scholarly journals Simulation of the Spectrum Response for the THz Atmosphere Limb Sounder (TALIS)

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 498
Author(s):  
Yongqiang Duan ◽  
Zhenzhan Wang ◽  
Haowen Xu ◽  
Wenyu Wang
Keyword(s):  
Spectral Response ◽  
Microwave Radiometer ◽  
Chemical Species ◽  
Center Frequency ◽  
Integration Time ◽  
Science Center ◽  
National Space ◽  
Degradation Ratio ◽  
Scientific Goal ◽  
Academy Of Sciences

The THz atmospheric limb sounder (TALIS) is a microwave radiometer developed by the National Space Science Center of the Chinese Academy of Sciences for the detection of atmospheric trace gases. The observation range of the instrument mainly focuses on the middle and upper atmosphere (10–100 km above the earth’s surface). The detection targets include the temperature, pressure, and more than 10 kinds of atmospheric components. Its scientific goal is to improve our comprehension of atmospheric chemical composition and dynamics, and to monitor environmental pollution and sources in the atmosphere. The TALIS instrument is composed of an antenna, superheterodyne radiometers, and digital fast Fourier transform (FFT) spectrometers. By measuring the atmospheric thermal radiance in the wide frequency band with 118, 190, 240, and 643 GHz as the center frequency, the required volume mixing ratio (VMR) of atmospheric chemical species can be obtained. This paper introduces the characteristics of the TALIS instrument, and establishes a simulation model for the TALIS spectrometer. Through a joint simulation with an atmosphere radiative transfer simulator (ARTS), the TALIS instrument performance is evaluated from the aspects of calibration, the imbalance of two sidebands, the spectrum resolution, and quantization. The simulation results show that the two-point calibration can well-restore the radiance spectrum of the scene target and remove the influence of the spectral response function (SRF); the double side band (DSB) receiver with a 2 MHz resolution can meet the sensitivity and spectrum resolution requirements. Finally, the sensitivity errors of different quantization bits are given by the simulation and the results show that at 8-bit, the sensitivity and its degradation ratio are 1.251 K and 1.036 at a 2 MHz spectrum resolution and 100 ms integration time, respectively.

scholarly journals Performance Evaluation of THz Atmospheric Limb Sounder (TALIS) of China

2019 ◽  
Author(s):  
Wenyu Wang ◽  
Zhenzhan Wang ◽  
Yongqiang Duan
Keyword(s):  
Atmospheric Chemistry ◽  
Thermal Emission ◽  
Chemical Species ◽  
Vertical Resolution ◽  
Science Center ◽  
Theoretical Simulation ◽  
National Space ◽  
Chinese Academy Of Sciences ◽  
High Vertical Resolution ◽  
Academy Of Sciences

Abstract. THz Atmospheric Limb Sounder (TALIS) is a microwave limb sounder being developed for atmospheric high precision observation by the National Space Science Center, Chinese Academy of Sciences (NSSC, CAS). It is designed to measure the temperature and chemical species such as O3, HCl, ClO, N2O, NO, NO2, HOCl, H2O, HNO3, HCN, CO, SO2, BrO, HO2, H2CO, CH3Cl, CH3OH, and CH3CN with high vertical resolution from surface to about 100 km to improve our comprehension of atmospheric chemistry and dynamics, and to monitor the man-made pollution in the atmosphere. Four heterodyne radiometers including several FFT spectrometers of 2 GHz bandwidth with 2 MHz resolution are employed to obtain the atmospheric thermal emission in broad spectral regions centred near 118, 190, 240, and 643 GHz. A theoretical simulation is performed to estimate the retrieval precision of the main targets. Single scan measurement and averaged measurement are considered in simulation, respectively. Temperature profile can be obtained with the precision of

scholarly journals Performance evaluation of THz Atmospheric Limb Sounder (TALIS) of China

2020 ◽  
Vol 13 (1) ◽  
pp. 13-38 ◽  
Author(s):  
Wenyu Wang ◽  
Zhenzhan Wang ◽  
Yongqiang Duan
Keyword(s):  
Atmospheric Chemistry ◽  
Thermal Emission ◽  
Chemical Species ◽  
Science Center ◽  
Theoretical Simulation ◽  
National Space ◽  
Weak Intensity ◽  
Chinese Academy Of Sciences ◽  
High Vertical Resolution ◽  
Academy Of Sciences

