N: 88 S: -88 E: 180 W: -180
Description
ATL07QL is the quick look version of ATL07 and is based on the same algorithms that generate the ATL07 final data products. Once final ATL07 files are available, the corresponding ATL07QL files are removed. ATL07 contains along-track sea surface height and sea ice height for segments of variable lengths for all beams as well as fixed 10-meter segments for strong beams. Heights are also computed using the DDA-Bifurcation algorithm for strong beams. The data were acquired by the Advanced Topographic Laser Altimeter System (ATLAS) instrument on board the ICESat-2 observatory.
Version Description
-Added starting along-track distance of sea-ice segment to main data group. Average along-track distance remains on product. The entire span of an ATL07 segment can be found using starting along-track distance and segment length.
-Introduced lognormal distributions to be used as alternate expected waveform table. If a sea ice height return does not provide a good fit to the standard expected waveform table using Gaussian distributions, re-process the height segment using lognormal expected waveform table. The original results are kept, and the results of the re-processed height segment are stored on new lognormal parameters.
-Implemented the option to process sea ice heights at half-stepping, 10-meter segment lengths. By default, the sea ice heights are constructed at variable-length segments, constructed by aggregating 150 photons. The segment length, and the amount of overlapping, can be modified with the control file (the constant-length segmenting may be run by adding the following override command to the control file: asas.atl07.buffered_segments_flag=1)
-Introduced DDA-Bifurcation algorithm. DDA provides a new surface finding algorithm which provides independently computed heights along with the ATL07 heights. The routine also allows for the bifurcation of the surface to detect and measure potential melt ponds. ATL07 sea ice segments within these potential melt ponds are flagged. These results should be considered experimental as sufficient testing has not been completed.
-Updated algorithm to apply Dynamic Atmosphere Correction (DAC) as a geophysical correction. Static and Dynamic inverted barometer corrections (computed within atlas_l3a_si) were used as geophysical corrections in v5 and v6. DAC is provided on ATL03 and does not need to be computed within atlas_l3a_si. This change introduces product consistency with surface height returns from the ATL12 ocean surface heights product.
-Introduced new fine-tracker algorithm to make it modular and introduce custom data groups to help with data handling and writing. Testing is ongoing with the updated algorithm, so the default algorithm is used by default. The new algorithm may be run by adding the following override command to the control file: asas.atl07.finetrack_flag = 1.
Product Summary
Citation
Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.