scholarly journals Comparison of cloud statistics from spaceborne lidar systems

2008 ◽  
Vol 8 (23) ◽  
pp. 6965-6977 ◽  
Author(s):  
S. Berthier ◽  
P. Chazette ◽  
J. Pelon ◽  
B. Baum
Keyword(s):  
Signal To Noise Ratio ◽  
Simple Algorithm ◽  
Middle Latitude ◽  
Global Scale ◽  
Orthogonal Polarization ◽  
Space Technology ◽  
Laser Altimeter ◽  
Vertical Column ◽  
Inter Tropical Convergence Zone ◽  
Stratospheric Clouds

Abstract. The distribution of clouds in a vertical column is assessed on the global scale through analysis of lidar measurements obtained from three spaceborne lidar systems: LITE (Lidar In-space Technology Experiment, NASA), GLAS (Geoscience Laser Altimeter System, NASA), and CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization). Cloud top height (CTH) is obtained from the LITE profiles based on a simple algorithm that accounts for multilayer cloud structures. The resulting CTH results are compared to those obtained by the operational algorithms of the GLAS and CALIOP instruments. Based on our method, spaceborne lidar data are analyzed to establish statistics on the cloud top height. The resulting columnar results are used to investigate the inter-annual variability in the lidar cloud top heights. Statistical analyses are performed for a range of CTH (high, middle, low) and latitudes (polar, middle latitude and tropical). Probability density functions of CTH are developed. Comparisons of CTH developed from LITE, for 2 weeks of data in 1994, with ISCCP (International Satellite Cloud Climatology Project) cloud products show that the cloud fraction observed from spaceborne lidar is much higher than that from ISCCP. Another key result is that ISCCP products tend to underestimate the CTH of optically thin cirrus clouds. Significant differences are observed between LITE-derived cirrus CTH and both GLAS and CALIOP-derived cirrus CTH. Such a difference is due primarily to the lidar signal-to-noise ratio that is approximately a factor of 3 larger for the LITE system than for the other lidars. A statistical analysis for a full year of data highlights the influence of both the Inter-Tropical Convergence Zone and polar stratospheric clouds.

scholarly journals Comparison of cloud statistics from spaceborne lidar systems

2008 ◽  
Vol 8 (2) ◽  
pp. 5269-5304 ◽  
Author(s):  
S. Berthier ◽  
P. Chazette ◽  
J. Pelon ◽  
B. Baum
Keyword(s):  
Simple Algorithm ◽  
Middle Latitude ◽  
Global Scale ◽  
Orthogonal Polarization ◽  
Space Technology ◽  
Laser Altimeter ◽  
Vertical Column ◽  
Signal Ratio ◽  
Inter Tropical Convergence Zone ◽  
Stratospheric Clouds

Abstract. The distribution of clouds in a vertical column is assessed on the global scale through analysis of lidar measurements obtained from three spaceborne lidar systems: LITE (Lidar In-space Technology Experiment, NASA), GLAS (Geoscience Laser Altimeter System, NASA), and CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization). Cloud top height (CTH) is obtained from the LITE profiles based on a simple algorithm that accounts for multilayer cloud structures. The resulting CTH results are compared to those obtained by the operational algorithms of the GLAS and CALIOP instruments. Based on our method, spaceborne lidar data are analyzed to establish statistics on the cloud top height. The resulting columnar results are used to investigate the inter-annual variability in the lidar cloud top heights. Statistical analyses are performed for a range of CTH (high, middle, low) and latitudes (polar, middle latitude and tropical). Probability density functions of CTH are developed. Comparisons of CTH developed from LITE, for 2 weeks of data in 1994, with ISCCP (International Satellite Cloud Climatology Project) cloud products show that the cloud fraction observed from spaceborne lidar is much higher than that from ISCCP. Another key result is that ISCCP products tend to underestimate the CTH of optically thin cirrus clouds. Significant differences are observed between LITE-derived cirrus CTH and both GLAS and CALIOP-derived cirrus CTH. Such a difference is due primarily to the lidar signal ratio that is larger than a factor of approximately 3 for the LITE system. A statistical analysis for a full year of data highlights the influence of both the Inter-Tropical Convergence Zone and polar stratospheric clouds.

