surface temperature of more than 2000 K makes it an excellent target for thermal emission observations. Here we present 65 h of continuous photometric observations of K2-141 b collected with Spitzer's Infrared Array Camera (IRAC) Channel 2 at 4.5 μm spanning ten full orbits of the planet. We measured an infrared eclipse depth of ${f_{{{\rm{p}} \mathord{\left/ {\vphantom {{\rm{p}} {{{\rm{f}}_{\rm{*}}}}}} \right. \kern-\nulldelimiterspace} {{{\rm{f}}_{\rm{*}}}}}}} = 142.9_{ - 39.0}^{38.5}$ ppm and a peak to trough amplitude variation of $A = 120.6_{ - 43.0}^{42.3}$ ppm. The best fit model to the Spitzer data shows no significant thermal hotspot offset, in contrast to the previously observed offset for the well-studied USP planet 55 Cnc e. We also jointly analyzed the new Spitzer observations with the photometry collected by Kepler during two separate K2 campaigns. We modeled the planetary emission with a range of toy models that include a reflective and a thermal contribution. With a two-temperature model, we measured a dayside temperature of ${T_{{\rm{p,d}}}} = 2049_{ - 359}^{362}$ K and a night-side temperature that is consistent with zero (Tp,n < 1712 K at 2σ). Models with a steep dayside temperature gradient provide a better fit to the data than a uniform dayside temperature (ΔBIC = 22.2). We also found evidence for a nonzero geometric albedo ${A_{\rm{g}}} = 0.282_{ - 0.078}^{0.070}$. We also compared the data to a physically motivated, pseudo-2D rock vapor model and a 1D turbulent boundary layer model. Both models fit the data well. Notably, we found that the optical eclipse depth can be explained by thermal emission from a hot inversion layer, rather than reflected light. A thermal inversion may also be responsible for the deep optical eclipse observed for another USP, Kepler-10 b. Finally, we significantly improved the ephemerides for K2-141 b and c, which will facilitate further follow-up observations of this interesting system with state-of-the-art observatories such as James Webb Space Telescope.

Design of Polymer-Based Trigate Nanoscale FinFET for the Implementation of Two-Stage Operational Amplifier

The major motivation behind transistor scaling is the requirement for high-speed transistors with lower fabrication costs. When the fin thickness or breadth is smaller than 10 nm in a trigate FET, charges travel in a nonconfined fashion, resulting in the creation of energy subbands and causing volume inversion. In comparison to the carrier near a surface inversion layer, volume inversion experiences less interface scattering. In large-scale integrations, we have focused on developing a 3D model for surface potential by establishing the three-dimensional Poison’s equation and building a unique fin field-effect transistor (FinFET) structure. In this context, there is a growing interest in developing a low-cost, simple solution that combines plastic (polymer) as a substrate and organic materials to create electronics such as monitors and sensors. The research examines characteristics such as silicon width, oxide thickness, doping concentration, metal work-function about gate, and various surface potentials. For different circuit configurations, it also examines the DC and AC characteristics of the FinFET structure. A differential amplifier is built for RF application based on the device specifications. This work is aimed at improving the semiconductor design structure by adjusting device parameters, analyzing the results, establishing the best FinFET device preferences, and selecting an application for the optimized device. The 3D Poisson’s equation may be used to create an analytical model of a trigate nanosize FinFET, which can then be tested using a TCAD simulator. By constructing such a FinFET, we can structure and analyze various electrostatic parameters. To facilitate the creation of FinFET-based circuits, including product development, a novel transistor needs a creative device basis. The infrastructure’s support denotes a computationally advantageous numerical model that accurately depicts a FinFET. The work presents a compact model for semiconductor manufacturing that permits separate IC productions while achieving higher levels of excellence and using less power. The design outperforms the CMOS by 22.7% in gain, 31.48% in power consumption, and 12.72% in CMRR, while operating at a 5 GHz unity gain frequency.

