scholarly journals GNSS-based water vapor estimation and validation during the MOSAiC expedition

2021 ◽  
Author(s):  
Benjamin Männel ◽  
Florian Zus ◽  
Galina Dick ◽  
Susanne Glaser ◽  
Maximilian Semmling ◽  
...  
Keyword(s):  
Water Vapor ◽  
Very Long Baseline Interferometry ◽  
Precise Point Positioning ◽  
Radiosonde Data ◽  
Weather Data ◽  
Radio Telescopes ◽  
Long Baseline ◽  
Gnss Data ◽  
Level Of Agreement ◽  
Good Agreement

Abstract. Within the transpolar drifting expedition MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), GNSS was used among other techniques to monitor variations in atmospheric water vapor. Based on 15 months of continuously tracked GNSS data including GPS, GLONASS, and Galileo, epoch-wise coordinates and hourly zenith total delays (ZTD) were determined using a kinematic precise point positioning (PPP) approach. The derived ZTD values agree to 1.1 ± 0.2 mm (RMS of the differences 10.2 mm) with the numerical weather data of ECMWF’s latest reanalysis, ERA5, computed for the derived ship’s locations. This level of agreement is also confirmed by comparing the on-board estimates with ZTDs derived for terrestrial GNSS stations in Bremerhaven and Ny Ålesund and for the radio telescopes observing Very Long Baseline Interferometry in Ny Ålesund. Preliminary estimates of integrated water vapor derived from frequently launched radiosondes are used to assess the GNSS-derived integrated water vapor estimates. The overall difference of 0.08 ± 0.04 kg m−2 (RMS of the differences 1.47 kg m−2) demonstrates a good agreement between GNSS and radiosonde data. Finally, the water vapor variations associated with two warm air intrusion events in April 2020 are assessed.

scholarly journals GNSS-based water vapor estimation and validation during the MOSAiC expedition

2021 ◽  
Vol 14 (7) ◽  
pp. 5127-5138
Author(s):  
Benjamin Männel ◽  
Florian Zus ◽  
Galina Dick ◽  
Susanne Glaser ◽  
Maximilian Semmling ◽  
...  
Keyword(s):  
Water Vapor ◽  
Very Long Baseline Interferometry ◽  
Satellite System ◽  
Radiosonde Data ◽  
Weather Data ◽  
Long Baseline ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
Level Of Agreement ◽  
Good Agreement

Abstract. Within the transpolar drifting expedition MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), the Global Navigation Satellite System (GNSS) was used among other techniques to monitor variations in atmospheric water vapor. Based on 15 months of continuously tracked GNSS data including GPS, GLONASS and Galileo, epoch-wise coordinates and hourly zenith total delays (ZTDs) were determined using a kinematic precise point positioning (PPP) approach. The derived ZTD values agree to 1.1 ± 0.2 mm (root mean square (rms) of the differences 10.2 mm) with the numerical weather data of ECMWF's latest reanalysis, ERA5, computed for the derived ship's locations. This level of agreement is also confirmed by comparing the on-board estimates with ZTDs derived for terrestrial GNSS stations in Bremerhaven and Ny-Ålesund and for the radio telescopes observing very long baseline interferometry in Ny-Ålesund. Preliminary estimates of integrated water vapor derived from frequently launched radiosondes are used to assess the GNSS-derived integrated water vapor estimates. The overall difference of 0.08 ± 0.04 kg m−2 (rms of the differences 1.47 kg m−2) demonstrates a good agreement between GNSS and radiosonde data. Finally, the water vapor variations associated with two warm-air intrusion events in April 2020 are assessed.

scholarly journals Station Infrastructure Developments of the IVS

2020 ◽  
Author(s):  
Dirk Behrend ◽  
Axel Nothnagel ◽  
Johannes Böhm ◽  
Chet Ruszczyk ◽  
Pedro Elosegui
Keyword(s):  
Very Long Baseline Interferometry ◽  
Global Network ◽  
Radio Telescopes ◽  
Geodetic Vlbi ◽  
The Past ◽  
Long Baseline ◽  
Aging Infrastructure ◽  
Recent Developments ◽  
International Vlbi Service ◽  
Vlbi Data

