Exploring sea surface heights by using Airborne Laser Scanning

Resolution of satellite altimetry derived sea surface heights (SSH) is relatively low, whereas near coastal areas the data have poor accuracy. For monitoring SSH regionally, Airborne Laser Scanning (ALS) in conjunction with kinematic GPS-positioning can be a more accurate and high-resolution alternative. A case study was carried out at the southern shores of Gulf of Finland, the Baltic Sea. An ALS profile flown at an altitude of ~400 m was used for SSH determination. Two different algorithms for ALS trajectory calculations were compared and clear systematic discrepancies between the two were determined. Also, significant variations in backscattering of ALS pulses yield large data gaps even with near ideal flight conditions. The causes for this phenomena were analyzed and a possible explanation given. The accuracy of the sea level corrected SSH results was validated with a regional geoid and sea surface models. The ALS derived SSH values agree within 2 cm (in terms of standard deviation) with the geoid model.