scholarly journals Study on the seasonal variation of Aeolus detection performance over China using ERA5 and radiosonde data

2021 ◽  
Author(s):  
Siying Chen ◽  
Rongzheng Cao ◽  
Yixuan Xie ◽  
Yinchao Zhang ◽  
Wangshu Tan ◽  
...  
Keyword(s):  
Relative Error ◽  
Wind Direction ◽  
Signal To Noise Ratio ◽  
Detection Performance ◽  
Radiosonde Data ◽  
Horizontal Wind ◽  
Horizontal Line ◽  
Weather Forecasts ◽  
L Band ◽  
Relative Errors

Abstract. Aeolus wind products have been available to ordinary users on May 12, 2020. In this paper, the Aeolus wind observations, L-band radiosonde (L-band RS) data and the European Centre for Medium-Range Weather Forecasts (ECMWF) fifth generation atmospheric reanalyses (ERA5) are used to analyse the seasonality of Aeolus detection performance over China. Based on the Rayleigh-clear data and Mie-cloudy data, the data quality of the Aeolus effective detection data is verified, and the results show that the Aeolus data is in good agreement with the L-band RS data and the ERA5 data. The relative errors of Aeolus data in the four regions (Chifeng, Baoshan, Shapingba and Qingyuan) in China were calculated according to different months (July to December 2019, May to October 2020). The relative error of the Rayleigh-clear data in summer is significantly higher than that in winter, as the mean relative error parameter in July is 174 % higher than that in December. Besides, the distribution about the wind direction and the high-altitude clouds in different months (July and December) are analysed. The results show that the distribution of angle, between the horizontal wind direction of the atmosphere and the horizontal line of sight (HLOS), has a greater proportion in the high error interval (70°–110°) in summer, and this proportion is 8.14 % higher in July than in December. In addition, the cloud top height in summer is about 3–5 km higher than in winter, which may reduce the signal-to-noise ratio (SNR) of Aeolus. The results show that the detection performance of Aeolus is affected by seasonal factors, which may be caused by seasonal changes in wind direction and cloud distribution.

scholarly journals Study of the seasonal variation in Aeolus wind product performance over China using ERA5 and radiosonde data

2021 ◽  
Vol 21 (15) ◽  
pp. 11489-11504
Author(s):  
Siying Chen ◽  
Rongzheng Cao ◽  
Yixuan Xie ◽  
Yinchao Zhang ◽  
Wangshu Tan ◽  
...  
Keyword(s):  
Relative Error ◽  
Wind Direction ◽  
Signal To Noise Ratio ◽  
Product Performance ◽  
Radiosonde Data ◽  
Horizontal Wind ◽  
Horizontal Line ◽  
The Mean ◽  
L Band ◽  
Relative Errors

Abstract. Aeolus wind products became available to the public on 12 May 2020. In this study, Aeolus wind observations, L-band radiosonde (RS) data, and the European Centre for Medium-Range Weather Forecasts fifth-generation atmospheric reanalysis (ERA5) data were used to analyze the seasonality of Aeolus wind product performance over China. Based on the Rayleigh-clear and Mie-cloudy data, the data quality of the Aeolus effective detection data was verified, and the results showed that the Aeolus data were in good agreement with the L-band RS and ERA5 data. The Aeolus data relative errors in the four regions (Chifeng, Baoshan, Shapingba, and Qingyuan) in China were calculated based on different months (July to December 2019 and May to October 2020). The relative error in the Rayleigh-clear data in summer was significantly higher than that in winter, with the mean relative error parameter in July 174 % higher than that in December. The mean random error increased by 0.97 m s−1 in July compared with December, which also supported this conclusion. In addition, the distribution of the wind direction and high-altitude clouds in different months (July and December) was analyzed. The results showed that the distribution of the angle between the horizontal wind direction of the atmosphere and the horizontal line of sight had a greater proportion in the high error interval (70–110∘) in summer, and this proportion was 8.14 % higher in July than in December. The cloud top height in summer was approximately 3–5 km higher than that in winter, which might decrease the signal-to-noise ratio of Aeolus. Therefore, the wind product performance of Aeolus was affected by seasonal factors, which might be caused by seasonal changes in wind direction and cloud distribution.

