3:45 PM - 4:00 PM
[SGD01-07] Development of a new software for GNSS-acoustic positioning (SeaGap)
Keywords:GNSS-Acoustic observation, Software, Seafloor geodetic observation
After the occurrence of the 2011 Tohoku-oki earthquake, importance of seafloor geodetic observations has been well known. GNSS-acoustic (GNSS-A) observations have reported various observational results: for examples, co- and post-seismic deformation due to the 2011 Tohoku-oki earthquake, and strain accumulation due to interplate coupling along the Nakai trough. Enhancement of the GNSS-A observational networks has been conducted abroad (e.g., Cascadia and Alaska subduction zones). Moreover, “open data” has been promoted in various fields recently; as for the GNSS-A community, Japan Coast Guard has started to open their observational data (e.g., Watanabe+, 2020, Zenodo). In spite of the enhancement of the GNSS-A observational networks and accumulation of GNSS-A observational data, only one GNSS-A positioning software is available at this moment, which is GARPOS (Watanabe+, 2020, Front. Earth Sci.). Then, users do not have the choice of analysis softwares like GNSS analysis software (e.g., RTKLIB and Bernese). This situation on the GNSS-A positioning software might disturb that various researchers entry to analyze GNSS-A observational data and develop the GNSS-A observation community as an academic field.
Here, I try to develop a new and user-friendly GNSS-A positioning software: SeaGap (Software of enhanced analyses for GNSS-acoustic positioning) which performs the positioning techniques developed by Tohoku University. These positioning technique adopts Nadir Total Delay (NTD) which is an analogy of Zenith Total Delay in GNSS positioning and expresses a temporal sound speed fluctuation; and they performs various types of positioning such as a kinematic GNSS-A array positioning and MCMC-based static array positioning that also estimates underwater sound speed gradients. However, these analysis programs were written in fortran to perform fast computation; thus, they are less readability and are difficult to be handled. Then, I adopt relatively new computational language “Julia” to construct SeaGap, which has high readability as well as python but has hight computational performance.
Data format of SeaGap is similar with that of GARPOS. Although it is impossible to directly apply the GARPOS dataset into SeaGap, we need not to conduct difficult data formatting. The unification of the data format for GNSS-A observational data has been under discussion so that SeaGap may need to be upgraded to support the unified data format in the future.
The current SeaGap has following functions based on the positioning methods developed by Tomita & Kido (2022): [1] Exact and approximate travel-time forward calculation, [2] Kinematic array positioning method for each acoustic ranging group (e.g., Kido+, 2006), [3] Static array positioning method considering NTD temporal fluctuation modeled by 3d B-spline functions, [4] Estimation of a GNSS antenna-transducer offset through [3], [5] Estimation of deep gradients through [3], [6] Individual transponder positioning considering NTD temporal fluctuation modeled by 3d B-spline functions, [7] Static array positioning method estimating shallow gradients and gradient depth by MCMC. SeaGap also equips various functions to visualize the positioning results and to conduct the other convenient GNSS-A processing.
Moreover, I prepare an online manual for SeaGap. The manual show explanation for the above functions and various tutorials so that other researchers can easily use SeaGap without the developer's guidance.
I develop the above new software and pre-open it on Github (https://github.com/f-tommy/SeaGap). I will improve the software even more user-friendly using feedbacks from test users.
Here, I try to develop a new and user-friendly GNSS-A positioning software: SeaGap (Software of enhanced analyses for GNSS-acoustic positioning) which performs the positioning techniques developed by Tohoku University. These positioning technique adopts Nadir Total Delay (NTD) which is an analogy of Zenith Total Delay in GNSS positioning and expresses a temporal sound speed fluctuation; and they performs various types of positioning such as a kinematic GNSS-A array positioning and MCMC-based static array positioning that also estimates underwater sound speed gradients. However, these analysis programs were written in fortran to perform fast computation; thus, they are less readability and are difficult to be handled. Then, I adopt relatively new computational language “Julia” to construct SeaGap, which has high readability as well as python but has hight computational performance.
Data format of SeaGap is similar with that of GARPOS. Although it is impossible to directly apply the GARPOS dataset into SeaGap, we need not to conduct difficult data formatting. The unification of the data format for GNSS-A observational data has been under discussion so that SeaGap may need to be upgraded to support the unified data format in the future.
The current SeaGap has following functions based on the positioning methods developed by Tomita & Kido (2022): [1] Exact and approximate travel-time forward calculation, [2] Kinematic array positioning method for each acoustic ranging group (e.g., Kido+, 2006), [3] Static array positioning method considering NTD temporal fluctuation modeled by 3d B-spline functions, [4] Estimation of a GNSS antenna-transducer offset through [3], [5] Estimation of deep gradients through [3], [6] Individual transponder positioning considering NTD temporal fluctuation modeled by 3d B-spline functions, [7] Static array positioning method estimating shallow gradients and gradient depth by MCMC. SeaGap also equips various functions to visualize the positioning results and to conduct the other convenient GNSS-A processing.
Moreover, I prepare an online manual for SeaGap. The manual show explanation for the above functions and various tutorials so that other researchers can easily use SeaGap without the developer's guidance.
I develop the above new software and pre-open it on Github (https://github.com/f-tommy/SeaGap). I will improve the software even more user-friendly using feedbacks from test users.