Details:

Journal Title:
Journal of Climate
Personal Author:
Pan, B. ; Hsu, K. ; AghaKouchak, A. ; Sorooshian, S. ; Higgins, W.
Pan, B. ; Hsu, K. ; AghaKouchak, A. ; Sorooshian, S. ; Higgins, W. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office)
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office) Less -
Description:
Precipitation variability significantly influences the heavily populated West Coast of the United States, raising the need for reliable predictions. We investigate the region’s short- to extended-range precipitation prediction skill using the hindcast database of the Subseasonal-to-Seasonal Prediction Project (S2S). The prediction skill–lead time relationship is evaluated, using both deterministic and probabilistic skill scores. Results show that the S2S models display advantageous deterministic skill at week 1. For week 2, prediction is useful for the best-performing model, with a Pearson correlation coefficient larger than 0.6. Beyond week 2, predictions generally provide little useful deterministic skill. Sources of extended-range predictability are investigated, focusing on El Niño–Southern Oscillation (ENSO) and the Madden–Julian oscillation (MJO). We found that periods of heavy precipitation associated with ENSO are more predictable at the extended range period. During El Niño years, Southern California tends to receive more precipitation in late winter, and most models show better extended-range prediction skill. On the contrary, during La Niña years Oregon tends to receive more precipitation in winter, with most models showing better extended-range skill. We believe the excessive precipitation and improved extended-range prediction skill are caused by the meridional shift of baroclinic systems as modulated by ENSO. Through examining precipitation anomalies conditioned on the MJO, we verified that active MJO events systematically modulate the area’s precipitation distribution. Our results show that most models do not represent the MJO or its associated teleconnections, especially at phases 3–4. However, some models exhibit enhanced extended-range prediction skills under active MJO conditions.
Keywords:
[+]
Forecasting La Nina Madden-Julian Oscillation
Source:
Journal of Climate, 32(1), 161-182
DOI:
https://doi.org/10.1175/jcli-d-18-0355.1
Document Type:
Journal Article
Funding:
Grant no. NA14OAR4310222
Rights Information:
Other
Compliance:
CHORUS
Main Document Checksum:
[+]
urn:sha256:f86d52cd33daf60f33ecccfd52e3ccd18cd34f359d100c83fdc92c205e0f07e4
Download URL:
https://repository.library.noaa.gov/view/noaa/48399/noaa_48399_DS1.pdf
File Type:

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