This paper documents a decadal strengthened co-variability of the Antarctic Oscillation （AAO） and ENSO in austral spring after the mid-1990s. During the period 1979-93, the ENSO （AAO） spatial signatures are restri...This paper documents a decadal strengthened co-variability of the Antarctic Oscillation （AAO） and ENSO in austral spring after the mid-1990s. During the period 1979-93, the ENSO （AAO） spatial signatures are restricted to the tropicsmidlatitudes （Antarctic-midlatitudes） of the Southern Hemisphere （SH）, with a weak connection between the two oscillations. Comparatively, after the mid-1990s, the E1 Nifio-related atmospheric anomalies project on a negative AAO pattern with a barotropic structure in the mid-high latitudes of the SH. The expansion of E1 Nifio-related air temperature anomalies have a heightened impact on the meridional thermal structure of the SH, contributing to a weakened circumpolar westerly and strengthened subtropical jet. Meanwhile, the ENSO-related southern three-cell circulations expand poleward and then strongly couple the Antarctic and the tropics. Numerical simulation results suggest that the intensified connection between ENSO and SST in the South Pacific since the mid-1990s is responsible for the strengthened AAO-ENSO relationship.展开更多
Chemical investigation on the medicinal fungus Ganoderma australe led to the identification of ten new nor-lanostane triterpenes,namely two hexa-nor ones,ganoaustratetraenones A(1)and B(2),five penta-nor ones,ganoaust...Chemical investigation on the medicinal fungus Ganoderma australe led to the identification of ten new nor-lanostane triterpenes,namely two hexa-nor ones,ganoaustratetraenones A(1)and B(2),five penta-nor ones,ganoaustraldehydes A-E(3-7),and three tetra-nor ones ganoaustrenoic acids A-C(8-10).The chemical structures along with the absolute configurations were determined by extensive spectroscopic analysis of 1D&2D NMR and HRESIMS data.The postulated biosynthesis pathways of these compounds were proposed.Ganoaustraldehydes A(3)and B(4)showed moderate inhibition against nitric oxide production in RAW264.7 macrophage cells with the respec-tive IC_(50) values of 32.5,34.2μM(the IC_(50) of positive control pyrrolidine dithiocarbamate was 20.0μM).展开更多
Surface ozone(O3)is a secondary pollutant harmful to human health and a greenhouse gas which is one of the prime climate forcers.Due to the clean atmospheric environment of the Antarctic region and given the complexit...Surface ozone(O3)is a secondary pollutant harmful to human health and a greenhouse gas which is one of the prime climate forcers.Due to the clean atmospheric environment of the Antarctic region and given the complexity of O3 chemistry,the observation of surface O3 variability in this region is necessary in the quest to better understand the potential sources and sink of polar surface O3.In this paper,we highlighted our observations on O3 variability at the Great Wall Station(GWS)during austral summer in December 2018 and January 2019.The continuous surface O3 measurement at the GWS,Antarctica was carried out using the Ecotech Ozone analyzer.To understand the roles of the meteorological conditions on the temporal variations of O3,meteorological data was obtained from the conventional auto-observational station at the GWS.The Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model was employed to investigate the air mass transport over the region.The observed austral summer surface O3 concentrations at the GWS exhibited variability and were significantly lower than those previously observed at other permanent coastal stations in Antarctica.The surface ozone variability at the GWS was strongly influenced by the synoptic change of air mass origin although the roles of photochemistry production and destruction were still uncertain.Marine characteristics and stable surface O3 characterized the air masses that reached the GWS.The unique characteristic of surface O3 at the coastal site of GWS was emphasized by its synoptic air mass characteristics,which displayed a significant influence on surface O3 variability.Air mass that traveled over the ocean with relatively shorter distance was linked to the lower O3 level,whereby the marine transport of reactive bromine(Br)species was thought to play a significant role in the tropospheric chemistry that leads to O3 destruction.Meanwhile,the diurnal variation indicated that the O3 background concentration levels were not strongly associated with the local atmospheric conditions.展开更多
