scholarly journals Statistical Characterization of Temperature and Pressure Vertical Profiles for the Analysis of Laser Heterodyne Radiometry Data

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5421
Author(s):  
Monica M. Flores ◽  
David S. Bomse ◽  
J. Houston Miller
Keyword(s):  
Probability Distributions ◽  
Lower Atmosphere ◽  
Temperature Profiles ◽  
Time Data ◽  
Statistical Characterization ◽  
Line Shapes ◽  
Pressure Profiles ◽  
Laser Heterodyne ◽  
Temperature And Pressure ◽  
Heterodyne Radiometry

The statistical analysis of historic pressure and temperature profiles from radiosonde launches for use in the fitting of molecular oxygen line shapes is presented. As the O2 mixing ratio is nearly constant throughout the lower atmosphere, only variations in pressure and temperature profiles will affect the fit of observed O2 features in Laser Heterodyne Radiometry (LHR) spectra. Radiosonde temperature and pressure data are extracted from the Integrated Global Radiosonde Archive (IGRA) for a given station, date, and launch time. Data may be extracted for a single launch, for the same date over several years, and/or within a window centered on a target date. The temperature and pressure profiles are further characterized by the statistical variation in coefficients of polynomial fits in altitude. The properties of the probability distributions for each coefficient are used to constrain fits of O2 line shapes through Nelder–Mead optimization. The refined temperature and pressure profiles are then used in the retrieval of vertically resolved mixing ratios for greenhouse gases (GHGs) measured in the same instrument. In continuous collections, each vertical profile determination may be treated as a Bayesian prior to inform subsequent measurements and provide an estimate of uncertainties.

Statistical Characterization of Temperature and Pressure Vertical Profiles for the Analysis of Laser Heterodyne Data

2021 ◽  
Author(s):  
J. Houston Miller ◽  
Monica Flores ◽  
David Bomse
Keyword(s):  
Probability Distributions ◽  
Time Of Day ◽  
George Washington ◽  
Statistical Characterization ◽  
Mixing Ratios ◽  
Line Shapes ◽  
Pressure Profiles ◽  
Historic Data ◽  
Laser Heterodyne ◽  
Temperature And Pressure

<div>We present an analysis of historic pressure and temperature profiles from radiosonde</div><div>launches that will be used in retrieval of mixing fractions for greenhouse gases (GHGs, including</div><div>carbon dioxide, methane, and water vapor) in Laser Heterodyne Radiometry (LHR) data. With</div><div>over 2,700 stations worldwide, the global coverage for weather balloon observations is</div><div>extensive. Radiosonde stations included in the Integrated Global Radiosonde Archive (IGRA),</div><div>are launched simultaneously twice daily at 00:00 and 12:00 UTC. Global stations span all time</div><div>zones in both the Northern and Southern Hemisphere.</div><div> </div><div>Mesa Photonics and George Washington University are developing a variant of LHR</div><div>known as Precision Heterodyne, Oxygen-Corrected Spectroscopy (PHOCS) that simultaneously</div><div>collects high-resolution, oxygen spectral line shape data. Because oxygen concentrations in the</div><div>troposphere and lower stratosphere are constant, these line shapes are uniquely sensitive to both</div><div>temperature and pressure profiles and constrained fitting of these line shapes enables more</div><div>precise GHG concentration retrievals.</div><div> </div><div>Our approach is to collect historic data over several years (typically the prior decade) for</div><div>a particular date window surrounding a PHOCS measurement date for stations across the globe,</div><div>and mine this data for observation probability distributions as a function of level altitude, local</div><div>time of day of launch, latitude, etc. These distributions will then be used as Bayesian priors to</div><div>constrain temperature and pressure fits during the oxygen spectral fitting routine. Subsequently,</div><div>these priors will be used to estimate uncertainties in vertically-resolved GHG mixing ratios.</div>

scholarly journals Subcritical Transmission in the Early Stage of COVID-19 in Korea

2021 ◽  
Vol 18 (3) ◽  
pp. 1265
Author(s):  
Yong Sul Won ◽  
Jong-Hoon Kim ◽  
Chi Young Ahn ◽  
Hyojung Lee
Keyword(s):  
Incubation Period ◽  
Early Stage ◽  
Probability Distributions ◽  
Likelihood Estimation ◽  
Contact Tracing ◽  
Statistical Characterization ◽  
Serial Interval ◽  
Imported Cases ◽  
The Mean ◽  
Reporting Delays

