We use this division of the NARCCAP domain for regional analysis.
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Zipfile containing masks
Masks are in netcdf format. There is a separate mask file for each region. The regions are defined on a half-degree lat/lon grid.
If you make use of these regions in research, please cite the regionalization as follows:
Bukovsky, M.S., 2011: Masks for the Bukovsky regionalization of North America, Regional Integrated Sciences Collective, Institute for Mathematics Applied to Geosciences, National Center for Atmospheric Research, Boulder, CO. Downloaded 2023-02-02.
This subregionalization was created to aid in the analysis of NARCCAP
simulations in subregions of the North American domain. It is, in
essence, a simplification of the terrestrial ecoregions provided in
Ricketts et al. (1999), and over the U.S. it closely follows the
regions used by NEON (National Ecological Observatory Network, Kampe
et al. (2010)). Eco-regions are sensitive to variations in temperature
and precipitation, and were judged to be a good proxy for areas of
similar regional climatology. Simplified eco-regions also capture
important features in regional climate; e.g. the Prairie region
captures the U.S. secondary summertime precipitation maximum, and the
DeepSouth region captures the eastern U.S. wintertime precipitation
maximum. Other climate classifications were also referenced in the
creation of this subregionalization (e.g. the Thornthwaite (1984) and
Köppen (1900) classifications), but they were generally too
complex in western North America, and too simplistic in eastern North
America. Simplification of the regions was necessary for ease of
analysis, but is also justified based on the resolution of the NARCCAP
simulations (50-km). Not all regions are fully based on eco-zones. The
Great Lakes region, for one, was shaped to cover most of the
appropriate watershed, and the Southwest was created to capture the
area of immediate influence by the North American Monsoon.
Ocean regions are based on Spalding et al. (2007), with some
simplification. For instance, the small area of Tropical Northwestern
Atlantic waters was combined with the Warm (Temperate) NW Atlantic
region. Ocean regions are also extended to reach the domain
This regionalization was done on a common 1/2 x 1/2 degree lat/lon
grid. Some of the regions overhang coastline because of the
resolution. A grid box with any percentage of land in it greater than
about 25%, after regridding and ensemble averaging the NARCCAP models'
land masks, was generally included in a terrestrial region. In some,
fully resolvable water regions (e.g. the Gulf of California) were
included with terrestrial regions to group together important
climatological processes. In waters that are prone to the formation of
sea ice in the winter, an effort was made to exclude a greater
percentage of the mostly water grid boxes from terrestrial regions, as
they can act significantly different than adjacent land.
Out of the 29 regions created in the NARCCAP domain, 13 (initial)
groupings have also been created for analysis over larger sub-regions
with similar characteristics.
Kampe, T.U., B.R. Johnson, M. Kuester, M. Keller, 2010. NEON: the
first continental-scale ecological observatory with airborne remote
sensing of vegetation canopy biochemistry and structure. J. Appl.
Remote Sensing, 4, 043510.
Köppen, W., 1900: Versuch einer Klassifikation der Klimate,
Vorzugsweise nach ihren Beziehungen zur Pflanzenwelt [Attempted
climate classification in relation to plant distributions].
Geographische Zeitschrift, 6, 593-611, 657-679.
Ricketts, T.H., and coauthors, 1999. Terrestrial ecoregions of North
America: A conservation assessment. Island Press, Washington, DC,
Spalding, M.D., H.E. Fox, G.R. Allen, N. Davidson, Z.Z. Ferdana,
M. Finlayson, B.S. Halpern, M.A. Jorge, A. Lomvana, S.A. Lourie,
K.D. Martin, E. McManus, J. Molnar, C.A. Recchia, and J. Robertson,
2007. Marine ecoregions of the world: A bioregionalization of coastal
and shelf areas. Bioscience, 57, 573-583.
Thornthwaite, C.W., 1984. An approach toward a rational classification
of climate. The Geographical Review, 38, 55-94.