Pengfei Zhang

• PhD
• Assistant Research Professor at Pennsylvania State University

Previous studies have extensively investigated the impact of Arctic sea ice anomalies on the midlatitude circulation and associated surface climate in winter. However, there is an ongoing scientific debate regarding whether and how sea ice retreat results in the observed cold anomaly over the adjacent continents. We present a robust “cold Siberia”...

In recent decades, Arctic sea-ice coverage underwent a drastic decline in winter, when sea ice is expected to recover following the melting season. It is unclear to what extent atmospheric processes such as atmospheric rivers (ARs), intense corridors of moisture transport, contribute to this reduced recovery of sea ice. Here, using observations and...

Despite global warming, the sea surface temperature (SST) in the subpolar North Atlantic has decreased since the 1900s. This local cooling, known as the North Atlantic cold blob, signifies a unique role of the subpolar North Atlantic in uptaking heat and hence impacts downstream weather and climate. However, a lack of observational records and thei...

The weak stratospheric polar vortex (SPV) is usually linked to Northern Hemisphere cold spells. Based on the fifth generation of ECMWF atmospheric reanalysis and WACCM model experiments, we use K-means cluster analysis to extract the zonally asymmetric pattern of October-February stratospheric variability, which involves a stretched SPV and hence l...

Cold winters over Eurasia often coincide with warm winters in the Arctic, which has become known as the “Warm Arctic-Cold Eurasia” pattern. The extent to which this observed correlation is indicative of a causal response to sea-ice loss is debated. Here, using large multi-model ensembles of coordinated experiments, we find that the Eurasian tempera...

Sea surface temperature (SST) in the subpolar North Atlantic has significantly decreased at a rate of − 0.39 (±0.23\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm 0...

Extreme cold events over North America such as the February 2021 cold wave have been suggested to be linked to stratospheric polar vortex stretching. However, it is not resolved how robustly and on which timescales the stratosphere contributes to the surface anomalies. Here we introduce a simple measure of stratospheric wave activity for reanalyses...

Over the past four decades, Arctic sea ice has experienced a drastic decline in winter when it is recovering from summer melt. Observations and model simulations reveal that atmospheric rivers are more frequently reaching the Arctic in winter, preventing the sea ice from growing to the extent that is possible at the freezing temperature.

Sea surface temperature (SST) in the subpolar North Atlantic has significantly decreased at a rate of -0.39 (\(\pm 0.23\)) K/century during 1900–2020, which runs counter to global warming due to anthropogenic forcing. The cooling in the subpolar North Atlantic, known as the North Atlantic cold blob, could be driven by a host of mechanisms involving...

Despite the severe impacts on Eurasian extreme weather, the mechanisms and causes of the “warm Arctic–cold Eurasia” (WACE) pattern and its opposite phase “cold Arctic–warm Eurasia” (CAWE) remain a subject of active debate. With a focus on subseasonal time scale, this study investigates the roles of atmospheric variability and Arctic sea ice in the...

Please see the published version at: https://www.nature.com/articles/s41558-023-01599-3

The Asian monsoon anticyclone (AMA) exhibits a trimodal distribution of sub‐vortices and the western Pacific is one of the preferred locations. Amplification of the western Pacific anticyclone (WPA) is often linked with eastward eddy shedding from the AMA, although the processes are not well understood. This study investigates the dynamics driving...

Plain Language Summary A weak polar vortex in the winter stratosphere is likely associated with cold spells at the surface, yet there are large uncertainties in predicting surface cold events based on stratospheric signals. This study introduces a new method to separate stratospheric variability into the leading modes of zonally symmetric and asymm...

Atmospheric rivers (ARs), narrow intense moisture transport, account for much of the poleward moisture transport in midlatitudes. While studies have characterized AR features and the associated hydrological impacts in a warming climate in observations and comprehensive climate models, the fundamental dynamics for changes in AR statistics (e.g., fre...

While there is substantial evidence for tropospheric jet shift and Hadley cell expansion in response to greenhouse gas increases, quantitative assessments of individual mechanisms and feedback for atmospheric circulation changes remain lacking. We present a new forcing-feedback analysis on circulation response to increasing CO 2 concentration in an...

While the relationship between the Arctic sea ice loss and midlatitude winter climate has been well discussed, especially on the seasonal mean scale, it remains unclear whether the Arctic sea ice condition affects the predictability of North American cold weather on the subseasonal time scale. Here we find that, in the presence of low Barents-Kara...

Understanding what physically sets the shape of temperature distributions will enable more robust predictions of local temperature with global warming. We derive the relationship between the temperature distribution shape and the advection of temperature conditionally averaged at each temperature percentile. This enables quantification of the shift...

The latitude of the westerly jet stream is influenced by a variety of climate forcings, but their effects on the jet latitude often manifest as a tug of war between tropical forcing (e.g., tropical upper‐tropospheric warming) and polar forcing (e.g., Antarctic stratospheric cooling or Arctic amplification). Here we present a unified forcing‐feedbac...

A winter Eurasian cooling trend and a large decline of winter sea ice concentration (SIC) in the Barents-Kara Seas (BKS) are striking features of recent climate changes. The question arises as to what extent these phenomena are related. A mechanism is presented that establishes a link between recent winter SIC decline and midlatitude cold extremes....

This study uses a set of idealized aquaplanet model experiments to investigate the linkage between the Asian summer monsoon circulation and tropopause fold activity. It is found that folds tend to occur on the northwestern side of the upper-level anticyclone associated with the monsoon circulation and are generated due to intensified monsoon circul...

To better understand the dynamical mechanism that accounts for the observed lead-lag correlation between the early winter Barents–Kara Sea (BKS) sea ice variability and the later winter midlatitude circulation response, a series of experiments are conducted using a simplified atmospheric general circulation model with a prescribed idealized near-su...

Occupying the upper troposphere over subtropical Eurasia during boreal summer, the South Asian high (SAH) is thought to be a regulator of the East Asian summer monsoon (EASM), which is particularly important for regional climate over Asia. However, there is feedback of the condensational heating associated with EASM precipitation to SAH variability...

Tibetan Plateau (TP) vortices and the related 10-30-day intraseasonal oscillation in May-September 1998 are analyzed using the twice-daily 500-hPa synoptic weather maps, multiple reanalysis datasets, and satellite-retrieved brightness temperature. During the analysis period, distinctively active and suppressed periods of TP vortices genesis are not...

The Southern Hemisphere subtropical anticyclones (SAs) are important features of the Earth's climate. A broad consensus among Coupled Model Intercomparison Project phase 3 and phase 5 climate models suggests an intensification of summer SAs over SH oceans in association with the increase in greenhouse gas concentrations in the atmosphere. Diagnosti...

Aims The Amazon basin plays an important role in the global carbon budget. Interannual climate variability associated with El Niño can affect the Amazon ecosystem carbon balance. In recent years, studies have suggested that there are two different types of El Ninos: eastern-Pacific (EP) El Niño and central-Pacific (CP) El Niño. The impacts of two t...