Further by downloading this data the user acknowledges that they agree with the NERC data policy (), and the following conditions:

1. To cite the data in any publication as follows:

DATA REFERENCE

Jordan, T., & Robinson, C. (2022). Rectified airborne Lidar data over Thwaites Glacier catchment between 1st January and 30th December 2019 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/6909792B-FADF-4DE6-AC2A-D32FA76A8339

2. The user recognizes the limitations of data. Use of the data is at the users' own risk, and there is no warranty as to the quality or accuracy of any data, or the fitness of the data for your intended use. The data are not necessarily fully quality assured and cannot be expected to be free from measurement uncertainty, systematic biases, or errors of interpretation or analysis, and may include inaccuracies in error margins quoted with the data.

Methodology:

Lidar data was collected using a Riegl Q240i-80 scanning system mounted in the camera bay of the BAS geophysically equipped twin otter. Coincident attitude data was collected using an iMAR inertial navigation system (INS) (from Lamont Doherty Earth Observatory for the Jan 2019 season, and from BAS for the December 2019 season). Data processing was carried out by a sub-contractor (Terratec - https://terratec.no/en/). For each season (January and December) a boresight calibration was carried out using the Terrasolid software modules Terramatch and Terrascan. This calibration utilised a specific calibration data-set collected over the BAS Rothera Research Station. After calculation of the boresight values the remaining data for each season were processed using Riprocess with the appropriate boresight values. During the main survey data was collected on as many flights as possible, but due to operational constraints Lidar data is not available on all flights. As Lidar was not a priority, swaths do not typically overlap, so further calibration in the main survey area was not possible. The generally feature poor ice surface would also hamper such calibration. In addition it must be noted that removal of spikes due to clouds or other atmospheric returns has not been carried out. However, most flights were flown in clear weather.

The list of variables is as follows:

* longitude x - in degrees from the WGS84 datum

* latitude y - in degrees from the WGS84 datum

* altitude z - in meters

* intensity - arbitrary value between -128/128

* scan_angle - in degrees

* GPS_time

* datetime_utc - converted GPS time to UTC taking into account leap seconds in YYYY-MM-DD HH:MM:SS

Data quality:

Analysis of repeat passes over the Runway suggests the corrected data has an internal accuracy of ~10 cm.

Note no de-spiking, or removal of cloud features has been undertaken.