Electromagnetic properties of ice and the problems of cryospheric remote sensing

1. Electromagnetic properties of ice and the problems of cryospheric remote sensing G.S. Bordonskiy Institute of Natural Resources, Ecology and Cryology SB RAS Butina str. 26, Chita, 672090, Russia lgc255@mail.ru

2. Is ice a simple medium? 6 GHz cavity measurements of fresh-water ice; double refractive index n1 and n2 observed near 0ºC.

3. n2 additional wave or “new” wave E n1 initial wave This effect was predicted by Nobel Prize Laureate V.L. Ginzburg and S.I. Pekar in Crystal Optics for media with spatial despersion. For media with spatial despersion tensor k – wave vector. l, distance

4. Oscillation of first Stokes parameter vs time March 2006, ice cover of fresh-water lake Arakhley, f=2.4Ghz

5. In general there are 4 waves with different wave vector k at two orthogonal polarization. Electromagnetic field structure (the amplitude envelopes) due to a superposition of two orthogonal and two additional waves (all having close but different wavelengths), which results in field interference along the x and y axes. The superposition of fields Ex and Ey specifies the field pattern at a distance from the source. There are some anomalies effects: : disappear signal at some distance (or time) : gain signal : anomalies of polarization state : …

6. 2 orbit 1 orbit a) a) radar measurements of underglaciar objects b) phase altimetry of ice cover c) radio sounding of crystal clouds etc b) c)

7. Phase of reflection coefficient from ice-air boundary strongly changed near 0ºC (measurements at 13.8 GHz)

8. If additional waves exist → brightness temperature of crystal cloud may pulsed.

9. Correlation coefficient of brightness temperature at 3.3mm and 8.5mm wavelengths of winter clouds, Chita region, 14 December 2006.

10. k1 k1 Ice Ice k2 k2 Vgr Vgr Vph1 Vph2 Vph1 Air Air b) a) Vph2 Possible cases of refraction of initial and additional waves at ice-air boundary: a) normal dispersion; b) negative dispersion. Vph – phase velocity, Vgr – group velocity, ki – wave vectors. Dotted line – refracted rays for usual media

11. Measurements of angle refraction

12. Plots of angle refraction for incident angle 30º at 2.3 cm wavelength for different polarization of receiving signal. Transmitted signal – at vertical polarization. Splitting of refraction angle is observed.

13. Antarctica: Radar interferometry. Jump of surface height – due to underglaciar river. Website ESA. 20 April. 2006.

14. Conclusions • There are anomalies of electromagnetic properties of ice at microwaves. These anomalies strongly affected on wave propagation in frozen media. • The anomalies connected with spatial dispersion of ice (i.e. dependence of dielectric permittivity tensor from wave vector). • One of the spatial dispersion effects is appearance of additional wave, which have another wave vector, but equal polarization with initial waves. • Additional waves led to interference pulsing of propagated radiation and changing of phase of reflection coefficient from a boundary. • It is necessary taken into account these effects at remote sensing of ice structures.

15. References • G.S. Bordonskiy, A.A. Gurulev, S.D. Krylov et. al.“New” Ginzburg-Pekar Waves in the Microwave Range in Ice. // Technical Physics, 2006, Vol. 51, No. 5, pp. 626-629. • Г.С. Бордонский, А.А. Гурулев Возможные ошибки при интерпретации данных радиозондирования ледяных покровов. // Исследование Земли из космоса. 2007. №4.