scholarly journals A powerful lidar system capable of 1 h measurements of water vapour in the troposphere and the lower stratosphere as well as the temperature in the upper stratosphere and mesosphere

2021 ◽  
Vol 14 (1) ◽  
pp. 531-555
Author(s):  
Lisa Klanner ◽  
Katharina Höveler ◽  
Dina Khordakova ◽  
Matthias Perfahl ◽  
Christian Rolf ◽  
...  
Keyword(s):  
Water Vapour ◽  
High Power ◽  
Average Power ◽  
Research Station ◽  
Raman Lidar ◽  
Signal Averaging ◽  
Lidar System ◽  
Wide Range ◽  
Linearly Polarized ◽  
Uncertainty Level

Abstract. A high-power Raman lidar system has been installed at the high-altitude research station Schneefernerhaus (Garmisch-Partenkirchen, Germany) at 2675 ma.s.l., at the side of an existing wide-range differential absorption lidar (DIAL). An industrial XeCl laser was modified for linearly polarized single-line operation at an average power of about 180 W. This high power and a 1.5 m diameter receiver allow us to extend the operating range for water-vapour sounding to 20 km for a measurement time of just 1 h, at an uncertainty level of the mixing ratio of 1 to 2 ppm. This was achieved for a vertical resolution varied between just 0.2 and 0.6 km in the stratosphere. The lidar was successfully validated with a balloon-borne cryogenic frost-point hygrometer (CFH). In addition, temperature measurements up to altitudes of around 87 km were demonstrated for 1 h of signal averaging. The system has been calibrated with the DIAL, the CFH and radiosondes.

scholarly journals A powerful lidar system capable of one-hour measurements of water vapour in the troposphere and the lower stratosphere as well as the temperature in the upper stratosphere and mesosphere

2020 ◽  
Author(s):  
Lisa Klanner ◽  
Katharina Höveler ◽  
Dina Khordakova ◽  
Matthias Perfahl ◽  
Christian Rolf ◽  
...  
Keyword(s):  
Water Vapour ◽  
High Power ◽  
Average Power ◽  
Research Station ◽  
Raman Lidar ◽  
Signal Averaging ◽  
Lidar System ◽  
Wide Range ◽  
Linearly Polarized ◽  
Uncertainty Level

Abstract. A high-power Raman lidar system has been installed at the high-altitude research station Schneefernerhaus (Garmisch-Partenkirchen, Germany) at 2675 m a.s.l., at the side of an existing wide-range differential-absorption lidar (DIAL). An industrial XeCl laser was modified for linearly polarized single-line operation at an average power of about 180 W. This high power and a 1.5-m-diameter receiver allow us to extend the operating range for water-vapour sounding to 20 km within one hour, at an uncertainty level of the mixing ratio of 1 to 2 ppm. This was achieved for a vertical resolution varied between just 0.2 and 0.6 km in the stratosphere and could be improved for stronger smoothing. The lidar was successfully validated with a balloon-borne cryogenic frost-point hygrometer (CFH). In addition, temperature measurements to altitudes around 87 km were demonstrated for one hour of signal averaging. The system has been calibrated with the DIAL, the CFH and radiosondes.

scholarly journals Water-vapour measurements up to the lower stratosphere — the high power raman lidar at the schneefernerhaus

2018 ◽  
Vol 176 ◽  
pp. 01026 ◽  
Author(s):  
Lisa Klanner ◽  
Thomas Trickl ◽  
Hannes Vogelmann
Keyword(s):  
High Power ◽  
Lower Stratosphere ◽  
Research Station ◽  
Xecl Laser ◽  
Raman Lidar ◽  
Differential Absorption ◽  
Lidar System ◽  
Backscatter Signal ◽  
Vertical Range ◽  
Accuracy Level

A high-power Raman lidar system has been developed at the high-altitude research station Schneefernerhaus (Garmisch-Partenkirchen, Germany) at 2675 m, at the side of an existing differential-absorption lidar. It is based on a 180-W single-line XeCl laser and on two Newtonian telescopes (up to 1.5-m-diameter). In this way a vertical range up to more than 20 km and an accuracy level of the order of 10 % can be achieved for a measurement time of 1 h. Temperature measurements have been demonstrated to altitudes up to 54 km with just 1 % of the full 308-nm backscatter signal. Significantly higher altitudes are expected when using a chopper that cuts off the first 10 km or for 353 nm.

