A High-Resolution, Precipitable Water Vapor Monitoring System Using a Dense Network of GNSS Receivers
Kazutoshi Sato*,**, Eugenio Realini*, Toshitaka Tsuda*,
Masanori Oigawa*, Yuya Iwaki*, Yoshinori Shoji***,
and Hiromu Seko***
*Research Institute for Sustainable Humanosphere (RISH), Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
**Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
***Meteorological Research Institute (MRI), Japan Meteorological Agency (JMA), 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan
This work describes a system aimed at the near realtimemonitoring of precipitable water vapor (PWV) by means of a dense network of Global Navigation Satellite System (GNSS) receivers. These receivers are deployed with a horizontal spacing of 1-2 km around the Uji campus of Kyoto University, Japan. The PWV observed using a standard GPS meteorology technique, i.e., by using all satellites above a low elevation cutoff, is validated against radiosonde and radiometer measurements. The result is a RMS difference of about 2 mm. A more rigorous validation is done by selecting single GPS slant delays as they pass close to the radiosonde or the radiometer measuring directions, and higher accuracy is obtained. This method also makes it possible to preserve short-term fluctuations that are lost in the standard technique due to the averaging of several slant delays. Geostatistical analysis of the PWV observations shows that they are spatially correlated within the area of interest; this confirms that such a dense network can detect inhomogeneous distributions in water vapor. The PWV horizontal resolution is improved by using high-elevation satellites only, with the aim of exploiting at best the future Quasi-Zenith Satellite System (QZSS), which will continuously provide at least one satellite close to the zenith over Japan.
-  M. Bevis, S. Businger, T. A. Herring, C. Rocken, R. A. Anthes, and R. H. Ware, “GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System,” Journal of Geophysical Research, 97(D14), 15, pp. 787-15,801, 1992.
-  H. Nakamura, K. Koizumi, and N. Mannoji, “Data assimilation of GPS precipitable water vapor into the JMA mesoscale numerical weather prediction model and its impact on rainfall forecast,” Journal of the Meteorological Society of Japan, 82, pp. 441-452, 2004.
-  K. Koizumi and Y. Sato, “Impact of GPS and TMI precipitable water data on mesoscale numerical weather prediction model forecasts,” Journal of the Meteorological Society of Japan, 82, pp. 453-457, 2004.
-  H. Seko, T. Kawabata, T. Tsuyuki, H. Nakamura, K. Koizumi, and T. Iwabuchi, “Impacts of GPS-derivedWater vapor and RadialWind measured by Doppler radar on Numerical Prediction of Precipitation,” Journal of the Meteorological Society of Japan, 82, pp. 473-489, 2004.
-  Y. Ishikawa, “The Use of Ground Based GPS Data for Meso-scale Analysis,” Suuchi Yohouka Houkoku Bessatsu (Additional Volume to Report of Numerical Prediction Division), 56, pp. 54-60, 2010 (in Japanese).
-  Y. Shoji, H. Seko, T. Iwabuchi, and H. Nakamura, “A case study of water vapor variation in a severe thunderstorm in Tokyo by using dense network of GPS,” Proceedings of International Conference on Mesoscale Convective Systems and Heavy Rain in East Asia Tokyo, 2002.
-  H. Seko, H. Nakamura, Y. Shoji, and T. Iwabuchi, “The Meso-γ scale Water Vapor Distribution Associated with a Thunderstorm Calculated from a Dense Network of GPS Receivers,” Journal of the Meteorological Society of Japan, 82(1B), pp. 569-586, 2004.
-  Y. Shoji, “A study of Near Real-time Water Vapor Analysis Using a Nationwide Dense GPS Network of Japan,” Journal of the Meteorological Society of Japan, 87, pp. 1-18, 2009.
-  A. Hauschild and O. Montenbruck, “Real-time Clock Estimation for Precise Orbit Determination of LEO-Satellites,” ION GNSS 2008 Conference, Savannah, Georgia, 16-19 Sept. 2008.
-  J. Boehm, A. E. Niell, P. Tregoning, and H. Schuh, “Global Mapping Functions (GMF): A new empirical mapping function based on numerical weather model data,” Geoph. Res. Letters, 33, L07304, doi:10.1029/2005GL025545, 2006.
-  J. Saastamoinen, “Atmospheric correction for the troposphere and stratosphere in radio ranging satellites,” Use of artificial satellites for geodesy, Geophysics Monograph Series, 15, pp. 247-251, 1972.
-  J. Saastamoinen, “Contribution to the theory of atmospheric refraction, Bulletin Géodésique, Vol.107, No.1, pp. 13-34, 1973.
-  J. Askne and H. Nordius, “Estimation of tropospheric delay for microwaves from surface weather data,” Radio Science, 22, pp. 379-386, 1987.
-  Y. Shoji, PhD thesis, Kyoto University, 2010.
-  G. Matheron, “Principles of geostatistics,” Economic Geology, 58, pp. 1246-1266, 1963.
-  H. Wackernagel, “Multivariate Geostatistics: an Introduction with Applications,” Springer, Berlin, 2003.
-  M. Reguzzoni, G. Venuti, and F. Sansò, “The theory of general kriging, with applications to the determination of a local geoid,” Geophysical Journal International, 162, pp. 303-314, 2005.
-  N. Cressie, “The Origins of Kriging,” Mathematical Geology, Vol.22, No.3, pp. 239-252, 1990.
-  L. S. Gandin, “Objective analysis of meteorological fields: Gidrometeorologicheskoe Izdatel’stvo (GIMIZ),” Leningrad, 1963 (translated by the Israel Program for Scientific Translations, Jerusalem, 1965).