npj Climate and Atmospheric Science最新文献

We unravel the response of terrestrial ecosystems in India to Tropical Cyclones (TCs) originating in the North Indian Ocean (NIO). We find that about 34.6% of TCs drove greening and 65.4% caused browning response of vegetation during 2000–2020. TC-induced greening is more likely for TCs originated in pre-monsoon (100%) or monsoon (62.5%) than post-monsoon with large browning response (94%). Rainfall by TCs increases soil moisture (SM) and reduces climatic water deficit (CWD) for a moisture-stressed region, and its effective utilisation by vegetation triggers the greening response. Granger Causality reveals that TC-induced rain and greening response exhibit a maximum temporal lag of 40 days. The favourable vegetation response to TCs is a new insight as it sheds light on the complex Atmosphere-Land-Ocean (ALO) interactions on a regional scale. The findings can aid to improve climate models for better policy decisions aimed at climate adaptation and sustainability on both regional and global scales.

The effect of future climate change on the boreal winter response to strong El Niño is investigated using pacemaker simulations with the EC-Earth3-CC model constrained towards observed tropical Pacific sea surface temperature anomalies. Under the Shared Socioeconomic Pathway 2-4.5, the surface temperature response to strong El Niño intensifies in North America, northern Africa, Australia and the North Atlantic compared to present day. However, future strong El Niño has a weaker climate impact in southern America and Africa. Temperature extremes under strong El Niño intensify in the future in some regions, with more cool days in eastern North America, while warm days in northern South America decrease. Assuming that the characteristics of strong El Niño events will not change in the future, we distinguish between changes in El Niño teleconnections and background climate changes, and found that the latter dominates the absolute climate response to strong El Niño events.

The impact that biogenic emissions have on aerosol-cloud interactions across the Southern Ocean is poorly quantified. Here we use satellite and ship observations during austral summer to study these interactions. We present observational evidence that biogenic aerosols increase cloud condensation nuclei and cloud droplet number concentrations over the Southern Ocean off East Antarctica, coinciding with very low concentrations of ice-nucleating particles and higher occurrences of supercooled liquid-containing low-level clouds.

El Niño–Southern Oscillation (ENSO) was identified as the dominant factor influencing the East Asian summer monsoon (EASM), especially after the mid-1970s when the tropical Indian Ocean (TIO) response remarkably strengthened. Here, we find that the influence of ENSO on the EASM has been diminishing since the early 2000s. The EASM in wind anomalies associated with the positive phase of ENSO quickly disintegrates in August, changing from an anticyclone over the western North Pacific (WNPAC) to a cyclone over the western North Pacific (WNP), which exerts significant influence on the East Asia rainfall. These weakened EASM responses are closely linked to the changes in ENSO’s rate of decay around the early 2000s. During 1977–1999, ENSO events peaking in the boreal winter frequently display a gradual decay, triggering robust positive ocean–atmosphere feedback, which extends beyond the TIO and involves the WNP. The resultant North Indian Ocean (NIO) warming develops and persists through the decaying summer, maintaining the WNPAC in August. In contrast, ENSO events exhibit a faster decay during 2000–2022, leading to a weakened ENSO-induced TIO feedback. Additionally, the WNP warms up, accompanied by the collapse of the easterly wind response, contributing to the weak summer peak in the NIO. In turn, the weak NIO warming rapidly decays, which cannot sustain the WNPAC in August. This study emphasizes the crucial role of WNP air–sea coupling in the changing influences of ENSO on the EASM.

The northeast (NE) Pacific has experienced significant marine heatwaves (MHWs) in recent years, commonly known as “warm blobs.” This study examines the impact of Arctic warming, particularly in the Eastern Siberian-Chukchi Sea (ES-CS) region, on the occurrence of these warm blobs during boreal winters. We found that Arctic warming triggers a positive phase of the Tropical/Northern Hemisphere-like (TNH-like) atmospheric circulation, creating a pronounced high-pressure system over the Alaskan region. This system leads to easterly wind anomalies that weaken prevailing westerlies, reducing heat loss from the ocean to the atmosphere and cold advection in the upper ocean. Consequently, sea surface temperatures rise, favoring the development of warm blobs. A numerical experiment confirmed that the projected changes in the ES-CS region impact warm blobs occurrences by inducing this high-pressure system, linking Arctic warming to MHWs in the NE Pacific.