-STD Data obtained from the Third Chinese National Antarctic Research Expedition from January to February 1987 in the region near the South Shetland Islands are used to investigate an oceanic front, continental water ...-STD Data obtained from the Third Chinese National Antarctic Research Expedition from January to February 1987 in the region near the South Shetland Islands are used to investigate an oceanic front, continental water boundary (CWB), north of the South Shetland Islands. The characteristics of the CWB in surface and subsurface layers as well as deep layer are discussed respectively. The estimations of the geostrophic currents and the baroclinic deformed radius Rbc in this area show that the flow along the front is in the geostrophic equilibrium approximately, and the formation of the front is mainly due to the strong boundary current north of the South Shetland Islands. Its length along the front is estimated to be about 360 km and its width across the front is about 30 km.展开更多
Data-driven deep-learning models have shown outstanding performance in global weather forecasting.Understanding the dynamic response processes within these models is crucial for comprehending the embedded physical pro...Data-driven deep-learning models have shown outstanding performance in global weather forecasting.Understanding the dynamic response processes within these models is crucial for comprehending the embedded physical processes and sources of predictability.By applying the classic tropical steady heating experiment to the Pangu-Weather deep-learning model during the austral winter background state,we observe a classic Matsuno-Gill response in the tropics and planetary Rossby waves propagating to the polar regions.The results of the Pangu-Weather model are consistent with those of traditional physics-based general circulation models(GCMs):convective heating forcing in the tropical Atlantic and western Indian Ocean,and convective cooling forcing in the Maritime Continent all deepen the Amundsen Sea Low(ASL),while convective heating forcing in the western Pacific weakens the ASL.The Pangu-Weather model has learned that these tropical basins jointly and linearly regulate the atmospheric circulation around West Antarctica through Rossby waves.However,the Pangu-Weather model overestimates(underestimates)atmospheric responses of heating in the tropical Pacific(Indian and Atlantic)Ocean compared with traditional GCMs,with a much larger contribution of Pacific heating forcing than other basins in changes of the ASL.The physics learned from reanalysis data may be the source of these deep-learning models’predictability,and the accuracy of extended-range forecasting and the potential of seasonal forecasting using deep-learning models may be influenced by overestimation or underestimation of the role of the tropical Pacific,Indian,and Atlantic Oceans.展开更多
Aims Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations.Seeds with dormancy may especially benefit after disperser gut passage.However,the ways in whi...Aims Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations.Seeds with dormancy may especially benefit after disperser gut passage.However,the ways in which gut passage affect the germination of plant species with physiological dormancy remain unclear.Here,we experimentally assessed the mutualistic interaction between the Austral parakeet(Enicognathus ferrugineus)as a disperser of calafate(Berberis microphylla),a thorny bush inhabiting the understory of the Austral temperate forests of South America with seeds that are characterized by deep physiological dormancy.Methods Germination success and viability of calafate seeds obtained from faeces and from intact fruits were tested under four treatments:(i)digested seeds,(ii)digested seeds with faecal extract,(iii)intact seeds from fruit and(iv)intact seeds from fruit with pulp.Important Findings About 65%of the Austral parakeet droppings contained calafate seeds.Viability of seeds did not differ between treatments.However,germination was significantly higher in digested seeds than in intact seeds from fruits,while no difference was found between faecal and pulp extracts.Neither faecal matter nor fruit pulp provided seeds with any ecological advantages derived from enhancing germinability,but did confer some disadvantage in germination time.Faecal matter is expected to be completely lacking around seeds after several months under snow before germinating in the following spring,given intense washing due to persistent rain and the spring thaw in the Patagonian Andes.The higher germinability along with faster germination of digested seeds supports the hypothesis of a legitimate mutualistic interaction between Austral parakeets and calafate.We hypothesized that the passage through the disperser digestive tract might break physiological dormancy as differences in germinability between ingested and non-ingested seeds.Our results highlight the relevant role of endozoochory in plant species with physiological dormancy living in highly seasonal environments.展开更多
Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic ins...Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.展开更多
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.41421004 and 41210007)the Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY201306026)
文摘This paper documents a decadal strengthened co-variability of the Antarctic Oscillation （AAO） and ENSO in austral spring after the mid-1990s. During the period 1979-93, the ENSO （AAO） spatial signatures are restricted to the tropicsmidlatitudes （Antarctic-midlatitudes） of the Southern Hemisphere （SH）, with a weak connection between the two oscillations. Comparatively, after the mid-1990s, the E1 Nifio-related atmospheric anomalies project on a negative AAO pattern with a barotropic structure in the mid-high latitudes of the SH. The expansion of E1 Nifio-related air temperature anomalies have a heightened impact on the meridional thermal structure of the SH, contributing to a weakened circumpolar westerly and strengthened subtropical jet. Meanwhile, the ENSO-related southern three-cell circulations expand poleward and then strongly couple the Antarctic and the tropics. Numerical simulation results suggest that the intensified connection between ENSO and SST in the South Pacific since the mid-1990s is responsible for the strengthened AAO-ENSO relationship.
基金National Natural Science Foundation of China (grant numbers 21961142008,22177138) for fundings.
文摘Chemical investigation on the medicinal fungus Ganoderma australe led to the identification of ten new nor-lanostane triterpenes,namely two hexa-nor ones,ganoaustratetraenones A(1)and B(2),five penta-nor ones,ganoaustraldehydes A-E(3-7),and three tetra-nor ones ganoaustrenoic acids A-C(8-10).The chemical structures along with the absolute configurations were determined by extensive spectroscopic analysis of 1D&2D NMR and HRESIMS data.The postulated biosynthesis pathways of these compounds were proposed.Ganoaustraldehydes A(3)and B(4)showed moderate inhibition against nitric oxide production in RAW264.7 macrophage cells with the respec-tive IC_(50) values of 32.5,34.2μM(the IC_(50) of positive control pyrrolidine dithiocarbamate was 20.0μM).
基金funded by the Sultan Mizan Antarctic Research Foundation(YPASM,2017)Malaysiasupported by the Chinese Arctic and Antarctic Administration(CAA)support by Universiti Malaysia Sabah(UMS)。
文摘Surface ozone(O3)is a secondary pollutant harmful to human health and a greenhouse gas which is one of the prime climate forcers.Due to the clean atmospheric environment of the Antarctic region and given the complexity of O3 chemistry,the observation of surface O3 variability in this region is necessary in the quest to better understand the potential sources and sink of polar surface O3.In this paper,we highlighted our observations on O3 variability at the Great Wall Station(GWS)during austral summer in December 2018 and January 2019.The continuous surface O3 measurement at the GWS,Antarctica was carried out using the Ecotech Ozone analyzer.To understand the roles of the meteorological conditions on the temporal variations of O3,meteorological data was obtained from the conventional auto-observational station at the GWS.The Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model was employed to investigate the air mass transport over the region.The observed austral summer surface O3 concentrations at the GWS exhibited variability and were significantly lower than those previously observed at other permanent coastal stations in Antarctica.The surface ozone variability at the GWS was strongly influenced by the synoptic change of air mass origin although the roles of photochemistry production and destruction were still uncertain.Marine characteristics and stable surface O3 characterized the air masses that reached the GWS.The unique characteristic of surface O3 at the coastal site of GWS was emphasized by its synoptic air mass characteristics,which displayed a significant influence on surface O3 variability.Air mass that traveled over the ocean with relatively shorter distance was linked to the lower O3 level,whereby the marine transport of reactive bromine(Br)species was thought to play a significant role in the tropospheric chemistry that leads to O3 destruction.Meanwhile,the diurnal variation indicated that the O3 background concentration levels were not strongly associated with the local atmospheric conditions.