scholarly journals Middle-atmospheric zonal and meridional wind profiles from polar, tropical and midlatitudes with the ground-based microwave Doppler wind radiometer WIRA

2014 ◽  
Vol 7 (12) ◽  
pp. 4491-4505 ◽  
Author(s):  
R. Rüfenacht ◽  
A. Murk ◽  
N. Kämpfer ◽  
P. Eriksson ◽  
S. A. Buehler
Keyword(s):  
Zonal Wind ◽  
Signal To Noise Ratio ◽  
Optimal Estimation ◽  
Meridional Wind ◽  
Horizontal Wind ◽  
Data Series ◽  
Weather Forecasts ◽  
Average Wind ◽  
Set Up ◽  
Wind Profiles

Abstract. WIRA is a ground-based microwave Doppler spectroradiometer specifically designed for the measurement of profiles of horizontal wind in the upper stratosphere and lower mesosphere region where no other continuously running measurement technique exists. A proof of principle has been delivered in a previous publication. A technical upgrade including a new high-frequency amplifier and sideband filter has improved the signal to noise ratio by a factor of 2.4. Since this upgrade the full horizontal wind field comprising zonal and meridional wind profiles is continuously measured. A completely new retrieval based on optimal estimation has been set up. Its characteristics are detailed in the present paper. Since the start of the routine operation of the first prototype in September 2010, WIRA has been measuring at four different locations at polar, mid- and tropical latitudes (67°22' N/26°38' E, 46°57' N/7°26' E, 43°56' N/5°43' E and 21°04' S/55°23' E) for time periods between 5.5 and 11 months. The data presented in this paper are daily average wind profiles with typical uncertainties and resolutions of 10 to 20 m s−1 and 10 to 16 km, respectively. A comparison between the data series from WIRA and European Centre for Medium-Range Weather Forecasts (ECMWF) model data revealed agreement within 10% in the stratospheric zonal wind. The meridional wind profiles agree within their error bars over the entire sensitive altitude range of WIRA. However, significant differences in the mesospheric zonal wind speed of up to 50% have been found.

Application of pyrometer and standard sample to determine surface temperature of studied materials

2019 ◽  
pp. 9-13
Author(s):  
V.Ya. Mendeleyev ◽  
V.A. Petrov ◽  
A.V. Yashin ◽  
A.I. Vangonen ◽  
O.K. Taganov
Keyword(s):  
Composite Material ◽  
Surface Temperature ◽  
Relative Error ◽  
Wavelength Range ◽  
Standard Sample ◽  
A Priori ◽  
Temperature Changes ◽  
Surface Temperatures ◽  
Relative Errors ◽  
Normal Emissivity

Determining the surface temperature of materials with unknown emissivity is studied. A method for determining the surface temperature using a standard sample of average spectral normal emissivity in the wavelength range of 1,65–1,80 μm and an industrially produced Metis M322 pyrometer operating in the same wavelength range. The surface temperature of studied samples of the composite material and platinum was determined experimentally from the temperature of a standard sample located on the studied surfaces. The relative error in determining the surface temperature of the studied materials, introduced by the proposed method, was calculated taking into account the temperatures of the platinum and the composite material, determined from the temperature of the standard sample located on the studied surfaces, and from the temperature of the studied surfaces in the absence of the standard sample. The relative errors thus obtained did not exceed 1,7 % for the composite material and 0,5% for the platinum at surface temperatures of about 973 K. It was also found that: the inaccuracy of a priori data on the emissivity of the standard sample in the range (–0,01; 0,01) relative to the average emissivity increases the relative error in determining the temperature of the composite material by 0,68 %, and the installation of a standard sample on the studied materials leads to temperature changes on the periphery of the surface not exceeding 0,47 % for composite material and 0,05 % for platinum.