scholarly journals Characterization of atmospheric thermodynamic variables by Raman lidar in the frame of the International Network for the Detection of Atmospheric Composition Change - NDACC

2018 ◽  
Vol 176 ◽  
pp. 04010
Author(s):  
Benedetto De Rosa ◽  
Paolo Di Girolamo ◽  
Donato Summa
Keyword(s):  
Water Vapour ◽  
Atmospheric Temperature ◽  
Atmospheric Composition ◽  
Vertical Profiles ◽  
Mixing Ratio ◽  
Composition Change ◽  
Raman Lidar ◽  
Lidar System ◽  
Thermodynamic Variables

In November 2012 the Raman Lidar system BASIL, located at the Univ. of Basilicata (Potenza), was approved to enter in NDACC, with the goal of providing accurate routine measurements of the vertical profiles of atmospheric temperature and water vapour mixing ratio. In this presentation we illustrate and discuss water vapour mixing ratio and temperature measurements carried out during these four years and their comparisons with the radiosondes launched from nearby Institute IMAA-CNR (7 km away).

scholarly journals Reactive High-Power Impulse Magnetron Sputtering of Chromium-Carbon Films

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1269
Author(s):  
Chin-Chiuan Kuo ◽  
Chun-Hui Lin ◽  
Jing-Tang Chang ◽  
Yu-Tse Lin
Keyword(s):  
Magnetron Sputtering ◽  
Amorphous Carbon ◽  
High Power ◽  
Deposition Temperature ◽  
Average Power ◽  
Carbon Films ◽  
Strengthening Effect ◽  
Substrate Bias ◽  
Hydrogenated Amorphous Carbon ◽  
Hydrogenated Amorphous

Chromium-carbon films were deposited by utilizing reactive high-power impulse magnetron sputtering at different mixture ratios of ethyne and argon atmosphere, and different substrate bias voltages and deposition temperature, with the same pulse frequency, duty cycle, and average power. The microstructure and mechanical properties of the obtained films were compared. The films consist of amorphous or nanocrystalline chromium carbide, hydrogenated amorphous carbon, and minor α-chromium phase. Decreasing the fraction of ethyne increases the content of the α-chromium phase but decreases hydrogenated amorphous carbon phase. The film’s hardness increases by enhancing the negative substrate bias and raising the deposition temperature, which could be attributed to the increase of film density and the Hall–Petch strengthening effect induced by the nanoscale crystallization of the amorphous carbide phase.

A LOW DROPOUT REGULATOR WITH LOW QUIESCENT CURRENT AND HIGH POWER SUPPLY REJECTION OVER WIDE RANGE OF FREQUENCY FOR SOC

2011 ◽  
Vol 20 (01) ◽  
pp. 1-13 ◽  
Author(s):  
CHENCHANG ZHAN ◽  
WING-HUNG KI
Keyword(s):  
High Power ◽  
Power Supply ◽  
Cmos Process ◽  
High Loop ◽  
Wide Range ◽  
Quiescent Current ◽  
Low Dropout Regulator ◽  
Output Capacitor ◽  
Large Output ◽  
Supply Rejection

A CMOS low quiescent current low dropout regulator (LDR) with high power supply rejection (PSR) and without large output capacitor is proposed for system-on-chip (SoC) power management applications. By cascoding a power NMOS with the PMOS pass transistor, high PSR over a wide frequency range is achieved. The gate-drive of the cascode NMOS is controlled by an auxiliary LDR that draws only 1 μA from a small charge pump, thus helping in reducing the quiescent current. Adaptive biasing is employed for the multi-stage error amplifier of the core LDR to achieve high loop gain hence high PSR at low frequency, low quiescent current at light load and high bandwidth at heavy load. A prototype of the proposed high-PSR LDR is fabricated using a standard 0.35 μm CMOS process, occupying an active area of 0.066 mm2. The lowest supply voltage is 1.6 V and the preset output voltage is 1.2 V. The maximum load current is 10 mA. The measured worst-case PSR at full load without using large output capacitor is -22.7 dB up to 60 MHz. The line and load regulations are 0.25 mV/V and 0.32 mV/mA, respectively.

