Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Characteristics and Effects of Ground-Based GNSS Zenith Total Delay Observation Errors in the Convective-Scale Model
Eun-Hee KIMEunhee LEESeung-Woo LEEYong Hee LEE
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JOURNALS FREE ACCESS Advance online publication

Article ID: 2019-056

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Abstract

 In this study, we evaluated the impacts of revised observation error on ground-based global navigation satellite system (GNSS) zenith total delay (ZTD) data in the data assimilation system of the Korea Meteorological Administration 1.5 km convective-scale model. Out of 100 total stations on the Korean Peninsula, 40 ground-based GNSS data stations were assimilated using three-dimensional variational (3D-Var) data assimilation. The ZTD observation errors were diagnosed for each station using a posteriori methods, giving errors with a variety of spatial and temporal characteristics. These station-specific error data were then implemented using the data assimilation system, and their impacts were evaluated for a one-month period in July 2016.

 The root-mean-square error (RMSE) of the relative humidity in the lower troposphere was found to be improved for the period from T+0 to T+36 hours when using GNSS data. Replacing the errors used in the previous model with the average diagnosed errors also provided better results, but they were not as good as the results obtained using station-specific errors. We found that observation error is closely related to precipitable water vapor (PWV); therefore, correction values reflecting seasonal characteristics should be applied. In addition, the quantitative precipitation forecasts were improved in all experiments using GNSS data, although the effects were small.

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© The Author(s) 2019. This is an open access article published by the Meteorological Society of Japan under a Creative Commons Attribution 4.0 International (CC BY 4.0) license.
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