scholarly journals The CALIPSO Lidar Cloud and Aerosol Discrimination: Version 2 Algorithm and Initial Assessment of Performance

2009 ◽  
Vol 26 (7) ◽  
pp. 1198-1213 ◽  
Author(s):  
Zhaoyan Liu ◽  
Mark Vaughan ◽  
David Winker ◽  
Chieko Kittaka ◽  
Brian Getzewich ◽  
...  
Keyword(s):  
Current Data ◽  
Initial Assessment ◽  
Aerosol Layer ◽  
Polar Regions ◽  
Source Regions ◽  
Data Release ◽  
Future Data ◽  
Full Day ◽  
Manual Classification ◽  
Correct Discrimination

Abstract The Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite was launched in April 2006 to provide global vertically resolved measurements of clouds and aerosols. Correct discrimination between clouds and aerosols observed by the lidar aboard the CALIPSO satellite is critical for accurate retrievals of cloud and aerosol optical properties and the correct interpretation of measurements. This paper reviews the theoretical basis of the CALIPSO lidar cloud and aerosol discrimination (CAD) algorithm, and describes the enhancements made to the version 2 algorithm that is used in the current data release (release 2). The paper also presents a preliminary assessment of the CAD performance based on one full day (12 August 2006) of expert manual classification and on one full month (July 2006) of the CALIOP 5-km cloud and aerosol layer products. Overall, the CAD algorithm works well in most cases. The 1-day manual verification suggests that the success rate is in the neighborhood of 90% or better. Nevertheless, several specific layer types are still misclassified with some frequency. Among these, the most prevalent are dense dust and smoke close to the source regions. The analysis of the July 2006 data showed that the misclassification of dust as cloud occurs for <1% of the total tropospheric cloud and aerosol features found. Smoke layers are misclassified less frequently than are dust layers. Optically thin clouds in the polar regions can be misclassified as aerosols. While the fraction of such misclassifications is small compared with the number of aerosol features found globally, caution should be taken when studies are performed on the aerosol in the polar regions. Modifications will be made to the CAD algorithm in future data releases, and the misclassifications encountered in the current data release are expected to be reduced greatly.

scholarly journals CALIPSO level 3 stratospheric aerosol profile product: version 1.00 algorithm description and initial assessment

2019 ◽  
Vol 12 (11) ◽  
pp. 6173-6191 ◽  
Author(s):  
Jayanta Kar ◽  
Kam-Pui Lee ◽  
Mark A. Vaughan ◽  
Jason L. Tackett ◽  
Charles R. Trepte ◽  
...  
Keyword(s):  
Space Station ◽  
Volcanic Eruptions ◽  
Satellite Observation ◽  
Stratospheric Aerosol ◽  
Initial Assessment ◽  
Orthogonal Polarization ◽  
Aerosol Layer ◽  
Stratospheric Dynamics ◽  
Level 3 ◽  
Lidar Ratio

Abstract. In August 2018, the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) project released a new level 3 stratospheric aerosol profile data product derived from nearly 12 years of measurements acquired by the spaceborne Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP). This monthly averaged, gridded level 3 product is based on version 4 of the CALIOP level 1B and level 2 data products, which feature significantly improved calibration that now makes it possible to reliably retrieve profiles of stratospheric aerosol extinction and backscatter coefficients at 532 nm. This paper describes the science algorithm and data handling techniques that were developed to generate the CALIPSO version 1.00 level 3 stratospheric aerosol profile product. Further, we show that the extinction profiles (retrieved using a constant lidar ratio of 50 sr) capture the major stratospheric perturbations in both hemispheres over the last decade resulting from volcanic eruptions, extreme smoke events, and signatures of stratospheric dynamics. Initial assessment of the product by intercomparison with the stratospheric aerosol retrievals from the Stratospheric Aerosol and Gas Experiment III (SAGE III) on the International Space Station (ISS) indicates good agreement in the tropical stratospheric aerosol layer (30∘ N–30∘ S), where the average difference between zonal mean extinction profiles is typically less than 25 % between 20 and 30 km (CALIPSO biased high). However, differences can exceed 100 % in the very low aerosol loading regimes found above 25 km at higher latitudes. Similarly, there are large differences (≥100 %) within 2 to 3 km above the tropopause that might be due to cloud contamination issues.

