scholarly journals The Ultraviolet Visible Hyperspectral Imaging Spectrometer (UVHIS), and high-resolution NO<sub>2</sub> mapping from its first airborne observation

2020 ◽  
Author(s):  
Liang Xi ◽  
Fuqi Si ◽  
Yu Jiang ◽  
Haijin Zhou ◽  
Kai Zhan ◽  
...  
Keyword(s):  
Hyperspectral Imaging ◽  
Optical Design ◽  
Optical Absorption Spectroscopy ◽  
Array Detector ◽  
Vertical Column ◽  
Imaging Spectrometer ◽  
Charge Coupled Device ◽  
Ccd Array ◽  
Airborne Imaging ◽  
A Charge

Abstract. We present a novel airborne imaging differential optical absorption spectroscopy (DOAS) instrument: Ultraviolet Visible Hyperspectral Imaging Spectrometer (UVHIS), which is developed for trace gas monitoring and pollution mapping. Within a broad spectral range from 200 to 500 nm, operated in three channels, the spectral resolution of UVHIS is better than 0.5 nm. The optical design of each channel comprises a fore-optics with a field of view (FOV) of 40°, an Offner imaging spectrometer, and a charge-coupled device (CCD) array detector of 1032 × 1072 pixels. A first demonstration flight using UVHIS was undertaken on 23 June 2018, above an approximate 600 km2 area in Feicheng, China, with a spatial resolution of about 25 × 22 m2. Measurements of nadir backscattered solar radiation of channel 3 are used to retrieve vertical column densities (VCDs) of NO2 with a mean fitting error of 2.6 × 1015 molec cm−2. The UVHIS instrument clearly detected several emission plumes transporting from south to north, with a peak value of 3 × 1016 molec cm−2 in the dominant one. UVHIS NO2 vertical columns are well correlated with ground-based mobile DOAS observations, with a correlation coefficient of 0.65 for all co-located measurements, and a slight underestimation for polluted observations. This study demonstrates the capability of UVHIS for NO2 local emission and transmission monitoring.

scholarly journals First high-resolution tropospheric NO<sub>2</sub> observations from the Ultraviolet Visible Hyperspectral Imaging Spectrometer (UVHIS)

2021 ◽  
Vol 14 (1) ◽  
pp. 435-454
Author(s):  
Liang Xi ◽  
Fuqi Si ◽  
Yu Jiang ◽  
Haijin Zhou ◽  
Kai Zhan ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Hyperspectral Imaging ◽  
Total Error ◽  
Optical Design ◽  
Optical Absorption Spectroscopy ◽  
Array Detector ◽  
Vertical Column ◽  
Imaging Spectrometer ◽  
Airborne Imaging ◽  
A Charge

Abstract. We present a novel airborne imaging differential optical absorption spectroscopy (DOAS) instrument: the Ultraviolet Visible Hyperspectral Imaging Spectrometer (UVHIS), which is developed for trace gas monitoring and pollution mapping. Within a broad spectral range of 200 to 500 nm and operating in three channels, the spectral resolution of UVHIS is better than 0.5 nm. The optical design of each channel comprises a fore-optics with a field of view (FOV) of 40∘, an Offner imaging spectrometer and a charge-coupled device (CCD) array detector of 1032×1072 pixels. A first demonstration flight using UVHIS was conducted on 23 June 2018, above an area of approximately 600 km2 in Feicheng, China, with a spatial resolution of about 25 m×22 m. Measurements of nadir backscattered solar radiation of channel 3 are used to retrieve tropospheric vertical column densities (VCDs) of NO2 with a mean total error of 3.0×1015 molec cm−2. The UVHIS instrument clearly detected several emission plumes transporting from south to north, with a peak value of 3×1016 molec cm−2 in the dominant one. The UVHIS NO2 vertical columns are consistent with the ground-based mobile DOAS observations, with a correlation coefficient of 0.65 for all co-located measurements, a correlation coefficient of 0.86 for the co-located measurements that only circled the steel factory and a slight underestimation for the polluted observations. This study demonstrates the capability of UVHIS for NO2 local emission and transmission monitoring.

