Some considerations in using climate data from existing weather stations or installing stations for research in Baltimore and Phoenix Urban LTER sites

The cities of Baltimore, MD and Phoenix, AZ are at the center of two recently designated Long-Term Ecological Research (LTER) sites in the worldwide network. They have been chosen as the first Urban LTER's, with focus placed on ecosystem processes in and around urban environments. These two cities share being urban places, but have contrasting histories, land uses/covers, general climates, and widely differing ecosystems -- one in the humid eastern U.S. environment near an ocean coast; the other, land-locked in the SW U.S. Sonoran desert region. Some of the effects of these differences in creating urban-rural differences in air temperature regimes in the Baltimore and Phoenix regions were clearly demonstrated in an analysis using data from several existing Global Historical Climate Network sites in each region. However, work on that analysis also pointed out some specific challenges in meeting LTER mandates for weather and climate data in these two LTER's. The mandates indicate that climate data are to be observed and/or summarized and archived to be made available to urban ecologists who must focus on how urbanization affects ecosystem change over long periods of time. The challenges for this mandate that are discussed in this paper include: (a) representativeness of key stations, (b) the importance of recognizing the details of historical stations in the area, such as instrumentation, time interval of data, location shifts, local microclimate change around sites, etc., (c) placement of new sites for ecological applications, and (d) the recognition in the two cities of definitions of urban and rural lands.