geoland

Core Service bio-geophysical Parameter

Issue I.1.00

Ralf Lindau

UniBonn

CSP Meeting

9th September 2005

R&D Status reportR&D Status report

CSP Meeting, Lisbon, 9th September 2005

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Soil Moisture Retrieval for 2004

Global soil moisture fields for the second year (2004) are ready.

Resolution Half degree (50 km) 10 days

CSP Meeting, Lisbon, 9th September 2005

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Duero Basin

Time series for one grid point in Spain during 2003/2004.

Two years of data are now available for the TUW comparison in the Duero Basin.

CSP Meeting, Lisbon, 9th September 2005

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Two-step Retrieval

Longterm local mean of soil moisture (85.4 % of the total variance)

Longterm mean of precipitation Soil texture Vegetation density Terrain slope

Remaining anomaly against the longterm local mean

AMSR brightness temperatures (18 GHz, as 10 GHz is corrupted by RFI)

CSP Meeting, Lisbon, 9th September 2005

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Calibration of local longtime means by Russian data

Local longtime means of soil moisture comprise the majority of soil moisture variance (85.4%)

Local longtime means can be retrieved with high accuracy (r=0.854) from:

Climatological rain Vegetation density Soil texture Terrain slope

CSP Meeting, Lisbon, 9th September 2005

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Validation with Illinois Data

• On global scale the Illinois data set represents practically only one single site.

• However, this spot is retrieved accurately, lying on the 1-to-1 line.

CSP Meeting, Lisbon, 9th September 2005

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Chinese Soil Moisture Data

40 Stations

Measurements of 1m soil moisture for the period 1981 - 1999

CSP Meeting, Lisbon, 9th September 2005

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Validation with Chinese Data

• Underestimation of the mean soil moisture by 74mm. (200 mm / 274 mm)

• Correlation low with 0.523

• Mainly due to four desert stations.

CSP Meeting, Lisbon, 9th September 2005

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So far the validation of the longtime means (which include the majority of variance).

To improve the temporal performance, the availability of lower frequencies would be helpful, but they are disturbed by RFI.

CSP Meeting, Lisbon, 9th September 2005

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Radio Frequency Interference

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.

CSP Meeting, Lisbon, 9th September 2005

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Monthly 10 GHz Time Series

• RFI is detectable by

• high monthly averages

• high monthly stddev.

250 K

300 K

CSP Meeting, Lisbon, 9th September 2005

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Identification of RFI

Sea ≈ 90 K

Land ≈ 250 K

Coast : Transition with high

standard deviation.

RFI : Warmer than land.

Increased stddev.

CSP Meeting, Lisbon, 9th September 2005

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Spatial averaged TB over land

RFI is warmer than the normal land temperature.

We need to know the normal TB for each region.

Monthly averages over an area of 10° x 30°

CSP Meeting, Lisbon, 9th September 2005

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Simple scheme for RFI identification

• TB > 260 K

• Stddev > 5 K

• TB > 20 K

compared to a 10° x 30°

surrounding

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Next actions

Delivery of source codes

Delivery of soil moisture data for 2004

Improvement of the RFI indentification scheme and development of a RFI correction scheme to make the lower frequencies of AMSR usable.