On the best locations for ground-based PSC observations

2021 ◽  
Author(s):  
Matthias Tesche ◽  
Peggy Achtert ◽  
Michael Pitts
Keyword(s):  
Signal To Noise Ratio ◽  
The Arctic ◽  
Orthogonal Polarization ◽  
Microphysical Properties ◽  
Inhibiting Factors ◽  
Comprehensive Picture ◽  
Ground Based Lidar ◽  
Stratospheric Clouds ◽  
The Antarctic ◽  
Lidar Observations

<p>Spaceborne observations of Polar Stratospheric Clouds (PSCs) with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provide a comprehensive picture of the occurrence of Arctic and Antarctic PSCs as well as their microphysical properties. However, advances in understanding PSC microphysics also require measurements with ground-based instruments, which are often superior to CALIOP in terms of, e.g. time resolution, measured parameters, and signal-to-noise ratio. This advantage is balanced by the location of ground-based PSC observations and their dependence on tropospheric cloudiness. CALIPSO observations during the boreal winters from December 2006 to February 2018 and the austral winters 2012 and 2015 are used to assess the effect of tropospheric cloudiness and other measurement-inhibiting factors on the representativeness of ground-based PSC observations with lidar in the Arctic and Antarctic, respectively. Information on tropospheric and stratospheric clouds from the CALIPSO Cloud Profile product (05kmCPro version 4.10) and the PSC mask version 2, respectively, is combined on a profile-by-profile basis to identify conditions under which a ground-based lidar is likely to perform useful measurements for the analysis of PSC occurrence. It is found that the location of a ground-based measurement together with the related tropospheric cloudiness can have a profound impact on the derived PSC statistics and that these findings are rarely in agreement with polar-wide results from CALIOP observations. Considering the current polar research infrastructure, it is concluded that the most suitable sites for the expansion of capabilities for ground-based lidar observations of PSCs are Summit and Villum in the Arctic and Mawson, Troll, and Vostok in the Antarctic.</p>

scholarly journals Location controls the findings of ground-based PSC observations

2020 ◽  
Author(s):  
Matthias Tesche ◽  
Peggy Achtert ◽  
Michael C. Pitts
Keyword(s):  
Signal To Noise Ratio ◽  
The Arctic ◽  
Orthogonal Polarization ◽  
Microphysical Properties ◽  
Polar Stratospheric Cloud ◽  
Comprehensive Picture ◽  
Ground Based Lidar ◽  
Stratospheric Clouds ◽  
The Antarctic ◽  
Lidar Observations

Abstract. Spaceborne observations of Polar Stratospheric Clouds (PSCs) with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provide a comprehensive picture of the occurrence of Arctic and Antarctic PSCs as well as their microphysical properties. However, advances in understanding PSC microphysics also require measurements with ground-based instruments, which are often superior to CALIOP in terms of, e.g. time resolution, measured parameters, and signal-to-noise ratio. This advantage is balanced by the location of ground-based PSC observations and their dependence on tropospheric cloudiness. CALIPSO observations during the boreal winters from December 2006 to February 2018 and the austral winters 2012 and 2015 are used to assess the representativeness of ground-based PSC observations with lidar in the Arctic and Antarctic, respectively. Information on tropospheric and stratospheric clouds from the CALIPSO Cloud Profile product (05kmCPro version 4.10) and the Polar Stratospheric Cloud (PSC) mask version 2, respectively, is combined on a profile-by-profile basis to identify conditions under which a ground-based lidar is likely to perform useful measurements for the analysis of PSC occurrence. It is found that the location of a ground-based measurement together with the related tropospheric cloudiness can have a profound impact on the derived PSC statistics and that these findings are rarely in agreement with polar-wide results from CALIOP observations. Considering the current polar research infrastructure, it is concluded that the most suitable sites for the expansion of capabilities for ground-based lidar observations of PSCs are Summit and Villum in the Arctic and Concordia, Troll, and Vostok in the Antarctic.