While the coronavirus disease 2019 (COVID-19) outbreak has been ongoing in Korea since January 2020, there were limited transmissions during the early stages of the outbreak. In the present study, we aimed to provide a statistical characterization of COVID-19 transmissions that led to this small outbreak. We collated the individual data of the first 28 confirmed cases reported from 20 January to 10 February 2020. We estimated key epidemiological parameters such as reporting delay (i.e., time from symptom onset to confirmation), incubation period, and serial interval by fitting probability distributions to the data based on the maximum likelihood estimation. We also estimated the basic reproduction number (R0) using the renewal equation, which allows for the transmissibility to differ between imported and locally transmitted cases. There were 16 imported and 12 locally transmitted cases, and secondary transmissions per case were higher for the imported cases than the locally transmitted cases (nine vs. three cases). The mean reporting delays were estimated to be 6.76 days (95% CI: 4.53, 9.28) and 2.57 days (95% CI: 1.57, 4.23) for imported and locally transmitted cases, respectively. The mean incubation period was estimated to be 5.53 days (95% CI: 3.98, 8.09) and was shorter than the mean serial interval of 6.45 days (95% CI: 4.32, 9.65). The R0 was estimated to be 0.40 (95% CI: 0.16, 0.99), accounting for the local and imported cases. The fewer secondary cases and shorter reporting delays for the locally transmitted cases suggest that contact tracing of imported cases was effective at reducing further transmissions, which helped to keep R0 below one and the overall transmissions small.

Precision Solar Spectroscopy with Near Infrared Laser Heterodyne Radiometry

2021 ◽  
Author(s):  
Connor Fredrick ◽  
Ryan Terrien ◽  
Suvrath Mahadevan ◽  
Franklyn Quinlan ◽  
Scott Diddams
Keyword(s):  
Near Infrared ◽  
Infrared Laser ◽  
Laser Heterodyne ◽  
Heterodyne Radiometry

scholarly journals Diurnal Variations of CO2 Mixing Ratio in the Lower Atmosphere by Three Wavelength DIAL

2020 ◽  
Vol 237 ◽  
pp. 03011
Author(s):  
Yasukuni Shibata ◽  
Chikao Nagasawa ◽  
Makoto Abo
Keyword(s):  
Solar Radiation ◽  
Diurnal Variation ◽  
Diurnal Variations ◽  
The Other ◽  
Lower Atmosphere ◽  
Temperature Profiles ◽  
Mixing Ratio ◽  
Other Hand

We have conducted the measurement of high accurate CO2 mixing ratio profiles by measuring the temperature profiles simultaneously using the three wavelength CO2 DIAL. The measurements of CO2 diurnal variation in the lower atmosphere were carried out on sunny and cloudy days respectively. We find out that increasing of the CO2 mixing ratio occurs over the altitude of about 2 km from the surface during nighttime. On the other hand, the CO2 mixing ratio decreases over the lower atmosphere during daytime. In particular, the CO2 mixing ratio decreases earlier on sunny days than on cloudy days after sunrise. This result suggests that CO2 absorption by photosynthesis greatly contributes to the strength of the solar radiation.

Numerical Analysis of Flow and Heat Transfer Characteristics on Micro Couette Flow

2014 ◽  
Vol 960-961 ◽  
pp. 551-554
Author(s):  
Lei Huang ◽  
Yang Cui
Keyword(s):  
Shear Stress ◽  
Couette Flow ◽  
Velocity Slip ◽  
Flow And Heat Transfer ◽  
Knudsen Numbers ◽  
Pressure Profiles ◽  
Viscous Heat ◽  
Temperature And Pressure ◽  
In The Beginning ◽  
Stream Direction

In this paper, Couette flow is mainly discussed by studying the general flow behaviour mechanism and importing the velocity slip and temperature jump boundary condition. By analyzing velocity, temperature and pressure profiles at different Knudsen numbers, we concluded that Couette flow is driven by shear stress. The shear stress lies in stream direction. Viscous heat causes the increasing of the fluid’s temperature. With the increasing of Knudsen numbers, the increasing speed increases. It’s in the beginning of transition region that the heat flux has the maximum.

scholarly journals Evaluation of laser heterodyne radiometry for numerical weather prediction applications

2018 ◽  
Vol 144 (715) ◽  
pp. 1831-1850 ◽  
Author(s):  
Fiona Smith ◽  
Stephan Havemann ◽  
Alex Hoffmann ◽  
William Bell ◽  
Damien Weidmann ◽  
...  
Keyword(s):  
Numerical Weather Prediction ◽  
Weather Prediction ◽  
Numerical Weather ◽  
Laser Heterodyne ◽  
Heterodyne Radiometry

scholarly journals Application of Neural Networks for Retrieval of the CO2 Concentration at Aerospace Sensing by IPDA-DIAL lidar

