scholarly journals Proposed standardized definitions for vertical resolution and uncertainty in the NDACC lidar ozone and temperature algorithms – Part 3: Temperature uncertainty budget

2016 ◽  
Author(s):  
Thierry Leblanc ◽  
Robert J. Sica ◽  
J. Anne E. van Gijsel ◽  
Alexander Haefele ◽  
Guillaume Payen ◽  
...  
Keyword(s):  
Data Processing ◽  
Cross Sections ◽  
A Priori ◽  
Uncertainty Budget ◽  
Standard Uncertainty ◽  
Atmospheric Composition ◽  
Mauna Loa ◽  
Processing Chain ◽  
Acceleration Of Gravity ◽  
The Individual

Abstract. A standardized approach for the definition, propagation and reporting of uncertainty in the temperature lidar data products contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database is proposed. One important aspect of the proposed approach is the ability to propagate all independent uncertainty components in parallel through the data processing chain. The individual uncertainty components are then combined together at the very last stage of processing to form the temperature combined standard uncertainty. The identified individual uncertainty components comprise signal detection uncertainty, uncertainty due to saturation correction, background noise extraction, the merging of multiple channels, the absorption cross-sections of ozone and NO2, the molecular extinction cross-sections, the a priori use of ancillary air, ozone, and NO2 number density, the a priori use of ancillary temperature to tie-on the top of the profile, the acceleration of gravity, and the molecular mass of air. The expression of the individual uncertainty components and their step-by-step propagation through the temperature data processing chain are thoroughly estimated. All sources of uncertainty except detection noise imply correlated terms in the vertical dimension, which means that covariance terms must be taken into account when vertical filtering is applied and when temperature is integrated form the top of the profile. Quantitatively, the uncertainty budget is presented in a generic form (i.e., as a function of instrument performance and wavelength), so that any NDACC temperature lidar investigator can easily estimate the expected impact of individual uncertainty components in the case of their own instrument. An example of a full uncertainty budget obtained from actual measurements by the JPL lidar at the Mauna Loa Observatory is also provided.

scholarly journals Proposed standardized definitions for vertical resolution and uncertainty in the NDACC lidar ozone and temperature algorithms – Part 2: Ozone DIAL uncertainty budget

2016 ◽  
Author(s):  
Thierry Leblanc ◽  
Robert Sica ◽  
J. Anne E. van Gijsel ◽  
Sophie Godin-Beekmann ◽  
Alexander Haefele ◽  
...  
Keyword(s):  
Cross Sections ◽  
Stratospheric Ozone ◽  
Random Noise ◽  
Uncertainty Budget ◽  
Standard Uncertainty ◽  
Atmospheric Composition ◽  
Uncertainty Component ◽  
Mauna Loa ◽  
Processing Chain ◽  
The Individual

Abstract. A standardized approach for the definition, propagation and reporting of uncertainty in the ozone differential absorption lidar data products contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database is proposed. One essential aspect of the proposed approach is the propagation in parallel of all independent uncertainty components through the data processing chain before they are combined together to form the ozone combined standard uncertainty. The independent uncertainty components contributing to the overall budget include random noise associated with signal detection, uncertainty due to saturation correction, background noise extraction, the absorption cross-sections of ozone, NO2, SO2, and O2, the molecular extinction cross-sections, and the number densities of the air, NO2, and SO2. The expression of the individual uncertainty components and their step-by-step propagation through the ozone DIAL processing chain are thoroughly estimated. All sources of uncertainty except detection noise imply correlated terms in the vertical dimension, which requires knowledge of the covariance matrix when the lidar signal is vertically filtered. In addition, the covariance terms must be taken into account if the same detection hardware is shared by the lidar receiver channels at the absorbed and non-absorbed wavelengths. The ozone uncertainty budget is presented as much as possible in generic form (i.e., as a function of instrument performance and wavelength) so that all NDACC ozone DIAL investigators across the network can estimate, for their own instrument and in a straightforward manner, the expected impact of each reviewed uncertainty component. In addition, two actual examples of full uncertainty budget are provided, using measurements from the tropospheric ozone DIAL located at the JPL-Table Mountain Facility, California, and measurements from the JPL stratospheric ozone DIAL located at Mauna Loa Observatory, Hawaii.