<p>The International VLBI Service for Geodesy and Astrometry (IVS) is a globally operating service that coordinates and performs Very Long Baseline Interferometry (VLBI) activities through its constituent components. The VLBI activities are associated with the creation, provision, dissemination, and archiving of relevant VLBI data and products. The operational station network of the IVS currently consists of about 40 radio telescopes worldwide, subsets of which participate in regular 24-hour and 1-hour observing sessions. This legacy S/X observing network dates back in large part to the 1970s and 1980s. Because of highly demanding new scientific requirements such as sea-level change but also due to the aging infrastructure, the larger IVS community planned and started to implement a new VLBI system called VGOS (VLBI Global Observing System) at existing and new sites over the past several years. In 2020, a fledgling network of 8 VGOS stations started to observe in operational IVS sessions. We anticipate that the VGOS network will grow over the next couple of years to a global network of 25 stations and will eventually replace the legacy S/X system as the IVS production system. We will provide an overview of the recent developments and anticipated evolution of the geodetic VLBI station infrastructure.</p>

scholarly journals Water Vapor Mixing Ratio Distribution Inversion by Raman Lidar in Beijing

2020 ◽  
Vol 237 ◽  
pp. 06020
Author(s):  
SiQi Yu ◽  
Dong Liu ◽  
JiWei Xu ◽  
ZhenZhu Wang ◽  
DeCheng Wu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Radiosonde Data ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Ratio Distribution ◽  
Water Vapor Mixing Ratio ◽  
Detection Instrument ◽  
Active Detection ◽  
The Vertical Distribution ◽  
Good Agreement

Water Aerosol Raman Lidar-II is an active detection instrument with high temporal and spatial resolution at Nanjiao observation station, and that could continuous water vapor mixing ratio (WVMR) measurements. WVMR profiles inversion from lidar data and water ratio retrieved from radiosonde data are in good agreement. The statistical results of the vertical distribution of WVMR indicate that WVMR seasonal mean distribution is consistent with precipitation. In addition, WVMR in Nanjiao station is related to total cloud cover.

scholarly journals Agreements and Disagreements between Theories of Rigid Earth Nutation

1997 ◽  
Vol 165 ◽  
pp. 319-324
Author(s):  
J. Souchay
Keyword(s):  
Very Long Baseline Interferometry ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Theoretical Determination ◽  
Long Baseline ◽  
The Earth ◽  
Lunar Laser ◽  
Rigid Earth ◽  
Good Agreement

AbstractThe necessity to elaborate a theory of nutation and precession matching the accuracy of very modern techniques as Very Long Baseline Interferometry and Lunar Laser Ranging led recently to various works. We discuss here the good agreement between those related to the nutation when considering the Earth as a solid body. In comparison we show the uncertainty concerning the modelisation of the transfer function leading to theoretical determination of the nutation coefficients when including dominant geophysical characteristics.

scholarly journals IASI temperature and water vapor retrievals – error assessment and validation

2009 ◽  
Vol 9 (17) ◽  
pp. 6453-6458 ◽  
Author(s):  
N. Pougatchev ◽  
T. August ◽  
X. Calbet ◽  
T. Hultberg ◽  
O. Oduleye ◽  
...  
Keyword(s):  
Water Vapor ◽  
Assessment Model ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Statistical Validation ◽  
Data Set ◽  
Error Covariance ◽  
Recent Version ◽  
Level 2 ◽  
Good Agreement

Abstract. The METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI) Level 2 products comprise retrievals of vertical profiles of temperature and water vapor. The error covariance matrices and biases of the most recent version (4.3.1) of the L2 data were assessed, and the assessment was validated using radiosonde data for reference. The radiosonde data set includes dedicated and synoptic time launches at the Lindenberg station in Germany. For optimal validation, the linear statistical Validation Assessment Model (VAM) was used. The VAM uses radiosonde profiles as input and provides optimal estimate of the nominal IASI retrieval by utilizing IASI averaging kernels and statistical characteristics of the ensembles of the reference radiosondes. For temperatures above 900 mb and water retrievals above 700 mb, level expected and assessed errors are in good agreement. Below those levels, noticeable excess in assessed error is observed, possibly due to inaccurate surface parameters and undetected clouds/haze.

