InMAP evaluation - Bay Area NGC emission scenario

This issue is opened to archive discussions on a test case for InMAP performance evaluation.

Contributions of the Bay Area natural gas combustion (NGC) emissions to ambient concentrations of PM2.5 (and its components) were estimated by InMAP and compared to those by CMAQ. CMAQ calculated the contributions by the brute-force method (BFM) which involved two model simulations: the base case where all emissions were present and the control case where the Bay Area NGC emissions were zeroed out.

The Bay Area NGC emission scenario was selected because:
1. CMAQ estimates of the impacts are already available
2. "[InMAP's] performance should be evaluated in terms of predicting marginal changes in concentrations rather than total ambient concentrations." ([Tessum et al., 2017](https://doi.org/10.1371/journal.pone.0176131))