scholarly journals O2 and OH Night Airglow Emission Derived from GOMOS-Envisat Instrument

2014 ◽  
Vol 31 (6) ◽  
pp. 1301-1311 ◽  
Author(s):  
Christophe Bellisario ◽  
Philippe Keckhut ◽  
Laurent Blanot ◽  
Alain Hauchecorne ◽  
Pierre Simoneau
Keyword(s):  
Error Analysis ◽  
Atmospheric Chemistry ◽  
Airglow Emission ◽  
Monthly Average ◽  
Stellar Occultation ◽  
Ozone Monitoring ◽  
Ccd Detectors ◽  
Absorption Measurements ◽  
Better Than ◽  
Night Airglow

Abstract Global Ozone Monitoring by Occultation of Stars (GOMOS) was an instrument dedicated to the study of atmospheric chemistry based on the principle of stellar occultation. The signals delivered by the IR spectrometer coupled with two CCD detectors, initially used for absorption measurements, were analyzed in order to observe the night airglow resulting from O2 and OH emissions at 761.9 and 930 nm, respectively. The method to retrieve those emissions is described as well as the error analysis. The results of this first attempt are presented and discussed with respect to instrument characteristics, earth coverage, altitude resolution, and the ability of GOMOS data to contribute to night airglow investigations. Mean limb intensities are equal to 28.9 and 7.7 MR for O2 at 760 nm and OH at 930 nm, respectively. Individual O2 emissions are retrieved with an accuracy better than 15%, while the OH emission, which provides smaller intensities, is retrieved with an accuracy of 10% for the monthly average.

scholarly journals GOMOS bright limb ozone data set

2015 ◽  
Vol 8 (8) ◽  
pp. 3107-3115 ◽  
Author(s):  
S. Tukiainen ◽  
E. Kyrölä ◽  
J. Tamminen ◽  
J. Kujanpää ◽  
L. Blanot
Keyword(s):  
Stray Light ◽  
Atmospheric Composition ◽  
Profile Data ◽  
Satellite Measurements ◽  
Data Set ◽  
Infrared Imager ◽  
Ozone Profile ◽  
Stellar Occultation ◽  
Ozone Monitoring ◽  
Better Than

Abstract. We have created a daytime ozone profile data set from the measurements of the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the Envisat satellite. This so-called GOMOS bright limb (GBL) data set contains ∼ 358 000 stratospheric daytime ozone profiles measured by GOMOS in 2002–2012. The GBL data set complements the widely used GOMOS nighttime data based on stellar occultation measurements. The GBL data set is based on the GOMOS daytime occultations but instead of the transmitted star light we use limb-scattered solar light. The ozone profiles retrieved from these radiance spectra cover the 18–60 km altitude range and have approximately 2–3 km vertical resolution. We show that these profiles are generally in better than 10 % agreement with the NDACC (Network for the Detection of Atmospheric Composition Change) ozonesonde profiles and with the GOMOS nighttime, MLS (Microwave Limb Sounder), and OSIRIS (Optical Spectrograph and InfraRed Imager System) satellite measurements. However, there is a 10–13 % negative bias at 40 km altitude and a 10–50 % positive bias at 50 km for solar zenith angles > 75°. These biases are most likely caused by stray light which is difficult to characterize and to remove entirely from the measured spectra. Nevertheless, the GBL data set approximately doubles the amount of useful GOMOS ozone profiles and improves coverage of the summer pole.

scholarly journals GEOMETRIC CALIBRATION OF ZIYUAN-3 THREE-LINE CAMERAS COMBINING GROUND CONTROL POINTS AND LINES

2016 ◽  
Vol XLI-B1 ◽  
pp. 163-168
Author(s):  
Jinshan Cao ◽  
Xiuxiao Yuan ◽  
Jianya Gong
Keyword(s):  
Ground Control ◽  
Calibration Model ◽  
Control Points ◽  
Charge Coupled Device ◽  
Geometric Calibration ◽  
Ground Control Points ◽  
The Look ◽  
Ccd Detectors ◽  
True Values ◽  
Better Than

