2016 Microwave Radiometry and Remote Sensing of the Environment

April 11-14, 2016
Espoo, Finland

The 14th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad 2016) took place April 11-14, 2016, on Aalto University Campus, Espoo, Finland. The meeting covered wide radiometry applications and fields such as soil moisture and state, ocean salinity, cryosphere, ocean dynamics, sounding, radiometer calibration, radio frequency interference issues, and new technologies. MicroRad 2016 is sponsored by the Geoscience and Remote Sensing Society (GRSS) of the Institute of Electrical and Electronics Engineers (IEEE) and Aalto University.
Documents (8)
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Active/Passive Remote Sensing of Vegetation: Theoretical and Experimental Results
Guerrinero, L, Ferrazzoli, P., Vittucci, C., Aurizzi, M., and Vergata, T. (11-Apr-16). In the last decades, researches based on passive and active systems were mostly conducted separately. More recently, a joint use of the two techniques were investigated with the objective of exploiting both the good properties of SAR in terms of high resolution and the good sensitivity of radiometric observations to soil moisture. Signatures collected by Aquarius instrument mounted on the SAC-D satellite, although dedicated to ocean applications, are also used to investigate a joint use of active and passive L band observations over land, particularly in large homogeneous areas (Piles et al., TGRS, pp. 4700-4711, 2015).

Comparison of Sea Surface Salinity Retrieved from Spaceborne Radiometric Observations and Measured In Situ
Dinnat, E., Le Vine, D., Meissner, T., Boutin, J., and Martin, N. (11-Apr-16). Our presentation will report comparisons between SSS retrieved by SMOS and Aquarius, and comparisons between satellite SSS and in situ measurements. We will discuss the impact of the latest changes in the SMOS and Aquarius processing on the retrieved SSS and the differences between both instruments. The impact of differences in the retrieval algorithms (e.g. dielectric constant, ancillary sea surface temperature, surface roughness model, Faraday rotation) on the differences in SSS will be analyzed. If the maturity of the SSS retrieval algorithm for SMAP permits, we will also report first comparisons of SMAP SSS with other satellite SSS and in situ data.

Impact of Atmospheric Boundary Layer Stability on Ocean Emissivity at L-Band: Understanding Regional and Seasonal Salinity Biases in Aquarius Data
Brown, S., and Misra, S. (11-Apr-16). The correction for wind-driven rough surface emission is one of the largest corrections that are required for satellite based sea surface salinity (SSS) retrieval. Missions such as SMOS, Aquarius and SMAP use models that describe the excess emission as a function of wind speed to remove this signal from the data in order to accurately estimate the sea water dielectric and hence SSS. Several studies have shown boundary layer stability is a key factor in air-sea interaction, including wave and foam formation and that wind speed alone may not be sufficient to describe the excess emission of the ocean.

L-Band Radiometers Inter Calibration over Natural Targets
Cabot, F., and Anterrieu, E. (11-Apr-16). Since the launch of the SMOS mission in 2009, two other satellites carrying L-band radiometers joined it on orbit. Aquarius was launched in June 2011 and SMAP in January 2015. Unfortunately, Aquarius ceased operation later that year. All 3 instruments have been operating simultaneously between April and June 2015. Although this golden age of L-band on orbit radiometry was short lived, it allowed for sound comparison of the performances of these 3 radiometers. Moreover, its untimely termination emphasizes the need for reliable inter calibration to build long term consistent archives of brightness temperature and higher level products.

Multi-Scale L-Band Brightness Temperature Analysis for Soil Freezing and Thawing Process Study
Roy, A., Royer, A., Derksen, C., Toose, P., Brucker, L., Mialon, A., Lanlois, A., and Kerr, Y.H. (11-Apr-16). Snow and frozen ground play a crucial role in climatological and hydrological processes, and are key factors in modulating energy, water, and carbon budgets. L-band space-borne missions such as Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS), and Aquarius have the potential to provide enhanced information on the surface freeze/thaw (F/T) state over northern regions. It is a key parameter for studies of terrestrial hydroclimatology and ecosystem processes. In this presentation, we first present an analysis over Canadian sites of the L-band brightness temperature (TB) variations from SMOS, Aquarius and first SMAP data in order to characterize the freeze/thaw (FT) soil state, including in winter when a dry snow cover exists.

Sea Ice Thickness Retrievial at L-Band: Comparison Between Results from Aquarius and SMAP Data
de Matthaeis, P. (11-Apr-16). Passive microwave measurements from the Soil Moisture Ocean Salinity (SMOS) mission, operating in the L-band at a frequency of 1.41 GHz, have been used to retrieve sea ice thickness with promising results, and a daily data product is now available from the Integrated Climate Data Center of the University of Hamburg. The purpose of this work is to apply a similar technique to measurements from two other L-band passive instruments, Aquarius and SMAP. Aquarius is a NASA sensor flown aboard the Argentinean SAC-D spacecraft and also operating at L-band.

Status of Aquarius and the Salinity Retrieval
Le Vine, D., Dinnat, E., Meissner, T., Wentz, F., and Lagerloef, G. (11-Apr-16). Aquarius is a radiometer/scatterometer combination specifically designed for remote sensing of sea surface salinity. The instrument was lost on June 7, 2015 when a power failure on the satellite resulted in loss of control of the observatory. This paper will report the plans for the mission and data processing and the status of the validation of the SSS data against Argo measurements.

Vegetation Optical Depth and Scattering Albedo Retrieval Using Time Series of Dual-Polarized L-Band Radiometer Observations
Konings, A., Entekhabi, D., Piles, M., and McColl, K. (11-Apr-16). Passive microwave measurements have the potential to estimate vegetation optical depth (VOD), an indicator of aboveground vegetation water content. They are also sensitive to the vegetation scattering albedo and soil moisture. In this work, we propose a novel algorithm to retrieve VOD and soil moisture from timeseries of dualpolarized L-band radiometric observations along with time-invariant scattering albedo. The method takes advantage of the relatively slow temporal dynamics of early morning vegetation water content and combines a number of consecutive observations to estimate a single VOD.