Atmospheric Research最新文献_第4页

Surface temperature assimilation improving geostationary meteorological satellite surface-sensitive brightness temperature simulations over land 地表温度同化改进地球静止气象卫星陆地表面敏感亮度温度模拟

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-26 DOI: 10.1016/j.atmosres.2024.107706

This study explores a possibility of improving Advanced Himawari Imager (AHI) surface-sensitive brightness temperature (TB) simulations over land by assimilating land surface temperature (LST) observations from the National Basic Meteorological Observing Stations of China. The Gridpoint Statistical Interpolation 3D-Var regional data assimilation (DA) system is modified to add LST as a new control variable and its background error variances, horizontal correlations and cross-correlations. The background covariances of LST with other control variables are calculated separately for daytime and nighttime samples in summer and winter seasons. A control experiment (ExpCTL) and three LST DA experiments with (ExpLST) and without (ExpLST_NBC) bias correction or with an average of LST within 2° × 2° grid boxes (ExpLST_SO) are conducted. Considering the fact that surface station observations are point measurements while the satellite TBs measure the total radiation effect of earth's surface within fields-of-view, a bias correction is found necessary for LST DA during daytimes (ExpLST). The biases are quantified by the differences from the Moderate-resolution Imaging Spectroradiometer LST retrievals to compensate for the representative differences. The analyzed fields are then used as input to the Community Radiative Transfer Model to simulate TBs of AHI surface-sensitive channels over land. A long-period statistics shows that ExpLST significantly reduces the observations minus simulations (OB) biases and standard deviations of surface-sensitive TBs in terms of reducing the diurnal variations and season dependences of TB biases over different surface types, which also outperforms ExpLST_NBC and ExpLST_SO at daytime. This study suggests a potential benefit of combining the use of LST observations for assimilating surface-sensitive infrared TBs.

本研究探讨了通过同化中国国家基本气象观测站的陆地表面温度（LST）观测资料来改进高级向日葵成像仪（AHI）陆地表面敏感亮度温度（TB）模拟的可能性。对网格点统计插值 3D-Var 区域数据同化（DA）系统进行了修改，增加了 LST 作为新的控制变量及其背景误差方差、水平相关性和交叉相关性。分别计算了夏季和冬季白天和夜间样本的 LST 与其他控制变量的背景协方差。进行了一次对照实验（ExpCTL）和三次 LST DA 实验，分别进行了（ExpLST）和（ExpLST_NBC）偏差校正，或对 2°×2° 网格框内的 LST 进行了平均（ExpLST_SO）。考虑到地面站观测是点测量，而卫星 TB 测量的是视场内地球表面的总辐射效应，因此有必要对白天的 LST DA 进行偏差校正（ExpLST）。偏差通过中分辨率成像分光仪 LST 检索的差异进行量化，以补偿代表性差异。然后，将分析后的场作为共同体辐射传输模式的输入，模拟陆地上 AHI 地表敏感信道的 TB。长周期统计结果表明，ExpLST 在减少不同地表类型 TB 偏差的昼夜变化和季节依赖性方面，显著降低了地表敏感 TB 的观测值减去模拟值（OB）偏差和标准偏差，在白天的表现也优于 ExpLST_NBC 和 ExpLST_SO。这项研究表明，结合使用 LST 观测来同化地表敏感红外 TBs 有潜在的好处。

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引用次数: 0

TEDR: A spatiotemporal attention radar extrapolation network constrained by optical flow and distribution correction TEDR：受光流和分布校正制约的时空注意力雷达外推网络

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-26 DOI: 10.1016/j.atmosres.2024.107702

In recent years, deep learning has been widely applied to meteorological radar extrapolation due to the shortcomings of traditional optical flow methods in predicting the genesis and dissipation of radar echoes. However, it still faces challenges in addressing issues of clarity and overall intensity attenuation caused by uncertainty. This study implemented a dual-path spatiotemporal attention network that integrates optical flow techniques by employing intra-frame static attention and inter-frame dynamic attention, which could simulate motion fields and the overall intensity distribution of radar echoes separately. Our approach effectively resolve the issues of systematic intensity attenuation and clarity degradation introduced by deep learning methods. Through the comparisons of key metrics such as MSE, SSIM, CSI20, CSI30, and CSI40, the results demonstrated significant improvements over traditional approaches, particularly in CSI30 and CSI40, where the metrics improved by more than 35 %.