scholarly journals A Novel Technique for Image Steganalysis Based on Separable Convolution and Adversarial Mechanism

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2742
Author(s):  
Yuwei Ge ◽  
Tao Zhang ◽  
Haihua Liang ◽  
Qingfeng Jiang ◽  
Dan Wang
Keyword(s):  
Signal To Noise Ratio ◽  
Detection Performance ◽  
Hidden Information ◽  
Adaptive Steganography ◽  
Image Steganalysis ◽  
Channel Correlation ◽  
Cyberspace Security ◽  
And Training ◽  
Training Efficiency ◽  
Good Detection

Image steganalysis is a technique for detecting the presence of hidden information in images, which has profound significance for maintaining cyberspace security. In recent years, various deep steganalysis networks have been proposed in academia, and have achieved good detection performance. Although convolutional neural networks (CNNs) can effectively extract the features describing the image content, the difficulty lies in extracting the subtle features that describe the existence of hidden information. Considering this concern, this paper introduces separable convolution and adversarial mechanism, and proposes a new network structure that effectively solves the problem. The separable convolution maximizes the residual information by utilizing its channel correlation. The adversarial mechanism makes the generator extract more content features to mislead the discriminator, thus separating more steganographic features. We conducted experiments on BOSSBase1.01 and BOWS2 to detect various adaptive steganography algorithms. The experimental results demonstrate that our method extracts the steganographic features effectively. The separable convolution increases the signal-to-noise ratio, maximizes the channel correlation of residuals, and improves efficiency. The adversarial mechanism can separate more steganographic features, effectively improving the performance. Compared with the traditional steganalysis methods based on deep learning, our method shows obvious improvements in both detection performance and training efficiency.

scholarly journals Tropopause and jetlet characteristics in relation to thunderstorm development over Cyprus

2010 ◽  
Vol 23 ◽  
pp. 113-117
Author(s):  
A. Orphanou ◽  
K. Nicolaides ◽  
D. Charalambous ◽  
P. Lingis ◽  
S. C. Michaelides
Keyword(s):  
Wind Direction ◽  
The Other ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Data Sets ◽  
Other Hand ◽  
The One

Abstract. In the present study, the monthly statistical characteristics of jetlet and tropopause in relation to the development of thunderstorms over Cyprus are examined. For the needs of the study the 12:00 UTC radiosonde data obtained from the Athalassa station (33.4° E, 35.1° N) for an 11-year period, from 1997 till 2007, were employed. On the basis of this dataset, the height and the temperature of the tropopause, as well as the height, wind direction and speed of the jetlet were estimated. Additionally, the days in the above period with observed thunderstorms were selected and the aforementioned characteristics of the jetlet and tropopause were noted. The two data sets were subsequently contrasted in an attempt to identify possible relations between thunderstorm development, on the one hand, and tropopause and jetlet characteristics, on the other hand.

scholarly journals On the Algorithms Used to Compute the Standard Deviation of Wind Direction

2009 ◽  
Vol 48 (10) ◽  
pp. 2144-2151 ◽  
Author(s):  
Pierre S. Farrugia ◽  
James L. Borg ◽  
Alfred Micallef
Keyword(s):  
Standard Deviation ◽  
Wind Direction ◽  
Atmospheric Stability ◽  
Angular Distance ◽  
Circular Statistics ◽  
Horizontal Wind ◽  
Stability Class ◽  
Mathematical Expressions ◽  
Analytical Work