scholarly journals On the best locations for ground-based polar stratospheric cloud (PSC) observations

2021 ◽  
Vol 21 (1) ◽  
pp. 505-516 ◽  
Author(s):  
Matthias Tesche ◽  
Peggy Achtert ◽  
Michael C. Pitts
Keyword(s):  
Signal To Noise Ratio ◽  
The Arctic ◽  
Orthogonal Polarization ◽  
Microphysical Properties ◽  
Polar Stratospheric Cloud ◽  
Comprehensive Picture ◽  
Ground Based Lidar ◽  
Stratospheric Clouds ◽  
Cloud Mask ◽  
The Antarctic

Abstract. Spaceborne observations of polar stratospheric clouds (PSCs) with the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provide a comprehensive picture of the occurrence of Arctic and Antarctic PSCs as well as their microphysical properties. However, advances in understanding PSC microphysics also require measurements with ground-based instruments, which are often superior to CALIOP in terms of, for example, time resolution, measured parameters, and signal-to-noise ratio. This advantage is balanced by the location of ground-based PSC observations and their dependence on tropospheric cloudiness. CALIPSO observations during the boreal winters from December 2006 to February 2018 and the austral winters 2012 and 2015 are used to assess the effect of tropospheric cloudiness and other measurement-inhibiting factors on the representativeness of ground-based PSC observations with lidar in the Arctic and Antarctic, respectively. Information on tropospheric and stratospheric clouds from the CALIPSO Cloud Profile product (05kmCPro version 4.10) and the CALIPSO polar stratospheric cloud mask version 2, respectively, is combined on a profile-by-profile basis to identify conditions under which a ground-based lidar is likely to perform useful measurements for the analysis of PSC occurrence. It is found that the location of a ground-based measurement together with the related tropospheric cloudiness can have a profound impact on the derived PSC statistics and that these findings are rarely in agreement with polewide results from CALIOP observations. Considering the current polar research infrastructure, it is concluded that the most suitable sites for the expansion of capabilities for ground-based lidar observations of PSCs are Summit and Villum in the Arctic and Mawson, Troll, and Vostok in the Antarctic.

Structured methods for improving flow measurement accuracy in pipelines

2020 ◽  
pp. 30-35
Author(s):  
Gurami N. Akhobadze
Keyword(s):  
Flow Measurement ◽  
Measurement Accuracy ◽  
Directional Coupler ◽  
Signal To Noise Ratio ◽  
Scattered Wave ◽  
Orthogonal Polarization ◽  
Flow Sensors ◽  
Information Signal ◽  
Mass Flows ◽  
Processing Device

In the age of digital transformation of production processes in industry and science the development and design of intelligent flow sensors for granular and liquid substances transferring through pipelines becomes more important. With this in view new approaches for improving the accuracy of microwave flowmeters are proposed. Taking into account the characteristics ofelectromagnetic waves propagating through a pipeline, a wave scattered by inhomogeneities of the controlled medium is analyzed. Features of the transformation of the polarized scattered wave limiting the geometric dimensions of the pipeline and optimizing the values of the useful scattered signal are revealed. Expediency of collection of the information signal with orthogonal polarization of the scattered wave and through a directional coupler is substantiated. The method of estimating the measurement accuracy with reference to the signal-to-noise ratio at the input of the processing device is given. The research results can be used in cryogenic machine engineering to measure volume and mass flows of liquid cryogenic products.

scholarly journals An assessment of cloud top thermodynamic phase products obtained from A-Train passive and active sensors

2013 ◽  
Vol 6 (5) ◽  
pp. 8371-8411 ◽  
Author(s):  
S. Zeng ◽  
J. Riedi ◽  
F. Parol ◽  
C. Cornet ◽  
F. Thieuleux
Keyword(s):  
General Circulation ◽  
Supercooled Liquid ◽  
General Circulation Models ◽  
Global Scale ◽  
Orthogonal Polarization ◽  
Liquid Droplets ◽  
High Confidence ◽  
Cloud Properties ◽  
Fractional Cloud ◽  
Thermodynamic Phase