Characterizing a Heavy Dust Storm Event in 2021: Transport, Optical Properties and Impact, Using Multi-Sensor Data Observed in Jinan, China

On 15 March 2021, the strongest sandstorm of the last 10 years occurred in China. The MODIS, MPL lidar, EDM 180, ADI 2080 and Meteorological observation instruments were used to observe the dust in Jinan, China, while the HYSPLIT model was also employed to find the source. It was found that the dust originated from Mongolia and the Gobi desert and was transported to Jinan at night on 14th March, lasting until the 18th. Multi-layer dust was observed, of which the dust below the height of 1 km was strongest with the VDR about 0.2 and the maximum extinction coefficient up to 3 km−1. The values of AOD and AE were greater than 2 and less than 0.25, respectively. The mass concentrations of PM10 and PM2.5 increased rapidly, and were up to 573 µg/m3 and 3406 µg/m3, respectively. Additionally, the mass concentration ratio decreased rapidly, with a minimum of 17%. The particle size of the dust was mainly distributed between 0.58–6.50 micros due to larger particles increasing dramatically; simultaneously, both the proportion and the value for calcium ions in PM2.5 went up. The dust had an obvious impact on the vertical structure of the air temperature, resulting in occurrence of a strong inversion layer.

Band Flattening and Landau Level Merging in Strongly-Correlated Two-Dimensional Electron Systems

We review recent experimental results indicating the band flattening and Landau level merging at the chemical potential in strongly-correlated two-dimensional (2D) electron systems. In ultra-clean, strongly interacting 2D electron system in SiGe/Si/SiGe quantum wells, the effective electron mass at the Fermi level increases monotonically in the entire range of electron densities, while the energy-averaged mass saturates at low densities. The qualitatively different behavior of the two masses reveals a precursor to the interaction-induced single-particle spectrum flattening at the chemical potential in this electron system, in which case the fermion “condensation” at the Fermi level occurs in a range of momenta, unlike the condensation of bosons. In strong magnetic fields, perpendicular to the 2D electron layer, a similar effect of different fillings of quantum levels at the chemical potential—the merging of the spin- and valley-split Landau levels at the chemical potential—is observed in Si inversion layers and bilayer 2D electron system in GaAs. Indication of merging of the quantum levels of composite fermions with different valley indices is also reported in ultra-clean SiGe/Si/SiGe quantum wells.

Mechanism of the effect of vertically propagating internal gravity waves on turbulence barrier and pollutant diffusion during heavy haze episodes

During heavy haze episodes, especially the cumulative stage (CS) of pollutants, strong turbulence intermittency and the resulting turbulence barrier effect (i.e., a phenomenon that turbulence at certain heights may disappear forming a laminar flow as if there is a barrier layer impeding the vertical turbulent exchange) suppress the vertical diffusion of pollutants, leading to high PM2.5 concentrations. However, there are still some short-time removal processes of pollutants occurring at different heights in the CS, accompanied with interesting non-simultaneous drop or opposite variation of PM2.5 concentrations at different heights. The ubiquitous internal gravity waves (IGWs) in the stable boundary layer (SBL) may play a critical role in the above situation, as they are closely related to the intermittent turbulence bursts appearing in the persistent weak turbulent motions. In this study, two representative heavy haze pollution cases were chosen to demonstrate the above speculation using five layers of turbulence data, two layers of pressure fluctuations and three layers of PM2.5 concentrations. Results showed that the non-simultaneous drop or opposite variation of PM2.5 concentrations was associated with the destruction of turbulence barrier by the vertical propagation of IGWs. IGWs generated by some certain mechanisms, such as nonhomogeneous terrain and wind shear around the low-level jet (LLJ), can propagate upward or downward with the upward or downward development of the temperature inversion layer. The vertically propagating IGWs then triggered intermittent increasing turbulence layer by layer. Turbulence between layers reconnected sequentially and turbulence barriers were broken in turn. The enhanced turbulent exchange expedited the pollutant diffusion, thus the PM2.5 concentrations at different heights varied non-simultaneously even inversely. This study provides a good explanation for the positive effects of sub-mesoscale motions such as IGWs on triggering intermittent increasing turbulence and facilitating the diffusion of pollutants during heavy haze pollution events.

Modeling Studies of Gravity Wave Dynamics in Highly Structured Environments: Reflection, Trapping, Instability, Momentum Transport, Secondary Gravity Waves, and Induced Flow Responses.

