Arancha Fidalgo's scientific contributions

Surface runoff is the water that flows after soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. When the soil is saturated and the depression storage filled, and rain continues to fall, the rainfall will immediately produce surface runoff. The Soil Conservation Service Curve Number (SCS-CN) method is widely used for determining the approximate direct runoff volume for a given rainfall event in a particular area. The advantage of the method is its simplicity and widespread inclusion in existing computer models. It was originally developed by the US Department of Agriculture, Soil Conservation Service, and documented in detail in the National Engineering Handbook, Sect. 4: Hydrology (NEH-4) (USDA-SCS, 1985). Although the SCS-CN method was originally developed in the United States and mainly for the evaluation of storm runoff in small agricultural watersheds, it soon evolved well beyond its original objective and was adopted for various land uses and became an integral part of more complex, long-term, simulation models. The basic assumption of the SCS-CN method is that, for a single storm, the ratio of actual soil retention after runoff begins to potential maximum retention is equal to the ratio of direct runoff to available rainfall. This relationship, after algebraic manipulation and inclusion of simplifying assumptions, results in the following equation given in USDA-SCS (1985): (P--0,2S)2 Q = (P + 0,8S) where Q is the average runoff (mm), P the effective precipitation (mm) and S is potential maximum retention (mm) after the rainfall event. The study has been applied to the Jucar River Basin area, East of Spain. A selection of recent significant rainfall events has been made corresponding to the periods around 22nd November, 2011 and 28-29 September and 10 October, 2012, from Jucar River Basin Authority rain gauge data. Potential maximum retention values for each point have been assumed as the first SMOS soil moisture values available at the closest DGG node immediately after saturation produced by the rain. The results are shown as maps of precipitation and soil moisture obtained using a V4 integration method between a linear and nearest neighbour methods. Surface runoff maps are consequently obtained using the SCS-CN equation given earlier. These results have also been compared to COSMO-CLM model simulations for the same periods. It is envisaged to obtain precipitation maps from MSG-SEVIRI data.

International Geoscience and Remote Sensing Symposium, Honolulu, Hawaii, July 2010 The main goal of ESA’s (European Space Agency) SMOS (Soil Moisture and Ocean Salinity) mission is to deliver global fields of surface soil moisture (SM) and sea surface salinity, with enough resolution to be used in numerical weather prediction and global climate models, usin g L-band (1.4 GHz) radiometry. Within the context of the preparation for this mission over land, the Valencia Anchor Station (VAS) experimental site, in Spain, was chosen as a preferential test sites in Europe for SMOS Cal/Val activities. Ground and meteorological measurements over the area are used as input to a Soil-Vegetation-Atmosphere-Transfer (SVAT) model, SURFEX (SURFace EXternalisé) - module ISBA (Interactions between Soil-Biosphere-Atmosphere) to simulate surface SM. Calibration as well as validation of the ISBA model was made by using in situ SM measurements.

Since 2001, the Valencia Anchor Station (VAS) is being used for validation activities in the context of low spatial resolution Earth Observation Missions such as CERES (Clouds and the Earth's Radiant Energy System), GERB (Geostationary Earth Radiation Budget), EPS (EUMETSAT Polar System), and is also being prepared for SMOS (Soil Moisture and Ocean Salinity). These missions have in common the low spatial resolution of their respective footprints (~50x50 km 2) and the necessity of a well characterised and instrumented large scale area. The VAS has been selected as a primary validation site by the SMOS Mission. The reasonable homogeneous characteristics of the area make this site appropriate to undertake the validation of SMOS Level 2 land products (soil moisture (SM) and vegetation water content) during the Mission Commissioning Phase. A control area of 10x10 km 2 was chosen to develop a network of ground SM measuring stations based on the definition of homogeneous physio-hydrological units attending to climatic, soil type, lithology, elevation, slope and vegetation cover conditions. The stations are linked via a wireless communication system to a central post accessible via internet. Area SM estimations are presently being compared to modelling products from ISBA – SURFEX. This paper shows the validation activities currently carried out at the VAS, especially the ESA SMOS Validation Rehearsal Campaign and the CNES CAROLS Scientific Airborne Campaign.