scholarly journals Variable anisotropy of small-scale stratospheric irregularities retrieved from stellar scintillation measurements by GOMOS/Envisat

2014 ◽  
Vol 7 (6) ◽  
pp. 1861-1872 ◽  
Author(s):  
V. Kan ◽  
V. F. Sofieva ◽  
F. Dalaudier
Keyword(s):  
Satellite Observations ◽  
Small Scale ◽  
Anisotropy Coefficient ◽  
Atmospheric Parameters ◽  
Air Density ◽  
Ozone Monitoring ◽  
D Model ◽  
Vertical Scales ◽  
Stellar Scintillation ◽  
Variable Anisotropy

Abstract. In this paper, we consider possibilities for studying the anisotropy of small-scale air density irregularities using satellite observations of bi-chromatic stellar scintillations during tangential occultations. Estimation of the anisotropy coefficient (the ratio of the characteristic horizontal to vertical scales) and other atmospheric parameters is based on the comparison of simulated/theoretical and experimental auto-spectra and coherency spectra of scintillation. Our analyses exploit a 3-D model of the spectrum of atmospheric inhomogeneities, which consists of anisotropic and isotropic components. For the anisotropic component, a spectral model with variable anisotropy is used. Using stellar scintillation measurements by GOMOS (Global Ozone Monitoring by Occultation of Stars) fast photometers, estimates of the anisotropy coefficient are obtained for atmospheric irregularities with vertical scales of 8–55 m at altitudes of 43–30 km. It is shown that the anisotropy increases from about 10 to 50 with increasing vertical scales.

scholarly journals Variable anisotropy of small-scale stratospheric irregularities retrieved from stellar scintillation measurements by GOMOS/Envisat

2014 ◽  
Vol 7 (2) ◽  
pp. 1275-1304
Author(s):  
V. Kan ◽  
V. F. Sofieva ◽  
F. Dalaudier
Keyword(s):  
Satellite Observations ◽  
Small Scale ◽  
Anisotropy Coefficient ◽  
Atmospheric Parameters ◽  
Air Density ◽  
Ozone Monitoring ◽  
D Model ◽  
Vertical Scales ◽  
Stellar Scintillation ◽  
Variable Anisotropy

Abstract. In this paper, we consider possibilities for studying the anisotropy of small-scale air density irregularities using satellite observations of bi-chromatic stellar scintillations during tangential occultations. Estimation of the anisotropy coefficient (the ratio of the characteristic horizontal to vertical scales) and other atmospheric parameters is based on the comparison of simulated/theoretical and experimental auto-spectra and coherency spectra of scintillation. Our analyses exploit a 3-D model of the spectrum of atmospheric inhomogeneities, which consists of anisotropic and isotropic components. For the anisotropic component, a spectral model with variable anisotropy is used. Using stellar scintillation measurements by GOMOS (Global Ozone Monitoring by Occultation of Stars) fast photometers, estimates of the anisotropy coefficient are obtained for atmospheric irregularities with vertical scales of 8–55 m at altitudes of 43–30 km. It is shown that the anisotropy increases from about 10 to 50 with increasing vertical scales.

scholarly journals Anisotropy of small-scale stratospheric irregularities retrieved from scintillations of a double star α-Cru observed by GOMOS/ENVISAT

2012 ◽  
Vol 5 (4) ◽  
pp. 4881-4904
Author(s):  
V. Kan ◽  
V. F. Sofieva ◽  
F. Dalaudier
Keyword(s):  
Double Star ◽  
Satellite Observations ◽  
Spectral Model ◽  
Small Scale ◽  
Anisotropy Coefficient ◽  
Air Density ◽  
Ozone Monitoring ◽  
Vertical Scales

Abstract. In this paper, we discuss estimating anisotropy of air density irregularities (ratio of characteristic horizontal and vertical scales) from satellite observations of bi-chromatic scintillations of a double star whose components are not resolved by the detector. The analysis is based on fitting experimental auto- and cross-spectra of scintillations by those computed using the 3-D spectral model of atmospheric irregularities consisting of anisotropic and isotropic components. Application of the developed method to the scintillation measurements of the double star α-Cru by GOMOS (Global Ozone Monitoring by Occultation of Stars) fast photometers results in estimates of anisotropy coefficient of ~15–20 at altitudes 30–38 km, as well as other parameters of atmospheric irregularities. The obtained estimates of the anisotropy coefficient correspond to small-scale irregularities, close to the buoyancy scale.

