scholarly journals MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

2010 ◽  
Vol 3 (3) ◽  
pp. 2389-2432
Author(s):  
C. Straub ◽  
A. Murk ◽  
N. Kaempfer
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Horn Antenna ◽  
Profile Measurement ◽  
Correlation Receiver ◽  
Water Vapor Radiometer ◽  
Set Up ◽  
Compact Design ◽  
Crucial Parameter ◽  
Measurement Campaigns

Abstract. In this paper a new 22 GHz water vapor spectro-radiometer which has been specifically designed for profile measurement campaigns of the middle atmosphere is presented. The instrument is of a compact design and has a simple set up procedure. It can be operated as a standalone instrument as it maintains its own weather station and a calibration scheme that does not rely on other instruments or the use of liquid nitrogen. The optical system of MIAWARA-C combines a choked gaussian horn antenna with a parabolic mirror which reduces the size of the instrument in comparison with currently existing radiometers. For the data acquisition a correlation receiver is used together with a digital cross correlating spectrometer. The complete backend section, including the computer, is located in the same housing as the instrument. The receiver section is temperature stabilized to avoid gain fluctuations. Calibration of the instrument is achieved through a balancing scheme with the sky used as the cold load and the tropospheric properties are determined by performing regular tipping curves. Since MIAWARA-C is used in measurement campaigns it is important to be able to determine the elevation pointing in a simple manner as this is a crucial parameter in the calibration process. Here we present two different methods; scanning the sky and the Sun. Finally, we report on the first spectra and retrieved water vapor profiles acquired during the Lapbiat campaign at Sodankylä Geophysical Observatory. The performance of MIAWARA-C is validated here by comparison of the presented profiles against the equivalent profiles from the Microwave Limb Sounder on the EOS/Aura satellite.

scholarly journals MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

2010 ◽  
Vol 3 (5) ◽  
pp. 1271-1285 ◽  
Author(s):  
C. Straub ◽  
A. Murk ◽  
N. Kämpfer
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Horn Antenna ◽  
Research Centre ◽  
Profile Measurement ◽  
Finnish Meteorological Institute ◽  
Correlation Receiver ◽  
Set Up ◽  
Compact Design ◽  
Measurement Campaigns

Abstract. In this paper a new 22 GHz water vapor spectro-radiometer which has been specifically designed for profile measurement campaigns of the middle atmosphere is presented. The instrument is of a compact design and has a simple set up procedure. It can be operated as a standalone instrument as it maintains its own weather station and a calibration scheme that does not rely on other instruments or the use of liquid nitrogen. The optical system of MIAWARA-C combines a choked gaussian horn antenna with a parabolic mirror which reduces the size of the instrument in comparison with currently existing radiometers. For the data acquisition a correlation receiver is used together with a digital cross correlating spectrometer. The complete backend section, including the computer, is located in the same housing as the instrument. The receiver section is temperature stabilized to minimize gain fluctuations. Calibration of the instrument is achieved through a balancing scheme with the sky used as the cold load and the tropospheric properties are determined by performing regular tipping curves. Since MIAWARA-C is used in measurement campaigns it is important to be able to determine the elevation pointing in a simple manner as this is a crucial parameter in the calibration process. Here we present two different methods; scanning the sky and the Sun. Finally, we report on the first spectra and retrieved water vapor profiles acquired during the Lapbiat campaign at the Finnish Meteorological Institute Arctic Research Centre in Sodankylä, Finland. The performance of MIAWARA-C is validated here by comparison of the presented profiles against the equivalent profiles from the Microwave Limb Sounder on the EOS/Aura satellite.

The Seoul Water Vapor Radiometer for the Middle Atmosphere: Calibration, Retrieval, and Validation

2011 ◽  
Vol 49 (3) ◽  
pp. 1052-1062 ◽  
Author(s):  
Evelyn De Wachter ◽  
Alexander Haefele ◽  
Niklaus Kampfer ◽  
Soohyun Ka ◽  
Jung Eun Lee ◽  
...  
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Water Vapor Radiometer

Proposed reference model for middle atmosphere water vapor

1996 ◽  
Vol 18 (9-10) ◽  
pp. 59-89 ◽  
Author(s):  
E.W. Chiou ◽  
E.E. Remsberg ◽  
C.D. Rodgers ◽  
R. Munro ◽  
R.M. Bevilacqua ◽  
...  
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Reference Model

scholarly journals Development of a high-stability water vapor radiometer

Radio Science ◽  
1998 ◽  
Vol 33 (2) ◽  
pp. 449-462 ◽  
Author(s):  
Alan B. Tanner
Keyword(s):  
Water Vapor ◽  
High Stability ◽  
Water Vapor Radiometer

Pointed water vapor radiometer corrections for accurate global positioning system surveying

1993 ◽  
Vol 20 (23) ◽  
pp. 2635-2638 ◽  
Author(s):  
Randolph Ware ◽  
Christian Rocken ◽  
Fredrick Solheim ◽  
Teresa Van Hove ◽  
Chris Alber ◽  
...  
Keyword(s):  
Water Vapor ◽  
Global Positioning System ◽  
Positioning System ◽  
Global Positioning ◽  
Water Vapor Radiometer