scholarly journals One year of Raman lidar observations of free-tropospheric aerosol layers over South Africa

2015 ◽  
Vol 15 (10) ◽  
pp. 5429-5442 ◽  
Author(s):  
E. Giannakaki ◽  
A. Pfüller ◽  
K. Korhonen ◽  
T. Mielonen ◽  
L. Laakso ◽  
...  
Keyword(s):  
South Africa ◽  
Optical Properties ◽  
Biomass Burning ◽  
Mean Value ◽  
Aerosol Layer ◽  
Raman Lidar ◽  
Tropospheric Aerosol ◽  
Wide Range ◽  
Significant Difference ◽  
532 Nm

Abstract. Raman lidar data obtained over a 1 year period has been analysed in relation to aerosol layers in the free troposphere over the Highveld in South Africa. In total, 375 layers were observed above the boundary layer during the period 30 January 2010 to 31 January 2011. The seasonal behaviour of aerosol layer geometrical characteristics, as well as intensive and extensive optical properties were studied. The highest centre heights of free-tropospheric layers were observed during the South African spring (2520 ± 970 m a.g.l., also elsewhere). The geometrical layer depth was found to be maximum during spring, while it did not show any significant difference for the rest of the seasons. The variability of the analysed intensive and extensive optical properties was high during all seasons. Layers were observed at a mean centre height of 2100 ± 1000 m with an average lidar ratio of 67 ± 25 sr (mean value with 1 standard deviation) at 355 nm and a mean extinction-related Ångström exponent of 1.9 ± 0.8 between 355 and 532 nm during the period under study. Except for the intensive biomass burning period from August to October, the lidar ratios and Ångström exponents are within the range of previous observations for urban/industrial aerosols. During Southern Hemispheric spring, the biomass burning activity is clearly reflected in the optical properties of the observed free-tropospheric layers. Specifically, lidar ratios at 355 nm were 89 ± 21, 57 ± 20, 59 ± 22 and 65 ± 23 sr during spring (September–November), summer (December–February), autumn (March–May) and winter (June–August), respectively. The extinction-related Ångström exponents between 355 and 532 nm measured during spring, summer, autumn and winter were 1.8 ± 0.6, 2.4 ± 0.9, 1.8 ± 0.9 and 1.8 ± 0.6, respectively. The mean columnar aerosol optical depth (AOD) obtained from lidar measurements was found to be 0.46 ± 0.35 at 355 nm and 0.25 ± 0.2 at 532 nm. The contribution of free-tropospheric aerosols on the AOD had a wide range of values with a mean contribution of 46%.

Energy Harvesting From the Vibrations of Rotating Systems

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Christopher G. Cooley ◽  
Tan Chai
Keyword(s):  
Rotation Speed ◽  
Excitation Frequency ◽  
Average Power ◽  
Local Maximum ◽  
Operating Conditions ◽  
Centripetal Acceleration ◽  
Local Maxima ◽  
Closed Form Solutions ◽  
Energy Harvesters ◽  
Wide Range

This study investigates the vibration of and power harvested by typical electromagnetic and piezoelectric vibration energy harvesters when applied to vibrating host systems that rotate at constant speed. The governing equations for these electromechanically coupled devices are derived using Newtonian mechanics and Kirchhoff's voltage law. The natural frequency for these devices is speed-dependent due to the centripetal acceleration from their constant rotation. Resonance diagrams are used to identify excitation frequencies and speeds where these energy harvesters have large amplitude vibration and power harvested. Closed-form solutions are derived for the steady-state response and power harvested. These devices have multifrequency dynamic response due to the combined vibration and rotation of the host system. Multiple resonances are possible. The average power harvested over one oscillation cycle is calculated for a wide range of operating conditions. Electromagnetic devices have a local maximum in average harvested power that occurs near a specific excitation frequency and rotation speed. Piezoelectric devices, depending on their mechanical damping, can have two local maxima of average power harvested. Although these maxima are sensitive to small changes in the excitation frequency, they are much less sensitive to small changes in rotation speed.

scholarly journals Tropospheric water vapour and relative humidity profiles from lidar and microwave radiometry