Due to the large biases between the laboratory-calibrated values of the orientation parameters and their in-orbit true values, the initial direct georeferencing accuracy of the Ziyuan-3 (ZY-3) three-line camera (TLC) images can only reach the kilometre level. In this paper, a point-based geometric calibration model of the ZY-3 TLCs is firstly established by using the collinearity constraint, and then a line-based geometric calibration model is established by using the coplanarity constraint. With the help of both the point-based and the line-based models, a feasible in-orbit geometric calibration approach for the ZY-3 TLCs combining ground control points (GCPs) and ground control lines (GCLs) is presented. Experimental results show that like GCPs, GCLs can also provide effective ground control information for the geometric calibration of the ZY-3 TLCs. The calibration accuracy of the look angles of charge-coupled device (CCD) detectors achieved by using the presented approach reached up to about 1.0''. After the geometric calibration, the direct georeferencing accuracy of the ZY-3 TLC images without ground controls was significantly improved from the kilometre level to better than 11 m in planimetry and 9 m in height. A more satisfactory georeferencing accuracy of better than 3.5 m in planimetry and 3.0 m in height was achieved after the block adjustment with four GCPs.

scholarly journals Effect of Solar Tilt Angles on Photovoltaic Module Performance: A Behavioral Optimization Approach

2020 ◽  
pp. 90-102
Author(s):  
Trina Som ◽  
A. Sharma ◽  
D. Thakur
Keyword(s):  
Solar Energy ◽  
Tilt Angle ◽  
Photovoltaic Module ◽  
Optimization Approach ◽  
Solar Module ◽  
Monthly Average ◽  
Pv Module ◽  
Yearly Maximum ◽  
Module Performance ◽  
Better Than

In the present study, performance analyses of a solar module are made through the optimal variation of solar tilt angle, pertaining to the maximum generation of solar energy. The work has been carried out for a particular location at Tripura, in India, considering three different cases on an annual basis. An intelligent behavioural based algorithm, known as artificial bee algorithm (ABC), has been implemented for finding the optimal orientation of solar angle in analysing the performance. The result shows marginal differences are obtained in producing yearly maximum solar energy for different orientations of the PV module. It has been observed that the maximum average solar energy is obtained for the case where continuous adjustment is made by rotating the plane about the horizontal east-west axis within 20° to 30° tilt angle. The computed maximum and minimum of the monthly average efficiency is 10.9% and 8.7%, respectively. Further, a comparative study has been performed in generating average solar energy through optimal tilt angle by the implementation of Perturb & Observe method (P&O). The monthly average solar power computed by P&O method resulted better in a range of 2% to 15% in comparison to that obtained by ABC. While on the other hand, the efficiency computed by ABC algorithm was 15% to 19% better than that evaluated by P&O method for all the cases studied in the present work.

scholarly journals Aerosol extinction profiles at 525 nm and 1020 nm derived from ACE imager data: comparisons with GOMOS, SAGE II, SAGE III, POAM III, and OSIRIS

2008 ◽  
Vol 8 (7) ◽  
pp. 2027-2037 ◽  
Author(s):  
F. Vanhellemont ◽  
C. Tetard ◽  
A. Bourassa ◽  
M. Fromm ◽  
J. Dodion ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Trace Gas ◽  
Aerosol Extinction ◽  
Optical Extinction ◽  
Solar Occultation ◽  
Comparison Results ◽  
Stellar Occultation ◽  
Relative Differences ◽  
Atmospheric Trace Gas ◽  
Chemistry Experiment

Abstract. The Canadian ACE (Atmospheric Chemistry Experiment) mission is dedicated to the retrieval of a large number of atmospheric trace gas species using the solar occultation technique in the infrared and UV/visible spectral domain. However, two additional solar disk imagers (at 525 nm and 1020 nm) were added for a number of reasons, including the retrieval of aerosol and cloud products. In this paper, we present first comparison results for these imager aerosol/cloud optical extinction coefficient profiles, with the ones derived from measurements performed by 3 solar occultation instruments (SAGE II, SAGE III, POAM III), one stellar occultation instrument (GOMOS) and one limb sounder (OSIRIS). The results indicate that the ACE imager profiles are of good quality in the upper troposphere/lower stratosphere, although the aerosol extinction for the visible channel at 525 nm contains a significant negative bias at higher altitudes, while the relative differences indicate that ACE profiles are almost always too high at 1020 nm. Both problems are probably related to ACE imager instrumental issues.

scholarly journals CO measurements from the ACE-FTS satellite instrument: data analysis and validation using ground-based, airborne and spaceborne observations

2008 ◽  
Vol 8 (9) ◽  
pp. 2569-2594 ◽  
Author(s):  
C. Clerbaux ◽  
M. George ◽  
S. Turquety ◽  
K. A. Walker ◽  
B. Barret ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Atmospheric Chemistry ◽  
Measurement Data ◽  
Upper Troposphere ◽  
Remote Sensors ◽  
Key Species ◽  
Vibrational Bands ◽  
Good Tracer ◽  
Chemistry Experiment ◽  
Better Than

