The Role of the Tropically Excited Arctic Warming Mechanism on the Warm Arctic Cold Continent Surface Air Temperature Trend Pattern

Abstract. The Last Interglacial period (129–116 ka BP) is characterized by a strong orbital forcing which leads to a different seasonal and latitudinal distribution of insolation compared to the pre-industrial period. In particular, these changes amplify the seasonality of the insolation in the high latitudes of the northern hemisphere. Here, we investigate the Arctic climate response to this forcing by comparing the CMIP6 lig127k and pi-Control simulations performed with the IPSL-CM6A-LR model. Using an energy budget framework, we analyse the interactions between the atmosphere, ocean, sea ice and continents. In summer, the insolation anomaly reaches its maximum and causes a near-surface air temperature rise of 3.2 °C over the Arctic region. This warming is primarily due to a strong positive surface downwelling shortwave radiation anomaly over continental surfaces, followed by large heat transfers from the continents back to the atmosphere. The surface layers of the Arctic Ocean also receives more energy, but in smaller quantity than the continents due to a cloud negative feedback. Furthermore, while heat exchanges from the continental surfaces towards the atmosphere are strengthened, the ocean absorbs and stores the heat excess due to a decline in sea ice cover. However, the maximum near-surface air temperature anomaly does not peak in summer like insolation, but occurs in autumn with a temperature increase of 4.0 °C relative to the pre-industrial period. This strong warming is driven by a positive anomaly of longwave radiations over the Arctic ocean enhanced by a positive cloud feedback. It is also favoured by the summer and autumn Arctic sea ice retreat (−1.9 × 106 and −3.4 × 106 km2 respectively), which exposes the warm oceanic surface and allows heat stored by the ocean in summer and water vapour to be released. This study highlights the crucial role of the sea ice cover variations, the Arctic ocean, as well as changes in polar clouds optical properties on the Last Interglacial Arctic warming.

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The role of internal variability in climate change projections of North American surface air temperature and temperature extremes in CanESM2 large ensemble simulations

10.5194/egusphere-egu2020-5854 ◽

2020 ◽

Author(s):

Bin Yu ◽

Guilong Li ◽

Shangfeng Chen ◽

Hai Lin

Keyword(s):

Climate Change ◽

Air Temperature ◽

North American ◽

Surface Air Temperature ◽

Internal Variability ◽

Temperature Extremes ◽

Large Ensemble ◽

Climate Simulations ◽

Ensemble Mean

<p>Recent studies indicated that the internal climate variability plays an important role in various aspects of projected climate changes on regional and local scales. Here we present results of the spreads in projected trends of wintertime North American surface air temperature and extremes indices of warm and cold days over the next half-century, by analyzing a 50-member large ensemble of climate simulations conducted with CanESM2. CanESM2 simulations confirm the important role of internal variability in projected surface temperature trends as demonstrated in previous studies. Yet the spread in North American warming trends in CanESM2 is generally smaller than those obtained from CCSM3 and ECHAM5 large ensemble simulations. Despite this, large spreads in the climate means as well as climate change trends of North American temperature extremes are apparent in CanESM2, especially in the projected cold day trends. The ensemble mean of forced climate simulations reveals high risks of warm days over the western coast and north Canada, as well as a weakening belt of cold days extending from Alaska to the northeast US. The individual ensemble members differ from the ensemble mean mainly in magnitude of the warm day trends, but depart from the ensemble mean in conspicuous ways, including spatial pattern and magnitude, of the cold day trends. The signal-to-noise ratio pattern of the warm day trend resembles that of the surface air temperature trend; with stronger signals over north Canada, Alaska, and the southwestern US than the midsection of the continent. The projected cold day patterns reveal strong signals over the southwestern US, north Canada, and the northeastern US. In addition, the internally generated components of temperature and temperature extreme trends exhibit spatial coherences over North America, and are comparable to the externally forced trends. The large-scale atmospheric circulation-induced temperature variability influences these trends. Overall, our results suggest that climate change trends of North American temperature extremes are likely very uncertain and need to be applied with caution.</p>

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Role of the warming trend in global land surface air temperature variations

Science China Earth Sciences ◽

10.1007/s11430-020-9775-8 ◽

2021 ◽

Author(s):

Zhiyan Zuo ◽

Dong Xiao ◽

Qiong He

Keyword(s):

Air Temperature ◽

Land Surface ◽

Surface Air Temperature ◽

Warming Trend ◽

Temperature Variations ◽

Global Land ◽

Air Temperature Variations

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On the Possible Link between Tropical Convection and the Northern Hemisphere Arctic Surface Air Temperature Change between 1958 and 2001

Journal of Climate ◽

10.1175/2011jcli4003.1 ◽

2011 ◽

Vol 24 (16) ◽

pp. 4350-4367 ◽

Cited By ~ 98

Author(s):

Sukyoung Lee ◽

Tingting Gong ◽

Nathaniel Johnson ◽

Steven B. Feldstein ◽

David Pollard

Keyword(s):

