Characteristics and mechanisms of the intraseasonal variability of sea surface salinity in the southeastern Arabian Sea during 2015-2020

Based on Soil Moisture Active Passive sea surface salinity(SSS)data from April 2015 to August 2020,combined with Objectively Analyzed Air-Sea Heat Flux and other observational data and Hybrid Coordinate Ocean Model(HYCOM)data,this work explores the characteristics and mechanisms of the intraseasonal variability of SSS in the southeastern Arabian Sea(SEAS).The results show that the intraseasonal variability of SSS in the SEAS is very significant,especially the strongest intraseasonal signal in SSS,which is located along the northeast monsoon current(NMC)path south of the Indian Peninsula.There are remarkable seasonal differences in intraseasonal SSS variability,which is very weak in spring and summer and much stronger in autumn and winter.This strong intraseasonal variability in autumn and winter is closely related to the Madden-Julian Oscillation(MJO)event during this period.The northeast wind anomaly in the Bay of Bengal(BOB)associated with the active MJO phase strengthens the East India Coastal Current and NMC and consequently induces more BOB low-salinity water to enter the SEAS,causing strong SSS fluctuations.In addition,MJO-related precipitation further amplifies the intraseasonal variability of SSS in SEAS.Based on budget analysis of the mixed layer salinity using HYCOM data,it is shown that horizontal salinity advection(especially zonal advection)dominates the intraseasonal variability of mixed layer salinity and that surface freshwater flux has a secondary role.

Evaluation of reanalysis surface wind products with quality-assured buoy wind measurements along the north coast of the South China Sea

Three archived reanalysis wind vectors at 10 m height in the wind speed range of 2-15 m/s,namely,the second version of the National Centres for Environmental Prediction(NCEP)Climate Forecast System Reanalysis(CFSv2),European Centre for Medium-Range Weather Forecasting Interim Reanalysis(ERA-I)and NCEPDepartment of Energy(DOE)Reanalysis 2(NCEP-2)products,are evaluated by a comparison with the winds measured by moored buoys in coastal regions of the South China Sea(SCS).The buoy data are first quality controlled by extensive techniques that help eliminate degraded measurements.The evaluation results reveal that the CFSv2 wind vectors are most consistent with the buoy winds(with average biases of 0.01 m/s and 1.76°).The ERA-I winds significantly underestimate the buoy wind speed(with an average bias of-1.57 m/s),while the statistical errors in the NCEP-2 wind direction have the largest magnitude.The diagnosis of the reanalysis wind errors shows the residuals of all three reanalysis wind speeds(reanalysis-buoy)decrease with increasing buoy wind speed,suggesting a narrower wind speed range than that of the observations.Moreover,wind direction errors are examined to depend on the magnitude of the wind speed and the wind speed biases.In general,the evaluation of three reanalysis wind products demonstrates that CFSv2 wind vectors are the closest to the winds along the north coast of the SCS and are sufficiently accurate to be used in numerical models.

Single-Cell Mapping of Brain Myeloid Cell Subsets Reveals Key Transcriptomic Changes Favoring Neuroplasticity after Ischemic Stroke

Interactions between brain-resident and periph-eral infiltrated immune cells are thought to contribute to neuroplasticity after cerebral ischemia.However,con-ventional bulk sequencing makes it challenging to depict this complex immune network.Using single-cell RNA sequencing,we mapped compositional and transcriptional features of peri-infarct immune cells.Microglia were the predominant cell type in the peri-infarct region,displaying a more diverse activation pattern than the typical pro-and anti-inflammatory state,with axon tract-associated micro-glia(ATMs)being associated with neuronal regeneration.Trajectory inference suggested that infiltrated monocyte-derived macrophages(MDMs)exhibited a gradual fate trajectory transition to activated MDMs.Inter-cellular crosstalk between MDMs and microglia orchestrated anti-inflammatory and repair-promoting microglia phenotypes and promoted post-stroke neurogenesis,with SOX2 and related Akt/CREB signaling as the underlying mechanisms.This description of the brain's immune landscape and its relationship with neurogenesis provides new insight into promoting neural repair by regulating neuroinflammatory responses.