Vertical land motion monitored with satellite radar altimetry and tide gauge along the Texas coastline, USA, between 1993 and 2020

It is crucial nowadays to accurately monitor vertical land motion (VLM) near coasts and understand its spatial and temporal variability to quantify its impact to water-land interactions. This study developed and employed a double difference (DD) network adjustment method to reconstruct daily VLM time series and estimate their trends using sea-level observations recorded at 24 tide gauge (TG) stations located on the Texas coastline between 1993 and 2020. Based on the first difference between TG and the satellite radar altimetry (SRA) observations, the method calculated DD between correlated TG pairs to mitigate sea-level variations. Then all potential connections of TG pairs across the 24 stations were combined to form a TG network regarding the DD values. On a daily basis, the DD values reflected relative elevation difference for a specific connection and the network could be solved via weighted least squares to reconstruct elevations (i.e., VLM time series) at different TG stations. Results indicated that at most TG stations, clear VLM patterns were restored and found to be largely consistent with time series derived from continuously-operating global navigation satellite system (cGNSS). In addition, greater than 80% of the TG stations used in the work showed a linear VLM trend with an uncertainty of less than or equal to 1.0 mm/yr. The proposed DD network adjustment method provides long and continuous VLM time-series results, and has a potential to complement other geodetic techniques, particularly along the coastal areas where TG stations were densely installed.