近年来，由于传统光流方法在预测雷达回波成因和消散方面存在缺陷，深度学习被广泛应用于气象雷达外推。然而，它在解决不确定性导致的清晰度和整体强度衰减问题上仍面临挑战。本研究利用帧内静态关注和帧间动态关注，实现了一种集成光流技术的双路径时空关注网络，可分别模拟运动场和雷达回波的整体强度分布。我们的方法有效解决了深度学习方法带来的系统强度衰减和清晰度下降问题。通过对 MSE、SSIM、CSI20、CSI30 和 CSI40 等关键指标的比较，结果表明与传统方法相比，我们的方法有了显著改进，尤其是在 CSI30 和 CSI40 方面，指标提高了 35% 以上。

引用次数: 0

The source, transport, deposition and direct radiative effect of mineral dust over western China: A modeling study of July 2022 with focus on the Tibetan Plateau 中国西部矿尘的来源、输送、沉积和直接辐射效应：以青藏高原为重点的 2022 年 7 月模拟研究

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-26 DOI: 10.1016/j.atmosres.2024.107708

A Regional Air Quality Model System (RAQMS) driven by WRF was applied to explore the emission, transport, deposition, and direct radiative effect of mineral dust over western China in July 2022, with focus on the Tibetan Plateau (TP). Model validation against ground and satellite observations demonstrated the model reproduced meteorological variables, PM₁₀ concentration, aerosol optical depth (AOD), and extinction coefficients in the vertical reasonably well. There was a dust event during 3–7 July 2022, which was originated from the Taklimakan Desert (TKD) and affected eastern and central TP under anticyclonic flows, resulting in the maximum hourly PM₁₀ concentration exceeding 50 μg m⁻³ in Lhasa. Shortwave radiation was reduced considerably by dust aerosols over eastern TP, with the maximum decrease in daytime mean shortwave radiation reaching 30 W m⁻² around Nyingchi on 5 July. Anthropogenic aerosols dominated PM₁₀ mass in the capital cities of western China (54–67 %), while dust aerosols were dominant in the cities near the deserts. During this dust event, dust aerosols from TKD and Qaidam Desert (QDD) significantly influenced eastern TP, with dust contributions to PM₁₀ mass concentration of 52 %, 76 % and 69 %, respectively, in Chamdo, Lhasa and Nyingzhi, respectively. The total dust emission in western China was about 10.6 Tg in July 2022, with the largest contribution from TKD (63.5 %), followed by Gobi Desert (GB) (26 %). The total deposition of dust was estimated to be 6.2 Tg, in which TKD and GB contributed 66 % and 22 %, respectively. During the study period, about 418 Gg dust aerosols were deposited on TP, 49 % of which was from TKD and 25 % from QDD. Foreign dust sources contributed approximately 7 % and 9 % to dust concentration and total deposition over TP, respectively. Over southern TP, the source contribution to dust deposition was estimated to be 42 %, 24 % and 21 % from TKD, foreign sources and QDD, respectively, suggesting potentially important impact of long-range transboundary dust transport on deposition, surface albedo and climate over TP.

