Mechanism underlying the correlation between the warming-wetting of the Qinghai-Tibet Plateau and atmospheric energy changes in high-impact oceanic areas

Abstract

The powerful thermal driving force of the Qinghai-Tibet Plateau (QTP) exerts a significant influence on weather, climate, and environmental processes in Asia and across the globe. This paper investigates the causes of climate change on the QTP from the perspective of global atmospheric energy transport and water cycle. During summer, a “hollow energy pool” has been discovered in the troposphere, with its energy center located above the QTP, the “Asian water tower”. Our study indicates that the QTP serves as a critical “window” for the global transport of water vapor and energy. Since 1991, the total atmospheric energy (TAE) and precipitation in the warming-wetting region of the QTP (central and northern plateau) have exhibited interdecadal growth. Furthermore, the TAE of the plateau is closely linked to the TAE and water vapor of oceans at mid-low latitudes, and even in the southern hemisphere, the increased precipitation in the warming-wetting region of the plateau has been mainly regulated by the atmospheric energy and water vapor transport structures over the equatorial western Pacific, southwestern Pacific, and southern Indian Ocean, we further reveal the energy transport channel from the warming oceanic areas of the southern and northern hemispheres to the QTP. This study deepens the novel understanding of atmospheric energy accompanying water vapor transport in the southern and northern hemispheres, which is of significant importance for understanding the responses of energy and water cycle in the warming-wetting of the QTP and global climate change.

Introduction

The Qinghai-Tibetan plateau (QTP), known as the “Roof of the World”, is particularly susceptible to the effects of global warming, and has an essential feedback effect on the Asian climate system and even the global climate system1,2.

The energy and water cycling mechanism among the QTP-land-ocean has long been of great concern3. As one of the most sensitive regions responding to global climate change, the water resource changes in the QTP in recent decades have shown obvious spatial variations4,5,6,7. For example, the rate of glacier retreat decreases progressively from the Himalayas to the Pamir Plateau8,9,10. Lake expansion mainly occurs in the interior of the QTP, while the Himalayan region exhibits more lake shrinkage11,12. The overall increase in precipitation shows a trend of decrease in the south and increase in the north, with significant increases mainly occurring in the central-northern part of the QTP13,14,15,16,17,18. In previous studies, the atmospheric heat source was characterized by the researchers to represent the thermal role of the QTP. Driven by this heat source, the QTP functions as a potent “heat pump” and continuously attracts warm and humid vapor from the mid-to-low-latitude oceans19,20, which builds up the structure of the trans-hemispheric atmospheric moisture cycle.

The ocean and atmosphere are essential components of the climate system. While solar radiation is the ultimate energy source driving climate change and atmospheric motion, the primary energy directly driving atmospheric circulation comes mainly from the ocean21,22. Due to the spherical nature of the Earth, there is an energy surplus in low latitudes, forming energy source regions, while high latitudes experience energy deficits, forming energy sinks. The atmosphere acts as one of the transporters, transferring energy from low to mid-to-high latitudes. Jian et al.23 provided the first explanation of the driving role of low-latitude ocean processes in climate evolution from an energy perspective, revealing that the heat from the Indo-Pacific Warm Pool can regulate water vapor transport between the Asian continent and the Pacific Ocean. He et al.24 argued that because of global warming, more than 90% of the heat energy has been absorbed by the oceans, and that the heat energy, most of which has been “hidden” in the Southern Ocean, has been accumulating year after year25,26,27.

If the atmosphere is regarded as a heat engine, the atmospheric heat source over the QTP provides energy to the heat engine. The atmospheric energy of the QTP determines the operational state of this heat engine, while the difference in atmospheric energy between the QTP and the external world determines the efficiency of this heat engine28. In previous studies on the thermodynamics of the QTP, there has been a lack of systematic analysis of the distribution and variation of atmospheric energy over the QTP, with only a small amount of work involving atmospheric energy. Atmospheric energy is key to studying the thermodynamics of the QTP. What are the distribution characteristics of the atmospheric energy over the QTP? How does the atmospheric energy evolve under the background of climate change? What impact will the change have on the climate of the region? Does the atmospheric energy over the QTP play an important role in the trans-hemispheric water vapor transport? All these questions are not well addressed up till now.

Although it has been recognized that tropical oceans are an energy source and provide energy for atmospheric circulation, the study on how they affect the global circulation system, especially the mid-to-high latitude circulation system, remains limited. With global warming, the sea surface temperature (SST) tends to increase. So how will the atmospheric energy over the ocean change accordingly? Since low-latitude oceans serve as energy source regions, how does the atmospheric energy over the low-latitude oceans transport to mid-to-high latitude regions through circulation? And what impact will the transport have on the climate of mid-to-high latitude regions? Therefore, by using a new physical quantity-total atmospheric energy (TAE), this paper attempts to investigate from a new perspective, namely global atmospheric energy and water cycle, to elucidate the mechanism of atmospheric energy transport from the warming regions of the Southern Hemisphere oceans to the climate-sensitive area of the Northern Hemisphere, particularly the “QTP”, which can more profoundly uncover the impact of the atmospheric energy over the ocean on the climate of East Asia, and to provide a basis for the thorough understanding of the overall characteristics of prolonged global climate change from the perspective of energetics.

Results

TAE structure characteristics over the QTP

Figure 1a shows that the global TAE in summer exhibits a distribution pattern of decreasing from low latitude to high latitude. Notably, the total atmospheric energy of the QTP (QTPE) is significantly higher than that in other regions at the same latitude, and even higher than in the equatorial region, forming a high-value closure center over the upper and middle levels of the troposphere, and the closure center extends southward to the Bay of Bengal, India, and northern Southeast Asia.