Soon 8 candles for SMOS!! (2/8)

Category : Non classé, Satellite

After the first image it was obvious that SMOS was running smoothly but still more works had to be done. The Commissioning phase started. We were tasked to make the first products, validate them and select the final mode of operations. For instance two options were possible, dual or full polarisation. If full pol was attractive, it also meant a degradation of sensitivity. Luckily after many tests (SMOS was operated alternatively full and dual pol, one week each for enough time to be able to reach a decision) it was found that thanks to the instrument excellent performances ful pol was perfectly acceptable and was thus selected. But all was not nice. Over oceans reaching the hundredth of a K was challenging , stability was yet to … stabilize etc. For the former  J. Tenerelli suggested to use a diagnostic tool the so called OTT (Ocean Target Transformation) which was soon to become « the tool » over ocean surfaces. for the latter the instrument did stabilize in May. This is why we generally recommend to only use data from June 2010 for delicate studies. But all this was expected and did not come as a surprise. the surprises were really bad news…

First the local oscillators of one arm, once disturbed, did seem unable to relock and needed a complete reboot… not good. This was swiftly cured by using switch to the redundant (nominal actually) segment. Again business as usual. What was not was teh discovery of RFI (radio frequency interferences) in our protected band!!

We expected some perturbations and our algorithms all had a RFI detection scheme … what we did not expect is such a large quantities of sources !

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Situation (RFI probability) in December 2009 – July 2010 (P Richaume)

This obviously needed some sort of an action! we started identifying, locating, reporting these bad guys. Some were out of band emissions, but too strong to be legal, some downright « outlaws ». emitting in band. The work was/is done by Colleagues at ESAC and at CESBIO while the  reporting is done through the ANFR and managed / coordinated by ESA with some success as in many areas the situation is significantly improved (North America, Greenland, western Europe, …). the « cleanest country is probably Australia while the darkest is Japan which changed in 2011 from rather OK to completely obscured by RFI. Japan is no more on the L band Map!

These findings enabled Aquarius to be prepared while SMAP could design a very sophisticated receiver able to reduce the impact of RFI on data.

But we have to be very careful many frequency greedy groups are also lurking in the background on top of those mentioned above… which could jeopardize the wealth of results L band radiometry ids offering us (more about this in the next posts) and which can be illustrated by the first ever Soil moisture – Ocean Salinity map ever produced from space .. thanks to SMOS

Image1Soil Moisture and Ocean salinity over the globe (August 2010) (F Cabot).

Note that since 2010 many progresses were made and we have much improved results by now… stay tuned!

Soon 8 candles for SMOS!! (1/8)

Category : Non classé

As a consequence, and following an idea suggested by Nemesio, we will endeavour to post every day for the next 8 days a small story on SMOS…

Today let us reminisce a little…

smos ready for launchSMOS & Proba 2 Launch campaign with Rockot launcher

SMOS (and Proba) under the shroud and then on the Launch pad

At the end of October 2009, the  satellite (SMOS on a PROTEUS platform), with its friend Proba, was packaged on a Rockot launcher and launched smoothly, accurately and efficiently on its orbit on November 2 2009. All the deployment (solar panels, arms loaded with antennas) went also a clockwork to enable the reception and processing of the first image ever taken from space at L band with an interferometer on November 17th.

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Crucial moment: Arms are being deployed

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The First Soil moisture Map

Yes! this is indeed the first ever soil moisture image made from a space borne interferometer. Obviously it is not perfect but it simply showed that it worked!! the next challenge was to retrieve Sea surface Salinity… and improve the soil moisture retrievals  stay tuned

Solar Flares as seen by SMOS

Category : Non classé

Dear SMOSers

Raúl Díez-García from the SMOS Calibration Expertise Centre at ESAC (Spain) tells us that last Wednesday (September 6th 2017) SMOS was able to observe the monster X9-class solar flare. Se below the Sun’s brightness temperatures of this event. At the maximum, it almost reaches 21 million Kelvin which is kind of hot!. He provided the following charts:

SolarFlare_X9_20170906SMOS observed temporal evolution of the Suns brightness temperatures during a solar flare (2017 09 06)

Find more details about the event here. I found it quite impressive!

But this event was followed by another one as the same sunspot erupted again last Sunday (September 10th 2017). It also was quite strong, being X8 class. See below the observed BT, more than 4 million Kelvin.

SolarFlare_X8_20170910SMOS observed temporal evolution of the Suns brightness temperatures during a solar flare (2017 09 10)

So if you are operating an L band radiometer double check your measurements for this period!



SMOS and Harvey

Category : Non classé

As most of you are well aware the Hurricane Harvey Texas very recently showing that maybe climate change is not a joke.

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<– Harvey (Image: NASA)

Harvey’s  forecasted trajectory (National Hurricane Center, National Oceanic And Atmospheric Administration) ^

SMOS monitored wind speed while Harvey was travelling in the Gulf of Mexico and then we have been able to monitor the flooding using SMOS NRT SM data  (Nemesio Rodriguez-Fernandez – CESBIO) as depicted in this animation from August 20 to August 31st (click to see animation)

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