scholarly journals The “ideal” spectrograph for atmospheric observations

2021 ◽  
Vol 14 (10) ◽  
pp. 6867-6883
Author(s):  
Ulrich Platt ◽  
Thomas Wagner ◽  
Jonas Kuhn ◽  
Thomas Leisner
Keyword(s):  
Low Earth Orbit ◽  
Optimal Size ◽  
Atmospheric Gases ◽  
Near Ir ◽  
Many Instruments ◽  
Atmospheric Observations ◽  
New Ideas ◽  
Spectral Ranges ◽  
Atmospheric Trace Gas

Abstract. Spectroscopy of scattered sunlight in the near-UV to near-IR spectral ranges has proven to be an extremely useful tool for the analysis of atmospheric trace gas distributions. A central parameter for the achievable sensitivity and spatial resolution of spectroscopic instruments is the étendue (product of aperture angle and entrance area) of the spectrograph, which is at the heart of the instrument. The étendue of an instrument can be enhanced by (1) upscaling all instrument dimensions or (2) by changing the instrument F number, (3) by increasing the entrance area, or (4) by operating many instruments (of identical design) in parallel. The étendue can be enhanced by (in principle) arbitrary factors by options (1) and (4); the effect of options (2) and (3) is limited. We present some new ideas and considerations of how instruments for the spectroscopic determination of atmospheric gases could be optimized using new possibilities in spectrograph design and manufacturing. Particular emphasis is on arrays of massively parallel instruments for observations using scattered sunlight. Such arrays can reduce size and weight of instruments by orders of magnitude while preserving spectral resolution and light throughput. We also discuss the optimal size of individual spectrographs in a spectrograph array and give examples of spectrograph systems for use on a (low Earth orbit) satellite, including one with sub-kilometre ground pixel size.

scholarly journals The “Ideal Spectrograph” for Atmospheric Observations

2021 ◽  
Author(s):  
Ulrich Platt ◽  
Thomas Wagner ◽  
Jonas Kuhn ◽  
Thomas Leisner
Keyword(s):  
Low Earth Orbit ◽  
Optimal Size ◽  
Atmospheric Gases ◽  
Near Ir ◽  
Many Instruments ◽  
Atmospheric Observations ◽  
New Ideas ◽  
Spectral Ranges ◽  
Atmospheric Trace Gas

Abstract. Spectroscopy of scattered-sunlight in the near UV to near IR spectral ranges has proven to be an extremely useful tool for the analysis of atmospheric trace gas distributions. A central parameter for the achievable sensitivity and spatial resolution of spectroscopic instruments is the étendue (product of aperture angle and entrance area) of the spectrograph, which is at the heart of the instrument. The étendue of an instrument can be enhanced by (1) up-scaling all instrument dimensions or (2) by changing the instrument F-number, (3) by increasing the entrance area, or (4) by operating many instruments (of identical design) in parallel. The étendue can be enhanced by (in principle) arbitrary factors by options (1) and (4), the effect of options (2) and (3) is limited. We present some new ideas and considerations how instruments for the spectroscopic determination of atmospheric gases could be optimized by using new possibilities in spectrograph design and manufacturing. Particular emphasis is on arrays of massively parallel instruments for observations using scattered-sunlight. Such arrays can reduce size and weight of instruments by orders of magnitude, while preserving spectral resolution and light throughput. We also discuss the optimal size of individual spectrographs in a spectrograph array and give examples of spectrograph systems for use on a (low Earth orbit) satellite including one with sub-km ground pixel size.

scholarly journals The “Ideal Spectrograph” for Atmospheric Observations

2021 ◽  
Author(s):  
Ulrich Platt ◽  
Thomas Wagner ◽  
Jonas Kuhn ◽  
Thomas Leisner
Keyword(s):  
Low Earth Orbit ◽  
Optimal Size ◽  
Atmospheric Gases ◽  
Near Ir ◽  
Many Instruments ◽  
Atmospheric Observations ◽  
New Ideas ◽  
Global Coverage ◽  
Spectral Ranges ◽  
Atmospheric Trace Gas

<p>The analysis of atmospheric trace gas distributions by absorption spectroscopy of scattered sunlight in the near UV to near IR spectral ranges has proven to be extremely useful. A central parameter for the achievable sensitivity and spatial resolution of spectroscopic instruments is the étendue (product of aperture angle and entrance area) of the spectrograph, which is at the heart of the instrument. The étendue of an instrument can be enhanced by (1) up-scaling all instrument dimensions or (2) by changing the instrument F-number, (3) by increasing the entrance area, or (4) by operating many instruments (of identical design) in parallel. While options (1) and (4) allow enhancement by (in principle) arbitrary factors, the effect of options (2) and (3) and measures like better grating efficiency is limited.</p><p>We present new ideas and considerations on how instruments for the spectroscopic determination of atmospheric gases could be optimized with respect to étendue per volume (or mass) by using new possibilities in spectrograph design and manufacturing. Particular emphasis is on arrays of massively parallel instruments for observations using scattered sunlight. Such arrays can reduce size and weight of instruments by orders of magnitude, while preserving spectral resolution and light throughput. We also discuss the optimal size of individual spectrographs in a spectrograph array and give examples of grating spectrograph systems for use on a (low Earth orbit) satellite including one with sub-km ground pixel size and daily global coverage.</p>

scholarly journals The Empirical and Theoretical Miscible Characterization Method in Gas-Enhanced Oil Recovery

