Training at IISc, Bangalore on the use of Microwave RS for Agro-hydrology

Category : Non classé

Are you in Bangalore next week ? and interested on learning about the use of microwave data (radiometers, SARs and Altimeters) then contact Prof. Muddu Sekhar to join us on this training.
annoucement_micro_training

and the associated program:

prog_micro_training

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

Category : Non classé

Happy Birthday SMOS !

(As you have guessed the eight « ! » correspond to 8 candles .. upside down as SMOS is looking downward).

Yes SMOS has been in space for eight years now and, for a satellite, this is starting to be a somewhat venerable. So….What is next?

But first a quick appraisal:

We have tried to depict in the previous blogs some of the achievements only giving a very small part of what was done in science (According to Web of Science, 1065 papers since 1999 and an H index of 52. Are there many missions which can claim such a scientific footprint (I have done it for other missions but by sheer charity I won’t mention it here) and applications (several operational applications after only a few years (remember that SMOS in an explorer and makes measurements never done before to be compared to mission with a very long track record but very few operational applications)?

Now about the next steps…

After SMOS came Aquarius and SMAP. Each with a different instrumental concept but a common feature, L band radiometry.  When accounting for system differences (spatial resolution, view angle or revisit) one can say that  the missions provides excessively similar results (as shown for instance by Chen and Bindlish when the run the SMAP algorithm on SMOS data and merged the two). All have clearly demonstrated the potentialities, innovation and unicity of such measurements. There are simply no equivalent in any other domain! One mustn’t be fooled by proxies claiming to be measurements.

Back to our topic though. Where do we stand ?

Aquarius is no more (due to a platform issue incidentally) and SMOS or SMAP won’t last forever (a sad thought indeed). Considering the time it takes to make and launch a satellite, one may wonder why there are no current plans in Europe (or US) for a follow on.This is not due to a lack of information as we have shown (at EU workshops for instance) what consequences a data gap could bring and how unique were the measurements. We even sent EU 3 letters (Land, Ocean and Cryosphere) signed by several hundred scientist worldwide, and I was flabbergasted when I saw the answers we received: a kind of « not interested » form letter. Especially when one can see that Copernicus programme « application oriented » does not wish to consider L band continuation, but nurtures plans with exploratory missions or copies of planned missions. One may also wonder as we were also told that Copernicus does not consider earth explorer as potential candidates (irrelevant) while having one in their plans.

To make a long story short, agencies funded to develop explorers cannot support the follow ones (though they do it when it pleases them) and operational agencies prefer to support explorers than new operationally validated missions. Funny isn’t it?

All his dos not really make sense while our decision makers are, without any doubt, sensible people. So why are we in such a catch 22 scenario?

My belief is that the afore mentioned decision makers are no gurus in remote sensing and have to rely on counsellors who in many cases are no gurus either but keen to promote industries and other lobbies (so L band is obviously lacking an industrial backer!). Add to this mix a couple of hoity-toity advisers and pseudo specialists you get the big picture!

I am also a bit surprised to see that some operational agencies gave very stringent requirement before even considering assimilating SMOS. All the requirements were satisfied but to no significant result up to now except regular postponements to go operational while they are ready to assiimilate other datasets satisfying none of the requirements dictated for Smos (and proving to be quite neutral incidentally. As if they feared to have to update improve their model now that real measurements are coming in, killing their adjusting functions. I also heard people saying assimilating SMOS did not have much impact but forgetting to mention that their models are not designed to assimilate SSS….

But despite all this we haven’t lain on our oars and worked hard to prepare follow ons. Several options are open

The fastest would be to take existing concepts and update /improve from gained experience while the most efficient would be to review concept to achieve even more ambitious goals. We are also working on a improved SMOS concept with a typical native resolution of 10 km why other look at the potential L+P band concept. Adding active component is also an option to be considered. Finally we are also working on futuristic concepts !

End of November we will have a meeting at CESBIO to develop our strategywith respect to future L band missions and a meeting at ECMWF for the way forward in terms of applications.

