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Tree measurements (Roscommon). Research objective: To compare modeled values of TB (using τ-ω model*) with airborne values of TB over heterogeneous tree-covered.

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Presentation on theme: "Tree measurements (Roscommon). Research objective: To compare modeled values of TB (using τ-ω model*) with airborne values of TB over heterogeneous tree-covered."— Presentation transcript:

1 Tree measurements (Roscommon)

2 Research objective: To compare modeled values of TB (using τ-ω model*) with airborne values of TB over heterogeneous tree-covered areas, and by doing this, to describe the influence of vegetation heterogeneity on various model parameters by showing errors for different % cover situations. To compare modeled values of TB (using τ-ω model*) with airborne values of TB over heterogeneous tree-covered areas, and by doing this, to describe the influence of vegetation heterogeneity on various model parameters by showing errors for different % cover situations. * Wigneron, J.-P., J.-C. Calvet, T. Pellarin, A. Van de Griend, M. Berger, P. Ferrazzoli, Retrieving near surface soil moisture from microwave radiometric observations: current status and future plans., Remote Sens. Environ., vol 85., pp , 2003.

3 Roscommon farm – tree areas Vegetation: Vegetation: Open-forest formation: Box, Ironbark & Black Cypress-pine. Open-heath understory: Sifton bush Soils: sandy Soils: sandy Litter: Litter: average layer height 0.5 cm average dry bulk density 0.15 ± 0.05 g/cm3 % Rock cover: high % Rock cover: high green line = approximate sampling route for moisture measurements black cross on line = ‘temperature measurement tree’

4 1. Temperature measurements Physical temperatures necessary for modelling L-band brightness temperatures Physical temperatures necessary for modelling L-band brightness temperatures Measurements (1 tree): Measurements (1 tree): Tair in canopy at 7.5m and 5m heights Ttree 2 cm under bark at 1.50m height (NE & SW) Tair at ground surface (W & E) Tsoil -2 cm (N & S) Tsoil -4 cm (N & S) Tsoil -50 cm (N & S) Materials: datalogger & thermistors made by Vrije Universiteit Amsterdam Materials: datalogger & thermistors made by Vrije Universiteit Amsterdam

5 Results (temperatures)  An example for measurements on the NE side of the tree during the last fortnight of NAFE. NB. Surface values during daytime give extremely high temperatures; thermistors should have been covered to shield from direct sunlight.

6 2. Moisture measurements (soil & litter) Soil & litter moisture sampled at approx. 15 points per day, twice a week (weeks 2, 3 and 4 of NAFE). Soil & litter moisture sampled at approx. 15 points per day, twice a week (weeks 2, 3 and 4 of NAFE). Soil moisture: needed as ground truth for comparison with L-band measurements Soil moisture: needed as ground truth for comparison with L-band measurements Hydraprobe measurements: soil moisture content & temperature of top 5 cm Hydraprobe measurements: soil moisture content & temperature of top 5 cm Litter: effect of litter (moisture) on L-band signal is not yet known, some indication that measurements could prove useful for further research Litter: effect of litter (moisture) on L-band signal is not yet known, some indication that measurements could prove useful for further research Same procedure used as for vegetation water content (‘grab’ & quadrant samples) Same procedure used as for vegetation water content (‘grab’ & quadrant samples)

7 Results (moisture) Seems as though litter dries first, then soil Seems as though litter dries first, then soil No spatial images available yet, will later be used to compare to soil moisture patterns from airborne data No spatial images available yet, will later be used to compare to soil moisture patterns from airborne data litter dry, soil drying up soil and litter wet after small rain but litter already starting to dry (most points < 2 vol%)

8 Tree photo’s Fish-eye photo’s of trees taken for possible further analysis & calculation of LAI (INRA Bordeaux/Vrije Universiteit Amsterdam) Fish-eye photo’s of trees taken for possible further analysis & calculation of LAI (INRA Bordeaux/Vrije Universiteit Amsterdam) Total of 15 photo’s taken on 7 th Nov in area around the ‘temperature measurement tree’ Total of 15 photo’s taken on 7 th Nov in area around the ‘temperature measurement tree’ Camera: Nikon Coolpix Fish eye FC-E8 Camera: Nikon Coolpix Fish eye FC-E8

9 List of available data Data typeMeasurement dates T-tree 7.5m1-24 Nov T-tree 5m1-24 Nov T-bark -2cm (NE)7-24 Nov T-bark -2cm (SW)7-24 Nov T-surf (W)1-24 Nov T-surf (E)7-24 Nov T-soil -2cm (N)1-24 Nov T-soil -2cm (S)1-24 Nov T-soil -4cm (N)1-24 Nov T-soil -4cm (S)1-24 Nov T-soil -50cm (N)10-24 Nov T-soil -50cm (S)10-24 Nov Soil moisture (tree areas)8, 10, 15, 17, 22, 24 Nov Litter moisture (tree areas)15, 17, 22, 24 Nov Fish-eye photo's trees7 Nov

10 Finally, Any questions, remarks or helpful ideas:

11 Litter/surface SM relationship

12 Emissivity/SM relationship


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