scholarly journals Statistical characteristics of AGW wave packet propagation in the lower atmosphere observed by the MU radar

2009 ◽  
Vol 27 (10) ◽  
pp. 3737-3753 ◽  
Author(s):  
F. S. Kuo ◽  
H. Y. Lue ◽  
C. L. Fern ◽  
J. Röttger ◽  
S. Fukao ◽  
...  
Keyword(s):  
Wave Packet ◽  
Group Velocity ◽  
Wave Period ◽  
Lower Atmosphere ◽  
Statistical Characteristics ◽  
Data Set ◽  
Horizontal Structure ◽  
North West ◽  
Mu Radar ◽  
Upward Moving

Abstract. We study the horizontal structure of the atmospheric gravity waves (AGW) in the height ranges between 6 and 22 km observed using the MU radar at Shigaraki in Japan, during a 3 day period in January and a 4 day period in August 1988. The data were divided by double Fourier transformation into a data set of upward moving waves and a data set of downward moving waves for independent analysis. The phase and group velocity tracing technique was applied to measure the vertical group and phase velocity as well as the characteristic period of the gravity wave packet. Then the dispersion equation of the linear theory of AGW was solved to obtain its intrinsic wave period – horizontal wavelength and horizontal group velocity – and the vertical flux of horizontal momentum associated with each wave packet was estimated to help determine the direction of the characteristic horizontal wave vector. The results showed that the waves with periods in the range of 30 min~6 h had horizontal scales ranging from 20 km to 1500 km, vertical scales from 4 km to 15 km, and horizontal phase velocities from 15 m/s to 60 m/s. The upward moving wave packets of wave period of 2 h~6 h had horizontal group velocities mainly toward east-south-east and northeast in winter, and mainly in the section between the directions of west-north-west and north in summer.

scholarly journals Studies of gravity wave propagation in the mesosphere observed by MU radar

2013 ◽  
Vol 31 (5) ◽  
pp. 845-858 ◽  
Author(s):  
H. Y. Lue ◽  
F. S. Kuo ◽  
S. Fukao ◽  
T. Nakamura
Keyword(s):  
Wave Packet ◽  
Phase Velocity ◽  
Group Velocity ◽  
Gravity Waves ◽  
Wave Packets ◽  
Wave Period ◽  
Parameter Analysis ◽  
Mu Radar ◽  
Horizontal Wavelength ◽  
Group Velocities

Abstract. Mesospheric data were analyzed by a composite method combining phase and group velocity tracing technique and the spectra method of Stokes parameter analysis to obtain the propagation parameters of atmospheric gravity waves (AGW) in the height ranges between 63.6 and 99.3 km, observed using the MU radar at Shigaraki in Japan in the months of November and July in the years 1986, 1988 and 1989. The data of waves with downward phase velocity and the data of waves with upward phase velocity were independently treated. First, the vertical phase velocity and vertical group velocity as well as the characteristic wave period for each wave packet were obtained by phase and group velocity tracing technique. Then its horizontal wavelength, intrinsic wave period and horizontal group velocity were obtained by the dispersion relation. The intrinsic frequency and azimuth of wave vector of each wave packet were checked by Stokes parameters analysis. The results showed that the waves with intrinsic periods in the range 30 min–4.5 h had horizontal wavelength ranging from 25 to 240 km, vertical wavelength from 2.5 to 12 km, and horizontal group velocities from 15 to 60 m s−1. Both upward moving wave packets and downward moving wave packets had horizontal group velocities mostly directed in the sector between directions NNE (north-north-east) and SEE in the month of November, and mostly in the sector between directions NW and SWS in the month of July. Comparing with mean wind directions, the gravity waves appeared to be more likely to propagate along with mean wind than against it. This apparent prevalence for downstream wave packets was found to be caused by a systematic filtering effect existing in the process of phase and group velocity tracing analysis: A significant portion of upstream wave packets might have been Doppler shifted out of the vertical range in phase and group velocity tracing analysis.

scholarly journals Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

2007 ◽  
Vol 25 (1) ◽  
pp. 77-86 ◽  
Author(s):  
F. S. Kuo ◽  
H. Y. Lue ◽  
C. L. Fern
Keyword(s):  
Wave Packet ◽  
Group Velocity ◽  
Gravity Waves ◽  
Theoretical Calculations ◽  
Wave Packets ◽  
Wave Length ◽  
Wave Period ◽  
Horizontal Distance ◽  
Characteristic Wave ◽  
Horizontal Wave

Abstract. The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr), with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.