Abstract. The A-Train observations provide an unprecedented opportunity for the production of high quality dataset describing cloud properties. We illustrate in this study the use of one year of coincident POLDER (Polarization and Directionality of the Earth Reflectance), MODIS (MODerate Resolution Imaging Spectroradiometer) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations to establish a reference dataset for the description of cloud top thermodynamic phase at global scale. We present the results of an extensive comparison between POLDER and MODIS cloud top phase products and discuss those in view of cloud vertical structure and optical properties derived simultaneously from collocated CALIOP active measurements. These results allow to identify and quantify potential biases present in the 3 considered dataset. Among those, we discuss the impacts of observation geometry, thin cirrus in multilayered and single layered cloud systems, supercooled liquid droplets, aerosols, fractional cloud cover and snow/ice or bright surfaces on global statistics of cloud phase derived from POLDER and MODIS passive measurements. Based on these analysis we define criteria for the selection of high confidence cloud phase retrievals which in turn can serve for the establishment of a reference cloud phase product. This high confidence joint product derived from POLDER/PARASOL and MODIS/Aqua can be used in the future as a benchmark for the evaluation of other cloud climatologies, for the assessment of cloud phase representation in models and the development of better cloud phase parametrization in the general circulation models (GCMs).

scholarly journals CALIPSO lidar calibration at 1064 nm: version 4 algorithm

2019 ◽  
Vol 12 (1) ◽  
pp. 51-82 ◽  
Author(s):  
Mark Vaughan ◽  
Anne Garnier ◽  
Damien Josset ◽  
Melody Avery ◽  
Kam-Pui Lee ◽  
...  
Keyword(s):  
Molecular Model ◽  
Signal To Noise Ratio ◽  
High Spectral Resolution ◽  
Orthogonal Polarization ◽  
Radiometric Calibration ◽  
Calibration Target ◽  
Full Account ◽  
High Spectral Resolution Lidar ◽  
532 Nm ◽  
Calibration Coefficients

Abstract. Radiometric calibration of space-based elastic backscatter lidars is accomplished by comparing the measured backscatter signals to theoretically expected signals computed for some well-characterized calibration target. For any given system and wavelength, the choice of calibration target is dictated by several considerations, including signal-to-noise ratio (SNR) and target availability. This paper describes the newly implemented procedures used to calibrate the 1064 nm measurements acquired by CALIOP (i.e., the Cloud-Aerosol Lidar with Orthogonal Polarization), the two-wavelength (532 and 1064 nm) elastic backscatter lidar currently flying on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission. CALIOP's 532 nm channel is accurately calibrated by normalizing the molecular backscatter from the uppermost aerosol-free altitudes of the CALIOP measurement region to molecular model data obtained from NASA's Global Modeling and Assimilation Office. However, because CALIOP's SNR for molecular backscatter measurements is prohibitively lower at 1064 nm than at 532 nm, the direct high-altitude molecular normalization method is not a viable option at 1064 nm. Instead, CALIOP's 1064 nm channel is calibrated relative to the 532 nm channel using the backscatter from a carefully selected subset of cirrus cloud measurements. In this paper we deliver a full account of the revised 1064 nm calibration algorithms implemented for the version 4.1 (V4) release of the CALIPSO lidar data products, with particular emphases on the physical basis for the selection of “calibration quality” cirrus clouds and on the new averaging scheme required to characterize intra-orbit calibration variability. The V4 procedures introduce latitudinally varying changes in the 1064 nm calibration coefficients of 25 % or more, relative to previous data releases, and are shown to substantially improve the accuracy of the V4 1064 nm attenuated backscatter coefficients. By evaluating calibration coefficients derived using both water clouds and ocean surfaces as alternate calibration targets, and through comparisons to independent, collocated measurements made by airborne high spectral resolution lidar, we conclude that the CALIOP V4 1064 nm calibration coefficients are accurate to within 3 %.