应用由 WRF 驱动的区域空气质量模式系统（RAQMS）探讨了 2022 年 7 月中国西部矿尘的排放、传输、沉积和直接辐射效应，重点是青藏高原（TP）。根据地面和卫星观测资料对模型进行的验证表明，模型较好地再现了气象变量、可吸入颗粒物（PM10）浓度、气溶胶光学深度（AOD）和垂直方向的消光系数。2022 年 7 月 3 日至 7 日，塔克拉玛干沙漠（Taklimakan Desert，TKD）发生了一次沙尘事件，在反气旋流的作用下影响了西藏东部和中部，导致拉萨的 PM10 最大小时浓度超过 50 μg m-3。沙尘气溶胶使大埔东部地区的短波辐射大大减少，7 月 5 日，宁池附近白天平均短波辐射的最大降幅达到 30 W m-2。在中国西部省会城市，人为气溶胶在 PM10 质量中占主导地位（54-67%），而在靠近沙漠的城市，尘埃气溶胶则占主导地位。在这次沙尘事件中，来自塔克拉玛干沙漠和柴达木沙漠（QDD）的沙尘气溶胶对东部TP产生了显著影响，在昌都、拉萨和宁孜，沙尘对PM10质量浓度的贡献率分别为52%、76%和69%。2022 年 7 月，中国西部的沙尘排放总量约为 10.6 吨，其中塔克拉玛干沙漠的贡献最大（63.5%），其次是戈壁滩（26%）。据估计，沙尘的总沉降量为 6.2 吨，其中塔克拉玛干沙漠和戈壁滩分别占 66% 和 22%。在研究期间，约有 418 千兆克的尘埃气溶胶沉积在大埔县，其中 49% 来自塔克拉玛干沙漠，25% 来自丘陵沙漠。外来尘源分别约占大埔区尘埃浓度和总沉降量的 7% 和 9%。在南部大埔，估计尘埃沉降的来源分别为 42%、24% 和 21%，分别来自倒扣湾、外国来源和 QDD，这表明远距离越境尘埃迁移可能对大埔的沉降、地表反照率和气候产生重要影响。

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引用次数: 0

PreciDBPN: A customized deep learning approach for hourly precipitation downscaling in eastern China PreciDBPN：中国东部降水小时降尺度的定制化深度学习方法

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-25 DOI: 10.1016/j.atmosres.2024.107705

Long-term series of high-resolution gridded precipitation datasets are essential for hydrological and meteorological research. Producing high-resolution precipitation data from regional models demands substantial computational resources and labor. Global Reanalyses offer long-term coverage and effectively capture annual and seasonal precipitation patterns. However, they have inadequate resolution and frequently have difficulties depicting extreme conditions. This study proposes an efficient and accurate approach for generating long-term series of high spatial and temporal resolution precipitation. It is achieved by leveraging deep learning techniques to integrate the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) global climate reanalysis (ERA5, 0.25°, hourly) data with high-resolution precipitation fusion datasets. Considering the heavy-tailed distribution of precipitation, we developed the PreciDBPN model structure, which combines a classification network with a super-resolution network and incorporates physically relevant indices into the model's input. We trained and evaluated the PreciDBPN and baseline models in eastern China using the China Meteorological Administration Land Data Assimilation System (CLDAS) precipitation dataset (0.0625°, hourly, 2017–2022). When compared to baseline methods and ERA5, our model excels in multiple metrics and provides a more precise representation of relative rainfall frequency. Independent verification was performed using station observations during the period of 2010–2015 when CLDAS data were unavailable. During this verification, the PreciDBPN demonstrated exceptional performance and greater robustness compared to the baseline models. Because our method can efficiently downscale precipitation and bias-correct reanalysis data using minimal computational resources, it can be used to generate high-resolution precipitation datasets (0.0625°, hourly) from 1979 to 2022 while correcting for heavy precipitation underestimations in reanalysis data.

长期系列的高分辨率网格降水数据集对水文和气象研究至关重要。从区域模式中生成高分辨率降水数据需要大量的计算资源和人力。全球再分析可提供长期覆盖范围，并有效捕捉年度和季节降水模式。然而，它们的分辨率不足，经常难以描绘极端条件。本研究提出了一种高效、准确的方法，用于生成高时空分辨率降水的长期序列。该方法利用深度学习技术，将欧洲中期天气预报中心（ECMWF）第五代全球气候再分析（ERA5，0.25°，每小时）数据与高分辨率降水融合数据集整合在一起。考虑到降水的重尾分布，我们开发了 PreciDBPN 模型结构，它将分类网络与超分辨率网络相结合，并将物理相关指数纳入模型输入。我们利用中国气象局陆地数据同化系统（CLDAS）降水数据集（0.0625°，每小时，2017-2022年）在中国东部对PreciDBPN和基线模式进行了训练和评估。与基线方法和ERA5相比，我们的模型在多个指标上都更胜一筹，并能更精确地表示相对降雨频率。在 2010-2015 年期间，由于 CLDAS 数据不可用，我们使用观测站观测数据进行了独立验证。在验证过程中，与基线模型相比，PreciDBPN 表现出了卓越的性能和更强的鲁棒性。由于我们的方法可以利用最少的计算资源有效地降低降水尺度并对再分析数据进行偏差校正，因此可用于生成从 1979 年到 2022 年的高分辨率降水数据集（0.0625°，每小时），同时校正再分析数据中被低估的强降水。

