AVISO: Rss Feeds

Saral: data access open to all users for OGDRs and IGDRs products on June 20th, 2013

Tue, 18 Jun 2013 15:26:00 +0200

All participants have emphasized the extremely good results obtained with the SARAL mission and the very promising Ka band technology.
Considering the data quality, the project has decided to open the data access to all users for OGDRs and IGDRs products.
OGDRs and IGDRs product will be disseminated in version 'T' by June, 20th on CNES side on the AVISO ftp server.
A user release note is under finalization to provide detailed informations on the current data quality.

Spot-4: end of life and desorbitation planned for June 24th 2013

Mon, 17 Jun 2013 16:32:00 +0200

The Spot- 4 satellite was launched on March 1998 and it reaches now the end of its life. It was the first of its serie to integrate Diode system able to localize the satellite in real-time. SPOT-4, with on board a DORIS receiver of 1rst generation, will leave after more than 15 years of loyal services, far beyond the instrument and the spacecraft nominal life time.

Further information:

Space mission on Cnes website : Spot
International Doris Service (IDS)

update of processing chain planned on June 25

Thu, 13 Jun 2013 09:34:00 +0200

We are pleased to announce an update of the processing chain which calculates the model-based atmospheric corrections, associated with a vertical resolution increase of the ECMWF model. The number of model levels increases from the current 91 levels to 137 levels. The upgrade is planned to take place on June 25. The first operational run using the new resolution will be the 12 UTC June 25 assimilation and forecast run. For more information, please visit the ECMWF dedicated web page:http://www.ecmwf.int/products/changes/ifs_cycle_38r2/.

The increased number of levels enables a better representation of physical processes, clouds, inversions and vertically propagating gravity waves. For altimetric atmospheric corrections, we generally use the model data integrated from 3D to 2D to have model values at sea level.

Impact studies have been carried out on both vertical resolutions using Jason-2 products, by looking specifically at the following parameters: wet tropospheric correction, dry tropospheric correction, U and V model wind components, sea surface pressure and the Dynamic Atmospheric Correction. On average, the differences are rather small (a few hPa for pressure fields, 0.5 m/s for winds, a few mm for tropospheric correction). Only locally high discrepancies, mainly due to shifts in the location of highs, lows and fronts, can be expected.

The results on OGDR products indicate differences on the order of only tens of cm/s rms on model wind speed components, and less than 1 mm rms for the range corrections. The significant wave height is not significantly affected. On IGDR and GDR products, where the Dynamic Atmospheric Correction is applied, we have observed additionally range differences of 1-2cm rms over the ocean.

3-9 June 2013 week

Wed, 12 Jun 2013 16:47:00 +0200

La fonte des glaces deux fois moindre que prévue? (7 sur 7, 2013/06/06)
Climat: préserver les forêts aide à sauver les coraux (Sciences Avenir, 2013/06/05)
Tara Oceans Polar Circle : cap sur l'Arctique pour une récolte unique de plancton (Bulletins électroniques, 2013/06/03)
Climat dans le Grand Sud : ce à quoi il faut s'attendre (La Dépêche, 2013/05/28)
On line availability of articles depends on the Newspaper/magazine. We can't thus certify that above articles will be freely and permanently available.

June 2013: Is the ground rising or the sea decreasing?

Mon, 10 Jun 2013 16:31:00 +0200

Tide gauges are used to monitor sea level. However, they are anchored on lands, and thus monitor as...

Strong swell in French Polynesia on June 2013

Wed, 05 Jun 2013 17:01:00 +0200

Between 31th May and 3rd of June 2013, strong waves hit several polynesian archipels in South Pacific. Altimetry satellites (here an example with Saral, Jason-1 and Jason-2) have measured the significant waves height by multiple altimeter tracks over all the area, from south and up to -10°S (at Hiva Oa, in the Marquesas Islands, about -138°W, -10°S).


Map of significant wave heigths (in m) measured along-track by IGDR Saral (left) and Jason-1 (right) between May 30 and June 03, 2013 over South Pacific. Ground tracks in red, correspond to higher waves. Pass numbers plotted on each map are those plotted below. See a similar map for Jason-2.Credits Cnes/CLS. Plots made with the Basic Radar Altimetry Toolbox.

By selecting some individuals tracks and by plotting them vs latitude, it appears that Jason-1 (pass #237) and Saral (pass #284) measure a similar SWH. Both passes are separated only by few hours on 2nd of June. Jason-2 pass #017 crossed the area earlier (on 1st of June) by measuring higher significant wave heights (> 9m); around -33.5°S.

