JGR–Atmospheres

This study investigates the response of surface air temperature (SAT) to strong tropical volcanic eruptions (STVEs), focusing on the seasonal anchoring of SAT recovery, using the Coupled Model Intercomparison Project 5 (CMIP5) and CMIP6 climate model outputs. The decrease in SAT was more significant in the Northern Hemisphere than in the Southern Hemisphere. After the STVEs, shortwave radiation at the surface (SW) decreased rapidly and reached a minimum in approximately 6 months, whereas the decrease in SAT lasted for approximately 1 year; thus, the SAT minima lagged behind those of SW. The recovery of SAT from the major minimum SAT after the STVEs occurred in the same seasons, the second boreal autumn and winter. The SAT recovery occurred during the climatologically low solar radiation season after the STVEs. During this season, the decreasing effects of the downward SW (DSRS) by volcanic aerosols could become negligible. The weakening of the decrease in SAT and DSRS had a seasonal cycle in the high-latitude regions of both hemispheres, which could be a significant factor in the seasonal alignment of returning SATs. Furthermore, the SAT response to the El Niño–Southern Oscillation (ENSO) was examined using composite analysis based on the initial state of ENSO. The influence of ENSO on surface cooling after the STVE was at least 1/5 that of the STVEs and might exceed that of the STVEs, particularly in moderate STVEs. These results were commonly found in the CMIP5 and CMIP6 climate models.

The Multivariate compound heatwaves (MCHWs) present a significant risk to human health and ecological diversity, which attract widespread attention from researchers and society. The intensity and variability of summer MCHWs over Western Europe (WE) (MCHWs_WE) have substantially increased over the last two decades. The growing chance of such events is likely related to human activity-induced climate change. However, the possible contributions from multiple atmospheric boundary forcing remain unclear. This study investigates the combined effects of North Atlantic sea surface temperature (SST), Tibetan Plateau (TP) snow cover (SC), and Arctic sea ice (SIC) on the variability of extreme summer MCHWs_WE. Observational analysis shows that an intensified anticyclonic system prevailing over WE, one of the centers of an atmospheric wave train dominating the North Atlantic-Europe sector and persists from late spring to summer, is the essential system contributing to the extreme MCHWs_WE. Spring North Atlantic SST anomalies in the form of a dipole pattern persist from spring to summer and contribute to the summer extreme MCHWs_WE by exciting a downward propagating Rossby wave train pattern. Additionally, excessive late spring SC over the western TP and SIC over the Arctic, which are stimulated by the North Atlantic anomalous SST-related wave train, can intensify the MCHWs_WE-related anticyclonic system through vertical circulation and wave energy transport. The study further quantifies the relative contributions of the aforementioned factors. The findings of this study could potentially offer valuable insights for improving the prediction skill of summer extreme MCHWs_WE.

Anemophilous (wind-driven) pollen is one type of primary biological aerosol particle, which can rupture under high humidity conditions and form smaller sub-pollen particles (SPPs). Both pollen and SPPs can reach the upper troposphere under convective conditions, acting as cloud condensation nuclei (CCN) and ice nucleating particles (INPs), thus influencing cloud formation and precipitation. However, the impacts of these biological aerosols on cold cloud formation and local climate remain unclear as there are large uncertainties on their emission flux and ice nucleating abilities. Here, we incorporate pollen emission and rupture processes in the Weather Research and Forecasting Model with Chemistry (WRF-Chem) simulations and update the Morrison microphysics scheme within WRF-Chem using aerosol-aware INP parameterizations to account for pollen in addition to other anthropogenic and biogenic aerosol. INP parameterizations for pollen and SPP are derived from laboratory experiments. When including pollen rupture rates as observed in a series of chamber studies, SPP concentrations increase, leading to an increase of cloud ice and water by up to 50% and potentially extending the duration of the convective system. Among all simulated hydrometeors, graupel and raindrops exhibit the largest enhancements from the inclusion of SPPs, with intensifying precipitation at the backside of the convective system and a greater spatial extent. Sensitivity simulations indicate that SPPs have a greater effect on cloud microphysical processes than whole pollen grains, and further observational evidence is needed to constrain these processes.

