Ground‐based microwave radiometry and long‐term observations of atmospheric water vapor

Elgered, Gunnar; Jarlemark, Per

doi:10.1029/98rs00488

Cited by 40 publications

(31 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They have also been used to improve the performance of high-resolution atmospheric models (Pichelli et al, 2010). Besides meteorology, GNSS estimates of PWV have been employed over Scandinavia for climatological research (Elgered and Jarlemark, 1998;Gradinarsky et al, 2002;Nilsson and Elgered, 2008). The authors found that PWV shows an increase of 1.2-2.4 mm decade −1 .…”

Section: Introductionmentioning

confidence: 98%

Estimating trends in atmospheric water vapor and temperature time series over Germany

Alshawaf

Balidakis²,

Dick

et al. 2017

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. Ground-based GNSS (Global Navigation Satellite System) has efficiently been used since the 1990s as a meteorological observing system. Recently scientists have used GNSS time series of precipitable water vapor (PWV) for climate research. In this work, we compare the temporal trends estimated from GNSS time series with those estimated from European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-Interim) data and meteorological measurements. We aim to evaluate climate evolution in Germany by monitoring different atmospheric variables such as temperature and PWV. PWV time series were obtained by three methods: (1) estimated from ground-based GNSS observations using the method of precise point positioning, (2) inferred from ERA-Interim reanalysis data, and (3) determined based on daily in situ measurements of temperature and relative humidity. The other relevant atmospheric parameters are available from surface measurements of meteorological stations or derived from ERA-Interim. The trends are estimated using two methods: the first applies least squares to deseasonalized time series and the second uses the Theil-Sen estimator. The trends estimated at 113 GNSS sites, with 10 to 19 years temporal coverage, vary between −1.5 and 2.3 mm decade −1 with standard deviations below 0.25 mm decade −1 . These results were validated by estimating the trends from ERA-Interim data over the same time windows, which show similar values. These values of the trend depend on the length and the variations of the time series. Therefore, to give a mean value of the PWV trend over Germany, we estimated the trends using ERA-Interim spanning from 1991 to 2016 (26 years) at 227 synoptic stations over Germany. The ERA-Interim data show positive PWV trends of 0.33 ± 0.06 mm decade −1 with standard errors below 0.03 mm decade −1 . The increment in PWV varies between 4.5 and 6.5 % per degree Celsius rise in temperature, which is comparable to the theoretical rate of the ClausiusClapeyron equation.

show abstract

Section: Introductionmentioning

confidence: 98%

Estimating trends in atmospheric water vapor and temperature time series over Germany

Alshawaf

Balidakis²,

Dick

et al. 2017

Atmos. Meas. Tech.

View full text Add to dashboard Cite

show abstract

“…During CONT08 three WVRs were operated at VLBI sites: the Astrid radiometer at Onsala (Elgered and Jarlemark, 1998), as well as the Radiometrix radiometers at Wettzell and Tsukuba.…”

Section: Water Vapor Radiometer (Wvr)mentioning

confidence: 99%

Multi-technique comparison of troposphere zenith delays and gradients during CONT08

Teke

Boehm

Nilsson

et al. 2011

J Geod

View full text Add to dashboard Cite

“…Because microwave radiometers are robust technology and need little maintenance, long-term time series of LWP and IWV can be derived from them at single stations [Güldner and Spänkuch, 1999;Elgered and Jarlemark, 1998;Snider, 2000]. While IWV can be validated with colocated measurements from other sensors such as radiosondes, GPS, and Raman lidar, assessment of LWP retrievals is harder to perform.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of cloud liquid water path from ground‐based microwave radiometry 2. Sensor accuracy and synergy

2003

View full text Add to dashboard Cite

[1] The influence of microwave radiometer accuracy on retrieved cloud liquid water path (LWP) was investigated. Sensor accuracy was assumed to be the sum of the relative (i.e., Gaussian noise) and the absolute accuracies of brightness temperatures. When statistical algorithms are developed the assumed noise should be as close as possible to the real measurements in order to avoid artifacts in the retrieved LWP distribution. Typical offset errors of 1 K in brightness temperatures can produce mean LWP errors of more than 30 g m À2 for a two-channel radiometer retrieval, although positively correlated brightness temperature offsets in both channels reduce this error to 16 g m À2 . Large improvements in LWP retrieval accuracy of about 50% can be achieved by adding a 90-GHz channel to the two-channel retrieval. The inclusion of additional measurements, like cloud base height from a lidar ceilometer and cloud base temperature from an infrared radiometer, is invaluable in detecting cloud free scenes allowing an indirect evaluation of LWP accuracy in clear sky cases. This method was used to evaluate LWP retrieval algorithms based on different gas absorption models. Using two months of measurements, the Liebe 93 model provided the best results when the 90-GHz channel was incorporated into the standard two-channel retrievals.INDEX TERMS: 3360 Meteorology and Atmospheric Dynamics: Remote sensing; 3394 Meteorology and Atmospheric Dynamics: Instruments and techniques; 6969 Radio Science: Remote sensing; 1640 Global Change: Remote sensing; 1655 Global Change: Water cycles (1836); KEYWORDS: microwave radiometer, cloud liquid water, sensor synergy, ground-based remote sensing Citation: Crewell, S., and U. Löhnert, Accuracy of cloud liquid water path from ground-based microwave radiometry, 2, Sensor accuracy and synergy,

show abstract

Ground‐based microwave radiometry and long‐term observations of atmospheric water vapor

Cited by 40 publications

References 22 publications

Estimating trends in atmospheric water vapor and temperature time series over Germany

Estimating trends in atmospheric water vapor and temperature time series over Germany

Multi-technique comparison of troposphere zenith delays and gradients during CONT08

Accuracy of cloud liquid water path from ground‐based microwave radiometry 2. Sensor accuracy and synergy

Contact Info

Product

Resources

About