Stability monitoring of a stationary VLBI antenna

1983 ◽  
Vol 20 (10) ◽  
pp. 1586-1597 ◽  
Author(s):  
W. F. Teskey ◽  
W. Niemeier ◽  
M. Sideris ◽  
R. G. Lyall
Keyword(s):  
Very Long Baseline Interferometry ◽  
Monitoring Network ◽  
Numerical Results ◽  
Sensitivity Analyses ◽  
Radio Telescopes ◽  
Monitoring Networks ◽  
Tectonic Plates ◽  
Stability Monitoring ◽  
Mathematical Background ◽  
Long Baseline

The proposed Canadian Long Baseline Array (CLBA) and the use of several radio telescopes in the CLBA as very long baseline interferometry (VLBI) stations to determine possible movements of tectonic plates are briefly described. The need for a monitoring network surrounding each VLBI antenna is explained, and expected movement between two possible VLBI stations is estimated. The mathematical background of precision, reliability, and sensitivity analyses is outlined. These analyses are then applied to an actual monitoring network. The numerical results are discussed to show how these analyses are particularly useful for monitoring networks.

scholarly journals Orbiting VLBI: A Survey

1984 ◽  
Vol 110 ◽  
pp. 397-403
Author(s):  
Bernard F. Burke
Keyword(s):  
Very Long Baseline Interferometry ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Limiting Factor ◽  
Space Vehicles ◽  
Radio Telescopes ◽  
Long Baseline ◽  
The Earth ◽  
Effective Aperture ◽  
High Dynamic

The Very-Long-Baseline Interferometry technique is not limited by the size of the Earth. Near-Earth-orbiting space vehicles can carry radio telescopes that can serve as VLBI stations using existing technology. By proper use of ground VLB arrays, a single orbiting VLBI satellite can yield radio maps with 2-dimensional coverage and high dynamic range at all declinations. A single orbiter can be used out to orbits that yield an effective aperture greater than two Earth diameters. Interstellar scintillations are a limiting factor only in the micro-arc-second range.

scholarly journals Short Baseline Observations at Geodetic Observatory Wettzell

Data ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 64 ◽  
Author(s):  
Apurva Phogat ◽  
Gerhard Kronschnabl ◽  
Christian Plötz ◽  
Walter Schwarz ◽  
Torben Schüler
Keyword(s):  
Meteorological Parameters ◽  
Very Long Baseline Interferometry ◽  
Final Analysis ◽  
Barometric Pressure ◽  
Radio Telescopes ◽  
Short Baseline ◽  
Long Baseline ◽  
Log Files ◽  
University Of Munich ◽  
Clock Offset

The Geodetic Observatory Wettzell (GOW), jointly operated by the Federal Agency for Cartography and Geodesy (BKG), Germany and the Technical University of Munich, Germany is equipped with three radio telescopes for Very Long Baseline Interferometry (VLBI). Correlation capability is primarily designed for relative positioning of the three Wettzell radio telescopes i.e., to derive the local ties between the three telescopes from VLBI raw data in addition to the conventional terrestrial surveys. A computing cluster forming the GO Wettzell Local Correlator (GOWL) was installed in 2017 as well as the Distributed FX (DiFX) software correlation package and the Haystack Observatory Postprocessing System (HOPS) for fringe fitting and postprocessing of the output. Data pre-processing includes ambiguity resolution (if necessary) as well as the generation of the geodetic database and NGS card files with υ Solve. The final analysis is either carried out with local processing software (LEVIKA short baseline analysis) or with the Vienna VLBI and Satellite (VieVS) software. We will present an overview of the scheduling, correlation and analysis capabilities at GOW and results obtained so. The dataset includes auxiliary files (schedule and log files) which contain information about the participating antenna, observed sources, clock offset between formatter and GPS time, cable delay, meteorological parameters (temperature, barometric pressure, and relative humidity) and ASCII files created after fringe fitting and final analysis. The published dataset can be used by the researchers and scientists to further explore short baseline interferometry.

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