Uncertainties the physical description of the atmosphere: distribution of CLW, WV; particle composition, size distribution, and shape.
No current method for validating MW scattering properties of ice-phase hydrometeors.
Present Retrieval Approach
Physical method using “consistency matching” -- adjust simulations until consistent with PMW and radar observations across multiple wavelengths (e.g., Meneghini, 1997).
Pros: Simple to implement, works equally over land and water
Cons: “matches” may not represent reality, geometric issues ignored (NUBF, beam matching)
Important note: the uncertainty due to unknown particle shape is orders of magnitude greater than other known sources of uncertainties.
B. Johnson IGARSS 2011 5/22
Retrieval Schematic (1) Radar-only Retrieval Large set of Radar-Retrieved Vertical Profiles of PSD/IWC Observed Reflectivities (Zku, Zka) Inversion Z-S, DWR, etc. Attenuation “Correction” (2) Forward Model Physical - Radiative Database Physical Model Precip. & Atmos. Hydrometeor Model Ext., Scat., p(Q), Z Radiative Transfer Model (3) Radar/Radiometer Retrieval Simulated Radiances (TBsim) TB Constrained PSD/IWC Profiles PMW Retrieval Algorithm Observed Radiances (TBobs) 6/22
Observed Reflectivities and Passive Microwave TBs during the 2003 Wakasa Bay Experiment B. Johnson IGARSS 2011 7/22
(Const. Density Spheres) Retrieval Inputs at each vertical level Environment: Pressure, Temperature, Humidity, Cloud Water Content Microphysics: Particle Density, Shape, PSD Type Observables: Zm,14, Zm,35, DWR Forward Dual Wavelength Ratio Retrieval Method Update PIA for air, clouds, and precip. (A14, A35) Starting at storm top (ztop) down to z=0 PIA-corrected Reflectivities Ze,14, Ze,35 B. Johnson IGARSS 2011 8/22 Match DWR with D0 (3.67/L) in Database; compute N0 Is DWR 1? no yes Ze,35-IWC retrieval, infer D0 / N0
WBAY 03: Dual Wavelength Ratio, and retrieved N0, and D0 (assuming a single constant particle density) B. Johnson IGARSS 2011 9/22