Abstract. THz Atmospheric Limb Sounder (TALIS) is a microwave limb sounder being developed for atmospheric vertically resolved profile observations by the National Space Science Center, Chinese Academy of Sciences (NSSC, CAS). It is designed to measure temperature and chemical species such as O3, HCl, ClO, N2O, NO, NO2, HOCl, H2O, HNO3, HCN, CO, SO2, BrO, HO2, H2CO, CH3Cl, CH3OH, and CH3CN with a high vertical resolution from about 10 to 100 km to improve our comprehension of atmospheric chemistry and dynamics and to monitor the man-made pollution in the atmosphere. Four heterodyne radiometers including several FFT spectrometers of 2 GHz bandwidth with 2 MHz resolution are employed to obtain the atmospheric thermal emission in broad spectral regions centred near 118, 190, 240, and 643 GHz. A theoretical simulation is performed to estimate the retrieval precision of the main targets and to compare them with that of Aura MLS standard spectrometers. Single scan measurement and averaged measurement are considered in the simulation, respectively. The temperature profile can be obtained with a precision of <2 K for a single scan from 10 to 60 km by using the 118 GHz radiometer, and the 240 and 643 GHz radiometers can provide temperature information in the upper troposphere. Chemical species such as H2O, O3, and HCl show a relatively good single scan retrieval precision of <20 % over most of the useful range and ClO, N2O, and HNO3 can be retrieved with a precision of <50 %. The other species should be retrieved by using averaged measurements because of the weak intensity and/or low abundance.

scholarly journals Effect Analysis of the Digital Spectrometer FFT Algorithm on THz Atmospheric Limb Sounder (TALIS) System Sensitivity

2021 ◽  
Vol 13 (15) ◽  
pp. 2921
Author(s):  
Haowen Xu ◽  
Hao Lu ◽  
Zhenzhan Wang ◽  
Wenming He ◽  
Wenyu Wang
Keyword(s):  
Chemical Constituents ◽  
Microwave Radiometer ◽  
Mean Value ◽  
Integration Time ◽  
Science Center ◽  
Effect Analysis ◽  
System Sensitivity ◽  
Full Band ◽  
Digital Spectrometer ◽  
The Ideal

THz Atmospheric Limb Sounder (TALIS) is a microwave radiometer designed by the National Space Science Center of the Chinese Academy of Sciences (NSSC, CAS) for measuring the vertical distribution of temperature and chemical constituents in the middle and upper atmosphere. The digital spectrometer is an important part of TALIS’ back end, which mainly realizes the function of spectral analysis. The radix 16 real-time complex fast Fourier transform (FFT) algorithm used in the digital spectrometer was obtained by improving and combining the parallel processing and complex processing of the FFT algorithm. In this study, the digital spectrometer parameter selection is systematically presented, and the effect of the digital spectrometer FFT algorithm on the TALIS system sensitivity is analyzed based on the TALIS system simulation model we established in the previous stage of this research. The results show that the actual full-band sensitivity obtained after using the FFT algorithm is consistent with the ideal full-band sensitivity of TALIS for different integration time, spectral resolutions, and quantization bits. However, the results of the comparison of the actual sub-band sensitivity after using the FFT algorithm with the ideal sub-band sensitivity show that the deterioration of the sub-band sensitivity will be caused by the FFT algorithm. The mean value of the deterioration ratio was found to be approximately 18%, and the maximum value of the deterioration ratio was approximately 33%.

scholarly journals Continuous Detection of Diurnal Sodium Fluorescent Lidar over Beijing in China

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 118
Author(s):  
Lifang Du ◽  
Jihong Wang ◽  
Yong Yang ◽  
Yuchang Xun ◽  
Faquan Li ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Time Range ◽  
Science Center ◽  
National Space ◽  
Sodium Layer ◽  
Chinese Academy Of Sciences ◽  
Academy Of Sciences ◽  
Observation Period

