scholarly journals Validation of reanalysis Southern Ocean atmosphere trends using sea ice data

2020 ◽  
Author(s):  
William R. Hobbs ◽  
Andrew R. Klekociuk ◽  
Yuhang Pan
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Surface Temperature ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Heat Fluxes ◽  
Surface Energy Budget ◽  
Close Coupling ◽  
In Situ Data ◽  
Temperature Trends

Abstract. Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in-situ data, and especially the Antarctic. A comparison of 8 different reanalysis products shows large differences sea level pressure and surface air temperature trends over the high latitude Southern Ocean, with implications for studies of the atmosphere's role in driving ocean-sea ice changes. In this study, we use the established close coupling between sea ice cover and surface temperature to evaluate these reanalysis trends using the independent, 30-year sea ice record from 1980–2010. We demonstrate that sea ice trends are a reliable validation tool for most months of the year, although the sea ice-surface temperature coupling is weakest in summer when the surface energy budget is dominated by atmosphere-to-ocean heat fluxes. Based on our analysis, we find that surface air temperature trends in JRA55 are most consistent with satellite-observed sea ice trends over the polar waters of the Southern Ocean.

scholarly journals Validation of reanalysis Southern Ocean atmosphere trends using sea ice data

2020 ◽  
Vol 20 (23) ◽  
pp. 14757-14768
Author(s):  
William R. Hobbs ◽  
Andrew R. Klekociuk ◽  
Yuhang Pan
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Surface Temperature ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Heat Fluxes ◽  
Surface Energy Budget ◽  
Close Coupling ◽  
In Situ Data ◽  
Temperature Trends

Abstract. Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in situ data, and especially the Antarctic. A comparison of eight different reanalysis products shows large differences in sea level pressure and surface air temperature trends over the high-latitude Southern Ocean, with implications for studies of the atmosphere's role in driving ocean–sea ice changes. In this study, we use the established close coupling between sea ice cover and surface temperature to evaluate these reanalysis trends using the independent, 30-year sea ice record from 1980 to 2010. We demonstrate that sea ice trends are a reliable validation tool for most months of the year, although the sea ice–surface temperature coupling is weakest in summer when the surface energy budget is dominated by atmosphere-to-ocean heat fluxes. Based on our analysis, we find that surface air temperature trends in JRA55 are most consistent with satellite-observed sea ice trends over the polar waters of the Southern Ocean.

scholarly journals An updated evaluation of the global mean land surface air temperature and surface temperature trends based on CLSAT and CMST

2021 ◽  
Vol 56 (1-2) ◽  
pp. 635-650 ◽  
Author(s):  
Qingxiang Li ◽  
Wenbin Sun ◽  
Xiang Yun ◽  
Boyin Huang ◽  
Wenjie Dong ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface ◽  
Surface Air Temperature ◽  
Temperature Trends ◽  
Global Mean

scholarly journals Changes of Variability in Response to Increasing Greenhouse Gases. Part I: Temperature

2007 ◽  
Vol 20 (21) ◽  
pp. 5455-5467 ◽  
Author(s):  
R. J. Stouffer ◽  
R. T. Wetherald
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Annual Data ◽  
Tropospheric Temperature ◽  
High Latitudes ◽  
Near Surface ◽  
Temperature Variance ◽  
General Reduction

Abstract This study documents the temperature variance change in two different versions of a coupled ocean–atmosphere general circulation model forced with estimates of future increases of greenhouse gas (GHG) and aerosol concentrations. The variance changes are examined using an ensemble of 8 transient integrations for the older model version and 10 transient integrations for the newer one. Monthly and annual data are used to compute the mean and variance changes. Emphasis is placed upon computing and analyzing the variance changes for the middle of the twenty-first century and compared with those found in a control integration. The large-scale variance of lower-tropospheric temperature (including surface air temperature) generally decreases in high latitudes particularly during fall due to a delayed onset of sea ice as the climate warms. Sea ice acts to insolate the atmosphere from the much larger heat capacity of the ocean. Therefore, the near-surface temperature variance tends to be larger over the sea ice–covered regions, than the nearby ice-free regions. The near-surface temperature variance also decreases during the winter and spring due to a general reduction in the extent of sea ice during winter and spring. Changes in storminess were also examined and were found to have relatively little effect upon the reduction of temperature variance. Generally small changes of surface air temperature variance occurred in low and midlatitudes over both land and oceanic areas year-round. An exception to this was a general reduction of variance in the equatorial Pacific Ocean for the newer model. Small increases in the surface air temperature variance occur in mid- to high latitudes during the summer months, suggesting the possibility of more frequent and longer-lasting heat waves in response to increasing GHGs.

scholarly journals Sea Ice–Ocean Feedbacks in the Antarctic Shelf Seas

2019 ◽  
Vol 49 (9) ◽  
pp. 2423-2446 ◽  
Author(s):  
R. C. Frew ◽  
D. L. Feltham ◽  
P. R. Holland ◽  
A. A. Petty
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Mixed Layer ◽  
Surface Air Temperature ◽  
Weddell Sea ◽  
Surface Energy Budget ◽  
Atmospheric Conditions ◽  
Ocean Mixed Layer ◽  
Amundsen Sea ◽  
The Antarctic