Wind and solar energy are crucial for meeting the growing energy demand and mitigating the impact of climate change, and their sources show a climate-dependence. Here, based on the outputs from two regional climate models (RCMs) driven by three global climate models within the Coordinated Regional Climate Downscaling Experiments-East Asia (CORDEX-EA-II), the effects of future climate change on wind power density (WPD) and photovoltaic power potential (PVP) in China under the Representative Concentration Pathway (RCP) 2.6 scenario and RCP8.5 scenario are comprehensively investigated, and the sources of uncertainty are also quantified. Results show that all RCMs can reproduce the observed WPD and PVP in China by employing the Quantile Delta Mapping method for wind speed simulations. For the future projections, the annual averages of WPD and PVP in China tend to decrease by −11.67% to −1.7% and −4.6% to −1.12%, respectively, with more significant reduction under the RCP8.5 than under the RCP2.6. Note that uncertainties exist among the RCMs' simulations in terms of future projections and long-term trends. Further analysis reveals that the uncertainty in both WPD and PVP projections are primarily driven by the internal variability in most sub-regions except the Tibetan Plateau, where GCM uncertainty and emission scenarios play the dominant role in the uncertainty of WPD and PVP projection, respectively. This study highlights the potential benefits of controlling greenhouse gas emissions in enhancing and stabilizing renewable energy in China.

Precipitation plays an important role in cloud and aerosol processes over the Southern Ocean (SO). The main objective of this study is to characterize SO precipitation properties associated with SO stratocumulus clouds. We use data from the Southern Ocean Clouds Radiation Aerosol Transport Experimental Study (SOCRATES), and leverage observations from airborne radar, lidar, and in situ probes. We find that for the cold-topped clouds (cloud-top-temperature <0°C), the phase of precipitation with reflectivity >0 dBZ is predominantly ice, while reflectivity < −10 dBZ is predominantly liquid. Liquid-phase precipitation properties are retrieved where radar and lidar are zenith-pointing. Power-law relationships between reflectivity (Z) and rain rate (R) are developed, and the derived Z–R relationships show vertical dependence and sensitivity to the presence of droplets with diameters between 10 and 40 μm. Using derived Z–R relationships, a reflectivity-velocity (ZV) retrieval method, and a radar-lidar retrieval method, we derive rain rate and other precipitation properties. The retrieved rain rate from all three methods shows good agreement with in-situ aircraft estimates, with rain rates typically being quite light (<0.1 mm hr−1). We examine the vertical distribution of precipitation properties, and find that rain rate, precipitation number concentration, and precipitation liquid water all decrease as one gets closer to the surface, while precipitation size and distribution width increases. We also examine how cloud base rain rate (R CB ) depends on cloud depth (H) and aerosol concentration (N a ) for particles with a diameter greater than 70 nm, and find that R CB is proportional to H3.1Na−0.8 ${H}^{3.1}\,{N}_{a}^{-0.8}$.

Cloud impact on terrestrial evapotranspiration (ET) can be significant, while a fundamental understanding of ET response to cloud change has not been addressed in regional aspects. In this study, seven ET datasets from satellite and land surface models are used to analyze the summer ET in response to low cloud cover (LCC) over East Asia, in combination with satellite microwave and optical vegetation data, as well as ERA5 climatic and surface parameters. In general, all ET datasets present a strong negative relationship with LCC over dense vegetation (e.g., forests), which leads to the ET reduction of more than −0.5 mmday−1 under the large LCC increase, compared with the least cloudy sky conditions. Such reduction is stronger under more humid and denser forests (aridity index AI > 0.5 and enhanced vegetation index EVI > 0.6). In contrast, a positive relationship between ET and LCC presents over arid and sparse lands (AI < 0.2 and EVI < 0.2), accompanied by enhanced ET (>0.2 mmday−1). Analysis shows that under increased LCC conditions, substantial reduction in radiation availability results in the decline in both plant transpiration (ETveg) and soil evaporation (ETsoil) over humid dense vegetation, dominating the overall negative response. The increase of near-surface relative humidity over arid sparse vegetation may indicate a stronger moisture availability, which promotes ETsoil and partly offsets the negative effect of radiation reduction. The change of vegetation water content, indicated by a satellite microwave vegetation index, is important for ETveg over arid mountainous lands with cloud cover. These findings contribute new insights to the understanding of vegetation-atmosphere interactions.

No abstract is available for this article.