Trends in noctilucent clouds

2021 ◽  
Author(s):  
Franz-Josef Lübken ◽  
Gerd Baumgarten
Keyword(s):  
Carbon Dioxide ◽  
Water Vapor ◽  
Middle Atmosphere ◽  
Transport Model ◽  
Particle Model ◽  
Noctilucent Clouds ◽  
Middle Latitudes ◽  
Ice Particles ◽  
Highly Correlated ◽  
Ice Water

<p>Noctilucent clouds are often cited as potential indicators of climate change in the middle<br>atmosphere. They owe their existence to the very cold summer mesopause region (~130K) at mid<br>and high latitudes. We analyze trends derived from the Leibniz-Institute Middle Atmosphere<br>Model (LIMA) and the MIMAS ice particle model (Mesospheric Ice Microphysics And tranSport model)<br>for the years 1871-2008 and for middle, high and arctic latitudes, respectively.<br>Model runs with and without an increase of carbon dioxide and water vapor (from methane oxidation)<br>concentration are performed. Trends are most prominent after ~1960 when the increase of both<br>carbon dioxide and water vapor accelerates. Negative trends of (geometric) NLC altitudes are primarily<br>due to cooling below NLC altitudes caused by carbon dioxide increase. Increases of ice particle<br>radii and NLC brightness with time are mainly caused by an enhancement of water vapor.<br>Several ice layer and background parameter trends are similar at high and arctic latitudes but are<br>substantially different at middle latitudes. This concerns, for example, occurrence rates, ice water<br>content (IWC), and number of ice particles in a column. Considering the time period after 1960,<br>geometric altitudes of NLC decrease by approximately 260m per decade, and brightness increases by<br>roughly 50% (1960-2008), independent of latitude. NLC altitudes decrease by approximately 15-20m<br>per increase of carbon dioxide by 1ppmv. The number of ice particles in a column and also at the<br>altitude of maximum backscatter is nearly constant with time. At all latitudes, yearly mean NLC<br>appear at altitudes where temperatures are close to 145+/-1K. Ice particles are present nearly<br>all the time at high and arctic latitudes, but are much less common at middle latitudes. Ice water<br>content and maximum backscatter are highly correlated, where the slope depends on latitude. This<br>allows to combine data sets from satellites and lidars. Furthermore, IWC and the concentration of<br>water vapor at the altitude of maximum backscatter are also strongly correlated. Results from<br>LIMA/MIMAS agree nicely with observations.</p>

scholarly journals Methods of Correction for the “Wet” Atmosphere in Estimating Baseline Lengths from VLBI

1988 ◽  
Vol 129 ◽  
pp. 543-544
Author(s):  
G. Elgered ◽  
J. L. Davis ◽  
T. A. Herring ◽  
I. I. Shapiro
Keyword(s):  
Water Vapor ◽  
Propagation Delay ◽  
Propagation Path ◽  
Baseline Length ◽  
Space Observatory ◽  
Owens Valley ◽  
Use Of Data ◽  
Onsala Space Observatory ◽  
Vlbi Data ◽  
Water Vapor Radiometer

The error in VLBI estimates of baseline length caused by unmodelled variations in the propagation path through the atmosphere is greater for longer baselines. We present and discuss series of estimates of baseline lengths obtained using different methods to correct for the propagation delay caused by atmospheric water vapor. The main methods are use of data from a water-vapor radiometer (WVR) and Kalman-filtering of the VLBI data themselves to estimate the propagation delay. Since the longest timespan of WVR data associated with geodetic VLBI experiments was obtained at the Onsala Space Observatory in Sweden, we present results for the following three baselines: (1) Onsala–Wettzell, FRG (920 km), (2) Onsala–Haystack/Westford, MA (5600 km), and (3) Onsala–Owens Valley (7914 km).

scholarly journals Railway Ballast Monitoring by Gpr: A Test Site Investigation

2019 ◽  
Vol 11 (20) ◽  
pp. 2381 ◽  
Author(s):  
Bianchini Ciampoli ◽  
Calvi ◽  
D’Amico
Keyword(s):  
Asset Management ◽  
Construction Materials ◽  
Site Investigation ◽  
Horn Antenna ◽  
Test Site ◽  
Electromagnetic Response ◽  
Actual Condition ◽  
Railway Ballast ◽  
Set Up ◽  
Ground Penetrating

Effective maintenance of railways requires a comprehensive assessment of the actual condition of the construction materials involved. In this regard, Ground-Penetrating Radar (GPR) stands as a viable alternative to the invasive and time-consuming traditional techniques for the inspection of these infrastructures. This work reports the experimental activities carried out on a test-site area within a railway depot in Rome, Italy. To this purpose, a 30 m-long railway section was divided into 10 sub-sections reproducing different various physical and structural conditions of the track-bed. In more detail, combinations of varying scenarios of fragmentation and fouling of the ballast were reproduced. The set-up was then investigated using different multi-frequency GPR horn antenna systems. The effects of the different physical conditions of ballast on the electromagnetic response of the material were analysed for each scenario using time- and frequency-domain signal processing techniques. Parallel to this, modelling was provided to estimate fouling content. Interpretation of results has proven the viability of the GPR method in detecting signs of decay at the network level, thereby proving this technique to be worthy of implementation in asset management systems.

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