A Novel Approach for the Determination of the Height of the Tropopause from Ground-Based GNSS Observations

Changes in the tropopause can explain regional and global weather and climate. In Tibet, there are few radiosonde stations, and the detection height is not high enough. Radio occultation (RO) data are insufficient because of the small regional scale, which is not conducive to the analysis of tropopause change.Moreover, in some middle and high latitudes, it was more difficult to identify the tropopause height from the temperature profile. In this study, an improved method has been developed for the inversion of the tropical tropopause based on a ground-based global navigation satellite system (GNSS) network combined with reanalysis data. Using zenith tropospheric delay data from 49 GNSS reference stations in Tibet from January 2017 to December 2019, combined with ERA5 reanalysis, the tropical tropopause (TPH) was successfully inversed, its temporal and spatial distribution is analysed, and compared with ERA5-derived TPH obtained by the temperature profile of the interpolated co-site points. In more than 90% of cases, the difference between the two is <2 km. The root mean square of the tropopause difference detected by GNSS-derived TPH and RO-derived TPH was ±1.25 km; the accuracies were at the same level. By combining the tropopause obtained from ground-based GNSS and that from spacebased RO, temporal and spatial changes in the tropopause were analysed. The tropopause in Tibet has a latitude-zoning distribution with obvious unimodal seasonal changes. Monthly changes excluding seasonal variation indicate a slight downward trend from 2017 to 2019. At the same time, changes in the tropopause are closely related to those in weather and climate. The results of this study confirm that the combination of ground-based GNSS and space-based RO can realize long-term, continuous, and full coverage monitoring of the regional tropopause. This expands the application possibilities of ground-based GNSS.

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“…The integral is calculated from the geopotential height

{Z}_{\mathrm{site}}

where the receiver is located at the tropopause

{Z}_{\mathrm{trop}}

{Z}_{\mathrm{trop}}

defines the atmosphere that causes the tropospheric delay of the GNSS signal and corresponds to the second tropopause height (Astudillo et al, 2020).

{\mathrm{ZHD}}_{\mathrm{trop}}

represents the ZHD above the tropopause.…”

Section: Methodsmentioning

confidence: 99%

“…Compared with the method of Astudillo et al(2020), we consider the influence of ZHD above the tropopause. 80% of the tropospheric delay occurs in the troposphere (Ding, 2009), and the remaining 20% is non‐negligible.…”

Section: Methodsmentioning

confidence: 99%

Tropical tropopause in Tibet: Insights from ground‐based global navigation satellite system and space‐based radio occultation observations

Jiang

Shan

Guo

et al. 2022

Meteorological Applications

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“…The BDS [23] constellation consists of Geostationary Earth Orbit (GEO) satellites, Inclined GeoSynchronous Orbit (IGSO) satellites, and Medium Earth Orbit (MEO) satellites. The orbit altitudes of GEO, IGSO, and MEO satellites are 35,786,35,786, and 21,528 km respectively.…”

Section: Bds Signal Characteristicsmentioning

confidence: 99%

“…Moreover, the various integrated quantities (zenith total delay, precipitable water vapor, etc.) in the atmosphere can also be retrieved by the ground-based GNSS observations using the precise point positioning technique [33][34][35]. Since tropospheric ducts have fewer impacts on the satellite signals at high elevation angles and cause serious multipath effects at low elevation angles, GNSS tomography and single ground-based GNSS retrieval are unsuitable for monitoring tropospheric ducts.…”

Section: Introductionmentioning

confidence: 99%

Inversion for Inhomogeneous Surface Duct without a Base Layer Based on Ocean-Scattered Low-Elevation BDS Signals

