Open AccessFormation and Maintenance Mechanisms of the Subseasonal Eastern Pacific Pattern: Energetics Analysis
Author(s) -
Wang Miao,
Tan Benkui
Publication year - 2021
Publication title -
earth and space science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.843
H-Index - 23
ISSN - 2333-5084
DOI - 10.1029/2021ea001851
Subject(s) - baroclinity , eddy , sink (geography) , barotropic fluid , kinetic energy , energetics , geopotential height , climatology , geopotential , mixed layer , atmospheric sciences , physics , environmental science , geology , meteorology , precipitation , thermodynamics , geography , cartography , quantum mechanics , turbulence
Based on daily data from Japanese 55‐year Reanalysis (JRA‐55), this study examines the formation and maintenance mechanisms of the subseasonal eastern Pacific (EP) pattern from an energetics perspective. Results show that the baroclinic energy conversion (CP B ) acts as an important energy source to overcome the thermal damping caused by the transient eddies and as a major kinetic energy (KE) source. The feedback forcing of transient eddies (CK E ) acts as a major KE source during the growing stage and a major KE sink during the decay of the EP pattern. At the same time, the barotropic energy conversion (CK B ) also makes substantial positive KE contribution. The results also suggest that the EP dynamics differ among different tropospheric layers. In the upper layer, CP B , CK B , and the anomalous geopotential height flux divergence (AGHFD) term all act as major KE source, while CK E acts as a major KE source (sink) during the growth (decay) stage of the EP pattern. The middle layer is mainly driven by CP B and AGHFD: CP B acts as a KE source while AGHFD as a sink. In the lower layer, CP B and AGHFD act as major KE sources with the later larger than the former, while the friction term damps the EP pattern heavily. It is found that the vertical component of the divergence of geopotential height flux anomaly plays a crucial role in the dynamic coupling of the different vertical parts of the EP pattern.