High resolution turbulence observations in the middle and lower atmosphere by the MU radar with fast beam steerability: preliminary results

1986 ◽  
Vol 48 (11-12) ◽  
pp. 1269-1278 ◽  
Author(s):  
Shoichiro Fukao ◽  
Toru Sato ◽  
Toshitaka Tsuda ◽  
Mamoru Yamamoto ◽  
Susumu Kato
Keyword(s):  
High Resolution ◽  
Lower Atmosphere ◽  
Preliminary Results ◽  
Mu Radar

Comparison of Bivariate Models of the Distribution of Significant Wave Height and Peak Wave Period

2007 ◽  
Author(s):  
Catarina S. Soares ◽  
C. Guedes Soares
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Bivariate Normal Distribution ◽  
Wave Period ◽  
Peak Period ◽  
Data Set ◽  
Significant Wave ◽  
The North ◽  
Bivariate Models ◽  
The North Sea

This paper presents the results of a comparison of the fit of three bivariate models to a set of 14 years of significant wave height and peak wave period data from the North Sea. One of the methods defines the joint distribution from a marginal distribution of significant wave height and a set of distributions of peak period conditional on significant wave height. Other method applies the Plackett model to the data and the third one applies the Box-Cox transformation to the data in order to make it approximately normal and then fits a bivariate normal distribution to the transformed data set. It is shown that all methods provide a good fit but each one have its own strengths and weaknesses, being the choice dependent on the data available and applications in mind.

scholarly journals Retrieval of carbon dioxide vertical profiles from solar occultation observations and associated error budgets for ACE-FTS and CASS-FTS

2014 ◽  
Vol 7 (7) ◽  
pp. 2243-2262 ◽  
Author(s):  
C. E. Sioris ◽  
C. D. Boone ◽  
R. Nassar ◽  
K. J. Sutton ◽  
I. E. Gordon ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Chemistry ◽  
Time Frame ◽  
Lower Atmosphere ◽  
Data Set ◽  
Height Determination ◽  
Solar Occultation ◽  
Vertical Range ◽  
Main Challenge ◽  
Main Instrument

Abstract. An algorithm is developed to retrieve the vertical profile of carbon dioxide in the 5 to 25 km altitude range using mid-infrared solar occultation spectra from the main instrument of the ACE (Atmospheric Chemistry Experiment) mission, namely the Fourier transform spectrometer (FTS). The main challenge is to find an atmospheric phenomenon which can be used for accurate tangent height determination in the lower atmosphere, where the tangent heights (THs) calculated from geometric and timing information are not of sufficient accuracy. Error budgets for the retrieval of CO2 from ACE-FTS and the FTS on a potential follow-on mission named CASS (Chemical and Aerosol Sounding Satellite) are calculated and contrasted. Retrieved THs have typical biases of 60 m relative to those retrieved using the ACE version 3.x software after revisiting the temperature dependence of the N2 CIA (collision-induced absorption) laboratory measurements and accounting for sulfate aerosol extinction. After correcting for the known residual high bias of ACE version 3.x THs expected from CO2 spectroscopic/isotopic inconsistencies, the remaining bias for tangent heights determined with the N2 CIA is −20 m. CO2 in the 5–13 km range in the 2009–2011 time frame is validated against aircraft measurements from CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container), CONTRAIL (Comprehensive Observation Network for Trace gases by Airline), and HIPPO (HIAPER Pole-to-Pole Observations), yielding typical biases of −1.7 ppm in the 5–13 km range. The standard error of these biases in this vertical range is 0.4 ppm. The multi-year ACE-FTS data set is valuable in determining the seasonal variation of the latitudinal gradient which arises from the strong seasonal cycle in the Northern Hemisphere troposphere. The annual growth of CO2 in this time frame is determined to be 2.6 ± 0.4 ppm year−1, in agreement with the currently accepted global growth rate based on ground-based measurements.