scholarly journals Proposed standardized definitions for vertical resolution and uncertainty in the NDACC lidar ozone and temperature algorithms – Part 2: Ozone DIAL uncertainty budget

2016 ◽  
Vol 9 (8) ◽  
pp. 4051-4078 ◽  
Author(s):  
Thierry Leblanc ◽  
Robert J. Sica ◽  
Joanna A. E. van Gijsel ◽  
Sophie Godin-Beekmann ◽  
Alexander Haefele ◽  
...  
Keyword(s):  
Cross Sections ◽  
Stratospheric Ozone ◽  
Random Noise ◽  
Uncertainty Budget ◽  
Standard Uncertainty ◽  
Atmospheric Composition ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Processing Chain ◽  
The Individual

Abstract. A standardized approach for the definition, propagation, and reporting of uncertainty in the ozone differential absorption lidar data products contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database is proposed. One essential aspect of the proposed approach is the propagation in parallel of all independent uncertainty components through the data processing chain before they are combined together to form the ozone combined standard uncertainty. The independent uncertainty components contributing to the overall budget include random noise associated with signal detection, uncertainty due to saturation correction, background noise extraction, the absorption cross sections of O3, NO2, SO2, and O2, the molecular extinction cross sections, and the number densities of the air, NO2, and SO2. The expression of the individual uncertainty components and their step-by-step propagation through the ozone differential absorption lidar (DIAL) processing chain are thoroughly estimated. All sources of uncertainty except detection noise imply correlated terms in the vertical dimension, which requires knowledge of the covariance matrix when the lidar signal is vertically filtered. In addition, the covariance terms must be taken into account if the same detection hardware is shared by the lidar receiver channels at the absorbed and non-absorbed wavelengths. The ozone uncertainty budget is presented as much as possible in a generic form (i.e., as a function of instrument performance and wavelength) so that all NDACC ozone DIAL investigators across the network can estimate, for their own instrument and in a straightforward manner, the expected impact of each reviewed uncertainty component. In addition, two actual examples of full uncertainty budget are provided, using nighttime measurements from the tropospheric ozone DIAL located at the Jet Propulsion Laboratory (JPL) Table Mountain Facility, California, and nighttime measurements from the JPL stratospheric ozone DIAL located at Mauna Loa Observatory, Hawai'i.

scholarly journals Proposed standardized definitions for vertical resolution and uncertainty in the NDACC lidar ozone and temperature algorithms – Part 3: Temperature uncertainty budget

2016 ◽  
Vol 9 (8) ◽  
pp. 4079-4101 ◽  
Author(s):  
Thierry Leblanc ◽  
Robert J. Sica ◽  
Joanna A. E. van Gijsel ◽  
Alexander Haefele ◽  
Guillaume Payen ◽  
...  
Keyword(s):  
Data Processing ◽  
Background Noise ◽  
Random Noise ◽  
Uncertainty Budget ◽  
Extraction Temperature ◽  
Altitude Range ◽  
Total Uncertainty ◽  
Sources Of Uncertainty ◽  
Processing Chain ◽  
The Individual