A small note here about resolution by the way. Native means to me 3 db Beamwidth. Obviously there are techniques to dis aggregate and achieve higher resolution. I also refer to the  » dB footprint not the grid sampling. It is always amazing to me to see people (assumed to be competent and honest) comparing two different  instrument spatial resolutions by comparing the native of one with the sampling of the other. may be they simply do not know how to read the specs or limit their analysis to coffer table brochures (or are not honest / competent which never happens of course).

Also note that if no L band mission flies in the near future, the likelihood of loosing our very valuable protected bandwidth will become significant.

Well SMOS is 8 years old now (in space! but was initiated long before that) and we can only wish it many happy returns!

I believe we cannot end this little look back without thanking those who had the vision and supported our proposal at CNES and then ESAin teh mid ’90s, as well as mentioning and thanking enormously the team – led by Achim Hahne – who made our dreams come true and produced with CNES this wonderful mission, still running like clockwork (with all indicators bright green) after 8 years. We also have to thank the teams at ESA and CNES, in Toulouse, Frascati and Villafranca who – led by Susanne Mecklenburg – deliver all the excellent quality data in a very timely fashion (with two Near Real time products!) since launch. These two OP teams at CNES and ESAC do a terrific work!

And of course thanks to all the l band radiometry users and the ESLs who produced all this science and these applications!

I wish to end this set of post with an apology to all those I did not mention while they deserve to be. I made the posts on the spur of the moment with the illustrations I had at hand to realise soon after posting them that I could have added easily some other very relevant example. Sorry! I hope it will be an incentive  for those frustrated to put a post on this blog!

Long life to SMOS and thanks to all those who made and make it possible!

Yann

Soon 8 candles for SMOS!! (4/8)

Category : CATDS, Cal/Val, Data, L2, Non classé, ground measurements

Today let’s have a look back on what was done over land… but remember: it is only a quick summary of part of the findings!!

blogyhk1

Of course all the emphasis at the beginning was on the soil moisture retrievals over what as called « nominal surfaces », which meant land surface with moderate vegetation cover (fallow, crop land, savannah etc..) with all the cal val efforts related to it. For this in particular, several sites were dedicated to Cal Val (VAS in Spain, UDB in Germany, AACES/COSMOS/NAFE in Australia, and later HOBE in Denmark, with also sites in France, Poland, Finland, Tibet, etc…). We also relied heavily on the USDA so called « Watershed sites » and various sparse networks. Actually it is for SMOS that ESA and NASA decided to start the International Soil moisture Network.

lewis-faugaAACES 6MELBEX-II EMIRAD Installation 004LEWIS_3IMG_9674ELBARA-Sodankyla

Various pictures SMOSREX, AACES, VAS, Crolles, Mysore, Sodankylä …

Surprisingly enough we obtained good results almost immediately. But this was only the beginning as, in parallel, both level 1 and level 2 made significant progresses, leading to always improved retrievals. Actually with such fast progresses, it has always been a bit of a frustration to see people use not up to date products, as publications looking at SMOS data tended – for obvious reasons – to be a couple of version old (but generally failed to stipulate which version they were looking at!).

The most striking features of these always improved retrievals was, to me, the fact that the range of validity tended to regularly increase. Low to medium topography did not seem to a be a limitation, we managed to make sense in case of flooded areas (see for instance Mississipi floods) and we could get information in case of dense vegetation. The Tor Vergata University for instance related very quickly the vegetation depth to tree height and performed soil moisture retrievals under rainforest. No so accurate of course, but the tendencies are well depicted.

blogyhk2

SMOS opacity vs tree height from ICESat for two season (Rahmoune et al)

The only trouble we had was that the vegetation optical depth was not as satisfactory as we would have expected. It remained noisy in spite of significant overall progresses. To address this problem and also to keep on improving our retrievals (parametrisations) INRA and CESBIO worked on a different approach, the so called SMOS-IC and, lo and behold, first results are rather amazing! We believe we have again struck gold. More about this in the near future!