Abstract The standard deviation of wind direction is a very important quantity in meteorology because in addition to being used to determine the dry deposition rate and the atmospheric stability class, it is also employed in the determination of the rate of horizontal diffusion, which in turn determines transport and dispersion of air pollutants. However, the computation of this quantity is rendered difficult by the fact that the horizontal wind direction is a circular variable having a discontinuity at 2π radians, beyond which the wind direction starts again from zero, thus preventing angular subtraction from being a straightforward procedure. In view of such a limitation, this work is meant to provide new mathematical expressions that simplify both the computational and analytical work involved in handling the standard deviation of wind direction. This is achieved by deriving a number of Fourier series and Taylor expansions that can represent the minimum angular distance and its powers. Using these expressions, the relation between two algorithms commonly used to determine the standard deviation of wind direction is analyzed. Furthermore, given that these trigonometric expansions effectively reduce the mathematical complexity involved when dealing with circular statistics, their potential application to solve other problems is discussed.

scholarly journals Adaptive Beamforming Technique for Accurate Vertical Wind Measurements with Multichannel MST Radar

2012 ◽  
Vol 29 (12) ◽  
pp. 1769-1775 ◽  
Author(s):  
Koji Nishimura ◽  
Takuji Nakamura ◽  
Toru Sato ◽  
Kaoru Sato
Keyword(s):  
Signal To Noise Ratio ◽  
Adaptive Beamforming ◽  
Vertical Wind ◽  
Constrained Minimization ◽  
Horizontal Wind ◽  
Signal To Noise ◽  
Mst Radar ◽  
Vertical Beam ◽  
Noise Ratio ◽  
Beamforming Technique

Abstract Aspect-sensitive backscattering of the atmosphere causes a small error in an effective line-of-sight direction in vertical beam observations leading to a serious degradation of vertical wind estimates due to contamination by horizontal wind components. An adaptive beamforming technique for a multichannel mesosphere–stratosphere–troposphere (MST) radar is presented, which makes it possible to measure the vertical wind velocity with higher accuracy by adaptively generating a countersteered reception beam against an off-vertically shifted echo pattern. The technique employs the norm-constrained direction-constrained minimization of power (NC-DCMP) algorithm, which provides not only robustness but also higher accuracy than the basic direction-constrained minimization of power algorithm in realistic conditions. Although the technique decreases the signal-to-noise ratio, the ratio is controlled and bound at a specified level by the norm constraint. In the case that a decrease of −3 dB is acceptable in a vertical beam observation, for which usually a much higher signal-to-noise ratio is obtained than for oblique beams, the maximum contamination is suppressed to even for the most imbalanced aspect sensitivity.

Determination of Xanthates, Dithiocarbamates, and Some Fungicides by Titration with Electrogenerated Iodine in Anhydrous Acetonitrile

1983 ◽  
Vol 66 (3) ◽  
pp. 646-650
Author(s):  
Dale D Clyde
Keyword(s):  
Dimethyl Sulfoxide ◽  
Cross Section ◽  
Relative Error ◽  
Potassium Iodide ◽  
Anhydrous Acetonitrile ◽  
Platinum Electrodes ◽  
Cell Compartment ◽  
End Point ◽  
Relative Errors

Abstract Xanthates, dithiocarbamates, and the fungicides maneb and zineb were determined by titration with electrogenerated iodine in anhydrous acetonitrile. The electrolyte was potassium iodide. The generating electrode was a platinum spiral (2.5 cm diameter, 2 mm cross section). The enclosed cell compartment was continuously flushed with dry nitrogen, and sample solutions (0.20-0.40 mL) were introduced by syringe. With the aid of 2 platinum electrodes, the end point was indicated amperometrically. Ten minutes was required for each determination. The compounds were determined at ≥5 μequiv. with relative errors of 0.21-9%. Precision is 0.60-5.7%. Thiourea, sulfur, and urea did not interfere, but thioacetamide did. Solutions of maneb and zineb in dimethyl sulfoxide are stable enough that μequiv. amounts of each compound can be determined with a relative error of 7% or less.

scholarly journals Vertical wavenumber spectra of three-dimensional winds revealed by radiosonde observations at midlatitude

