John,
Optimally, daily measurments would be the best. But, we know that classrooms might not be able to afford that time of time committment.
You can take these samples in the early morning, each day, at approximately 9:00 A.M. local time (ideally within a 6 hour window – from 3 hours before to 3 hours after 9:00 A.M. local time) will allow for optimal comparison with the SMAP data as this is closer to the SMAP time of acquisition.
If you cannot take the measurements each day, you can use the LaRC Satellite Overpass Tool (http://cloudsgate2.larc.nasa.gov/cgi-bin/predict/predict.cgi) and take measurements when the satellite is more directly over your area. This tool is very technical. What you would look for after you put in your information is the section under (GMT for timing and Distance To Site) These will tell you the date and time and where the satellite will be.
If your class does not meet until later in the day (late morning or early afternoon), you can still take measurements using the SMAP Block Pattern Soil. All data that you take is valuable for the GLOBE Program and the SMAP Mission.
You can take measurments for as long as you would like. The more data, the better.
You can wait for the spring melt before you take the measurements. The SMAP Spacecraft just launched last Saturday, January 31, 2015. There are many tests that the SMAP team must do in order to start receiving real soil moisture data. This data will not be publicly available for 6-9 months after launch.
John Harlin:
How many days per week do we need to take measurements to be useful?
For how many weeks?
The ground is now covered in snow. Can we wait for it to melt off in spring? How many weeks/months/years would you want our measurements. What about school holidays?
Thanks,
John Harlin