Stephen W. Bieda IIIATMO 529: OBJ ANALY/ATMO+REL SCI

5 December 2007

The Combined Pacific Variability Mode (henceforth CPVM) has a known relationship with NAMS variability at onset. (referenced in Castro et al. 2007, J. Climate)

Further research by Bieda et al. 2007 suggests that the CPVM has a known relationship with transient inverted troughs during the North American Monsoon Season (NAMS). Negative (positive) CPVM provides more (less) of these transient features during the season, with more (less) precipitation falling over a northward (southward) deviated track.

A predictive seasonal parameter for the NAMS still has yet to be found.

Source: NAME Science Plan 2004

CPVM – Combined Pacific Variability Mode: uses the two (2) rotated EOFs of global SSTs which are associated with interannual and interdecadal variability in the tropical Pacific Ocean. (referenced in Castro et al. 2007, J. Climate)

Source: Castro et al. (2007)

CPVM Positive – CPVM Negative Years showing the basic principle

of onset relationship.

Time Frame: All year for ocean, JJA for Precipitation

Years covered: 1979 - 2006 Datasets Used:

International Comprehensive Ocean-Atmosphere Data Set (1979-2007): 1°x1° dataset of monthly Ocean SSTs

North American Regional Reanalysis (1979- 2006): 0.3°x0.3° dataset of monthly precipitation

Region covered: NARR - boundaries were 10N – 42N, 122W –

90W (NAME Tier II).

Convert the summer precipitation totals to SPI over the Tier II domain.

Perform the REOF analysis of global SSTs by the methods of Castro et al. (2007a,b).

Lag the dominant modes of SSTs (i.e. JFM, FMA, etc.), to perform a “hindcast” of an averaged monsoon season.

I’m not convinced that I personally calculated the CPVM correctly, due to the results that were generated.

The reason is that the correlation should be increasing over the area as we approach the NAM season, rather than remaining steady.

Work will continue to correct the mistakes made, and generate composites that will hopefully be more convincing.

Castro, C.L. R.A. Pielke Sr., J.O. Adegoke, 2007: Investigation of the Summer Climate of the Contiguous U.S. and Mexico Using the Regional Atmospheric Modeling System (RAMS). Part A: Model Climatology (1950-2002). J. Clim., 20, 3844-3865.  

Castro, C.L., R.A. Pielke Sr., J.O. Adegoke, S.D. Schubert, P.J. Pegion, 2007: Investigation of the Summer Climate of the Contiguous U.S. and Mexico Using the Regional Atmospheric Modeling System (RAMS). Part B: Model Climate Variability. J. Clim., 20, 3866-3887.

Mesinger, F., G. DiMego, E. Kalnay, K. Mitchell, P.C. Shafran, W. Ebisuzaki, D. Jovic, J. Woollen, E. Rogers, E.H. Berbery, M.B. Ek, Y. Fan, R. Grumbine, W. Higgins, H. Li, Y. Lin G. Manikin, D. Parrish, W. Shi, 2006: North American Regional Reanalysis. Bull. AMS, 87, 343-360.

North American Monsoon Experiment: Science and Implementation Plan 2004: NAME Science Working Group [Available on line at http://www.cpc.ncep.noaa.gov/products/precip/monsoon/NAME.html].

Worley, S.J., S.D. Woodruff, R.W. Reynolds, S.J. Lubker, and N. Lott, 2005: ICOADS Release 2.1 data and products. Int. J. Climatol. (CLIMAR-II Special Issue), 25, 823-842 (DOI: 10.1002/joc.1166).

Thank you for your time.