Distinguishing between Unorganized and Organized Convection When Examining Land–Atmosphere Relationships

Abstract

Distinguishing between unorganized and organized convection when examining land-atmosphere relationships." Journal of Applied Meteorology and Climatology 54, No. 11 (Fall 2015 ABSTRACT In this study, the robustness of a previously developed classification system that categorizes convective thunderstorm events initiated during various synoptic and dynamic conditions is analyzed. This classification system was used to distinguish between organized and unorganized convection and then used to determine whether unorganized convection occurs preferentially over wet or dry soils. The focus is on 12 events that occurred in synoptically benign (SB) environments where the Great Plains low-level jet was not present (noLLJ), and whether these events were accurately classified as unorganized convection is evaluated. Although there is a small sample size, the results show that the classification system fails to differentiate between local unorganized convection and large-scale organized convection under SB-noLLJ conditions. The authors conclude that past studies that have used this classification to study how soil moisture influences unorganized convection should be revisited. Additional variables and/or alternative precipitation datasets should be employed to enhance the robustness of the classification system.

Evaluation of soil moisture in CMIP5 simulations over the contiguous United States using in situ and satellite observations

“…The North American Soil Moisture Database (NASMD; Quiring et al, 2016) provides quality-controlled daily soil moisture from approximately 1800 stations, most of which are located in the United States. NASMD has been used for validating the North American Land Data Assimilation System (NLDAS; Xia et al, 2015b, a) and examining the nature of land-atmosphere interactions (Ford et al, 2015b, c;Wang et al, 2015). There are numerous other studies that use in situ soil moisture from NASMD and ISMN.…”

Positive and Negative Surface Feedback and Atmospheric Control of Land Surface Conditions on Convective Organization Over the Tibetan Plateau

“…Cases with cloud area greater than 10,000 km 2 before convection triggering were discarded to reduce the impact of large‐scale weather systems. The thresholds used in previous studies on convection definition or classification are different, and it has been shown that the change of threshold will not significantly affect the results (Qiu & Williams, 2020; Schoen & Ashley, 2011; J. K. Wang et al., 2015). In addition, we also defined stronger convection (DC) with afternoon precipitation as in previous studies, which is defined as the day when the precipitation in the afternoon (12:00–18:00 LT) is higher than 1 mm and there is no precipitation in the morning (6:00–12:00 LT).…”

Observational Evidence of State‐Dependent Positive and Negative Land Surface Feedback on Afternoon Deep Convection Over the Southern Great Plains

“…By visual inspection, we found that most of the organized DC cases were propagating. Classification of different types of convective clouds was based on previous studies on storm classification and definition (Kumar et al, 2013;Schoen & Ashley, 2011;Wang et al, 2015); details of the classification method are in the supporting information. Sensitivity of the CTH > 6 km and area >3,600 km 2 thresholds has been tested, and results do not change with different thresholds (not shown).…”