Atmospheric Research最新文献

{"title":"Local and regional enhancements of GHGs in Thessaloniki, inferred from ground-based FTIR measurements","authors":"Marios Mermigkas ,&nbsp;Chrysanthi Topaloglou ,&nbsp;Dimitrios Balis ,&nbsp;Frank Hase ,&nbsp;Darko Dubravica","doi":"10.1016/j.atmosres.2025.108035","DOIUrl":"10.1016/j.atmosres.2025.108035","url":null,"abstract":"<div><div>Global warming and subsequent climate change are currently a major issue both in the scientific community and the society. Therefore it is highly important to consistently monitor the concentrations of greenhouse gases that affect the incoming-outgoing energy balance. To that end, a portable Bruker EM27/SUN FTIR spectrometer is operated in Thessaloniki, Greece since January 2019, performing measurements of total column-averaged dry air mole fractions of trace gases, denoted as X-gases. In this study, we demonstrate the utility of available measurements of greenhouse gases (GHGs) to identify the origin of enhanced concentrations. Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data are used synergetically with FTIR measurements. XCO₂ shows an obvious annual increase (over 2.2 ppm per year) and a clear seasonal variation with high increased concentrations during cold season and decreased concentration during summer period due to photosynthesis activity. XCH₄ shows an annual increase and a positive trend. The continuous fire episodes in Athens and North Evia during July and August 2021 led to an unprecedented increase in the concentrations of CO of over 130 %, compared to the typical averaged mean values during August in Thessaloniki. In this paper we investigate the seasonal dependency between CO-CO₂ and CO-CH₄ enhancements with respect to the prevailing wind direction and we examine if meteorological parameters, such as wind direction and speed, could reveal the origin of enhanced X-gas variations. We applied two different approaching methods to detect long-term and short-term signals of the trace gases. In general, concerning the FTIR measurements, during summer and autumn XCO₂, XCO and XCH₄ enhancements are observed for low and medium speed winds. Winds mainly originating from SW directions have transported large amounts of CO₂, CO and CH₄ from the big fires near Athens and N. Evia in summer 2021 to Thessaloniki. The fire emissions generate higher variability of the columns of target gases (over 0.022 ppm in the S and SW wind direction).</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"319 ","pages":"Article 108035"},"PeriodicalIF":4.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562627","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":"Characteristics of orographic clouds and associated mechanisms in the Qilian Mountains, northeastern Tibetan Plateau based on FengYun-4A satellite TBB product","authors":"Yi Chang ,&nbsp;Qianrong Ma ,&nbsp;Peng Qi ,&nbsp;Xueliang Guo ,&nbsp;Dawei Lin ,&nbsp;Lijun Guo ,&nbsp;Di Di ,&nbsp;Yang Zhao ,&nbsp;Hui Wang ,&nbsp;Tianyu Chen","doi":"10.1016/j.atmosres.2025.108031","DOIUrl":"10.1016/j.atmosres.2025.108031","url":null,"abstract":"<div><div>The Qilian Mountains (QM) in northwest China is a key source of orographic cloud formation, significantly influencing regional weather, climate, and hydrological balance. However, due to the sparse distribution of ground-based observational stations, the characteristics of orographic clouds and their associated precipitation remain insufficiently understood. Utilizing FengYun-4A black body temperature (TBB) data from 2018 to 2021 in boral summer, this study investigated the spatial and diurnal characteristics of orographic clouds and associated mechanisms over the QM. Results indicate that orographic clouds primarily form over the mountainous terrain, with deep convective clouds concentrated in the central and eastern QM. A distinct diurnal cycle is observed, with peak cloud activity occurring in the afternoon to early evening (15:00–19:00 local solar time), minimal activity late at night, and the weakest development in the morning. These variations are more pronounced in the central and eastern QM, where cloud formation persists for longer durations, compared to the western region. Three dominant diurnal cloud cycles are identified in the southeast, northeast, and eastern fringes of the western, central, and eastern QM, respectively, along with smaller-scale cycles along mountain ridges. Orographic cloud formation is driven by the convergence of low-level westerlies and the Asian monsoon, with moisture contributions from the westerlies, the Tibetan Plateau, and the monsoon system. Additionally, interactions between solar heating and complex terrain shape the spatial and diurnal distribution of these clouds. These findings enhance our understanding of regional water cycles and provide valuable insights for weather and climate research.