scholarly journals A Concept of 2U Spaceborne Multichannel Heterodyne Spectroradiometer for Greenhouse Gases Remote Sensing

2021 ◽  
Vol 13 (12) ◽  
pp. 2235
Author(s):  
Sergei Zenevich ◽  
Iskander Gazizov ◽  
Dmitry Churbanov ◽  
Yegor Plyashkov ◽  
Maxim Spiridonov ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Low Earth Orbit ◽  
High Spectral Resolution ◽  
Solar Occultation ◽  
Vertical Profiling ◽  
Multichannel Laser ◽  
Laser Heterodyne ◽  
One Year

We present the project of a 2U CubeSat format spaceborne multichannel laser heterodyne spectroradiometer (MLHS) for studies of the Earth’s atmosphere upper layers in the near-infrared (NIR) spectral range (1258, 1528, and 1640 nm). A spaceborne MLHS operating in the solar occultation mode onboard CubeSat platform, is capable of simultaneous vertical profiling of CO2, H2O, CH4, and O2, as well as Doppler wind measurements, in the tangent heights range of 5–50 km. We considered the low Earth orbit for the MLHS deployment and analyzed the expected surface coverage and spatial resolution during one year of operations. A ground-based prototype of the MLHS for CO2 and CH4 molecular absorption measurements with an ultra-high spectral resolution of 0.0013 cm−1 is presented along with the detailed description of its analytical characteristics and capabilities. Implementation of a multichannel configuration of the heterodyne receiver (four receivers per one spectral channel) provides a significant improvement of the signal-to-noise ratio with the reasonable exposure time typical for observations in the solar occultation mode. Finally, the capability of building up a tomographic picture of sounded gas concentration distributions provided by high spectral resolution is discussed.

Multichannel Heterodyne Spectroradiometer for Atmospheric Greenhouse Gas Measurements

2021 ◽  
Author(s):  
Sergei Zenevich ◽  
Iskander Gazizov ◽  
Dmitry Churbanov ◽  
Maxim Spiridonov ◽  
Alexander Rodin
Keyword(s):  
Spectral Resolution ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Basic Research ◽  
High Spectral Resolution ◽  
Vertical Profiles ◽  
Atmospheric Measurements ◽  
Stratospheric Wind ◽  
Signal Evaluation ◽  
Channel Configuration

<p>We present a portable, multichannel laser heterodyne spectroradiometer (MLHS) with a spectral resolution of 0.0013 cm-1 for precision column measurements and vertical profiling of atmospheric greenhouse gases (GHG). Sample spectra of CO<sub>2</sub> and CH<sub>4</sub> absorption lines obtained by direct Sun observations have allowed us to measure GHG column abundance with a precision of 0.5% for CO<sub>2</sub> and 10% for CH<sub>4</sub>, as well as to retrieve their vertical profiles and to get a vertical profile of the stratospheric wind Rodin et al. (2020). The fundamentals and specifics of the multichannel configuration implementation of heterodyne receivers are presented in Zenevich et al. (2020). This work presents the first data of atmospheric CO<sub>2</sub> and CH<sub>4</sub> measurements, which were taken in a 4-channel configuration of the heterodyne receiver. Such configuration has allowed us to get atmospheric spectra with the SNR 300-500 within 2 minutes period of signal integration and keep the high spectral resolution. The results of retrieving CO<sub>2</sub> and CH<sub>4</sub> vertical concentration profiles and vertical profiles of the stratospheric wind are also presented.</p><p> </p><p><strong>Acknowledgments</strong></p><p>This work has been supported by the Russian Foundation for Basic Research grants # 19-29-06104  (A.V. Rodin, M. V. Spiridonov, I.Sh. Gazizov) and # 19-32-90276 (S. G. Zenevich).</p><p> </p><p><strong>References:</strong></p><p>Zenevich S. et al.: The improvement of dark signal evaluation and signal-to-noise ratio of multichannel receivers in NIR heterodyne spectroscopy application for simultaneous CO2 and CH4 atmospheric measurements, OSA Continuum, 3, 7, 1801-1810, doi:10.1364/OSAC.395094, 2020.</p><p>Rodin, A. et al.: Vertical wind profiling from the troposphere to the lower mesosphere based on high-resolution heterodyne near-infrared spectroradiometry, Atmos. Meas. Tech., 13, 2299–2308, doi:10.5194/amt-13-2299-2020, 2020.</p>

