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: Climatology, also named the "Climate Normal" by World Meteorological Organization (WMO), is critical for characterizing historical or near-future weather and climate states, and is usually calculated for a uniform 30-year period according to the WMO definitions. However, in addition to external forcing changes, climatology can be impacted by internal climate variabilities on multi-decadal and longer time scales. Here we introduce a simple sampling model and conduct three equilibrium climate sensitivity experiments using a Global Climate Model EC-Earth to quantify the potential uncertainties in estimating equilibrium climate change. We take into account the effect of multi-centennial variability in the climate system, which has been identified in paleo-climate proxy records and long climate model simulations. For the time series that contain multi-centennial oscillation, the estimate of climate change refers to the difference between two equilibrium climate states that may have significant uncertainty due to random selection of the phase location of the sampling. Our exercises with EC-Earth experiments show that such uncertainties are significant at high latitudes where low-frequency oscillations dominate. The accuracy of the estimated climate state at mid-to-high latitudes in the Northern Hemisphere is mainly impacted by the multi-centennial oscillation, while the uncertainty in mid-to-high Southern Hemisphere is affected by the oscillation on multi-centennial to millennial time scales. We show that applying quasi-periodic sampling in calculating the equilibrium climate state can significantly reduce such uncertainties. This work reminds us that the potential uncertainties induced by multi-centennial climate variability cannot be ignored when the length of sampling data is limited.

Description: The underground space represented by coal mines, subways, comprehensive pipe corridors, etc. is in rapid development, and the demand for high-precision positioning and navigation for unmanned and intelligent underground space is increasing. The narrow and closed physical structure and complex channel characteristics of the underground space bring great challenges to high-precision positioning and navigation. The problems and challenges are analyzed in depth, and a high-precision positioning and navigation system suitable for complex underground space is designed in the paper. The system adopts a network +map + terminal architecture, and builds a hybrid positioning network based on the new UWB, Beidou pseudo-satellite, near-ultrasonic positioning systems to achieve the full scene coverage of underground space. Efficient and intelligent positioning and navigation services are realized through network map fusion support. Partial test results are given. Compared with the commonly used radio position system, it has achieved significant improvement in accuracy and coverage.

Description: The present study investigates the characteristics and possible origins of the synoptic and intraseasonal variability of the extreme heavy rainfall (EHR) event in Henan Province, China in July 2021. Two dominant modes with periods about 8 days and 10–40 days feature the Henan EHR event and explain more than 80% of total rainfall. The synoptic variability of the Henan EHR event can be attributed to the northwestward-propagating synoptic-scale wave train modulated by the monsoon trough over the western North Pacific. A northernmost-displacement monsoon trough in July 2021 (~23.2°N) would facilitate the synoptic-scale wave train to propagate farther northwestward, which reaches to the subtropical region and thus influences the Henan EHR event. The intraseasonal variability of the Henan EHR event is tightly related to the meridional dipole pattern with an anticyclonic circulation over North China and Sea of Japan and a cyclonic circulation over the western North Pacific. Both tropical and extratropical signals are responsible for the intraseasonal variability of the Henan rainfall, including the northward-propagating Boreal Summer Intraseasonal Oscillation, mid-latitude wave train over the Eurasian continent and air-sea interaction over the Kuroshio Extension region. The synoptic and intraseasonal atmospheric circulations favor abundant moisture transporting to Henan and strong ascending flow, jointly leading to the rainfall extreme therein. The results implicate that these tropical and extratropical forcings may be the potential precursors for heavy rainfalls in Henan Province or even the northern Central China.

Description: As the result of changes in ice dynamics and weather-driven changes on the surface, surface elevation changes over ice sheets are sensitive to climate forcing. Thus, long-term surface elevation changes over ice sheets of Greenland and Antarctica are of essential to assess the impact of climate change. Here, a dataset of monthly surface elevation time series over ice sheets of Greenland and Antarctica at 5km grid resolution using ERS-1, ERS-2, Envisat, and CryoSat-2 radar altimeter observations from August 1991 to December 2020. An updated plane-fitting least-squares regression strategy and Empirical orthogonal function (EOF) reconstruction were applied to ensure the accuracy and self-consistency of the merged elevation time series in the data processing. In addition, the cross-comparison with the IceBridge airborne laser altimeter observations confirmed that our merged dataset is reliable. Benefiting from its high temporal and spatial resolutions, the evolution processes on multiple temporal (up to 30 years) of ice loss from the main outflow glaciers in Greenland and Antarctica can be derived in detail. The spatiotemporal patterns of accelerating or decelerating surface elevation changes over ice sheet related to ENSO (for the Antarctic Ice sheet) and NAO (for the Greenland Ice sheet) indicated that climate forcing shifts oceanic forcing or atmospheric forcing in some way to affect ice sheet changes. Our merged time series provide a vital dataset for exploring the processes of climate forcing driving ice sheet change.

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.