scholarly journals Strong variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills

2020 ◽  
Author(s):  
Sreeharsha Hanumanthu ◽  
Bärbel Vogel ◽  
Rolf Müller ◽  
Simone Brunamonti ◽  
Suvarna Fadnavis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Aerosol Layer ◽  
South Asian Summer Monsoon ◽  
Air Masses ◽  
Source Regions ◽  
Himalayan Foothills ◽  
Asian Summer ◽  
Aerosol Backscatter

Abstract. The South Asian summer monsoon is associated with a large-scale anticyclonic circulation in the Upper Troposphere and Lower Stratosphere (UTLS), which confines the air mass inside. During boreal summer, the confinement of this air mass leads to an accumulation of aerosol between about 13 km and 18 km (360 K and 440 K potential temperature), this accumulation of aerosol constitutes the Asian Tropopause Aerosol Layer (ATAL). We present balloon-borne aerosol backscatter measurements of the ATAL performed by the Compact Optical Backscatter Aerosol Detector (COBALD) instrument in Nainital in Northern India in August 2016, and compare these with COBALD measurements in the post-monsoon time in November 2016. The measurements demonstrate a strong variability of the ATAL's altitude, vertical extent, aerosol backscatter intensity and cirrus cloud occurrence frequency. Such a variability cannot be deduced from climatological means of the ATAL as they are derived from satellite measurements. To explain this observed variability we performed a Lagrangian back-trajectory analysis using the Chemical Lagrangian Model of the Stratosphere (CLaMS). We identify the transport pathways of air parcels contributing to the ATAL over Nainital in August 2016, as well as the source regions of the air masses contributing to the composition of the ATAL. Our analysis reveals a variety of factors contributing to the observed day-to-day variability of the ATAL: continental convection, tropical cyclones (maritime convection), dynamics of the anticyclone and stratospheric intrusions. Thus, the ATAL is a mixture of air masses coming from different atmospheric height layers. In addition, contributions from the model boundary layer originate in different geographic source regions. The location of strongest updraft along the backward trajectories reveal a cluster of strong upward transport at the southern edge of the Himalayan foothills. From the top of the convective outflow level (about 13 km; 360 K) the air parcels ascend slowly to ATAL altitudes within a large-scale upward spiral driven by the diabatic heating in the anticyclonic flow of the South Asian summer monsoon at UTLS altitudes. Cases with a strong ATAL typically show boundary layer contributions from the Tibetan Plateau, the foothills of the Himalayas and other continental regions below the Asian monsoon. Weaker ATAL cases show higher contributions from the maritime boundary layer, often related to tropical cyclones, indicating a mixing of unpolluted and polluted air masses. Because of the strong growth of Asian economies, increasing anthropogenic emissions in the future are expected to enhance the thickness and intensity of the ATAL, thereby also enhancing the global stratospheric aerosol loading, which likely impacts surface climate.

The RAdial Velocity Experiment: preparing the 6th Data Release chemical abundances with GAUGUIN

2017 ◽  
Vol 13 (S334) ◽  
pp. 302-303
Author(s):  
Guillaume Guiglion ◽  
Keyword(s):  
Radial Velocity ◽  
Milky Way ◽  
Chemical Elements ◽  
Elemental Abundance ◽  
Atmospheric Parameters ◽  
Chemical Abundances ◽  
Abundance Patterns ◽  
Medium Resolution ◽  
Data Release ◽  
Future Data

AbstractIn the context of the Radial Velocity Experiment (RAVE, Steinmetz et al. 2006), we present chemical abundances derived with the pipeline GAUGUIN. Based of 520 701 RAVE stars with medium resolution (R~7 500) spectra and stellar atmospheric parameters of the fifth Data Release, the analysis is performed around the infrared Ca-triple domain for 6 chemical elements: Mg, Ni, Si, Ti, Fe and Al. We discuss here the reliability of the chemical abundances provided by GAUGUIN, and the implications for the future Data Release 6 of the RAVE Survey. We also present elemental abundance patterns of Milky Way components based of kinematical criteria.