AbstractObserved changes in Antarctic sea ice are poorly understood, in part due to the complexity of its interactions with the atmosphere and ocean. A highly simplified, coupled sea ice–ocean mixed layer model has been developed to investigate the importance of sea ice–ocean feedbacks on the evolution of sea ice and the ocean mixed layer in two contrasting regions of the Antarctic continental shelf ocean: the Amundsen Sea, which has warm shelf waters, and the Weddell Sea, which has cold and saline shelf waters. Modeling studies where we deny the feedback response to surface air temperature perturbations show the importance of feedbacks on the mixed layer and ice cover in the Weddell Sea to be smaller than the sensitivity to surface atmospheric conditions. In the Amundsen Sea the effect of surface air temperature perturbations on the sea ice are opposed by changes in the entrainment of warm deep waters into the mixed layer. The net impact depends on the relative balance between changes in sea ice growth driven by surface perturbations and basal-driven melting. The changes in the entrainment of warm water in the Amundsen Sea were found to have a much larger impact on the ice volume than perturbations in the surface energy budget. This creates a net negative ice albedo feedback in the Amundsen Sea, reversing the sign of this typically positive feedback mechanism.

Dominant Covarying Climate Signals in the Southern Ocean and Antarctic Sea Ice Influence during the Last Three Decades

2017 ◽  
Vol 30 (8) ◽  
pp. 3055-3072 ◽  
Author(s):  
D. Cerrone ◽  
G. Fusco ◽  
I. Simmonds ◽  
G. Aulicino ◽  
G. Budillon
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Surface Air Temperature ◽  
Southern Annular Mode ◽  
Heat Fluxes ◽  
Sea Ice Concentration ◽  
Antarctic Sea Ice ◽  
Zonal Wavenumber ◽  
Temporal Variance ◽  
Climate Signals

A composite dataset (comprising geopotential height, sea surface temperature, zonal and meridional surface winds, precipitation, cloud cover, surface air temperature, latent plus sensible heat fluxes, and sea ice concentration) has been investigated with the aim of revealing the dominant time scales of variability from 1982 to 2013. Three covarying climate signals associated with variations in the sea ice distribution around Antarctica have been detected through the application of the multiple-taper method with singular value decomposition (MTM-SVD). Features of the established patterns of variation over the Southern Hemisphere extratropics have been identified in each of these three climate signals in the form of coupled or individual oscillations. The climate patterns considered here are the southern annular mode (SAM), the Pacific–South American (PSA) teleconnection, the semiannual oscillation (SAO), and the zonal wavenumber-3 (ZW3) mode. It is shown that most of the sea ice temporal variance is concentrated at the quasi-triennial scale resulting from the constructive superposition of the PSA and ZW3 patterns. In addition, the combination of the SAM and SAO patterns is found to promote the interannual sea ice variations underlying a general change in the Southern Ocean atmospheric and oceanic circulations. These two modes of variability are also found to be consistent with the occurrence of the positive SAM/negative PSA (SAM+/PSA−) or negative SAM/positive PSA (SAM−/PSA+) combinations, which could have favored the cooling of the sub-Antarctic region and important changes in the Antarctic sea ice distribution since 2000.

scholarly journals Seasonally changing contribution of sea ice and snow cover to uncertainty in multi-decadal Eurasian surface air temperature trends based on CESM simulations

2021 ◽  
Author(s):  
Zhaomin Ding ◽  
Renguang Wu
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Western Siberia ◽  
Russian Far East ◽  
Far East ◽  
Surface Air Temperature ◽  
The Caspian Sea ◽  
Sea Ice Concentration ◽  
Northern Siberia ◽  
The Impact

AbstractThis study investigates the impact of sea ice and snow changes on surface air temperature (SAT) trends on the multidecadal time scale over the mid- and high-latitudes of Eurasia during boreal autumn, winter and spring based on a 30-member ensemble simulations of the Community Earth System Model (CESM). A dynamical adjustment method is used to remove the internal component of circulation-induced SAT trends. The leading mode of dynamically adjusted SAT trends is featured by same-sign anomalies extending from northern Europe to central Siberia and to the Russian Far East, respectively, during boreal spring and autumn, and confined to western Siberia during winter. The internally generated component of sea ice concentration trends over the Barents-Kara Seas contributes to the differences in the thermodynamic component of internal SAT trends across the ensemble over adjacent northern Siberia during all the three seasons. The sea ice effect is largest in autumn and smallest in winter. Eurasian snow changes contribute to the spread in dynamically adjusted SAT trends as well around the periphery of snow covered region by modulating surface heat flux changes. The snow effect is identified over northeast Europe-western Siberia in autumn, north of the Caspian Sea in winter, and over eastern Europe-northern Siberia in spring. The effects of sea ice and snow on the SAT trends are realized mainly by modulating upward shortwave and longwave radiation fluxes.

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