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Ocean memory is crucial for improving climate models and enhancing the accuracy of climate predictions. Despite its importance, the evolving influence of ocean memory over recent decades on monsoon predictions remains ambiguous. The persistence of sea surface temperature (SST) anomalies, a critical indicator of ocean memory, governs local air-sea coupling processes affecting the Asian-Australian monsoon (A-AM), thereby significantly shaping climate predictions for Asia, Australia, and the broader Indo-Pacific region. Drawing on observational and numerical modeling evidence, the study elucidates that within the context of interdecadal variation in ocean memory, the seasonal persistence of Maritime Continent (MC) SST anomalies was more pronounced during the epoch of robust ocean memory (1982-1999). This persistence sustained the anomalous western North Pacific anticyclone (WNPAC) through an intensified Matsuno-Gill response in the decaying phase of El Niño-Southern Oscillation (ENSO), thereby enhancing its linkage with the A-AM system throughout the monsoon year, contributing to improved prediction skills of the A-AM. In contrast, these air-sea coupling processes have weakened during the weak memory epoch (2000-2017), making it more difficult to capture the characteristics of the A-AM. The decline in MC ocean memory at the onset of the twenty-first century has undermined the prediction skills of the leading modes of the A-AM. Overall, this study underscores the profound influence of ocean memory on monsoon prediction skills while highlighting the significant challenges in addressing A-AM variability and predictability against the backdrop of global warming.

The interannual variability of boreal summer Asian-Australian monsoon (BSAAM) is mainly driven by sea surface temperature anomalies (SSTAs) in the Indian, Pacific, and Atlantic Oceans. Unlike traditional studies that examine the influence of individual oceans on BSAAM subsystems, this study elucidates the distinct and combined impacts of all three oceans on the BSAAM as a unified system. First, we quantify the contributions of the three oceans to the dominant interannual variability of BSAAM using Community Earth System Model (CESM) pacemaker experiments, showing that Pacific, Atlantic, and Indian Oceans contribute approximately 46%, 35%, and 23%, respectively. These quantified contributions capture both the simultaneous influences of the oceans and their effects from preceding seasons. During boreal summer, BSAAM-related SSTAs in the Indian Ocean-Western Pacific (IOWP), the Central-Eastern Pacific (CEP), and the Tropical Atlantic (TA) create a tripole pattern across the tropics. Both the IOWP and CEP directly influence the BSAAM, with the IOWP having a slightly stronger effect. In contrast, the TA’s influence is indirect and relatively weaker, mediated through its interactions with the IOWP and CEP. Differently, from the preceding boreal winter to boreal summer, the TA emerges as the most significant factor, showing progressively strengthening positive SSTAs, similar to the IOWP, while the CEP transitions from an El Niño phase to a La Niña phase. Compared to predictions based on individual oceans, combining the influences of all three oceans extends the BSAAM prediction lead time into the preceding winter and nearly doubles the average precipitation prediction skill in the BSAAM region. These findings provide new insights into forecasting the BSAAM from a comprehensive, multi-ocean perspective.

The Freeze-Thaw process on the Tibetan Plateau (TP) plays a crucial role in local phenology and atmospheric circulation. Utilizing observational and reanalysis data from 1979 to 2018, this study found that the winter TP Freeze-Thaw state (TPFT) explains nearly 20% of the variability in the East Asian summer monsoon (EASM) during Meiyu season (June–July). Results indicate that as the TP trends towards a frozen state, the winter TP soil moisture (TPSM), closely linked to the freeze-thaw process, shows negative anomalies. The negative anomalies can persist into the Meiyu season, causing reduced surface downward longwave radiation and decreased low cloud cover, which in turn result in negative surface air temperature (SAT) anomalies. The negative SAT anomalies act as a link between the TPFT and the EASM, inducing an anomalous anticyclone over the northwest Pacific during the Meiyu season and leading to positive precipitation anomalies in the Yangtze River Basin. Furthermore, the numerical experiments demonstrate that TPFT anomalies play a pivotal role. Finally, hindcast experiment outputs reveal that incorporating winter TPFT as a predictor significantly improves the cross-validated prediction skill, with the model explaining over 54% of the variance in the EASM.