Large satellite discrepancies and model biases in representing precipitation over the Southern Ocean (SO) are related directly to the region's limited surface observations of precipitation. To help address this knowledge gap, the study investigated the precipitation characteristics and rain rate retrievals over the remote SO using ship-borne data of the Ocean Rainfall And Ice-phase precipitation measurement Network disdrometer (OceanRAIN) and dual-polarimetric C-band radar (OceanPOL) aboard the Research Vessel (RV) Investigator in the Austral warm seasons of 2016–2018. Seven distinct synoptic types over the SO were analyzed based on their radar polarimetric signatures, surface precipitation phase, and rain microphysical properties. OceanRAIN observations revealed that the SO precipitation was dominated by drizzle and light rain, with small-sized raindrops (diameter <1 mm) constituting up to 47% of total accumulation. Precipitation occurred most frequently over the warm sector of extratropical cyclones, while concentrations of large-sized raindrops (diameter >3 mm) were prominent over synoptic types with colder and more convectively unstable environments. OceanPOL observations complement and extend the surface precipitation properties sampled by OceanRAIN, providing unique information to help characterize the variety of potential precipitation types and associated mechanisms under different synoptic conditions. Raindrop size distributions (DSD) measured with OceanRAIN over the SO were better characterized by analytical DSD forms with two-shape parameters than single-shape parameters currently implemented in satellite retrieval algorithms. This study also revised a rainfall retrieval algorithm for C-band radars to reflect the large amount of small drops and provide improved radar rainfall estimates over the SO.

We present estimates of gravity wave momentum fluxes calculated from Project Loon superpressure balloon data collected between 2013 and 2021. In total, we analyzed more than 5,000 days of data from balloon flights in the lower stratosphere, flights often over regions or during times of the year without any previous in-situ observations of gravity waves. Maps of mean momentum fluxes show significant regional variability; we analyze that variability using the statistics of the momentum flux probability distributions for six regions: the Southern Ocean, the Indian Ocean, and the tropical and extratropical Pacific and Atlantic Oceans. The probability distributions are all approximately log-normal, and using their geometric means and geometric standard deviations we statistically explain the sign and magnitude of regional mean and 99th percentile zonal momentum fluxes and regional momentum flux intermittencies. We study the dependence of the zonal momentum flux on the background zonal wind and argue that the increase of the momentum flux with the wind speed over the Southern Ocean is likely due to a varying combination of both wave sources and filtering. Finally, we show that as the magnitude of the momentum flux increases, the fractional contributions by high-frequency waves increases, waves which need to be parameterized in large-scale models of the atmosphere. In particular, the near-universality of the log-normal momentum flux probability distribution, and the relation of its statistical moments to the mean momentum flux and intermittency, offer useful checks when evaluating parameterized or resolved gravity waves in models.

A Moon-based sensor can observe the Earth as a single point and achieve disk-integrated measurements of outgoing longwave radiation (OLR), which significantly differs from low orbital, geostationary, and Sun–Earth L1 point platforms. In this study, a scheme of determining the disk-integrated Earth’s OLR based on a Moon-based platform is proposed. The observational solid angle was theoretically derived based on the Earth’s ellipsoid model and the disk-integrated observational anisotropic factor was estimated to eliminate the effects of the Earth’s radiant anisotropy. The simulated disk-integrated Earth's OLR obtained from a Moon-based platform varies periodically, due to changes in the observation geometry and Earth's scene distribution within the observed Earth’s disk. Clouds, meteorological parameters, and the land cover distribution notably affect the disk-integrated Earth’s OLR. By analyzing the disk-integrated Earth’s OLR from a Moon-based platform, significant variabilities were investigated. Additionally, the Earth’s shape and radiant anisotropy that affecting the disk-integrated Earth’s OLR were estimated. In conclusion, a more realistic Earth’s shape, the latest version of the angular distribution model (ADM), and accurate land cover and meteorological datasets are needed when determining the disk-integrated Earth’s OLR. It is expected the unique variability captured by this platform and its ability to complement traditional satellite data make it a valuable tool for studying Earth’s radiation budget and energy cycle, and contributing to diagnostic of the climate General Circulation Models (GCM) performance.