Significant Wave Height vs latitude for individual ground tracks: Saral in blue (pass #284, 2013/06/02); Jason-1 in red (pass #237 2013/06/02) and Jason-2 in green (pass #017, 2013/06/01). Plots made with the Basic Radar Altimetry Toolbox. Credits Cnes/CLS.

Sea state forecast models WFWAM from Meteo France, which assimilate altimetric data in real-time (here Jason-1 and 2), made a good prediction of this event; allowing to publish a wave warning bulletin.

Swell from Meteo France over Polynesia between 1st of June and 3rd of of June (one frame per 6 hours). Credits Meteo France, Courtesy of L.Aouf.

Further information:

Applications: Atmosphere, wind and waves
Sea Views: Maps of SWH for a given date/ given area. For this swell event, choose 2013/06/01 over the "South Pacific" area.

Saral also provides promising results over the Amazon river

Wed, 05 Jun 2013 08:38:00 +0200

The analysis of the Saral products over inland water is ongoing. Saral provides a new opportunity to monitor remotely the level of the major rivers, and comes at a perfect time to allow a continuous monitoring of rivers by carrying on the time series of data for inland waters initiated with ERS-2 in 1995, then continued with Envisat in 2002. These plots present the river level measured over an intersection of Saral ground tracks (pass number 063 and 478) with the Amazon (near the Amazon and Madeira confluence). The water levels are compared with the in situ measurement at Iracèma, available just 3 km upstream.

Water surface altitude (in meters) over the Amazon river (near the confluence of Amazon and Madeira rivers) along the Saral #063 and #478 ground tracks, between cycle 1 and cycle 3 (no data from pass #063 on cycle 1). Each curve represents the altitude in meters (Y-axis) along the ground track (X-axis represents the latitude) at a given cycle so each curve for a given pass is spacen from 35 days. Use the pass locator to visualize the ground tracks with Google Earth. CréditsCnes/Legos/IRD, S.Calmant.

Water levels time series derived from ERS-2 (triangles) between 1995-2002, Envisat (squares) between 2002-2010 and Saral (circles) from 2013. The blue and cyan colors used for the water level derived from altimetry correspond to passes #063 and #478. Both tracks are separated of 14 days for a given cycle. The red line superimposed are derived from in situ measurements at the Iracèma gauge, located 3 km upstream. Missing blue squares between 2010 and 2012 correspond to an orbit change for Envisat beyond November 2010. The missing red line between 2011 and 2013 correspondonds to a lack of in situ measurements. Credits Cnes/Legos/IRD, S.Calmant.

The agreement between in situ water level records and Saral data is already very good. In the coming months, we will further increase the Saral data quality over inland water by using dedicated processing methods

Further information:

Applications: Hydrology, Rivers
News, 2012-06-05: Record flood in the Amazon basin
News, 2009-05-14 Exceptional flood on the Amazon river
Image of the month:
- April 2010: Drought and floods in the Amazon basin
- - Mar. 2007: Malaria and altimetry in the Amazon
  - Oct. 2001: The Amazon under close surveillance
Altimetry applications in videaos: Hydrology
Data use case in Radar Altimetry Tutorial : Temporal water surface height variations in enclosed areas: the Amazon Basin

27 May - 2 June 2013 week

Tue, 04 Jun 2013 16:44:00 +0200

Éléphants de mer océanographes : 10 ans de succès (CNES, 2013/05/31)
'Le réchauffement climatique pour 2100 ne sera pas de 6°C, mais d'un peu plus de 2°C' (Express.be, 2013/05/31)
La fonte de la banquise est-elle responsable de ce printemps glacial? (Business Travel, 2013/05/30)
Continent de plastique dans l'océan : 5 fois plus de plastique que de plancton (Vedura, 2013/05/29)
Century-old science helps confirm global warming (IMAS, 2013/05/21) On line availability of articles depends on the Newspaper/magazine. We can't thus certify that above articles will be freely and permanently available.

Temporary interruption of LAS server

Fri, 31 May 2013 16:22:00 +0200

Due to a technical problem, the LAS is unavailable since today (2013/05/31). The problem is under investigation and we will keep you informed as soon as possible. We are sorry for this inconvenience.

Aviso Users Newsletter #9

Tue, 28 May 2013 16:31:00 +0200

We are pleased to announce you the publication of the ninth Aviso Users Newsletter focused on:

in-orbit and ongoing missions with the recent events on Saral/AltiKa,
the explanation and schedule for the change of the Ssalto/Duacs reference period
a Data Use Case with BRAT representing the combination of several satellites which greatly improves sampling,
news from the lastest and ongoing releases products, App and Online Extraction Service.

Further information:

Newstand: all Aviso Users Newsletters