scholarly journals Anisotropy of small-scale stratospheric irregularities retrieved from scintillations of a double star α-Cru observed by GOMOS/ENVISAT

2012 ◽  
Vol 5 (11) ◽  
pp. 2713-2722 ◽  
Author(s):  
V. Kan ◽  
V. F. Sofieva ◽  
F. Dalaudier
Keyword(s):  
Double Star ◽  
Satellite Observations ◽  
Spectral Model ◽  
Small Scale ◽  
Anisotropy Coefficient ◽  
Air Density ◽  
Ozone Monitoring ◽  
Vertical Scales

Abstract. In this paper, we discuss estimating anisotropy of air density irregularities (ratio of characteristic horizontal and vertical scales) from satellite observations of bi-chromatic scintillations of a double star whose components are not resolved by the detector. The analysis is based on fitting experimental auto- and cross-spectra of scintillations by those computed using the 3-D spectral model of atmospheric irregularities consisting of anisotropic and isotropic components. Application of the developed method to the scintillation measurements of the double star α-Cru by GOMOS (Global Ozone Monitoring by Occultation of Stars) fast photometers results in estimates of anisotropy coefficient of ~15–20 at altitudes 30–38 km, as well as other parameters of atmospheric irregularities. The obtained estimates of the anisotropy coefficient correspond to small-scale irregularities, close to the buoyancy scale.

Internal Wave Generation by a Combination of Tidal and Steady Currents

2021 ◽  
Author(s):  
Xiaolin Bai ◽  
Kevin Lamb ◽  
José da Silva
Keyword(s):  
Internal Wave ◽  
Wave Generation ◽  
Satellite Observations ◽  
Internal Tides ◽  
Small Scale ◽  
Western Boundary ◽  
Boundary Current ◽  
Reanalysis Dataset ◽  
Amazon Shelf ◽  
Internal Wave Generation

<p>In the presence of topography, two main contributors for internal wave energy are tide-topography interaction transferring energy from the barotropic tide to internal tides, and lee wave generation when geostrophic currents or eddying abyssal flows interact with topography. In the past few decades, many studies considered the respective contribution of the oscillating flows or steady background flows, but few investigations have considered both.  </p><p>In this talk, we consider the joint effects of tidal and steady currents to investigate internal wave generation and propagation on the Amazon shelf, a hotspot for internal solitary wave (ISW) generation. The Amazon Shelf is off the mouth of the Amazon River in the southwest tropical Atlantic Ocean, affected by strong tidal constituents over complex bottom bathymetry and a strong western boundary current, the North Brazilian Current (NBC). Both satellite observations and numerical modelling are used in this study. Satellite observations provide a clear visualization of the wave characteristics, such as temporal and spatial distributions, propagating direction and its relation to background currents. Based on parameters from satellite observations and reanalysis dataset, we set up a model to numerically investigate the dynamics of the ISW generation. We demonstrate that the small-scale topography contributes to a rich generation of along-shelf propagating ISW, which significantly contribute to the ocean mixing and potentially cause sediment resuspension. Moreover, the ISW-induced currents also contribute to the sea surface wave breaking as observed by satellite measurements. In addition, statistics based on a decade of satellite images and numerical investigations on seasonal variations of the ISWs and the NBC improve our understanding of the generation and evolution of these nonlinear internal waves in the presence of background currents.</p>

1-D Model Analysis of Tesla Turbine for Small Scale Organic Rankine Cycle (ORC) System

2017 ◽  
Author(s):  
Jian Song ◽  
Chun-wei Gu
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
D Model

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

scholarly journals Estimating European volatile organic compound emissions using satellite observations of formaldehyde from the Ozone Monitoring Instrument

