Goulburn River experimental catchment data set

897

414

Abstract. In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, longterm time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations measuring soil moisture, in particular on a continuous basis, is still limited and the data they provide lack standardization of technique and protocol.

Section: Oznetmentioning

confidence: 99%

The International Soil Moisture Network: a data hosting facility for global in situ soil moisture measurements

Dorigo

Wagner

Hohensinn

et al. 2011

897

414

“…In situ soil moisture measurements used for comparison with the estimates from AMSR-E, ASCAT and Noah, include observations from the: -OZNET network in south-east Australia (Young et al, 2008;Rüdiger et al, 2007); Martínez-Fernández and Ceballos, 2005);…”

Section: In Situ Measurementsmentioning

confidence: 99%

Developing an improved soil moisture dataset by blending passive and active microwave satellite-based retrievals

Liu

Parinussa

Dorigo

et al. 2011

608

437

Abstract. Combining information derived from satellitebased passive and active microwave sensors has the potential to offer improved estimates of surface soil moisture at global scale. We develop and evaluate a methodology that takes advantage of the retrieval characteristics of passive (AMSR-E) and active (ASCAT) microwave satellite estimates to produce an improved soil moisture product. First, volumetric soil water content (m 3 m −3 ) from AMSR-E and degree of saturation (%) from ASCAT are rescaled against a reference land surface model data set using a cumulative distribution function matching approach. While this imposes any bias of the reference on the rescaled satellite products, it adjusts them to the same range and preserves the dynamics of original satellite-based products. Comparison with in situ measurements demonstrates that where the correlation coefficient between rescaled AMSR-E and ASCAT is greater than 0.65 ("transitional regions"), merging the different satellite products increases the number of observations while minimally changing the accuracy of soil moisture retrievals. These transitional regions also delineate the boundary between sparsely and moderately vegetated regions where rescaled AMSR-E and ASCAT, respectively, are used for the merged product. Therefore the merged product carries the advantages of better spatial coverage overall and increased number of observations, particularly for the transitional regions. The combination method developed has the potential to be applied Correspondence to: Y. Y. Liu (yi.y.liu@csiro.au) to existing microwave satellites as well as to new missions. Accordingly, a long-term global soil moisture dataset can be developed and extended, enhancing basic understanding of the role of soil moisture in the water, energy and carbon cycles.

“…More recently, a number of soil moisture networks were developed, e.g. the Goulburn River experimental catchment in Australia (Rüdiger et al, 2007) or SMOSMANIA (Soil Moisture Observing System -Meteorological Automatic Network Integrated Application, Calvet et al, 2007;Albergel et al, 2008) in Southwestern France.…”

Section: Introductionmentioning

confidence: 99%

An evaluation of ASCAT surface soil moisture products with in-situ observations in Southwestern France

Albergel

Rüdiger

Carrer

et al. 2009

188

115

Abstract.A long term data acquisition effort of profile soil moisture is currently underway at 13 automatic weather stations located in Southwestern France. In this study, the soil moisture measured in-situ at 5 cm is used to evaluate the normalised surface soil moisture (SSM) estimates derived from coarse-resolution (25 km) active microwave data of the AS-CAT scatterometer instrument (onboard METOP), issued by EUMETSAT for a period of 6 months (April-September) in 2007. The seasonal trend is removed from the satellite and in-situ time series by considering scaled anomalies. One station (Mouthoumet) of the ground network, located in a mountainous area, is removed from the analysis as very few ASCAT SSM estimates are available. No correlation is found for the station of Narbonne, which is close to the Mediterranean sea. On the other hand, nine stations present significant correlation levels. For two stations, a significant correlation is obtained when considering only part of the ASCAT data. The soil moisture measured in-situ at those stations, at 30 cm, is used to estimate the characteristic time length (T ) of an exponential filter applied to the ASCAT product. The best correlation between a soil water index derived from AS-CAT and the in-situ soil moisture observations at 30 cm is obtained with a T -value of 14 days.