Shang-Ping Xie

• Ph.D.
• Professor at University of California, San Diego

Tropical instability waves (TIWs) are a prominent mesoscale feature observed in satellite sea surface temperature (SST) fields over the equatorial Pacific Ocean. This study develops an SST conservation model to estimate the meridional velocities associated with TIWs (υ′). The model achieves a correlation coefficient of around 0.8 in υ′ against moor...

Extratropical energy forcing exerts a strong influence on tropical sea surface temperature (SST) via both oceanic and atmospheric teleconnection pathways. While recent studies have emphasized the role that coupled surface ocean-atmospheric feedbacks play in communicating subtropical temperature anomalies to the tropical Pacific, details of the subs...

Global climate models generally project a robust decline in Antarctic sea ice (ASI) under increased atmospheric carbon dioxide (CO2) while an ASI expansion has been observed over the recent four decades. Motivated by the apparent model‐observation discrepancy, this study investigates the influences of ASI change on global warming pattern by exploit...

Climate models vary widely in projections of 21st century global warming and projections of the Atlantic Meridional Overturning Circulation (AMOC). However, the extent to which this uncertainty in AMOC contributes to uncertainty in warming has not yet been quantified. To investigate this, we perform climate model experiments that increase CO2 conce...

While the tropical Pacific teleconnection to North America has been studied extensively, the impact of the Indian Ocean on North American climate has received less attention. Here, through observational analysis and hierarchy atmospheric model simulations with different complexity, we find that the Indian Ocean plays a crucial role in North America...

Tropical convection plays a critical role in modulating the global climate by influencing climate variability. However, its future projection under climate mitigation scenarios remains uncertain. Here, we found that while the relationship between precipitation intensity and upward motion remains constant regardless of changing CO2 concentrations, t...

Over the subtropical Northeast Pacific (NEP), highly reflective low clouds interact with underlying sea-surface temperature (SST) to constitute a local positive feedback. Recent modeling studies showed that, together with wind-evaporation-SST (WES) feedback, the summertime low cloud-SST feedback promotes nonlocal trade wind variations, modulating s...

Deep convection in the Indo-Pacific warm pool is vital in driving global atmospheric overturning circulations. Year-to-year variations in the strength and location of warm pool precipitation can lead to significant local and downstream hydroclimatic impacts, including floods and droughts. While the El Niño-Southern Oscillation (ENSO) is recognized...

The East Asian summer monsoon (EASM) supplies vital rainfall for over one billion people. El Niño-Southern Oscillation (ENSO) markedly affects the EASM, but its impacts are more robust following El Niño than La Niña. Here, we show that this asymmetry arises from the asymmetry in ENSO evolution: though most El Niño events last for one year, La Niña...

A typical El Niño event often results in suppressed tropical cyclone (TC) genesis frequency (TCGF) over the North Atlantic (NA) and a distinct northwest-southeast dipole pattern in TCGF anomaly over the western North Pacific (WNP). The 2023 saw a strong El Niño event but surprisingly active NA and suppressed WNP TC activities. Here, we present that...

Skillful subseasonal forecasts are crucial for various sectors of society but pose a grand scientific challenge. Recently, machine learning-based weather forecasting models outperform the most successful numerical weather predictions generated by the European Centre for Medium-Range Weather Forecasts (ECMWF), but have not yet surpassed conventional...

The El Niño–Southern Oscillation (ENSO) in a warming climate has been studied extensively, but the response beyond 2100 has received little attention. Here, using long-term model simulations, we find that while ENSO variability exhibits diverse changes in the short term, there is a robust reduction in ENSO variability by 2300. Continued warming bey...

Arctic Amplification (AA), the amplified surface warming in the Arctic relative to the globe, is a salient feature of climate change. While the basic physical picture of AA has been depicted, how its degree is determined has not been clearly understood. Here, by deciphering atmospheric heat transport (AHT), we build a two-box energy-balance model o...

Decadal variability in the North Atlantic Ocean impacts regional and global climate, yet changes in internal decadal variability under anthropogenic radiative forcing remain largely unexplored. Here we use the Community Earth System Model 2 Large Ensemble under historical and the Shared Socioeconomic Pathway 3-7.0 future radiative forcing scenarios...

During 2010 to 2020, Northeast Pacific (NEP) sea surface temperature (SST) experienced the warmest decade ever recorded, manifested in several extreme marine heatwaves, referred to as “warm blob” events, which severely affect marine ecosystems and extreme weather along the west coast of North America. While year-to-year internal climate variability...

