Sensitivity study of SMILES-2 for chemical species

Manago, Naohiro; Ozeki, Hiroyuki; Ochiai, Satoshi; Baron, Philippe

doi:10.1117/12.2194832

Cited by 6 publications

(3 citation statements)

References 31 publications

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“…Because of the low abundance of BrO, measurements must be significantly averaged in order to get reliable results (Millán et al, 2012). CO and H 2 CO are the major species in the CH 4 oxidation to CO 2 and H 2 O in the stratosphere and mesosphere (Suzuki et al, 2015). The major spectral line of CO used by MLS is at 230.538 GHz, however, the 661.07 GHz line can also provide information (Livesey et al, 2008).…”

Section: Instrument Characteristicsmentioning

confidence: 99%

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

Wang¹,

Wang²,

Duan³

2019

Preprint

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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 O 3 , HCl, ClO, N 2 O, NO, NO 2 , HOCl, H 2 O, HNO 3 , HCN, CO, SO 2 , 10 BrO, HO 2 , H 2 CO, CH 3 Cl, CH 3 OH, and CH 3 CN 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 15 measurement are considered in simulation, respectively. Temperature profile can be obtained with the precision of < 2K for a single scan from 15 to 85 km by using 118 GHz radiometer, and the 240 and 643 GHz radiometer can provide temperature information in the upper troposphere. Chemical species such as H 2 O, O 3 , HCl, N 2 O, and HNO 3 show high single scan retrieval precision of 1-50% at most altitudes. The other species should be retrieved by using averaged measurements because of the weak intensity or low abundance. 20 IntroductionHigh precision observation of the Earth's atmosphere is essential to the numerical weather prediction and climate change studies. The satellite can provide global coverage atmospheric monitoring in a short time. Instruments such as nadir microwave sounder and infrared sounder have been applied to measure the atmospheric temperature and humidity but with the poor vertical resolution and altitude range (Swadley et al., 2008). Terahertz limb sounder can not only provide the 25 temperature profile with better vertical resolution but gather information on chemical composition in a wide altitude range and independent of the day-night cycle. Microwave limb sounding is a particularly useful technique in detecting stratospheric and mesospheric temperature and chemistry, and also has large potential for global wind measurement in the middle and upper atmosphere (Ochiai et al., 2017). Bands selectionThe spectral bands of TALIS are selected with the following criterions: (1) maximizing the number of species which will exert a strong influence on atmospheric chemistry and dynamics, (2) necessary space between the passband, (3) trade-off between realizable bandwidth and resolution. TALIS covers most spectral bands of EOS MLS and extends them. The broader bandwidth, finer resolution, and lower noise of TALIS can provide higher retrieval precision and effective altitude 15 range compared with EOS MLS. More chemical species can be measured by TALIS, such as NO 2 , NO, H 2 CO, and SO 2 (normal concentration).The 118 GHz radiometer, covering the strong O 2 line at 118.75 GH...

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Section: Instrument Characteristicsmentioning

confidence: 99%

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

Wang¹,

Wang²,

Duan³

2019

Preprint

View full text Add to dashboard Cite

show abstract

“…Satellites can provide daily global coverage of the atmosphere. Instruments such as nadir microwave sounders and infrared sounders have been applied to measure the atmospheric temperature and humidity but with the poor vertical resolution and altitude range (Swadley et al, 2008). Limb sounders can not only provide the temperature profile with better vertical resolution, but also gather information on chemical composition in a wide altitude range.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Duan

2020

Atmos. Meas. Tech.

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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.

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“…The new generation of earth atmosphere satellites proposed by NASA includes the scanning microwave limb sounder (SMLS), working in frequency bands of 240 and 643 GHz [21]. The superconducting submillimeter wave limb sounder 2 (SMILES-2) proposed by the Japan Aerospace Exploration Agency will scan the atmosphere from the low stratosphere to the low thermosphere to obtain a temperature profile of 15 to 160 km [22,23], with a system noise temperature from 120 to 990 K [1]. Stratospheric inferential wind (SIW) is a small submillimeter wave limb sounder developed in Sweden, which is mainly used to measure wind, temperature, and trace gases in the stratosphere.…”

Section: Introductionmentioning

confidence: 99%

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

Duan

Wang

et al. 2020

Sensors

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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.

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Sensitivity study of SMILES-2 for chemical species

Cited by 6 publications

References 31 publications

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

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

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

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

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