Descriptor File Structure ========================== This file contains microphysical specifications for all hydrometeors. It includes central parameters for PSD, m-D, A-D relation and selection of scattering model for frozen hydrometeors. All values (e.g. a and b parameter for m-D relation) have to be provided in SI units. The descriptor file consists of the following fields ================= ============================= ================================================ *field* *values* *description* ================= ============================= ================================================ name string name of the hydrometeor as\_ratio positive float aspect ratio of hydrometeor. <0 means oblate. Note that mie-sphere, liudb and rayleigh do not consider as_ratio when estimating the scattering properties. liq\_ice -1, 1 Phase of hydrometeor, -1 is ice, 1 is liquid rho\_ms positive float Density of hydrometeor (ice only) a\_ms positive float 'a' parameter of mass-size relation (ice only) b\_ms positive float 'b' parameter of mass-size relation (ice only) alpha positive float 'alpha' parameter of cross section area-size relation (ice only). Only required for the advanced radar simulator. beta positive float 'beta' parameter of cross section area-size relation (ice only). Only required for the advanced radar simulator. moment\_in 0,1,2,3,12,23,13 Moment provided in input file (see below) nbin positive int Number of discrete size bins (internally, always nbin+1 is used) dist\_name str Name of hydrometeor distribution (see table below) p\_1 float 1st parameter of hydrometeor distribution (see table below) p\_2 float 2nd parameter of hydrometeor distribution (see table below) p\_3 float 3rd parameter of hydrometeor distribution (see table below) p\_4 float 4th parameter of hydrometeor distribution (see table below) d\_1 positive float minimum diameter d\_2 positive float maximum diameter of size distribution (not required for mono-disperse distribution) scat\_name string Scattering model. For passive and active, it can be "disabled" for disabling the specific hydrometeor, "mie-sphere", "tmatrix" (very slow), "liudb%P", and "hongdb%P". For active only: "rayleigh", "rayleigh-gans", "ss-rayleigh-gans\_%k\_%b". %P is for the particle type of the Liu or the Hong database (00 to 10) as described in their publications (see PAMTRA publication), %k and %b are for the kappa and beta parameter of the self similar Rayleigh Gans approach. If not provided, default values kappa = 0.19 and beta = 0.23 are used. vel\_size\_mod string Used model to estimate the fall velocity of hydrometeors. Can be 'khvorostyanov01_drops' (recommended for liquid), 'khvorostyanov01_spheres', 'rogers_drops', 'heymsfield10_particles' (recomended for ice and snow), 'khvorostyanov01_particles', 'rogers_graupel', 'powerLaw_%A_%B', 'corPowerLaw_%A_%B' (with pressure correction). %A and %B are teh parameters of the power law v(D) = %A*D^%B. Only required for the advanced radar simulator. canting float Canting angle of hydrometeors. Only for Tmatrix and (Self similar) Rayleigh Gans. The latter accept only values of 0 and 90deg. ================= ============================= ================================================ The complete list of options which can be used to define the PSD is given in table below. The table should be used as follows: given a distribution dist_name and a set of the parameters p_1 to p_4, moment_in describes the available choices for the moments of the PSD that have to be included in the input\_file. 1 means the total number concentration, 2 the effective radius, 3 the mass concentration, 13 both number and mass concentration and so on. d_1 and d_2 describe the diameter of the smallest and largest particle considered to calculate absorption and scattering properties for a given class of hydrometeors. =============== =============== =============== =============== =============== ============== =============== =============== **dist\_name** **p\_1** **p\_2** **p\_3** **p\_4** **moment\_in** **d\_1** **d\_2** =============== =============== =============== =============== =============== ============== =============== =============== mono -99 -99 -99 -99 1 or 3 d\_1 -99 mono N_T -99 -99 -99 2 or 3 -99 -99 mono\_cosmo -99 -99 -99 -99 3 -99 -99 exp N_T -99 -99 -99 2 or 3 d\_1 d\_2 exp -99 R_eff -99 -99 1 or 3 d\_1 d\_2 exp -99 -99 N_0 -99 1, 2, or 3 d\_1 d\_2 exp -99 -99 -99 -99 12, 13, or 23 d\_1 d\_2 exp\_field\_t -99 -99 -99 -99 2 or 3 d\_1 d\_2 exp\_field\_tq -99 -99 -99 -99 3 d\_1 d\_2 exp\_ryan -99 -99 -99 -99 1 or 3 d\_1 d\_2 logn N_T -99 sigma -99 2 or 3 d\_1 d\_2 logn N_T R_eff -99 -99 3 d\_1 d\_2 logn -99 R_eff sigma -99 1 or 3 d\_1 d\_2 logn -99 -99 sigma -99 12, 13, or 23 d\_1 d\_2 mgamma N_T -99 mu gamma 2 or 3 d\_1 d\_2 mgamma -99 R_eff mu gamma 1 or 3 d\_1 d\_2 mgamma -99 -99 mu gamma 12, 13, or 23 d\_1 d\_2 =============== =============== =============== =============== =============== ============== =============== =============== Note that it is also possible to provide discrete vectors for particle size concentration, mass, cross section area, density, and aspect ratio. See :any:`addFullSpectra` of the class :any:`pamDescriptorFile`. An exemplary descriptor\_file for a simulation with two hydrometeors is given in the table below. For the first hydrometeor category named cwc_q, the log-normal distribution have been used with a sigma of 0.38, fixed for the whole simulation via the parameter p\_3. Since the hydrometeor is in liquid phase, the density and the a and b parameters of the mass-size relation will be ignored. The aspect ratio and canting angle has been set to missing value (-99) because single scattering properties are calculated with Mie theory assuming spherical particles. The second hydrometeor swc_q is used to simulate snow. In this case an exponential distribution is used with a temperature dependent intercept parameter. The thermodynamic state of the atmospheric columns included in the simulation and the surface properties are provided via the input\_file (IF), which can be in ascii or net-cdf format. The minimum set of parameters that has to be included for clear sky simulations are: surface temperature, longitude, latitude, date and profiles of temperature, pressure, height and relative humidity. In case of cloudy profiles, the moments of the PSD specified in the descriptor\_file need to be included. The PAMTRA model gives as output TB for 2 observational heights, one is fixed at ground and the other can be specified in the IF for each profile. ========= =============== ============== ============= =========== =========== =========== ========== ================ ========== ================ ========== ========== ========== ========== ============ ========== ================ ========================= ================== **name** **as\_ratio** **liq\_ice** **rho\_ms** **a\_ms** **b\_ms** **alpha** **beta** **moment\_in** **nbin** **dist\_name** **p\_1** **p\_2** **p\_3** **p\_4** **d\_1** **d\_2** **scat\_name** **vel\_size\_mod** **canting** ========= =============== ============== ============= =========== =========== =========== ========== ================ ========== ================ ========== ========== ========== ========== ============ ========== ================ ========================= ================== cwc\_q -99. 1 -99. -99. -99. -99. -99. 23 100 logn -99. -99. 0.38 -99. 1.e-12 1 .e-2 mie-sphere khvorostyanov01\_drops -99. swc\_q -99. -1 -99. 0.038 2.0 0.3971 1.88 3 100 exp\_field\_t -99. -99. -99. -99. 0.51e-10 2 .e-2 mie-sphere heymsfield10\_particles -99. ========= =============== ============== ============= =========== =========== =========== ========== ================ ========== ================ ========== ========== ========== ========== ============ ========== ================ ========================= ==================