In July to August 2022, Pakistan suffered historic flooding while record-breaking heatwaves swept southern China, causing severe socioeconomic impacts. Similar extreme events have frequently coincided between two regions during the past 44 years, but the underlying mechanisms remain unclear. Using observations and a suite of model experiments, here...

This study examines the spatial distribution and temporal variations of low‐cloud top over the subtropical northeast Pacific (NEP), using observations from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). A comparison between CALIPSO observations and in‐situ soundings reveals a distinct bimodal distribution of low‐c...

In the boreal spring of 2023, an extreme coastal El Niño struck the coastal regions of Peru and Ecuador, causing devastating rainfalls, flooding, and record dengue outbreaks. Observations and ocean model experiments reveal that northerly alongshore winds and westerly wind anomalies in the eastern equatorial Pacific, initially associated with a reco...

Climate models suffer from longstanding precipitation biases, much of which has been attributed to their atmospheric component owing to unrealistic parameterizations. Here we investigate precipitation biases in 37 Atmospheric Model Intercomparison Project Phase 6 (AMIP6) models, focusing on the Indo‐Pacific region during boreal summer. These models...

A deep winter mixed layer forms north of the Antarctic Circumpolar Current (ACC) in the Indo-Pacific sectors, while the mixed layer depth (MLD) is shallow in the Atlantic. Using observations and a global atmospheric model, this study investigates the contribution of surface buoyancy flux and background stratification to inter-basin MLD variations....

The North Pacific Oscillation (NPO), an important mode of atmospheric variability, is a crucial trigger for the development of El Niño-Southern Oscillation (ENSO) via the seasonal footprinting mechanism. How the NPO effect on ENSO changes in response to greenhouse warming remains unclear, however. Here, using climate model simulations under high-em...

Based on data collected from 14 buoys in the Gulf Stream, this study examines how hourly air–sea turbulent heat fluxes vary on subdaily time scales under different boundary layer stability conditions. The annual mean magnitudes of the subdaily variations in latent and sensible heat fluxes at all stations are 40 and 15 W m ⁻² , respectively. Under n...

Positive feedbacks in climate processes can make it difficult to identify the primary drivers of climate phenomena. Some recent global climate model (GCM) studies address this issue by controlling the wind stress felt by the surface ocean such that the atmosphere and ocean become mechanically decoupled. Most mechanical decoupling studies have chose...

Skillful subseasonal forecasts beyond 2 weeks is critical to various sectors of society but pose a grand scientific challenge. Recently, machine learning based weather forecasting models have made remarkable advancements, outperforming the most successful numerical weather predictions (NWP) generated by the European Centre for Medium-Range Weather...

Exceptionally strong summertime warming occurred over the Mongolian Plateau between 1986 and 2004, at a rate that was three times the average terrestrial warming in the Northern Hemisphere. The physical processes responsible for this extreme warming remain unclear. Here we show that the synchronous phase shift of the Interdecadal Pacific Oscillatio...

Tropical instability waves (TIWs) arise from shear instabilities of equatorial Pacific Ocean currents and are important for the tropical climate and the El Niño–Southern Oscillation. Yet the long-term evolution of TIW activity under climate change remains unclear due to the difficulty in estimating equatorial current velocity. Here we use in situ,...

The discrepancy between the observed lack of surface warming in the eastern equatorial Pacific and climate model projections of an El Niño-like warming pattern confronts the climate research community. While anthropogenic aerosols have been suggested as a cause, the prolonged cooling trend over the equatorial Pacific appears in conflict with Northe...

A scientific revolution was underway in the 1980s treating the ocean and atmosphere as a coupled system. In addition to Bjerknes feedback for El Nino in the equatorial upwelling zone, wind-evaporation-sea surface temperature (WES) feedback was originally proposed to explain the northward-displaced intertropical convergence zone (ITCZ) but broadened...

The El Niño-Southern Oscillation (ENSO) is crucial to the interannual variability of tropical cyclone (TC) genesis over the western North Pacific (WNP). However, most state-of-the-art climate models exhibit a consistent pattern of uncertainty in the simulated TC genesis frequency (TCGF) over the WNP in ENSO phases. Here, we analyze large ensemble s...

In the latter half of the twentieth century, a significant climate phenomenon “diurnal asymmetric warming” emerged, wherein global land surface temperatures increased more rapidly during the night than during the day. However, recent episodes of global brightening and regional droughts and heatwaves have brought notable alterations to this asymmetr...

