Figure 1.

Locations of Northeast Corridor (NEC) established tower-based observations, corresponding to Table 1. The red rectangle indicates the modeling analysis domain. Light grey shading indicates census-designated urban areas, yellow lines are interstate highways, and black boundaries are state lines, with a thinner black line showing the City of Baltimore. Green triangles indicate regional sites, red triangles indicate urban sites, and blue triangles are more rural or background sites surrounding the Washington–Baltimore domain. (a) Regional map. (b) Inset focusing on Washington, DC, and Baltimore, MD. All map data layers were obtained from either Natural Earth (http://naturalearthdata.com, last access: 23 March 2020) or U.S. Government sources (http://www.census.gov, last access: 23 March 2020) and are in the public domain.