The Heated Condensation Framework. Part II: Climatological Behavior of Convective Initiation and Land–Atmosphere Coupling over the Conterminous United States

Ahmed B. Tawfik, Paul A. Dirmeyer, Joseph A. Santanello
2015 Journal of Hydrometeorology  
This is Part II of a two-part study introducing the heated condensation framework (HCF), which quantifies the potential convective state of the atmosphere in terms of land-atmosphere interactions. Part I introduced the full suite of HCF variables and applied them to case studies with observations and models over a single location in the southern Great Plains. It was shown in Part I that the HCF was capable of identifying locally initiated convection and quantifying energetically favorable
more » ... lly favorable pathways for initiation. Here, the HCF is applied to the entire conterminous United States and the climatology of convective initiation (CI) in relation to local land-atmosphere coupling (LoCo) is explored for 34 summers (June-August) using the North American Regional Reanalysis (NARR) and observations. NARR is found to be capable of capturing the convective threshold (buoyant mixing potential temperature u BM ) and energy advantage transition (energy advantage potential temperature u adv ) for most of the United States. However, there are compensating biases in the components of moisture q mix and temperature q*, resulting in low u BM biases for the wrong reason. The HCF has been used to show that local CI occurred over the Rocky Mountains and the southern Great Plains 35%-65% of the time. Finally, the LoCo process chain has been recast in light of the HCF. Both positive and negative soil moisture-convective feedbacks are possible, with negative feedbacks producing a stronger response in CI likelihood under weak convective inhibition. Positive feedbacks are present but weaker.
doi:10.1175/jhm-d-14-0118.1 fatcat:imip2w73cvfjpnjqx2uwszsf3y