scholarly journals Retrieval of Water Constituents from Hyperspectral In-Situ Measurements under Variable Cloud Cover—A Case Study at Lake Stechlin (Germany)

2018 ◽  
Vol 10 (2) ◽  
pp. 181 ◽  
Author(s):  
Anna Göritz ◽  
Stella Berger ◽  
Peter Gege ◽  
Hans-Peter Grossart ◽  
Jens Nejstgaard ◽  
...  
Keyword(s):  
Cloud Cover ◽  
In Situ Measurements ◽  
Water Constituents ◽  
Lake Stechlin

scholarly journals Synergetic monitoring of Saharan dust plumes and potential impact on surface: a case study of dust transport from Canary Islands to Iberian Peninsula

2011 ◽  
Vol 11 (7) ◽  
pp. 3067-3091 ◽  
Author(s):  
C. Córdoba-Jabonero ◽  
M. Sorribas ◽  
J. L. Guerrero-Rascado ◽  
J. A. Adame ◽  
Y. Hernández ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Particle Deposition ◽  
Ground Level ◽  
In Situ Measurements ◽  
Saharan Dust ◽  
Dust Transport ◽  
Air Masses ◽  
Potential Impact

Abstract. The synergetic use of meteorological information, remote sensing both ground-based active (lidar) and passive (sun-photometry) techniques together with backtrajectory analysis and in-situ measurements is devoted to the characterization of dust intrusions. A case study of air masses advected from the Saharan region to the Canary Islands and the Iberian Peninsula, located relatively close and far away from the dust sources, respectively, was considered for this purpose. The observations were performed over three Spanish geographically strategic stations within the dust-influenced area along a common dust plume pathway monitored from 11 to 19 of March 2008. A 4-day long dust event (13–16 March) over the Santa Cruz de Tenerife Observatory (SCO), and a linked short 1-day dust episode (14 March) in the Southern Iberian Peninsula over the Atmospheric Sounding Station "El Arenosillo" (ARN) and the Granada station (GRA) were detected. Meteorological conditions favoured the dust plume transport over the area under study. Backtrajectory analysis clearly revealed the Saharan region as the source of the dust intrusion. Under the Saharan air masses influence, AERONET Aerosol Optical Depth at 500 nm (AOD500) ranged from 0.3 to 0.6 and Ångström Exponent at 440/675 nm wavelength pair (AE440/675) was lower than 0.5, indicating a high loading and predominance of coarse particles during those dusty events. Lidar observations characterized their vertical layering structure, identifying different aerosol contributions depending on altitude. In particular, the 3-km height dust layer transported from the Saharan region and observed over SCO site was later on detected at ARN and GRA stations. No significant differences were found in the lidar (extinction-to-backscatter) ratio (LR) estimation for that dust plume over all stations when a suitable aerosol scenario for lidar data retrieval is selected. Lidar-retrieved LR values of 60–70 sr were obtained during the main dust episodes. These similar LR values found in all the stations suggest that dust properties were kept nearly unchanged in the course of its medium-range transport. In addition, the potential impact on surface of that Saharan dust intrusion over the Iberian Peninsula was evaluated by means of ground-level in-situ measurements for particle deposition assessment together with backtrajectory analysis. However, no connection between those dust plumes and the particle sedimentation registered at ground level is found. Differences on particle deposition processes observed in both Southern Iberian Peninsula sites are due to the particular dust transport pattern occurred over each station. Discrepancies between columnar-integrated and ground-level in-situ measurements show a clear dependence on height of the dust particle size distribution. Then, further vertical size-resolved observations are needed for evaluation of the impact on surface of the Saharan dust arrival to the Iberian Peninsula.

Comparison of different in situ measurements techniques of intelligibility in an open-plan office

2018 ◽  
Vol 25 (2) ◽  
pp. 111-122 ◽  
Author(s):  
Dario D’Orazio ◽  
Elena Rossi ◽  
Massimo Garai
Keyword(s):  
Direct Method ◽  
Measurement Techniques ◽  
Background Level ◽  
In Situ Measurements ◽  
Sound Sources ◽  
Transmission Index ◽  
Acoustic Comfort ◽  
Open Plan

Acoustic comfort in open-plan offices is a relatively recent research topic and some practices have not yet been consolidated. The goal in these spaces is to achieve good speech privacy at every workstation, reaching a high value of spatial decay of the sound pressure level. In case of refurbishment, a proper measurement of intelligibility criteria is needed, for example, in order to properly calibrate a numerical model or to plan acoustic treatments. This work compares different measurement techniques to evaluate the spatial distribution of intelligibility criteria. In situ measurements were done in an open-plan office used as a case study. Both omnidirectional and directional sound sources with different sound power levels were used, according, respectively, to ISO 3382-3:2012 and ITU-T P.51:1996. Furthermore, compensation algorithms were used in impulse response measurements in presence of Heating, Ventilation and Air Conditioning noise. The study shows, in a preliminary way, how different techniques and equipment can influence intelligibility criteria used in the open-plan office characterization. Results show that the indirect method of measuring Speech Transmission Index could not be used when the background level is high as the case study while the direct method returns good results.

scholarly journals The retrieval of cloud microphysical properties using satellite measurements and an in situ database

1996 ◽  
Vol 14 (1) ◽  
pp. 98-106 ◽  
Author(s):  
Christophe Poix ◽  
Guy Febvre ◽  
Anne Fouilloux ◽  
Howard Larsen ◽  
Jean-Francois Gayet
Keyword(s):  
Large Scale ◽  
In Situ Measurements ◽  
Global Circulation ◽  
The North ◽  
Microphysical Properties ◽  
Microphysical Parameters ◽  
Research Aircraft ◽  
The North Sea

Abstract. By combining AVHRR data from the NOAA satellites with information from a database of in situ measurements, large-scale maps can be generated of the microphysical parameters most immediately significant for the modelling of global circulation and climate. From the satellite data, the clouds can be classified into cumuliform, stratiform and cirrus classes and then into further sub-classes by cloud top temperature. At the same time a database of in situ measurements made by research aircraft is classified into the same sub-classes and a statistical analysis is used to derive relationships between the sub-classes and the cloud microphysical properties. These two analyses are then linked to give estimates of the microphysical properties of the satellite observed clouds. Examples are given of the application of this technique to derive maps of the probability of occurrence of precipitating clouds and of precipitating water content derived from a case study within the International Cirrus Experiment (ICE) held in 1989 over the North Sea.

scholarly journals Ice particle formation and sedimentation in the tropopause region: A case study based on in situ measurements of total water during POLSTAR 1997

1999 ◽  
Vol 26 (14) ◽  
pp. 2219-2222 ◽  
Author(s):  
C. Schiller ◽  
A. Afchine ◽  
N. Eicke ◽  
C. Feigl ◽  
H. Fischer ◽  
...  
Keyword(s):  
Particle Formation ◽  
In Situ Measurements ◽  
Total Water ◽  
Tropopause Region
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