Description: Ambient conditions shape microbiome responses to both short- and long-duration environment changes through processes including physiological acclimation, compositional shifts, and evolution. Thus, we predict that microbial communities inhabiting locations with larger diel, episodic, and annual variability in temperature and pH should be less sensitive to shifts in these climate-change factors. To test this hypothesis, we compared responses of surface ocean microbes from more variable (nearshore) and more constant (offshore) sites to short-term factorial warming (+3 °C) and/or acidification (pH -0.3). In all cases, warming alone significantly altered microbial community composition, while acidification had a minor influence. Compared with nearshore microbes, warmed offshore microbiomes exhibited larger changes in community composition, phylotype abundances, respiration rates, and metatranscriptomes, suggesting increased sensitivity of microbes from the less-variable environment. Moreover, while warming increased respiration rates, offshore metatranscriptomes yielded evidence of thermal stress responses in protein synthesis, heat shock proteins, and regulation. Future oceans with warmer waters may enhance overall metabolic and biogeochemical rates, but they will host altered microbial communities, especially in relatively thermally stable regions of the oceans.

Description: A severe flooding hit the region of central east China to southern Japan in summer 2020. It is found that the extremely strong rainfall experienced pronounced subseasonal variation, dominated by a quasi-biweekly oscillation (QBWO) mode. The analysis of streamfunction of water vapor flux demonstrates that a large amount of water vapor eastward zonal transport from the Bay of Bengal and Indo-China and northward transport from the South China Sea provided the background moisture supply for the rainfall. The quasi-biweekly anomalies of potential and divergent component of vertically integrated water vapor flux played an important role in maintaining the subseasonal variability of extreme rainfall. The diagnosis of moisture tendency budget shows that the enhanced moisture closely related to the quasi-biweekly fluctuated rainfall was primarily attributed to the moisture convergence. Further analysis of time-scale decomposition in the moisture convergence indicates that the convergence of background mean specific humidity by the QBWO flow and convergence of QBWO specific humidity by the mean flow played dominant roles in contributing to the positive moisture tendency. In combination with adiabatic ascent over the rainfall region induced by the warm temperature advection, the boundary layer moisture convergence strengthened the upward transport of water vapor to moisten the middle troposphere, favoring the persistence of rainfall. The vertical moisture transport associated with boundary layer convergence was of critical importance in causing low-level tropospheric moistening.

Description: The East Asian winter monsoon (EAWM) exerts impacts on climate in the regions from East Asia down to the Maritime Continent. The El Niño-Southern Oscillation (ENSO) affects not only the tropical climate, but also the extratropical climate. This study evaluates the relationship between El Niño-Southern Oscillation (ENSO) and the East Asian winter monsoon (EAWM) in 26 Coupled Model Intercomparison Project phase 6 (CMIP6) models. Results show that the model’s ability of simulating the ENSO-EAWM relationship is more dependent upon the longitudinal extension of ENSO-related equatorial Pacific sea surface temperature (SST) anomalies than the amplitude of the equatorial central-eastern Pacific SST anomalies. The influence of the amplitude of ENSO on the simulation of the ENSO-EAWM relationship depends on the westward extension of ENSO-related equatorial Pacific SST anomalies. Another factor for the model’s ability of simulating the ENSO-EAWM relationship is the SST anomalies in the tropical western North Pacific (WNP). A westward extension of the equatorial Pacific SST anomalies shifts the west branch of anomalous Walker circulation too far westward, which causes westward displaced anomalous ascending (descending) motion around the Philippine Sea through modulating regional meridional vertical circulation in El Niño (La Niña) years. The weak SST anomalies in the tropical WNP lead to the failure of inducing anomalous lower-level anticyclone (cyclone) over the Philippine Sea through a Rossby wave response in El Niño (La Niña) years. The accompanying weak anomalous lower-level southwesterly (northeasterly) winds along the west flank of the anomalous anticyclone (cyclone) account for the weak ENSO-EAWM relationship.

