Operational News

20.07.2010 [Jason-1] End of Life Plan

Jason-1 mission is starting today a series of maneuvers. Some impacts on products in terms of quality and latency are expected.[details]

25.06.2010 [Jason-1 & 2] Delivery delay on IGDR products due to Met anomaly

Due to an anomaly in meteorological fields, the JAson-1 and Jason-2 IGDR have some delays. [details]

10.06.2010 [Jason-1] situation improving

The situation of Jason-1 is largely improved starting with OSDR product named JA1_OSD_2PcS20100609_140024_07073[details]

04.06.2010 [Jason-1] Large off nadir angles on Jason-1 degrade the NRT product quality and coverage

Following the flip performed yesterday on Jason-1, the situation is again degraded with a very low STR1 performance (below 5% of tracking, being related with a bad beta angle configuration). This generates large off nadir on NRT products and even some altimeter lost of tracking and so associated impacts on off-line products.

A continuous monitoring of the performances is made, and we will report as soon as the situation changes.

12.04.2010 [Jason-1] Large off-nadir angles since March 2010

Since mid-March, a degradation of the on-orbit performance of the star trackers and gyro wheels on Jason-1 has caused large off-nadir angles of the platform.The most immediate impact has been on the Jason-1 Near-Real-Time OSDR products, because the altimeter retracking algorithm used for the OSDR products requires off-nadir angles less than 0.3 degrees. For example, since April 1 more than 15% of the SWH values reported on the OSDR products have been set to the default value.There is a lower impact on the Jason-1 I/GDR products because the MLE4 ground retracking algorithm used for these products allows off-nadir angles up to 0.7 degrees.However, during the past 3 days, off-nadir angles have been larger than 0.7 degrees, and in some cases has been large enough that altimeter has lost track. This loss of track has resulted with data gaps in the observation record. The Jason-1 project is investigating options to improve the situation. We apologize for the inconvenience.[details]

22.03.2010 [IGDR] Jason-1 reprocessed IGDR available

The Jason- 1 products (O/IGDRs) have been affected by the recent upgrade of the ECMWF model to higher resolution. Corrections have been implemented to solve the problem and all affected IGDR products have been reprocessed for the period 26 January to 17 February 2010 (from Cycle 297 - Passe 70 to Cycle  299  - pass 145).

Reprocessed IGDR are available on the Aviso website on through the (I)GDR page (http://www.aviso.oceanobs.com/en/data/products/sea-surface-height-products/global/gdr-and-igdr/index.html) or directly via FTP (ftp://avisoftp.cnes.fr/AVISO/pub/jason-1/igdr/).

Reprocessing of IGDR products Envisat are on-going. [details]

15.03.2010 Maintenance of Cnes information system building on March 17, 2010

There will be a maintenance of Cnes information system building on 2010 March 17 (max time: 03:00 - 14:30 UT)  with a network switch on backup lines planned from 2010 March 16 (15:00 UT) to March 17 (14:30 UT).

We try to minimize the possible disruption that could be caused, but you might notice some delay on products and data delivery during this period.

Ssalto team[details]

11.03.2010 [IGDR] Jason-2 reprocessed IGDR available

The Jason-2 products (O/IGDRs) have been affected by the recent upgrade of the ECMWF model to higher resolution (see previous news). Corrections have been implemented to solve the problem and all affected IGDR products have been reprocessed for the period 26 January to 17 February 2010 (from Cycle 57 - pass 197 to Cycle 60 - pass 18).

Reprocessed IGDR are available on this website on through the (I)GDR page or directly via FTP (ftp://avisoftp.cnes.fr/AVISO/pub/jason-2/igdr/).

Reprocessing of IGDR products for Jason-1 and Envisat is on-going.[details]

04.02.2010 Impacts on O-F/GDR and IGDR products due to changes in ECMWF model

Dear AVISO products users,

As you probably know, we use ECMWF atmospheric model pressure grids to derive dry troposphere and inverse barometer corrections for sea surface height measurements. Last week, on 26-Jan-2010, the ECMWF model was upgraded to a higher spatial resolution: www.ecmwf.int/publications/cms/get/ecmwfnews/251

We have since identified an impact on the O-F/GDR and IGDR products, due to interpolation of the new higher resolution surface pressure grid onto the lower resolution grid that is still being used operationally. This anomaly has impacts on Jason-1, Jason-2 and ENVISAT products.

The affected period for those missions are: 

For ENVISAT, FGDR and IGDR products have been affected by the ECMWF model resolution change from cycle 86 (pass 404) up to cycle 86 (pass 613).For Jason-1, OGDR and IGDR products have been affected by the ECMWF model resolution change from cycle 297 (pass 70) up to cycle298 (pass 3)For Jason-2, OGDR and IGDR products have been affected by the ECMWF model resolution change from cycle 57 (pass 197) up to cycle 58 (pass 130).

The largest impact is seen in the inverse barometer correction, which has static variations of up to 2 cm amplitude at a wavelength of ~ 50 km. This effect is most noticeable in regions within 200 km of the coast, but is not negligible outside those regions. The anomalous short-wavelength variations can be detected comparing IB values before and after the model evolution. The dry tropospheric correction is affected as well (~4 times smaller amplitude), but not the wet tropospheric correction.

The solution is to retain all the model's spectral information when interpolating from the high-resolution to low-resolution grids, which is an option when creating the operational grids. This change was implemented on 02-Feb-2010.

A smaller issue remains that the interpolation of the high-resolution ECMWF surface pressure grids to a lower resolution does not allow us to fully remove spectral leakage of land features onto the ocean. The remaining errors have a smaller amplitude (~20% of the short-wavelength features seen in the first figure), is also static in time, and almost exclusively affects regions within about 100 km of the coast. We are working on solving the remaining issue as well, and will keep you updated on our progress.

The affected IGDR files will be reprocessed for all missions. All issues related to the ECMWF model resolution change will be corrected prior to GDR production for this time period.

We would like to acknowledge our gratitude to Saleh Abdalla of ECMWF for his collaboration on this issue.

We thank you in advance for your understanding while we resolve these issues.

On behalf of the Jason-2 Measurement Systems Engineers[details]

25.01.2010 Increase in horizontal resolution of ECMWF model

Horizontal resolution of ECMWF model will be increased on the 26th January 2010. These meteo fields are used for altimetric corrections. Some impacts are expected.[details]