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"320 ","pages":"Article 108031"},"PeriodicalIF":4.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636867","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":"Observational climatology and interannual variability of the spring rainy season onset over southern China: Objective definition and influence from tropical Pacific Ocean","authors":"Kexu Zhu ,&nbsp;Wen Chen ,&nbsp;Peng Hu ,&nbsp;Yehong Luo ,&nbsp;Ruowen Yang ,&nbsp;Linwei Jiang ,&nbsp;Qingyu Cai ,&nbsp;Lu Gao ,&nbsp;Jingnan Li ,&nbsp;Yongmao Peng ,&nbsp;Changhao Wu ,&nbsp;Ziqi Niu","doi":"10.1016/j.atmosres.2025.108030","DOIUrl":"10.1016/j.atmosres.2025.108030","url":null,"abstract":"<div><div>Based on multiple datasets, the spring rainy season onset (RSO) date over southern China is objectively determined and validated, and the relationship between RSO and tropical Pacific SST is then explored. The RSO date is defined as the time when the cumulative precipitation departure over southern China reaches its minimum value, with a climatological onset date of March 14 and a standard deviation of 22 days. The RSO is closely linked to the sudden changes in atmospheric circulations and abrupt emergence of rainfall and convection, displaying strong interannual variability. An early RSO is characterized by an increase in rainfall during February and March, and is associated with a zonal sea surface temperature (SST) dipole in the tropical Pacific. This is because the concurrent cooler SST in the tropical Western Pacific triggers lower-tropospheric southwesterly wind anomalies over the western North Pacific through Matsuno-Gill-type Rossby wave response. These wind anomalies then enhance water vapor transport and warm advection towards southern China, which, in turn, fosters anomalous upward motion combined with vorticity advection. Such anomalous ascending motion is favorable for the increased precipitation and the advanced RSO over southern China.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"320 ","pages":"Article 108030"},"PeriodicalIF":4.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562133","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":"Two major sudden warming events in the unprecedentedly active stratosphere during the boreal winter of 2023/2024 and their distinct surface impacts over China","authors":"Jincai Xie ,&nbsp;Jinggao Hu ,&nbsp;Xuancheng Li ,&nbsp;Jing-Jia Luo ,&nbsp;Haiming Xu ,&nbsp;Yanpei Jia","doi":"10.1016/j.atmosres.2025.108032","DOIUrl":"10.1016/j.atmosres.2025.108032","url":null,"abstract":"<div><div>In the boreal winter of 2023/2024, the 10-hPa stratosphere experienced unprecedented planetary wave activity. This led to two major sudden stratospheric warming (SSW) events occurring on January 16 and March 4. The onset processes of both SSWs demonstrated clear stratosphere-troposphere coupling. On one hand, notable precursor signals were detected in the troposphere before each SSW. Approximately 15 days prior to the first SSW, a markedly intensified 500-hPa high pressure emerged over the high-latitude Atlantic, resulting in the strongest wave 3 in the troposphere since 1979. Additionally, an anomalous high over eastern Europe served as a precursor signal for the second SSW, contributing to a rapid increase in waves 1 and 2 approximately 20 days before its occurrence. On the other hand, these two SSWs exhibited distinct impacts on subsequent surface air temperature (SAT) over China. Specifically, the first SSW was characterized as a reflecting event. Following its onset, strong planetary wave reflections were observed in the troposphere over the Siberian and North Pacific regions, leading to local high-pressure ridge development. The two ridges, along with troughs between them, created an “inverted Ω-shaped” circulation pattern and caused a cold wave across China during January 18–22. In contrast, the second SSW was identified as an absorbing event; its impact aligned with typical effects of SSWs on SAT over Eurasia. After its onset, a negative phase of Northern Annular Mode emerged in the stratosphere and propagated downward into the troposphere over time, resulting in warming conditions over China during the following month.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"319 ","pages":"Article 108032"},"PeriodicalIF":4.