To finish with the surface soil moisture and vegetation opacity retrievals, we were faced with the fact that the retrieval algorithm is not so fast and thus tests or re-processings are a lengthy and tedious. This was another motivation for SMOS-IC but we also wanted to go a step further and, as soon as enough data was acquired, we developed a global neural network retrieval scheme. It has since been implemented in ECMWF and delivers Soil moisture fields less than 3 hours of sensing, paving the way to many applications…. to be summarised soon: stay tuned!

Further reading

Fernandez-Moran, R.; Al-Yaari, A.; Mialon, A.; Mahmoodi, A.; Al Bitar, A.; De Lannoy, G.; Rodriguez-Fernandez, N.; Lopez-Baeza, E.; Kerr, Y.; Wigneron, J.-P. SMOS-IC: An Alternative SMOS Soil Moisture and Vegetation Optical Depth Product. Remote Sens. 2017, 9, 457.

Kerr, Y. H., et al. (2012), The SMOS Soil Moisture Retrieval Algorithm, IEEE Transactions on Geoscience and Remote Sensing, 50(5), 1384-1403, doi:10.1109/tgrs.2012.2184548.

Rahmoune, R., Ferrazzoli, P., Singh, Y., Kerr, Y., Richaume, P., Al Bitar,  A. SMOS Retrieval Results Over Forests: Comparisons With Independent Measurements. J-STARS ,2014

Rodriguez-Fernandez, N.J., Aires, F., Richaume, P., Kerr, Y.H., Prigent, C., Kolassa, J., Cabot, F., Jimenez, C., Mahmoodi, A., & Drusch, M. (2015). Soil Moisture Retrieval Using Neural Networks: Application to SMOS. Ieee Transactions on Geoscience and Remote Sensing, 53, 5991-6007

Vittucci, C., Ferrazzoli, P., Kerr, Y., Richaume, P., Guerriero, L., Rahmoune, R., & Laurin, G.V. (2016). SMOS retrieval over forests: Exploitation of optical depth and tests of soil moisture estimates. Remote Sensing of Environment, 180, 115-127

Soon 8 candles for SMOS!! (3/8)

Category : Non classé

Jacqueline Boutin, with Audrey Hasson, sent me this contribution, as part of our series of blog stories, to illustrate each day using a new case example, how it reveals, with unprecedented details, the influence of large scale climate events, like ENSO, Indian Ocean Dipole … on the two key hydrological cycle variables. Actually,the 2010-2017 SMOS measurements time series has allowed an unprecedented and unique monitoring of Sea Surface Salinity (SSS) and Soil Moisture (SM) and Cryosphere using L-band radiometry. here is one example!

The signature of ENSO on equatorial and extra-equatorial SSS in the Pacific Ocean

A. Hasson, J. Boutin and S. Marchand (LOCEAN, Paris)

Nearly 8 years of Sea Surface Salinity retrieved from the SMOS mission has enabled the observation of inter-annual variations associated with the El Niño Southern Oscillation. SMOS was launched just in time for a great two-year long La Niña event from mid 2010 to early 2012. Followed in 2014 a small El Niño event that prepared the Pacific Ocean for a large event from mid 2015 to mid 2016.

1- The equatorial SSS variability:

In the Western Pacific Ocean, a large body of fresh waters called the fresh-pool swings along the equator together with the El Niño Southern Oscillation as observed from in situ observations. SMOS measurements enables the much more precise description of the fresh-pool displacement and its previously unknown extension. In 2011, the equatorial western Pacific fresh pool retracts all the way to the western edge of the Pacific Ocean whereas in 2015 the fresh waters extend well east of the dateline.

JB-blog1-1

Caption: 2010-2017 longitude-time plot of SMOS SSS averaged between 2ºS and 2ºN. The NINO3.4 index is displayed on top, centered on the dateline, blue during La Niña and red during El Niño https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Data/nino34.long.anom.data. (SMOS CATDS CPDC L3Q products)

To know more about associated work:

A. Hasson, M. Puy, J. Boutin and E. Guilyardi; Northward Propagation across the Tropical North Pacific Ocean Revealed by Surface Salinity: How El Niño Anomalies Reach Hawaii?, submitted to JGR-Oceans

Boutin, J., J.L. Vergely, S. Marchand, F. D’Amico, A. Hasson, N. Kolodziejczyk, N. Reul, G. Reverdin (2017), Revised mitigation of systematic errors in SMOS sea surface salinity: a Bayesian approach, Remote Sensing of Environment, in revision.


