TY - JOUR
T1 - The Importance of the One-Dimensional Assumption in Soil Moisture - Rainfall Depth Correlation at Varying Spatial Scales
AU - Holgate, C. M.
AU - Van Dijk, A. I.J.M.
AU - Evans, J. P.
AU - Pitman, A. J.
N1 - Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/3/27
Y1 - 2019/3/27
N2 - Inferring local land-atmosphere coupling through correlation of colocated soil moisture and future rainfall inherently assumes a one-dimensional (1-D) framing of the coupling mechanism. For the first time we demonstrate the importance of upholding this assumption by examining the statistical relationship between daily soil moisture and rainfall depths over Australia, specifying spatial scales (0.05°, 0.5°, 1°, and 2.5°) to constrain the relationship to local-only physical processes. At small scales, without consideration of the 1-D assumption, strong land-atmosphere coupling is suggested across much of the country. However, when adhering to a 1-D framework, small sample sizes make correlation unsuitable for assessing local coupling at these small scales. When adhering to a 1-D framework, at scales of 0.5° and above, we find positive correlations in northern Australia in the wet and transition seasons and negative correlations in southern Australia in austral winter. The correlation is scale dependent, suggesting that as spatial resolutions increase in the future and land-atmosphere coupling heterogeneity is resolved, spatial distributions of local coupling may differ from larger-scale estimates characteristic of current coarse resolution climate models.
AB - Inferring local land-atmosphere coupling through correlation of colocated soil moisture and future rainfall inherently assumes a one-dimensional (1-D) framing of the coupling mechanism. For the first time we demonstrate the importance of upholding this assumption by examining the statistical relationship between daily soil moisture and rainfall depths over Australia, specifying spatial scales (0.05°, 0.5°, 1°, and 2.5°) to constrain the relationship to local-only physical processes. At small scales, without consideration of the 1-D assumption, strong land-atmosphere coupling is suggested across much of the country. However, when adhering to a 1-D framework, small sample sizes make correlation unsuitable for assessing local coupling at these small scales. When adhering to a 1-D framework, at scales of 0.5° and above, we find positive correlations in northern Australia in the wet and transition seasons and negative correlations in southern Australia in austral winter. The correlation is scale dependent, suggesting that as spatial resolutions increase in the future and land-atmosphere coupling heterogeneity is resolved, spatial distributions of local coupling may differ from larger-scale estimates characteristic of current coarse resolution climate models.
UR - http://www.scopus.com/inward/record.url?scp=85062953247&partnerID=8YFLogxK
U2 - 10.1029/2018JD029762
DO - 10.1029/2018JD029762
M3 - Article
SN - 2169-897X
VL - 124
SP - 2964
EP - 2975
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
IS - 6
ER -