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引用次数: 0

Thermal effect of the Southeast Asian low-latitude highlands on interannual variability in the date of the Bay of Bengal summer monsoon onset 东南亚低纬度高原对孟加拉湾夏季季风开始日期年际变化的热效应

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-25 DOI: 10.1016/j.atmosres.2024.107709

The timing of the Bay of Bengal summer monsoon (BOBSM) onset has implications for the evolution of the Asian summer monsoon and associated precipitation. This study employs Japanese 55-year Reanalysis and NOAA's Gridded Precipitation Reconstruction over Land data to explore the spatiotemporal variation in the thermal influence of the Southeast Asian low-latitude highlands (SEALLH) and its effect on the BOBSM onset date. There is a significant correlation between pre-monsoon season (February–April) shortwave radiative heating (SWH) in the SEALLH and BOBSM onset in the interannual time scale. During the enhanced SWH, an anomalous vertical circulation, which converges and ascends in the lower troposphere over the SEALLH and converges and descends in the upper troposphere north of the Bay of Bengal (BOB), develops over the SEALLH–north of BOB during the pre-monsoon season with anticlockwise rotation. The warmer air mass resulting from the adiabatic heating is accumulated around the north of BOB by the insulation effect related to the anomalous vertical circulation. By facilitating the reversal of the land-sea thermal contrast, the warmer upper troposphere over the north of the BOB causes a 16-day earlier onset of the BOBSM than the case of weakened SWH. The findings shed light on subsequent research into the thermal effects of the SEALLH on Asian summer monsoon variability.

孟加拉湾夏季季风（BOBSM）开始的时间对亚洲夏季季风和相关降水的演变有影响。本研究利用日本 55 年再分析和 NOAA 的陆地网格降水重建数据，探讨了东南亚低纬度高地（SEALLH）热影响的时空变化及其对孟加拉湾夏季季风开始时间的影响。在年际时间尺度上，季风季节前（2 月至 4 月）东南亚低纬度高原短波辐射加热（SWH）与京承地震发生时间之间存在明显的相关性。在增强的 SWH 期间，孟加拉湾季前的对流层对流层东南部和对流层东南部以北的对流层对流层对流层对流层对流层东南部和对流层东南部以北形成了异常垂直环流，该环流在对流层低层汇聚并上升，在对流层高层汇聚并下降，并呈逆时针旋转。绝热加热产生的较暖气团通过与异常垂直环流有关的隔热效应积聚在孟加拉湾北部周围。由于促进了海陆热对比的逆转，BOB 北部较暖的对流层上部比 SWH 减弱的情况下提前 16 天开始出现 BOBSM。这些发现为随后研究东南暖流对亚洲夏季季风变率的热效应提供了启示。

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引用次数: 0

Extreme wildfires over northern Greece during summer 2023 – Part A: Effects on aerosol optical properties and solar UV radiation 2023 年夏季希腊北部上空的极端野火 - A 部分：对气溶胶光学特性和太阳紫外线辐射的影响

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-22 DOI: 10.1016/j.atmosres.2024.107700