2017 ◽  
Vol 35 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Shao Dong Zhang ◽  
Chun Ming Huang ◽  
Kai Ming Huang ◽  
Ye Hui Zhang ◽  
Yun Gong ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Meridional Wind ◽  
Vertical Wind ◽  
Radiosonde Data ◽  
Horizontal Wind ◽  
Spectral Structure ◽  
Wind Fluctuation ◽  
The Mean

Abstract. By applying 12-year (1998–2009) radiosonde data over a midlatitude station, we studied the vertical wavenumber spectra of three-dimensional wind fluctuations. The horizontal wind spectra in the lower stratosphere coincide well with the well-known universal spectra, with mean spectral slopes of −2.91 ± 0.09 and −2.99 ± 0.09 for the zonal and meridional wind spectra, respectively, while the mean slopes in the troposphere are −2.64 ± 0.07 and −2.70  ±  0.06, respectively, which are systematically less negative than the canonical slope of −3. In both the troposphere and lower stratosphere, the spectral amplitudes (slopes) of the horizontal wind spectra are larger (less negative) in winter, and they are larger (less negative) in the troposphere than in the lower stratosphere. Moreover, we present the first statistical results of vertical wind fluctuation spectra, which revealed a very shallow spectral structure, with mean slopes of −0.58 ± 0.06 and −0.23 ± 0.05 in the troposphere and lower stratosphere, respectively. Such a shallow vertical wind fluctuation spectrum is considerably robust. Different from the horizontal wind spectrum, the slopes of the vertical wind spectra in both the troposphere and lower stratosphere are less negative in summer. The height variation of vertical wind spectrum amplitude is also different from that of the horizontal wind spectrum, with a larger amplitude in the lower stratosphere. These evident differences between the horizontal and vertical wind spectra strongly suggest they should obey different spectral laws. Quantitative comparisons with various theoretical models show that no existing spectral theories can comprehensively explain the observed three-dimensional wind spectra, indicating that the spectral features of atmospheric fluctuations are far from fully understood.

Simultaneous determination of disopyramide and mono-N-dealkyldisopyramide enantiomers in plasma and urine by use of a chiral cellulose-derivative column

1990 ◽  
Vol 36 (7) ◽  
pp. 1300-1304 ◽  
Author(s):  
H Echizen ◽  
K Ochiai ◽  
Y Kato ◽  
K Chiba ◽  
T Ishizaki
Keyword(s):  
Simultaneous Determination ◽  
Active Metabolite ◽  
Signal To Noise Ratio ◽  
Plasma Concentrations ◽  
Internal Standard ◽  
Cellulose Derivative ◽  
Ultraviolet Detection ◽  
Lower Detection ◽  
Relative Errors

Abstract This assay allows simultaneous determination of the enantiomers of both disopyramide and its active metabolite, mono-N-dealkyldisopyramide, in 1 mL of plasma or 0.1 mL of urine within approximately 35 min by HPLC with a chiral cellulose-derivative column and ultraviolet detection. Recoveries for the analytes and the internal standard (racemic verapamil) with an extraction from alkalinized plasma or urine into diethyl ether were greater than 90%. Intra- and interassay CVs for disopyramide enantiomers were less than 5.5% at 2.5 mg/L in plasma and less than 6.5% at 25 mg/L in urine; for mono-N-dealkyldisopyramide enantiomers they were less than 6.3% and less than 8.9%, respectively. Intra- and interassay relative errors for determining these analytes in plasma and urine at 2.5 and 25 mg/L, respectively, ranged from -5.9% to +2.5%. The calibration curves for the respective analytes were linear (r = 0.995 or greater, P less than 0.01) from 0.025 to 5.0 mg/L in plasma and from 0.5 to 10 mg/L in urine. The lower detection limits (signal-to-noise ratio of 3) for S(+)-disopyramide and the other analytes were 0.010 and 0.025 mg/L, respectively. We evaluated clinical applicability of this method by determining steady-state plasma concentrations and urinary excretions of the respective analytes in a pediatric patient being treated with racemic disopyramide.

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