Liu

Cao

et al. 2021

Remote Sensing

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The anomalous propagation conditions, particularly the tropospheric ducts, severely impact the regular operation and performance evaluation of radio devices in the atmospheric boundary layer. Therefore, it is necessary to provide the regional distribution of tropospheric ducts for utilizing or avoiding these abnormal propagation phenomena. As significant uncooperative signal sources, the global navigation satellite systems (GNSS) have been widely applied in the remote sensing of the ocean and atmosphere due to the greater convenience and lower cost. With the completed deployment of the BeiDou Navigation Satellite System (BDS) in 2020, an additional source can be chosen in the relevant studies. Taking the BDS as an example, since the scattered signals from the ocean surface at low satellite elevation angles can be effectively trapped by tropospheric ducts, we propose a method to invert for the regional distribution of tropospheric ducts using the received power of ocean-scattered signals in this paper. Firstly, the propagation model was built to calculate the received power, and a suite of simulations was made in various atmospheric environments. The results suggested that the received power is more sensitive to the surface duct without a base layer. Then, we made a preliminary estimation of the tropospheric ducts on the ocean nearby Qingdao utilizing the Weather Research and Forecasting (WRF) model as well as the echo data measured by a Doppler weather radar. Before the inversion, the actual satellite azimuth and elevation angles should be obtained to evaluate the bistatic scattering coefficients and the received powers of the selected satellite signals. Finally, we presented an inversion example using the proposed method. In absence of the actual measurements, the received powers pre-estimated at different SNRs served as the inputs of the inversion process and the estimated duct parameters were used to verify the validity of the proposed inversion method. For both the received power and modified refractivity profile, the fitness between the values pre-estimated using the estimated duct parameters and calculated by the inverted duct parameters gets better as the elevation angle decreases and the SNR increases. The variation of the fitness between the estimated and inverted values is slightly different for each duct parameter. Moreover, the calculation of inversion errors further explained the above behaviors, including the mean absolute error (MAE) and the root mean square error (RMSE). Despite some certain errors, the inversion results maintain the overall tendencies and most characteristics of the estimated values, thus proving the validity of the inversion method.

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“…It requires the profile of the refractivity previously obtained with radiosonde data, N0 and Nh are needed as inputs (defined in Section 1). The ZTD is also an input into the following equation [25].…”

Section: Height Of the Troposphere (S)mentioning

confidence: 99%

Urban Heat Island Monitoring with Global Navigation Satellite System (GNSS) Data

Méndez-Astudillo

Lau

Lun

et al. 2020

Advances in 21st Century Human Settlements

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The Urban Heat Island (UHI) effect occurs when the temperature in an urban area is higher than the temperature at a rural area. UHIs are monitored using remote sensing techniques such as satellite imagery or using temperature sensors deployed in a metropolitan area. In this chapter we propose a methodology to monitor the UHI intensity from Global Navigation Satellite Systems (GNSS) data. As the GNSS signal travels from the satellite to the receiver it propagates through the troposphere. A delay (Tropospheric delay) affects the signal. The delay is proportional to environmental variables. Also, the tropospheric delay in zenith direction (ZTD) is estimated as part of the Precise Point Positioning (PPP) technique. Therefore, in this chapter it is shown how to use process GNSS data to obtain ZTD and obtain temperature at an urban and a rural site simultaneously from the ZTD. The advantages of using GNSS data is its availability and many GNSS networks have been deployed in different cities so no need to deploy sensor networks. Furthermore, GNSS signal is less affected by bad weather conditions than satellite imagery.

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A Novel Approach for the Determination of the Height of the Tropopause from Ground-Based GNSS Observations

Cited by 4 publications

References 26 publications

Tropical tropopause in Tibet: Insights from ground‐based global navigation satellite system and space‐based radio occultation observations

Tropical tropopause in Tibet: Insights from ground‐based global navigation satellite system and space‐based radio occultation observations

Inversion for Inhomogeneous Surface Duct without a Base Layer Based on Ocean-Scattered Low-Elevation BDS Signals

Urban Heat Island Monitoring with Global Navigation Satellite System (GNSS) Data

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