The Kuroshio front to the east of Taiwan: seasonal feature, variability and mechanism

Oceanic front, especially Kuroshio front, is an important phenomenon that is of great significance for scientific research, national economy and military uses. However, Kuroshio front to the east of Taiwan （KFETW in brief） was rare investigated. In this study, reanalysis method is used to study the KFETW＇s temporal and spatial variability and frontogenesis mechanism. It is found that although surface thermal front to the east of Taiwan is not obvious, there is an all-year strong Kuroshio thermal front called KFETW under the surface. The KFETW is connected to the south section of Kuroshio front in the East China Sea （KFECS in brief） and distributes along the east coastline of Taiwan. The KFETW has multi-scale variation feature. It has significant seasonal signal, and its intensity and width reach their maximum in summer. By using the reanalysis results obtained from this study, frontogenesis and changing mechanisms of the KFETW are discussed. It is found that both the Kuroshio and up-welling to the east of Taiwan can affect this front, and the up-welling may be the predominant factor in KFETW＇s frontogenesis and maintenance mechanism.

Interannual variations in length of day and atmospheric angular momentum, and their seasonal associations with El Ni^o/Southern Oscillation-like sea surface temperature patterns

This study examines the seasonal connections between the interannual variations in LOD （length of day）/ AAMglobe （the relative atmospheric angular momentum for the whole globe） and the ENSO-like SST （El Nifio/ Southern Oscillation-like sea surface temperature） pattern and corresponding zonal and vertical circulations. Consistent with previous studies, the ENSO-like SST impact the following season LOD/AAMglobe, with the strongest correlations in DJF （December, January, and February）, when it is likely to be the peak E1 Nino/La Nifia period. Lag correlations between the interannual variations in LOD/AAMglobe and surface temperature, and the interannual variations in LOD and both zonal circulation and vertical airflow around the equator, consistently indicate that the LOD/AAMglobe reflect the potential impacts of variations in the Earth＇s rotation rate on the following season＇s sea surface temperatures （SST） over the tropical central and eastern pattern is located）. Pacific （where the ENSO-like SST Moreover, the centers of strongest variation in the AAMcolumn （the relative atmospheric angular momentum for an air column and the unit mass over a square meter） are located over the mid-latitudinal North Pacific in DJF and MAM （March, April, and May）, and over the mid-latitudinal South Pacific in JJA （June, July, and August） and SON （September, October, and November）. This suggests that the AAMcolumn over the mid-latitudinal Pacific around 30°N （30~S） dominate the modulation of Earth＇s rotation rate, and then impact the variations in LOD during DJF and MAM （JJA and SON）.