Based on application of the atomic filter technology in a signal detection system of lidar, the diurnal observation of sodium lidar were obtained using the system at the National Space Science Center of the Chinese Academy of Sciences at Beijing Yanqing station (40.5° N, 116° E) in April 2014. During the lidar observation period, among the 103 cases of continuous daytime observations, the longest time was 181 h. In the case of a continuous observation period of 5 days (13–18 October 2014), the signal-to-noise ratio reached to 19:1 at 12:00–13:00 Local Time of the daytime, when the spatial and time resolutions were respectively set to 96 m of 167 s. The improvements resulted in the highest detection level of any existing diurnal lidars in China. Some interesting phenomena such as the sporadic sodium layer have also been observed during the daytime. The daytime capability extended the observing time range of the earlier systems that were limited to only nighttime observations. This innovation provides a useful method for the studies of diurnal tides, photochemistry, gravity waves, and correlative modeling studies.

Recoverability of Callisto gravity field influenced by orbiter mission characteristics

2021 ◽  
Author(s):  
William Desprats ◽  
Daniel Arnold ◽  
Michel Blanc ◽  
Adrian Jäggi ◽  
Mingtao Li ◽  
...  
Keyword(s):  
Gravity Field ◽  
Noise Model ◽  
Force Model ◽  
Tracking Data ◽  
Science Center ◽  
National Space ◽  
Beta Angle ◽  
Dynamical Parameters ◽  
Range Rate ◽  
Orbiter Mission

&lt;p&gt;The exploration of Callisto is part of the extensive interest in the icy moons characterization. Indeed, Callisto is the Galilean moon with the best-preserved records of the Jovian system formation. Led by the National Space Science Center (NSSC), Chinese Academy of Science (CAS), the planned Gan De mission aims to send an orbiter around Callisto in order to characterize its surface and interior. Potential orbit configurations are currently under study for the Gan De mission proposal.&lt;/p&gt;&lt;p&gt;As part of a global characterization of Callisto, its gravity field can be inferred using radio tracking data from an orbiter. Mission characteristics such as orbit type, Earth beta angle and solar elongation will have a direct influence on the recoverability of its gravity field parameters. In this study, we will analyse this influence from closed-loop simulations using the planetary extension of the Bernese GNSS Softwareai.&lt;/p&gt;&lt;p&gt;A number of reference orbits with different orbital characteristics will be selected for the Gan De mission and, using an extended force model, will be propagated from different starting dates and different initial Earth beta angles. Realistic Doppler tracking data (2-way X-band Doppler range rate) will be simulated as measurements from ground stations, with a dedicated noise model. These observations will then be used to reconstruct the orbit along with dynamical parameters. The focus of this presentation will be on the quality of the retrieved gravity field parameters and tidal Love number k2.&lt;/p&gt;

scholarly journals 10 MHz Thin-Film PZT-Based Flexible PMUT Array: Finite Element Design and Characterization

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4335
Author(s):  
Jeong Nyeon Kim ◽  
Tianning Liu ◽  
Thomas N. Jackson ◽  
Kyusun Choi ◽  
Susan Trolier-McKinstry ◽  
...  
Keyword(s):  
Finite Element ◽  
Lead Zirconate Titanate ◽  
Focal Length ◽  
Spectral Response ◽  
Guided Wave ◽  
Center Frequency ◽  
Depth Of Field ◽  
High Frequency Ultrasound ◽  
Pulse Echo ◽  
2D Array

Piezoelectric micromachined ultrasound transducers (PMUT) incorporating lead zirconate titanate PbZr0.52Ti0.48O3 (PZT) thin films were investigated for miniaturized high-frequency ultrasound systems. A recently developed process to remove a PMUT from an underlying silicon (Si) substrate has enabled curved arrays to be readily formed. This research aimed to improve the design of flexible PMUT arrays using PZFlex, a finite element method software package. A 10 MHz PMUT 2D array working in 3-1 mode was designed. A circular unit-cell was structured from the top, with concentric layers of platinum (Pt)/PZT/Pt/titanium (Ti) on a polyimide (PI) substrate. Pulse-echo and spectral response analyses predicted a center frequency of 10 MHz and bandwidth of 87% under water load and air backing. A 2D array, consisting of the 256 (16 × 16) unit-cells, was created and characterized in terms of pulse-echo and spectral responses, surface displacement profiles, crosstalk, and beam profiles. The 2D array showed: decreased bandwidth due to protracted oscillation decay and guided wave effects; mechanical focal length at 2.9 mm; 3.7 mm depth of field for -6 dB; and -55.6 dB crosstalk. Finite element-based virtual prototyping identified figures of merit—center frequency, bandwidth, depth of field, and crosstalk—that could be optimized to design robust, flexible PMUT arrays.