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552726","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":"Radar characteristics of seeded and unseeded hail clouds in Romania","authors":"Vasilică Istrate PhD ,&nbsp;Serghei Eremeico Eng. ,&nbsp;Lucian-Ionuț Lazăr Eng. ,&nbsp;Dragoș Andrei Sîrbu Eng. ,&nbsp;Eduard Popescu ,&nbsp;Emil Sîrbu PhD ,&nbsp;Doru Dorian Popescu Eng.","doi":"10.1016/j.atmosres.2025.108028","DOIUrl":"10.1016/j.atmosres.2025.108028","url":null,"abstract":"<div><div>This study evaluates the effectiveness of silver iodide (AgI) cloud seeding in Romania by comparing radar-derived parameters of 20 seeded and 20 unseeded severe hailstorms observed between 2017 and 2022. Radar data from S and C-band systems were analyzed using six key parameters, including maximum reflectivity (Zmax), vertically integrated liquid (VIL), Volume of the cloud with reflectivity more than 35 dBZ (dV35) and height of the 45dBZ echo above the environmental melting level (dH45). Statistical comparisons were conducted using the Mann-Whitney <em>U</em> test to identify significant differences between the two storm groups. The results reveal statistically significant differences in radar metrics between seeded and unseeded storms, with seeded storms generally exhibiting lower parameter values. For instance, median Zmax was 58 dBZ for seeded storms compared to 60 dBZ for unseeded storms, while VIL medians were 19 kg/m² and 27 kg/m², respectively. Similarly, dV35 was reduced by approximately 22 % in seeded storms. These differences indicate that seeding modifies storm microphysical processes and dynamics, potentially suppressing hail formation. However, variability across storm environments and radar categories highlights some uncertainties. Natural fluctuations in convective processes and challenges in tracking seeding agent dispersion complicate the interpretation of results. Nonetheless, the statistical significance of observed differences supports the hypothesis that AgI seeding influences storm characteristics. This study provides quantitative and statistical evidence of seeding effect and underscores the need for further research using advanced radar technologies and larger datasets to refine hail suppression methodologies.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"320 ","pages":"Article 108028"},"PeriodicalIF":4.5,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562132","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":"Responses of atmospheric inorganic nitrogen deposition to emissions in a polluted region of southern China","authors":"Zhi-Li Chen ,&nbsp;Yan Qiu ,&nbsp;Wei Song ,&nbsp;Xue-Yan Liu","doi":"10.1016/j.atmosres.2025.108026","DOIUrl":"10.1016/j.atmosres.2025.108026","url":null,"abstract":"<div><div>Human-induced nitrogen (N) emissions have enhanced atmospheric N deposition in many polluted regions. However, the spatiotemporal relations between N emissions and deposition remain poorly characterized, which hampers N emission management and effect evaluation in polluted regions. This study investigated dry and wet inorganic N (IN) deposition at representative urban and suburban sites from June 2018 to May 2019 and analyzed historical N emission and deposition data in a N-polluted region of southern China. Dry, wet, and total IN deposition were 14.1 and 6.3, 36.4 and 29.0, and 50.5 and 35.3 kg N ha⁻¹ yr⁻¹ at the urban and suburban sites, respectively. Gaseous N accounted for 79–87 % of dry IN deposition and dry deposition accounted for 18–28 % of total IN deposition. The inter-annual variation of wet IN deposition exhibits an inverted “V” shape: the turning point for ammonium (NH₄⁺) was in 1991 due to the decline in the ratio of ammonia to sulfur dioxide and nitrogen oxide and ammonia emissions; nitrate (NO₃⁻) peaked in 2010, reflecting the benefits of national controls on nitrogen oxide emissions. Consequently, a shift to approximately equal NH₄⁺ and NO₃⁻ deposition occurred in 2010–2020. Spatially, annual IN deposition increased with human-induced land use and N emissions, and about 30 % of the area exceeded the critical load for N deposition. Current emission controls are reducing N emissions and deposition but further mitigation measures are needed, especially broader regional strategies.