# Reference the seabed topographic depth observations based on the national mean dynamic topography model

## TL;DR

The study improves seabed depth observations in Vietnam by using a new national model instead of traditional tide gauge data.

## Contribution

A new methodology combining tide gauge data and the MDTVN22 model is proposed for more accurate seabed topography measurements.

## Key findings

- A 5 to 6 mm difference was observed between traditional and MDTVN22-based depth measurements.
- Validation in Hai Phong showed discrepancies of ±0.006 m between the two reference systems.
- The MDTVN22 model is recommended for better accuracy in seabed topography assessments.

## Abstract

The mean sea surface in different regions is non-equipotential, rendering Vietnam's traditional approach, which relies on the Hon-Dau tide gauge station as a reference, not yet scientifically invalid. To overcome this, our study utilized the Vietnam national mean dynamic topography model (MDTVN22) for depth observations, particularly in the Gulf of Tonkin. Covering 3430 monitoring sites in Hai Phong and 813 sites in Quang Ninh, our experiments highlighted a 5 to 6 mm difference between the mean sea surface and MDTVN22 references.

•Our research establishes a resilient methodology, integrating shore tide gauge station data and the MDTVN22 model, aimed at enhancing precision in depth observations.•Validation experiments in Hai Phong demonstrate a minimal discrepancy of ±0.006 m between measurements obtained from the traditional mean sea surface and the MDTVN22 model.•These findings underscore the significance of adopting the MDTVN22 model for improved accuracy in assessing Vietnam's seabed topography.

Our research establishes a resilient methodology, integrating shore tide gauge station data and the MDTVN22 model, aimed at enhancing precision in depth observations.

Validation experiments in Hai Phong demonstrate a minimal discrepancy of ±0.006 m between measurements obtained from the traditional mean sea surface and the MDTVN22 model.

These findings underscore the significance of adopting the MDTVN22 model for improved accuracy in assessing Vietnam's seabed topography.

Image, graphical abstract