Global Positioning System Project to improve Japanese Weather, earthquake predictions

Naito, Isao; Hatanaka, Yuki; Mannoji, Nobutaka; Ichikawa, Ryuichi; Shinji, Seiichi; Yabuki, Taisei; Tsuji, Hiromichi; Tanaka, T.

doi:10.1029/98eo00222

Cited by 15 publications

(9 citation statements)

References 7 publications

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“…Recent investigations concentrate on the possible use of dense permanent GPS networks as multi-purpose networks providing estimates of atmospheric parameters for weather monitoring and prediction (see, e.g. Naito et al, 1998). In order to verify the results for atmospheric parameters derived from the GPS observations it is necessary to compare them to data from independent measurement techniques.…”

Section: Introductionmentioning

confidence: 99%

Wet path delay and delay gradients inferred from microwave radiometer, GPS and VLBI observations

et al. 2014

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Very Long Baseline Interferometry (VLBI) is collocated with a permanent Global Positioning System (GPS) receiver and a Water Vapor Radiometer (WVR) at the Onsala Space Observatory in Sweden. Both space geodetic techniques are affected by the propagation delay of radio waves in the atmosphere, while the remote sensing technique is sensitive to the atmospheric emission close to the center of the 22 GHz water vapor emission line. We present a comparison of estimated equivalent zenith wet delay and linear horizontal delay gradients from an independent analysis of simultaneous VLBI, GPS, and WVR observations. Using different constraints for the variability of the delay and the horizontal gradient in the analysis of the VLBI and the GPS data did not have a large influence on the agreement with the WVR estimates. We found that the weighted rms differences between wet delay estimates from the geodetic techniques and the WVR estimates generally increased for an increased variability in the atmosphere.

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Section: Introductionmentioning

confidence: 99%

Wet path delay and delay gradients inferred from microwave radiometer, GPS and VLBI observations

et al. 2014

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“…It has been shown that including more detailed atmospheric moisture data, such as observed total-column precipitable water vapor [hereinafter referred to as precipitable water vapor (PWV)], in numerical model assimilation schemes generally improves model forecast skill (e.g., Naito et al 1998;Gutman and Benjamin 2001;Vedel and Huang 2004). The operational use of surfacebased atmospheric microwave radiometers (e.g., Lesht and Liljegren 1997;Knupp et al 2008) and GPS receivers (e.g., Deblonde et al 2005;Wang and Zhang 2009) now makes it possible to verify a forecast model's atmospheric water vapor field over diurnal temporal scales.…”

Section: Introductionmentioning

confidence: 99%

Observed and Modeled Growing-Season Diurnal Precipitable Water Vapor in South-Central Canada

Hanesiak

Melsness

Raddatz

2010

Journal of Applied Meteorology and Climatology

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High-temporal-resolution total-column precipitable water vapor (PWV) was measured using a Radiometrics Corporation WVR-1100 Atmospheric Microwave Radiometer (AMR). The AMR was deployed at the University of Manitoba in Winnipeg, Canada, during the 2003 and 2006 growing seasons (mid-May-end of August). PWV data were examined 1) to document the diurnal cycle of PWV and to provide insight into the various processes controlling this cycle and 2) to assess the accuracy of the Canadian regional Global Environmental Multiscale (GEM) model analysis and forecasts (out to 36 h) of PWV. The mean daily PWV was 22.6 mm in 2003 and 23.8 mm in 2006, with distinct diurnal amplitudes of 1.5 and 1.8 mm, respectively. It was determined that the diurnal cycle of PWV about the daily mean value was controlled by evapotranspiration (ET) and the occurrence/timing of deep convection. The PWV in both years reached its hourly maximum later in the afternoon as opposed to at solar noon. This suggested that the surface and atmosphere were well coupled, with ET primarily being controlled by the vapor pressure deficit between the vegetation/surface and atmosphere. The decrease in PWV during the evening and overnight periods of both years was likely the result of deep convection, with or without precipitation, which drew water vapor out of the atmosphere, as well as the nocturnal decline in ET. The results did not change for days on which low-level winds were light (i.e., maximum winds from the surface to 850 hPa were below 20 km h 21 ), which supports the notion that the diurnal PWV pattern was associated with the daily cycles of local ET and convection/precipitation and was not due to advection. Comparison of AMR PWV with the Canadian GEM model for the growing seasons of 2003 and 2006 indicated that the model error was 3 mm (13%) or more even in the first 12 h, with mean absolute errors ranging from 2 to 3.5 mm and root-mean-square errors from 3 to 4.5 mm over the full 36-h forecast period. It was also found that the 3-9-h forecast period of GEM had better error scores in 2006 than in 2003.

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“…The spatiotemporal distribution of tropospheric water vapor is highly variable in summer over the Japanese Islands [e.g., Naito et al , 1998; Iwabuchi et al , 2000] and cannot be properly modeled by a mapping function assuming azimuthal symmetry of the water vapor distribution [e.g., Niell , 1996]. It is hence likely that the fluctuation in GPS time series in summer is due to the deviation of the atmosphere from this idealized state, and it is important to know how and to what extent site coordinates are affected by the unmodeled anisotropy of water vapor distribution.…”

Section: Introductionmentioning

confidence: 99%

An impact of estimating tropospheric delay gradients on precise positioning in the summer using the Japanese nationwide GPS array

et al. 2003

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[1] We investigate the effect of modeling tropospheric delay gradients on the station position estimates using the Japanese nationwide GPS array. The time series shows spatially coherent temporal fluctuations due to the variability of water vapor distribution. This makes it difficult to identify small crustal deformation signals in GPS time series. Precision and accuracy of station positions are known to be improved by modeling the tropospheric delay gradient, and past studies suggest that delay gradient estimates agree well with the collocated water vapor radiometer measurements. Here we pick up two intervals as long as 2 weeks in 1996 summer, when remarkable tropospheric delay gradients are expected, and investigate various influences of tropospheric delay gradients on station position estimates. First, we study spatial patterns of station position deviations caused by azimuthal asymmetry of water vapor distributions from two solutions, i.e., with and without the tropospheric delay gradient model. Second, we compare them with the estimated delay gradients. Site coordinate deviations in the solution without the delay gradient model are negatively correlated with the estimated delay gradients, but such systematic deviations disappear by introducing the delay gradient model. We found that the improvement in position accuracy is significant not only horizontally but also vertically over both of the two time intervals.

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Global Positioning System Project to improve Japanese Weather, earthquake predictions

Cited by 15 publications

References 7 publications

Wet path delay and delay gradients inferred from microwave radiometer, GPS and VLBI observations

Wet path delay and delay gradients inferred from microwave radiometer, GPS and VLBI observations

Observed and Modeled Growing-Season Diurnal Precipitable Water Vapor in South-Central Canada

An impact of estimating tropospheric delay gradients on precise positioning in the summer using the Japanese nationwide GPS array

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