Exploring for the Future: data release of whole-rock Re–Os from the South Nicholson region, Northern Territory and Queensland

2020 ◽  
Author(s):  
J.R. Anderson ◽  
A.J.M. Jarrett ◽  
C.J. Boreham ◽  
D.C. Champion ◽  
D. Huston ◽  
...  
Keyword(s):  
Northern Territory ◽  
The South ◽  
Data Release ◽  
The Future ◽  
Future Data

scholarly journals G-Band Period-Luminosity Relation For Galactic Cepheids Based on Gaia DR1 Measurements

2017 ◽  
Vol 12 (S330) ◽  
pp. 337-338
Author(s):  
Chow-Choong Ngeow ◽  
Anupam Bhardwaj ◽  
Shashi M. Kanbur
Keyword(s):  
Bayesian Analysis ◽  
Gaia Dr1 ◽  
Classical Cepheids ◽  
Standard Candle ◽  
Data Release ◽  
Future Data

AbstractClassical Cepheids (hereafter Cepheids) are important standard candle as they obey the famous period-luminosity (PL) relation. Parallax measurements from Gaia offer a unique opportunity to derive or calibrate the PL relations for Galactic Cepheids, as traditionally their distances were measured via different methods. In this work, we attempted to derive the Gaia G-band PL relation based on the Gaia Data Release 1 (DR1) measurements. We adopted the inferred distances provided by Astraatmadja & Bailer-Jones (2016), calculated using two priors in a Bayesian analysis, and cross-matched to known Galactic Cepheids. The resulting G-band PL relation, however, exhibits a much larger scatter than expected. Hence the inferred distances based on the Gaia DR1 parallaxes are not suitable for calibrating the Galactic PL relation, and future Data Releases with improved parallax measurements are desirable.

scholarly journals Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills

2020 ◽  
Vol 20 (22) ◽  
pp. 14273-14302
Author(s):  
Sreeharsha Hanumanthu ◽  
Bärbel Vogel ◽  
Rolf Müller ◽  
Simone Brunamonti ◽  
Suvarna Fadnavis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Anthropogenic Emissions ◽  
Aerosol Layer ◽  
South Asian Summer Monsoon ◽  
Source Regions ◽  
Himalayan Foothills ◽  
Asian Summer ◽  
Aerosol Backscatter

Abstract. The South Asian summer monsoon is associated with a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS), which confines the air mass inside. During boreal summer, the confinement of this air mass leads to an accumulation of aerosol between about 13 and 18 km (360 and 440 K potential temperature); this accumulation of aerosol constitutes the Asian Tropopause Aerosol Layer (ATAL). We present balloon-borne aerosol backscatter measurements of the ATAL performed by the Compact Optical Backscatter Aerosol Detector (COBALD) instrument in Nainital in northern India in August 2016, and compare these with COBALD measurements in the post-monsoon time in November 2016. The measurements demonstrate a strong variability of the ATAL's altitude, vertical extent, aerosol backscatter intensity and cirrus cloud occurrence frequency. Such a variability cannot be deduced from climatological means of the ATAL as they are derived from satellite measurements. To explain this observed variability we performed a Lagrangian back-trajectory analysis using the Chemical Lagrangian Model of the Stratosphere (CLaMS). We identify the transport pathways as well as the source regions of air parcels contributing to the ATAL over Nainital in August 2016. Our analysis reveals a variety of factors contributing to the observed day-to-day variability of the ATAL: continental convection, tropical cyclones (maritime convection), dynamics of the anticyclone and stratospheric intrusions. Thus, the air in the ATAL is a mixture of air masses coming from different atmospheric altitude layers. In addition, contributions from the model boundary layer originate in different geographic source regions. The location of the strongest updraft along the backward trajectories reveals a cluster of strong upward transport at the southern edge of the Himalayan foothills. From the top of the convective outflow level (about 13 km; 360 K) the air parcels ascend slowly to ATAL altitudes within a large-scale upward spiral driven by the diabatic heating in the anticyclonic flow of the South Asian summer monsoon at UTLS altitudes. Cases with a strong ATAL typically show boundary layer contributions from the Tibetan Plateau, the foothills of the Himalayas and other continental regions below the Asian monsoon. Weaker ATAL cases show higher contributions from the maritime boundary layer, often related to tropical cyclones, indicating a mixing of clean maritime and polluted continental air. On the one hand increasing anthropogenic emissions in the future are expected due to the strong growth of Asian economies; on the other hand the implementation of new emission control measures (in particular in China) has reduced the anthropogenic emissions of some pollutants contributing to the ATAL substantially. It needs to be monitored in the future whether the thickness and intensity of the ATAL will further increase, which will likely impact the surface climate.