In Mediterranean countries, such as Greece, the frequency of forest fires has increased in recent years, primarily due to the widespread impacts of climate change. At the end of August 2023, Greece experienced a record-breaking heatwave that triggered severe wildfire incidents, significantly impacting the atmospheric conditions of several cities, among them Thessaloniki. A significant number of wildfires occurred in northern Greece (Evros), burning thousands of hectares of the protected Dadia forest (Natura 2000) and releasing a significant load of smoke into the atmosphere. According to the European Strategy Forum on Research Infrastructures (ESFRI) a total area of 90,000 ha was burnt collectively by the Evros extreme wildfires during August 2023. The emissions led to severely adverse air pollution conditions, causing reduced visibility across an extended eastern Mediterranean region for several days. In this work, we analyze the influence of the transported biomass burning particles on the aerosol properties in the free troposphere, as well as on the surface UV radiation levels over Thessaloniki during the last week of August 2023. The transported smoke plume was detected over the Laboratory of Atmospheric Physics (LAP) in Thessaloniki, approximately 240 km away from the burning area, from August 22nd to the 25th. During this period, the presence of smoke led to exceptionally increased levels of aerosol optical depth (AOD), reaching up to 3.4 at 340 nm (the highest ever recorded in Thessaloniki), as well as high Ångström exponent (AE) values, peaking at 2.4 for the 440–870 nm range, followed by high Fine Mode Fractions (FMFs), indicating the prevalence of fine-mode smoke aerosol particle. Moreover, during the event, the presence of the biomass burning aerosols led to a strong attenuation of the solar UV irradiance by up to 90 %, reaching unprecedented levels, similar of a solar eclipse. The primary goal of this study is to highlight the extensive impacts that wildfires have, which are anticipated to increase in frequency in the near future, due to the predicted rise in the rate of occurrence of summer heatwaves especially for Mediterranean areas and specifically for Greece. Furthermore, the great value of the synergistic monitoring of the event with ground-based remote sensing instrumentation, along with satellite aerosol observations and modeling tools, is made prominent.

在希腊等地中海国家，森林火灾的发生频率近年来有所上升，主要原因是气候变化的广泛影响。2023 年 8 月底，希腊经历了破纪录的热浪，引发了严重的野火事件，对几个城市的大气状况造成了严重影响，其中包括塞萨洛尼基。希腊北部（埃夫罗斯）发生了大量野火，烧毁了数千公顷受保护的达迪亚森林（自然保护 2000），并向大气中释放了大量烟雾。根据欧洲研究基础设施战略论坛（ESFRI）的数据，2023 年 8 月埃夫罗斯极端野火共烧毁了 90,000 公顷的土地。这些排放物导致了严重的空气污染状况，使地中海东部地区的能见度连续数天下降。在这项工作中，我们分析了 2023 年 8 月最后一周生物质燃烧颗粒物的迁移对自由对流层气溶胶特性以及塞萨洛尼基上空地表紫外线辐射水平的影响。8 月 22 日至 25 日，在距离燃烧区约 240 公里的塞萨洛尼基大气物理实验室（LAP）上空检测到了烟羽飘移。在此期间，烟雾的存在导致气溶胶光学深度（AOD）水平异常升高，在 340 纳米波长处高达 3.4（这是塞萨洛尼基有记录以来的最高值），Ångström 指数（AE）值也很高，在 440-870 纳米波长范围内达到峰值 2.4，其次是细模式分数（FMF）很高，表明细模式烟雾气溶胶粒子很普遍。此外，在事件发生期间，生物质燃烧气溶胶的存在导致太阳紫外线辐照度强烈衰减达 90%，达到前所未有的水平，类似于日食。这项研究的主要目的是强调野火的广泛影响，由于预计夏季热浪的发生率会上升，特别是对地中海地区，尤其是希腊，因此预计野火在不久的将来会更加频繁。此外，利用地面遥感仪器以及卫星气溶胶观测和建模工具对事件进行协同监测的巨大价值也十分突出。

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引用次数: 0

Disentangling the effects of meteorology and emissions from anthropogenic and biogenic sources on the increased surface ozone in Eastern China 厘清气象、人为和生物源排放对华东地区地表臭氧增加的影响

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-21 DOI: 10.1016/j.atmosres.2024.107699