Abstract. A standardized approach for the definition, propagation, and reporting of uncertainty in the temperature lidar data products contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database is proposed. One important aspect of the proposed approach is the ability to propagate all independent uncertainty components in parallel through the data processing chain. The individual uncertainty components are then combined together at the very last stage of processing to form the temperature combined standard uncertainty. The identified uncertainty sources comprise major components such as signal detection, saturation correction, background noise extraction, temperature tie-on at the top of the profile, and absorption by ozone if working in the visible spectrum, as well as other components such as molecular extinction, the acceleration of gravity, and the molecular mass of air, whose magnitudes depend on the instrument, data processing algorithm, and altitude range of interest. The expression of the individual uncertainty components and their step-by-step propagation through the temperature data processing chain are thoroughly estimated, taking into account the effect of vertical filtering and the merging of multiple channels. All sources of uncertainty except detection noise imply correlated terms in the vertical dimension, which means that covariance terms must be taken into account when vertical filtering is applied and when temperature is integrated from the top of the profile. Quantitatively, the uncertainty budget is presented in a generic form (i.e., as a function of instrument performance and wavelength), so that any NDACC temperature lidar investigator can easily estimate the expected impact of individual uncertainty components in the case of their own instrument. Using this standardized approach, an example of uncertainty budget is provided for the Jet Propulsion Laboratory (JPL) lidar at Mauna Loa Observatory, Hawai'i, which is typical of the NDACC temperature lidars transmitting at 355 nm. The combined temperature uncertainty ranges between 0.1 and 1 K below 60 km, with detection noise, saturation correction, and molecular extinction correction being the three dominant sources of uncertainty. Above 60 km and up to 10 km below the top of the profile, the total uncertainty increases exponentially from 1 to 10 K due to the combined effect of random noise and temperature tie-on. In the top 10 km of the profile, the accuracy of the profile mainly depends on that of the tie-on temperature. All other uncertainty components remain below 0.1 K throughout the entire profile (15–90 km), except the background noise correction uncertainty, which peaks around 0.3–0.5 K. It should be kept in mind that these quantitative estimates may be very different for other lidar instruments, depending on their altitude range and the wavelengths used.

scholarly journals A Distributed Modular Data Processing Chain Applied to Simulated Satellite Ozone Observations

2021 ◽  
Vol 13 (2) ◽  
pp. 210
Author(s):  
Marco Gai ◽  
Flavio Barbara ◽  
Simone Ceccherini ◽  
Ugo Cortesi ◽  
Samuele Del Bianco ◽  
...  
Keyword(s):  
Data Processing ◽  
Uv Radiation ◽  
Processing System ◽  
Simulated Data ◽  
General Purpose ◽  
Low Earth Orbit ◽  
Atmospheric Composition ◽  
General Purpose Technologies ◽  
Processing Chain ◽  
Novel Approach

Remote sensing of the atmospheric composition from current and future satellites, such as the Sentinel missions of the Copernicus programme, yields an unprecedented amount of data to monitor air quality, ozone, UV radiation and other climate variables. Hence, full exploitation of the growing wealth of information delivered by spaceborne observing systems requires addressing the technological challenges for developing new strategies and tools that are capable to deal with these huge data volumes. The H2020 AURORA (Advanced Ultraviolet Radiation and Ozone Retrieval for Applications) project investigated a novel approach for synergistic use of ozone profile measurements acquired at different frequencies (ultraviolet, visible, thermal infrared) by sensors onboard Geostationary Equatorial Orbit (GEO) and Low Earth Orbit (LEO) satellites in the framework of the Copernicus Sentinel-4 and Sentinel-5 missions. This paper outlines the main features of the technological infrastructure, designed and developed to support the AURORA data processing chain as a distributed data processing and describes in detail the key components of the infrastructure and the software prototype. The latter demonstrates the technical feasibility of the automatic execution of the full processing chain with simulated data. The Data Processing Chain (DPC) presented in this work thus replicates a processing system that, starting from the operational satellite retrievals, carries out their fusion and results in the assimilation of the fused products. These consist in ozone vertical profiles from which further modules of the chain deliver tropospheric ozone and UV radiation at the Earth’s surface. The conclusions highlight the relevance of this novel approach to the synergistic use of operational satellite data and underline that the infrastructure uses general-purpose technologies and is open for applications in different contexts.

scholarly journals An improved total and tropospheric NO<sub>2</sub> column retrieval for GOME-2

