Investigation of Cloud Variability, Hydrological and Carbon Cycle in the Atmosphere in Response to Global Warming
Kao, Angela 1989-
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The goal of this research is to increase the understanding of changes in the hydrological and carbon cycles in response to global warming. Global oceanic recycling rate, along with meteorological variables are analyzed using the thirteen Coupled Models Inter-comparison Project (CMIP5) data from 1988 to 2008. On a worldwide scale, there has been a long-term decreasing trend of the global average oceanic recycling rate. On a regional scale, there are positive trends of the recycling rate over the Intertropical Convergence Zone (ITCZ) and negative trends over the sub-tropical dry areas. To better understand the hydrological cycle over the wet and dry areas, we examined the precipitation, vertical velocity, cloud, and water vapor contents from CMIP5 models. All meteorological variables associated with precipitation demonstrate favorable conditions for increasing precipitation over the wet areas and decreasing precipitation over the dry areas. The consistent trends in these variables, such as vertical velocity, cloud, and liquid and ice water contents, as provided by the CMIP5 models, yield a clearer picture of the dynamics and physics behind the temporal variation of precipitation over different areas. Atmospheric Infrared Sounder (AIRS) CO2 data is used to study the impact of drought on mid-tropospheric CO2 concentrations. For the first time, it is found that the mid-tropospheric CO2 concentration is approximately one part per million by volume higher during the dry years than the wet years over the southwest USA. During drought conditions, there is increased rising air over most of the regions, which can bring high surface CO2 concentrations into the mid-troposphere. In addition to the circulation, there is added CO2 emitted from the biosphere during times of drought, which can contribute to higher concentrations of CO2 in the atmosphere. A multiple-regression method is applied to explore the relationship between Pacific North American pattern (PNA) and CO2 concentrations. During the positive phase of PNA, there are positive CO2 anomalies over the northwestern part of North America, which are related to increased CO2 emissions from bacteria in the soil and greater CO2 being released from melting permafrost.