Asthma is a common respiratory disease, and immune system dysregulation has direct relevance to asthma pathogenesis. Probiotics and prebiotics have immunomodulatory effects and can regulate immune responses and may attenuate allergic reactions. Therefore, in this study, we explored the role of probiotics and prebiotics in regulating acute airway inflammation and the TLR4/NF-kB pathway. Allergic asthma model of BALB/c mice was produced and treated with probiotics (LA-5, GG, and BB-12) and prebiotics (FOS and GOS). Then AHR, BALF cells count, EPO activity, IL-4, 5, 13, 17, 25, 33, as well as IFN-γ, total and OVA-specific IgE, IgG1, Cys-LT, LTB4, LTC4, and TSLP levels were measured. Also, the GTP/GOT assay was performed and gene expression of Akt, NLR3, NF-kB, PI3K, MyD88, TLR4, CCL11, CCL24, MUC5a, Eotaxin, IL-38, and IL-8 were determined. Finally, lung histopathological features were evaluated. Treatment with probiotics could control AHR, eosinophil infiltration to the BALF and reduce the levels of immunoglobulins, IL-17, GTP and also decrease mucus secretion, goblet cell hyperplasia, peribronchial and perivascular inflammation and also, EPO activity. It could reduce gene expression of TLR4 and CCL11. On the other hand, IL-38 gene expression was increased by both probiotic and prebiotic treatment. Treatment with probiotics and prebiotics could control levels of IL-4, 5, 13, 25, 33, leukotrienes, the gene expression of AKT, NLR3, NF-κB, MyD88, MUC5a. The prebiotic treatment could control peribronchial inflammation and PI3K gene expression. Both of the treatments had no significant effect on the GOT, TSLP and IL-8, eotaxin and CCL24 gene expression. Probiotics and prebiotics could induce tolerance in allegro-inflammatory reactions and alter immune responses in allergic conditions. Probiotics could also modulate cellular and humoral immune responses and prevent allergic disorders. Main findings of the study Probiotics controls AHR, eosinophil infiltration to the perivascular and BALF, levels of immunoglobulins, IL-17, GTP and also mucus secretion, goblet cell hyperplasia, EPO activity. It could reduce gene expression of TLR4 and CCL11, Probiotics and prebiotics control levels of cytokines (IL-4, 5, 13, 25, and 33), leukotrienes, the gene expression of AKT, NLR3, NF-κB, MyD88, MUC5a, peribronchial inflammation and increase IL-38 gene expression. Prebiotic controls and PI3K gene expression.

The Eurasian continent has experienced significant year-to-year variations of summer heat waves during the past decades. Several possible factors, such as ocean temperature, soil moisture, and changes in land use and greenhouse gases, have been identified in previous studies, but the mechanisms are still unclear. In this study, it is found that the Tibetan Plateau snow cover (TPSC) is closely linked to the interannual variations of summer heat waves over Eurasia. The TPSC variability explains more than 30 % of the total variances of heat wave variability in the southern Europe and northeastern Asia (SENA) region. A set of numerical experiments reveal that the reduced TPSC may induce a distinct teleconnection pattern across the Eurasian continent, with two anomalous high pressure centers in the upper troposphere over the SENA region, which may lead to a reduction of the cloud formation near the surface. The less cloud cover tends to increase the net shortwave radiation and favor a stronger surface sensible heat flux in the dry surface condition over the SENA region, resulting in a deeper, warmer and drier atmospheric boundary layer that would further inhibit the local cloud formation. Such a positive land–atmosphere feedback may dry the surface even further, heat the near-surface atmosphere and thereby intensify the local heat waves. The above dynamical processes also operate on interdecadal time scales. Given the reduction of the TPSC could become more pronounced with increasing levels of greenhouse gases in a warming climate, we infer that the TPSC may play an increasingly important role in shaping the summer heat waves over the SENA region in next decades.

The early summer (May–June) precipitation in Northeast Asia (NEA) accounts for about 25% of the annual total, which is important for the local agriculture production. The potential influencing factors and the related mechanisms of early summer NEA precipitation variability, however, are not fully understood. Our study suggests that a dipolar NEA precipitation anomaly pattern in May–June highly resembles the second leading mode of NEA early summer precipitation variability, can be induced by the winter North Atlantic Oscillation (NAO) through the “capacitor” effect of the Barents sea ice (BSI). Further analysis indicated that during negative NAO winter, anomalous northerlies controlling the Barents Sea tend to increase the local sea ice and reach its peak in spring. The BSI anomalies persist from spring to the following early summer generates the “positive–negative–positive” geopotential height anomalies occupying the Arctic, Kamchatka, and extra-tropical western Pacific. The southerlies on the west flank of the anomalous extra-tropical western Pacific anticyclone advect sufficient water vapor from the Pacific to southern NEA, concurrent with lower-troposphere convergence, leading to rich rainfall over Korea and southern Japan. In contrast, the lower-level divergence may reduce the precipitation over northern NEA. At last, a physical-based empirical model is established using the winter NAO index. It shows that the winter NAO provides a promising predictability source for this anomalous NEA dipolar precipitation pattern.

Predicting surface air temperature (T) is a major task of North American (NA) winter seasonal prediction. It has been recognized that variations of the NA winterT’s can be associated with El Niño–Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). This study presents observed evidence that variability in snow cover over the Tibetan Plateau (TP) and its adjacent areas in prior autumn (September–November) is significantly correlated with the first principal component (PC1) of the NA winterT’s, which features a meridional seesaw pattern over the NA continent. The autumn TP snow cover anomaly can persist into the following winter through a positive feedback between snow cover and the atmosphere. A positive TP snow cover anomalymay induce a negative sea level pressure and geopotential height anomaly over the eastern North Pacific, a positive geopotential height anomaly over Canada, and a negative anomaly over the southeastern United States—a structure very similar to the positive phase of the Pacific–North America (PNA) pattern. This pattern usually favors the occurrence of a warm–north, cold–south winter over the NA continent. When a negative snow cover anomaly occurs, the situation tends to be opposite. Since the autumn TP snow cover shows a weak correlation with ENSO, it provides a new predictability source for NA winterT’s. Based on the above results, an empirical model is constructed to predict PC1 using a combination of autumn TP snow cover and other sea surface temperature anomalies related to ENSO and the NAO. Hindcasts and real forecasts are performed for the 1972–2003 and 2004–09 periods, respectively. Both show a promising prediction skill. As far as PC1 is concerned, the empirical model hindcast performs better than the ensemble mean of four dynamical models from the Canadian Meteorological Centre. Particularly, the real forecast of the empirical model exhibits a better performance in predicting the extreme phases of PC1—that is, the extremely warm winter over Canada in 2009/10—should the model include the autumn TP snow cover impacts. Since all these predictors can be readily monitored in real time, this empirical model provides a realtime forecast tool for NA winter climate.

