Update From Aquarius PI Gary Lagerloef: Data Calibration, Reprocessing, and Presenting Results
Greetings to all, and best wishes for a prosperous New Year. A couple of months have passed since my last update, and there is much to report on.
During the months of October and November, the project completed the Post Launch Assessment Review (PLAR) process with NASA, and December 1st, 2011, marked the beginning of the Aquarius Science Operations Phase. The Aquarius sensor and the SAC-D observatory continue to perform well. During the holidays, we reached a milestone of having received four-months of un-interrupted Aquarius data since the instrument commissioning sequence was finished on 25 August. Click here to see the 3-month average composite global image for the time period 28 August through 29 November 2011 using bias-drift corrected data (read more about this correction below). When compared to the initial 2.5-week average image we released in September, the 3-month average yields a much less noisy pattern which clearly shows the major climatological salinity features and smaller scale structures. (These images were prepared by Norman Kuring at NASA Goddard Space Flight Center).
The team has been busy presenting papers to the scientific community including the World Climate Research Programme Open Science Conference (24-28 October, Denver) and Fall American Geophysical Union (5-9 December, San Francisco) with some of the early results. Here are some upcoming meetings that include special sessions on salinity-related topics: Aquarius/SAC-D Science Team Meeting (11-13 April, Buenos Aires); Ocean Sciences Meeting (20-24 February, Salt Lake City); IEEE MicroRad (5-9 March, Rome); and 44th International Liege Colloquium on Ocean Dynamics (7-11 May, Belgium). I am finishing a Brief Report on Aquarius' progress for publication in Eos, Transactions, American Geophysical Union. I have also been working with the Journal of Geophysical Research-Oceans Chief Editor on plans for a special section on salinity remote sensing science results (i.e., NASA's Aquarius and European Space Agency's Soil Moisture and Ocean Salinity missions).
Although the Aquarius sensor is performing very well, the small calibration drift that I reported earlier has persisted. This has been the subject of much analysis and discussion among calibration working group members during the past several months. In October, we implemented an adaptive time-varying calibration correction for each radiometer channel using surface reference data fit to a seven-day moving window centered on each orbit file which is performing quite well. The calibration correction is done in a delayed mode and is now updated only through November. This is available as Version 1.2 on the data distribution site. We plan to release an update through the end of December in the next several days. As the overall system is better understood over time, newer and better algorithms will be developed. When new versions are ready, data will reprocessed from the beginning of collection (i.e., late August 2011). So stay tuned!
We continue to make good progress with Aquarius, and I will make an effort to provide these updates more frequently. We have a big year ahead of us in 2012.