Active Fault Systems in the inner North West Apennines: an updated view

2021 ◽  
Author(s):  
Giancarlo Molli ◽  
Rick Bennett ◽  
Jacques Malavieille ◽  
Enrico Serpelloni ◽  
Fabrizio Storti ◽  
...  
Keyword(s):  
Active Fault ◽  
Central Italy ◽  
Structural Features ◽  
Structural Studies ◽  
Data Set ◽  
Structural Domains ◽  
North West ◽  
Fault Systems ◽  
Internal Fault ◽  
Fault Characterization

<p>As part of an ongoing project of mapping, structural studies and fault characterization we present an updated tectonic scheme and data set for the active fault systems that shaped the inner portion of the Apennines north of the Arno river. Geomorphology, stratigraphy of Plio-Quaternary sediments, GPS data, historical and instrumental seismicity have been reviewed and combined with structural studies to define the neotectonic history of the investigated region. Within the studied area, first-order physiographic and structural features allow to define different structural domains related to a set of ranges with a dominant NW-SE direction separated by intramontane or continental/marine morphotectonic depressions of the Lunigiana, Garfagnana, Lucca-Mt.Albano, La Spezia-Carrara and the off-shore Viareggio basin. The main boundary faults and internal fault segments of the different structural domains were described while the Plio-Quaternary sedimentary records has been used to constrain their long to short term deformation and rates, with the aim to improve current Italian catalogues - DISS (INGV) and Ithaca (ISPRA) - with some utilities for the seismic microzonation local projects. Moreover, our work aims to draw the attention of the scientific community to the seismotectonics of a region in which the seismic hazard is largely considered medium to low despite the occurrence, one century ago, of one of the most destructive earthquakes that have struck the Italian peninsula, the 1920 Fivizzano EQ, with an estimated Mw 6.5 similar to the main shock of the 2016 Central Italy seismic sequence.</p><p> </p>

AGW manifestations in the Earth neutral atmosphere and ionosphere

2021 ◽  
Author(s):  
Tatiana Syrenova ◽  
Alexander Beletsky
Keyword(s):  
Optical System ◽  
Deep Convection ◽  
Lower Atmosphere ◽  
Automatic Identification ◽  
Complex Data ◽  
Neutral Atmosphere ◽  
Data Set ◽  
Acoustic Gravity Waves ◽  
Wave Disturbances ◽  
System Data

<p>Acoustic gravity waves (AGW) manifestations spread from the lower atmosphere to the upper layers due to processes such as orography, weather fronts, deep convection atmosphere, and vice versa, can form in the upper atmosphere during geomagnetic activity, receiving energy from the magnetosphere. These wave processes can be considered as a dynamic process that transfers energy between different atmospheric and latitudinal regions, therefore it is important to understand their basic parameters and behavior.</p><p>In this work, to study wave disturbances, we used the Keo Sentinel optical system data, designed to record the spatial pattern of the 630 nm emission intensity (emission height 180-300 km). The system is located at the Geophysical Observatory (GPO) of the ISTP SB RAS, near the Tory, Buryatiya, Russia (52<sup>0</sup> N, 103<sup>0</sup> E, height 670 m). The  interference filter transmission half-width is ~ 2 nm. Sight direction - zenith, field of view 145 degrees, exposure time 30-60 s (http://atmos.iszf.irk.ru/ru/data/keo).</p><p>For the analysis, we chose data obtained on clear, moonless nights from 2014 to March 2019. The total number of nights selected for analysis was 71 (~ 491 hours). An algorithm for the wave events and their characteristics automatic identification from the optic data was developed and tested. The approbation was carried out on a data set previously processed manually [Syrenova, Beletsky, 2019]. A comparison was made with traveling ionospheric disturbances (TID) characteristics obtained from the ISTP SB RAS radio-physical complex data [Medvedev et al., 2012].</p><p>The main directions of wave disturbances propagation obtained with automatic optical system data processing - southward (~ 175º) and eastward (~ 90º) - are similar to the TID directions. From the radiophysical complex data, the TID distribution from North to South prevails, the most probable azimuth is ~ 135º during the day, and ~ 205º at night. The most probable values ​​of the wave disturbances propagation velocity obtained as a result of automatic processing are about 80 m/s. These values ​​also accept well with the TID values.</p><p>The main characteristics obtained using the data of the optical and radiophysical complexes agree with each other. Differences in the preferred propagation direction of the recorded wave structures from the KEO Sentinel data from the directions obtained with photometers at the same observation point [Tashchilin, 2010, Podlesny, 2018], probably, associated with different observation heights.</p>

Short-Period Surface-Wave Tomography in the Continental United States—A Resource for Research

2021 ◽  
Author(s):  
Robert B. Herrmann ◽  
Charles J. Ammon ◽  
Harley M. Benz ◽  
Asiye Aziz-Zanjani ◽  
Joshua Boschelli
Keyword(s):  
United States ◽  
Group Velocity ◽  
Group Velocity Dispersion ◽  
Upper Crust ◽  
Data Set ◽  
Regional Patterns ◽  
Moment Tensors ◽  
Velocity Models ◽  
Short Period ◽  
Wave Tomography

