Influence Of Dominant Interannual And Decadal Sea Surface Temperature Modes On The Global Surface Temperature

Global temperature change will lead to drastic change of the earth system,which is one of the fundamental questions in climate science and concerned by countries and governments around the world.Based on multiple observations and reanalysis datasets and also the simulations from multi-models,the present work investigates the impacts of decadal and interannual dominate sea surface temperature(SST)modes on the global and the Arctic surface temperature respectively.Firstly,we investigate the statistical relationships of the multi-decadal global warming rate and Arctic winter air temperature variability with the dominate SST modes.Considering the complexity of ENSO events,we then explore the different responses of global and Arctic surface temperature to the two types of ENSO.Main conclusions are summerized as follows:(1)A robust statistical relationship between the global warming rate variations and Atlantic Multidecadal Oscillation(AMO)variability.The correlation between AMO and the global warming rate is maximized at ?10-20 years lead-time based on the available observations.In contrast,such a relation between global warming rate and the Interdecadal Pacific Oscillation(IPO)is far less coherent,showing negative correlation before the 1920 s and positive correlation after that.Similar statistical relationships between global warming rate variations and the AMO can also be seen in almost all of the pre-industrial control simulations form the 31 Coupled Models Inter-comparison Project Phase 5(CMIP5)models.While there is no consistent relationships between IPO and global warming rate in these models.Further,a targeted model experiment is conducted to demonstrate the dominant control of the AMO on the unforced fraction of the global warming rate.(2)The change of the decadal relationship between the IPO and the surface air temperature over Greenland and its surrounding areas.IPO shows significant positive correlation with the winter surface air temperature(SAT)of Greenland and its surrounding regions before 1976 and such relation becomes insignificant after that.Compared with the IPO related atmospheric circulation before 1976,the situation after 1976 changed a lot,especially over the North Atlantic.The change of the coupled mode between tropical pacific SST and the upper-level circulation over North Hemisphere may be responsible for this shift.During 1924-1976,the IPO-liked SST pattern is coupled with the upper circulation over the Greenland.The asscoiated SST anomaly can enhance the positive geopotential height over the key region through poleward Rossby wave and lead to regional warming.During 1977-2012,the circulation over the Greenland region is associated with the cold SST over the tropical central pacific.In the whole period,the AMO shows close and stable relationship with the SAT over Greenland and its surrounding regions.(4)Different global surface temperature responses to the two types of ENSO.The difference of global zonal mean surface temperature responses to the two types ENSO is located in the midd-high latitude over North Hemisphere during later winter and early spring(February-March).During the EP-El Ni(?)o,the high latitude(60°N-85°N)tend to be colder and the middle latitude(35°N-60°N)become warmer,manifesting as a meridional dipole.While the temperature responses to the CP-El Ni(?)o and two type of La Ni(?)a are opposite to that of the EP-El Ni(?)o.The meridional SAT dipole is dominated by the SAT variation over Eurasia.The sea level pressure(SLP)and low-level wind response to the EP-El Ni(?)o is different from the other events,which can warm/cold this area through temperature advection.These low-level circulations are related with the different teleconnections excited by two types of ENSO events.Different convections in two types ENSO,especially the strong convection over the tropical Eastern Pacific during EP-El Ni(?)o may lead to different teleconnections and result in different responses of SAT.The results of AMIP from ACCESS1.0 further confirm the conclusions.(5)Different responses of Arctic surface air temperature to the two ENSO types.Two warming fast regions over the Arctic respond to the two types of ENSO during February.EP ENSO events are accompanied by statistically significant composite SAT anomalies over the Barents-Kara Seas(negative SAT anomalies during El Ni(?)o and positive SAT anomalies during La Ni(?)a),while CP ENSO events are accompanied by statistically significant SAT anomalies over northeastern Canada and Greenland(positive SAT anomalies during El Ni(?)o and negative SAT anomalies during La Ni(?)a).The different Arctic SAT responses to the two ENSO types can be attributed to different large-scale teleconnection patterns via Rossby wave propagations.Different regional circulation can warm/cool the key regions and then enhanced through the vapor-cloud-radiation feedback.Moreover,a series of atmospheric general circulation model experiments with GFDL AM2.1 are able to reproduce the general observed features in the Arctic in response to prescribed tropical ENSO SST anomaly forcing.