Area Temperature Variation

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Idea: Place small temperature recorders at various locations throughout the Sitka area in an effort to achieve a better understanding of temperature variation on small spatial scales. In particular, it would be nice to investigate the effect of elevation, aspect, and distance from the main body of Sitka sound (i.e., up valleys, at the heads of bays, etc.).

Equipment: Use thermochron technology In particular, the iButton model DS1921G. Current price (3 September 08) $25.00 each for 1-24, $21.00 each for 25-99. Would be nice to get at least 25 to get the discounted rate.

These iButtons can be expected to last 10 years with temperature data recorded each hour for temperatures between -40C and 85C. Accuracy is said to be +/- 1C. Memory would fill up after 85 days, so sensors would need to collected and reset about once every 12 weeks. This could be done by taking a laptop (handheld computer of some sort?) into the field, or by swapping out iButtons and reading the data, with subsequent deployment to a different location.

In some instances it may be preferable to go for the DS2422 which is more accurate and can record observations for 48 weeks before memory runs out. These appear to cost about twice as much, however. Another possibility would be to record temperatures at longer intervals (every 90, 120, or 180 minutes, for example) to allow for a longer time before the memory fills up.

Locations: Accessibility is reasonably important, as well as the ability to address questions of interest. Initially it seems like 4 or 5 along Verstovia trail would be good, as well as another similar set up in Indian River valley (perhaps including recorders in each valley). I would also like to see the results from loggers set up from one end of the road system to the other, perhaps two or three miles, or so, intially. That would require 8-11, from Starrigavan to Green Lake Dam (including the endpoints). If there's enough devices, additional placements at a fixed elevation on Verstovia with different aspects would be nice to get. A related idea would be to do the same at sea level on a relatively large island such as Galankin or Middle Island (though cooperation of property owners would be required in those cases). Also locations around Sitka sound would be nice to get, though due to the increased expense and uncertainty of getting out on the water, it may be worth investing a bit more in one that can record hourly for 48 weeks before the memory fills up.

Deployment: Ideally, a standard protocol for deployment should be determined. In order to avoid effects due to burial by snow or direct sunlight, it seems like hanging the devices on the north side of a tree 6-8feet above ground level would be advisable, if at all possible. Additionally, GPS coordinates should be recorded, and photographs taken that can will allow someone to find the location in the even that one of the people who has previously visited that placement is unable to return (or forgets where exactly it was put). It may also be wise to obscure the visibility of the devices, especially in locations where it can be expected that others could wander, in order to avoid tampering.

Data: The data that is generated by this project will be made freely available on the Sitka Nature website for anyone who wants to see it. After several months to a year of data recording, it should be possible to begin to piece together an idea of the temperature variability in the Sitka area, though of course several years of data are better. It is likely that preliminary findings lead to ideas for better location choices, and locations can be changed or additional iButtons can be placed accordingly. The +/- 1C accuracy may not allow for very fine scale spatial variation in temperature, but hopefully it will be enough to be able to integreate the location and temperature information using GIS software in order to create temperature gradient maps for the local area and investigate how those might change seasonally. In the long run, it would also be nice to look at the relationship between vegetation and these temperature gradients.

Observations: Some first observations from Starrigavan.



Indian River

Harbor Mountain

Gavan Hill

57 04' 14.8 N 135 19' 25.4 W