This study quantifies the influence of the pattern of sea surface temperature change in the tropical Pacific on tropical cyclone hazard. After downscaling a climate model with an “El Niño-like” forced response, it is found that the “El Niño-like” pattern of warming induces an “El Niño-like” change to tropical cyclone hazard. The magnitude of hazard change owing to the “El Niño-like” pattern of warming is estimated to be around the same order of magnitude as that driven by the forced response that does not project onto the same pattern of warming, highlighting the sensitivity of local tropical cyclone hazard to the pattern of warming. Given the uncertainty around the future pattern of Pacific warming, a storyline with a “La Niña-like” pattern of warming, of similar magnitude to the observations, is created. In this scenario, near-term tropical cyclone hazard over coastal Asia and the Atlantic basin significantly increases.

The stratospheric CO budget is determined by CH₄ oxidation, OH-driven loss and atmospheric transport. These processes can be constrained using CO mole fractions and isotopic compositions, with the latter being largely unexplored. We present novel stratospheric observations of δ¹³C-CO and δ¹⁸O-CO vertical profiles, revealing distinct altitude-dependent trends. δ¹³C-CO decreases with altitude due to inverse ¹³C kinetic fractionation in the OH sink and ¹³C-depleted CO from CH₄ oxidation. In contrast, δ¹⁸O-CO increases with altitude, driven by ¹⁸O-rich oxygen from O(¹D) via O₃ photolysis and CO₂ photolysis. Our findings suggest that CO isotopes can act as valuable proxies for quantifying CO production from CO₂ photolysis. Incorporating CO mole fractions and isotopic data into global models enhances evaluations of the stratospheric CH₄ sink and OH abundance, improving our understanding of stratospheric water vapour and its radiative impacts.

Accurate and timely CO₂ emission inventories are essential for tracking climate change mitigation progress. This study conducts near real-time CO₂ emission estimates for China using different timely-updated activity data sources such as annual bulletins and monthly statistics. Comparing the results with emissions estimated by regular statistics, we find that emission estimates relying solely on either monthly statistics or annual bulletins have uncertainties. Prioritizing annual bulletins where available and supplementing with monthly statistics for the most recent year can balance accuracy and timeliness, yielding a median error of 1.3% across different update intervals. However, near real-time estimates of relative changes in annual CO₂ emissions bear large uncertainties regardless of the approach. For the six years investigated, near real-time estimates usually failed to capture the trends in annual emissions, indicating that those near real-time approaches are unreliable for estimating changes in CO₂ emissions due to notable differences between timely-updated and regular statistics.

Clarifying relationships between stable oxygen isotope ratios in precipitation (δ¹⁸O_p) and atmospheric circulations including the Indian Ocean Dipole (IOD) and western Pacific subtropical high (WPSH) forms the basis of paleocirculation reconstructions. However, whether the IOD and WPSH modulate interannual variations of δ¹⁸O_p remains unclear. Here, we reveal the links between the IOD/WPSH and the annual δ¹⁸O_p in southern East Asia. We found that the IOD strongly influenced annual δ¹⁸O_p before 1999 by changes in moisture supply from different transport pathways and convection. However, the link became decoupled after 1999, resulting from the transition of the IOD from a symmetric to an asymmetric pattern. In contrast, significantly enhanced WPSH emerges as an important influence on annual δ¹⁸O_p after 1999. Therefore, the IOD and WPSH alternately influence interannual variation of δ¹⁸O_p around 1999. Our findings imply that signals of IOD and WPSH should be considered in different periods to better interpret paleoclimate records.

Ship traffic is known as an important contributor to air pollution. Regulations aimed at reducing sulfur oxide pollution by limiting the fuel sulfur content (FSC) may also decrease primary particulate matter (PM) emitted from ships. However, there is a knowledge gap regarding how the FSC affects secondary aerosol formation. The emissions from a research ship engine operated with either low sulfur heavy fuel oil (LS-HFO) (FSC = 0.5%) or marine gas oil (MGO) (FSC = 0.01%), were photochemically processed in the oxidation flow reactor “PEAR” to achieve an equivalent photochemical age between 0 and 9 days in the atmosphere. FSC was found to have no significant impact on secondary organic aerosol formation after 3 days of aging, at 1.7 ± 0.4 g/kg for MGO and 1.5 ± 0.4 g/kg for LS-HFO. Furthermore, the composition and oxidative pathways remained similar regardless of FSC. However, because of the higher secondary SO₄ formation and primary aerosol emissions, LS-HFO had significantly higher total PM than MGO.