Journal of Geophysical Research: Atmospheres最新文献

{"title":"Hot Weather Amplifies the Urban Dry Island Effect, Especially in Wetter Climates","authors":"Sijia Luo,&nbsp;Xihui Gu,&nbsp;Yansong Guan,&nbsp;Lunche Wang,&nbsp;Louise J. Slater,&nbsp;Dongdong Kong,&nbsp;Xiang Zhang,&nbsp;Qian Cao","doi":"10.1029/2024JD043224","DOIUrl":"https://doi.org/10.1029/2024JD043224","url":null,"abstract":"<p>Atmospheric humidity is usually drier in cities than the surrounding rural areas, a phenomenon known as the urban dry island (UDI) effect. However, the response of atmospheric humidity to hot weather in urban versus rural settings remains unknown. Using long-term summer (June–August) observations at 1662 stations over 1961–2020, we find that China is dominated by drying trends in atmospheric humidity (i.e., increasing vapor pressure deficit (VPD)). These drying trends are aggravated on hot days and amplified by urbanization, that is, the UDI effect is stronger in hot weather. This amplification of the UDI effect on hot days is more prominent in humid than in arid regions. Attributions show that the stronger VPD-based UDI effect on hot days is explained by increased contribution of air temperature in southeastern China and specific humidity in northern China. We suggest that adaptations are required to mitigate adverse combined effects of urban heatwaves and UDIs.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Boundary Layer Wind Characteristics of Typhoon Muifa (2022) at Lujiazui, Shanghai Observed by A Ground-Based Doppler Wind Lidar","authors":"Ziyao Sun,&nbsp;Shanghong Wang,&nbsp;Jie Tang,&nbsp;Hui Yu","doi":"10.1029/2024JD042210","DOIUrl":"https://doi.org/10.1029/2024JD042210","url":null,"abstract":"<p>Understanding wind characteristics of the tropical cyclone boundary layer (TCBL) over land is crucial for improving typhoon forecasts and designing wind-resistant structures. This study employs a ground-based Doppler wind radar (DWL) in Lujiazui, Shanghai, to examine the evolution of TCBL wind and turbulence during Typhoon Muifa (2022), focusing on the transition from the periphery to the eyewall. Observations reveal significant changes in wind characteristics, highlighting the eye region's unique features and the complex dynamics of landfalling typhoons. Before Muifa's passage, the horizontal wind speed exhibited a low-level C-shape, with minimum speeds at 100–200 m, deviating from the typical logarithmic increase, due to high friction velocity and urban terrain effects. The vertical wind profile showed alternating updrafts and downdrafts, indicating dynamic turbulence within the TCBL. Turbulent integral length scales for tangential (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mi>v</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${L}_{v}$</annotation>\u0000 </semantics></math>) and radial (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mi>u</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${L}_{u}$</annotation>\u0000 </semantics></math>) winds at 104–208 m were smaller before the typhoon passage than after, with <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mi>u</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${L}_{u}$</annotation>\u0000 </semantics></math> notably less than <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mi>v</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${L}_{v}$</annotation>\u0000 </semantics></math>, reflecting the influence of typhoon rotation and localized shear. Streak and roll intensities revealed intensified turbulence and energy transport near the surface before Muifa's passage, potentially contributing to localized wind damage. These structures exhibited periodic interactions, weakening after the typhoon's passage, likely due to changes in typhoon intensity or structure. Spectral analysis of radial and tangential winds highlighted variations in low-frequency and inertial subrange regions, emphasizing the role of turbulence and scale interactions in modulating energy and momentum transfer. This study demonstrates DWL's effectiveness in detecting fine-scale structures within the TCBL, enhancing understanding of wind and turbulence dynamics during landfalling typhoons.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intercomparison of Machine Learning Models to Determine the Planetary Boundary Layer Height Over Central Amazonia","authors":"Adam Stapleton,&nbsp;Cléo Quaresma Dias-Junior,&nbsp;Celso Von Randow,&nbsp;Flávio Augusto Farias D'Oliveira,&nbsp;Christopher Pöhlker,&nbsp;Alessandro C. de Araújo,&nbsp;Mark Roantree,&nbsp;Elke Eichelmann","doi":"10.1029/2024JD042488","DOIUrl":"https://doi.org/10.1029/2024JD042488","url":null,"abstract":"<p>The planetary boundary layer height (<i>zi</i>) is a key parameter in meteorology and climatology, influencing weather prediction, cloud formation, and the vertical transport of scalars and energy near Earth's surface. This study compares multiple machine learning (ML) models that predict <i>zi</i> from surface measurements at two sites in Central Amazonia—the Amazon Tall Tower Observatory (ATTO) and the