Just in case some sees this post. i_parent_start and j_parent_start are the number of cells counted horizontally to the right and vertically up, respectively, from the lower left corner of the parent domain to the point where the nested domain starts. e_we and e_sn are the ending points of the grids, that is to say, the NUMBER OF CELLS (horizontally and vertically) THAT EACH GRID HAS.
Take a look at the figure in section "Creating Nested Domains with the WPS" from http://www2.mmm.ucar.edu/wrf/users/docs ... chap3.html
Also, you can't just assign a random number of cells to a nested domain, you have to make sure that it fits into its parent. The criterion to follow is that e_we and e_sw must be one greater than an integer multiple of the parent_grid_ratio (check section "How to add a new WRF geographical domain" from https://meteo.unican.es/trac/wiki/WRF4GTutorial2
Let me explain myself:
In your namelist.wps you have
parent_grid_ratio = 1, 3,
i_parent_start = 1, 36,
j_parent_start = 1, 14,
e_we = 100, 142,
e_sn = 67, 85,
This means that your nested domain starts at the 36th cell to the right and at the 14th cell to the top, starting from the lower left corner of the parent domain.
For the first (or parent) domain, e_we and e_sn have no restriction. For the second domain, parent_grid_ratio = 3, so e_we and e_sn must be one greater than a multiple of 3. And there you have 142-1=141 which is divisible by 3, and 85-1=84 which is also divisible by 3.
And Bob's your uncle!