Description: An open-ocean polynya is an offshore area where the sea ice is significantly less than that of its surrounding area. Polynyas are known as oases in Antarctic for driving the interactions between the atmosphere and the ocean. Extensive studies have addressed the characteristics and mechanisms of open-ocean polynyas in the Weddell and Cosmonaut Seas. The purpose of this study is to indicate the existence of more persistent open-ocean polynyas in the Cooperation Sea and propose the atmospheric and oceanic forcing mechanisms responsible for the formation of the open-ocean polynyas. Our results offer a more complete circumpolar view of open-ocean polynyas in the Southern Ocean and have implications for physical, biological, and biogeochemical studies of the Southern Ocean. Future efforts should be particularly devoted to more extensively observing the ocean circulation to understand the variability of open-ocean polynyas in the Cooperation Sea.

Description: The bathymetry around Antarctica can govern the shelf sea circulations and play a key role in conditioning water masses. In Prydz Bay, the Prydz Bay Gyre and coastal currents are also determined by the continental shelf topography. However, due to the paucity of beam echo sounding data, the bathymetric datasets in Prydz Bay still have large uncertainties. With the aid of in situ hydrographic observations, this study focuses on the correction of an up-to-date bathymetric dataset and the resultant influences on the shelf circulation and the basal melting of the ice shelves. The corrected bathymetry mainly improves the biased shallow representations in the uncorrected bathymetric data set, with a maximum change of ~500 m deepening in the eastern flank of Prydz Bay. Sensitivity numerical experiments show that the bathymetric corrections in Prydz Bay have a significant impact on the circulation pattern and onshore warm water intrusions. In addition, the corrected bathymetry markedly decreases the heat transport towards the calving front of the Amery Ice Shelf. The onshore heat transport reduces by ~22.18% from ~5.23×10〈sup〉13〈/sup〉 J s〈sup〉-1〈/sup〉 to ~4.07×10〈sup〉13〈/sup〉 J s〈sup〉-1〈/sup〉 over the outer shelf. Over the inner shelf, the heat transport towards the Amery Ice Shelf reduces by ~18.15% from ~5.95×10〈sup〉13〈/sup〉 J s〈sup〉-1 〈/sup〉to ~4.87×10〈sup〉13〈/sup〉 J s〈sup〉-1〈/sup〉. Consequently, the temporally and spatially averaged basal melting rate of the Amery Ice Shelf reduces by ~13.04% from ~0.69 m yr〈sup〉-1〈/sup〉 to ~0.60 m yr〈sup〉-1〈/sup〉.

Description: Numerous studies have indicated that the atmospheric heat source (AHS) over the Tibetan Plateau (TP) is highly correlated with the western North Pacific anomalous anticyclone (WNPAC) in summer. However, such an interannual relationship has been weakened since the late 1990s. The present work shows that the TP AHS was significantly and positively correlated with the WNPAC in 1979–1999 (P1), while this relationship became insignificant hereafter (2000–2020; P2). We identify that the long-term change in the upper-level atmospheric circulation over the TP is responsible for weakening the relationship. An obvious upper-level anticyclonic trend occurred over the northeastern TP in the past four decades, with an easterly trend on the anticyclone’s southern flank, representing anomalous westerlies during P1 but anomalous easterlies during P2 over the main portion of the TP. With the anomalous upper-level westerlies in P1, the abnormal high pressure induced by the TP heating (i.e. AHS) extended downstream in the upper troposphere. Subsequently, anomalous descending motions formed over the northwestern Pacific due to the eastward-extended high pressure, together with the vertical transport of negative relative vorticity, favorable for the enhancement of the WNPAC. Whereas in P2, the TP heating-induced abnormal high pressure was confined over the southern TP due to the anomalous easterlies, suppressing its downstream influence and finally breaking the connection between the TP AHS and the WNPAC. Modeling results from both LBM sensitivity experiments and CESM large ensemble dataset further confirm the important role of the change in background circulation in weakening the relationship.

Description: This study investigates the impact of vegetation-climate feedback on the global monsoon (GM) during two key periods, the Last Interglacial (LIG, 127 000 years BP) and the mid-Holocene (MH, 6 000 years BP), using the earth system model EC-Earth3. The simulations reveal that changes in vegetation lead to an expansion of the GM area by 0.2% and 1.1% during the LIG and MH, respectively. Notably, the North African region experiences the most significant increase in vegetation, resulting in the largest expansion in the North African monsoon area, expanding by 7.6% and 6.0% during the LIG and MH, respectively. The enhanced vegetation feedbacks lead to surface warming in the Sahara, deepening of the Saharan Heat Low, strengthening of the monsoonal flow across North Africa, and increased rainfall in the region. However, the change in vegetation type resulted in opposite effects in the Asian and Australian monsoon regions during the LIG and MH periods. The Asian monsoon area reduces by 1.8% during the LIG and expands by 0.2% during the MH, while the Australian monsoon area reduces by 1.7% during the LIG and expands by 1.0% during the MH. These findings highlight that vegetation feedback has different impacts on the global monsoon during the LIG and MH periods. Overall, this study sheds light on the importance of vegetation feedback in shaping the global monsoon during critical periods in Earth's history.