Manacapuru site of the GoAmazon experiment (T3). Models were trained on ceilometer data with radiosonde measurements used for validation. We evaluated model performance by withholding approximately 10% of the data (as complete months) for testing, comparing predictions against ERA-5 reanalysis data using <i>RMSE</i>, <i>nRMSE</i>, and <i>R</i>^<i>2</i> metrics. Our results show that gradient boosted ensemble models using all available features perform best. A modified recursive feature elimination algorithm identified minimal sets of 5–7 surface measurements sufficient for accurate <i>zi</i> prediction, demonstrating potential for wider spatial monitoring using cost-effective sensors. The study revealed previously unrecognized variables influential in determining <i>zi</i>, such as deep soil temperature measurements (40 cm), suggesting new avenues for investigating land-atmosphere interactions. This study demonstrates the applicability of ML models to model <i>zi</i>.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042488","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the Directional Derivative Approach for Timely and Accurate Satellite-Based Emission Estimation Using Chemical Transport Model Simulation of Nitrogen Oxides","authors":"Zolal Ayazpour,&nbsp;Kang Sun,&nbsp;Ruixin Zhang,&nbsp;Huizhong Shen","doi":"10.1029/2024JD042817","DOIUrl":"https://doi.org/10.1029/2024JD042817","url":null,"abstract":"&lt;p&gt;The directional derivative approach (DDA) has the potential to rapidly and accurately quantify emission distributions based on the directional derivative of satellite-observed column amounts with respect to the horizontal wind. From the first principles, this paper derives the DDA emission estimators with a range of complexity by vertically integrating the 3D continuity equation and simplifying the results under several assumptions and approximations. The connection and difference between the DDA and a widely used divergence method for emission estimation are highlighted. A key difference is that the DDA integrates from the surface to an intermediate altitude instead of to the top of the observed column. This leads to the inherent background removal of the DDA, in contrast to the explicit background removal necessitated by the divergence method theory. Linear fittings are used to account for the effects of topography, chemical reactions, and retrieval biases. Realistic estimators of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mi&gt;x&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}mathrm{O}}_{x}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; emissions using satellite-observed &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;NO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{NO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; column amounts are proposed, leveraging external climatology of the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mi&gt;x&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}mathrm{O}}_{x}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;:&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}mathrm{O}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; ratio and its directional derivative. These estimators are evaluated within a WRF-CMAQ simulation of &lt;span&gt;&lt;/span&gt;&lt;math","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinct Future Changes and Biases of Tropical Cyclone Activities Between Fully-Coupled and Atmospheric-Only Models in the CMIP6-HighResMIP","authors":"Fang Wang,&nbsp;Leying Zhang,&nbsp;Jiuwei Zhao","doi":"10.1029/2024JD042615","DOIUrl":"https://doi.org/10.1029/2024JD042615","url":null,"abstract":"<p>Most models project a decreasing trend in global tropical cyclone (TC) frequency under future climate scenarios. However, discrepancies in TC activity projection between atmosphere-only and full-coupled models remain unclear. Here, we utilize the CMIP6-HighResMIP data to investigate future changes in TC activity, including TC genesis frequency (TCGF) and track density (TCTD), in response to climate warming and El Niño-Southern Oscillation (ENSO). Results reveal significant variability in TC activity projections between the two modeling approaches, reflecting substantial uncertainties. Fully-coupled models projected an El Niño-like sea surface temperature (SST) warming over the equatorial Pacific, while atmosphere-only models demonstrated a La Niña-like warming pattern. These contrasting SST responses drive diverse atmospheric circulation anomalies, eventually contributing to distinct TCGF and TCTD changes under climatology and during ENSO phases for future projections. Further detailed analysis reveals that the El Niño-like or La Niña-like warming patterns belong to two extreme conditions. It shows a strong spread of simulated SST biases across different models. The accurate projection and simulation of SST magnitudes and ENSO patterns are key to reducing the diverse behaviors of TC activities among these models. We detected three crucial regions, the central Pacific, the subtropical eastern North Pacific, and the equatorial eastern Pacific, that could modulate TC activity in response to ENSO in numerical models. These findings provide critical insights into how global warming and ENSO modulate TC activities, highlighting the importance of model configuration in predicting future TC behavior.