2014 ◽  
Vol 7 (5) ◽  
pp. 1201-1211 ◽  
Author(s):  
F. Navas-Guzmán ◽  
J. Fernández-Gálvez ◽  
M. J. Granados-Muñoz ◽  
J. L. Guerrero-Rascado ◽  
J. A. Bravo-Aranda ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Microwave Radiometer ◽  
Radiosonde Data ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Night Time ◽  
New Approach ◽  
Lidar Measurements ◽  
Humidity Profiles

Abstract. In this paper, we outline an iterative method to calibrate the water vapour mixing ratio profiles retrieved from Raman lidar measurements. Simultaneous and co-located radiosonde data are used for this purpose and the calibration results obtained during a radiosonde campaign in summer and autumn 2011 are presented. The water vapour profiles measured during night-time by the Raman lidar and radiosondes are compared and the differences between the methodologies are discussed. Then, a new approach to obtain relative humidity profiles by combination of simultaneous profiles of temperature (retrieved from a microwave radiometer) and water vapour mixing ratio (from a Raman lidar) is addressed. In the last part of this work, a statistical analysis of water vapour mixing ratio and relative humidity profiles obtained during 1 year of simultaneous measurements is presented.

scholarly journals Chemical and physical characteristics of aerosol particles at a remote coastal location, Mace Head, Ireland, during NAMBLEX

2006 ◽  
Vol 6 (11) ◽  
pp. 3289-3301 ◽  
Author(s):  
H. Coe ◽  
J. D. Allan ◽  
M. R. Alfarra ◽  
K. N. Bower ◽  
M. J. Flynn ◽  
...  
Keyword(s):  
Surf Zone ◽  
Organic Aerosol ◽  
Sea Salt ◽  
Research Station ◽  
Aerosol Composition ◽  
Gaseous Species ◽  
Accumulation Mode ◽  
Coarse Mode ◽  
Wide Range ◽  
Loss Rates

Abstract. A suite of aerosol physical and chemical measurements were made at the Mace Head Atmospheric Research Station, Co. Galway, Ireland, a coastal site on the eastern seaboard of the north Atlantic Ocean during NAMBLEX. The data have been used in this paper to show that over a wide range of aerosol sizes there is no impact of the inter-tidal zone or the surf zone on measurements made at 7 m above ground level or higher. During the measurement period a range of air mass types were observed. During anticyclonic periods and conditions of continental outflow Aitken and accumulation mode were enhanced by a factor of 5 compared to the marine sector, whilst coarse mode particles were enhanced during westerly conditions. Baseline marine conditions were rarely met at Mace Head during NAMBLEX and high wind speeds were observed for brief periods only. The NAMBLEX experiment focussed on a detailed assessment of photochemistry in the marine environment, investigating the linkage between the HOx and the halogen radical cycles. Heterogeneous losses are important in both these cycles. In this paper loss rates of gaseous species to aerosol surfaces were calculated for a range of uptake coefficients. Even when the accommodation coefficient is unity, lifetimes due to heterogeneous loss of less than 10 s were never observed and rarely were they less than 500 s. Diffusional limitation to mass transfer is important in most conditions as the coarse mode is always significant. We calculate a minimum overestimate of 50% in the loss rate if this is neglected and so it should always be considered when calculating loss rates of gaseous species to particle surfaces. HO2 and HOI have accommodation coefficients of around 0.03 and hence we calculate lifetimes due to loss to particle surfaces of 2000 s or greater under the conditions experienced during NAMBLEX. Aerosol composition data collected during this experiment provide representative information on the input aerosol characteristics to western Europe. During NAMBLEX the submicron aerosol was predominately acidified sulphate and organic material, which was most likely internally mixed. The remaining accumulation mode aerosol was sea salt. The organic and sulphate fractions were approximately equally important, though the mass ratio varies considerably between air masses. Mass spectral fingerprints of the organic fraction in polluted conditions are similar to those observed at other locations that are characterised by aged continental aerosol. In marine conditions, the background input of both sulphate and organic aerosol into Europe was observed to be between 0.5 and 1 µg m−3. Key differences in the mass spectra were observed during the few clean periods but were insufficient to ascertain whether these changes reflect differences in the source fingerprint of the organic aerosol. The coarse mode was composed of sea salt and showed significant displacement of chloride by nitrate and to a lesser extent sulphate in polluted conditions.

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