2010 ◽  
Vol 10 (23) ◽  
pp. 11501-11517 ◽  
Author(s):  
G. Curci ◽  
P. I. Palmer ◽  
T. P. Kurosu ◽  
K. Chance ◽  
G. Visconti
Keyword(s):  
Satellite Observations ◽  
Atmospheric Composition ◽  
Ozone Monitoring Instrument ◽  
Top Down ◽  
Bottom Up ◽  
Voc Emissions ◽  
The Balkans ◽  
Monitoring Instrument ◽  
Volatile Organic ◽  
Ozone Monitoring

Abstract. Emission of non-methane Volatile Organic Compounds (VOCs) to the atmosphere stems from biogenic and human activities, and their estimation is difficult because of the many and not fully understood processes involved. In order to narrow down the uncertainty related to VOC emissions, which negatively reflects on our ability to simulate the atmospheric composition, we exploit satellite observations of formaldehyde (HCHO), an ubiquitous oxidation product of most VOCs, focusing on Europe. HCHO column observations from the Ozone Monitoring Instrument (OMI) reveal a marked seasonal cycle with a summer maximum and winter minimum. In summer, the oxidation of methane and other long-lived VOCs supply a slowly varying background HCHO column, while HCHO variability is dominated by most reactive VOC, primarily biogenic isoprene followed in importance by biogenic terpenes and anthropogenic VOCs. The chemistry-transport model CHIMERE qualitatively reproduces the temporal and spatial features of the observed HCHO column, but display regional biases which are attributed mainly to incorrect biogenic VOC emissions, calculated with the Model of Emissions of Gases and Aerosol from Nature (MEGAN) algorithm. These "bottom-up" or a-priori emissions are corrected through a Bayesian inversion of the OMI HCHO observations. Resulting "top-down" or a-posteriori isoprene emissions are lower than "bottom-up" by 40% over the Balkans and by 20% over Southern Germany, and higher by 20% over Iberian Peninsula, Greece and Italy. We conclude that OMI satellite observations of HCHO can provide a quantitative "top-down" constraint on the European "bottom-up" VOC inventories.

scholarly journals Features of formation of small-scale wave disturbances during a sudden magnetospheric compression

2017 ◽  
Vol 3 (2) ◽  
pp. 34-42
Author(s):  
Алексей Моисеев ◽  
Aleksey Moiseev ◽  
Дмитрий Баишев ◽  
Dmitry Baishev ◽  
Владимир Мишин ◽  
...  
Keyword(s):  
Wave Front ◽  
Geomagnetic Field ◽  
Compression Wave ◽  
Interplanetary Medium ◽  
Interplanetary Shock ◽  
Satellite Observations ◽  
Small Scale ◽  
Plasma Parameters ◽  
Wave Disturbances ◽  
Periodic Changes

Quasi-periodic changes of the geomagnetic field and plasma parameters in the range of Pc 5 pulsations, which occurred immediately after the interaction of interplanetary shock (IPS) with Earth’s magnetosphere in the event of April 24, 2009 at 00:53 UT are examined using ground and satellite observations. The pulsations were localized at latitudes 66–74° in the noon (11 MLT) and evening (20 MLT) sectors. The analysis of hodographs of the geomagnetic field changes both from satellite and ground observations has shown the presence of vortical disturbances. In this event, both the IPS front in the interplanetary medium and the compression wave front in the magnetosphere had a slope in the ZGSM=0 plane; the inclination angle was 14° in the interplanetary medium and 34° in the magnetosphere.

scholarly journals PENGEMBANGAN MODEL PENILAIAN KOMPREHENSIF BERBASIS PROYEK PENDIDIKAN KEWIRAUSAHAAN TERINTEGRASI DI SMK

2013 ◽  
Vol 16 (2) ◽  
pp. 474-491
Author(s):  
Endang Mulyani
Keyword(s):  
Factor Analysis ◽  
Confirmatory Factor Analysis ◽  
Entrepreneurship Education ◽  
Comprehensive Assessment ◽  
Assessment Model ◽  
Small Scale ◽  
Education Project ◽  
Model Based ◽  
Confirmatory Factor ◽  
D Model