2019 ◽  
Vol 12 (2) ◽  
pp. 1029-1057 ◽  
Author(s):  
Song Liu ◽  
Pieter Valks ◽  
Gaia Pinardi ◽  
Isabelle De Smedt ◽  
Huan Yu ◽  
...  
Keyword(s):  
Cross Sections ◽  
Column Density ◽  
Transport Model ◽  
A Priori ◽  
Estimation Algorithm ◽  
Reference Points ◽  
Atmospheric Composition ◽  
Optical Absorption Spectroscopy ◽  
Air Mass ◽  
Tropospheric No2

Abstract. An improved algorithm for the retrieval of total and tropospheric nitrogen dioxide (NO2) columns from the Global Ozone Monitoring Experiment-2 (GOME-2) is presented. The refined retrieval will be implemented in a future version of the GOME Data Processor (GDP) as used by the EUMETSAT Satellite Application Facility on Atmospheric Composition and UV Radiation (AC-SAF). The first main improvement is the application of an extended 425–497 nm wavelength fitting window in the differential optical absorption spectroscopy (DOAS) retrieval of the NO2 slant column density, based on which initial total NO2 columns are computed using stratospheric air mass factors (AMFs). Updated absorption cross sections and a linear offset correction are used for the large fitting window. An improved slit function treatment is applied to compensate for both long-term and in-orbit drift of the GOME-2 slit function. Compared to the current operational (GDP 4.8) dataset, the use of these new features increases the NO2 columns by ∼1–3×1014 molec cm2 and reduces the slant column error by ∼24 %. In addition, the bias between GOME-2A and GOME-2B measurements is largely reduced by adopting a new level 1b data version in the DOAS retrieval. The retrieved NO2 slant columns show good consistency with the Quality Assurance for Essential Climate Variables (QA4ECV) retrieval with a good overall quality. Second, the STRatospheric Estimation Algorithm from Mainz (STREAM), which was originally developed for the TROPOspheric Monitoring Instrument (TROPOMI) instrument, was optimised for GOME-2 measurements to determine the stratospheric NO2 column density. Applied to synthetic GOME-2 data, the estimated stratospheric NO2 columns from STREAM shows good agreement with the a priori truth. An improved latitudinal correction is introduced in STREAM to reduce the biases over the subtropics. Applied to GOME-2 measurements, STREAM largely reduces the overestimation of stratospheric NO2 columns over polluted regions in the GDP 4.8 dataset. Third, the calculation of AMF applies an updated box-air-mass factor (box-AMF) look-up table (LUT) calculated using the latest version 2.7 of the Vector-LInearized Discrete Ordinate Radiative Transfer (VLIDORT) model with an increased number of reference points and vertical layers, a new GOME-2 surface albedo climatology, and improved a priori NO2 profiles obtained from the TM5-MP chemistry transport model. A large effect (mainly enhancement in summer and reduction in winter) on the retrieved tropospheric NO2 columns by more than 10 % is found over polluted regions. To evaluate the GOME-2 tropospheric NO2 columns, an end-to-end validation is performed using ground-based multiple-axis DOAS (MAXDOAS) measurements. The validation is illustrated for six stations covering urban, suburban, and background situations. Compared to the GDP 4.8 product, the new dataset presents improved agreement with the MAXDOAS measurements for all the stations.

scholarly journals An Improved Total and Tropospheric NO<sub>2</sub> Column Retrieval for GOME-2

2018 ◽  
Author(s):  
Song Liu ◽  
Pieter Valks ◽  
Gaia Pinardi ◽  
Isabelle De Smedt ◽  
Huan Yu ◽  
...  
Keyword(s):  
Cross Sections ◽  
Column Density ◽  
Transport Model ◽  
A Priori ◽  
Estimation Algorithm ◽  
Reference Points ◽  
Atmospheric Composition ◽  
Optical Absorption Spectroscopy ◽  
Cloud Parameters ◽  
Tropospheric No2