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comprehensive Study on the Ice Freeze-Thaw Process in a High-Elevation Large Lake of the Tibetan Plateau","authors":"Xingdong Shi,&nbsp;Binbin Wang,&nbsp;Yaoming Ma,&nbsp;Lijun Sun,&nbsp;Weimo Li,&nbsp; Lazhu,&nbsp;Zeyong Hu,&nbsp;Hongchao Zuo,&nbsp;Xuan Li,&nbsp;Mingsheng Chen","doi":"10.1029/2024JD042750","DOIUrl":"https://doi.org/10.1029/2024JD042750","url":null,"abstract":"&lt;p&gt;Frozen lakes are common across temperate and subarctic zones of the Northern Hemisphere, including the high-elevation inland lake zone of the Tibetan Plateau (TP), where the freeze-thaw processes are rarely studied due to the harsh environment and limited field experiments. This study, using in situ measurements, satellite products, and the Weather Research and Forecasting with lake (WRF-Lake) simulations at Nam Co, TP, investigates under-ice thermodynamics and lake-atmosphere flux exchange by considering ice surface momentum roughness length &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;z&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({mathrm{z}}_{0mathrm{m}}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, solar radiation transmission, and snowfall accumulation. The results indicate that default WRF-Lake simulations reproduce the seasonal variations of ice phenology dynamics and thermal evolution patterns but exhibit excessively slow under-ice warming, premature ice-off, and overestimated sublimation. Eddy covariance (EC) measurements suggest that the typical ice surface &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;z&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{z}}_{0mathrm{m}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; value &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1.65&lt;/mn&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;4&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left(1.65times {10}^{-4}mathrm{m}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is approximately one order of magnitude lower than the default value &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 ","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-Term Variability and Tendencies of the Semidiurnal Tide in Mesosphere and Lower Thermosphere From Meteor Radar Observations Over Esrange (67.9°N, 21.1°E)","authors":"K. Ramesh,&nbsp;Nicholas J. Mitchell,&nbsp;Neil P. Hindley,&nbsp;Tracy Moffat-Griffin","doi":"10.1029/2024JD043134","DOIUrl":"https://doi.org/10.1029/2024JD043134","url":null,"abstract":"<p>Long-term variability and tendencies in monthly mean semidiurnal tide (12-hr) in zonal (U₁₂) and meridional (V₁₂) winds are investigated in northern polar mesosphere and lower thermosphere (MLT; ∼80–100 km) using meteor radar observations during 1999–2022 over Esrange (67.9°N, 21.1°E). The climatological mean of U₁₂ and V₁₂ amplitudes peak (up to ∼35 m/s) in winter (December–February) above ∼90–95 km with secondary maxima in late summer/early autumn (August–September), however the amplitude of V₁₂ is larger than U₁₂. The U₁₂ and V₁₂ exhibit strong interannual variability that varies with altitude and month/season. The responses of U₁₂ and V₁₂ anomalies (from 1999–2003) to solar cycle (SC), Quasi Biennial Oscillation (QBO) at 10 hPa and 30 hPa, El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), ozone (O₃) and carbon dioxide (CO₂) are analyzed using multiple linear regression. From the analysis, significant correlations are found between monthly tidal amplitudes and the above potential drivers, and the correlations vary with altitude and month. The U₁₂ and V₁₂ responses to O₃ are positive and significantly large (∼60–80 m/s/ppmv) below ∼85–90 km in February–March and above ∼95 km in January-March. The tidal response to ENSO is significantly negative during August-October (above ∼90 km) and positive in November-December (above ∼85 km) in both components. The cumulative trend in U₁₂ is positive below ∼93 km and negative above this height peaking at ∼97 km. A positive trend in V₁₂ increases above ∼93 km and maximize at ∼98 km. The significant monthly trends vary with altitude in both tidal components.