The influence of continental emissions on the origin and formation mechanisms of atmospheric particulate nitrate (ρ-NO3 −) aerosols in the marine boundary layer remains unclear. Here, synchronous observations of nitrogen isotope ratios (δ 15N–NO3 −) and oxygen isotope anomaly (Δ17O–NO3 −) in ρ-NO3 − were conducted across the Yellow Sea and Bohai Sea in Eastern China. Nitrate concentrations, δ 15N–NO3 − and Δ17O–NO3 − exhibited a pronounced north-to-south latitudinal gradient. Combined with backward air mass trajectory analysis, the high nitrate concentration and isotopic characteristics in the northern sea area were found to be affected by the continental outflow near China while the low values in the southern sea area were more related to the oceanic inflow. Stable isotope analysis in R (SIAR) indicated that near the northern sea area, the nitrate radicals (NO3) reacted with hydrocarbons (HC) or dimethyl sulfides (DMS) pathway (NO3 + HC/DMS) played a leading role in nitrate production, whereas the NO2 + OH pathway dominated near the southern sea area. Nitrate in the northern seas originated mainly from nitrogen oxides (NOx = NO + NO2, the gaseous precursor of nitrate) emitted from continental sources, especially coal combustion and biomass burning. While closer to the southern seas, the proportion of NOx generated in the marine environment (from ship and biogenic emissions) increased. Overall, the differential relative contributions of continental and marine atmospheric chemistry and NOx sources lead to the spatial distribution characteristics of atmospheric nitrate concentrations and isotopic values over the Yellow and Bohai Seas.

A large reservoir of saturation deficit air is known to exist over the northern Arabian Sea and the adjoining land regions during the peak of Indian summer monsoon (ISM). The strengthening of monsoon low-level jet (LLJ) in the northern parts of the Arabian Sea during the break phase of ISM helps in transporting this dry air toward northwestern India. Here, we show that, a weakening (strengthening) of the zonal flow over the northern Arabian Sea can reduce (enhance) the influx of the unsaturated air to the Northwest India and thereby enhance (reduce) precipitation there. The variability in the zonal flow over the northern Arabian Sea is a direct geostrophic response to the variability in the meridional pressure gradient over the Northwest India. The interannual variability in the mean sea level pressure over the region explains the inter-annual variability of ISM precipitation during July–August over northwestern India. The contribution of El Niño Southern Oscillation in the interannual variability of precipitation over this region is not significant.

The atmospheric river (AR) is a long, narrow, and transient corridor of strong horizontal water vapor transport. Various AR detection methods have been proposed, which have introduced significant uncertainty to the identified AR characteristics. This study has designed a data fusion algorithm to merge 12 data sets of different global and regional AR identification algorithms published by the Atmospheric River Tracking Method Intercomparison Project (ARTMIP) covering the period from 1980 to 2016. It aims to conduct frequency statistics to further research the global distribution, interannual variation, the trends in poleward shifting, and the impacted factors of AR occurrence. The quantitative results indicate an overall increasing trend in interannual variation, with a more pronounced growth trend observed in the oceanic region between 40 and 60ºS. Additionally, the study identifies a poleward shift in the peak latitude of AR occurrence frequency, with speeds of 0.589° and 0.769° per decade in the Northern and Southern Hemispheres, respectively. This shift may be associated with the tropical poleward expansion. Upon examining the relationship between AR frequency and sea surface temperature (SST) as well as zonal wind, the study finds that distinct dominant factors influence AR in different regions. AR events near the 30°N/S ocean are influenced more significantly by zonal wind than by SST. These findings shed light on the global characteristics of AR occurrences and provide insights into the factors governing their variability across different areas.

This study focuses on the interannual variability of winter mean surface air temperature (SAT) and subseasonal SAT reversal in North China, which have profound impacts on national life and economic activities. The analysis explores the temporal and spatial distribution characteristics of these variations and their relationship with the Eurasian Zonal Circulation (EZ). The findings reveal distinct interdecadal changes in North China’s winter mean SAT, along with a general subseasonal reversal of cold and warm conditions. In comparison to the North Atlantic oscillation/Arctic Oscillation, the EZ has a more significant influence on the interannual variability of winter and subseasonal reversals. Strong EZ years are associated with the weakening of the Siberian High and the Ural Blocking High, causing the East Asian Trough to move eastward, which leads to the retention of cold air from the north and increased SAT in North China. Conversely, weak EZ years exhibit opposite circulation patterns. The winter mean EZ is influenced by preceding autumn Arctic sea ice concentrations (SIC). Reduced autumn SIC results in decreased heat flux and reduced eddy energy, leading to substantial attenuation of the winter storm track across Scandinavia and Western Asia. This attenuation, mediated through the interaction between eddies and mean flow, triggers a slowdown of Eurasian zonal circulation and intensification of the Siberian High. These conditions favor a positive phase of the winter Scandinavia pattern, facilitating the transport of cold Arctic air into North China. Likewise, subseasonal reversals in SIC influence corresponding alterations in the EZ.

