Julie Caron

Associate Scientist
TIIMES - CGD
WCAS

Contact Information:
PO Box 3000, Boulder, CO 80307-3000
Office: ML - 320d
Telephone: 303-497-1347
Email: jcaron@ucar.edu
Home Page

Project Summary:

Click on picture to view the entire figure.

T85 vanom average vertical low level jet (LLJ)

I’ve continued to analyze the structure of the diurnal cycle of the simulated low-level jet (LLJ) in CAM at multiple resolutions compared with previous studies & with the North American Regional Reanalysis (NARR).  I presented some of the results in a talk at the Water Cycle Retreat at the end of last year.

In terms of the diurnal cycle, CAM does a good job of capturing the structure of the LLJ even at T42. The low-level wind structure, and the vertical structure of the zonal and meridional wind over the central United States match previous studies quite well. I will be submitting a manuscript for publication which includes the horizontal and vertical structure of the jet as well as a summary of the associated moisture transports.

The Nested Regional Climate Model (NRCM) is an important tool to address upscaling and downscaling issues. Analysis of NRCM tropical channel runs is relevant to our understanding of water cycle processes in the tropics, since it represents an important step in the direction of improving the treatment of water cycle processes in a model from near cloud-resolving to climate scales.

I have incorporated changes to a comprehensive diagnostic package to include the NRCM model data.   These diagnostics allow a comparison of the model’s climate, and some modes of variability, with observational data as well as with CAM.

I’ve also evaluated the MJO in the NRCM as well as in the full CAM and a channel version of CAM at T170 resolution. The channel version of CAM is an imitation of the NRCM framework in global CAM, where the results are nudged back to NCEP observations outside the tropical channel.

The MJO is linked to the water cycle through convection. The consistency of the MJO’s wet and dry phases are an important characteristic of the tropical climate particularly for southwest Asia and the eastern Indian Ocean where the signal is the strongest. Although the magnitude of the MJO is too weak compared with observations in the NRCM, T170 CAM, and T170 Channel CAM, there is some evidence so far, that the magnitude of the MJO is improved in the channel version of CAM compared with standard CAM, which implies that the channel framework used in the NRCM impacts the magnitude of tropical variability such as the MJO.

Presentations:

• The Low-Level Jet and Associated Moisture Transports in CAM, Boulder USA, Decmeber 2006

Publications:

Hurrell, J. W., J. J. Hack, D. Shea, J. M. Caron, J. Rosinski, 2007: A new sea surface temperature and sea ice boundary data set for the Community Atmosphere Model. J. Climate, 19, 5100-5122.