China's Clean Air Actions have substantially improved ambient PM_2.5 air quality since 2013. However, ozone (O₃) pollution in urban areas has worsened in recent years, particularly in the eastern region. The formation of O₃ in these high emission areas is highly complex and regulated by numerous factors. Utilizing the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), this study conducted a comprehensive analysis through nine sensitivity experiments for the years 2013 and 2017, aimed at disentangling the relative contributions of major factors (e.g., meteorological factors, anthropogenic emissions, biogenic emissions, and aerosol feedback mechanisms) to the observed O₃ concentration trends in Jiangsu, a developed region of China with increasing trend of O₃ level. Our findings indicate a pronounced increase in mean daily maximum 8-h average (MDA8) O₃ levels in the economically vibrant southern Jiangsu, contrasted with a decrease in the less developed northern regions. The study identifies anthropogenic emissions change as the primary driver of O₃ variations, with significant impacts also attributed to meteorological conditions and aerosol feedback effects, while biogenic emission shifts play a lesser role. In terms of meteorological factors, we discovered that the alteration in meteorological thermal factors (enhanced solar radiation and temperatures) in 2017, compared to 2013, exerted a more pronounced influence on the formation of O₃ than the change in thermally driven dynamic factors (boundary layer height and wind speed). Moreover, the study observes a shift in O₃ formation sensitivity from VOC-sensitive to transitional or NO_X-sensitive regimes, signifying a notable transformation in the regional atmospheric chemistry conducive to O₃ generation. Aerosol feedback effects, through complex pathways including photolysis rate alterations and modifications in the vertical O₃ distribution, further compound the challenge of mitigating O₃ levels. Our research underscores the necessity for adaptive, region-specific strategies to mitigate O₃ pollution, providing potential insights for policymakers to formulate effective control measures.

自 2013 年以来，中国的 "清洁空气行动 "大大改善了环境 PM2.5 空气质量。然而，近年来城市地区的臭氧（O3）污染有所恶化，尤其是在东部地区。在这些高排放地区，O3 的形成非常复杂，受众多因素的制约。本研究利用天气研究和预报模式与化学耦合（WRF-Chem），通过对 2013 年和 2017 年的九个敏感性实验进行了综合分析，旨在厘清主要因素（如气象因素、人为排放、生物排放和气溶胶反馈机制）对观测到的 O3 浓度趋势的相对贡献。我们的研究结果表明，在经济活跃的苏南地区，臭氧日均最大值 8 小时平均值（MDA8）明显上升，而在欠发达的苏北地区，臭氧日均最大值 8 小时平均值（MDA8）则有所下降。研究发现，人为排放变化是臭氧变化的主要驱动因素，气象条件和气溶胶反馈效应也产生了重大影响，而生物排放变化的作用较小。在气象因素方面，我们发现与2013年相比，2017年气象热力因素（太阳辐射增强和气温升高）的变化对O3形成的影响比热力驱动的动力因素（边界层高度和风速）的变化更为明显。此外，研究观察到 O3 形成的敏感性从对挥发性有机化合物敏感转变为对过渡或氮氧化物敏感，这标志着有利于 O3 生成的区域大气化学发生了显著变化。气溶胶反馈效应通过复杂的途径，包括光解速率的改变和臭氧垂直分布的改变，进一步加剧了降低臭氧水平的挑战。我们的研究强调了采取适应性强、针对特定地区的战略来减轻臭氧污染的必要性，为决策者制定有效的控制措施提供了潜在的启示。

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引用次数: 0

Machine-learning downscaling of GPM satellite precipitation products in mountainous regions: A case study in Chongqing 山区 GPM 卫星降水产品的机器学习降尺度：重庆案例研究

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-20 DOI: 10.1016/j.atmosres.2024.107698

High-quality precipitation data are essential for research in hydrology, meteorology and ecology. Nevertheless, in mountainous regions with intricate terrain, the reliability of gridded precipitation data derived from station data interpolation is low due to the limited number of stations caused by the difficulty of station setup. Current satellite precipitation products suffer from low spatial resolution, making them unsuitable for hydrological and meteorological research at small and medium scales. Their application in mountainous regions with significant spatiotemporal heterogeneity is even more challenging. To this end, downscaling satellite precipitation products has become an effective method for obtaining accurate spatial distribution information of precipitation in these regions. This study employs a method of first calibration followed by downscaling analysis of GPM daily precipitation product in the Chongqing area using random forest (RF), extreme gradient boosting (XGBoost), and long short-term memory (LSTM) algorithms. Ultimately, the spatial resolution of GPM product is improved from 0.1° to 0.01° (∼1 km). The findings demonstrate that: (1) the station-calibrated GPM precipitation product performed better than the original GPM product, and it is closer to the station measurements; (2) in practical applications, the LSTM downscaling algorithm can effectively enhance spatial resolution without compromising accuracy, whereas RF and XGBoost incur considerable accuracy loss when enhancing spatial resolution; (3) the downscaled results from all three algorithms were consistent with the calibrated GPM precipitation maps and significantly improved the spatial details of precipitation. Among them, the results of the LSTM method exhibited greater continuity in the spatial distribution of precipitation, aligning more closely with the characteristics of precipitation distribution. In summary, the LSTM algorithm demonstrates greater potential for the downscaling of GPM precipitation product in the study area. This research provides a promising high-quality precipitation data generation scheme for mountainous regions with sparse station coverage and complex terrain and landforms.