The reanalysis data suggest that recent surface warming over Antarctica start in 2016. In this study, using reanalysis data and numerical simulations, I attempt to determine the important mechanisms accounting for seasonal surface warming in Antarctica. The results suggested that seasonal surface warming in Antarctica is mainly determined by the surface energy budget over the Antarctic via horizontal heat advection. The surface energy budget anomaly over the Antarctic, which is mainly determined by anomalous solar radiation absorption, anomalous ocean heat content, and anomalous meridional atmospheric heat transport (AHT), is triggered by Antarctic sea-ice loss and thus determines the observational seasonality of recent warming in Antarctica via surface horizontal heat advection. In austral summer (December–January–February), additional solar radiation absorption induced by sea-ice loss and additional AHT from lower latitudes increase the energy budget over the Antarctic. Surface warming, more longwave radiation, and additional energy stored in the upper (deeper) ocean for short (long) time periods explain the additional energy sinks. During austral autumn-winter (March–August), additional seasonal heat storage (SHS; mainly stored in the upper ocean) is released to the atmosphere and warms the surface. Although the AHT anomaly contributes similarly to the solar radiation absorption/SHS anomaly during April–August, the poleward AHT largely decreased in June due to the weaker eddy activity induced by strong warming at Southern Hemisphere midlatitudes, which counteracts the additional SHS release and cools the Antarctic(a).

Anvil cirrus generated by deep convection covers large fractions of the tropics and has important impacts on the Earth's radiation budget and climate. In situ measurements made with high-altitude aircraft indicate a rapid transition in ice crystal size distributions and habits as anvil cirrus ages. We use numerical simulations to investigate the impact of high-frequency gravity waves on the evolution of anvil cirrus microphysical properties. The impacts of both monochromatic gravity waves and ubiquitous stochastic mesoscale temperature fluctuations are simulated. In both cases, the interplay between wave-driven temperature fluctuations, deposition growth/sublimation, and sedimentation causes accelerated removal of both small ice crystals (diameters less than about 10 μm) and large crystals (diameters larger than ≈30 μm). These changes are consistent with the observed evolution of anvil cirrus microphysical properties. The Kelvin effect (higher saturation vapor pressure over curved surfaces) is a critical factor in the anvil evolution, driving mass transfer from small to large ice crystals. The wave-driven decrease in ice concentration is much faster for typical anvil cirrus detrained at ≃11.5–12.5 km than for less frequent anvils at 15.5–17.5 km because of the strong temperature dependence of deposition growth and sublimation rates. The simulations also show that waves, along with the Kelvin effect, drive growth of mid-sized (5–20 μm) ice crystals, which is consistent with the observed transition to bullet rosette habits in aging anvil cirrus. We conclude that high-frequency gravity waves, which are generally not resolved in large-scale models, likely have important impacts on anvil cirrus microphysical properties and lifetimes.

To reconstruct the history of organic carbon (OC) aerosol over south-eastern Europe, dissolved organic carbon (DOC) and its 14C signature (DO14C) were investigated along an ice core drilled at the Mount Elbrus (ELB) in Caucasus. In summer, compared to pre-1945 levels, the DOC concentrations increased by 45% after 1960, the mean DO14C depletion in recent ELB ice relative to atmospheric 14CO2 of 32% being attributed to fossil-fuel sources. DO14C content of ice deposited during the bomb-peak era (1955–1980) closely followed atmospheric 14CO2 changes caused by atmospheric nuclear tests, suggesting the living biosphere as the main biogenic source of DOC in summer in this region. ELB data contrast with those previously obtained in summer Alpine (western Europe) ice in which a post-1950 doubling of DOC was observed and attributed to enhanced emissions of organic compounds from vegetation in France. This regional difference is discussed with respect to changes of biogenic organic compound emissions in response to past change of use-land and global warming. ELB data document, for the first time, changes of DOC and DO14C in winter mountain ice showing an increase by 44% of DOC levels associated with a 14C signature being 47% lower than that of atmospheric 14CO2 in ELB ice deposited after 1960. The 14C winter ELB ice record followed atmospheric 14CO2 changes with a delay of ∼3 years, suggesting that remaining emissions from the living biosphere, together with a small contribution from wood burning, are the main biogenic sources of DOC in winter in this region.

