Research
What I do
What I do
The Land-Atmosphere-Ocean Interactions (LAOI) Group at The University of Arizona's Hydrology and Atmospheric Sciences Department researches the interfacial and boundary layer processes at the Earth's surface and their effects on global climate. The group also works to improve the characterization of these processes in climate and numerical weather prediction models by analyzing the model parameterizations of these processes using field data and remotely sensed data or by integrating such data into the models. I specialize in the interfacial processes between the ocean and the atmosphere and between sea ice and the atmosphere as well as the processes that occur in the marine atmospheric boundary layer (MABL).
I have strongly worked with the National Center for Atmospheric Research's Community Earth System Model (CESM). I am currently working on the development of the Department of Energy's Energy Exascale Earth System Model (E3SM) and have also worked on the Regional Arctic System Model (RASM). I have also worked with the scientific community in the SeaFlux project analyzing and improving satellite-derived ocean surface turbulent flux products by providing algorithm and product intercomparisons. I have also contributed to VOCALS with our project involving an analysis of cloud properties in the southeastern Pacific stratus deck and its evaluation in the atmospheric component of the CCSM (predecessor to CESM).
Surface turbulent fluxes of momentum, heat, and moisture at the interface between the atmosphere and ocean represent an en exchange of energy between the two. In models used to simulate climate and weather, these fluxes have to be parameterized because they occur at scales much smaller than the typical grid size of these models. Much of my early work dealt with evaluating which of these parameterizations produce more accurate estimates of air-sea fluxes. Click here to learn more about this research here.
I also evaluated how the exchange of heat, moisture, and momentum are represented in global climate models at the atmosphere-sea ice interface. Learn about this project here.
The atmospheric boundary layer is the lowest layer of the atmosphere that is in direct contact with the surface of the Earth. In other words, this is the layer that is directly impacted by the surface. The depth of this layer is a very important quantity to know accurately. We undertook a climatology of the height of the top of the marine boundary layer from soundings made by weather balloon launches from experimental cruises undertaken in the eastern tropical Pacific. Learn about this work here.
Sea surface temperature (SST) is an important bottom boundary condition for atmospheric models. Typically, SST is taken to be at ~10 meters below the surface. However, the temperature at the very surface can be much different than that at 10 meters below depending on the time of day. Prof. Xubin Zeng developed a scheme to adjust model SST to skin temperature, and I implemented it into a global climate model. Learn more about this work here.
Clouds are quite common in the marine boundary layer globally. The focus of some of my recent work has been on this topic, focusing on stratus/stratocumulus decks off of the subtropical west coasts of the continents. A prime example of such a deck is the one off of the Southern California coast that brings the marine layer clouds inwards overnight. Such clouds have long been poorly represented in global climate models. Look here about how I have contributed to the rectification of this problem.
Specific humidity, the ratio of the mass of water vapor to the total mass of air, like temperature normally decreases with height away from the surface. However, there are instances when there are layers in which specific humidity increases with height. These have been coined humidity inversions similar to the layers in which temperature increases with height. I undertook a study to establish a global climatology of such humidity inversions. You can learn about the results of this climatology here.
The land surface is a more complicated interface than the ocean because of its inhomogeneous nature. The water within the soil can evaporate. Rain intercepted by vegetation can also evaporate, and the plants themselves exchange water into the air in order to photosynthesize. Then, there are bodies of water. Another complication for the storage of water underground is the depth-to-bedrock. The depth-to-bedrock is shallower in higher terrain and much deeper at valley bottoms that collect the sediment eroded from the mountains. I have used a global estimate of depth-to-bedrock to represent variable soil thickness in two global climate models. Learn about how I did this here.