高质量的降水数据对水文学、气象学和生态学研究至关重要。然而，在地形复杂的山区，由于站点设置困难导致站点数量有限，通过站点数据插值得出的网格降水数据可靠性较低。目前的卫星降水产品空间分辨率低，不适合中小尺度的水文和气象研究。在具有显著时空异质性的山区应用这些产品则更具挑战性。为此，降尺度卫星降水产品已成为获取这些地区降水精确空间分布信息的有效方法。本研究采用随机森林（RF）、极梯度提升（XGBoost）和长短期记忆（LSTM）算法，对重庆地区的 GPM 日降水量产品进行先校准后降尺度分析。最终，GPM 产品的空间分辨率从 0.1°提高到 0.01°（∼1 公里）。研究结果表明(1）台站校正后的 GPM 降水量产品比原始 GPM 产品性能更好，更接近台站实测数据；（2）在实际应用中，LSTM 降尺度算法可以在不影响精度的情况下有效提高空间分辨率，而 RF 和 XGBoost 在提高空间分辨率时会造成相当大的精度损失；（3）三种算法的降尺度结果与校正后的 GPM 降水图一致，显著改善了降水的空间细节。其中，LSTM 方法的结果在降水空间分布上表现出更强的连续性，更贴近降水分布特征。总之，LSTM 算法在研究区域的 GPM 降水量产品降尺度方面表现出更大的潜力。这项研究为站点覆盖稀少、地形地貌复杂的山区提供了一种有前景的高质量降水数据生成方案。

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引用次数: 0

Monitoring aerosol optical depth during the Arctic night: Instrument development and first results 北极夜间气溶胶光学深度监测：仪器开发和初步结果

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-18 DOI: 10.1016/j.atmosres.2024.107667

Moon-photometric measurements were made at two locations in the Arctic during winter nights using two different modified Sun photometers; a Carter Scott SP02 and a Precision Filter Radiometer (PFR) developed at PMOD/WRC. Values of aerosol optical depth (AOD) were derived from spectral irradiance measurements made at four wavelengths for each of the devices. The SP02 was located near Barrow, Alaska and recorded data from November 2012 to March 2013, spanning five lunar cycles, while the PFR was deployed to Ny-Ålesund, Svalbard each winter from February 2014 to February 2019 for a total of 56 measurement periods. A methodology was developed to process the raw data, involving calibration of the instruments and normalizing measured spectral irradiance values in accordance with site-specific determinations of the extraterrestrial atmospheric irradiance (ETI) as Moon phase cycled. Uncertainties of the derived AOD values were also evaluated and found to be in the range, 0.006–0.030, depending on wavelength and which device was evaluated.

The magnitudes of AOD determined for the two sites were in general agreement with those reported in the literature for sunlit periods just before and after the dark periods of Arctic night. Those for the PFR were also compared with data obtained using star photometers and a Cimel CE318-T, recently deployed to Ny-Ålesund, showing that Moon photometry is viable as a means to monitor AOD during the Arctic night. Such data are valuable for more complete assessments of the role aerosols play in modulating climate, the validation of AOD derived using various remote sensing techniques, and applications related to climate modeling.