文摘-STD Data obtained from the Third Chinese National Antarctic Research Expedition from January to February 1987 in the region near the South Shetland Islands are used to investigate an oceanic front, continental water boundary (CWB), north of the South Shetland Islands. The characteristics of the CWB in surface and subsurface layers as well as deep layer are discussed respectively. The estimations of the geostrophic currents and the baroclinic deformed radius Rbc in this area show that the flow along the front is in the geostrophic equilibrium approximately, and the formation of the front is mainly due to the strong boundary current north of the South Shetland Islands. Its length along the front is estimated to be about 360 km and its width across the front is about 30 km.
基金supported by the National Natural Science Foundation of China (Grant Nos.42288101 and 42175025)the National Key Research and Devel-opment Program of China (Grant No. 2023YFF0806700)
文摘Data-driven deep-learning models have shown outstanding performance in global weather forecasting.Understanding the dynamic response processes within these models is crucial for comprehending the embedded physical processes and sources of predictability.By applying the classic tropical steady heating experiment to the Pangu-Weather deep-learning model during the austral winter background state,we observe a classic Matsuno-Gill response in the tropics and planetary Rossby waves propagating to the polar regions.The results of the Pangu-Weather model are consistent with those of traditional physics-based general circulation models(GCMs):convective heating forcing in the tropical Atlantic and western Indian Ocean,and convective cooling forcing in the Maritime Continent all deepen the Amundsen Sea Low(ASL),while convective heating forcing in the western Pacific weakens the ASL.The Pangu-Weather model has learned that these tropical basins jointly and linearly regulate the atmospheric circulation around West Antarctica through Rossby waves.However,the Pangu-Weather model overestimates(underestimates)atmospheric responses of heating in the tropical Pacific(Indian and Atlantic)Ocean compared with traditional GCMs,with a much larger contribution of Pacific heating forcing than other basins in changes of the ASL.The physics learned from reanalysis data may be the source of these deep-learning models’predictability,and the accuracy of extended-range forecasting and the potential of seasonal forecasting using deep-learning models may be influenced by overestimation or underestimation of the role of the tropical Pacific,Indian,and Atlantic Oceans.
基金K.S.and S.A.L.were funded by the projects PICT 2015-2072 and PICT 2018-1623.
文摘Aims Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations.Seeds with dormancy may especially benefit after disperser gut passage.However,the ways in which gut passage affect the germination of plant species with physiological dormancy remain unclear.Here,we experimentally assessed the mutualistic interaction between the Austral parakeet(Enicognathus ferrugineus)as a disperser of calafate(Berberis microphylla),a thorny bush inhabiting the understory of the Austral temperate forests of South America with seeds that are characterized by deep physiological dormancy.Methods Germination success and viability of calafate seeds obtained from faeces and from intact fruits were tested under four treatments:(i)digested seeds,(ii)digested seeds with faecal extract,(iii)intact seeds from fruit and(iv)intact seeds from fruit with pulp.Important Findings About 65%of the Austral parakeet droppings contained calafate seeds.Viability of seeds did not differ between treatments.However,germination was significantly higher in digested seeds than in intact seeds from fruits,while no difference was found between faecal and pulp extracts.Neither faecal matter nor fruit pulp provided seeds with any ecological advantages derived from enhancing germinability,but did confer some disadvantage in germination time.Faecal matter is expected to be completely lacking around seeds after several months under snow before germinating in the following spring,given intense washing due to persistent rain and the spring thaw in the Patagonian Andes.The higher germinability along with faster germination of digested seeds supports the hypothesis of a legitimate mutualistic interaction between Austral parakeets and calafate.We hypothesized that the passage through the disperser digestive tract might break physiological dormancy as differences in germinability between ingested and non-ingested seeds.Our results highlight the relevant role of endozoochory in plant species with physiological dormancy living in highly seasonal environments.
文摘Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.