scholarly journals Storm enhanced density: magnetic conjugacy effects

2007 ◽  
Vol 25 (8) ◽  
pp. 1791-1799 ◽  
Author(s):  
J. C. Foster ◽  
W. Rideout
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Ionospheric Disturbance ◽  
Polar Regions ◽  
The North ◽  
Polar Caps ◽  
Source Regions ◽  
Field Lines ◽  
Magnetic Conjugacy ◽  
Early Phases

Abstract. In the early phases of a geomagnetic storm, the low and mid-latitude ionosphere are greatly perturbed. Large SAPS electric fields map earthward from the perturbed ring current overlapping and eroding the outer plasmasphere and mid-latitude ionosphere, drawing out extended plumes of storm enhanced density (SED). We use combined satellite and ground-based observations to investigate the degree of magnetic conjugacy associated with specific features of the stormtime ionospheric perturbation. We find that many ionospheric disturbance features exhibit degrees of magnetic conjugacy and simultaneity which implicate the workings of electric fields. TEC enhancements on inner-magnetospheric field lines at the base of the SED plumes exhibit localized and longitude-dependent features which are not strictly magnetic conjugate. The SED plumes streaming away from these source regions closely follow magnetic conjugate paths. SED plumes can be used as a tracer of the location and strength of disturbance electric fields. The SED streams of cold plasma from lower latitudes enter the polar caps near noon, forming conjugate tongues of ionization over the polar regions. SED plumes exhibit close magnetic conjugacy, confirming that SED is a convection electric field dominated effect. Several conclusions are reached: 1) The SED plume occurs in magnetically-conjugate regions in both hemispheres. 2) The position of the sharp poleward edge of the SED plume is closely conjugate. 3) The SAPS electric field is observed in magnetically conjugate regions (SAPS channel). 4) The strong TEC enhancement at the base of the SED plume in the north American sector is more extensive than in its magnetic conjugate region. 5) The entry of the SED plume into the polar cap near noon, forming the polar tongue of ionization (TOI), is seen in both hemispheres in magnetically-conjugate regions.

scholarly journals CALIPSO Level 3 Stratospheric Aerosol Product: Version 1.00 Algorithm Description and Initial Assessment

2019 ◽  
Author(s):  
Jayanta Kar ◽  
Kam-Pui Lee ◽  
Mark A. Vaughan ◽  
Jason L. Tackett ◽  
Charles R. Trepte ◽  
...  
Keyword(s):  
Space Station ◽  
Volcanic Eruptions ◽  
Satellite Observation ◽  
Stratospheric Aerosol ◽  
Initial Assessment ◽  
Orthogonal Polarization ◽  
Aerosol Layer ◽  
Stratospheric Dynamics ◽  
Level 3 ◽  
Good Agreement

Abstract. In August 2018, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) project released a new level 3 stratospheric aerosol profile data product derived from nearly 12 years of measurements acquired by the space-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). This monthly averaged, gridded level 3 product is based on version 4.2 of the CALIOP level 1 and level 2 data products, which feature significantly improved calibration that now makes it possible to reliably retrieve profiles of stratospheric aerosol extinction and backscatter coefficients. This paper describes the science algorithm and data handling techniques that were developed to generate the CALIPSO version 1.00 level 3 stratospheric aerosol profile product. Further, we show that the retrieved extinction profiles capture the major stratospheric perturbations over the last decade resulting from volcanic eruptions, extreme smoke events, and signatures of stratospheric dynamics. Initial assessment of the product by inter-comparison with the stratospheric aerosol retrievals from the Stratospheric Aerosol and Gas Experiment III (SAGE III) on the International Space Station (ISS) indicates good agreement in the tropical stratospheric aerosol layer (30° N–30° S), where the average difference between zonal mean extinction profiles is typically less than 25 % between 20 km and 30 km. However, differences can exceed 100 % in the very low aerosol loading regimes found above 25 km at higher latitudes.

