The Adaptive Leading Edge Subwaveform (ALES) Retracker is a fitting algorithm used to improve the sea level estimations from satellite altimetry. While the biggest improvement involves the coastal ocean, the sea level data are reliable in the open ocean as well and improve the current standards in terms of noise content.
We currently provide sea surface height data at 1-Hz posting rate (one measurement every ~7km along a track) for single missions in their nominal phase. To derive the Sea Surface Height, we have removed the tides using the EOT tidal model, also described and available in this website.
We also provide the users with the tidal predictions, so that another tidal model can be applied, and with the Mean Sea Surface data from DTU15 model (Andersen and Knudsen, 2009), to allow the derivation of sea level anomalies.
The current version of SSH_ALES is not cross-calibrated. Thus, when combining different missions, mission offsets have to be applied in order to ensure aconsistent combination.
For more information on the way the sea surface height is derived and on which corrections are applied, the user can read the Chapter 4 of the COSTA user manual (http://epic.awi.de/43972/1/User_Manual_COSTA_v1_0.pdf).
If expert users want other corrections to be made available and/or a higher frequency of data (20-Hz posting rate instead of 1-Hz), please contact us through this website.
Work is in progress to improve the flagging of the data. In the present version, we suggest the users to exclude the following data:
Available version(s) of the product "ALES Sea Surface Height product (SSH_ALES)" in OpenADB.
|Jason-1||1 Hz||001 - 259||2002-01-15 06:29:21 - 2009-01-26 02:31:33|
|Jason-1 (Extended Mission)||1 Hz||262 - 374||2009-02-10 18:01:37 - 2012-03-03 12:59:11|
|Jason-1 (Geodetic Mission)||1 Hz||500 - 537||2012-05-07 16:04:18 - 2013-06-21 00:51:53|
|Jason-2||1 Hz||001 - 298||2008-07-12 01:25:09 - 2016-08-13 21:58:47|
The ALES data are distributed here in the hope that they will be useful, but DGFI-TUM provides these data "as is" without warranty, expressed or implied, as to the use or appropriateness of the ALES data, and there are no warranties of merchantability or fitness of these data for a particular purpose or use.
The product "Adaptive Leading Edge Subwaveform (ALES) Retracker" includes the following parameters.
|glon||Longitude of Satellite Footprint|
|glat||Latitude of Satellite Footprint|
|jday||Julian Day 2000|
|ssh||Sea Surface Heights|
|swh||Significant Wave Height|
|mssh||Mean Sea Surface|
|otide||Ocean Tide Correction|
|ltide||Ocean Load Tide Correction|
|distance||Distance to Coast|
|sflags||Geophysical Corrections Quality Flags|
|oflags||Orbit Status and Quality Flags|
|iflags||Instrument Status and Quality Flags|
A new manuscript is in preparation. In the meantime please cite: "The ALES SSH data were produced by DGFI-TUM and distributed via OpenADB (http://www.openadb.dgfi.tum.de). More details on the retracker and the product are available in Passaro et al. (2014), Passaro et al. (2015) and Passaro et al, (2017)."
Please also give credit to the respective institution(s) in charge of mission operation and maintenance (see bottom of this page).
Marcello Passaro acknowledges the value of the work performed with Paolo Cipollini (National Oceanography Centre, Southampton), co-author of the ALES algorithm in its first version.
All products are computed based on altimetry missions operated by NASA/CNES (TOPEX, Jason-1), ESA (ERS-1/2, Envisat, Cryosat-2), USNavy/NOAA (GFO), CNES/NASA/Eumetsat/NOAA (Jason-2, Jason-3), ISRO/CNES (Saral), and EUMETSAT (Sentinel-3). The original data sets are disseminated by AVISO, ESA, NOAA, and PODAAC.