A compressible numerical model is applied for three‐dimensional (3‐D) gravity wave (GW) packets undergoing momentum deposition, self‐acceleration (SA), breaking, and secondary GW (SGW) generation in the presence of highly‐structured environments enabling thermal and/or Doppler ducts, such as a mesospheric inversion layer (MIL), tidal wind (TW), or combination of MIL and TW. Simulations reveal that ducts can strongly modulate GW dynamics. Responses modeled here include reflection, trapping, suppressed transmission, strong local instabilities, reduced SGW generations, higher altitude SGW responses, and induced large‐scale flows. Instabilities that arise in ducts experience strong dissipation after they emerge, while trapped smaller‐amplitude and smaller‐scale GWs can survive in ducts to much later times. Additionally, GW breaking and its associated dynamics enhance the local wind along the GW propagation direction in the ducts, and yield layering in the wind field. However, these dynamics do not yield significant heat transport in the ducts. The failure of GW breaking to induce stratified layers in the temperature field suggests that such heat transport might not be as strong as previously assumed or inferred from observations and theoretical assessments. The present numerical simulations confirm previous finding that MIL generation may not be caused by the breaking of a transient high‐frequency GW packet alone.

Vertical profiles of O3, NO2 and PM in a major fine chemical industry park in the Yangtze River Delta of China detected by a sensor package on an unmanned aerial vehicle

The vertical profiles and diurnal variations of air pollutants at different heights in the fine chemical industry park (FCIP) were systematically studied in this study. Air pollutants in a major FCIP in the Yangtze River Delta of China within 500 m above ground level (AGL) detected by a sensor package on an unmanned aerial vehicle (UAV). The air pollutants including ozone (O3), nitrogen dioxide (NO2), particulate matter (PM), total volatile organic compounds (TVOCs) and carbon monoxide (CO), respectively, had been measured through more than one hundred times of vertical flights from Aug. 2020 to Jul. 2021. The concentrations of NO2 and CO generally decreased with the height while the concentrations of O3 increased with the height within 500 m AGL. The photochemical reaction resulted in a strong inverse relationship between the vertical profiles of O3 and that of NO2. The concentrations of PM2.5 and TVOCs generally decreased with the height below 100 m AGL and were fully mixed above 100 m AGL. The vertical profiles of different particle sizes were well consistent with the R2 value of 0.97 between PM1 and PM2.5 and 0.93 between PM2.5 and PM10. The NO2 and PM2.5 concentrations sometimes increased with height maybe due to the influence of temperature inversion layer or long-distance transportation from northern China. The diurnal variations of NO2, O3, TVOCs and CO concentrations at different heights within 500 m AGL were basically consistent. The diurnal variations range of PM2.5 concentrations below 100 m AGL was large and different from other heights, which should be greatly influenced by the local emissions. The unstable atmospheric stability was accompanied by strong photochemical reactions and convective activities, resulting in low concentrations of NO2 and PM2.5, while high concentrations of O3.

Modeling of the Calm Situations in the Atmosphere of Almaty

This article addresses modeling of the atmospheric boundary layer of the city of Almaty (Kazakhstan) in stagnant, environmentally unfavorable conditions using WRF Model. The city is located on the northern slope of Trans-Ili Alatau, where the rate of recurrence of calm and low-wind (1–2 m/sec) days reaches about 80%. All simulations were made for a period from 28.11.2016 to 05.12.2016, covering main synoptic situations of the stagnant atmosphere: the extent of Asian anticyclone, higher and lower pressure gradient fields. The model integrated three nested domains with grid sizes 9, 3 and 1 km, respectively. The initial boundary conditions were formed based on ERA5-reanalysis. Subject to the WRF model requirements, the land-use map with a standard USGS set (24 categories) was developed, to which 3 categories of the urban areas were added. The most relevant configuration of parameterization methods was selected: short-wave and long-wave radiation (Mlawer), surface layer (Monin-Obukhov similarity theory), urban area (BEP), boundary layer (Bougeault-Lacarrere), turbulence (Smagorinsky). The article demonstrates that the WRF model adequately reflects fundamental urban atmosphere patterns in the most unfavorable anticyclone periods of the autumn-winter season. It was established that the accuracy of estimates decreases with the transition to weak cyclonic activity. Based on the simulation results and remote sensing data, the territory in question is divided into four climatic zones to which a comparative method was applied; however for a detailed correlative analysis a denser network of meteorological stations is required. Calculations showed that the wind along the Ili river valley prevails in the northern part, regularly changing its western direction to eastern. Near the mountain area mountain-valley wind circulation prevails. The blocking inversion layer has a strong impact. The urban heat islands strongly depend on wind conditions. For example, a nocturnal heat island is cooled by the cold wind flow from the mountains.

