Table 2.
Details of ISMN networks used in this study.
| Network | Extent | Interval | Stations | Years | Days | SM Levels | Instruments |
|---|---|---|---|---|---|---|---|
| ARM | Local | Hourly | 29 | 22 | 7740 | 10 | 15 |
| AWDN | Local | Daily | 50 | 13 | 4749 | 4 | 2 |
| COSMOS | Regional | Hourly | 101 | 7 | 2308 | 1* | 1 |
| PBO-H2O | Regional | Daily | 108 | 8 | 2865 | 1* | 3 |
| SCAN | Regional | Hourly | 211 | 19 | 6877 | 24 | 52 |
| SNOTEL | Regional | Hourly | 415 | 19 | 6425 | 16 | 45 |
| SOILSCAPE | Regional | Hourly | 135 | 4 | 7256 | 29 | 6 |
| USCRN | Regional | Hourly | 114 | 15 | 5029 | 5 | 5 |
| USDA-ARS | Regional | Hourly | 4 | 8 | 2618 | 1 | 4 |
Local extent means the network spans parts of one (or for ARM, two) states; regional networks span many states, and often all of the conterminous US. Interval indicates typical interval – for some networks labeled “Hourly” some subset of instruments may report 3- or 6-hourly. Years and days indicate the smallest span that incorporates all data. Instruments indicates the sum of the maximums of the number of each unique type or uniquely labeled type of sensor deployed at any site. SM levels indicates the total number of unique depths of sensor placement for the network
indicates sensors that sit above ground and sense soil moisture remotely – the depth of the measurement is not static and varies with location, soil moisture and other conditions.