Dear GLOBE Soil Moisture and Temperature Sites,

Welcome back to school (for schools just coming back from a break)! I have several important updates to the GLOBE soil moisture and temperature protocols to bring to your attention. These changes will greatly improve this data set and provide your students with more interesting data sets to compare with other GLOBE data.

Required Changes

• Soil Water Content (SWC) should now be reported as a ratio of water lost during drying over dry weight, rather than as a dry weight percent (ie. do not multiply your values by 100). This was done to avoid confusion about the definition of percent. Your values should range between 0.01 and 0.50. Organic-rich soils might have higher values - please contact me if your SWC ratio is above one.
• Any schools making optional Gypsum block observations must now replace these sensors with Watermark sensors, which are more sensitive to soil moisture. The soil-sensor calaibration curve will also need to be re-derived. I still have some Watermark sensors to give away to schools making this measurement so contact me if you are interested.

• The Soil Temperature data logger pilot program has been extended for another year. Thus, if you are able to purchase an Onset Hobo 4 channel data logger and temperature sensors (~$185 from: www.onsetcomp.com) or equivalent unit, I urge you to measure air temperature at 1.5 m and soil temperature at 5, 10 and 50 cm every 15 minutes and ftp the data to me every 2 weeks. Please see the complete pilot protocol description at:
  • http://www.hwr.arizona.edu/globe/pilot/2000stsum.html
  Ten schools in the first-phase of the pilot collected some very interesting soil temperature data at hourly intervals. I encourage your to download some of it to challenge your students plotting, analysis and math skills. It is available as ASCII files from:
  • http://www.hwr.arizona.edu/globe/pilot/2000stdat.html

Sincerely,

Dr. Jim Washburne jwash@hwr.arizona.edu