Arctic Ocean ◽

Interannual Variability ◽

Northern Hemisphere ◽

Air Temperature ◽

Surface Air Temperature ◽

Convective Precipitation ◽

Frequency Of Occurrence ◽

Teleconnection Patterns ◽

Polar Amplification ◽

Trend Pattern

Abstract This study presents mechanisms for the polar amplification of surface air temperature that occurred in the Northern Hemisphere (NH) between the periods of 1958–77 (P1) and 1982–2001 (P2). Using European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) reanalysis data, it is found that over the ice-covered Arctic Ocean, the winter surface warming arises from dynamic warming (stationary eddy heat flux and adiabatic warming). Over the ice-free Arctic Ocean between the Greenland and the Barents Seas, downward infrared radiative (IR) flux is found to dominate the warming. To investigate whether the difference in the flow between P1 and P2 is due to changes in the frequency of occurrence of a small number of teleconnection patterns, a coupled self-organizing map (SOM) analysis of the 250-hPa streamfunction and tropical convective precipitation is performed. The latter field was specified to lead the former by 5 days. The results of the analysis showed that the P2 − P1 trend arises from a decrease in the frequency of negative phase PNA-like and circumglobal streamfunction patterns and a corresponding increase in the frequency of positive PNA-like and circumglobal streamfunction patterns. The occurrence of the two strong 1982–83 and 1997–98 El Niño events also contributes toward this trend. The corresponding trend in the convective precipitation is from below average to above average values in the tropical Indo-western Pacific region. Each of the above patterns was found to have an e-folding time scale from 6 to 8 days, which implies that the P2 − P1 trend can be understood as arising from the change in the frequency of occurrence of teleconnection patterns that fluctuate on intraseasonal time scales. The link between intraseasonal and interannual variability was further examined by linearly regressing various quantities against trend patterns with interannual variability subtracted. It was found that enhanced convective precipitation is followed 3–6 days later by the occurrence of the P2 − P1 circulation trend pattern, and then 1–2 days later by the corresponding trend pattern in the downward IR flux. This finding suggests that an increased frequency of the above sequence of events, which occurs on intraseasonal time scales, can account for the NH winter polar amplification of the surface air temperature via increased dynamic warming and downward IR flux.

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Australia's Air Temperature Trend Reviewed

Journal of Southern Hemisphere Earth System Science ◽

10.1071/es16019 ◽

2016 ◽

Vol 66 (3) ◽

pp. 270

Author(s):

Gregory P. Ayers

Keyword(s):

Time Series ◽

Air Temperature ◽

Temperature Anomaly ◽

Surface Air Temperature ◽

Temperature Trend ◽

Temperature Record ◽

Trend Estimation ◽

Australian Region ◽

Anthropogenic Contribution

The hypothesis of an artificially exaggerated temperature trend in the Australian continental surface air temperature record is tested via comparison with four other records of temperature measured in the Australian region. The trends extracted from all five records are consistent, so the hypothesis of bias in the Bureau of Meteorology’s Australian surface air temperature record cannot be sustained and is rejected. Using three different methods of trend estimation applied to five temperature anomaly time series, the anthropogenic contribution to warming of the Australian region since 1950 is determined to have occurred at a rate of 0.12 ± 0.02K per decade, which translates to a total anthropogenic warming contribution of 0.78 ± 0.13K over the period 1950 to 2015.

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Comparison of Early Twentieth Century Arctic Warming and Contemporary Arctic Warming in the light of daily and sub-daily data

Journal of Climate ◽

10.1175/jcli-d-21-0162.1 ◽

2022 ◽

pp. 1-59

Keyword(s):

Twentieth Century ◽

Air Temperature ◽

Diurnal Temperature Range ◽

Surface Air Temperature ◽

The Arctic ◽

Arctic Warming ◽

Diurnal Temperature ◽

Temperature Range ◽

Early Twentieth Century ◽

Daily Data

Abstract A review of many studies published since the late 1920s reveals that the main driving mechanisms responsible for the Early Twentieth Century Arctic Warming (ETCAW) are not fully recognized. The main obstacle seems to be our limited knowledge about the climate of this period and some forcings. A deeper knowledge based on greater spatial and temporal resolution data is needed. The article provides new (or improved) knowledge about surface air temperature (SAT) conditions (including their extreme states) in the Arctic during the ETCAW. Daily and sub-daily data have been used (mean daily air temperature, maximum and minimum daily temperature, and diurnal temperature range). These were taken from ten individual years (selected from the period 1934–50) for six meteorological stations representing parts of five Arctic climatic regions. Standard SAT characteristics were analyzed (monthly, seasonal, and yearly means), as were rarely investigated aspects of SAT characteristics (e.g., number of characteristic days; day-to-day temperature variability; and onset, end, and duration of thermal seasons). The results were compared with analogical calculations done for data taken from the Contemporary Arctic Warming (CAW) period (2007–16). The Arctic experienced warming between the ETCAW and the CAW. The magnitude of warming was greatest in the Pacific (2.7 °C) and Canadian Arctic (1.9 °C) regions. A shortening of winter and lengthening of summer were registered. Furthermore, the climate was also a little more continental (except the Russian Arctic) and less stable (greater day-to-day variability and diurnal temperature range) during the ETCAW than during the CAW.

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