Observations of daily precipitation have been a part of GLOBE from the beginning. At the start, GLOBE’s participation model was that schools would take measurement following all of the original 17 protocols. Atmosphere temperature, precipitation, cloud, and soil moisture measurements were to be collected daily at a site easily accessible to the school. A permanent installation of an instrument shelter containing a max/min thermometer mounted to a post along with a rain gauge was the expected norm with other measurements taken nearby. Daily temperature and precipitation measurements were to be taken within one hour of local solar noon – a time expected to coincide with a school’s mid-day lunch break.
Beginning in about 2000, following the example of GLOBE implementation in the UK, this model of a school doing every protocol shifted to an expectation that teachers would implement those element of GLOBE that fit with their curricula. This has freed the protocols from the need to be grouped at a single site and a specific time of day except where there are specific science requirements (e.g., surface temperature and water transparency protocols require simultaneous cloud observations and max/min air temperature is still recorded measured within one hour of local solar noon).
Many GLOBE measurements may now be taken at any time of day. The rain and solid precipitation protocols still prefer daily observations and the accumulation times of daily observations must be 24 hours with one hour more or less acceptable. So, if a rain gauge is emptied and remounted at 9:10 AM, the next day the rainfall should be read between 8:10 AM and 10:10 AM. Accumulations of up to 7 days are still accepted, but daily observations are preferred whenever possible. Participants may choose the time of day that works with their schedules.
With overnight snowfall, measurements of daily accumulation may be better taken in the morning before sunshine and wind reduce the new snow amount. As an example, in the US and Canada, the Community Collaborative Rain, Hail and Snow (CoCoRaHS) network (https://www.cocorahs.org/) uses the same rain gauge that GLOBE uses, but their 24-hour observation period ends at 7:00 AM. Similar to GLOBE, data from CoCoRaHS gauges observed between 4:30 AM and 9:30 AM (local time) are still posted on their daily maps, and observations outside of this window are still accepted but not mapped. Now, precipitation observations may be reported to both programs. The GLOBE data system will sort measurements by time of day and offer visualization data planes for morning, within one hour of local solar noon, and afternoon observation times. Selecting all three data layers will allow all measurements for a given day to be shown on the map. I hope this increase in the flexibility of GLOBE implementation will significantly increase the reporting of precipitation measurements.
