Characterization of the atmospheric aerosols and the surface radiometric properties in the AGRISAR Campaign

Transcription

1 Characterization of the atmospheric aerosols and the surface radiometric properties in the AGRISAR Campaign V. Estellés Solar Radiation Unit Universitat de València T. Ruhtz, P. Zieger, S. Stapelberg Institute for Space Sciences Free University Berlin L. Alonso, J. Moreno Laboratory Earth Observation Universitat de València

2 Objectives To perform a detailed characterization of physical and optical properties of aerosols in the atmospheric column for the atmospheric correction of airborne and satellite data. To collect ground radiometric spectra for both validation of airborne and satellite data and describe natural variability characteristics. Spectral measurements at leaf level were conducted for determining reflectance and transmittance. General

3 Objectives Measurement of solar direct and sky diffuse radiance at ground. Retrieval of surface radiometric spectra at ground and leaf level. Inmediate (completed)

4 Objectives Retrieval of columnar aerosol optical depth (AOD). Retrieval of spectral behaviour of AOD: Angström exponent. Retrieval of columnar water vapor (W) and columnar ozone (O3). Short term Retrieval of HYSPLIT backtrajectories for air mass characterization. (completed) Retrieval of surface /canopy reflectance and leaf reflectance and transmittance.

5 Objectives Determination of physical properties of aerosols: size distributions, effective radius and complex refractive index. Determination of optical properties of aerosols: single scattering albedo, phase function and asymmetry parameter. Mid term To analyze the characteristics of local aerosols in relation to: atmospheric profiles (soundings) and air masses origin (synoptic situation and backtrajectories). (in progress)

6 Instruments Sunphotometer Cimel CE318NE Sunphotometer Fubiss ASA2 Sunphotometer Microtops II Spectroradiometer ASD-FSFR

7 Cimel CE318NE Comercial sunphotometer Direct sun and diffuse sky radiance Channels 340, 380, 440, 500, 670, 870, 940, 1020, 1640 nm. FWHM 2 (UV) 40 (NIR) nm Postcalibration on July 2006

8 Cimel CE318NE Sun measurements 5-15 min Aerosol optical depth, columnar water content, Angström exponent Sky measurements 1 hour Size distribution, refractive index, single scattering albedo, phase function.

9 Fubiss ASA2 Prototype auto sunphotometer Direct sun and aureole radiance Channels 250 ( nm). Resolution < 10 nm. Pre calibrated on plane

10 Fubiss ASA2 Sun measurements msec Aerosol optical depth, columnar O3 content, columnar water vapor. Aur measurements msec Aureole index (aui) at 4º and 6º from the sun.

11 Microtops II Comercial sunphotometer Direct sun irradiance Channels 305, 312, 320, 940, 1020nm Resolution 2(UV) 10(VIS) nm. Accuracy 1 2% as compared to Brewer ozone retrievals.

12 Microtops II Sun measurements 15 minutes AOD at 1020 nm, columnar O3 content, columnar water vapor.

13 Demmin (supervised by Mr. Zabel) 18th April 5th June

14 Görmin 6th 10th June

15 3rd 8th July Görmin

16 ASD FSFR Comercial spectroradiometer Full spectral range nm Spectral sampling 1 nm Bandwidth 2.5 nm Radiometric calibration

17 ASD FSFR Standing measurement 5WR + 5TGT + 5WR Walking integration in long transects Determination of illumination stability Calculation of error in measurements Captures large scale variability Provides averaged values ~ pixel size ~8500 spectra collected for AgriSAR

18 Leaf Refl/Trans Fiber Optic Filter A new portable device has been built for field measurements of leaf reflectance and transmittance Successfully tested during AgriSAR field campaign Leaf Clip Dark Background Prepared for direct measurement of fluorescence emission

19 For AOD and α, a documented algorithm very similar to that of AERONET is used (Estellés et al., 2006). For W we apply the Bruegge et al. (1997) technique. SKYRAD v4 code will be used for the retrieval of other physical and optical properties. For the FUSS ASA2 instrument, the AOD and aureole index (aui) are obtained by the algorithm prepared by Paul Zieger et al. (2006) from FUB. Methodology