Atmospheric conditions favorable for the creation of artificial clouds by a jet saturated with hygroscopic aerosol

The possibility of creating artificial clouds based on theoretical modeling of a vertically directed buoyancy jet was analyzed considering vertical temperature lapse rate, wind speed, relative humidity of the near-ground atmospheric layer, and thickness of the inversion layer. Numerical experiments demonstrated that a jet with an initial velocity of 300 m/s, the temperature of 300 °C, and flow volume of 240 m3/s without additional energy feeding can reach the condensation level in certain conditions, namely, absence of an inversion layer, vertical temperature lapse rate >8 °C/km, and humidity >85%. The introduction of three types of hygroscopic aerosols with different hygroscopic points into the jet and the replenishment of the jet energy with heat from the condensation of water vapor can expand the boundaries of favorable conditions for stimulating thermal convection and creating artificial clouds. The results can be used to develop criteria for choosing days with favorable conditions for conducting field experiments.

Observation of Gravity Wave Vertical Propagation through a Mesospheric Inversion Layer

The impact of a mesospheric temperature inversion on the vertical propagation of gravity waves has been investigated using OH airglow images and ground-based Rayleigh lidar measurements carried out in December 2017 at the Haute-Provence Observatory (OHP, France, 44N). These measurements provide complementary information that allows the vertical propagation of gravity waves to be followed. An intense mesospheric inversion layer (MIL) observed near 60 km of altitude with the lidar disappeared in the middle of the night, offering a unique opportunity to evaluate its impact on gravity wave (GW) propagation observed above the inversion with airglow cameras. With these two instruments, a wave with a 150 min period was observed and was also identified in meteorological analyses. The gravity waves’ potential energy vertical profile clearly shows the GW energy lost below the inversion altitude and a large increase of gravity wave energy above the inversion in OH airglow images with waves exhibiting higher frequency. MILs are known to cause instabilities at its top part, and this is probably the reason for the enhanced gravity waves observed above.

Phonon Symphony of Stacked Multilayers and Weak Bonds Lowers Lattice Thermal Conductivity.

Controlling lattice vibrations to obtain intrinsic low thermal conductivity play a critical role in thermal management of electronic and photonic devices, energy converters, and thermal insulation, which necessitates exploring new compounds and a thorough understanding of their chemical structure, bonding, and lattice dynamics. Herein, a new chalcogenide, Ga6 Cr5 Se16 , shows intrinsic low lattice thermal conductivity κlat , which crystallizes in the monoclinic phase (C2/m) with the stacked inverse GaSe4 layers (g'), close-packed Cr3+ Se6 layers (c), GaSe4 layers (g) and loosely-stacked Cr2+ Se6 layers (c') along the c-axis. In this structure, a wide variety of chemical bonding is arranged in each layer, such as covalent Ga-Se, covalent Cr3+ -Se, and weaker Cr2+ -Se bonding, which endow it with a large phonon symphony by strong coupling of soft acoustic and low-lying optical phonons. As a result, Ga6 Cr5 Se16 realizes an intrinsic low κlat of 0.79 W m- 1 K- 1 at 323 K, which is almost four times, or twice lower than that of Cr3 Se4 (2.95 W m- 1 K- 1 ), or Cr2 Se3 (1.56 W m- 1 K- 1 ), Ga2 Se3 (1.36 W m- 1 K- 1 ) at 323 K, respectively. These insights will offer comprehensive understanding of the phonon propagation in complex layered chalcogenides, andalso shed useful light on future design of low-κlat solids.