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD043134","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contrasting Arctic Amplification Response in the Community Earth System Model Large Ensembles and Implications for the North Atlantic Region","authors":"J. B. Arnheim,&nbsp;Y. Peings,&nbsp;G. Magnusdottir","doi":"10.1029/2024JD042490","DOIUrl":"https://doi.org/10.1029/2024JD042490","url":null,"abstract":"<p>The response of the polar jet to climate warming and rapid Arctic change is a leading uncertainty in climate projections and critical to the future of mid-latitude surface weather. Previous studies suggest that CMIP5-6 model projections fall into two groups of either Arctic- or tropically-driven climate change, especially in the North Atlantic. Here, we present distinct warming patterns emerging by the late 21st century between the first two generations of the Community Earth System Model Large Ensemble (CESM-LE) and use daily diagnostics to assess associated changes in mid-latitude circulation. We show that the subsequent versions of CESM represent categorically different storylines of North Atlantic climate change. The first version of CESM-LE (CESM1-LE, hereafter LENS1) exhibits severe Arctic amplification (AA) along with minor reductions in jet waviness. In contrast, CESM2-LE (hereafter LENS2) presents subdued AA, a more pronounced North Atlantic warming hole, and a late-century climate dominated by upper-tropospheric tropical warming. Uniquely, in LENS2 during winter, the North Atlantic sector projects less warming in the Arctic than in the mid-latitude mid-troposphere. The projected North Atlantic jet is reinforced and poleward-shifted with reduced sinuosity, blocking, and synoptic variability. The surface weather response includes greater precipitation over northern Europe, more intense drying in the eastern Mediterranean, and a lesser decline in cold extremes by late century compared to LENS1.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042490","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Similarities in Meteorological Composites Among Different Atmospheric River Detection Tools During Landfall Over Western Coastal North America","authors":"Kwesi T. Quagraine,&nbsp;Travis A. O’Brien,&nbsp;Yang Zhou","doi":"10.1029/2024JD042163","DOIUrl":"https://doi.org/10.1029/2024JD042163","url":null,"abstract":"<p>Many atmospheric river detection tools (ARDTs) have been developed over the past few decades to identify atmospheric rivers (ARs). Different ARDTs have been observed to capture a variety of frequencies, shapes, and sizes of ARs. Due to this, questions have arisen about the underlying phenomena associated with the detected ARs: do all ARDTs detect the same meteorological phenomena? In this paper, we assess eight ARDTs and investigate the underlying synoptic scale phenomena during landfalling ARs along the west coast of North America. We find that during landfalling AR events, prevalent low-pressure and high-pressure systems converge and enhance moisture influx toward the landfalling site. We identify that all eight ARDTs identify AR conditions associated with baroclinic waves, with the region of intense integrated vapor transport (IVT) located downstream of the upper level (500 hPa) trough. The magnitude of IVT is enhanced by the strength of the pressure gradients in the confluence region. Although the ARDTs assessed agree on the general phenomena, there are however subtle differences in each ARDT per the clustering analysis we performed. We conclude that the eight ARDTs identify similar underpinning synoptic scale meteorological phenomena.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042163","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"KAZR-CloudSat Analysis of Snowing Profiles at the North Slope of Alaska: Implications of the Satellite Radar Blind Zone","authors":"J. A. Shates,&nbsp;C. Pettersen,&nbsp;T. S. L’Ecuyer,&nbsp;M. S. Kulie","doi":"10.1029/2024JD042700","DOIUrl":"https://doi.org/10.1029/2024JD042700","url":null,"abstract":"<p>Spaceborne radars provide near-global observations of clouds and precipitation, but ground clutter can result in a satellite radar blind zone as high as 2 km above the surface. As a result, satellite radars may underestimate snowfall from shallow clouds and incorrectly flag snow virga as snowfall at the surface. Ground-based radar observations provide invaluable tools to assess satellite observations of clouds and precipitation. This study investigates snowfall regimes using observations from 2011 to 2021 at the Department of Energy Atmospheric Radiation Measurement North Slope of Alaska atmospheric observatory. Snowfall events identified in the Ka-band ARM zenith radar (KAZR) are separated into regimes based on the cloud/precipitation layer characteristics: deep snowfall, shallow snowfall, and snow virga. The shallow snowfall regime accounts for nearly half of the regime occurrence (48%) followed by snow virga (28%) and deep snowfall (23%). However, more than half (62%) of the shallow snowfall is likely underestimated and/or undetected within the satellite radar blind zone. Snow virga is incorrectly flagged as snowfall for 7% of the total annual occurrence, but increases to 12% in October. The KAZR regimes and vertical structure are qualitatively compared to collocated CloudSat observations with snow certain/possible flags; the deep and shallow snowfall regime show similarities between the ground-based and spaceborne radar observations. An assessment of observable snowfall occurrence and accumulation at varying reflectivity thresholds in KAZR and CloudSat provide a reference for detection characteristics for current and planned spaceborne radars.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}