scholarly journals The automated patrol telescope

1986 ◽  
Vol 118 ◽  
pp. 85-86
Author(s):  
J. W. Cochrane ◽  
P. Mitchell ◽  
P. W. Payne ◽  
J. W. V. Storey ◽  
B. L. Webster
Keyword(s):  
New South ◽  
Array Detector ◽  
Schmidt Telescope ◽  
Charge Coupled Device ◽  
South Wales ◽  
Ccd Array ◽  
On Line ◽  
Computer Controlled ◽  
A Charge ◽  
North Western

A new astronomical system is nearing completion at U.N.S.W. in which a charge coupled device (CCD) array detector is matched to a Schmidt telescope, with the observations completely analyzed on-line. We have modified a Baker-Nunn satellite tracking camera, with its excellent 0.5m, f/1 super-Schmidt optics, converting it into a computer-controlled equatorially-mounted astronomical telescope. The telescope is expected to be located at Siding Spring Observatory in north-western New South Wales.

Man-Portable Laser-Induced Breakdown Spectroscopy System for in Situ Characterization of Karstic Formations

2008 ◽  
Vol 62 (11) ◽  
pp. 1250-1255 ◽  
Author(s):  
J. Cuñat ◽  
F. J. Fortes ◽  
L. M. Cabalín ◽  
F. Carrasco ◽  
M. D. Simón ◽  
...  
Keyword(s):  
Field Testing ◽  
Array Detector ◽  
Depth Information ◽  
Charge Coupled Device ◽  
Breakdown Spectroscopy ◽  
Ccd Array ◽  
Laser Induced Breakdown ◽  
Environment Identification ◽  
A Charge ◽  
Identification Analysis

This paper reports the development and field testing of a man-portable instrument based on laser-induced breakdown spectrometry (LIBS) for inspection and analysis of speleothems. The 50 mJ of a Q-switched Nd:YAG laser operating at 1064 nm was used to generate a plasma on the sample. Plasma emission was then guided using a fiber-optic cable to a 1/10 m spectrometer equipped with a charge-coupled device (CCD) array detector. Plasma light was automatically processed in order to obtain surface and in-depth information from the speleothems. A field campaign in the interior of Nerja Cave (a large karstic formation in the South of Spain) has been carried out, aimed at evaluating the analytical performance of the instrument when operating in an unfriendly environment. Identification analysis of the speleothems' alteration layers and depth profiles of Sr and Ca is carried out and reported.

scholarly journals Intercomparison of four airborne imaging DOAS systems for tropospheric NO<sub>2</sub> mapping – the AROMAPEX campaign

2019 ◽  
Vol 12 (1) ◽  
pp. 211-236 ◽  
Author(s):  
Frederik Tack ◽  
Alexis Merlaud ◽  
Andreas C. Meier ◽  
Tim Vlemmix ◽  
Thomas Ruhtz ◽  
...  
Keyword(s):  
Pearson Correlation ◽  
Wavelength Region ◽  
Correlation Coefficients ◽  
Horizontal Distribution ◽  
Primary Objective ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Vertical Column ◽  
Airborne Imaging ◽  
The City