2- The eastern Pacific fresh-pool:

Heavy rain from the Inter-tropical Pacific Convergence Zone is associated with a large area of low surface salinity in the eastern Pacific Ocean. In this very under sampled region of the ocean, SMOS gives us great insight in the ocean variability.

Since launch, an extension of the eastern Pacific freshwaters is observed as shown around 18ºN. Fresh waters are trapped east of 110ºW during the 2011 La Niña and extend to the dateline following the 2015 El Niño.

JB-blog1-2

Caption: 2010-2017 longitude-time plot of SMOS SSS averaged between 16º and 20ºN. The NINO3.4 index is displayed on top, centred on the dateline, blue during La Niña and red during El Niño https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Data/nino34.long.anom.data. (SMOS CATDS CPDC L3Q products)

To know more about associated work:

A. Hasson, M. Puy, J. Boutin and E. Guilyardi; Northward Propagation across the Tropical North Pacific Ocean Revealed by Surface Salinity: How El Niño Anomalies Reach Hawaii?, submitted to JGR-Oceans

Boutin, J., J.L. Vergely, S. Marchand, F. D’Amico, A. Hasson, N. Kolodziejczyk, N. Reul, G. Reverdin (2017), Revised mitigation of systematic errors in SMOS sea surface salinity: a Bayesian approach, Remote Sensing of Environment, in revision.

Guimbard S., N. Reul, B. Chapron, M. Umbert and C. Maes, 2017. Seasonal and interannual variability of the eastern tropical Pacific fresh pool, J. Geophys. Res. Oceans, doi: 10.1002/2016JC012130.

Alory, G., C. Maes, T. Delcroix, N. Reul, and S. Illig, 2012. Seasonal dynamics of sea surface salinity off Panama: the far eastern Pacific fresh pool. J. Geophys. Res., 117, C04028, doi:10.1029/2011JC007802.

3- The extra-equatorial anomalies

The unprecedented spatial and temporal coverage of the SMOS mission reveals poleward pathways of equatorial SSS anomalies as shown for the 2011 La Niña (Hasson et al. 2014) and for the 2014-2015 El Niño events (Hasson et al. 2017 submitted). Anomalies created at the equator by the displacement of the western Pacific fresh-pool and off the equator are exported poleward by the Ekman drift in a complex system of tropical currents.

JB-blog1-3

Caption: 2010-2017 latitude-time plot of SMOS SSS anomalies produced by the CEC-LOCEAN averaged between 150º and 170ºW. The NINO3.4 index is displayed on top, centered on the equator, blue during La Niña and red during El Niño https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Data/nino34.long.anom.data. (SMOS CATDS CPDC L3Q products)

To know more about associated work:

A. Hasson, M. Puy, J. Boutin and E. Guilyardi; Northward Propagation across the Tropical North Pacific Ocean Revealed by Surface Salinity: How El Niño Anomalies Reach Hawaii?, submitted to JGR-Oceans

A. Hasson, T. Delcroix, J. Boutin, R. Dussin, and J. Ballabrera-Poy (2014); Analyzing the 2010–2011 La Niña signature in the tropical Pacific sea surface salinity using in situ data, SMOS observations, and a numerical simulation, Journal of Geophysical Research: Oceans, 119(6), 3855-3867, doi:10.1002/2013JC009388.

Boutin, J., J.L. Vergely, S. Marchand, F. D’Amico, A. Hasson, N. Kolodziejczyk, N. Reul, G. Reverdin (2017), Revised mitigation of systematic errors in SMOS sea surface salinity: a Bayesian approach, Remote Sensing of Environment, in revision.

download wordpress themes