Abstract The variation of phase and group velocity dispersion of Love and Rayleigh waves was determined for the continental United States and adjacent Canada. By processing ambient noise from the broadband channels of the Transportable Array (TA) of USArray and several Program for the Array Seismic Studies of the Continental Lithosphere experiments and using some earthquake recordings, the effort was focused on determining dispersion down to periods as short as 2 s. The relatively short distances between TA stations permitted the use of a 25  km×25  km grid for the four independent tomographic inversions (Love and Rayleigh and phase and group velocity). One reason for trying to obtain short-period dispersion was to have a data set capable of constraining upper crust velocity models for use in determining regional moment tensors. The benefit of focusing on short-period dispersion is apparent in the tomography maps—shallow geologic structures such as the Mid-Continent Rift, and the Michigan, Illinois, Anadarko, Arkoma, and Appalachian basins are imaged. In our processing, we noted that the phase velocities were more robustly determined than the group velocities. We also noted that the inability to obtain dispersion at short periods shows distinct regional patterns that may be related to the local upper crust structure.

Long-term variations of the oxygen red 630 nm line nightglow intensity

2007 ◽  
Vol 85 (2) ◽  
pp. 189-198 ◽  
Author(s):  
N B Gudadze ◽  
G G Didebulidze ◽  
G Sh. Javakhishvili ◽  
M G Shepherd ◽  
M V Vardosanidze
Keyword(s):  
Line Intensity ◽  
Peak Height ◽  
Mean Value ◽  
Lower Atmosphere ◽  
Data Set ◽  
Term Trend ◽  
Long Term Trend ◽  
Long Term Variations ◽  
Red Line

The long-term data set of total nightglow intensity of the oxygen red 630.0~nm line observed at Abastumani (41.8°N, 42.8°E) between 1957–1993 is investigated. The long-term trend and characteristic variations in solar radiation during an 11 year cycle of the red-line intensity are different after astronomical twilight (premidnight) and at midnight. The amplitude of deviation of the red-line intensity from its mean value at solar maximum and (or) minimum phase is greatest after astronomical twilight and decreases toward midnight. The long-term trend of these variations changes from its value about 0.74 R/year premidnight to its minimum negative value of about –1.92 R/year at and after midnight. This behavior of the long-term trend is considered as a possible result of an increase in electron density below the peak height (hmF2) of the ionospheric F2 layer and lowering of the height hmF2 after midnight predicted by the TIME-GCM model on the assumption of an increase in density of greenhouse gases in the lower atmosphere. The third-order regression equation (with different solar activity indices) is considered to be convenient for describing long-term variations in the mean annual red-line intensity.PACS Nos.: 94.10.Rk, 94.20.Ji, 92.60.Vb

scholarly journals Building a topological and geometrical model of poplar tree using portable on-ground scanning LIDAR

2008 ◽  
Vol 35 (10) ◽  
pp. 1080 ◽  
Author(s):  
Maurizio Teobaldelli ◽  
Alcoriza David Puig ◽  
Terenzio Zenone ◽  
Marco Matteucci ◽  
Günther Seufert ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Geometrical Model ◽  
Accurate Estimate ◽  
Horizontal Structure ◽  
Tree Structures ◽  
North West ◽  
Poplar Trees ◽  
Scanning Lidar ◽  
Architectural Characteristics ◽  
Poplar Tree

The objectives of this research were to investigate the suitability of advanced technologies like 3D-Laser scanning to acquire fair and sound information on structural and architectural characteristics of poplar stand, and to map topology of above-ground tree structures. The study area was an intensive poplar plantation located ~10 km north-west of the city of Pavia within the ‘Parco Regionale del Ticino’, Italy. A forest inventory of the poplar stand was conducted in 2005 and three 14-year-old poplar trees were selected and felled. The main architectural characteristics of poplar trees (destructive measurement) were compared with indirect measurement carried out using a portable on-ground scanning LIDAR IMAGER 5003 combined with the JRC-Reconstructor and AMAPmod softwares. The method permitted us to make an accurate estimate of the vertical and horizontal structure of the stand, to evaluate the stem and branches morphology of selected trees at different height in the canopy, and to create and validate multiscale representations of poplar tree architecture.

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