Performance and Spectral Response of Far-Infrared Pb1−xSnxTe(In) Photodetectors

1999 ◽  
Vol 607 ◽  
Author(s):  
I. Ivanchik ◽  
D. Khokilov ◽  
J. Pipher ◽  
N. Raines ◽  
D. Watson
Keyword(s):  
State Of The Art ◽  
Spectral Response ◽  
Far Infrared ◽  
Integration Time ◽  
First Time

AbstractDirect comparison of performance has been done for a Pb1−xSnxTe(In) photodetector, a Si(Sb) BIB structure and a state of the art Ge(Ga) photoconductor in the integration cavity. The PblSnTe(In) photodetector shows several orders of magnitude higher responsivity S, then the Si(Sb) BIB at the wavelength λ ∼ 14 µm. Persistent photoresponse with SI ∼ 103 A/W at 40 mV bias and 1 s integration time at the wavelengths of, λ = 90 and 116 µm has been observed for the first time for the Pb1−xSnxTe(In) photodetector. This value is by a factor of ∼ 100 higher than the respective parameters of the Ge(Ga) photoconductor in the same conditions.

scholarly journals Studies of Permafrost in the European Northeast of Russia in the First Half of the 20th Century

2020 ◽  
pp. 173-181
Author(s):  
Tatyana P. Filippova ◽  
◽  
Nina G. Lisevich ◽  
Keyword(s):  
20Th Century ◽  
Ussr Academy ◽  
The Arctic ◽  
Science Center ◽  
Russian Academy Of Sciences ◽  
Leading Role ◽  
Wide Range ◽  
History Of ◽  
Academy Of Sciences

On the basis of a wide range of sources, the research analyzes the history of the study of permafrost in the territory of the European Northeast of Russia in the first half of the 20th century. The documentary sources revealed in the Archive of the Russian Academy of Sciences (Moscow), the National Archive of the Komi Republic (Syktyvkar), the Scientific Archive of the Komi Science Center of the Ural Branch of the Russian Academy of Sciences (Syktyvkar), the Vorkuta Museum and Exhibition Center (Vorkuta) are introduced into the scientific use for the first time. The 1920s became the period of the birth of a new scientific direction – permafrostology. This science gave an impetus to the systematic study and development of the North and the Arctic. The beginning of systematic geocryologic studies was connected with the development of the European Northeast in the 1920s–1930s. It has been determined that the USSR Academy of Sciences played the leading role in carrying out these studies: it organized special scientific expeditions for studying the cryolithozone of this region. The main results of the studies and their motives interconnected with the government’s interests in the development of valuable northern mineral resources are shown. The results of the expeditions were conclusions about the possibility of constructing large industrial facilities in the regions of the explored reserves of natural raw material resources. Following scientists’ recommendation, the industrial development of the Pechora coal basin and the colonization of the polar region began. The climatic and natural features of the region demanded stationary scientific research in the field of design and construction. The Vorkuta Research Permafrost Station (VRPS) (1936–1958), created under the supervision of the USSR Academy of Sciences, began to carry out this research. Today, the history of this station’s activities is poorly studied. The article presents the main directions of VRPS research: engineering permafrostology and general issues of permafrost studies. The staff of the station were researchers of the Committee on Permafrost Studies of the USSR Academy of Sciences and scientists from among prisoners of GULAG. The role of the staff who made a great contribution to permafrost studies is shown. Under the leadership of the scientists of the station, on the basis of their techniques, large industrial structures of Vorkuta District and Vorkuta, among them the first railroad in the conditions of permafrost, were designed. The conclusion is drawn on the leading role of scientists of the USSR Academy of Sciences in carrying out studies of permafrost soil in the European Northeast in the first half of the 20th century which became the basis in the successful solution of construction problems in the Arctic territory.

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