Most ecosystems have resistance to soil moisture (SM) deficit, which is termed drought resistance. Drought resistance can be invalid and global terrestrial carbon uptake losses can be aggravated when SM deficit exceeds a critical threshold. However, soil moisture thresholds (SMTs) that detrimentally impact global terrestrial carbon uptake are still unclear. We performed numerical simulations using the Community Earth System Model, and estimated the SMTs by the back propagation neural network method for the years 2004–2014. The SMTs represent the inflection point for vegetation changes from high to low drought resistance phase, and terrestrial carbon uptake losses from low to high rate. Soil moisture-limited ecoregions have higher SMTs than energy-limited ecoregions, indicating the increased vulnerability and sensitivity of SM-limited ecoregions to SM deficit and more easily aggravated terrestrial carbon uptake losses during drought. SMTs varied in different vegetation types and broadleaf deciduous trees displayed the highest SMTs and C3 arctic grasses have lowest thresholds. Humid and high vegetation coverage rate regions have lower thresholds. The SMTs increase with the increase of clay content and the decrease of sand content. In addition, land-atmosphere feedback caused by SM deficit has a large impact on terrestrial carbon uptake and may be one of the main reasons for the aggravation of vegetation carbon uptake losses. Our results provide a unique perspective for investigating the impact of drought on vegetation.

During 26–27 June 2022, mainly influenced by three mesoscale vortices, central-eastern China (particularly for Henan and Shandong) experiences the first widespread torrential rainfall event of the 2022 flood season (maximum 24-hr accumulated precipitation is ∼380.9 mm), resulting in severe social impacts. The three mesoscale vortices form and sustain under favorable background conditions, mainly including a strong upper-level divergence, an intense middle-level warm advection, and a powerful lower-level convergence associated with a low-level jet. Among the vortices, the vortex which forms over Shandong, lasts for ∼9 hr, and makes a much larger contribution than the other vortices to the accumulated precipitation, is defined as the primary vortex. More than a half of the hourly precipitation peaks in this event appear in the life span of the primary vortex, which is closely related to the variations of the vortex in its cyclonic-vorticity and vertical extent. Backward trajectory analysis indicates that air particles originating from the lower troposphere southwest of the primary vortex contribute the most to its formation (∼82.7%). These air particles mainly experience a notable increase in their cyclonic-vorticity due to convergence-related vertical stretching, which directly renders the formation of primary vortex. During the whole life span of the primary vortex, convergence-related vertical stretching is the most favorable factor for its development/sustainment, and the convection-related vertical transport of cyclonic vorticity ranks second; whereas, the horizontal transport is the most detrimental factor. Moisture budget shows that Southeast China is the most important moisture source for this event (accounting for ∼48.9%).

The North Pacific monsoon trough (NPMT) is an imperative large-scale circulation pattern influencing tropical cyclone (TC) activity in the western North Pacific (WNP), thus its future change has great implications for the WNP TC activity. Here future change in the NPMT and its uncertainty are examined by using 35 climate models from Phase six of Coupled Model Intercomparison Project (CMIP6). Due to the El Niño-like sea surface temperature (SST) pattern, the multi-model ensemble (MME) mean projects an eastward extension of the NPMT in the latter half of the 21st century. However, considerable inter-model uncertainty exists in the projection, which is associated with the diversity in the zonal SST gradient across the tropical Pacific. This diversity in the projected SST is largely rooted in the simulated precipitation biases in the tropical Pacific in the historical experiments of CMIP6 models, which can modulate future Pacific SST distribution through the shortwave-SST feedback. This linkage between biases in historical climate and future climate allows us to constrain the projection by using observational data sets. Emergent constraint using observational precipitation data set reduces the projection uncertainty by 48% and projects an eastward extension of the north Pacific NPMT by 6.2°. This eastward extension of the NPMT indicates an eastward migration of TC genesis location, and elongated TC track and thus strengthened TC intensity, suggesting an increased TC-related disaster for residents near the WNP.