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Wang Chengjun ◽  
Li Xiaorui
Keyword(s):  
Oil Recovery ◽  
Research Result ◽  
Empirical Method ◽  
Reservoir Engineering ◽  
Forecasting Accuracy ◽  
Factors Affecting ◽  
Development Scheme ◽  
Gas Flooding ◽  
New Ideas

The determination of miscible characteristic is one of the key technologies for enhancing oil recovery of gas flooding. If the miscible characteristic at each development period of gas flooding can be known in real time, it will be helpful to guide gas flooding development scheme. The minimum miscible pressure (MMP) is mostly used to describe miscible characteristic. Currently, the MMP forecasting methods can be classified into two categories—the empirical method and theoretical calculation method. In this paper, the main controlling factors affecting MMP are analyzed combined with reservoir engineering method, phase equilibrium theory, reservoir numerical simulation technology, and so on. Based on this, new empirical and theoretical MMP forecasting model was built. Meanwhile, new ideas for improving forecasting accuracy through modifying miscible criterion were proposed. The calculation accuracies of the two MMP forecasting models can be improved to over 90% that is more accurate and adapted than other methods. This research result can supply new ideas for gas flooding MMP forecasting.

Near-IR Spectroscopic Determination of NaCl in Aqueous Solution

1992 ◽  
Vol 46 (12) ◽  
pp. 1809-1815 ◽  
Author(s):  
Jie Lin ◽  
Chris W. Brown
Keyword(s):  
Aqueous Solution ◽  
Temperature Effects ◽  
Continuous Monitoring ◽  
Principal Component Regression ◽  
Principal Component ◽  
Standard Errors ◽  
Near Ir ◽  
Linear And Nonlinear ◽  
Ir Spectroscopic

The concentrations of NaCl in aqueous solutions have been determined with the use of near-IR spectra between 1100 and 1900 nm. Models expressing the concentration of NaCl are developed with linear and nonlinear regression with the use of the absorbances at selected wavelengths and with principal component regression (PCR) using entire spectra. Temperature perturbations on water bands interfere with the measurement of NaCl but can be removed by linear or nonlinear regressions using the absorbances at the wavelengths where the temperature effects are zero, or they can be accounted for by PCR. Standard errors of 5 mM and a detection limit of IS mM are obtained for NaCl. This technique can be applied for quantitative analysis of NaCl in the laboratory or can be readily adapted for continuous monitoring in process control.

scholarly journals Orbit Propagation and Determination of Low Earth Orbit Satellites

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Ho-Nien Shou
Keyword(s):  
Kalman Filter ◽  
Real Time ◽  
Unscented Kalman Filter ◽  
Estimation Method ◽  
Nonlinear Problems ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Positioning Accuracy ◽  
Orbit Propagation

This paper represents orbit propagation and determination of low Earth orbit (LEO) satellites. Satellite global positioning system (GPS) configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP). The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan to use a nonlinear filtering method for immediate orbit tasks requires more precise satellite orbit state parameters in a short time. Although the traditional extended Kalman filter (EKF) method is widely used, its linear approximation of the drawbacks in dealing with nonlinear problems was especially evident, without compromising Kalman filter (unscented Kalman Filter, UKF). As a new nonlinear estimation method, it is measured at the estimated measurements on more and more applications. This paper will be the first study on UKF microsatellites in LEO orbit in real time, trying to explore the real-time precision orbit determination techniques. Through the preliminary simulation results, they show that, based on orbit mission requirements and conditions using UKF, they can satisfy the positioning accuracy and compute two indicators.

AN EASY APPROACH FOR ESTIMATING ABSORPTION LOSS IN ORGANIC THIN SOLID FILMS

1999 ◽  
Vol 08 (04) ◽  
pp. 519-525
Author(s):  
SHEN YUQUAN ◽  
LI ZHAO ◽  
ZHAO YUXIA ◽  
ZHAI JIANFENG ◽  
ZHOU JIAYUN ◽  
...  
Keyword(s):  
Spectroscopic Method ◽  
Optical Loss ◽  
Polymeric Films ◽  
Absorption Loss ◽  
Optical Losses ◽  
Thin Solid Films ◽  
Solid Films ◽  
Near Ir ◽  
Ir Spectroscopic

An UV-VIS-Near-IR spectroscopic method for determination of optical loss in organic/polymeric films has been suggested. The optical losses of two polyimide polymers with push-pull azobenzene chromophore attached were examined by this method and the data were calibrated by conventional optical method.

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