The influence of the El Niño-Southern Oscillation (ENSO) in the Asian monsoon region can persist through the post-ENSO summer, after the Sea Surface Temperature (SST) anomalies in the tropical Pacific have dissipated. The long persistence of coherent post-ENSO anomalies is caused by a positive feedback due to interbasin ocean-atmospheric coupling,...

The responses of the Earth’s climate system to positive and negative CO2 emissions are not identical in magnitude, resulting in hysteresis. In particular, the degree of global precipitation hysteresis varies markedly among Earth system models. Based on analysis of Earth’s energy budget, here we show that climate sensitivity controls the degree of g...

The northeastern Pacific climate system is featured by an extensive low-cloud deck off California on the southeastern flank of the subtropical high that accompanies intense northeasterly trades and relatively low sea surface temperatures (SSTs). This study assesses climatological impacts of the low-cloud deck and their seasonal differences by regio...

Tropical cyclones do not form easily near the equator but can intensify rapidly, leaving little time for preparation. We investigate the number of near-equatorial (originating between 5°N and 11°N) tropical cyclones over the north Indian Ocean during post-monsoon season (October to December) over the past 60 years. The study reveals a marked 43% de...

During recent decades, both greenhouse gases (GHGs) and anthropogenic aerosols (AAs) drove major changes in the Earth's energy imbalance. However, their respective fingerprints in changes to ocean heat content (OHC) have been difficult to isolate and detect when global or hemispheric averages are used. Based on a pattern recognition analysis, we sh...

The northeastern Pacific climate system is featured by an extensive low-cloud deck off California on the southeastern flank of the subtropical high that accompanies intense northeasterly trades and relatively low sea surface temperatures (SSTs). This study assesses climatological impacts of the low-cloud deck and their seasonal differences by regio...

In the summer of 2022, a long-lasting La Niña entered its third year. In Asia, southern China was in the grip of a historic drought while heavy rainfall ravaged Pakistan. Using a climate model forced by observed sea surface temperatures (SST) over the equatorial Pacific, we show that the back-to-back La Niña events from 2020 to 2022 is a key contri...

Since the early 2010s, anthropogenic aerosols have started decreasing in East Asia (EA) while have continued to increase in South Asia (SA). Yet the climate impacts of this Asian aerosol dipole (AAD) pattern remain largely unknown. Using a state-of-the-art climate model, we demonstrate that the climate response is distinctly different between the S...

Turbulence-enhanced mixing of upper ocean heat allows interaction between the tropical atmosphere and cold water masses that impact climate at higher latitudes thereby regulating air-sea coupling and poleward heat transport. Tropical cyclones (TCs) can drastically enhance upper ocean mixing and generate powerful near-inertial internal waves (NIWs)...

Most state-of-art models project a reduced equatorial Pacific east-west temperature gradient and a weakened Walker circulation under global warming. However, the causes of this robust projection remain elusive. Here, we devise a series of slab ocean model experiments to diagnostically decompose the global warming response into the contributions fro...

This study investigates the transient evolution of tropical Pacific sea surface temperature (SST) responses to a constant northern high latitude solar heating in fully coupled CESM 1.2. The study identifies two stages through multiple ensemble runs. (1) In the first three years, a hemispherically asymmetric pattern emerges, caused by air-sea intera...

Tropical rainfall variations are of direct societal relevance and drive climate variations worldwide via teleconnections. The convective rainfall tends to occur when sea surface temperature (SST) exceeds a threshold, SST thr , usually taken to be constant in time and space. We analyze 40-year monthly observations and find that SST thr varies by up...

The Indonesian Throughflow (ITF) is projected to slow down under anthropogenic warming. Several mechanisms—some mutually conflicting—have been proposed but the detailed processes causing this slowdown remain unclear. By turning on/off buoyancy and wind forcings globally and in key regions, this study investigates the dynamical adjustments underlyin...

The Southern Ocean has warmed substantially, and up to early 21st century, Antarctic stratospheric ozone depletion and increasing atmospheric CO2 have conspired to intensify Southern Ocean warming. Despite a projected ozone recovery, fluxes to the Southern Ocean of radiative heat and freshwater from enhanced precipitation and melting sea ice, ice s...

The northeastern Pacific climate system is featured by an extensive low-cloud deck off California on the southeastern flank of the subtropical high that accompanies intense northeasterly trades and relatively low sea surface temperatures (SSTs). This study investigates climatic impacts of the low-cloud deck by turning low-cloud radiative forcing on...

