Abstract The Summer Arctic Oscillation (SAO) has received little attention compared with the Winter Arctic Oscillation (WAO). However, recent studies have reported that the SAO is associated with extreme heat events in the Northern Hemisphere. Using reanalysis and satellite datasets, this study investigates the spatial pattern and dynamical mechanisms of the SAO. While the WAO represents the meridional displacement of the eddy-driven jet at ∼40°N, the SAO shows zonal wind anomalies, one in the subtropics (∼30°N) and the other along the Arctic coast (∼75°N). The center of action in the subtropics is mainly driven by meridional wave propagation, while that near the Arctic is largely dominated by baroclinic eddy generation at the surface. The findings here suggest that Arctic cloud cover plays an important role in the SAO, which increases the low-level meridional temperature gradient through the shortwave cloud radiative effect during the positive SAO phase. Arctic sea ice anomalies show a positive correlation with the SAO across most of the Arctic Ocean, partly offsetting the cloud radiative effect. The SAO index shows a strong positive correlation with the cloud cover in the Arctic and upper-level zonal wind along the Arctic coast, showing a clear double jet structure in the Northern Hemisphere at the positive SAO phase. This study suggests a new perspective on annular mode dynamics in Northern Hemisphere summer and the need for more studies on the summer jet dynamics distinct from winter.

Abstract This study examines how the summertime Indian Ocean (IO) SST anomalies (SSTAs) affect the Indian summer monsoon (ISM) and its predictability in the El Niño developing years from the perspective of seasonal predictions. The CFSv2-COLA ensemble seasonal reforecasts successfully predicted the ISM in 1972 but failed in 1997, as those years exhibited drastically different ISM states. Our sensitivity experiments, in which the ocean and atmosphere are decoupled in the tropical IO with the prescribed SST, reveal that the erroneous prediction of cold IO SSTAs in 1997 exacerbates an El Niño–induced ISM drought and “correcting” these SST errors improves the ISM prediction substantially, whereas a good prediction of the summertime IO SSTAs contributes positively to the skillful ISM reforecast in 1972. It is also demonstrated that the warm IO SSTAs centered in the Arabian Sea in 1997 reduce sea level pressures locally and steer the low-level anomalous winds to transport water vapor into India. This regional process counters the El Niño–induced drought tendency and results in a nearly normal ISM that defies the historical El Niño–ISM relation. However, the warm SSTAs centered at the western equatorial IO in 1972 strengthen the anomalous Walker circulations originally set up by the developing El Niño in the Indo-Pacific domain, which further enhance the El Niño evolution and its teleconnection to the ISM. This interbasin feedback process intensifies the typical El Niño–ISM relation. The spatial structure of the summer IO SSTAs may determine whether the IO regional process or the interbasin process prevails. The year 2015 is also discussed as another relevant case.

Background: In the Kingdom of Saudi Arabia, various COVID-19 vaccines were administered during the pandemic. However, region-specific real-word comparative data on their immunogenicity remain limited. This study aimed to assess the serological responses to Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and AstraZeneca (ChAdOx1 nCoV-19) vaccines in a diverse population living in KSA. Methods: This observational study included 236 adults recruited from vaccination sites in Riyadh. Participants provided serum samples at predefined intervals: before the first dose, after the first dose, after the second dose, and post-vaccination infection (if applicable). IgG and neutralising antibodies were quantified using ELISA assays. Demographic and vaccination data, and their associations with antibody responses, were evaluated. Results: At baseline, 75.4% of participants were positive for SARS-CoV-2 IgG, suggesting high prior exposure. Marked incremental increases in IgG levels were observed after each vaccine dose. Both Moderna and Pfizer elicited stronger responses, with Pfizer inducing the strongest early response and Moderna achieving the highest overall titres. Among IgG-positive individuals, neutralising antibodies were detected in 98.1%. There were no statistically significant differences by age or gender, although males tended to show higher mean titres. Heterologous vaccine schedules induced comparable or enhanced immunogenicity relative to homologous schedules, supporting their use in flexible immunisation strategies. Conclusions: All COVID-19 vaccines administered in Saudi Arabia elicited robust antibody responses, particularly the mRNA-based vaccines. Our findings support their continued use and justify varied vaccination approaches, including mix-and-match booster strategies, to enhance community immunity.

GIM/FP/GP: [Formula: see text] Public Health: [Formula: see text].

To avert criticism and losses of trust, robots that adopt social roles in the near future will have to be aware of and follow the norms of the communities in which they operate. However, norms often conflict with one another, and resolving such conflicts requires prioritizing one norm and violating the other, conflicting norm. As a result, robots will face moral disapproval from at least some of their human interaction partners. We investigate a powerful tool that humans use—and autonomous agents should use—to manage such moral disapproval and maintain trust: justifications, which explain not just why the agent acted but what norms and values the action upheld. In three experiments (N = 3,596), we demonstrate, replicate, and generalize that justifications, more than mere explanations, mitigate moral disapproval and recover robots’ perceived trustworthiness, even when the robot’s action is in direct moral disagreement with the human observer. We conclude that people simultaneously blame the robot for its specific norm-violating action and appreciate the robot’s integrity to make trustworthy decisions. Justifying norm-violating actions may allow robots to become better integrated into human communities and adopt social roles that will involve morally significant decisions.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-17983-2.