Uni Bonn contributions to SMOS Validation

1
Uni Bonn contributions to SMOS Validation

• Ralf Lindau
• Bonn University

2
Bonn contributions

• Detection of Radio Frequency Interference
• Found in SMMR, AMSR etc.
• Expected also in SMOS
• Comparison of SMOS soil moisture with existing
  data
• Direct measurements from GSMDB
• AMSR-derived SM
• Pixel-intern variance
• Necessary to interprete the intended validations
  with point measurements properly.
• build and operate a transportable polarized
  L-Band radiometer
• Investigate signal noise due to rain and
  vegetation

3
Radio Frequency Interference

• Time series of 6 GHz brightness temperature from
  SMMR in France
• Until 1981 the normal annual cycle is found.
• After 1981 the 6 Ghz signal is completely
  unusable due to noise.

4
SMMR RFI in 6 GHz
The scatter is low in Sibiria, increases westward
and reaches maximum values near St. Petersburg
5
ASMR RFI
In Europe the 10 GHz channel is completely noisy
in England and Italy.
In the USA the 6 GHz measurements are corrupted
over New York, Boulder etc.
6
AMSR 10 GHz RFI
250 K

• RFI is detectable by
• high monthly averages
• high monthly stddev.

300 K
7
Simple RFI Scheme

• TB gt 260 K
• Stddev gt 5 K
• DTB gt 20 K
• compared to a 10 x 30
• surrounding

8
Soil Moisture from AMSR
Longtime mean

10-day anomalies
9
2-Step Retrieval
10
Pixel-intern Variance

• Belarussian soil moisture data
• 21 stations, 10 daily during about 10 years
• Average spatially and compare the reduced
  variance to the total variance
• 40 are left for 400-km-Pixels
• 59 are left for SMMR-Pixels
• The left external variance is equal to the
  maximum correlation between point measurements
  and area averages