Abstract. The Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Carbon monoxide (CO), a good tracer of pollution plumes and atmospheric dynamics, is one of the key species provided by the primary instrument, the ACE-Fourier Transform Spectrometer (ACE-FTS). This instrument performs measurements in both the CO 1-0 and 2-0 ro-vibrational bands, from which vertically resolved CO concentration profiles are retrieved, from the mid-troposphere to the thermosphere. This paper presents an updated description of the ACE-FTS version 2.2 CO data product, along with a comprehensive validation of these profiles using available observations (February 2004 to December 2006). We have compared the CO partial columns with ground-based measurements using Fourier transform infrared spectroscopy and millimeter wave radiometry, and the volume mixing ratio profiles with airborne (both high-altitude balloon flight and airplane) observations. CO satellite observations provided by nadir-looking instruments (MOPITT and TES) as well as limb-viewing remote sensors (MIPAS, SMR and MLS) were also compared with the ACE-FTS CO products. We show that the ACE-FTS measurements provide CO profiles with small retrieval errors (better than 5% from the upper troposphere to 40 km, and better than 10% above). These observations agree well with the correlative measurements, considering the rather loose coincidence criteria in some cases. Based on the validation exercise we assess the following uncertainties to the ACE-FTS measurement data: better than 15% in the upper troposphere (8–12 km), than 30% in the lower stratosphere (12–30 km), and than 25% from 30 to 100 km.

Frequency Distributions for Hourly and Daily Clearness Indices

2001 ◽  
Vol 124 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Manuel Iban˜ez ◽  
William A. Beckman ◽  
Sanford A. Klein
Keyword(s):  
Solar Radiation ◽  
Recent Literature ◽  
Weather Data ◽  
Clearness Index ◽  
Frequency Distributions ◽  
Monthly Average ◽  
Daily Frequency ◽  
Better Than ◽  
Exponential Probability

The clearness index for hourly and daily radiation is an important parameter in describing solar radiation. Liu and Jordan demonstrated that the monthly average daily clearness index could be used to predict the long-term distribution of daily solar radiation in a month. This paper reviews recent literature on the prediction of hourly and daily frequency distributions and cumulative frequency distributions of clearness indices. Ten years of measured weather data for six cities in the U.S. are used to investigate the nature of the hourly and daily frequency distributions. A second set of ten years of data for six cities is used to verify the predictions. A bi-exponential probability density function is proposed that fits the observed bimodal nature of the data better than existing models. A case is made for the function being universal.

scholarly journals Validation of SMILES HCl profiles over a wide range from the stratosphere to the lower thermosphere

2020 ◽  
Vol 13 (12) ◽  
pp. 6837-6852
Author(s):  
Seidai Nara ◽  
Tomohiro O. Sato ◽  
Takayoshi Yamada ◽  
Tamaki Fujinawa ◽  
Kota Kuribayashi ◽  
...  
Keyword(s):  
Error Analysis ◽  
Atmospheric Chemistry ◽  
Vertical Profile ◽  
Climate Model ◽  
Lower Thermosphere ◽  
Atmospheric Temperature ◽  
Vertical Profiles ◽  
Theoretical Error ◽  
Wide Range ◽  
The Difference

Abstract. Hydrogen chloride (HCl) is the most abundant (more than 95 %) among inorganic chlorine compounds Cly in the upper stratosphere. The HCl molecule is observed to obtain long-term quantitative estimations of the total budget of the stratospheric chlorine compounds. In this study, we provided HCl vertical profiles at altitudes of 16–100 km using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) from space. The HCl vertical profile from the upper troposphere to the lower thermosphere is reported for the first time from SMILES observations; the data quality is quantified by comparison with other measurements and via theoretical error analysis. We used the SMILES level-2 research product version 3.0.0. The period of the SMILES HCl observation was from 12 October 2009 to 21 April 2010, and the latitude coverage was 40∘ S–65∘ N. The average HCl vertical profile showed an increase with altitude up to the stratopause (∼ 45 km), approximately constant values between the stratopause and the upper mesosphere (∼ 80 km), and a decrease from the mesopause to the lower thermosphere (∼ 100 km). This behavior was observed in all latitude regions and reproduced by the Whole Atmosphere Community Climate Model in the specified dynamics configuration (SD-WACCM). We compared the SMILES HCl vertical profiles in the stratosphere and lower mesosphere with HCl profiles from Microwave Limb Sounder (MLS) on the Aura satellite, as well as from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on SCISAT and the TErahertz and submillimeter LImb Sounder (TELIS) (balloon borne). The TELIS observations were performed using the superconductive limb emission technique, as used by SMILES. The globally averaged vertical HCl profiles of SMILES agreed well with those of MLS and ACE-FTS within 0.25 and 0.2 ppbv between 20 and 40 km (within 10 % between 30 and 40 km; there is a larger discrepancy below 30 km), respectively. The SMILES HCl concentration was smaller than those of MLS and ACE-FTS as the altitude increased from 40 km, and the difference was approximately 0.4–0.5 ppbv (12 %–15 %) at 50–60 km. The difference between SMILES and TELIS HCl observations was about 0.3 ppbv in the polar winter region between 20 and 34 km, except near 26 km. SMILES HCl error sources that may cause discrepancies with the other observations are investigated by a theoretical error analysis. We calculated errors caused by the uncertainties of spectroscopic parameters, instrument functions, and atmospheric temperature profiles. The Jacobian for the temperature explains the negative bias of the SMILES HCl concentrations at 50–60 km.

scholarly journals MULTICHARME: A modified Chernin-type multi-pass cell designed for IR and THz long-path absorption measurements in the CHARME atmospheric simulation chamber

2021 ◽  
Author(s):  
Jean Decker ◽  
Éric Fertein ◽  
Jonas Bruckhuisen ◽  
Nicolas Houzel ◽  
Pierre Kulinski ◽  
...  
Keyword(s):  
Polar Compounds ◽  
Thz Spectroscopy ◽  
Near Ir ◽  
Atmospheric Reactivity ◽  
High Degree ◽  
First Time ◽  
Effective Reflectivity ◽  
Simulation Chamber ◽  
Absorption Measurements ◽  
Better Than

Abstract. We have developed MULTICHARME, a modified Chernin-type multi-pass cell especially designed for IR and THz long-path absorption measurements in the CHamber for Atmospheric Reactivity and Metrology of the Environment (CHARME). By measuring the output power using a near-IR diode-laser and a THz amplified multiplication chain, we have established that the effective reflectivity of MULTICHARME is better than 94 % over approximately three decades of frequency. Absorption measurements of N2O have been performed by probing highly excited rovibrational transitions in the near-IR and ground state rotational transitions at submillimetre wavelengths. In each case the linearity of the absorbance with the pathlengths was verified. Finally, we demonstrate that THz spectroscopy is able to study the isotopic composition of greenhouse polar gases such as N2O and to absolutely quantify stable (N2O) and reactive (O3) species at trace levels. Moreover, a THz monitoring at low pressure of the ozone decay in the chamber has been performed. The deduced ozone lifetime of 3.4 ± 0.1 h is shorter compared with previous measurements performed in CHARME at atmospheric pressure. For the first time, the ability of THz rotational spectroscopy to monitor, with a very high degree of selectivity, stable and reactive polar compounds at trace level in an atmospheric simulation chamber is demonstrated. However, the sensitivity of the THz monitoring needs to be improved to reach the atmospheric trace levels. For this purpose, it is necessary to figure out the baseline variations as well as possible induced by the multiple standing waves present in MULTICHARME.

scholarly journals Retrievals from GOMOS stellar occultation measurements using characterization of modeling errors

2010 ◽  
Vol 3 (1) ◽  
pp. 579-597 ◽  
Author(s):  
V. F. Sofieva ◽  
J. Vira ◽  
E. Kyrölä ◽  
J. Tamminen ◽  
V. Kan ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Large Data ◽  
Inversion Algorithm ◽  
Data Set ◽  
High Importance ◽  
Numerical Efficiency ◽  
Modeling Errors ◽  
Stellar Occultation ◽  
Ozone Monitoring

Abstract. In this paper, we discuss the development of the inversion algorithm for the GOMOS (Global Ozone Monitoring by Occultation of Star) instrument on board the Envisat satellite. The proposed algorithm takes accurately into account the wavelength-dependent modeling errors, which are mainly due to the incomplete scintillation correction in the stratosphere. The special attention is paid to numerical efficiency of the algorithm. The developed method is tested on a large data set and its advantages are demonstrated. Its main advantage is a proper characterization of the uncertainties of the retrieved profiles of atmospheric constituents, which is of high importance for data assimilation, trend analyses and validation.

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