I've done this sort of thing for 7 years using iButtons as levelloggers in vernal pools - ephemeral shallow ponds. I call my technique IButton stacks and I arrange them at 5 cm depth intervals, from the bottom of the pond to at least 20 cm over the maximum ponding depth, on t-posts that I install in the ponds. I program the iButtons to record temperature at 4 hour intervals specifically targeting the times of day when I expect the greatest dynamic differences in water vs air temperatures due to the high heat capacity of water. They are also installed on the posts so that the iButtons face south to maximize solar heat gain to again take advantage of the dynamic differences between air and water.
I'm headed out the door but will try to get back with some suggestions next week after I return. John ________________________________ From: Eliza Maher Hasselquist <[email protected]> To: [email protected] Sent: Friday, October 11, 2013 8:20 AM Subject: [ECOLOG-L] analyzing iButton temp data I have been using iButton temperature data loggers Hej ecologgers, I have been using iButton temperature data loggers as a low-cost way of determining inundation frequency in riparian zones. I'm hoping someone from ecolog will be able to give me some tips on how to process the data more efficiently. I have two data loggers which serve as references, one is always inundated (at the bottom of the stream) and one is in the air (about 1m high, and never inundated). I then attached loggers on the ground in the riparian zone at different distances from the edge of the stream. My plan is to determine inundation frequency of the different distances from the stream by comparing the reference loggers with the loggers on the ground. In theory, when the temperature of the ground loggers match the temperature of the water within 0.5C, then that location was inundated. If the ground logger matches the air within 0.5C, then that location was not inundated. I logged temperature every 4 hours. Sounds simple enough... But, I have two years of data, 22 streams, and 5 distances from the streams. This system is dominated by a spring flood, but summer and autumn floods are common. I've started going through and graphing the data and looking at it manually, but this is really time consuming. Also, because the loggers are on the ground, they often do not match the air temperature even if they are not inundated (cold air drainage, snow cover, etc.). Because of this, I thought about comparing the fluctuation of the temperatures - since diurnal and even daily fluctuations of the water is much less variable than the air. I have no idea how to do this, or if it makes sense to do. Any thoughts or suggestions would be really helpful. Thanks from Northern Sweden, Eliza Maher Hasselquist PhD student Umeå University
