The El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are high degree synergic air–sea interactions greatly affecting the interannual variability of rainfall in China. This study reveals the possible cooperative impacts of the ENSO and IOD on boreal autumn rainfall anomalies in China, on the basis of data analysis collected during 1951–2010. Our results suggest that the positive phase of the combined ENSO and IOD events may result in an anomalous lower-level anticyclone over the western North Pacific (WNP) region, with a southward shift of the strengthened East Asian jet stream (EAJS). An enhanced moisture supply is transported to increase autumn rainfall over southern China by the southwesterly winds. In the negative phase, however, southerly anomalies are observed between the anomalous cyclone and anticyclone over the Indo-China Peninsula and the WNP, which carry more moisture to the Loess Plateau (LP) area with a northward shift of the weakened EAJS, leading to an increase of autumn rainfall in this area. Note that the negative IOD plays an important role in the cooperative influences on the autumn rainfall anomalies over the LP in that the associated anomalous lower-level cyclone shifts westward compared to the impacts of the pure La Niña. The regional asymmetric responses of autumn rainfall to the positive and negative phases of the ENSO and IOD could be attributed to the different responses of lower-level circulation over WNP and the meridional shift of the upper-level EAJS. Results demonstrate that the combined ENSO and IOD induce an anomalous zonal gradient of sea surface temperature (SST) over the tropical Indo-Pacific Ocean to alter the convection anomalies over the Indo-Pacific warm pool that further affect the upper and lower atmospheric circulations by means of a Rossby wave response.

This study investigates variations of sea surface temperature (SST) anomalies in the South China Sea (SCS) during developing autumn of various El Niño events. The warm SST anomalies are observed in the SCS for canonical El Niño and El Niño Modoki I, whereas the cold SST anomalies are found for El Niño Modoki II. The ocean heat budget analyses show that the latent heat flux change induced by various types of El Niño events is a major contributor to the SCS SST variations. An anomalous anticyclone resides near the Philippine Sea for canonical El Niño and El Niño Modoki I, which induces the southerly wind anomalies over the SCS and thus weakens the climatological northeasterly in boreal autumn. The weakened surface wind speed reduces heat loss from the ocean, leading to a warmer state in the SCS. However, for El Niño Modoki II, the anomalous anticyclone shifts westward to the west of the SCS, and thus the northeasterly wind anomalies appear in the SCS. The northeasterly anomalies enhance the climatological northeasterly monsoon, increase the wind speed, and increase heat loss from the ocean, thus resulting in a cooling in the SCS. The anomalous anticyclone associated with El Niño events also increases shortwave radiation. The increases of the shortwave radiation can also contribute to the SCS warming for canonical El Niño and El Niño Modoki I in addition to the warm effect from the latent heat flux. Because the cooling effect from the latent heat flux is larger than that of the shortwave radiation for El Niño Modoki II, the SCS for El Niño Modoki II tends to be cool.

The authors use a statistical regional climate model [Statistical Regional Model (STAR)] to project the Tibetan Plateau (TP) climate for the period 2015–50. Reanalysis datasets covering 1958–2001 are used as a substitute of observations and resampled by STAR to optimally fit prescribed linear temperature trends derived from the Max Planck Institute Earth System Model (MPI-ESM) simulations for phase 5 of the Coupled Model Intercomparison Project (CMIP5) under the representative concentration pathway 2.6 (RCP2.6) and RCP4.5 scenarios. To assess the related uncertainty, temperature trends from carefully selected best/worst ensemble members are considered. In addition, an extra projection is forced by observed temperature trends in 1958–2001. The following results are obtained: (i) Spatial average temperature will increase by 0.6°–0.9°C; the increase exceeds 1°C in all months except in boreal summer, thus indicating a reduced annual cycle; and daily minimum temperature rises faster than daily maximum temperature, resulting in a narrowing of the diurnal range of near-surface temperature. (ii) Precipitation increase mainly occurs in early summer and autumn possibly because of an earlier onset and later withdrawal of the Asian summer monsoon. (iii) Both frost and ice days decrease by 1–2 days in spring, early summer, and autumn, and the decrease of frost days on the annual course is inversely related to the precipitation increase. (iv) Degree-days increase all over the TP with peak amplitude in the Qaidam Basin and the southern TP periphery, which will result in distinct melting of the local seasonal frozen ground, and the annual temperature range will decrease with stronger amplitude in south TP.

The Mid‐to‐Lower Reaches of the Yangtze River (MLRYR) suffered an extreme drought in the post‐monsoon season of 2019, contemporaneous with a strong Central Pacific (CP) El Niño and a super positive Indian Ocean Dipole (pIOD) event. The present work shows that CP El Niño‐related Pacific Sea Surface Temperature Anomalies (SSTAs) weakened the western North Pacific anticyclone to prevent moisture transport to the MLRYR and explained 60% of the drought intensity. The super pIOD with an extremely cold SSTA in the tropical Southeastern Indian Ocean contributed 40% of the drought amplitude via an atmospheric teleconnection. The Indian Ocean cold SSTAs first strengthened the post‐monsoon rainfall and enhanced diabatic heating over South Asia, leading to baroclinic circulation anomalies with induced descending motion over the MLRYR. The aggravated dry conditions there ultimately broke the historical drought record for the period since 1979.

The mean circulation pattern and its mechanism over Caiwei Guyot (1,308–5,600 m) in the Northwest Pacific were studied utilizing 3 years of in situ data. A deep anticyclonic cap was found to enclose the entire guyot from its bottom up to a depth of 728 m, which is composed of a stable but highly asymmetric anticyclonic circulation at the foot and a bottom‐trapped anticyclonic circulation over the summit. On the slope, the circulation is complex with a dominant anticyclonic circulation near the bottom and a weak cyclonic circulation at ∼2,200 m. The anticyclonic cap intensity over the summit is significantly modulated by the time‐varying impinging flow. An intensified cold ring above the summit edge was observed at Caiwei Guyot, which differs from the cold domes observed over traditional conic seamounts. Further analysis suggests that the impinging flow is primarily responsible for the cap formation, and the M₂ tide‐seamount interaction plays a secondary role. The anticyclonic cap may play a role in the local geological distribution.

The vertical propagation of middepth (200–1,500 m) zonal velocity in the equatorial Indian Ocean (EIO) and its relationship with surface wind forcing are investigated. We focus on semiannual time scales, using in situ mooring observations and an oceanic reanalysis product that can reasonably well reproduce the structure and magnitude of the observed middepth zonal velocity in the EIO. The pronounced semiannual cycle in observed middepth zonal currents indicates a clear upward phase propagation with particularly robust signatures at depths of 500–1,000 m between 3°S to 3°N, 70 to 85°E. The main characteristics of the middepth currents are consistent with vertically propagating first‐meridional‐mode Rossby wave at semiannual period. Theory suggests that equatorial Kelvin waves, forced by zonal wind variations in the western half of the basin, transfer energy downward and eastward, reflecting into Rossby waves at the eastern boundary. These reflected Rossby waves transfer energy downward and westward, contributing greatly to observed phase propagation at middepths in the EIO.