Abstract. We present an intercomparison study of four airborne imaging DOAS instruments, dedicated to the retrieval and high-resolution mapping of tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs). The AROMAPEX campaign took place in Berlin, Germany, in April 2016 with the primary objective to test and intercompare the performance of experimental airborne imagers. The imaging DOAS instruments were operated simultaneously from two manned aircraft, performing synchronised flights: APEX (VITO–BIRA-IASB) was operated from DLR's DO-228 D-CFFU aircraft at 6.2 km in altitude, while AirMAP (IUP-Bremen), SWING (BIRA-IASB), and SBI (TNO–TU Delft–KNMI) were operated from the FUB Cessna 207T D-EAFU at 3.1 km. Two synchronised flights took place on 21 April 2016. NO2 slant columns were retrieved by applying differential optical absorption spectroscopy (DOAS) in the visible wavelength region and converted to VCDs by the computation of appropriate air mass factors (AMFs). Finally, the NO2 VCDs were georeferenced and mapped at high spatial resolution. For the sake of harmonising the different data sets, efforts were made to agree on a common set of parameter settings, AMF look-up table, and gridding algorithm. The NO2 horizontal distribution, observed by the different DOAS imagers, shows very similar spatial patterns. The NO2 field is dominated by two large plumes related to industrial compounds, crossing the city from west to east. The major highways A100 and A113 are also identified as line sources of NO2. Retrieved NO2 VCDs range between 1×1015 molec cm−2 upwind of the city and 20×1015 molec cm−2 in the dominant plume, with a mean of 7.3±1.8×1015 molec cm−2 for the morning flight and between 1 and 23×1015 molec cm−2 with a mean of 6.0±1.4×1015 molec cm−2 for the afternoon flight. The mean NO2 VCD retrieval errors are in the range of 22 % to 36 % for all sensors. The four data sets are in good agreement with Pearson correlation coefficients better than 0.9, while the linear regression analyses show slopes close to unity and generally small intercepts.

scholarly journals High-resolution airborne imaging DOAS measurements of NO<sub>2</sub> above Bucharest during AROMAT

2017 ◽  
Vol 10 (5) ◽  
pp. 1831-1857 ◽  
Author(s):  
Andreas Carlos Meier ◽  
Anja Schönhardt ◽  
Tim Bösch ◽  
Andreas Richter ◽  
André Seyler ◽  
...  
Keyword(s):  
Surface Properties ◽  
Urban Areas ◽  
Strong Dependence ◽  
Horizontal Distribution ◽  
Optical Absorption Spectroscopy ◽  
Surface Reflectance ◽  
Emission Rates ◽  
Vertical Column ◽  
Airborne Imaging ◽  
The City

Abstract. In this study we report on airborne imaging DOAS measurements of NO2 from two flights performed in Bucharest during the AROMAT campaign (Airborne ROmanian Measurements of Aerosols and Trace gases) in September 2014. These measurements were performed with the Airborne imaging Differential Optical Absorption Spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) and provide nearly gapless maps of column densities of NO2 below the aircraft with a high spatial resolution of better than 100 m. The air mass factors, which are needed to convert the measured differential slant column densities (dSCDs) to vertical column densities (VCDs), have a strong dependence on the surface reflectance, which has to be accounted for in the retrieval. This is especially important for measurements above urban areas, where the surface properties vary strongly. As the instrument is not radiometrically calibrated, we have developed a method to derive the surface reflectance from intensities measured by AirMAP. This method is based on radiative transfer calculation with SCIATRAN and a reference area for which the surface reflectance is known. While surface properties are clearly apparent in the NO2 dSCD results, this effect is successfully corrected for in the VCD results. Furthermore, we investigate the influence of aerosols on the retrieval for a variety of aerosol profiles that were measured in the context of the AROMAT campaigns. The results of two research flights are presented, which reveal distinct horizontal distribution patterns and strong spatial gradients of NO2 across the city. Pollution levels range from background values in the outskirts located upwind of the city to about 4  ×  1016 molec cm−2 in the polluted city center. Validation against two co-located mobile car-DOAS measurements yields good agreement between the datasets, with correlation coefficients of R =  0.94 and R =  0.85, respectively. Estimations on the NOx emission rate of Bucharest for the two flights yield emission rates of 15.1 ± 9.4 and 13.6 ± 8.4 mol s−1, respectively.

