Specifics of 2DVar Module

• Univariate analysis

• Background error structures prescribed to stretch along contour lines of topography to some extent

• First guess field is the original first guess for the 3DVar taken locally at the first vertical level above the Eta steps

• 2DVar analysis increments replace those from the original 3DVar at the vertical level used to construct the 2DVar first guess field

• Main result

• With the modified assimilation system, surface temperature data have a non-negative impact on the model forecast.