Abstract. An improved algorithm for the retrieval of total and tropospheric nitrogen dioxide (NO2) columns from the Global Ozone Monitoring Experiment-2 (GOME-2) is presented. The refined retrieval will be implemented in a future version of the GOME Data Processor (GDP) as used by the EUMETSAT Satellite Application Facility on Atmospheric Composition and UV Radiation (AC-SAF). The first main improvement is the application of an extended 425–497 nm wavelength fitting window in the differential optical absorption spectroscopy (DOAS) retrieval of the NO2 slant column density. Updated absorption cross-sections and a linear offset correction are used for the large fitting window. An improved slit function treatment is applied to compensate for both long-term and in-orbit drift of the GOME-2 slit function. Compared to the current operational (GDP 4.8) dataset, the use of these new features increases the NO2 columns by  1–3 × 1014 molec/cm2 and reduces the slant column error by ∼ 24 %. In addition, the bias between GOME-2A and GOME-2B measurements is largely reduced by adopting a new level 1b data version in the DOAS retrieval. The retrieved NO2 slant columns show good consistency with the Quality Assurance for Essential Climate Variables (QA4ECV) retrieval with a good overall quality. Second, the STRatospheric Estimation Algorithm from Mainz (STREAM), which was originally developed for the TROPOspheric Monitoring Instrument (TROPOMI) instrument, was optimized for GOME-2 measurements to determine the stratospheric NO2 column density. Applied to synthetic GOME-2 data, the estimated stratospheric NO2 columns from STREAM shows a good agreement with the a priori truth. An improved latitudinal correction is introduced in STREAM to reduce the biases over the subtropics. Applied to GOME-2 measurements, STREAM largely reduces the overestimation of stratospheric NO2 columns over polluted regions in the GDP 4.8 dataset. Third, the calculation of AMF applies an updated box-air mass factor (box-AMF) look-up table (LUT) calculated using the latest version of VLIDORT model with an increased number of reference points and vertical layers, a new GOME-2 surface albedo climatology, improved a priori NO2 profiles obtained from the TM5-MP chemistry transport model, and improved GOME-2 cloud parameters. A large effect on the retrieved tropospheric NO2 columns (more than 10 %) is found over polluted regions. To evaluate the GOME-2 tropospheric NO2 columns, an end-to-end validation is performed using ground-based multiple-axis DOAS (MAXDOAS) measurements. The validation is illustrated for 6 stations covering urban, suburban, and background situations. Compared to the GDP 4.8 product, the new dataset presents an improved agreement with the MAXDOAS measurements for all the stations.

Données LiDAR aériennes: pertinence de l'interprétation visuelle pour la foresterie

2017 ◽  
Vol 168 (3) ◽  
pp. 127-133
Author(s):  
Matthew Parkan
Keyword(s):  
Cross Sections ◽  
Forest Edge ◽  
Airborne Lidar ◽  
Visual Interpretation ◽  
Individual Tree ◽  
Small Areas ◽  
Interactive 3D ◽  
The Individual ◽  
Airborne Lidar Data ◽  
Stem Position

Airborne LiDAR data: relevance of visual interpretation for forestry Airborne LiDAR surveys are particularly well adapted to map, study and manage large forest extents. Products derived from this technology are increasingly used by managers to establish a general diagnosis of the condition of forests. Less common is the use of these products to conduct detailed analyses on small areas; for example creating detailed reference maps like inventories or timber marking to support field operations. In this context, the use of direct visual interpretation is interesting, because it is much easier to implement than automatic algorithms and allows a quick and reliable identification of zonal (e.g. forest edge, deciduous/persistent ratio), structural (stratification) and point (e.g. tree/stem position and height) features. This article examines three important points which determine the relevance of visual interpretation: acquisition parameters, interactive representation and identification of forest characteristics. It is shown that the use of thematic color maps within interactive 3D point cloud and/or cross-sections makes it possible to establish (for all strata) detailed and accurate maps of a parcel at the individual tree scale.

