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Comparative Analysis of Annual Tropospheric Delay by Season and Weather

계절과 날씨에 따른 연간 대류권 지연오차량 변화

  • Lim, Soo-Hyeon (Dept. Environment, Energy & Geoinformatics, Sejong University) ;
  • Kim, Ji-Won (Dept. Environment, Energy & Geoinformatics, Sejong University) ;
  • Park, Jeong-Eun (Dept. Environment, Energy & Geoinformatics, Sejong University) ;
  • Bae, Tae-Suk (Dept. Environment, Energy & Geoinformatics, Sejong University) ;
  • Hong, Sungwook (Dept. Environment, Energy & Geoinformatics, Sejong University)
  • Received : 2018.12.07
  • Accepted : 2018.12.17
  • Published : 2019.02.28

Abstract

In this study, we estimated the tropospheric delay of GNSS (Global Navigation Satellite System) signals during passing through the atmosphere in relation to weather and seasonal factors. For this purpose, we chose four CORS (Continuously Operating Reference Station) stations from inland (CCHJ and PYCH) and on the coast (GEOM and CHJU). A total of 48 days for each station (one set of data for each week) were downloaded from the NGII (National Geographic Information Institute) and processed it using the scientific GNSS software. The average tropospheric delays in winter are less than 2,400 mm, which is about 200 mm less than those in summer. The estimated tropospheric delay shows a similar pattern from all stations except the absolute bias in magnitude, while a large delay was observed for the station located on the coast. In addition, the delay during the day was relatively stable in winter, and the average tropospheric delay was strongly related to the orthometric height. The inland stations have tropospheric delays by the precipitation rather than humidity due to dry weather and difference in temperature. On the contrary, it was primarily caused by the humidity on the sea. The correlation between temperature and water vapor pressure is 0.9 or larger for all stations, and the tropospheric delay showed a high linear relationship with temperature. It is necessary to analyze the GNSS data with higher temporal resolution (e.g. all RINEX data of the year) to improve the stability and reliability of the correlation results.

본 연구에서는 GNSS (Global Navigation Satellite System) 신호가 전송되는 동안 발생하는 오차 중 대류권 지연오차를 추정하고, 이를 날씨 및 계절별 요소와 비교 분석했다. 이를 위해, 내륙지역인 충주와 평창, 해안지역인 제주, 거문도의 총 4개의 상시관측소를 선정하고, 2016년 중 매주 하루씩, 각 상시관측소마다 총 48일의 데이터를 이용하여 과학기술용 자료처리 소프트웨어로 정밀절대측위를 수행했다. 겨울철 대류권 지연오차는 평균 2400mm 미만으로, 2600mm 수준인 여름의 경우와 비교했을 때 약 200mm 가량 차이가 발생했다. 추정한 대류권 지연오차는 절대적인 지연량의 차이를 제외하면 모든 상시관측소에 대해서 변화 양상이 비슷하며, 해안지역의 지연오차가 상대적으로 크게 나타났다. 또한, 겨울에는 24시간 대류권 지연오차의 변화량이 상대적으로 적으며, 평균적인 대류권 지연오차는 상시관측소의 표고와 직접적인 관계가 있는 것으로 나타났다. 건조하고 온도 차이가 큰 내륙지역에서는 습도보다 강수량에 영향을 받은 대류권 지연오차의 변화가 발생하고, 다습한 해안지역에서는 강수보다 바다의 습도로 인한 변화가 큰 것으로 판단된다. 온도와 증기압의 상관계수는 모든 지역에서 0.9 이상을 나타냈으며, 대류권 지연오차는 온도와 높은 선형적 상관성을 보였다. 향후 연간 데이터 전체를 이용하여 시간적 해상도를 높인 연구분석을 수행함으로써 보다 신뢰도 높은 상관성 분석이 이루어질 필요가 있다.

Keywords

GCRHBD_2019_v37n1_1_f0001.png 이미지

Fig. 1. Location map of CORS used in this study

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Fig. 2. Zenith Total Delay in summer (July)

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Fig. 3. Zenith Total Delay in winter (December)

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Fig. 4. Annual variation of ZTD (Year 2016)

GCRHBD_2019_v37n1_1_f0005.png 이미지

Fig. 5. Relationship between annual precipitation and humidity for each station

Table 1. Height information for all stations used in the study. The orthometric heights refer to the ARP (Antenna Reference Point)

GCRHBD_2019_v37n1_1_t0001.png 이미지

Table 2. Correlation between ZTD and weather components

GCRHBD_2019_v37n1_1_t0002.png 이미지

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