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"319 ","pages":"Article 108026"},"PeriodicalIF":4.5,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552727","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":"Higher-resolution data improves deep learning-based precipitation nowcasting","authors":"Aofan Gong,&nbsp;Bu Li,&nbsp;Ruiyang Zhou,&nbsp;Fuqiang Tian,&nbsp;Guangheng Ni","doi":"10.1016/j.atmosres.2025.108010","DOIUrl":"10.1016/j.atmosres.2025.108010","url":null,"abstract":"<div><div>Accurate and fine-grained precipitation nowcasting holds paramount importance for weather-dependent decision-making and is facing escalating expectations and challenges. While researchers have notably advanced precipitation nowcasting using deep learning (DL) models with larger sizes and more complicated structures, there is scarce research exploring the potential improvement from employing radar data with higher spatial resolutions—a hundred-meter scale rather than a kilometer scale. To evaluate the improvement of higher-resolution data, two U-Net architecture-based models, one larger and another smaller, were designed and trained with radar data at different spatial resolutions—1000 m, 500 m, and 100 m. Their effectiveness was examined by comparison to two baseline models. The models trained with diverse resolutions of data underwent comparative evaluation through two specific precipitation cases. The results unveil a positive correlation between the precipitation nowcasting performance and the spatial resolution of radar data. Models trained with higher-resolution data demonstrate superior forecasting accuracy, reduced bias, and enhanced spatial alignment between predictions and observations. Higher-resolution data empowers DL models to capture boundaries and local-scale patterns of convective systems more accurately, thereby improving the performance in precipitation nowcasting. More importantly, the comparison indicates that to further promote the performance of DL-based precipitation nowcasting, improving data resolution is more efficient than expanding model size. The use of high-resolution data diminishes computational and development costs by concurrently reducing the size of DL models, underscoring pragmatic benefits for related services. Given limited resources, employing higher-resolution data is recommended for priority consideration over larger-size models.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"319 ","pages":"Article 108010"},"PeriodicalIF":4.5,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552725","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":"Simulation of premonsoon thunderclouds over two climatic regimes: evaluation and dichotomous detection","authors":"Rupraj Biswasharma ,&nbsp;Imlisunup Pongener ,&nbsp;Imolemba Longkumer ,&nbsp;G.Ch. Satanarayana ,&nbsp;Sunil D. Pawar ,&nbsp;V. Gopalakrishnan ,&nbsp;Sanjay Sharma","doi":"10.1016/j.atmosres.2025.108027","DOIUrl":"10.1016/j.atmosres.2025.108027","url":null,"abstract":"<div><div>This study investigates premonsoon (April) thundercloud properties over Northeastern (Kohima, 25.6°N, 94.1°E) and Eastern (Rampurhat, 24.2°N, 87.8°E) India. Thunderclouds were detected using Electric Field Mills (EFM-100) and Lightning Detectors (LD-350), while the WRF model was employed to simulate thundercloud properties. Simulations were performed across all 30 days in each region, regardless of actual thundercloud occurrence, to assess the model's accuracy in differentiating thundercloud and non-thundercloud days. The regional variability of cloud-to-ground (CG) flash density was well represented by the model, with higher flash densities in Rampurhat (mean: 39 × 10⁻⁴ km⁻² h⁻¹) compared to Kohima (mean: 31 × 10⁻⁴ km⁻² h⁻¹), consistent with observations. However, the model exhibited a slight overestimation in Kohima and an underestimation in Rampurhat, with spatiotemporal deviations from observations in both regions. Despite this, the simulations effectively captured regional differences in dynamical parameters (vertical velocity, wind shear) and microphysical properties (mixing ratios: q_ice, q_graupel, q_cloud), with Rampurhat showing higher values overall. Six stability indices were evaluated to determine the most reliable indicator for distinguishing thundercloud/non-thundercloud days. In Kohima, the TT index (≥ 38 °C) was most effective, while in Rampurhat, CAPE (≥ 1680 J kg⁻¹) proved more suitable, suggesting that distinct physical mechanisms drive thundercloud development in these regions. The dichotomous detection results for all 30 days in Kohima (Rampurhat) yielded 14 (21) successful detections, 5 (1) misses, 3 (1) false alarms, and 8 (7) correct rejections. We introduced the Correct Rejection Rate (CRR) to assess the model's performance in detecting non-thundercloud days, which showed better accuracy over Rampurhat than Kohima. The study underscores the heightened complexity of predicting thunderclouds over the hilly terrain of Northeastern India compared to the flatter terrain of Eastern India and offers valuable insights for improving strategies to mitigate lightning hazards.