scholarly journals The Reaction of Spin–Orbit State-Selected Ca(PJ03) With CH3I, CH2I2, and SF6

1986 ◽  
Vol 6 (6) ◽  
pp. 391-402 ◽  
Author(s):  
Mark L. Campbell ◽  
Nick Furio ◽  
Paul J. Dagdigian
Keyword(s):  
Chemical Reactions ◽  
Cross Sections ◽  
Optical Pumping ◽  
Spin Orbit ◽  
Alkyl Bromide ◽  
The Individual ◽  
State Selection

Chemiluminescence cross sections for reaction of the individual spin–orbit states of metastable Ca(PJ03) with CH3I, CH2I2, and SF6 have been determined by the use of optical pumping state selection. This technique was also used to separate the chemiluminescence arising from the two excited metastable Ca 3P0 and 1D states. The spin–orbit dependence of the chemiluminescence pathway was found to be substantial for the CH3I and CH2I2 reactions and similar to that previously observed for halogen diatom and alkyl bromide reagents. By contrast, no spin–orbit effect was observed for Ca(3P0)+SF6. These results are discussed in terms of our previously presented model for the origin of spin–orbit effects in chemical reactions.

scholarly journals Communities and the individual: Beyond the liberal–communitarian divide

2021 ◽  
Vol 47 (4) ◽  
pp. 392-401
Author(s):  
Volker Kaul
Keyword(s):  
Personal Autonomy ◽  
A Priori ◽  
Significant Others ◽  
The Self ◽  
Global Perspective ◽  
Self And Identity ◽  
Default Position ◽  
The Individual

Liberalism believes that individuals are endowed a priori with reason or at least agency and it is up to that reason and agency to make choices, commitments and so on. Communitarianism criticizes liberalism’s explicit and deliberate neglect of the self and insists that we attain a self and identity only through the effective recognition of significant others. However, personal autonomy does not seem to be a default position, neither reason nor community is going to provide it inevitably. Therefore, it is so important to go beyond the liberal–communitarian divide. This article is analysing various proposals in this direction, asks about the place of communities and the individual in times of populism and the pandemic and provides a global perspective on the liberal–communitarian debate.

Survey Data Quality in Analyzing Harmonized Indicators of Protest Behavior: A Survey Data Recycling Approach

2021 ◽  
pp. 000276422110216
Author(s):  
Kazimierz M. Slomczynski ◽  
Irina Tomescu-Dubrow ◽  
Ilona Wysmulek
Keyword(s):  
Data Processing ◽  
Data Quality ◽  
Survey Data ◽  
A Priori ◽  
Data Sets ◽  
New Approach ◽  
Survey Quality ◽  
Survey Error ◽  
Ex Post ◽  
The Impact

This article proposes a new approach to analyze protest participation measured in surveys of uneven quality. Because single international survey projects cover only a fraction of the world’s nations in specific periods, researchers increasingly turn to ex-post harmonization of different survey data sets not a priori designed as comparable. However, very few scholars systematically examine the impact of the survey data quality on substantive results. We argue that the variation in source data, especially deviations from standards of survey documentation, data processing, and computer files—proposed by methodologists of Total Survey Error, Survey Quality Monitoring, and Fitness for Intended Use—is important for analyzing protest behavior. In particular, we apply the Survey Data Recycling framework to investigate the extent to which indicators of attending demonstrations and signing petitions in 1,184 national survey projects are associated with measures of data quality, controlling for variability in the questionnaire items. We demonstrate that the null hypothesis of no impact of measures of survey quality on indicators of protest participation must be rejected. Measures of survey documentation, data processing, and computer records, taken together, explain over 5% of the intersurvey variance in the proportions of the populations attending demonstrations or signing petitions.

Sign in / Sign up

Export Citation Format

Share Document