# ZPD Retrieval Performances of the First Operational Ship-Based Network of GNSS Receivers over the North-West Mediterranean Sea

## TL;DR

This paper describes a ship-based GNSS system for measuring atmospheric conditions at sea and shows it can accurately estimate ZPD values over the Mediterranean.

## Contribution

The paper introduces an operational ship-based GNSS network for ZPD estimation and validates its performance over three years.

## Key findings

- The system achieved ZPD correlation values between 0.94 and 0.65 compared to MERRA-2 data.
- Root mean square errors ranged from 18.4 to 42.9 mm across installations.
- The system demonstrates viability for operational meteorological applications over sea areas.

## Abstract

This work presents the design and implementation of an operational infrastructure for the monitoring of atmospheric parameters at sea through GNSS meteorology sensors installed on liners operating in the north-west Mediterranean Sea. A measurement system, capable of operationally and continuously providing the values of surface parameters, is implemented together with software procedures based on a float-PPP approach for estimating zenith path delay (ZPD) values. The values continuously registered over a three year period (2020–2022) from this infrastructure are compared with the data from a numerical meteorological reanalysis model (MERRA-2). The results clearly prove the ability of the system to estimate the ZPD from ship-based GNSS-meteo equipment, with the accuracy evaluated in terms of correlation and root mean square error reaching values between 0.94 and 0.65 and between 18.4 and 42.9 mm, these extreme values being from the best and worst performing installations, respectively. This offers a new perspective on the operational exploitation of GNSS signals over sea areas in climate and operational meteorological applications.