Compound hot extremes (CHEs) are receiving increasing attention due to their significant impacts on human health, ecosystems, and society compared to individual hot days or nights. While previous studies have focused on the characteristics of CHEs at individual points or stations, assessments of features for regional CHEs (RCHEs), which have a specific impact area and duration, are still lacking. This study aimed to investigate the climatic characteristics of RCHEs in mainland China by applying an objective identification technique for regional extreme events based on a compound index. The results show that 379 RCHEs were identified during 1961–2020, most of the events had a duration of 5–11 d and a maximum impacted area of approximately 460 10 4 km 2 . Long-duration RCHEs were found to have vigorous extreme intensity and large maximum impacted area. The middle and lower reaches of the Yangtze River were most susceptible to RCHEs, while the Yellow River Valley had the most robust positive trend of frequency for RCHEs, suggesting a significant risk of compound temperature disasters in this region. Furthermore, RCHEs in mainland China showed significant increasing trends in several aspects, such as annual frequency, integrated index, and single indices (e.g. duration, accumulated intensity, accumulated impacted area, and extreme intensity). These upward trends were accompanied by evident interdecadal variations, with low values before 1992 and high values after 1992. This study provides valuable insights into understanding and monitoring CHEs in China from the perspective of regional extremes.

Seasonal prediction of tropical cyclone (TC) activity has been a hot research theme in the past decades. Usually, the tropical sea surface temperatures (SSTs) provide considerable predictability sources for the western North Pacific (WNP) TC activity. Here, we emphasized that the Chukchi-Beaufort (C-B) and Greenland (GL) sea ice variability is closely linked to the year-to-year variations of the early autumn WNP TC formation frequency (TCF). Observational and numerical evidence proved that the excessive C-B and GL sea ice sustains from August to the following early autumn and triggers the southeastward propagation of the Rossby wave trains originating from the Arctic across Western Eurasia (Okhotsk Sea) to the WNP. The resultant anomalous low pressure over WNP provides suitable environmental conditions for TC formation―the enhancement of the lower-level relative vorticity and water moisture, and the decrease of vertical wind shear. For the reduced sea ice, an opposite situation tends to emerge. The persistent combined sea ice signal makes it a physically meaningful precursor for TCF prediction. The cross-validated hindcast and independent forecast based on both the tropical SST and the Arctic sea ice precursors present that the TCF index is predicted with much higher correlation coefficients than those of the empirical models with only the tropical SST predictors. The results demonstrate that the Arctic sea ice truly promotes the seasonal prediction capability of the WNP TCF.

The Indian summer monsoon (ISM) tends to be intensified in a global-warming scenario, with a weakened linkage with El Niño–Southern Oscillation (ENSO), but how the East Asian summer monsoon (EASM) responds is still an open question. This study investigates the responses of the EASM from observations, theoretical, and modeling perspectives. Observational and theoretical evidence demonstrates that, in contrast to the dramatic global-warming trend within the past 50 years, the regional-mean EASM rainfall is basically dominated by considerable interannual-to-decadal fluctuations, concurrent with enhanced precipitation over the middle and lower reaches of the Yangtze River and over southern Japan and suppressed rainfall amount over the South China and Philippine Seas. From 1958 through 2008, the EASM circulation exhibits a southward shift in its major components (the subtropical westerly jet stream, the western Pacific Ocean subtropical high, the subtropical mei-yu–baiu–changma front, and the tropical monsoon trough). Such a southward shift is very likely or in part due to the meridional asymmetric warming with the most prominent surface warming in the midhigh latitudes (45°–60°N), which induces a weakened meridional thermal contrast over eastern Asia. Another notable feature is the enhanced ENSO–EASM relationship within the past 50 years, which is opposite to the ISM. Fourteen state-of-the-art coupled models from the Intergovernmental Panel on Climate Change show that the EASM strength does not respond with any pronounced trend to the global-warming ‘‘A1B’’ forcing scenario (with an atmospheric CO₂ concentration of 720 ppm) but shows interannual-to-decadal variations in the twenty-first century (2000–99). These results indicate that the primary response of the EASM to a warming climate may be a position change instead of an intensity change, and such position change may lead to spatial coexistence of floods and droughts over eastern Asia as has been observed in the past 50 years.