Defining the vertical datum based on an equipotential surface : a case study of Metro Manila | |
| Author | Bandojo-Reyes, Rosalie |
| Call Number | AIT Diss. no.RS-14-04 |
| Subject(s) | Leveling Geodesy--Philippines--Manila Geographic information systems--Philippines--Manila |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Remote Sensing and Geographic Information System |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. RS-14-04 |
| Abstract | The Philippines is a country composed of many islan ds hence problem of many reference levels based on different tide gauges all over the country results in not homogeneous heights. This is because the MSL observ ed from these many tide gauges are not of the same level due to oceanographic effects (e.g. salinity, temperature and pressure). The MSL is not a stable surface because it changes with time. Satellite geodesy is now playing a very important role in the determination of the true shape of the earth that is based on gravity measurements. The International Associat ion of Geodesy is advocating a World Height System based on an equipotential surface tha t is unlike MSL is time-invariant. The development of a LGM, which is an equipotential sur face that approximates the MSL, is the main objective of this study. The area selected for this study is Metro Manila a nd vicinities. The region was selected based on the availability of the data requ ired in the development of a LGM and for validation. The newly acquired geodetic leveling me asurements provided additional inputs for height data analysis to determine the stability of the PTGBM. The validation of recently released GGMs is a determining factor whether a loc al geoid model is still warranted. The validation results of the combined type GGMs (model s developed using a combination of satellite and terrestrial gravity data) namely: EGM 2008 and EIGEN-6C2 showed RMSs of 13.8 cm and 12.5 cm respectively. The challenge of this study is to develop a geoid model that could surpass the accuracies of the two combin ed type GGMs. The LSMSA or KTH approach was used for the development of a local ge oid model because it takes advantage of the improved accuracy of the GGM in the long to med ium wavelengths of the earth’s gravity field. This is possible due to the minimization of the truncation error and error in terrestrial gravity and GGM. The results of the analyses of geodetic and GPS lev eling revealed that the PTGBM is stable and therefore no quantity related to vertica l deformation was subtracted from the MSL heights. However, other areas in Metro Manila are a ffected by vertical deformation as only 16 out of the 61 BMs analyzed exhibited stability. The validation was carried out by comparing the geoid heights from GGMs and LGM with the geoid height derived from GPS and geodetic leveling. The validation of GGMs and LGM also showed that the 1970 LVD, the LVD before the observed sea level rise in Manil a Bay produced the least RMS compared with the recent 2008 LVD. The final LGM has achiev ed an accuracy of 11 cm using a 3º integration cap surpassing the accuracy of EGM 2008 and EIGEN-6C2 and the previous LGMs developed. With the computed post-processed st andard deviation of GPS survey at 2.78 cm and error from geodetic leveling at 2.8 cm considered, the accuracy of the LGM can be around 5 cm. |
| Year | 2014 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. RS-14-04 |
| Type | Dissertation |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Remote Sensing (RS) |
| Chairperson(s) | Nagai, Masahiko |
| Examination Committee(s) | Taravudh Tipdecho ;Sarawut Ninsawat ;Kamiya, Yoshikazu |
| Scholarship Donor(s) | Philippine Council for Advanc e Science and Technology Research and Development, Philippines ;Asian Institute of Technology Fellowship |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2014 |