GPS meteorology and the phenomenology of precipitable water

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Thesis (Ph. D.)--University of Hawaii at Manoa, 2002. Mode of access: World Wide Web. Includes bibliographical references (leaves 62-66). Electronic reproduction. Also available by subscription via World Wide Web ix, 66 leaves, bound ill. 29 cm Three studies of precipitable water using the Global Positioning System are presented. The first study finds that precipitable water in Hawaiʻi is best described by a lognormal distribution. The long-term average value of precipitable water declines exponentially with height, but the dispersion of precipitable water declines more linearly. The change in skewness of the distributions is also linear, although in this case it increases with elevation. The second and third studies use GPS meteorology to investigate a climatological and a meteorological event respectively. First, the effect of the 1997-1998 El Nino on precipitable water in the western tropical Pacific is studied and found to be consistent with a model relating the formation of an anomalous high-pressure ridge to the El Nino episode. Finally, the details of the precipitable water field for the Kaʻu Storm, November 2000 are examined. The results highlight the role of topography in controlling the location of convection, The observed correlation between the precipitable water and rainfall is used to generate estimates of rainfall based on GPS data, Comparing the GPS precipitable water estimates with those from a weather model indicates that the underestimates of rainfall produced by the weather model are probably due to correlated underestimates of precipitable water. PhD

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Available from: James Foster, Oct 02, 2015
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    ABSTRACT: Observational evidence is presented to show a teleconnection between the central Pacific and East Asia during the extreme phases of ENSO cycles. This Pacific-East Asian teleconnection is confined to the lower troposphere. The key system that bridges the warm (cold) events in the eastern Pacific and the weak (strong) East Asian winter monsoons is an anomalous lower-tropospheric anticyclone (cyclone) located in the western North Pacific. The western North Pacific wind anomalies develop rapidly in late fall of the year when a strong warm or cold event matures. The anomalies persist until the following spring or early summer, causing anomalously wet (dry) conditions along the East Asian polar front stretching from southern China northeastward to the east of Japan (Kuroshio extension).Using atmospheric general circulation and intermediate models, the authors show that the anomalous Philippine Sea anticyclone results from a Rossby-wave response to suppressed convective heating, which is induced by both the in situ ocean surface cooling and the subsidence forced remotely by the central Pacific warming. The development of the anticyclone is nearly concurrent with the enhancement of the local sea surface cooling. Both the anticyclone and the cooling region propagate slowly eastward. The development and persistence of the teleconnection is primarily attributed to a positive thermodynamic feedback between the anticyclone and the sea surface cooling in the presence of mean northeasterly trades. The rapid establishment of the Philippine Sea wind and SST anomalies implies the occurrence of extratropical-tropical interactions through cold surge-induced exchanges of surface buoyancy flux. The central Pacific warming plays an essential role in the development of the western Pacific cooling and the wind anomalies by setting up a favorable environment for the anticyclone-SST interaction and midlatitude-tropical interaction in the western North Pacific.
    Journal of Climate 05/2000; 13(9):1517-1536. DOI:10.1175/1520-0442(2000)013<1517:PEATHD>2.0.CO;2 · 4.44 Impact Factor
  • Monthly Weather Review 07/1977; 105(7). DOI:10.1175/1520-0493(1977)105<0865:TLDACC>2.0.CO;2 · 3.36 Impact Factor
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    ABSTRACT: We present GPS, radiosonde and microwave radiometer (MWR) estimates of precipitable water vapor (PW) at Cape Grim, Tasmania, during November and December 1995. The rms differences between GPS and radiosonde, MWR and radiosonde and GPS and MWR estimates of PW were 1.5 mm, 1.3 mm and 1.4 mm, respectively, whilst the biases between the three systems were ~0.2 mm. However, there are occasions when the amount of PW was under-estimated by GPS whilst at other times was over-estimated by MWR. The average overlap error of the GPS estimates of PW between adjacent daily solutions is related to the orbit overlap error and we removed a 2 mm bias introduced using International GPS Service orbits by estimating more accurate global orbits. The discrepancies of up to 3-4 mm between the MWR and GPS systems are not caused by rain, waveguide losses, varying waveguide temperature, detector non-linearity or inaccurate estimates of the mean radiating temperature of the atmosphere. However, small differences between mapping functions at low elevations can produce biases comparable with the bias between the two systems. Consequently, we suspect that the biases arise because the mapping functions do not represent the localized atmospheric conditions at Cape Grim. The most accurate GPS estimates are achieved when the GPS analysis contains station separations of more than 2000 km, an elevation cutoff angle of 12° is used and the CFA2.2 wet mapping function is used to map the wet delay at any angle to the delay in the zenith.
    Journal of Geophysical Research Atmospheres 11/1998; 1032(D22):28701-28710. DOI:10.1029/98JD02516 · 3.43 Impact Factor
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