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"320 ","pages":"Article 108027"},"PeriodicalIF":4.5,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143575548","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":"Interannual climate anomalies modulate the subseasonal dynamical prediction skill from the regional perspective over Central Southwest Asia","authors":"Shiyu Zhang ,&nbsp;Jing Yang ,&nbsp;Tao Zhu ,&nbsp;Qing Bao","doi":"10.1016/j.atmosres.2025.108023","DOIUrl":"10.1016/j.atmosres.2025.108023","url":null,"abstract":"<div><div>The El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD), as key oceanic boundary conditions, play a pivotal role in modulating regional climate variability. However, their influence on subseasonal dynamical prediction has yet to be fully understood. Focusing on Central Southwest Asia (CSWA), a region urgently needing accurate subseasonal prediction and significantly influenced by ENSO and IOD, this study investigates whether and how these interannual climate anomalies affect regional subseasonal rainfall prediction skills during early boreal winter using state-of-the-art Subseasonal-to-Seasonal (S2S) prediction models. First, the study finds that both deterministic and probabilistic prediction skills for domain-averaged rainfall anomalies and dry/wet events at a 2–4-week lead are significantly enhanced under La Niña and active IOD conditions compared to neutral states, while El Niño conditions show limited enhancement. This asymmetry in the ENSO impact is attributed to the inherent uncertainty in El Niño's influence on CSWA rainfall. Second, the analysis reveals that currently operational models exhibit higher skill in predicting ENSO at a 1-month lead, whereas predictions for IOD are comparatively less accurate. Nonetheless, prediction errors for both strong ENSO and IOD events at a 1-month lead are found to be significantly correlated with rainfall anomaly prediction errors over CSWA during the early boreal winter. This study confirms the significant effect of oceanic boundary conditions on regional subseasonal dynamical predictions and emphasizes the need to improve subseasonal prediction skills related to sea surface temperature variability associated with ENSO and IOD in order to reduce rainfall forecast errors and enhance the reliability of S2S predictions.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"319 ","pages":"Article 108023"},"PeriodicalIF":4.5,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143528686","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":"Impact of snow cover on the surface energy balance and its contribution to the extreme cold wave in Spain after snowstorm Filomena","authors":"Pablo Fernández-Castillo ,&nbsp;Carlos Román-Cascón ,&nbsp;Carlos Yagüe","doi":"10.1016/j.atmosres.2025.108015","DOIUrl":"10.1016/j.atmosres.2025.108015","url":null,"abstract":"<div><div>Snow cover can significantly alter the energy fluxes that take part on the surface energy balance (SEB), which subsequently affects surface air temperature. However, studies of the influence of snow cover on the SEB are scarce due to limited observational data and usually constrained to high altitudes or mountainous areas. In this study, the SEB is analysed under two differentiated land surface conditions: with and without snow cover, for a non-mountainous region in the midlatitudes. This is done in order to analyse the physical processes leading to one of the most extreme and disruptive cold waves of the present century in Spain. The cold wave took place in January 2021 after historical snowstorm Filomena left widespread snowfall amounts of 30–50 cm in the interior of Spain. By means of analysis of in-situ observational data from a micrometeorological tower and synoptic fields, we determine the contribution of synoptic and microscale processes to the extremely cold surface air temperatures recorded. The SEB analysis reveals the decisive role of snow cover in the cold wave. Surface albedo increased from 20 % to 80 %, leading to a 60 % decrease in the surface net radiative flux. Together with weak turbulence conditions due to weak synoptic forcing, this allowed extraordinarily low surface air temperatures. Thus, this event stands out from the typical pattern leading to cold waves in this region, characterised by cold air advection. This study highlights the importance of having observational data of micrometeorological variables, which have proven very insightful into the physical mechanisms contributing to the cold wave.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"320 ","pages":"Article 108015"},"PeriodicalIF":4.5,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562134","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}