Positive feedbacks in climate processes can obscure the initial drivers of climate phenomena. Some recent global climate model (GCM) studies partially circumvent this issue by controlling the wind stress felt by the surface ocean such that the atmosphere and ocean become mechanically decoupled. Most mechanical decoupling studies have chosen to over...

Plain Language Summary By decomposing the atmospheric circulation to its irrotational and nondivergent components, we integrated the three‐dimensional structure of the Hadley circulation (HC), and investigate its interactions with El Niño‐Southern Oscillation (ENSO). In particular, we focus on the zonal variation of the HC and its equatorial‐symmet...

The role of sea surface temperature (SST) variability in the pre-monsoonal (April to July) intraseasonal oscillation (ISO) over the South China Sea (SCS) is investigated using the Community Earth System Model Version 2 (CESM2). An Atmospheric Model Intercomparison Project (AMIP) simulation forced by daily sea surface temperatures (SSTs) derived fro...

Tropical cyclones (TCs) mix vertical temperature gradients in the upper ocean and generate powerful near-inertial internal waves (NIWs) that propagate down into the deep ocean. Globally, downward mixing of heat during TC passage causes warming in the seasonal thermocline and pumps 0.15-0.6 PW of heat into the unventilated ocean. The final distribut...

Plain Language Summary Anthropogenic aerosols are an important radiative forcing on the climate system contributing to observed climate variability. In prior modeling studies, idealized aerosol‐like forcing applied to Northern Hemisphere high latitude regions has resulted in a tropical La Niña‐like response in the Eastern Equatorial Pacific. In thi...

Plain Language Summary In December 2015 at Paris, United Nations agreed to hold the increase in the global average temperature to “well below” 2°C above pre‐industrial levels and pursuing efforts to limit 1.5°C above pre‐industrial levels. It naturally leads to a question as to when these targets will reach. However, under a business‐as‐usual scena...

The Hadley circulation (HC) is often considered zonally uniform and defined using the zonally averaged mass stream function (MSF). However, the longitudinal distribution of the overturning circulation is far from uniform, which has profound impacts on regional climates. This study uses a recently developed technique to examine the three‐dimensional...

In the mid‐latitude North Pacific, the wintertime ocean heat loss reaches the maximum in the Kuroshio‐Oyashio Extension (KOE) region. However, the mixed layer depth (MLD) there is shallow (<50 m), flanked by a zonal band of deep MLD (>100 m) on either side. Such an observed mixed layer pattern is not reproduced by coarse‐resolution or mesoscale edd...

El Niño-Southern Oscillation (ENSO) is an important but not the only source of interannual variability over the Indo-western Pacific. Non-ENSO forced variability in the region has received recent attention because of the implications for rainy season prediction. Using a 35-member CESM1 Large Ensemble (CESM-LE) and 30 CMIP6 models, this study shows...

Theory1 and numerical modelling2 suggest that tropical cyclones (TCs) will strengthen with rising ocean temperatures. Even though models have reached broad agreement on projected TC intensification3–5, observed trends in TC intensity remain inconclusive and under active debate6–10 in all ocean basins except the North Atlantic, where aircraft reconn...

Cross-equatorial ocean heat transport (OHT) changes have been found to damp meridional shifts of the intertropical convergence zone (ITCZ) induced by hemispheric asymmetries in radiative forcing. Zonal-mean energy transport theories and idealized model simulations have suggested that these OHT changes occur primarily due to wind-driven changes in t...

Low clouds frequent the subtropical northeastern Pacific (NEP) and interact with the local sea surface temperature (SST) to form positive feedback. Wind fluctuations drive SST variability through wind-evaporation-SST (WES) feedback, and surface evaporation also acts to damp SST. This study investigates the relative contributions of these feedbacks...

Coherently coupled ocean-atmosphere variability of the tropical Indo-Pacific Oceans gives rise to the predictability of Asian summer climate. Recent advances in Indo-western Pacific Ocean capacitor (IPOC) theory and the relationship with El Niño-Southern Oscillation (ENSO) are reviewed. The IPOC features tropical Indian Ocean (TIO) warming and an a...

This study investigates the effect of ocean dynamics on the tropical climate response to localized radiative cooling over three northern extratropical land regions using hierarchical model simulations that vary in the degree of ocean coupling. Without ocean dynamics, the tropical climate response is independent of the extratropical forcing location...

