npj Climate and Atmospheric Science最新文献

In this work, we examine connections between patterns of future Greenland precipitation and large-scale atmospheric circulation changes over the Northern Hemisphere. In the last three decades of the 21st century, CMIP5 and CMIP6 ensemble mean precipitation significantly decreases over the northern part of the North Atlantic Ocean with respect to 1951–1980. This drying signal extends from the ocean to the southeastern margin of Greenland. The 500 hPa geopotential height change shows a clear pattern including a widespread increase across the Arctic with a negative anomaly centered over Iceland and surrounding regions. To identify the mechanisms linking atmospheric circulation variability with Greenland precipitation, we perform a singular value decomposition (SVD) and center of action (COA) analysis. We find that a northeastward shift of the Icelandic Low (IL) under the SSP5‐8.5 warming scenario leads to the drying signal found in southeast Greenland. This implies that the IL location will have a strong influence on precipitation changes over southeast Greenland in the future, impacting projections of Greenland ice sheet surface mass balance.

Climate change poses direct and indirect threats to public health, including exacerbating air pollution. However, the influence of rising temperature on air quality remains highly uncertain in the United States, particularly under rapid reduction in anthropogenic emissions. Here, we examined the sensitivity of surface-level fine particulate matter (PM_2.5) and ozone (O₃) to summer temperature anomalies in the contiguous US as well as their decadal changes using high-resolution datasets generated by machine learning. Our findings demonstrate that in the eastern US, stringent emission control strategies have significantly reduced the positive responses of PM_2.5 and O₃ to summer temperature, thereby lowering the population exposure associated with warming-induced air quality deterioration. In contrast, PM_2.5 in the western US became more sensitive to temperature, highlighting the urgent need to manage and mitigate the impact of worsening wildfires. Our results have important implications for air quality management and risk assessments of future climate change.

Tropical cyclone (TC) precipitation has led to escalating urban flooding and transportation disruptions in recent years. The volatility of the TC rain rate (RR) over short periods complicates accurate forecasting. Here, we use satellite-based observational rainfall datasets from 1998 to 2019 to calculate changes in TC 24-h RR and quantify the temporal stability of TC precipitation. We demonstrate a significant global increase in the annual temporal stability of TC RR across the total rainfall area, inner-core, and rainband areas. Specifically, the probabilities of rapid RR increase and decrease events in the TC total rainfall area decreased at rates of –1.74 ± 0.57% per decade and –2.23 ± 0.55% per decade, respectively. Based on the reanalysis dataset, we propose that the synergistic effects of increased atmospheric stability and total column water vapor—both resulting from anthropogenic warming at low latitudes—are potentially associated with this trend.

Impacts of aerosol particles on clouds, precipitation, and climate remain one of the significant uncertainties in climate change. Aerosol particles entrained at cloud top and edge can affect cloud microphysical and macrophysical properties, but the process is still poorly understood. Here we investigate the cloud microphysical responses to the entrainment of aerosol-laden air in the Pi convection-cloud chamber. Results show that cloud droplet number concentration increases and mean radius of droplets decreases, which leads to narrower droplet size distribution and smaller relative dispersion. These behaviors are generally consistent with the scenario expected from the first aerosol-cloud indirect effect for a constant liquid water content (L). However, L increases significantly in these experiments. Such enhancement of L can be understood as suppression of droplet sedimentation removal due to small droplets. Further, an increase in aerosol concentration from entrainment reduces the effective radius and ultimately increases cloud optical thickness and cloud albedo, making the clouds brighter. These findings are of relevance to the entrainment interface at stratocumulus cloud top, where modeling studies have suggested sedimentation plays a strong role in regulating L. Therefore, the results provide insights into the impacts of entrainment of aerosol-laden air on cloud, precipitation, and climate.

Extended-range forecast has long maintained a difficult point for the seamless forecast system due to the lack of predictability, with intraseasonal oscillation (ISO), an important signal in many high-impact weather events, being an important source of that. To improve the accuracy of ISO extended-range forecast and make up the gaps in previous researches in this regard, a data-driven model ISOX is proposed for the intraseasonal components of atmospheric fields. Compared with the subseasonal forecast results from climate forecast system (CFS), and the climatological forecast, ISOX achieves higher accuracy for lead times longer than 13 days, with few spatial or temporal weak points. It also performed better in predicting the positive 2 m temperature ISO and lower tropospheric conditions in a heatwave event, surpassing CFS for lead times longer than 13 days. Finally, through gradient evaluation, the model is proved to be able to study the ISO signal movements of atmospheric systems. Thus, the success of this model may shed light on improving extended-range forecast skills and assist the timely detection and prevention of possible meteorological disasters.