Spectrum Filter Performance Analysis on Near-Infrared High-Spectral-Resolution Lidar

2016 ◽  
Vol 43 (4) ◽  
pp. 0414004
Author(s):  
张与鹏 Zhang Yupeng ◽  
刘东 Liu Dong ◽  
杨甬英 Yang Yongying ◽  
罗敬 Luo Jing ◽  
成中涛 Cheng Zhongtao ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Spectral Resolution ◽  
Near Infrared ◽  
High Spectral Resolution ◽  
Filter Performance ◽  
High Spectral Resolution Lidar

scholarly journals Global monitoring of terrestrial chlorophyll fluorescence from moderate spectral resolution near-infrared satellite measurements: methodology, simulations, and application to GOME-2

2013 ◽  
Vol 6 (2) ◽  
pp. 3883-3930 ◽  
Author(s):  
J. Joiner ◽  
L. Guanter ◽  
R. Lindstrot ◽  
M. Voigt ◽  
A. P. Vasilkov ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Spectral Resolution ◽  
Near Infrared ◽  
High Spectral Resolution ◽  
High Signal ◽  
Good Precision ◽  
Atmospheric Absorption ◽  
Red Fluorescence ◽  
Fluorescence Measurements ◽  
Global Mapping

Abstract. Globally mapped terrestrial chlorophyll fluorescence retrievals are of high interest because they can provide information on the functional status of vegetation including light-use efficiency and global primary productivity that can be used for global carbon cycle modeling and agricultural applications. In addition, fluorescence can contaminate photon path estimates from the O2 A-band that has become an integral part of missions to accurately measure greenhouse gas concentrations. Global mapping of far-red (~ 755–770 nm) terrestrial vegetation solar-induced fluorescence from space has been accomplished using the high spectral resolution (ν/Δ ν > 35 000) interferometer on the Japanese Greenhouse gases Observing SATellite (GOSAT). These satellite retrievals of fluorescence rely solely upon the filling-in of solar Fraunhofer lines that are not significantly affected by atmospheric absorption. Although these measurements provide near global coverage on a monthly basis, they suffer from relatively low precision and sparse spatial sampling. Here, we describe a new methodology to retrieve global far-red fluorescence information; we use hyperspectral data to disentangle the spectral signatures of three basic components in and surrounding the O2 A-band: atmospheric absorption, surface reflectance, and fluorescence radiance. Through detailed simulations, we demonstrate the feasibility of the approach and show that moderate spectral resolution measurements with a relatively high signal-to-noise ratio within and outside the O2 A-band can be used to retrieve far-red fluorescence information with good precision and accuracy. The method is then applied to data from the Global Ozone Monitoring Instrument 2 (GOME-2). The GOME-2 fluorescence retrievals display similar spatial structure as compared with GOSAT. GOME-2 enables global mapping of far-red fluorescence with higher precision over smaller spatial and temporal scales than is possible with GOSAT. It should be noted that both GOME-2 and GOSAT were designed to make atmospheric trace gas measurements and were not optimized for fluorescence measurements. Our approach can be applied to other existing and future space-based instruments that provide moderate spectral resolution observations in the near-infrared region.

scholarly journals Direct characterization of young giant exoplanets at high spectral resolution by coupling SPHERE and CRIRES+

2021 ◽  
Vol 646 ◽  
pp. A150
Author(s):  
G. P. P. L. Otten ◽  
A. Vigan ◽  
E. Muslimov ◽  
M. N’Diaye ◽  
E. Choquet ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Extrasolar Planets ◽  
Signal To Noise Ratio ◽  
Detection Limits ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
The Impact

