Using Argo to validate remote sensing missions

With its more than 3500 automatic profilers, the Argo array is one of the most important component of the Global in-situ Ocean Observing System. The array provides measurements of temperature and salinity profiles down to 2000 m. These data are rapidly expanding the historical database of the ocean sub-surface (specially in the case of ocean salinity) and are providing novel information about the ocean’s vertical structure and its variability. Moreover, these data allow real-time monitoring, model-constraining and contribute to calibration and verification efforts.

Number of available profiles from January 2005 to December 2014: Shown are the total number of profiles, the delayed mode profiles as for Apri 27, 2015 and the number of delayed mode profiles with salinity.

Figure 1: Number of Argo profiles from January 2005 to December 2014: Shown are the total number of profiles, the delayed mode profiles as for April 27, and the number of delayed mode profiles with salinity.

The Euro-Argo ( research infrastructure, designed to coordinate the European contribution to Argo, is part of the European Strategy Forum on Research Infrastructures (ESFRI). Euro-Argo is expected to provide additional 50 floats per year and support about the 25% of
the Argo array.

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SMOS Sea Ice Concentration maps

Since more than a year ago, the Barcelona Expert Center (BEC) team researches on the capabilities of SMOS for the characterizations of the Cryosphere. 

First maps of the Arctic Sea Ice concentration from SMOS data have been produced for the year 2014, with the algorithm explained bellow.



Two indices have been chosen to compute ice concentration: Angular Difference (AD=TBV(θ_2)-TBV(θ_1)) and Polarization Difference (PD=TBV-TBH). The sensitivity of those indices to ice salinity and temperature is much less (about 60%) than that of raw TB’s, but they are still quite sensitive to the physical state (sea or ice). This property is very convenient for the empirical characterization of the physical state, because the distribution of the geophysical parameters is not very well known (specially for the ice salinity).

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BEC L4 soil moisture product is now “all-weather”

Soil moisture at fine-scale (BEC L4 soil moisture product) can now be estimated under all-weather conditions. A delayed 5-year (2010-2015) data set covering the Iberian Peninsula is already available, and maps from 2015 onwards are provided in near real-time. This is BIG news! The L4 product is obtained by combining SMOS brightness temperatures with higher spatial resolution MODIS information into fine-scale soil moisture estimates [1,2]. In all previous releases, the presence of clouds masked the information from MODIS and therefore the fine-scale soil moisture. In the new L4 version 3.0 or “all-weather” product, we are including additional information in the downscaling algorithm, which allows fine-scale soil moisture mapping from space independently of cloud cover.

With the L4 all-weather product, we plan to extend the downscaling approach to other climatic regions. See Fig. 1 for an example of its application over Europe on July 1, 2014 (ascending passes). The version 2.0 is also provided (Fig. 2) to illustrate the differences between the two versions.

BEC L4 soil moisture map at 1 km spatial resolution, from 1/07/2014 (AM).

Fig.1. Soil moisture map at 1 km spatial resolution (with version 3.0 downscaling), from 1/07/2014 (AM).

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5+ years of fine-scale soil moisture estimates available!!

At Barcelona Expert Center (BEC) we are able to provide a Level 4 (L4) Surface Soil Moisture (SSM) product with 1 km spatial resolution that meets the requirements of land hydrology applications. To do so, we use a downscaling method that combines highly-accurate, but low-resolution, SMOS radiometric information with high resolution, but low sensitivity, visible-to-infrared imagery to SSM across spatial scales. A sample L4 SSM map from September 1, 2014 (6 AM) is shown in Figure 1.

Fig. 1. SMOS-BEC L4 product from September 1, 2014 (6 AM).

This downscaling approach was first presented in [1] along with results of its application to a set of SMOS images acquired during the commissioning phase over the Oznet network, South-East Australia. Using reprocessed SMOS data obtained with the latest L1 and L2 processors, we have further developed and validated this technique; we now use SMOS polarimetric and multi-angular information in the downscaling method, which results in improved fine-scale soil moisture estimates [2].
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Barcelona World Race 2014-2015

The 2014-15 edition of the Barcelona World Race (BWR) has had an active ocean observation contribution that will provide new data about the ocean water dynamics and its environmental quality.

In addition to contribute to the build-up of the Argo system by deploying eight Argo profilers during January 2015, the One Planet, One Ocean & Pharmaton ship carried a Sea Bird SBE37-SI MicroCAT instrument to collect continuous (every minute) sea surface temperature and salinity measurements.

