Comparison of SAGE-II and HIRS co-located cloud height measurements

1999 ◽  
Vol 26 (22) ◽  
pp. 3373-3375 ◽  
Author(s):  
Donald P. Wylie ◽  
Pi-Huan Wang
Keyword(s):  
Cloud Height

scholarly journals A novel approach for the extraction of cloud motion vectors using airglow imager measurements

2015 ◽  
Vol 8 (9) ◽  
pp. 3893-3901 ◽  
Author(s):  
S. Satheesh Kumar ◽  
T. Narayana Rao ◽  
A. Taori
Keyword(s):  
Meridional Wind ◽  
Noise Removal ◽  
Search Window ◽  
Motion Vectors ◽  
Good Correspondence ◽  
Cloud Motion ◽  
Cloud Height ◽  
Novel Approach ◽  
Wind Velocities ◽  
Cloud Tracking

Abstract. The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in both the zonal and meridional wind velocities with RMSEs < 2.4 m s−1. Finally, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.

scholarly journals Cloud height and tracking accuracy of three all sky imager systems for individual clouds

Solar Energy ◽  
2019 ◽  
Vol 177 ◽  
pp. 213-228 ◽  
Author(s):  
B. Nouri ◽  
P. Kuhn ◽  
S. Wilbert ◽  
N. Hanrieder ◽  
C. Prahl ◽  
...  
Keyword(s):  
Tracking Accuracy ◽  
Cloud Height ◽  
Sky Imager

Benchmarking three low-cost, low-maintenance cloud height measurement systems and ECMWF cloud heights against a ceilometer

Solar Energy ◽  
2018 ◽  
Vol 168 ◽  
pp. 140-152 ◽  
Author(s):  
P. Kuhn ◽  
M. Wirtz ◽  
N. Killius ◽  
S. Wilbert ◽  
J.L. Bosch ◽  
...  
Keyword(s):  
Low Cost ◽  
Height Measurement ◽  
Measurement Systems ◽  
Cloud Height

Validation of Sentinel-5p TROPOMI cloud data with ground-based Cloudnet and other satellite data products

2021 ◽  
Author(s):  
Steven Compernolle ◽  
Athina Argyrouli ◽  
Ronny Lutz ◽  
Maarten Sneep ◽  
Jean-Christopher Lambert ◽  
...  
Keyword(s):  
Major Change ◽  
Recognition Algorithm ◽  
Atmospheric Composition ◽  
Trace Gas ◽  
Oxygen Absorption ◽  
Absorption Bands ◽  
Cloud Data ◽  
Cloud Height ◽  
Data Products ◽  
Retrieval Scheme

&lt;p&gt;Space-born atmospheric composition measurements, like those from Sentinel-5p TROPOMI, are strongly affected by the presence of clouds. Dedicated cloud data products, typically retrieved with the same sensor, are therefore an important tool for the provider of atmospheric trace gas retrievals. Cloud products are used for filtering and modification of the modelled radiative transfer.&lt;/p&gt;&lt;p&gt;In this work, we assess the quality of the cloud data derived from Copernicus Sentinel-5 Precursor TROPOMI radiance measurements. Three cloud products are considered: (i) L2_CLOUD OCRA/ROCINN CAL (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks; Clouds-As-Layers), (ii) L2_CLOUD OCRA/ROCINN CRB (same; Clouds-as Reflecting Boundaries), and (iii) the S5p support product FRESCO-S (Fast Retrieval Scheme for Clouds from Oxygen absorption bands for Sentinel). These cloud products are used in the retrieval of several S5p trace gas products (e.g., ozone columns and profile, total and tropospheric nitrogen dioxide, sulfur dioxide, formaldehyde). The quality assessment of these cloud products is carried out within the framework of ESA&amp;#8217;s Sentinel-5p Mission Performance Centre (MPC) with support from AO validation projects focusing on the respective atmospheric gases.&lt;/p&gt;&lt;p&gt;Cloud height data from the three S5p cloud products is compared to radar/lidar based cloud profile information from the ground-based networks CLOUDNET and ARM. The cloud height from S5p CLOUD CRB and S5p FRESCO are on average 0.6 km below the cloud mid-height of CLOUDNET measurements, and the cloud top height from S5p CLOUD CAL is on average 1 km below CLOUDNET&amp;#8217;s cloud top height. However, the comparison is different for low and high clouds, with S5p CLOUD CAL cloud top height being only 0.3 km below CLOUDNET&amp;#8217;s for low clouds.&amp;#160; The radiometric cloud fraction and cloud (top) height are compared to those of other satellite cloud products like Aura OMI O&lt;sub&gt;2&lt;/sub&gt;-O&lt;sub&gt;2&lt;/sub&gt;. While the latitudinal variation is often similar, offsets are encountered.&lt;/p&gt;&lt;p&gt;Recently, major S5p cloud product upgrades were released for S5p OCRA/ROCINN (July 2020) and for S5p FRESCO (December 2020), leading to a decrease of the ROCINN CRB cloud height and an increase of the FRESCO cloud height on average. Moreover, a major change in the ROCINN surface albedo treatment leads to a clear improvement of the comparison with CLOUDNET at the complicated sea/land/ice/snow site Ny-Alesund.&lt;/p&gt;&lt;div&gt;&lt;/div&gt;