Description: In July and August of 2022, unprecedented and long-lasting heatwaves attacked central and eastern China (CEC); and the most affected area was in the Yangtze River (YR) basin. The extreme heatwaves and associated drought and wildfire had significant social impacts, but the underlying mechanisms remain unknown. Observational analysis indicates that the heatwaves were regulated by anomalous anticyclone in the mid-upper troposphere over northern CEC. Specifically, the easterly anomalies at the southern flank of the anticyclone caused air isentropic sliding and transported low moist enthalpy (cold and dry) air to the YR basin, contributing to anomalous sinking motions and extreme heatwaves. In comparison, heatwaves were more serious in August than in July due to stronger upper-level anomalous anticyclone and associated easterlies. Importantly, different mechanisms were responsible for the heatwaves in the two months. In July, the relatively weaker anticyclonic anomaly over northern CEC was dominated by the forcing of diabatic heating over northwestern South Asia (NWSA), corresponding with the record-breaking rainfall in and around Pakistan. In August, a powerful anticyclonic condition for the CEC heatwaves originated from an extreme silk road pattern (SRP), superposing the effect of NWSA diabatic heating due to persistent downpour. We notice that another upstream anticyclonic node in the SRP also created heatwaves in Europe. Therefore, the CEC extreme heat was actually associated with other concurrent extremes over the Eurasian continent through large-scale atmospheric teleconnections in 2022.

Description: Recent annual assessments of present-day and future climate variability provided by the World Meteorological Organization have motivated the need for the attribution of environmental change, separating climate forcing agents from large-scale natural climate variability. To address this need operational forecasting systems are essential together with sustained, comprehensive and relevant observations for assessing current climate and climate forcers. The World Climate Research Programme Light House Activity – Explaining and Predicting Earth System Change (EPESC) – will cast a new light on the proximal drivers of regional climate variation on annual-to-decadal (A2D) timescales. The EPESC is focused on three distinct yet interrelated themes: The monitoring and modelling of Earth system change; the integrated attribution, prediction and projection of A2D changes including the potential for extremes; and the assessment of current and future hazards. In this presentation we will outline the current and future requirements of A2D prediction and projection, including the requisite infrastructure of operational attribution and the need for comprehensive whole-atmosphere observations, such as those which will be provided by the proposed Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT), recently selected by the European Space Agency (ESA) as one of four candidates for the Earth Explorer 11 mission.

Description: Due to different reanalysis methods and input data, there exist big discrepancies between hydrological models from regions to regions. Therefore, accuracy assessment of different models is necessary before applications in specific areas. In this report, six hydrological models, including GLDAS, FLDAS, ERA5, MERRA-Land, NCEP and WGHM were evaluated and analyzed through inter-comparison between models and outer-comparison with Global Positioning System (GPS) station height time series, GRACE/GRACE-FO RL06 Mascon solutions, and Precipitation data from Global Precipitation Climatology Centre (CPCC) for a comprehensive assessment of model differences. We then try to combine the six models through variance component estimation (VCE), entropy weight method (EWF), coefficient of variation method (CVM) and other mathematical models, so as to improve the accuracy, integrity and applicability of hydrological models. Our results show that the root mean square (RMS) of global GPS height time series improves by up to 17% after correcting the hydrological effect obtained from combined models compared with that from individual models, while the correlation with rainfall also improves by 30% at most. Compared with TWSC derived from satellite gravity inversion, the correlation coefficient increases from 0.2 to 0.8 at the highest. Finally, the combined methods exhibit much higher signal-to-noise ratio (SNR) value than that of the pre-combined models, and the VCE combined model performs as the optimal hydrology model to correct the GPS height. Therefore, we conclude that the combined hydrological model could provide a better data source for monitoring hydrological changes and surface load deformation at a global scale.