Meeting and Connection Info:
Meetings are held on Wednesdays, at 0800PT/1100ET/1700FR
https://stanford.zoom.us/j/801343415
Telephone:
Dial: +1 646 558 8656 (US Toll) or +1 408 638 0968 (US Toll)
Meeting ID: 801 343 415
Past meetings:
Feb 7, 2018
Recent Plots:
Recent progress towards matching observed and simulated transmission ratios at different airmasses (plot from AG)
Parameters are :
mol_modify H2O 4. MM
aerosol_default
aerosol_angstrom 1. 0.02
mol_modify O3 270 DU
aerosol_modify tau550 set 0.02
- Same parameters, but with no aerosol :
Ratios (Obs_Z_2 / Obs_Z_1) /(Sim_Z_2 / Obs_Z_1) :
Comparing the SEC(z) approximation to the approximating function described in Kasten & Young, Appl. Opt. 28, 4735-4738 (1989). The Y-axis in the following plot is the Kasten & Young approximation(z) - SEC(z). Plot from NM.
Although the actual change in airmass between the two is small, the change in the regression to zero airmass is quite striking... Plot from NM.
In an effort to figure out how sensitive we are to airmass perturbations, I applied a unique N(mu=0,sigma=0.0005) offset to every airmass (calculated using SEC(z)), then regressed that set of delta mag - airmass' to zero airmass. The results are plotted below. The red is the above regression, done using the "correct" SEC(z) airmass. The black curve is the mean of 100 realizations of this process, and the shaded region is +/- 1 standard deviation. I've re-run this a few times, and seen the black curve shift (mostly on the blue end), so I wouldn't take this as set in stone, more as a warning that we are quite sensitive to the question of "what is the SZA-airmass mapping". The Y-axis is cut off, but it is delta_mag@X=0.