Severe convective storms and tornadoes rank among nature’s most hazardous phenomena, inflicting significant property damage and casualties. Near-surface weather conditions are closely governed by large-scale synoptic patterns. It is crucial to delve into the involved multiscale associations to understand tornado potential in response to climate change. Using clustering analysis, this study unveils that leading synoptic patterns driving tornadic storms and associated spatial trends are distinguishable across geographic regions in the U.S. Synoptic patterns with intense forcing featured by intense upper-level eddy kinetic energy and a dense distribution of Z500 fields dominate the increasing trend in tornado frequency in the southeast U.S., generating more tornadoes per event. Conversely, the decreasing trend noted in certain regions of the central Great Plains is associated with weak upper-level synoptic forcing. These findings offer an explanation of observational changes in tornado occurrences, suggesting that the physical mechanisms driving those changes differ across regions.

Extreme climate events have increasingly threatened global terrestrial ecosystems in recent decades. In spring 2023, Southwest China (SWC) experienced unprecedented heatwaves and droughts. Using multiple satellite-based datasets, we found that these events led to the most significant declines in gross primary productivity (GPP) and the enhanced vegetation index (EVI) for the past two decades, with lagged effects persisting until August in the drought-affected area. Unlike the widespread and persistent drought of 2010, the record-breaking heatwaves in April and May 2023 sustained and intensified the drought stress. Elevated temperatures and suppressed precipitation, driven by anomalous atmospheric circulations, exacerbated the soil moisture (SM) shortages and increased the atmospheric vapor pressure deficit (VPD), restricting water availability and carbon uptake for vegetation photosynthesis. Our findings reveal that, during the 2023 extreme event in SWC, the decreases in forest productivity were primarily driven by low SM anomalies, while the decreases in the grassland and cropland productivity mainly resulted from abnormally high VPDs. This study highlights the combined effects of low SM and high VPD anomalies caused by a compound heatwave–drought event on vegetation growth in SWC and provides valuable insights for future assessments of regional extreme climate events on vegetation growth.

Observations reveal Antarctic sea ice expansion and Southern Ocean surface cooling trends from 1979 to 2014, whereas climate models mostly simulate the opposite. Here I use historical ensemble simulations with multiple climate models to show that sea-ice natural variability enables the models to simulate an Antarctic sea ice expansion during this period under anthropogenic forcings. Along with sea-ice expansion, Southern Ocean surface and subsurface temperatures up to 50^oS, as well as lower tropospheric temperatures between 60^oS and 80^oS, exhibit significant cooling trends, all of which are consistent with observations. Compared to the sea-ice decline scenario, Antarctic sea ice expansion brings tropical precipitation changes closer to observations. Neither the Southern Annular Mode nor the Interdecadal Pacific Oscillation can fully explain the simulated Antarctic sea ice expansion over 1979–2014, while the sea-ice expansion is closely linked to surface meridional winds associated with a zonal wave 3 pattern.

The South Asian summer monsoon (SAM) bears significant importance for agriculture, water resources, economy, and environmental aspects of the region for nearly 2 billion people. To minimize the adverse impacts of global warming, Stratospheric Aerosol Intervention (SAI) has been proposed to lower surface temperatures by reflecting a portion of solar radiation back into space. However, the effects of SAI on SAM are still very uncertain. Our study identifies the main drivers leading to a reduction in the mean and extreme summer monsoon precipitation under SAI. These include SAI-induced lower stratospheric warming and the associated weakening of the northern hemispheric subtropical jet, changes in the upper-tropospheric wave activities, geopotential height anomalies, a reduction in the strength of the Asian Summer Monsoon Anticyclone, and, to some degree, local dust changes. As the interest in SAI research grows, our results demonstrate the urgent need to further understand SAM variability under different SAI scenarios.

Land use changes (LUC) and global warming (GW) significantly impact the Maritime Continent’s (MC) hydro-climate, but their effects on extreme precipitation events are underexplored. This study investigates the impacts of LUC and GW on wet and dry extremes in the MC using Community Earth System Model (CESM)simulations, analyzing 55 years for LUC and 200 years for GW. We find that LUC-induced deforestation increases surface warming, enhancing atmospheric instability and favoring local convection, leading to more frequent heavy precipitation. Meanwhile, GW amplifies the atmosphere’s water-holding capacity, further intensifying wet extremes. Our findings reveal a “wet-get-wetter, dry-get-drier” pattern driven by different mechanisms: dynamic processes primarily influence wet extremes under LUC, while changes in evapotranspiration control dry extremes. In contrast, under GW, wet extremes are driven by dynamic processes, while dry extremes are influenced by reduced moisture availability and weakened atmospheric circulation. This highlights the need for land management to address rising extreme risks.