Evaluation of Tb response to snowpack by multiple microwave radiative transfer models Do Hyuk “DK” Kang NASA Goddard Space Flight Center NPP Program by ORAU July 15 th 2015 NASA Postdoc Program NASA Goddard Space Flight Center

MEMLS, Mätzler and Wiesmann 1999 HUT, Pulliainen et al., 1999 DMRT, Tsang et al., 2007, Picard et al.,

Frolov and Marchert 1999, Hallikainen et al. 1986, TGRS

Coupled Model Kang and Barros 2010 Matzler and Wiesmann 1999

Coupled Model I : CLPX-1 Mass Balance Energy Balance

Coupled Model I : NoSREx-I II Mass Balance Energy Balance

CLPX

Schanda and Matzler 1981 Willis et al RS and Env Kang et al Published in IEEE

0.56 µm 36.5 GHz

Reflectivity discrepancy b/w microwave and visible/Infrared

Figure- Horizontally polarized TB responses at AMSR-E frequencies such as 6.9, 10.7, 18.7, 23.8, 36.5, and 89.0 GHz, evaluated by MEMLS, HUT, and DMRT-Tsang with increasing snow grain sizes.

Q) Why MEMLS and HUT are fast saturated with the snow grain sizes at 18.7 GHz compared with the HUT and DMRT-Tsang?

Q) Why DMRT-Tsang has a concave Tb response with snow grain sizes?

Figure- Vertically polarized TB responses at AMSR-E frequencies such as 6.9, 10.7, 18.7, 23.8, 36.5, and 89.0 GHz, evaluated by MEMLS, HUT, and DMRT-Tsang with increasing snow density from 100 to 700 kg/m 3.

Q) Why all 3 RTMs have increases with increase of snow density at 89 GHz?

z = epsaliceimag(fGHz,TK,Sppt) Q) Why all 3 RTMs have increasing curve with increase of snow density at 89 GHz?

Conclusions Forward model is a key to improve the inversion process for the earth features including snow Forward model can be decomposed to 1) snow physics and 2) RTM RTMs can be replaced with any model depending on a simulation of Tb, reflectivity, and scattering coefficient. 3 RTMs have been evaluated with gradual changes in snow physical properties

Prerequisites Statics, Dynamics: force Fluid Mechanics: pressure, geometry, and flux Engineering Mathematics: eigenvalue solution, matrix inversion, and wave equation Electromagnetic Waves: polarization, multi-layer Signal Processing: low, high pass filters, FFT

Top view of conical scan 30 Conical Scan rate: nominally 15 RPM, depends on altitude & airspeed for imaging without gaps Earth Incidence Angle 40 deg up from nadir Footprint size depends on altitude  Radar Min altitude 1500ft(457m): 200m dia.*  Radiometer Min alt 500ft(152m): 65m dia.*  Max altitude** ft(3353m): 1445m dia.  * geometric mean  ** ft if pressurized Full 360 deg scan yields 2 looks (fore & aft) of the surface 2 swath images (fore half-scan & aft half-scan) different fore vs. aft readings depending on target nature 12/5/2014Kim et al, SED seminar

Key Words Matzler and Wiesmann 1999 Devonec and Barros 2002 TbTb TsTs p ec freq LWC Brightness Temperature Absorption Coeffi. Scattering Coeffi. Real Permittivity Imaginary Permittivity

Matzler and Wisemann 1999 RS and Env

Frolov and Marchert 1999, Hallikainen et al. 1986, TGRS

Outline Concept: Radiative V.S. Snow Physical Variables Implementation: Coupled model between snow physics and forward model Application: Valdai Russia, CLPX Contribution: LWC & Snow grain size

Key Words Matzler and Wiesmann 1999 Devonec and Barros 2002 TbTb TsTs p ec freq LWC Brightness Temperature Absorption Coeffi. Scattering Coeffi. Real Permittivity Imaginary Permittivity

Matzler and Wisemann 1999 RS and Env

Model Setup State Variables (SWE [m], Snow depth [m], Snow density [kg/m 3 ], Snow Temperature [K], and Grain Size (will be) at each layer from 1st to nth layer 1-D Column simulation both for snow physics and radiation schemes with multi-layer Hourly Met. Data needed to drive model Output: Hourly Vertical Profiles of Snowpacks, Corresponding Tb [K], emissivity [ ], and Teff [K] Kang and Barros 2012 Part I and II

Site Descriptions Valdai, Russia, 78~83, SMMR, 25X25 km CLPX , 02~03, SSM/I, AMSR-E 25X25 km

Coupled Model I : Snow Physics Mass Balance Energy Balance

VALDAI

CLPX

Diurnal Cycle of Snow Physics Snow Temperature: Being tilted at 15:00 LST

Seasonal Cycle of Snow Physics Range of Snow Temperature and Density : Being narrowed in March 2003

Schanda and Matzler 1981 Willis et al RS and Env Kang et al Accepted in IEEE

Kang et al Accepted in IEEE

Kang et al Accepted in IEEE

Wiscomb and Warren 1980 VS Mätzler GHz = infrared 37 GHz = microwave

Ice-Lamellae Model (Mätzler 2000, DK imp.) Six flux theory: r, t, and e

Scattering: multi freq.

GPS + SNOTEL stations

Forward Simulators of Passive and Active Microwave.

Waveguide/free space method

Future Topics Grain size Ice lenses within snow layers Depth hoar/surface hoar First snow Intensity (radiative trnaser) Electric Dipole Moment Impedance Matching