Evidence of Specific MJO Phase Occurrence with Summertime California Central Valley Extreme Hot Weather

• DOI: 10.1007/s00376-019-8167-1
• Publication Date: 2019-04-12T09:03:33Z
• Authors: Yun-Young Lee; Richard Grotjahn
• Keywords: Madden–Julian oscillation; Outgoing longwave radiation; Teleconnection

This study examines associations between California Central Valley (CCV) heat waves and the Madden Julian Oscillation (MJO). These have major economic impact. Our prior work showed that CCV are frequently preceded by convection over tropical Indian eastern Pacific oceans, in patterns identifiable with MJO phases. The main analysis method is lagged composites (formed after each phase pair) of synoptic station temperature, outgoing longwave radiation (OLR), velocity potential (VP). Over CCV, positive temperature anomalies occur only Ocean (phases 2–3) or 8–1) (implied OLR VP fields). largest fractions hot days two weeks onset those pairs. significant subsidence convergence above divergence during waves, these structures part larger having areas Oceans. Prior studies can be roughly grouped into clusters: Cluster 2 a wave northwestern North America, while 1 not. composite analyses applied separately to clusters. However, for 2, not significant, large-scale pattern has low correlation field. Therefore, association subsequent more evident than 2.