7 th SMOS Workshop, Frascati, October /17 AMIRAS campaign Fernando Martin-Porqueras

7 th SMOS Workshop, Frascati, October /17 Contents AMIRAS instrument and campaign L1 Processor Description of L1A, L1B and L1C processors Performances Examples Data format and availability

7 th SMOS Workshop, Frascati, October /17 AMIRAS instrument Small MIRAS instrument Y-shape 13 antennas: 4 LICEF per arm 1 NIR in the centre Angular resolution: 11.8 degrees Spatial resolution: 84 metres (altitude = 400 m) PMS of receiver B1 has to be repaired

7 th SMOS Workshop, Frascati, October /17 AMIRAS installation

7 th SMOS Workshop, Frascati, October /17 Location: Lahti, Finland Dates: June 20 th, 2006 (Flight1) – night Acquired data: Measurements over land, sea and fresh water (Lake Lohja) Duration: 1 hour 39 min Operation mode: Dual polarization AMIRAS Campaign – Flight 1

7 th SMOS Workshop, Frascati, October /17 Location: Lahti, Finland Dates: July 19 th, 2006 (Flight2) - night Acquired data: Measurements over land, sea and fresh water (Lake Lohja) AMIRAS Campaign – Flight 2 Duration: 2 hours 24 min Operation mode: Dual polarization Full polarization

7 th SMOS Workshop, Frascati, October /17 AMIRAS L1 Processor Snapshot Layer Instrument Characterization database Libraries L1B processor L1C processor L1C product Visibility Layer L1A processor Correlation layer Database reader Raw data

7 th SMOS Workshop, Frascati, October /17 L1A processor Scope: The computation of the denormalized visibilities Processing: Calibration algorithms are based on the SMOS In-Orbit Calibration documentation Input: Correlations, physical temperatures, PMS voltages, NIR output, instrument characterization database Output: Denormalized visibilities Differences with SMOS: Variable integration time (0.3 – 1.2 s) Centralized calibration Calibration based on internal load, cold sky and lake

7 th SMOS Workshop, Frascati, October /17 L1B processor Scope: The computation of the brightness temperature at the antenna polarization frame Processing: Input: Denormalized visibilities, instrument characterization database Output: Brightness temperature snapshots Inversion algorithm: Inverse FFT (Blackman windowing) Flat Target Transformation Antenna pattern correction

7 th SMOS Workshop, Frascati, October /17 L1B processor The processor implements the Flat Target Transformation (FTT) The FTT minimizes the impact of the antenna errors in the brightness temperature snapshots Location: Lahti Date: 19:43 UTC 20/07/2006 Orientation: Azimuth 180 deg Elevation 76.5 deg

7 th SMOS Workshop, Frascati, October /17 L1C processor Scope: The geolocation of the brightness temperatures over a fixed grid (UTM) on the surface and the computation of the polarization rotation angles Input: Brightness temperature snapshots, flight database Output: Brightness temperature geolocated, incidence and polarization rotation angles Differences with SMOS: No pixel-flagging Only AF-FOV Processing: Polarization rotation angle computation Geolocation using navigation information Incidence angle computation Velocity

7 th SMOS Workshop, Frascati, October /17 Radiometric Performances Radiometric performances estimated from L1B data Data used: 51 snapshots over the sea Assumptions: Constant flight dynamics along the dataset Unpolarized sea surface at 3 deg incidence angle Homogeneous sea surface Radiometric variability at boresight Radiometric accuracy = 1.5 K (1-sigma, 300 ms) = 2 K Equivalent radiometric variability in 1.2 sec = 0.75 K (1-sigma)

7 th SMOS Workshop, Frascati, October /17 Examples X polarizationY polarization Velocity

7 th SMOS Workshop, Frascati, October /17 Examples V - polarizationH - polarization Velocity

7 th SMOS Workshop, Frascati, October /17 L1C product content Planned data content: Time Position in UTM coordinates Incidence angle Brightness temperatures in the antenna polarization frame (X-Y) Polarization rotation angle between the antenna polarization and ground polarization frame Each UTM coordinate has different incidence angle availability x utm y utm Amount of data Velocity

7 th SMOS Workshop, Frascati, October /17 Data availability Release date: Christmas 2007 Distribution method: FTP Released data: L1C product from AMIRAS Flight1 Format: ASCII (data structure still on definition)

7 th SMOS Workshop, Frascati, October /17 On-going and future tasks L1C development Format definition for L1C Delivery Flight1 – dual polarization data (Christmas 2007) Delivery Flight2 – dual/full polarization data (March 2008) On-going tasks: Future tasks: