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Document outlines approaches for extending LEM to handle: - Sedimentation: particles falling through S' field - Ice particle statistics: low multiplicity problem - Phase coupling: WBF process and S' fluctuations Five approaches analyzed with pros/cons: A) Phase-Separated LEM B) Spatial LEM (Fortran research code style) C) Lagrangian S' History (recommended) D) Conditional Statistics E) Hybrid approach Includes research questions and suggested starting point.
- collision.py: Remove hardcoded V_parcel=1.0 and rho_parcel=1.0, use actual parcel density/volume (collision rates were ~82x too high) - collision.py: Fix E_H80 interpolation to convert radius to microns (missing *1.0E6 disabled interpolation entirely) - collision.py: Fix kappa sequential mutation bug in same_weights_update and rewrite mass logic to match Fortran reference pattern - collision.py: Remove unnecessary hardcoded constants that shadowed function parameters - parameters.py: Fix N_l trailing comma that made it a tuple - parcel.py: Fix temperature sign logic for sine/oscillation modes (use T -= dz*g/cp unconditionally instead of checking w_parcel sign) - condensation.py: Fix dead wrong V_parcel formula (was 100/P/(R*T)) - analysis.py: Guard division by zero when no cloud droplets exist
- widget.py: nt_widget uses BoundedIntText (min=1, max=100000) - widget.py: sigma min 0.0→0.01, mu min 0.0→0.001 to prevent div-by-zero - print_plot.py: jet→viridis colormap (perceptually uniform) - print_plot.py: fix "Evaporaton" typo - print_plot.py: move deepcopy outside DSD loop (was re-copying every iteration) - print_plot.py: fig.show()→plt.show() for Jupyter compatibility - timestep_routine.py: add tqdm progress bar - timestep_routine.py: move time_array outside loop (was recomputed every step) - timestep_routine.py: remove unused pylab import
- animation.py: Replace clear_output()+fig.show() loop pattern with FigureWidget + batch_update for in-place updates (no memory leak) - animation.py: Only slice data up to current timestep (was sending full arrays) - aero_init.py: Remove unused scipy.stats.lognorm import
Presets (widget.py): - Maritime/Continental/Arctic dropdown auto-fills aerosol grid - Maritime: few hygroscopic CCN → fast rain onset - Continental: many small CCN → suppressed rain - Arctic: ultra-clean → extreme drizzle behavior Ablation Lab (widget.py + physics modules): - Kelvin (curvature) effect toggle: afactor=0 when off - Raoult (solute) effect toggle: bfactor=0 when off - Constant collision efficiency (E=1) vs Hall (1980) - Simplified terminal velocity (Stokes) vs Beard (1976) - ws_drops_stokes() added for pure Stokes drag comparison - All switches threaded through timestep_routine → physics modules Performance (@jit): - radius_liquid_euler: 0.2 µs/call with numba nopython - esatw: 0.1 µs/call with numba nopython - sigma_air_liq: JIT-compiled with cache - Removed unused scipy.optimize import
Port turbulent collision kernel (Ayala et al. 2008, NJP; Wang & Grabowski 2009, QJRMS) from SAM-LCM micro_coll.f90: - phi_w(), zhi_func(): helper functions for Ayala analytical model - gck(): general collection kernel with turbulent radial relative velocity and radial distribution function - E_turb(): turbulent enhancement factor lookup tables at epsilon = 100 and 400 cm^2/s^3 with bilinear interpolation - Ablation Lab toggle + epsilon widget in notebook
- Fix ZeroDivisionError when particles have M=0 or Ns=0 after collision (skip degenerate particles in condensation loop) - Add safety floor in Newton-Raphson solver for r_aero=0 and r_eul_old=0 - Add adaptive condensation substep option (Arnason & Brown 1971): dt_sub = min(2*tau_phase, dt) where tau_phase = 1/(4*pi*D_v*sum(A*r)/V) - New widget toggle in Ablation Lab + threaded through notebook
Fix Nc/Nr unit convention: multiply PyLCM values by rho to convert from /kg/1e6 to proper /cm3, matching Fortran output convention.
When p_crit > 1 in LSM, gamma = NINT(p_crit) collisions occur per pair instead of just 1. Includes limiter to prevent over-collection. Reduces PyLCM peak Nr from ~20 to ~6 /cm3 (Fortran: 2.2 /cm3).
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