Photography by Mireia Perelló from

The One Planet, One Ocean & Pharmaton. Photography by Mireia Perelló from

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New study on the detection of cold-core rings in the Gulf Stream area using remote sensing platforms

The Gulf Stream plays a major role in the meridional transport of heat and salt across the North Atlantic Ocean. The Gulf Stream acts as a barrier between the cold (10-18 °C) and relatively fresh (salinity around 30-32 in the practical salinity scale) waters of the Labrador Current and the warm (23 °C), salty (36), clear, and unproductive waters of the Sargasso Sea. After leaving Cape Hatteras, the Gulf Stream forms large-amplitude meanders that may loop back onto themselves and break off the stream forming detached rings. Warm-core anti-cyclonic rings bring significant amounts of warm tropical water to the continental slope and shelf seas north of the Gulf Stream. Similarly, cold-core cyclonic rings bring cold, nutrient-rich shelf water, to the biologically barren Sargasso Sea waters. Detection of cold-core rings from satellite data has been quite elusive so far as the surface temperature signature rapidly disappears.

Figure 1

Sea Surface salinity on August 23, 2015 according to various SSS products with superimposed OSCAR velocities. The plot on (a) correspond to the one-degree binned Aquarius L3 map. The other three maps show the fusion of the map shown in (s) with: AVISO SSH (b); SMOS SSS (c); and AVHRR SST (d).

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SMOS in a Massive Open Online Course

The Barcelona World Race Ocean Campus has organised five courses on Instructure Canvas platform to provide the 2014-2015 round the world regatta followers with basic knowledge about the science of oceanography and other subjects like meteorology, telemedecine, chronobiology or nutrition. One of these MOOCs is “Oceanography: a key to a better understanding of our world” that includes a module on ocean remote sensing instructed by Jordi Font. This free course will start on April 20th and does not require previous knowledge in oceanography. Feel free to join us in this worldwide adventure!

NASA successfully launches its Soil Moisture Active Passive (SMAP) satellite

On January 31st, NASA successfully launched the SMAP satellite onboard a United Launch Alliance Delta II rocket. The satellite, designed to collect high resolution soil moisture maps on a global scale every two to three days, will improve the ability to forecast droughts, forest fires and floods, and will help in crop planning and rotation. On February 24th the reflector antenna was successfully deployed and in the following days the first radiometric data have been acquired.

Image: NASA, United Launch Alliance


In order to obtain detailed soil moisture measurements of the entire world, SMAP is placed in a near-polar sun-synchronous orbit, allowing the observatory to use Earth’s natural spin to maximize the area that can be scanned by the satellite’s instruments. The orbiter will use its L-band radar and L-band radiometer to scan the top 2 inches (5 cm) of our planet’s soil with a resolution of around 31 miles (50 km).

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Nodal sampling: removing tails and ripples from SMOS Brightness Temperatures

Since the beginning of SMOS mission, one of the problems that has strongly affected the quality of the retrieval of SSS from SMOS Brightness Temperatures (BT) is the presence of large human-generated Radio Frequency Interference (RFI) sources, as shown in the following figure:

Image acquired over a coastal area in Europe; several strong RFI sources and their trails are very noticeable

Image acquired over a coastal area in Europe; several strong RFI sources and the associated tails are very noticeable

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A review of microwave interferometric radiometry in remote sensing

Radio Science has recently published “Microwave interferometric radiometry in remote sensing: An invited historical review” by M. Martín-Neira, D. M. LeVine, Y. Kerr, N. Skou, M. Peichl, A. Camps, I. Corbella, M. Hallikainen, J. Font, J. Wu, S. Mecklenburg, and M. Drusch. The paper (Radio Science, volume 49, issue 6, pages 415–449, June 2014, DOI: 10.1002/2013RS005230) is led by Manuel Martín-Neira, the SMOS instrument (MIRAS) principal engineer, and is co-authored by three SMOS-BEC members: Adriano Camps, Ignasi Corbella and Jordi Font. We copy below the paper’s abstract:

The launch of the Soil Moisture and Ocean Salinity (SMOS) mission on 2 November 2009 marked a milestone in remote sensing for it was the first time a radiometer capable of acquiring wide field of view images at every single snapshot, a unique feature of the synthetic aperture technique, made it to space. The technology behind such an achievement was developed, thanks to the effort of a community of researchers and engineers in different groups around the world. It was only because of their joint work that SMOS finally became a reality. The fact that the European Space Agency, together with CNES (Centre National d’Etudes Spatiales) and CDTI (Centro para el Desarrollo Tecnológico e Industrial), managed to get the project through should be considered a merit and a reward for that entire community. This paper is an invited historical review that, within a very limited number of pages, tries to provide insight into some of the developments which, one way or another, are imprinted in the name of SMOS.

David and Goliath

This image of the first ESA ground tests of a MIRAS demonstrator was selected for the cover of the Radio Science issue. The online version of the paper can be seen at