PhD Proposal: Chetan Gurung
Location
Physics : 401
Date & Time
May 1, 2024, 2:00 pm – 4:00 pm
Description
ADVISOR: Dr. Henrique Barbosa
TITLE: Quantifying the Environmental Controls on Convective Initiation in the Tropics using the WRF-ARW Model
ABSTRACT: Understanding and modeling atmospheric convection remains challenging because convective clouds form and organize at a wide range of spatial and temporal scales. Convection starts with shallow clouds that grow and aggregate over a couple of hours into congestus, which finally become deep convective clouds. This process depends on complex interactions between the surface, the boundary layer, the thermodynamics, and the circulation. Moreover, long-term, high-resolution observations are scarce, particularly in the tropics, hindering our understanding of the shallow to deep (STD) convective transition. This explains, in part, why climate models still fail to represent the diurnal cycle of precipitation. One way to better understand the physical mechanisms responsible for developing and organizing convection is to use cloud-resolving models, which can represent the scale of clouds and turbulent eddies.
In this study, we will perform high-resolution simulations of the STD transition to investigate its controlling mechanisms. The simulations will be carried over tropical regions such as the Amazon rainforest, the Congo rainforest, and the Pacific Ocean, and the results will be contrasted. We will use the Advanced Research WRF (WRF-ARW) regional model with a spatial resolution of about a few hundred meters to capture all scale's convective initiation. We will then impose perturbations in the atmospheric fields and observe the changes in the evolution of the cloud field, i.e., evaluate how each triggering mechanism affects the STD transition. We expect that this sensitivity analysis will help to extend our understanding of the initiation of deep convection in the tropics. Gaining insights into the key factors governing the development of deep clouds in the tropics will help guide modelers working on improving or developing new convective parameterizations. In turn, these will enhance the representation of clouds and precipitation in climate models and ultimately help reduce some uncertainties associated with climate change predictions.
TITLE: Quantifying the Environmental Controls on Convective Initiation in the Tropics using the WRF-ARW Model
ABSTRACT: Understanding and modeling atmospheric convection remains challenging because convective clouds form and organize at a wide range of spatial and temporal scales. Convection starts with shallow clouds that grow and aggregate over a couple of hours into congestus, which finally become deep convective clouds. This process depends on complex interactions between the surface, the boundary layer, the thermodynamics, and the circulation. Moreover, long-term, high-resolution observations are scarce, particularly in the tropics, hindering our understanding of the shallow to deep (STD) convective transition. This explains, in part, why climate models still fail to represent the diurnal cycle of precipitation. One way to better understand the physical mechanisms responsible for developing and organizing convection is to use cloud-resolving models, which can represent the scale of clouds and turbulent eddies.
In this study, we will perform high-resolution simulations of the STD transition to investigate its controlling mechanisms. The simulations will be carried over tropical regions such as the Amazon rainforest, the Congo rainforest, and the Pacific Ocean, and the results will be contrasted. We will use the Advanced Research WRF (WRF-ARW) regional model with a spatial resolution of about a few hundred meters to capture all scale's convective initiation. We will then impose perturbations in the atmospheric fields and observe the changes in the evolution of the cloud field, i.e., evaluate how each triggering mechanism affects the STD transition. We expect that this sensitivity analysis will help to extend our understanding of the initiation of deep convection in the tropics. Gaining insights into the key factors governing the development of deep clouds in the tropics will help guide modelers working on improving or developing new convective parameterizations. In turn, these will enhance the representation of clouds and precipitation in climate models and ultimately help reduce some uncertainties associated with climate change predictions.