A Charge Coupled Device Array Detector for Single-Wavelength and Multiwavelength Ultraviolet Absorbance in Capillary Electrophoresis

1999 ◽  
Vol 71 (19) ◽  
pp. 4376-4384 ◽  
Author(s):  
Edmund T. Bergström ◽  
David M. Goodall ◽  
Boris Pokrić ◽  
Nigel M. Allinson
Keyword(s):  
Capillary Electrophoresis ◽  
Array Detector ◽  
Charge Coupled Device ◽  
Ultraviolet Absorbance ◽  
A Charge

scholarly journals High-resolution airborne imaging DOAS-measurements of NO<sub>2</sub> above Bucharest during AROMAT

2016 ◽  
Author(s):  
Andreas Carlos Meier ◽  
Anja Schönhardt ◽  
Tim Bösch ◽  
Andreas Richter ◽  
André Seyler ◽  
...  
Keyword(s):  
Surface Properties ◽  
Urban Areas ◽  
Strong Dependence ◽  
Horizontal Distribution ◽  
Optical Absorption Spectroscopy ◽  
Surface Reflectance ◽  
Emission Rates ◽  
Vertical Column ◽  
Airborne Imaging ◽  
The City

Abstract. In this study we report on airborne imaging DOAS measurements of NO2 from two flights performed in Bucharest during the AROMAT campaign (Airborne ROmanian Meeasurements of Aerosols an Trace gases) in September 2014. These measurements were performed with the Airborne imaging Differential Optical Absorption Spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) and provide nearly gapless maps of column densities of NO2 below the aircraft with a high spatial resolution of better than 100 m. The airmass factors, which are needed to convert the measured differential Slant Column Densities (dSCDs) to Vertical Column Densities (VCDs) have a strong dependence on the surface reflectance, which has to be accounted for in the retrieval. This is especially important for measurements above urban areas, where the surface properties vary strongly. As the instrument is not radiometrically calibrated, we have developed a method to derive the surface reflectance from measured intensities at the aircraft. This method is based on radiative transfer calculation with SCIATRAN and a reference area for which the surface reflectance is known. While surface properties are clearly seen in the NO2 dSCD results, this effect is successfully corrected for in the VCD results. Furthermore we investigate the influence of aerosols on the retrieval for a variety of aerosol profiles that were measured in the context of the AROMAT campaigns. The results of two research flights are presented which reveal distinct horizontal distribution patterns and strong spatial gradients of NO2 across the city. Pollution levels range from background values in the outskirts located upwind of the city to about 4 × 1016 molec cm−2 in the polluted city center. Validation against two co-located mobile car-DOAS measurements yields good agreement between the datasets with correlation cofficients of R = 0.94 and R = 0.85, respectively. Estimations on the NOx emission rate of Bucharest for the two flights yield emission rates of 15.1 &amp;pm; 9.4 mol s−1 and 13.6 &amp;pm; 8.4 mol s−1, respectively.

Absorbing Aerosol Sensor on Gao-Fen 5B satellite

2018 ◽  
Vol 7 (6) ◽  
pp. 387-393
Author(s):  
Entao Shi ◽  
Yongmei Wang ◽  
Nan Jia ◽  
Jinghua Mao ◽  
Guanda Lu ◽  
...  
Keyword(s):  
Mechanical Design ◽  
Optical Design ◽  
Large Field ◽  
Imaging Spectrometer ◽  
Charge Coupled Device ◽  
Backscatter Radiation ◽  
Global Coverage ◽  
Absorbing Aerosols ◽  
Cross Track ◽  
Wide Swath

Abstract The Absorbing Aerosol Sensor (AAS) will be launched aboard the GaoFen-5B satellite in China. The main purpose of AAS is to monitor absorbing aerosols by measuring the solar backscatter radiation. AAS is an ultraviolet-visible imaging spectrometer that uses a single charge coupled device to capture both the spectrum and the cross-track direction with a 114° wide swath. The large field of view enables daily global coverage with 4-km spatial resolution. The spectral range of the instrument extends from 340 to 550 nm with spectral resolution (full width at half maximum) of 2 nm. This paper provides details of the instrument design, including system design, optical design, and mechanical design, as well as detector and calibration unit on orbit. The numerous simulations show that all design results satisfy the specification and vibration requirements of the instrument.

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