Marc Schröder, Thomas Ruhtz, Eyk Bösche, Jürgen Fischer Institut für Weltraumwissenschaften

1. The airborne research platform of the FU Berlin: Overview of measurements taken during the BBC campaign and presentation of first products and analysis Marc Schröder, Thomas Ruhtz, Eyk Bösche, Jürgen Fischer Institut für Weltraumwissenschaften Freie Universität Berlin Germany

2. Table of contents • Overview of measurements • Calibration • BBC casi data catalog • casi cloudmask • Statistical characterisation of clouds

3. Overview of measurements Status ok ok, except for NIR ok no HMR since 20.09., GPS ok no Amount 54 G 2 G 9 M 4 G 0.5 G 1 G Instrument casi FUBISS classic HDRAD FUBISS extended HMR, G12 MIDAC Description Compact airborne spectrographic imager,nadir radiances (vis) FUB integrated spectrographic sys- tem (radiances): 1 nadir,1 zenith (vis), 1nadir (highvis), 1 nadir (NIR) Radiometer from the University of Heidelberg, 4 visible channels Irradiances (vis), nadir, zenith Flight attitude (20 Hz), GPS (10 Hz) Fourierspectrometer (5-17 m)

4. Calibration examplary results for FUBISS vis nadir spectral calibration absolute calibration

5. Calibration: Spectral comparison • Hintergrund • Radiative smoothing • (Bounded) cascade models • Multifraktalität time: 10.292 utc time: 10.223 utc • data taken from the 22.09.01 leg04

6. Calibration: Time series comparison wavelength: 753 nm • data taken from the 22.09.01 leg04

7. BBC casi data catalog • Hintergrund • Radiative smoothing • (Bounded) cascade models • Multifraktalität

8. BBC casi data catalog: Track overview Date: 010928 Leg: 02 start time stop time section length leg01 leg02 leg03 leg04 09:30:48 10:31:17 10km length: 28.69km / sections: 2 length: 30.22km / sections: 3 length: 29.27km / sections: 2 length: 57.11km / sections: 5

9. BBC casi data catalog: Images 34.2° casi altitude swath • top of image correspondes to • geograhpic north

10. casi cloudmask: Algorithm development define ratio: r = L(490 nm) / L(780 nm) • find thresholds: • cloud if r  rT and • cloud if L(490 nm)  LT(490 nm) casi nadir radiances, one received over cloud, the other over meadow, normalised to the respective radiance at 780 nm

11. casi cloudmask development:Thresholds histograms of casi nadir radiances at 490 nm and the ratio r, data from 13.09.01, leg5 thresholds: rT = 0.5 and LT(490 nm) = 60 Wm-2sr-1m-1

12. casi cloudmask development:Cloud shadow on clouds 23.09.01 pm, leg2 white: cloudmask with previous condition only gray: advanced cloudmas- king technique 2nd condition: rT  1.35 and LT(490 nm)  35 Wm-2sr-1m-1

13. casi cloudmask: Results I • data from 23.09.01 pm, leg6

14. casi cloudmask: Results II • data from 18.09.01, leg7

15. casi cloudmask: Results III • data from 22.09.01, leg1

16. Power spectra • data from 20.09.01, leg3 • cloud fraction b = 0.97 • Definition: • Scale invariance: • stationarity if • stationary incre- • ments if E(k) ~ |F(k)|2 314 m E(k) ~ k- =1.37 =2.52  < 1 1 <  < 3

17. Structure function analysis 1) (r;x) = (x+r) - (x) = i+r - i with i=1,...,N-r and N=L/l • Results for H(q) = (q) / q • small scales r: H(q=1) = 0.47 • large scales r: H(q=1) = 0.22 2) < |(r;x)|q > ~ (r/L)(q) with q0

18. Singulare measures 4) <[(r;x)]q> ~ (r/L)-K(q) with q0 1) (1;x) = (x+1) - (x) = i+1 - i with i=1,2,...,N-1 and N=L/l Results for C(q) = K(q) / (q-1) and C(q=1) = K´(q) |q=1 2) (1;x) = |(1;x)| / <|(1;x)|> with <|(1;x)|> = 1/(N-1)|(1;x)| • small scales r: C(q=1) = 0.11 • large scales r: C(q=1) = 0.07 3) (r;x) = 1/r  (r;x)

19. Summary • calibrated level 1b data for casi and FUBISS highvis, • shortly available: FUBISS vis (nadir, zenith) • delivered level 0b data to the IUP • BBC casi data catalog, available for each day • casi cloudmask, partly processed • statistical characterisation of clouds: to be completed • for days with high cloud fraction