Observed data-based assessment of relationships among soil moisture at various depths, precipitation, and temperature.

摘要

Soil moisture varies notably over different spatio-temporal scales and affects land-surface atmospheric interactions. However, globally, there is nearly a total absence in long-term observed soil moisture (SM) data. This study has used SM data from Nebraska and investigated relationships and potential predictability of SM at depths of 10, 25, 50, and 100 cm. It will show: (1) association between SM of 10 cm and 25, 50, and 100 cm, (2) relationship between maximum air temperature and SM at 10 and 25 cm depths, and (3) relationship between SM at various depths and precipitation. This investigation is completed for warm season (May-September) due to relatively active boundary layer. As expected, SM content is generally higher compared to the western locations following east-to-west decreasing precipitation gradient. Cross-correlations suggests that SM at 10 cm depths could be useful in estimating SM of 25 cm depths. The results show that positive and higher cross-correlation between 10 and 50 cm and 10 and 100 cm soils generally occurs earlier in wetter hydroclimatic conditions. Similarly, association between precipitation and SM at 10 and 25 cm is somewhat promising. A strong association is also found between SM at 10 and 25 cm and maximum temperatures. Comparatively, cross-correlation between SM and maximum temperatures were higher compared to SM and precipitation. Overall, results are promising and agree with previous studies.