2019 ◽  
Vol 11 (6) ◽  
pp. 659 ◽  
Author(s):  
Gennadii G Matvienko ◽  
and Alexander Ya Sukhanov
Keyword(s):  
Neural Networks ◽  
Co2 Concentration ◽  
Surface Concentration ◽  
Average Concentration ◽  
Differential Absorption ◽  
Near Surface ◽  
Sources And Sinks ◽  
Pressure Profiles ◽  
Temperature And Pressure ◽  
Fully Connected

Greenhouse gas concentrations are increasing over the past few decades, creating the need to measure their concentration with high accuracy, including for determining their trends, sources, and sinks. In this regard, various methods of regional and global control are being developed. One of the measuring methods is passive satellite method, but they allow for you to get data mainly during the day and outside the poles of the Earth. Another method is active lidar; they require the consideration of various aspects that are related to the technical characteristics of the lidar and methods for solving inverse problems. This article discusses the possibility of using lidars for sensing carbon dioxide from space (orbit 450 km) and from a height of 10 km and 23 km, which presumably corresponds to the aircrafts and balloons. As a method of solving the inverse problem, the method of fully connected neural networks with three layers and pre-training of first layer is considered, allowing for the application of additional data, including the IPDA (Integrated Path Differential Absorption) signal, the scattered DIAL (Differential Absorption Lidar) signal, temperature, and pressure profiles. These estimates show the possibility of measuring the average concentration from an orbit height of 450 km with an error of 0.16%, a resolution of 60 km, with a 50 mJ laser pulse energy, and 1 m diameter telescope. It is also shown that it is possible to obtain the concentration profile, including the near-surface concentration with an error of 2 ppm.

The Effects of Oil Supply Pressure at different Groove Position on Temperature and Pressure Profile in Journal Bearing

2013 ◽  
Vol 66 (3) ◽  
Author(s):  
Mohamad Ali Ahmad ◽  
Salmiah Kasolang ◽  
R. S. Dwyer-Joyce ◽  
Aidah Jumahat
Keyword(s):  
Journal Bearing ◽  
Pressure Profile ◽  
Diameter Ratio ◽  
Radial Load ◽  
Oil Supply ◽  
Supply Pressure ◽  
Pressure Profiles ◽  
Hydrodynamic Journal Bearing ◽  
Temperature And Pressure ◽  
Length To Diameter Ratio

The effects of oil supply pressure on the temperature and pressure at different groove locations on a hydrodynamic journal bearing were investigated. A journal with a diameter of 100 mm and a ½ length-to-diameter ratio was used. The supply pressure was set to 0.2, 0.5, and 0.7 MPa at seven different groove locations, namely, -45°, -30°, -15°, 0°, +15°, +30°, and +45°. Temperature and pressure profiles were measured at speed values of 300, 500, and 800 rpm with 10 kN radial load. The results show that the change in oil supply pressure simultaneously reduced the temperature and increased the pressure profile.

Low-cost flow-rate estimate in separate layers along gas wells from temperature and pressure profiles

2013 ◽  
Vol 53 (1) ◽  
pp. 285
Author(s):  
Emile Barrett ◽  
Imran Abbasy ◽  
Chii-Rong Wu ◽  
Zhenjiang You ◽  
Pavel Bedrikovetsky
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Flow Rate ◽  
Low Cost ◽  
Pressure Sensors ◽  
Gas Wells ◽  
Production Rates ◽  
Pressure Profiles ◽  
Temperature And Pressure ◽  
The Mathematical Model

Estimation of rate profile along the well is important information for reservoir characterisation since it allows distinction of the production rates from different layers. The temperature and pressure sensors in a well are small and inexpensive; while flow meters are cumbersome and expensive, and affect the flow in the well. The method presented in this peer-reviewed paper shows its significance in predicting the gas rate from temperature and pressure data. A mathematical model for pressure and temperature distributions along a gas well has been developed. Temperature and pressure profiles from nine well intervals in field A (Cooper Basin, Australia) have been matched with the mathematical model to determine the flow rates from different layers in the well. The presented model considers the variables as functions of thermal properties at each location, which is more accurate and robust than previous methods. The results of tuning the mathematical model to the field data show good agreement with the model prediction. Simple and robust explicit formulae are derived for the effective estimation of flow rate and thermal conductivity in gas wells. The proposed approach has been applied to determine the well gas rate and formation thermal conductivity from the acquired well pressure and temperature data in field A. It allows for recommending well stimulation of layers with low production rates.

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