共查询到13条相似文献，搜索用时 187 毫秒
1.
You-Soon Chang 《Ocean Dynamics》2014,64(6):823-832
A previous study (Lyman et al., Nature 465:334–337, 2010) showed a robust warming signal of the global upper ocean (0–700 m). They examined several sources of uncertainty that contribute to differences among heat content estimations. However, their focus was limited to globally averaged estimation. This study presents the spatial pattern of the global heat content change based on observed gridded datasets (Levitus et al., Geophys Res Lett 36:L07608, 2009). The western Pacific, Atlantic, and Indian Oceans showed significant warming trends, whereas eastern Pacific and some areas of the Gulf Stream experienced negative trends during 1993–2009. Steady warming trend was obtained from the first EOF mode when El Nino and Southern Oscillation (ENSO)-related signals were removed. This result implies that the rapid increase in heat content of the upper ocean around 2000–2005 is not related to a sampling transition from XBT to Argo observations but is associated with a natural variability dominated by strong ENSO-related signals. 相似文献
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<正>Previous studies have widely reported the linkages between Asian-Australian monsoon and the ENSO(Wu, 2008; Azad and Rajeevan, 2016; Chen et al., 2020; Shekhar et al., 2022;Zhang J et al., 2022; Chen et al., 2023; Hau et al., 2023;Heidemann et al., 2023). 相似文献
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《中国科学:地球科学(英文版)》2021,(6)
The unexpected global warming slowdown during 1998–2013 challenges the existing scientific understanding of global temperature change mechanisms, and thus the simulation and prediction ability of state-of-the-art climate models since most models participating in phase 5 of the Coupled Model Intercomparison Project(CMIP5) cannot simulate it. Here, we examine whether the new-generation climate models in CMIP6 can reproduce the recent global warming slowdown, and further evaluate their capacities for simulating key-scale natural variabilities which are the most likely causes of the slowdown. The results show that although the CMIP6 models present some encouraging improvements when compared with CMIP5, most of them still fail to reproduce the warming slowdown. They considerably overestimate the warming rate observed in 1998–2013,exhibiting an obvious warming acceleration rather than the observed deceleration. This is probably associated with their deficiencies in simulating the distinct temperature change signals from the human-induced long-term warming trend and/or the three crucial natural variabilities at interannual, interdecadal, and multidecadal scales. In contrast, the 4 models that can successfully reproduce the slowdown show relatively high skills in simulating the long-term warming trend and the three keyscale natural variabilities. Our work may provide important insight for the simulation and prediction of near-term climate changes. 相似文献
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The tropical Pacific experienced a sustained warm sea surface condition that started in 2014 and a very strong El Nio event in 2015. One striking feature of this event was the horseshoe-like pattern of positive subsurface thermal anomalies that was sustained in the western-central equatorial Pacific throughout 2014–2015. Observational data and an intermediate ocean model are used to describe the sea surface temperature(SST) evolution during 2014–2015. Emphasis is placed on the processes involved in the 2015 El Nio event and their relationships with SST anomalies, including remote effects associated with the propagation and reflection of oceanic equatorial waves(as indicated in sea level(SL) signals) at the boundaries and local effects of the positive subsurface thermal anomalies. It is demonstrated that the positive subsurface thermal anomaly pattern that was sustained throughout 2014–2015 played an important role in maintaining warm SST anomalies in the equatorial Pacific. Further analyses of the SST budget revealed the dominant processes contributing to SST anomalies during 2014–2015. These analyses provide an improved understanding of the extent to which processes associated with the 2015 El Nio event are consistent with current El Nio and Southern Oscillation theories. 相似文献
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《Limnologica》2020
Changes in the ice phenology, seasonal temperature and extreme events are consistent evidence of climate change effect on lakes. In this study, we analyzed multiannual variability, determined long-term trends and detected changes in the frequency of extreme events in the surface water temperature (LSWT) of Lake Peipsi (Estonia/Russia) for nearly seven decades (1950-2018) and aimed to trace how the LSWT responded to the climate change. Dynamic water temperature parameters were calculated using the smoothed water temperature curve fitted to daily water temperatures. Our results showed that, although the average LSWT did not increase significantly on an annual basis since 1950 it rose rapidly in the winter season during the last decade (∼ +0.5 °C). Ice formation exhibited a marked (∼15 days) delay since 2007 resulting in a longer open water period. Extreme LSWT events did not occur more frequently. We noticed however significant fluctuating in winter LSWT in time series, starting from 2007 and also causing an increase in stochasticity. The consequences of the on-going winter warming and changes of ice cover phenology are expected to be crucial for Lake Peipsi ecosystem functioning and impact on lake biota, especially temperature-sensitive native fishes. 相似文献