Studies of atmospheres of directly imaged extrasolar planets with high-resolution spectrographs have shown that their characterization is predominantly limited by noise on the stellar halo at the location of the studied exoplanet. An instrumental combination of high-contrast imaging and high spectral resolution that suppresses this noise and resolves the spectral lines can therefore yield higher quality spectra. We study the performance of the proposed HiRISE fiber coupling between the direct imager SPHERE and the spectrograph CRIRES+ at the Very Large Telescope for spectral characterization of directly imaged planets. Using end-to-end simulations of HiRISE we determine the signal-to-noise ratio (S/N) of the detection of molecular species for known extrasolar planets in H and K bands, and compare them to CRIRES+. We investigate the ultimate detection limits of HiRISE as a function of stellar magnitude, and we quantify the impact of different coronagraphs and of the system transmission. We find that HiRISE largely outperforms CRIRES+ for companions around bright hosts like β Pictoris or 51 Eridani. For an H = 3.5 host, we observe a gain of a factor of up to 16 in observing time with HiRISE to reach the same S/N on a companion at 200 mas. More generally, HiRISE provides better performance than CRIRES+ in 2 h integration times between 50 and 350 mas for hosts with H < 8.5 and between 50 and 700 mas for H < 7. For fainter hosts like PDS 70 and HIP 65426, no significant improvements are observed. We find that using no coronagraph yields the best S/N when characterizing known exoplanets due to higher transmission and fiber-based starlight suppression. We demonstrate that the overall transmission of the system is in fact the main driver of performance. Finally, we show that HiRISE outperforms the best detection limits of SPHERE for bright stars, opening major possibilities for the characterization of future planetary companions detected by other techniques.

scholarly journals Smithsonian Astrophysical Observatory Ozone Mapping and Profiler Suite (SAO OMPS) formaldehyde retrieval

2015 ◽  
Vol 8 (9) ◽  
pp. 9209-9240 ◽  
Author(s):  
G. González Abad ◽  
A. Vasilkov ◽  
C. Seftor ◽  
X. Liu ◽  
K. Chance
Keyword(s):  
Detection Limit ◽  
Spectral Resolution ◽  
Signal To Noise Ratio ◽  
Data Sets ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
High Concentrations ◽  
One Year ◽  
The One

Abstract. This paper presents our new formaldehyde (H2CO) retrievals, obtained from spectra recorded by the nadir instrument of the Ozone Mapping and Profiler Suite (OMPS) flown on-board NASA's Suomi National Polar-orbiting Partnership (SUOMI-NPP) satellite. Our algorithm is similar to the one currently in place for the production of NASA's Ozone Monitoring Instrument (OMI) operational H2CO product. We are now able to produce a consistent set of long term data from two different instruments that share a similar concept. The ongoing overlap period between OMI and OMPS offers a perfect opportunity to study the consistency between both data sets. The different spatial and spectral resolution of the instruments is a source of discrepancy in the retrievals despite the similarity of the physic assumptions of the algorithm. We have concluded that the reduced spectral resolution of OMPS in comparison with OMI is not a significant obstacle in obtaining good quality retrievals. Indeed, the improved signal to noise ratio (SNR) of OMPS with respect to OMI helps to reduce the noise of the retrievals performed using OMPS spectra. However, the size of OMPS spatial pixels imposes a limitation in the capability to distinguish particular features of H2CO that are discernible with OMI. With root mean square (RMS) residuals ~ 5 × 10−4 for individual pixels we estimate the detection limit to be about 7.5 × 1015 molecules cm−2. Total vertical column densities (VCD) errors for individual pixels range between 40 % for pixels with high concentrations to 100 % or more for pixels with concentrations at or below the detection limit. We compare different OMI products with our OMPS product using one year of data, between September 2012 and September 2013. The seasonality of the retrieved slant columns is captured similarly by all products but there are discrepancies in the values of the VCDs. The mean biases among the two OMI products and our OMPS product are 21 % between OMI SAO and OMPS SAO and 38 % between OMI BIRA and OMPS SAO for eight selected regions.

scholarly journals Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

2011 ◽  
Vol 4 (3) ◽  
pp. 3097-3145
Author(s):  
S. A. McFarlane ◽  
K. L. Gaustad ◽  
E. J. Mlawer ◽  
C. N. Long ◽  
J. Delamere
Keyword(s):  
Great Plains ◽  
Spectral Resolution ◽  
Surface Albedo ◽  
Vegetation Index ◽  
Near Infrared ◽  
High Spectral Resolution ◽  
Surface Type ◽  
Southern Great Plains ◽  
Green Vegetation ◽  
Visible Wavelengths