Managing Temporal Data

2009 ◽  
pp. 28-36 ◽  
Author(s):  
Abdullah Uz Tansel
Keyword(s):  
Relational Databases ◽  
Handling Time ◽  
Current Data ◽  
Temporal Databases ◽  
Time Varying ◽  
Temporal Data ◽  
Temporal Database ◽  
Organizational Intelligence ◽  
Relational Data Model ◽  
Future Data

In general, databases store current data. However,the capability to maintain temporal data is a crucial requirement for many organizations and provides the base for organizational intelligence. A temporal database maintains time-varying data, that is, past, present, and future data. In this chapter, we focus on the relational data model and address the subtle issues in modeling and designing temporal databases. A common approach to handle temporal data within the traditional relational databases is the addition of time columns to a relation. Though this appears to be a simple and intuitive solution, it does not address many subtle issues peculiar to temporal data, that is, comparing database states at two different time points, capturing the periods for concurrent events and accessing times beyond these periods, handling multi-valued attributes, coalescing and restructuring temporal data, and so forth, [Gadia 1988, Tansel and Tin 1997]. There is a growing interest in temporal databases. A first book dedicated to temporal databases [Tansel at al 1993] followed by others addressing issues in handling time-varying data [Betini, Jajodia and Wang 1988, Date, Darwen and Lorentzos 2002, Snodgrass 1999].

scholarly journals Addressing the importance of microplastic particles as vectors for long-range transport of chemical contaminants: perspective in relation to prioritizing research and regulatory actions

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Todd Gouin
Keyword(s):  
Physicochemical Properties ◽  
Long Range ◽  
Environmental Fate ◽  
Polar Regions ◽  
Chemical Contaminants ◽  
Toxicological Effects ◽  
Atmospheric Particulates ◽  
Source Regions ◽  
Global Transport ◽  
Range Transport

AbstractOver the last several years there has been increasing concern regarding the environmental fate and potential global transport of plastic debris, particularly in the form of microplastic particles (MPs). The global transport of MPs has also triggered concerns regarding the potential role that its mobility may represent towards influencing the long-range environmental transport (LRET) of particle-bound chemicals, particularly the large number of chemicals known to be added to plastic. This perspective considers the various lines-of-evidence that might be used towards understanding the LRET of persistent organic pollutants (POPs). For instance, it has been proposed that the LRET of POPs is facilitated by global fractionation processes that facilitate the mobility of chemicals from source regions towards remote locations, such as the polar regions, where they have the potential to accumulate. These processes are influenced by the physicochemical properties of POPs and can result in various transport mechanisms influencing environmental fate and transport. Here I suggest that there are similarities that can be drawn, whereby knowledge of how differences in the physicochemical properties of MPs relative to different emission scenarios, can influence the relative importance of sequestration processes that may result in global fractionation of MPs. Several challenges are identified throughout the perspective, with an urgent need towards the development and application of standard sampling and analytical methods being identified as critical for enabling datasets to be reliably compared for use in better understanding potential source-receptor relationships, as well as advancing the characterization and quantification of various environmental fate processes. In many instances, it is suggested that advances in our understanding can be facilitated based on knowledge obtained in other areas of research, such as in relation to studies developing tools to evaluate the mobility of particulate organic matter in aqueous environments or from studies investigating the fate and mobility of atmospheric particulates. Recognizing that not all MPs are equal, with respect to environmental fate and toxicological effects, knowledge regarding which types of MPs are likely to be subject to LRET can only strengthen our ability to evaluate their role as vectors of transport for plastic associated chemicals and the associated risks that their LRET may represent. Nevertheless, several outstanding issues remain that would benefit from constructive discussions between all stakeholders. It is anticipated that this perspective can play a role in initiating those discussions.

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