Strengthened Connections Between Arctic Sea Ice and Thermal Conditions Over the Tibetan Plateau in May After the 2000s

Abstract

The thermal conditions of the Tibetan Plateau (TP) during spring are significantly related to climate changes on regional and hemispheric scales. The surface skin temperature over the TP in May exhibits an increasing trend over the northern and central-western regions since the 2000s. This heterogeneous distribution has a strengthened relationship with changes in Arctic sea-ice concentration (SIC) over the Barents-Kara Seas after 2001, showing a significant negative correlation. Along with the dramatic SIC variations after 2001, there is a mid-latitude wave train akin to the Circumglobal Teleconnection (CGT), accompanied by an anomalous anticyclone around the TP. On the one hand, the high-latitude energy associated with the SIC changes spreads through the Barents-Kara Seas toward the southeast, causing intensified westerly winds over the West Siberian Plain. The anomalies imply a poleward subtropical jet, which affects the anticyclonic anomaly over the TP, situated south of the jet axis, through dynamic processes. On the other hand, the cyclonic anomalies at high latitudes, linked with reduced SIC, inhibit snow melting and bring lower soil moisture content. Consequently, increased meridional temperature gradients and background baroclinicity cover the West Siberian Plain and regions encompassing the Black Sea and the Mediterranean, demonstrating the impacts of SIC variations on mid-latitude Rossby waves. Responses to the anomalous anticyclone over the TP, heightened downward motions favor enhanced adiabatic heating and result in reduced cloud cover, further causing decreased snow depth. Influenced by snow-albedo and cloud-radiation feedback, the net downward short-wave radiation increases and leads to the TP warming after 2001.

Key Points

• The relationship in May between the TP warming and sea ice variations over the Barents-Kara Seas strengthens after 2001

• Along with sea ice changes after 2001, associated thermal-dynamic processes affect the formation and intensity of the CGT-like wave

• An anticyclone over the TP occurs with sea ice changes after 2001, the snow-albedo and cloud-radiation feedbacks help TP warming in May

Plain Language Summary

Both the Tibetan Plateau (TP) and the Arctic have undergone accelerated warming in recent years, this study identifies a strengthened relationship in May between the thermal conditions over the TP and changes in sea-ice concentration (SIC) within the Barents-Kara Seas after 2001. Corresponded changes in atmospheric circulations to reduced SIC exhibit an evident mid-latitude wave train akin to the Circumglobal Teleconnection (CGT), and show a significant anticyclonic anomaly around the TP. The potential linkages are discussed from the thermal-dynamic perspectives. From one side, the anomalous cyclone, centered at the Central Siberian Plateau and associated with high-latitude energy propagation, induces intensified westerly winds from the West Siberian Plain to the northern TP. The anomalies contribute to the poleward subtropical jet and influence the anticyclone over the TP through dynamic processes. From the other side, the land-atmosphere interactions over high latitudes lead to increased meridional temperature gradients over the West Siberian Plain and regions spanning the Black Sea and the Mediterranean, which affect the formation and intensity of the CGT-like pattern. Alongside the significant anticyclone dominating the TP, the combined effects of snow-albedo and cloud-radiation feedback ultimately contribute to the TP warming in May after 2001.