Some climate variables do not show the same response to declining atmospheric CO 2 concentrations as before the preceding increase. A comprehensive understanding of this hysteresis effect and its regional patterns is, however, lacking. Here we use an Earth system model with an idealized CO 2 removal scenario to show that surface temperature and pre...

Excessive precipitation over the southeastern tropical Pacific is a major common bias that persists through generations of global climate models. While recent studies suggest an overly warm Southern Ocean as the cause, models disagree on the quantitative importance of this remote mechanism in light of ocean circulation feedback. Here, using a multi...

Arctic sea ice has decreased substantially and is projected to reach a seasonally ice-free state in the coming decades. Little is known about whether dwindling Arctic sea ice is capable of influencing the occurrence of strong El Niño, a prominent mode of climate variability with global impacts. Based on time slice coupled model experiments, here we...

The Indian Ocean has an intriguing intertropical convergence zone (ITCZ) south of the equator year-round, which remains largely unexplored. Here we investigate this Indian Ocean ITCZ and the mechanisms for its origin. With a weak semiannual cycle, this ITCZ peaks in January–February with the strongest rainfall and southernmost location and a northe...

The tropical Pacific exhibits decadal El Niño-Southern Oscillation (ENSO)-like variability, characterized by meridionally broad sea surface temperature anomalies in the eastern Pacific. In this study, we focus on the variability in the equatorial Pacific band (5°S–5°N), termed equatorial Pacific decadal variability (EPDV). While it is known that oc...

Tropical rainfall is important for regional climate around the globe. In a warming climate forced by rising CO2, the tropical rainfall will increase over the equatorial Pacific where sea surface warming is locally enhanced. Here, we analyze an idealized CO2 removal experiment from the Carbon Dioxide Removal Model Intercomparison Project and show th...

How the ocean circulation changes in a warming climate is an important but poorly understood problem. Using a global ocean model, we decompose the problem into distinct responses to changes in sea surface temperature, salinity, and wind. Our results show that the surface warming effect, a robust feature of anthropogenic climate change, dominates an...

Tropical climate response to greenhouse warming is to first order symmetric about the equator but climate models disagree on the degree of latitudinal asymmetry of the tropical change. Intermodel spread in equatorial asymmetry of tropical climate response is investigated by using 37 models from phase 6 of the Coupled Model Intercomparison Project (...

This study investigates the effect of ocean dynamics on the tropical climate response to localized radiative cooling over three northern extratropical land regions using hierarchical model simulations that vary in the degree of ocean coupling. Without ocean dynamics, the tropical climate response is independent of the extratropical forcing location...

This study investigates the formation mechanism of the ocean surface warming pattern in response to a doubling CO 2 with a focus on the role of ocean heat uptake (or ocean surface heat flux change, Δ Q net ). We demonstrate that the transient patterns of surface warming and rainfall change simulated by the dynamic ocean–atmosphere coupled model (DO...

The classical theory predicts that a geostrophically balanced mesoscale eddy can cause a sea surface temperature (SST) anomaly related to Ekman pumping. Previous studies show that an eddy-induced SST anomaly can result in a sea surface latent heat flux (LH) anomaly at a maximum magnitude of ∼O(10) Wm–2, decaying radially outward from the center to...

Anthropogenic aerosols (AAs) induce global and regional tropospheric circulation adjustments due to the radiative energy perturbations. The overall cooling effects of AA, which mask a portion of global warming, have been the subject of many studies but still have large uncertainty. The interhemispheric contrast in AA forcing has also been demonstra...

The Subantarctic Mode Water (SAMW) forms in the deep mixed layer north of the Antarctic Circumpolar Current and spreads northward into the subtropical gyre. The subtropical South Indian Countercurrent (SICC) flows eastward on the north flank of the thick SAMW layer within 22° – 32°S from south of Madagascar at around 25°S, 50°E toward western Austr...

The Southern Ocean (>30° S) has taken up a large amount of anthropogenic heat north of the Subantarctic Front (SAF) of the Antarctic Circumpolar Current (ACC). Poor sampling before the 1990s and decadal variability have heretofore masked the ocean’s dynamic response to this warming. Here we use the lengthening satellite altimetry and Argo float rec...

The reorganization of the Atlantic Meridional Overturning Circulation (AMOC) is often associated with changes in Earth's climate. These AMOC changes are communicated to the Indo-Pacific basins via wave processes and induce an overturning circulation anomaly that opposes the Atlantic changes on decadal to centennial time scales. We examine the role...