20 Results

21 AOD data

22 Angström data

23 CWV data

24 Fubiss ASA data

25 CE & ASA For coincident filter (500 nm) and dates, the rmsd is about 0.04.

26 CE & MTOPS Rmsd is about But for this filter the temperature dependence of mtops is not corrected.

27 June

28 Only Fubiss ASA data July

29 Products summary

30 Ground Radiometric Measurements: 06/06* 07/06 08/06 10/06* 440 B 222 C Fallow Concrete 230 W 04/07* 05/07* 06/ B 222 C Concrete Dry Grass Grass 250 W 101 R 102 SB 102 SB Date 06 June Optical Flight 07 June 08 June 10 June Optical Flight Target Concrete Wheat 230 Grass Corn 222 Sugar Beet 102 Concrete Rape 101 Sugar Beet 102 Fallow Barley 240 Wheat 230 Dry Grass Concrete Type Cross calibration Cal/Val Cal/Val Cal/Val Cal/Val Cal/Val Cal/Val Cal/Val Leaf Refl /Trans Cal/Val Cal/Val Cal/Val Cal/Val Cal/Val Notes at Farm at Soccer Field at Farm GPS failed Chl data Next to 130 with Thermal GPS failed Date 04 July Optical Flight 05 July Optical Flight 06 July Target Concrete Barley 440 Corn 222 Wheat 250 Corn 222 Sugar beet 102 Corn 222 Type Cross calibration Cal/Val Cal/Val Cal/Val Cal/Val Cal/Val Leaf Refl/Trans Leaf Refl/Trans Leaf Refl/Trans Notes at farm GPS failed GPS failed Scintillometer transect GPS failed Scintillometer transect Next to Bowen Scintillometer transect Soil moisture transect

31 CASI At-Surface Reflectance wheat Field 230, Flight Line P6 05-Jul ASD Wheat Field 250 Reflectance [%] Wavelength [nm] INTA/CASI Flights Number of passes Flight Lines 04/07/06 6 [P1;P6] 05/07/06 8 [P1;P6] P5, P6 repeated This image was georeferenced, atmospherically and geometrically corrected, spatial resolution of 1.5m/pixel, 288 spectral bands. 06/06/06 7 [P1;P6] P5 repeated

32 MERIS Full-Resolution Data 3 scenes for June and 2 scenes for July campaigns 106 FR scenes through AgriSAR (not in database) Id Product Mission Sensor Start Orbit Track 45 MER_FR Envisat MERIS : MER_FR Envisat MERIS : MER_FR Envisat MERIS : MER_FR Envisat MERIS : MER_FR Envisat MERIS : CHRIS Hyperspectral data available ID Date Acq. Angle Remarks 6BA0_Demmin_ May :20 MZA = -21 High quality 6D65_Demin_ * 04-Jun :32 MZA = 1 Cloud cover 6F81_Demin_ * 07-Jul :15 MZA = -22 High quality 6FA8_Demin_ Jul :38 MZA = 11 Cloud cover

33 CHRIS/Proba MERIS zoom Study Area MERIS FR 4-July CHRIS Mode 1 7-July

34 Conclusions Measurements of ground based solar direct and sky diffuse radiance were performed along most of the campaign by two main instruments (CE and ASA). Retrievals of basic aerosol properties and gaseous atmospheric components were completed and are available for use. A more detailed description of the aerosol physical and optical properties will be available under user request (once the new CE318 calibration is applied). Measurements of surface radiometric spectra at ground and canopy level were performed and are available for public use. MERIS and CHRIS images from the site have been provided.

35 Characterization of the atmospheric aerosols and the surface radiometric properties in the AGRISAR Campaign V. Estellés Solar Radiation Unit Universitat de València T. Ruhtz, P. Zieger, S. Stapelberg Institute for Space Sciences Free University Berlin L. Alonso, J. Moreno Laboratory Earth Observation Universitat de València

36 A 6 aureole E MMS1spectrometer F fiber cables G special apertures D sun tracker C 4 aureole B direct sun path