Radar as an Aid to the Study of the Atmosphere

1949 ◽  
Vol 53 (461) ◽  
pp. 433-448 ◽  
Author(s):  
F. E. Jones
Keyword(s):  
Wind Speed ◽  
Experimental Work ◽  
List Type ◽  
Type Number ◽  
Normal Functions ◽  
Cloud Height ◽  
Temperature And Humidity ◽  
Post War ◽  
Humidity Profiles

SummaryApart from its normal functions in aviation the applications of radar have been few. In the post-war period T.R.E., in conjunction with the Meteorological Office, have been making a study of possible uses of radar to the science of meteorology and the results of these investigations are described in this paper.In the experimental work radar has been used to: —(a)investigate precipitation,(b)detect clouds dangerous to flying,(c)measure cloud height, and(d)measure wind speed and direction.An account is given of how radar may be used to measure the density of the atmosphere at altitudes up to many tens of miles and of some problems still to be solved in the design of a radar sonde system for measuring pressure, temperature and humidity profiles.It is concluded that radar will become an established meteorological tool and some possible profitable future lines of research are indicated.

Experimental and Measurement Uncertainty Associated With Characterizing Slurry Mixing Performance of Pulsating Jets at Multiple Scales

2015 ◽  
Author(s):  
Judith Ann Bamberger ◽  
Greg F. Piepel ◽  
Carl W. Enderlin ◽  
Brett G. Amidan ◽  
Alejandro Heredia-Langner
Keyword(s):  
Measurement Uncertainty ◽  
Multiple Scales ◽  
Experimental Tests ◽  
Experimental Results ◽  
Cloud Height ◽  
Solids Concentration ◽  
Relative Standard ◽  
Measurement Uncertainties ◽  
Standard Deviations ◽  
Pulsating Jets

Understanding how uncertainty manifests itself in complex experiments is important for developing the testing protocol and interpreting the experimental results. This paper describes experimental and measurement uncertainties, and how they can depend on the order of performing experimental tests. Experiments with pulse-jet mixers in tanks at three scales were conducted to characterize the performance of transient-developing periodic flows in Newtonian slurries. Other test parameters included the simulant, solids concentration, and nozzle exit velocity. Critical suspension velocity and cloud height were the metrics used to characterize Newtonian slurry flow associated with mobilization and mixing. During testing, near-replicate and near-repeat tests were conducted. The experimental results were used to quantify the combined experimental and measurement uncertainties using standard deviations and percent relative standard deviations (%RSD) The uncertainties in critical suspension velocity and cloud height tend to increase with the values of these responses. Hence, the %RSD values are the more appropriate summary measure of near-replicate testing and measurement uncertainty.

Analysis of particle cloud height dynamics in a stirred tank

AIChE Journal ◽  
2015 ◽  
Vol 62 (1) ◽  
pp. 338-348
Author(s):  
Matthias Eng ◽  
Rasmus Jonsson ◽  
Anders Rasmuson
Keyword(s):  
Stirred Tank ◽  
Particle Cloud ◽  
Cloud Height
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