Channelview Cogeneration Facility and Odyssey Energy Altura Cogen, LLC; 2. Deer Park Energy Center and Pasadena Power Plant; 3. Texas City Cogeneration, South Houston Green Power Site, and the "other" category. Equation shows the MLR model: the tropospheric vertical column density of GCAS is represented as an optimal combination of the CAMx VCD from the 10 contributing sectors with a residual given by ε. . In seeking an optimal match to the GCAS columns, it is important to apply a regularization term to prevent unphysical results . The optimal parameters (β) were determined by minimising the cost function in Equation . The residual ε is minimised subject to the regularization parameter λ applied to the magnitude of the scale factors (β). Equation 2 can be solved in a single Least Squares inversion . We applied the MLR model to the entire field campaign, and we also performed simulations separately for weekdays and for weekends.