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The major sudden stratospheric warming (SSW) events of 2003–04 and 2005–06 are considered to investigate changes in equatorial convection due to circulation changes associated with the SSW events. It is observed that the SSW events are accompanied by a considerable decrease in Outgoing Longwave Radiation (OLR), a proxy for tropical convection, over equatorial latitudes (15°N–15°S) in the Indonesian sector (90°E–150°E). However, unlike noted by earlier observations, the zonal mean OLR does not show any notable relationship with the SSW events. It can be explained from the latitude–longitude map of potential vorticity (PV) at 100 hPa, which shows a tongue of high PV emanating from high latitudes towards equator and converges in the longitude band of 90°E–150°E on the day of peak warming at 1 hPa in the case of 2003–04 and 10 hPa in the case of 2005–06. The latitude-height map of Eliassen–Palm (EP) vector and its divergence show convergence of EP flux in the upper troposphere at latitudes even lower than 20°N on these days. Further, vertical winds computed from the convergence of momentum flux are upward indicating convective activity at low-latitudes and downward at mid-latitudes. 相似文献
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S. Sridharan K. Raghunath S. Sathishkumar D. Nath 《Journal of Atmospheric and Solar》2010,72(14-15):1139-1146
Rayleigh lidar observations at Gadanki (13.5°N, 79.2°E) show an enhancement of the nightly mean temperature by 10–15 K at altitudes 70–80 km and of gravity wave potential energy at 60–70 km during the 2009 major stratospheric warming event. An enhanced quasi-16-day wave activity is observed at 50–70 km in the wavelet spectrum of TIMED–SABER temperatures, possibly due to the absence of a critical level in the low-latitude stratosphere because of less westward winds caused by this warming event. The observed low-latitude mesospheric warming could be due to wave breaking, as waves are damped at 80 km. 相似文献
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Raquel Somavilla Cabrillo Cesar González-Pola Manuel Ruiz-Villarreal Alicia Lavín Montero 《Ocean Dynamics》2011,61(9):1215-1235
Mixed layer depth (MLD) variability from seasonal to decadal time scales in the Bay of Biscay is studied in this work. A hydrographic
time series running since 1991 in the study area, a climatology of the upper layer vertical structure based on the topology
of this temperature profile time series and a one-dimensional water column model have been used for this purpose. The prevailing
factors driving MLD variability have been determined with detail, and agreement with observations is achieved. Tests carried
out to investigate climatological profile skill to reproduce the upper layer temporal evolution have demonstrated its ability
to simulate variability at seasonal time scales and reproduce the most conspicuous events observed. This has enabled us to
carry out a reconstruction of the MLD variability for the last 60 years in the study area. Favourable sequence of intense
mixing events explains interannual differences and cases of extraordinary deepening of winter mixed layer. The negative phase
of the Eastern Atlantic pattern seems to determine important interannual variability through intense episodes of cooling and
mixing as in winter 2005 in the Bay of Biscay. Low-frequency variability is also observed. A very striking and unexpected
shallower winter MLD during the 1970s and 1980s than those observed from 1995 has been found. Simulation results support this
counter-intuitive outcome of shallower winter mixed layers concurrent with generalized upper water warming trends reported
on several occasions for the area. The long-term trends in MLD seem related with decadal variability in the North Atlantic
Oscillation, being in phase and opposition with other deepening-shallowing cycles found from subtropical-to-subpolar areas
in the North Atlantic. 相似文献
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The most reliable pattern of climate changes is obtained using data of instrumental observations at the network of meteorological
stations. However, the series of such data have short timescales (about 150 years). Indirect data from natural archives make
it possible to judge specific features of climate changes in the more distant past. In contrast to indirect methods, when
data are related to temperature through statistical correlations with air temperature, the borehole geothermal method makes
it possible to directly determine the surface air temperature. The reconstructions of the temperature obtained using different
indirect data for the Northern Hemisphere have been compared with the surface air temperature reconstructions based on the
data of borehole thermometry and solar activity variations, and the possibilities of using the method in order to reconstruct
long-term trends in climate changes have been indicated. 相似文献
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The most reliable pattern of climate changes is obtained using data of instrumental observations at the network of meteorological stations. However, the series of such data have short timescales (about 150 years). Indirect data from natural archives make it possible to judge specific features of climate changes in the more distant past. In contrast to indirect methods, when data are related to temperature through statistical correlations with air temperature, the borehole geothermal method makes it possible to directly determine the surface air temperature. The reconstructions of the temperature obtained using different indirect data for the Northern Hemisphere have been compared with the surface air temperature reconstructions based on the data of borehole thermometry and solar activity variations, and the possibilities of using the method in order to reconstruct long-term trends in climate changes have been indicated. 相似文献