Abstract. We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

scholarly journals Development of ZJU High-Spectral-Resolution Lidar for Aerosol and Cloud: Extinction Retrieval

2020 ◽  
Vol 12 (18) ◽  
pp. 3047
Author(s):  
Da Xiao ◽  
Nanchao Wang ◽  
Xue Shen ◽  
Eduardo Landulfo ◽  
Tianfen Zhong ◽  
...  
Keyword(s):  
Standard Method ◽  
Spectral Resolution ◽  
Extinction Coefficient ◽  
Signal To Noise Ratio ◽  
High Spectral Resolution ◽  
Aerosol Layer ◽  
Low Snr ◽  
Lidar Ratio ◽  
The Difference ◽  
High Spectral Resolution Lidar

The retrieval of the extinction coefficients of aerosols and clouds without assumptions is the most important advantage of the high-spectral-resolution lidar (HSRL). The standard method to retrieve the extinction coefficient from HSRL signals depends heavily on the signal-to-noise ratio (SNR). In this work, an iterative image reconstruction (IIR) method is proposed for the retrieval of the aerosol extinction coefficient based on HSRL data, this proposed method manages to minimize the difference between the reconstructed and raw signals based on reasonable estimates of the lidar ratio. To avoid the ill-posed solution, a regularization method is adopted to reconstruct the lidar signals in the IIR method. The results from Monte-Carlo (MC) simulations applying both standard and IIR methods are compared and these comparisons demonstrate that the extinction coefficient and the lidar ratio retrieved by the IIR method have smaller root mean square error (RMSE) and relative bias values than the standard method. A case study of measurements made by Zhejiang University (ZJU) HSRL is presented, and their results show that the IIR method not only obtains a finer structure of the aerosol layer under the condition of low SNR, but it is also able to retrieve more reasonable values of the lidar ratio.

scholarly journals A Monolithic Spatial Heterodyne Raman Spectrometer: Initial Tests

2020 ◽  
Vol 75 (1) ◽  
pp. 57-69
Author(s):  
Abigail Waldron ◽  
Ashley Allen ◽  
Arelis Colón ◽  
J. Chance Carter ◽  
S. Michael Angel
Keyword(s):  
Spectral Range ◽  
Spectral Resolution ◽  
Signal To Noise Ratio ◽  
Focal Length ◽  
High Spectral Resolution ◽  
Signal To Noise ◽  
Free Standing ◽  
Raman Spectrometer ◽  
Construction Techniques ◽  
The Stability

A monolithic spatial heterodyne Raman spectrometer (mSHRS) is described, where the optical components of the spectrometer are bonded to make a small, stable, one-piece structure. This builds on previous work, where we described bench top spatial heterodyne Raman spectrometers (SHRS), developed for planetary spacecraft and rovers. The SHRS is based on a fixed grating spatial heterodyne spectrometer (SHS) that offers high spectral resolution and high light throughput in a small footprint. The resolution of the SHS is not dependent on a slit, and high resolution can be realized without using long focal length dispersing optics since it is not a dispersive device. Thus, the SHS can be used as a component in a compact Raman spectrometer with high spectral resolution and a large spectral range using a standard 1024 element charge-coupled device. Since the resolution of the SHRS is not dependent on a long optical path, it is amenable to the use of monolithic construction techniques to make a compact and robust device. In this paper, we describe the use of two different monolithic SHSs (mSHSs), with Littrow wavelengths of 531.6 nm and 541.05 nm, each about 3.5 × 3.5 × 2.5 cm in size and weighing about 80 g, in a Raman spectrometer that provides ∼3500 cm−1 spectral range with 4–5 cm−1 and 8–9 cm−1 resolution, for 600 grooves/mm and 150 grooves/mm grating-based mSHS devices, respectively. In this proof of concept paper, the stability, spectral resolution, spectral range, and signal-to-noise ratio of the mSHRS spectrometers are compared to our bench top SHRS that uses free-standing optics, and signal to noise comparisons are also made to a Kaiser Holospec f/1.8 Raman spectrometer.

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