Incorporating Commercial Space Technology into Mobile Services

2011 ◽  
pp. 82-113 ◽  
Author(s):  
Phillip Olla
Keyword(s):  
Business Models ◽  
Service Providers ◽  
Global Scale ◽  
Environmental Benefits ◽  
Space Technology ◽  
Mobile Telecommunication ◽  
Space Applications ◽  
Telecommunication Infrastructure ◽  
Observation Systems ◽  
Space Infrastructure

This chapter will describe how space technologies can be incorporated into terrestrial 3G /4G mobile telecommunication infrastructure to provide convergent innovative applications and services. The utilization of space applications for non-military use has the potential to generate significant economic, social and environmental benefits on a global scale. The satellite infrastructure will become a key enabling factor in a growing range of mobile products such as: voice services, broadband Internet services, navigation, and observation systems. The chapter presents a framework derived from the literature to aid the development of viable business models expected from the amalgamation of mobile telecommunication and space infrastructure. The chapter also identifies the various actors involved in the delivery of these services which include: technology actors, service providers, network operators, consumers, and regulators.

scholarly journals The Solar-Induced Chlorophyll Fluorescence Imaging Spectrometer (SIFIS) Onboard the First Terrestrial Ecosystem Carbon Inventory Satellite (TECIS-1): Specifications and Prospects

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 815 ◽  
Author(s):  
Shanshan Du ◽  
Liangyun Liu ◽  
Xinjie Liu ◽  
Xinwei Zhang ◽  
Xianlian Gao ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Signal To Noise Ratio ◽  
Simulated Data ◽  
Terrestrial Ecosystem ◽  
Global Scale ◽  
Terrestrial Vegetation ◽  
Atmospheric Transmission ◽  
Imaging Spectrometer ◽  
Ecosystem Carbon ◽  
Carbon Inventory

The global monitoring of solar-induced chlorophyll fluorescence (SIF) using satellite-based observations provides a new way of monitoring the status of terrestrial vegetation photosynthesis on a global scale. Several global SIF products that make use of atmospheric satellite data have been successfully developed in recent decades. The Terrestrial Ecosystem Carbon Inventory Satellite (TECIS-1), the first Chinese terrestrial ecosystem carbon inventory satellite, which is due to be launched in 2021, will carry an imaging spectrometer specifically designed for SIF monitoring. Here, we use an extensive set of simulated data derived from the MODerate resolution atmospheric TRANsmission 5 (MODTRAN 5) and Soil Canopy Observation Photosynthesis and Energy (SCOPE) models to evaluate and optimize the specifications of the SIF Imaging Spectrometer (SIFIS) onboard TECIS for accurate SIF retrievals. The wide spectral range of 670−780 nm was recommended to obtain the SIF at both the red and far-red bands. The results illustrate that the combination of a spectral resolution (SR) of 0.1 nm and a signal-to-noise ratio (SNR) of 127 performs better than an SR of 0.3 nm and SNR of 322 or an SR of 0.5 nm and SNR of 472 nm. The resulting SIF retrievals have a root-mean-squared (RMS) diff* value of 0.15 mW m−2 sr−1 nm−1 at the far-red band and 0.43 mW m−2 sr−1 nm−1 at the red band. This compares with 0.20 and 0.26 mW m−2 sr−1 nm−1 at the far-red band and 0.62 and 1.30 mW m−2 sr−1 nm−1 at the red band for the other two configurations described above. Given an SR of 0.3 nm, the increase in the SNR can also improve the SIF retrieval at both bands. If the SNR is improved to 450, the RMS diff* will be 0.17 mW m−2 sr−1 nm−1 at the far-red band and 0.47 mW m−2 sr−1 nm−1 at the red band. Therefore, the SIFIS onboard TECIS-1 will provide another set of observations dedicated to monitoring SIF at the global scale, which will benefit investigations of terrestrial vegetation photosynthesis from space.

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