Tujuan penelitian ini adalah mengembangkan model penilaian kom-prehensif berbasis proyek pendidikan kewirausahaan terintegrasi di SMK. Pengembangan model penilaian ini menggunakan Four-D model meliputi ta-hap define, design, develop, dan disseminate. Rancangan model dalam penelitian ini belum sampai pada tahap disseminate, sehingga hanya meliputi tiga tahap-an yaitu tahap define, design, dan develop.Subjek penelitian adalah siswa kelas XI program studi penjualan, guru  ekonomi, dan guru kewirausahaan. Tek-nik pengumpulan data yang digunakan adalah angket, observasi, dokumen-tasi, dan tes. Teknik analisis data yang digunakan adalah teknik analisis dis-kriptif,dan Confirmatory Factor Analysis (CFA). Hasil penelitian adalah seba-gai berikut: 1) dilihat dari hasil analisis penilaian pakar menunjukan bahwa model penilaian secara umum termasuk dalam kategori baik dan dapat digunakan; 2) dilihat dari hasil analisis CFA, menunjukkan adanya  konsis-tensi, hal ini terbukti dari hasil pengujian model pada uji coba terbatas dan skala luas sama-sama menghasilkan model fit pada taraf signifikansi 5%. Kata kunci: model, penilaian, komprehensif, proyek, pendidikan kewirausahaan ______________________________________________________________ DEVELOPING A COMPREHENSIVE ASSESSMENT MODEL BASED ON AN INTREGATED ENTREPRENEURSHIP EDUCATION PROJECT IN VOCATIONAL SECONDARY SCHOOLSAbstract The main objective of this study is to develop a comprehensive assessment model based on an integrated entrepreneurship education project in vocational secondary schools. This developed assessment model employed the Four-D model, consisting of define, design, develop, and disseminate stages. The model in this study did not take the disseminate stage; it only took three stages, namely the define, design, and develop stages.The research subjects comprised Year XI students of the Sales Study Program, economics teachers, and entrepreneurship teachers.The data were collected through questionnaires, observations, documents, and tests. The data were analyzed using the descriptive analysis technique, and Confirmatory Factor Analysis (CFA). The research findings are as follows 1) based on the results of the analysis of the evaluation by experts, the assessment model in general is in the good category and is applicable; 2) based on the results of the analysis using CFA, there is a consistency, indicated by the model testing in the small-scale and large-scale tryouts revealing that the model fits the empirical data; besides, all constructs designed to measure variables are significant at alpha 5%.Keywords: model, assessment, comprehensive, project, entrepreneurship education

scholarly journals EVALUASI PROGRAM PENDIDIKAN DAN PELATIHAN MENGGUNAKAN APLIKASI BERBASIS ANDROID DI ARSIP NASIONAL REPUBLIK INDONESIA (ANRI)

2020 ◽  
Vol 8 (2) ◽  
pp. 89-94
Author(s):  
Vicihayu Dyah Mulyaningrum ◽  
Sumardi . ◽  
Eka Suhardi
Keyword(s):  
Large Scale ◽  
Development Program ◽  
Education And Training ◽  
Small Scale ◽  
Archival Education ◽  
National Archives ◽  
The Republic ◽  
Further Development ◽  
D Model ◽  
And Training

EVALUATION OF EDUCATION AND TRAINING PROGRAMS USING ANDROID-BASED APPLICATIONS IN THE NATIONAL ARCHIVES OF THE REPUBLIC OF INDONESIAThis study is intended to find out of how to develop Evaluation Development Program for Archival Education and Training Based on Android System. This research was conducted on the Nation Archive of Republic Indonesia. The research method used in this research was R & D and the instrument of the study was a questionnaire distributed to participants in archival education and training. The results showed that in developing program following the 3-D model. The 3-D model consists of 3 stages: define, design and develop. In the first stage (defining), it was found that the evaluation carried out was still utilizing paper media. It did not support the implementation of e-Government systems. The second step (design) was started from making the design, and continued with validating the product to the  team experts. The third step was development. This last stage was carried out by a small scale of trial which was participated with 47 participants. In the small-scale of trial phase was to detect the shortcomings of the product development and further development products would be fixed and be ready for large-scale trials. The large-scale of trial was attended by 95 participants. The analyzing result of the large scale trial had shown that the development product was valid and ready to be disseminated.

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