The measurement of atmospheric water vapor: radiometer comparison and spatial variations

Rocken, Christian; Johnson, James M.; Neilan, R. E.; Cerezo, M.; Jordan, James; Falls, M. J.; Nelson, Loren D.; Ware, Randolph; Hayes, Michael S.

doi:10.1109/36.103286

Cited by 37 publications

(12 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…MW observations with azimuthal and zenith scanning modes were used for detecting the spatial distribution of IWV in a number of studies. Rocken et al (1991) and Davis et al (1993) showed that potential differences in IVW might reach 5 mm (25%) at different azimuths (with the distance between gravity centres around 7 km). Vogelmann et al (2015) observed the spatial inhomogeneity of the IWV fields in the summer season, up to 0.35 mm for 1-2 km distance and 0.6-0.7 mm for 3-4 km.…”

Section: Discussionmentioning

confidence: 98%

Atmospheric integrated water vapour measured by IR and MW techniques at the Peterhof site (Saint Petersburg, Russia)

Virolainen

Timofeyev

Berezin

et al. 2016

International Journal of Remote Sensing

View full text Add to dashboard Cite

Regular comparison of different systems for monitoring atmospheric integrated water vapour (IWV) is part of their testing and validation protocol. We compared coincident measurements of IWV over Saint Petersburg (Russia) from ground-based Fourier-transform spectrometer Bruker IFS 125 HR (FTIR) and microwave radiometer RPG-HATPRO (MW) at the Peterhof site between March 2013 and June 2015. This study is a contribution towards global efforts to make such inter-comparisons at various ground-based sites. Since FTIR measures solar radiance, the vast majority of coincident pairs correspond to the spring and summer seasons. The numbers of measurements in the dry season (from October to April) and in the wet season (from May to September) are almost identical, comprising 616 and 638 pairs, respectively. MW and FTIR data sets demonstrate a high level of agreement: the mean relative difference between MW and FTIR data is less than 3% (0.3 mm), with standard deviation from the means of about 4% (0.4 mm). Notwithstanding the short distance between both instruments (150 m), they can monitor different air masses: MW is a zenith-viewing instrument whereas FTIR follows the sun. We analysed the FTIR observation fields under different solar zenith and azimuth angles, taking into account the location of the Peterhof site between the Gulf of Finland and rural suburbs of Saint Petersburg. Although in general MW measurements slightly overestimated IWV in comparison with the FTIR data, we detected several episodes when FTIR gave higher values than MW. These episodes relate to the FTIR observations directed at the coastal region with more humid air than that above the measurement site. We may conclude at this stage of our investigations that the spatial inhomogeneity of humidity fields in the atmosphere causes the most significant differences between the two data sets. Detailed analysis of variation in spatial IWV, e.g. using a MW radiometer in angular scanning mode, is an issue for future research. ARTICLE HISTORY

show abstract

Section: Discussionmentioning

confidence: 98%

Atmospheric integrated water vapour measured by IR and MW techniques at the Peterhof site (Saint Petersburg, Russia)

Virolainen

Timofeyev

Berezin

et al. 2016

International Journal of Remote Sensing

View full text Add to dashboard Cite

show abstract

“…The azimuthally symmetric part of the atmospheric delay is modeled in SOLVE [Ma et al, 1990] as the product of the mapping function and the zenith tropospheric delay, which is estimated pseudostochastically (as a constrained piecewise linear Ii•nction in time) IYom the data. Azimuthal asymmetries in atmospheric delay gradients have been observed [e.g., Davis et al, 1993 andRocken et al, 1991] and when gradient parameters are estimated in VLBI analysis, geodetic precision is improved [Herring, 1992;MacMillan. 1995].…”

Section: Introductionmentioning

confidence: 99%

Atmospheric gradients and the VLBI terrestrial and celestial reference frames

MacMillan

1997

Geophysical Research Letters

View full text Add to dashboard Cite

Abstract. Gradients in the atmospheric refractive index can leadto errors in estimated vertical and horizontal station coordinates.These errors produce systematic errors in the terrestrial and celestial reference frames determined from our very long baseline interferometry (VLBI) measurements. Estimation of gradients for our global VLBI data set changes the terrestrial reference frame length scale by-0.7 ppb and produces station position adjustments that vary approximately monotonically with latitude. Estimating gradients reduces the radio source declinations by an amount that peaks at about 0.5 mas near the equator and decreases toward the poles. VLBI gradient estimates are consistent with gradients derived from a global three-dimensional model of assimilated meteorological data. Both indicate that mean atmospheric delay gradients point toward the equator in both the northern and southern hemispheres. The correlation coefficient between VLBI and meteorological model gradients for VLBI sessions for the VLBI antenna at Westford, Massachusetts was 0.56.

show abstract

“…Following initial measurements of GPS signal delays induced by atmospheric water vapor (Ware et 28 al., 1986), and introduction of GPS meteorology (Rocken et al, 1991;Bevis et al, 1992), remarkable 29 progress in using ground based GPS receivers for atmospheric water vapor sensing has been achieved 30 (Rocken et al, 1993(Rocken et al, , 1997Gendt et al, 2004;Shoji et al, 2011). GPS-based zenith total delays (ZTD) 31 and integrated water vapor (IWV) data products, derived in near real-time, have been assimilated into 32 numerical weather prediction (NWP) models.…”

mentioning

confidence: 99%

Multi-GNSS Meteorology: Real-Time Retrieving of Atmospheric Water Vapor From BeiDou, Galileo, GLONASS, and GPS Observations

Dick

et al. 2015

IEEE Trans. Geosci. Remote Sensing

139

View full text Add to dashboard Cite

show abstract

The measurement of atmospheric water vapor: radiometer comparison and spatial variations

Cited by 37 publications

References 12 publications

Atmospheric integrated water vapour measured by IR and MW techniques at the Peterhof site (Saint Petersburg, Russia)

Atmospheric integrated water vapour measured by IR and MW techniques at the Peterhof site (Saint Petersburg, Russia)

Atmospheric gradients and the VLBI terrestrial and celestial reference frames

Multi-GNSS Meteorology: Real-Time Retrieving of Atmospheric Water Vapor From BeiDou, Galileo, GLONASS, and GPS Observations

Contact Info

Product

Resources

About