ICESAT-2 Lidar retrievals for a smoke and clouds case: estimates in the south america region

The present study aims to estimate the height of smoke aerosols and clouds from the Advanced Topographic Laser Altimeter System (ATLAS) instrument sensor onboard the Ice, Cloud and land Elevation Satellite-2 (ICESat-2). The study was conducted during the dry season on September 14th of 2020, when there was a large number spot of biomass burning fires and smoke aerosol layers over the Amazon and the South American region. Most often, the smoke plumes move with southward winds, along the east of the Andes. During this period occasionally polar cold fronts move from the south, meeting the smoke aerosol layers. Initially, daily images from the polar orbit satellites such as Terra, Aqua, NOAA and Suomi were used to identify the spatial location of smoke plumes and clouds over the region. Then, ICESat-2 tracks were analyzed to evaluate their presence in the study area. The results show that ICESat-2 data retrieval is able to estimate the height of the aerosol layer and the top of the cloud. Some tracks show clearly higher clouds, with tops reaching about 12-13 km, when there is the presence of a cold front or deep convective cumulonimbus. Over clear sky regions where smoke is observed, estimated heights from the lidar are on the order of 3-4 km. Local profiles of temperature obtained from radiosondes show inversion layers at similar heights as detected by the lidar sensor. These inversion layers seem to be associated with the warming effect of the absorbing biomass burning aerosols.

Tropopause Characteristics Based on Long-Term ARM Radiosonde Data: A Fine-Scale Comparison at the Extratropical SGP Site and Arctic NSA Site

The variations in the characteristics of the tropopause are sensitive indicators for the climate system and climate change. By using Atmospheric Radiation Measurement (ARM) radiosonde data that were recorded at the extratropical Southern Great Plains (SGP) and Arctic North Slope of Alaska (NSA) sites over an 18-year period (January 2003 to December 2020), this study performs a fine-scale comparison of the climatological tropopause features between these two sites that are characterized by different climates. The static stability increases rapidly above the tropopause at both sites, indicating the widespread existence of a tropopause inversion layer. The structures of both the tropopause inversion layer and the stability transition layer are more obvious at NSA than at SGP, and the seasonal variation trends of the tropopause inversion layer and stability transition layer are distinctly different between the two sites. A fitting method was used to derive the fitted tropopause height and tropopause sharpness (λ). Although this fitting method may determine a secondary tropopause rather than the primary tropopause when multiple tropopause heights are identified on one radiosonde profile, the fitted tropopause heights generally agree well with the observed tropopause heights. Broad tropopause sharpness values (λ > 2 km) occur more frequently at SGP than at NSA, resulting in a greater average tropopause sharpness at SGP (1.0 km) than at NSA (0.6 km). Significant positive trends are exhibited by the tropopause heights over the two sites, with rates of increase of 23.7 ± 6.5 m yr−1 at SGP and 28.0 ± 4.0 m yr−1 at NSA during the study period.

Three-dimensional structure and transport pathways of dust aerosols over West Asia

AbstractThis study investigates the seasonal climatology of the three-dimensional distribution and transport pathways of dust aerosols over West Asia (WA). Dust column loading over WA exhibits strong seasonality, with markedly high (weak) loading during summer (winter). The summer dust features over WA include the (i) dust reaching up to the 500 hPa level between the Red Sea (RS) and the west coast of the Indian subcontinent (IS); (ii) a slantwise advection of dust aerosols between 850 and 700 hPa levels over the Arabian Peninsula (AP) and Arabian Sea (AS); and (iii) a prominent mid-tropospheric zonal transport of AP dust toward the IS. Maximum column integrated horizontal dust mass flux (DMF) over WA is observed in summer. The intraday changes in the intensity and spatial spread of the DMF over the AP are mediated by the out-of-phase evolution of the surface winds and low-level Shamal jets. Furthermore, the diurnal changes in the strength of the inversion layers located above the monsoon boundary layer and associated wind shear regulate the spatial patterns and intensity of the DMF over the AS. The findings will support future studies aiming at quantifying the radiative effects of dust on the regional climate.

