Modeling Investigation of Atmospheric Moisture Transport over the North Pacific: Role of Pacific Decadal Oscillation
Abstract
Increasing atmospheric temperatures cause changes in the hydrological cycle by giving the atmosphere a greater moisture-holding capacity. Along with the greenhouse-gas-emissions forced long-term trends, the atmospheric temperature and water content over the North Pacific can also fluctuate under the driving force by the Pacific Decadal Oscillation (PDO). In order to better understand the role which the PDO plays in the North Pacific water budgets and pathways, we employed the NCAR Community Atmosphere Model 5.0 (CAM) and conducted sensitivity experiments to examine how atmospheric moisture transport responds to sea surface temperature (SST) anomalies associated with the PDO phase transitions. We have found that changes in the storm tracks over the North Pacific due to changes in the sea surface temperatures increase or decrease the amount of moisture transport into Alaska and Hawaii. The moisture transport into Hawaii is consistently lower in the warm phase of the PDO compared to the cool phase. The moisture transport into Alaska has a seasonal dependence and increases during the winter but decreases during the spring, summer, and fall as the PDO phase changes. These differences in moisture transport are reflected in the local precipitation rates. During the warm phase, the distribution of precipitation rates typically has a higher peak and a more narrow distribution than in the cool phase. This study has important implications for improving understanding of precipitation events.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMGC41A0955B
- Keywords:
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- 1616 GLOBAL CHANGE / Climate variability;
- 1655 GLOBAL CHANGE / Water cycles;
- 3305 ATMOSPHERIC PROCESSES / Climate change and variability