Modelling of weighted-mean temperature using regional radiosonde observations in Hunan China

Abstract

Precipitable water vapour (PWV) over a ground station can be estimated from the global navigation satellite systems (GNSS) signal's zenith wet delays (ZWD) multiplying by a conversion factor that is a function of weighted-mean temperature (T m). The commonly used Bevis T m model (BTM) may not perform well in some regions due to its use of data from North America in the model development. In this study, radiosonde observations in 2012 from three stations-Changsha, Huaihua, Chenzhou in Hunan province, China-were used to establish a new regional T m model (RTM) based on a numerical integration and the least squares estimation methods. Four seasonal RTMs were also established and assessed for 2012. The RTM-derived T m at the three stations from 2012-2014 were validated by comparing it with radiosondederived T m. Results showed that the accuracy of the yearly RTM was improved by 29% over the BTM, and the bias and root mean square (RMS) of all the four seasonal RTMs were slightly smaller than the yearly RTM, and the accuracy of spring, summer, autumn and winter T m models is improved by 5, 13, 4, and 5% respectively. In addition, the bias and RMS of the differences between the GNSS-PWV resulting from the RTM-derived T m and the radiosonde-PWV were 1.13 and 3.21 mm respectively, which are reduced by 34 and 10% respectively. Thus the seasonal RTMs are recommended for GNSS meteorology for Hunan Province.

The Novel Copernicus Global Dataset of Atmospheric Total Water Vapour Content with Related Uncertainties from GNSS Observations

“…On the other hand, the use of near-surface air temperature as an approximation for T m may prove inadequate during certain seasons and in specific geographic regions (e.g., Arctic [63]), where regional linear regression models that differ but are similar could be applied [64,65]. In addition, the approach assumes well-established data flow from ground-based meteorological stations.…”

Constructing a precipitable water vapor map from regional GNSS network observations without collocated meteorological data for weather forecasting

“…While GNSS signals are transmitted from satellites to ground receivers, they are delayed by the terrestrial troposphere. In GNSS data processing, the tropospheric delay is usually expressed as the zenith total delay (ZTD) multiplied by a mapping function, and sometimes plus horizontal gradients for a better GNSS positioning performance (Lu et al, 2016). The accuracy of the GNSS ZTD estimates depends on the data processing strategies and on the global products used in the processing.…”

GPS signal derived precipitable water vapor and its applications in rainfall prediction

“…(2.15), some researchers were aware that the coefficients a and b in eq. (2.15 )are region and season specific, and thus proposed their own (T m -T s ) relationships [4,88,[95][96][97].…”

“…Similarly, there are empirical models for T m values [99] which are derived based on the temperature values estimated by the GPT and/or GPT2 model (which gives the surface temperature and pressure values based on the station location and day-of-year parameters). Yao et.…”