Hole‐Selective Ultrathin Al‐Doped SiOxPassivation Layer Formed by Immersing in Aluminum Nitrate Aqueous Solution

Herein, ultrathin Al‐doped SiOxlayer formed by immersing in Al(NO3)3aqueous solution is introduced. This layer enables high‐level surface passivation with a maximum effective surface recombination velocity (Seff,max) < 16 cm s−1at an excess carrier density (Δn) of 1 × 1015 cm−3for 2.5 Ω cm n‐type c‐Si without any other processes such as film deposition in a vacuum chamber, high‐temperature annealing, and hydrogenation. This passivation effect presumably comes from negative fixed charges localized in Al‐doped SiOxlayers, forming inversion layers due to upward Si band bending at the SiOx/Si interface. In addition, the Al‐doped SiOxlayers facilitate accumulated holes at the interface to tunnel through the layers even though the applied bias is extremely low. The high tunnel current density of holes accumulated in the inversion layers implies that these ultrathin Al‐doped SiOxlayers are expected to be favorably implemented for high‐efficiency passivating‐contact c‐Si solar cells.

Updated Climatology of Mesospheric Temperature Inversions Detected by Rayleigh Lidar above Observatoire de Haute Provence, France, Using a K-Mean Clustering Technique

A climatology of Mesospheric Inversion Layers (MIL) has been created using the Rayleigh lidar located in the south of France at L’Observatoire de Haute Provence (OHP). Using criteria based on lidar measurement uncertainties and climatological mean gravity wave amplitudes, we have selected significant large temperature anomalies that can be associated with MILs. We have tested a novel approach for classifying MILs based on a k-mean clustering technique. We supplied different parameters such as the MIL amplitudes, altitudes, vertical extension, and lapse rate and allowed the computer to classify each individual MIL into one of three clusters or classes. For this first proof of concept study, we selected k = 3 and arrived at three distinct MIL clusters, each of which can be associated with different processes generating MILs in different regimes. All clusters of MIL exhibit a strong seasonal cycle with the largest occurrence in winter. The four decades of measurements do not reveal any long-term changes that can be associated with climate changes and only show an inter-annual variability with a quasi-decadal oscillation.

Optical resonance in the inversion [formula omitted] channel of a silicon MOS structure

The features of the manifestation of the self-induced transparency (SIT) effect at intersubband resonance in the inversion n− layer of silicon semiconductor systems (in field-effect transistors (100)Si−MOSFET) are analyzed. The course of the interaction of ultrashort laser pulses with the quantum states of the inversion layer of the MOS structure varies, depending on the concentration of the induced charge, by changing the voltage across the metal gate. The evolution of a pulse in the transient stage of deformation as it propagates in a resonant medium of an inversion channel is discussed. Possible consequences for a non-degenerate one-photon resonance are considered, with controlled changes in the detuning between a fixed pulse frequency and the resonant energy of the intersubband transition, caused by changes in the charge density. The parametric dependence on the concentration of the induced charges in the “area theorem” for the propagation process in the inversion channel is revealed.

Detecting nighttime inversions in the interior of a Douglas fir canopy

Despite the importance of forests in the water and carbon cycles, accurately measuring their contribution remains challenging, especially at night. During clear-sky nights current models and theories fail, as non-turbulent flows and spatial heterogeneity become more important. One of the standing issues is the ‘decoupling’ of the air masses in and above the canopy, where little turbulent exchange takes place, thus preventing proper measurement of atmospheric fluxes. Temperature inversions, where lower air is colder and thus more dense, can be both the cause and result of this decoupling.With Distributed Temperature Sensing (DTS) it is now possible to detect these temperature inversions, and increase our understanding of the decoupling mechanism. With DTS we detected strong inversions within the canopy of a tall Douglas Fir stand. The inversions formed in on clear-sky nights with low turbulence, and preferentially formed in the open understory. A second inversion regularly occurred above the canopy. Oscillations in this upper inversion transferred vertically through the canopy and induced oscillations in the lower inversion.We hypothesize that the inversions could form due to a local suppression of turbulent motions along the height of the canopy. This was supported by a 1-D conceptual model, which showed that a local inversion layer would always form within the canopy if the bulk inversion (over the full canopy) was strong enough.Due to the near-continuous vertical motion and specific height the inversions occur at, a very high measurement density (better than ∼2 m) and measurement frequency (>0.1 Hz) are required to detect them. Consequently, it could be possible that the observed inversions are a regular feature in similarly structured forests, but are generally not directly observed. With DTS it is possible to detect and describe these types of features, which will aid in improving our understanding of atmospheric flows over complex terrain such as forests.