Tropical cyclone-induced periodical positioning disturbances during the 2017 Hato in the Hong Kong region

Abstract

The tropospheric delay is an important error source in the Global Positioning System (GPS) positioning and navigation applications. Although most of the tropospheric delays can be removed in the double-differencing (DD) positioning mode, their remaining residuals can still contaminate the positioning accuracy and become unpredictable when tropospheric condition encounters severe variations such as during a tropical cyclone (TC) event. We investigated the positioning performance of five baselines with lengths ranging from 7.8 km to 49.9 km during the 2017 TC Hato. The results showed that the TC Hato brought a significant disturbance to the GPS baseline positioning results, particularly in the vertical (up) component. The TC Hato started to affect Hong Kong and the root mean squares (RMS) of GPS positioning errors increased dramatically from about 30 mm to 140 mm.when it was at a distance of 400-600 km from Hong Kong on August 22, 2017. We found that the vertical positioning errors on that day have the major periods: 2.7 h, 3.0 h, 3.4 h, 4.0 h, and 4.8 h.Examining the wet and hydrostatic parts of the tropospheric delays via the continuous wavelet spectral analysis, we found that the periodical variation of the positioning results on August 22 was caused by the periodical variation of the precipitable water vapor (PWV). The variation of differenced PWV between two baseline stations had consistent periods of 2-5 h. Besides, the periods of differenced PWV time series are in good agreement with the spiral rainband in the TC. This finding suggests that the TC Hato induce periodical PWV variations at two GPS stations of baseline, which resulted in GPS positioning errors of the same periods.

A two-step non-nominal troposphere monitor for GBAS

“…In this paper, the delays caused by the troposphere spatial decorrelation is defined as the non-nominal troposphere. According to the present regularity, various troposphere spatial decorrelation events have been observed in local atmospheric abnormal activities (Lawrence et al 2006;Huang and Graas 2007;Guilbert et al 2017;Yu and Liu 2021). For example, an extreme troposphere spatial decorrelation event of approximately 0.4m is observed at the baseline of 5 km in Ohio (Huang et al 2008), which is unacceptable for high-precision navigation.…”

“…where 2 t  is the test statistic noise whose standard deviation is approximately three times larger than that of ionosphere-based test statistics proposed by Yu and Liu (2021). It can be found that the test statistic t2 trades the decorrelation monitoring ability by losing part of the measurement accuracy.…”

“…The typical troposphere spatial decorrelation events are characterized for three different areas, Stennis, Raleigh, and Hong Kong based on GNSS dual-frequency post-processing results (Lawrence et al 2006;Huang and Graas 2007;Yu and Liu 2021). A detailed description of the data such as baseline length, collection time and sampling rate is given in Table 1.…”

Variation Trends of Asymmetrical Precipitable Water Vapor Outside the Tropical Cyclone Center Over the WNP and WSP Ocean

“…However, little research pertaining to the water vapor during the TC events has been carried out. Precipitable water vapor (PWV) is one of important sources for rainfalls and clouds (Bretherton et al., 2004; Lavender & McBride, 2021; S. Yu & Liu, 2021) and one of the critical driving forces for TC genesis and evolution (Mure‐Ravaud, Dib, et al., 2019; Mure‐Ravaud, Ishida, et al., 2019). Accurate PWV information can help increase the probability of detecting TC's genesis (Ejigu et al., 2021; S.‐Y.…”