ClimateWNA is a stand-alone MS Windows-based software package.

ClimateWNA covers western North America from west of longitude 100W and from 25
to 80N latitude. A scientific article will soon be submitted for peer review. 
However, published papers on earlier versions of the package (ClimateBC and 
ClimatePP) and the base data (PRISM) are available (see reference list). The 
main changes for ClimateWNA are the increase in area covered and additional 
derived climate variables.

ClimateWNA enables users to obtain selected monthly climate variables based on 
latitude, longitude, and elevation for any point in western North America. The 
data represent weather station climate and variables include maximum, minimum 
and average monthly temperature, total precipitation and a suite of annual 
derived variables such as degree days, frost free period, fraction of pre-
cipitation as snow, annual evaporation and climatic moisture deficit. Historic
climate data (1901-2006) and future possible climates from global climate 
models under various emission scenarios are available. The climate change 
scenarios include examples from the IPCC 4th Assessment Report.  Additional GCM
scenarios can easily be added to the data base and they will be made available
through the Pacific Climate Impacts Consortium.

ClimateWNA provides ready access to historical and future climate data at any 
resolution. However, that there are important limitations. The data represent 
weather station climate, i.e., a site well exposed to the regional weather 
systems, and are dependent on the accuracy and resolution in the PRISM data 
(Daly et al. 2008) that is the basis of the software. Thus, features such as 
rain shadows, temperature inversions, and slope and aspect effects are modeled 
at a scale of several kilometres, while lapse-rate driven temperature 
differences are represented at the scale hundreds of metres.  Small-scale 
climate features such as frost pockets, or local slope and aspect effects, 
and conditions within and under vegetation canopies and in streams are not 
represented. The user needs to know how these features modify the larger scale 
climate. The shorter the historical time interval of interest, the less 
reliable the climate surfaces; this is particularly the case for precipitation
(Mbogga et al. 2009).

Monthly temperature and precipitation 1961-90 normals for 2281 weather stations
across western Canada and the US and were compared with values predicted by 
ClimateWNA. Standard errors for predicted monthly temperature were similar 
across all months except for slightly higher errors for minimum temperatures 
in winter months. Error varied from 0.6 to 1.1C depending on the month and 
temperature variable. Monthly precipitation had a standard error of 3 to 10 mm.
Wang et al (2006) and Mbogga et al. (2009) provide more information of 
accuracy of previous versions of the software.

ClimateWNA does not produce maps but data produced by it in batch mode can be 
used to create maps. Examples of maps are available through the Pacific Climate
Impacts Consortium Regional Analysis Tool. This is a web-based tool designed to
analyze and display climate model data and provide access to gridded data
(www.pacificlimate.org).

The program runs in Windows XP and Vista. However, you may need to add a file
(COMCTL32.OCX) to your operating system that for some reason it has not been 
included on many computers. A copy is available through the web site. Users 
on managed systems such as the BC government will need permission to add it. 
It has been added to on some MoFR computers and so far the government's 
computer network has not been compromised.

Finally, we have tried to ensure that the software is free of bugs. Please 
report problems or errors to me or to Tongli Wang at UBC. Please note that the 
PCIC, UBC and MoFR web sites are the only official sites for ClimateWNA and 
ClimateBC information. We do not endorse any other sites that use these names.

References

Daly, C., M. Halbleib, J.I. Smith, W.P. Gibson, M.K. Doggett, G.H.
Taylor, J. Curtis and P.P. Pasteris. 2008. Physiographically sensitive mapping
of climatological temperature and precipitation across the conterminous United
States. Int. J. Climatol. (2008) DOI: 10.1002/joc.1688.

Hamann, A., and T. L. Wang. 2005. Models of climatic normals for genecology and
climate change studies in British Columbia. Agric. For. Meteorol. 128:211-221.

Mbogga, M., A. Hamann, and T. Wang. 2009. Historical and projected climate data
for natural resource management in western Canada. Agric.
For. Meteorol. 149:881-890.

Spittlehouse, D. L. 2006. ClimateBC: Your access to interpolated climate data 
for BC. Streamline Watershed Manage. Bull. 9:16-21.

Wang, T., A. Hamann, D. L. Spittlehouse, and S. N. Aitken. 2006.
Development of scale-free climate data for western Canada for use in resource 
management. Intl. J. Climatol. 26:383-397.