We use a Large Eddy Simulation (LES) model with a nested domain configuration (297 and 120 km wide) and an interactive land surface parameterization to simulate the complex population of shallow clouds observed on August 30, 2016 during the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign conducted in north-central Oklahoma. Shallow convective clouds first formed over southeast Oklahoma and then spread towards the northwest into southern Kansas. By the early afternoon, the relatively uniform shallow cloud field became more complex in which some regions became nearly cloud free and in other regions larger shallow clouds developed with some transitioning to deeper, precipitating convection. We show that the model reproduces the observed heterogeneity in the cloud populations only when realistic variations in soil moisture are used to initialize the model. While more variable soil moisture and to a lesser extend cool lake temperatures drive the initial spatial heterogeneity in the cloud populations, precipitation-driven cold pools become an important factor after 1300 CST. When smoother soil moisture variations are used in the model, more uniform shallow cloud populations are predicted with far fewer clouds that transition to deeper, precipitating convection that produce cold pools. An algorithm that tracks thousands of individual cumulus show that the more realistic soil moisture distributions produces clouds that are larger and have a longer lifetime. The results suggest that shallow and deep convection parameterizations used by mesoscale models need to account for the effects of variable land-atmosphere interactions and cold pools.
Fast, Jerome D., et al. "The Impact of Variable Land-Atmosphere Coupling on Convective Cloud Populations Observed During the 2016 HI-SCALE Field Campaign." Journal of Advances in Modeling Earth Systems, vol. 11, no. 8, Aug. 2019. https://doi.org/10.1029/2019MS001727
Fast, Jerome D., Berg, Larry K., Feng, Zhe, Mei, Fan, Newsom, Rob K., Sakaguchi, Koichi, & Xiao, Heng (2019). The Impact of Variable Land-Atmosphere Coupling on Convective Cloud Populations Observed During the 2016 HI-SCALE Field Campaign. Journal of Advances in Modeling Earth Systems, 11(8). https://doi.org/10.1029/2019MS001727
Fast, Jerome D., Berg, Larry K., Feng, Zhe, et al., "The Impact of Variable Land-Atmosphere Coupling on Convective Cloud Populations Observed During the 2016 HI-SCALE Field Campaign," Journal of Advances in Modeling Earth Systems 11, no. 8 (2019), https://doi.org/10.1029/2019MS001727
@article{osti_1605362,
author = {Fast, Jerome D. and Berg, Larry K. and Feng, Zhe and Mei, Fan and Newsom, Rob K. and Sakaguchi, Koichi and Xiao, Heng},
title = {The Impact of Variable Land-Atmosphere Coupling on Convective Cloud Populations Observed During the 2016 HI-SCALE Field Campaign},
annote = {We use a Large Eddy Simulation (LES) model with a nested domain configuration (297 and 120 km wide) and an interactive land surface parameterization to simulate the complex population of shallow clouds observed on August 30, 2016 during the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign conducted in north-central Oklahoma. Shallow convective clouds first formed over southeast Oklahoma and then spread towards the northwest into southern Kansas. By the early afternoon, the relatively uniform shallow cloud field became more complex in which some regions became nearly cloud free and in other regions larger shallow clouds developed with some transitioning to deeper, precipitating convection. We show that the model reproduces the observed heterogeneity in the cloud populations only when realistic variations in soil moisture are used to initialize the model. While more variable soil moisture and to a lesser extend cool lake temperatures drive the initial spatial heterogeneity in the cloud populations, precipitation-driven cold pools become an important factor after 1300 CST. When smoother soil moisture variations are used in the model, more uniform shallow cloud populations are predicted with far fewer clouds that transition to deeper, precipitating convection that produce cold pools. An algorithm that tracks thousands of individual cumulus show that the more realistic soil moisture distributions produces clouds that are larger and have a longer lifetime. The results suggest that shallow and deep convection parameterizations used by mesoscale models need to account for the effects of variable land-atmosphere interactions and cold pools.},
doi = {10.1029/2019MS001727},
url = {https://www.osti.gov/biblio/1605362},
journal = {Journal of Advances in Modeling Earth Systems},
number = {8},
volume = {11},
place = {United States},
year = {2019},
month = {08}}