利用卡特-斯科特 SP02 和 PMOD/WRC 开发的精密滤光辐射计（PFR）这两种不同的改进型太阳光度计，在北极的两个地点进行了冬夜月光测量。气溶胶光学深度（AOD）值是通过对每种设备的四个波长进行光谱辐照度测量得出的。SP02 位于阿拉斯加巴罗附近，记录了 2012 年 11 月至 2013 年 3 月期间的数据，跨越了五个月球周期；而 PFR 则于 2014 年 2 月至 2019 年 2 月期间的每个冬季部署在斯瓦尔巴特群岛的 Ny-Ålesund，共计 56 个测量周期。制定了一套处理原始数据的方法，包括校准仪器，并根据月相周期中特定地点确定的地外大气辐照度（ETI）对测得的光谱辐照度值进行归一化处理。还对得出的 AOD 值的不确定性进行了评估，发现其范围在 0.006-0.030 之间，具体取决于波长和评估的设备。此外，还将 PFR 的数据与使用星光光度计和最近部署在 Ny-Ålesund 的 Cimel CE318-T 获得的数据进行了比较，结果表明月球光度计是监测北极夜间 AOD 的可行方法。这些数据对于更全面地评估气溶胶在调节气候方面的作用、验证利用各种遥感技术得出的AOD以及与气候建模有关的应用都很有价值。

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引用次数: 0

Study on the characteristics of urban background ozone pollution based on long-term observations from mountain sites in China during 2015–2022 基于 2015-2022 年中国山区站点长期观测的城市背景臭氧污染特征研究

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research

Pub Date : 2024-09-18 DOI: 10.1016/j.atmosres.2024.107696

In recent years, Chinese cities have faced persistent O₃ pollution challenges. O₃ concentrations at urban mountain sites, serving as proxies for urban background O₃ levels, can help address data gaps in O₃ research in China. This study, for the first time, analyzed O₃ data from ten urban mountain sites during 2015–2022 using statistical methods like the Mann-Kendall test, Theil-Sen slope estimation, and Pearson correlation analysis to reveal characteristics and trends in urban background O₃ and proposed a metric for assessing mountain sites as urban background stations. Results indicate that O₃ at mountain sites were generally higher than at plain sites, regardless of mean, 10th percentile, or 90th percentile the average maximum daily 8-h average (MDA8) O₃. Although mountain sites exhibited similar annual and diurnal variations as plain sites, their amplitudes were significantly lower. Significant upward trends (P < 0.05) in MDA8 O₃ were observed mainly at plain sites, whereas trends at mountain sites were insignificant (P > 0.05) during 2015–2022. The increase in urban ground-level O₃ was largely due to changes in VOCs and NO_x emission structures, which reduce nighttime titration effects while enhancing daytime O₃ production. The insignificant trends observed at mountain sites suggest that these mountain sites may be in NO_x-limited or transitional regimes rather than VOCs-limited regimes, which is also associated with their lower NO_x concentrations compared to plain sites. These findings suggest that if China continues to prioritize the reduction of NO_x emissions, urban ground-level O₃ could further increase and approach the O₃ at mountain sites. Finally, this study proposes that the correlation in nighttime O₃ concentrations between mountain and plain stations can serve as a valuable indicator for evaluating the suitability of mountain stations as regional background stations in urban areas. It recommends mountain sites in cities such as Changji, Nanping for urban background O₃ monitoring stations.

近年来，中国城市面临持续的臭氧污染挑战。城市山区站点的臭氧浓度作为城市背景臭氧浓度的代用指标，有助于解决中国臭氧研究中的数据缺口问题。本研究首次采用Mann-Kendall检验、Theil-Sen斜率估计和Pearson相关分析等统计方法，分析了2015-2022年10个城市山地站点的O3数据，揭示了城市背景O3的特征和变化趋势，并提出了山地站点作为城市背景站点的评估指标。结果表明，无论臭氧浓度的平均值、日最大 8 小时平均值（MDA8）的第 10 百分位数还是第 90 百分位数，山区站点的臭氧浓度普遍高于平原站点。虽然山区观测点的年变化和日变化与平原观测点相似，但其振幅明显较低。在 2015-2022 年期间，主要在平原地区观察到 MDA8 O3 的显著上升趋势（P < 0.05），而山区地区的趋势不明显（P > 0.05）。城市地面臭氧浓度的增加主要是由于挥发性有机化合物和氮氧化物排放结构的变化，这减少了夜间的滴定效应，同时增加了白天的臭氧产生量。在山区站点观察到的不明显趋势表明，这些山区站点可能处于氮氧化物受限或过渡状态，而不是 VOCs 受限状态，这也与山区站点的氮氧化物浓度低于平原站点有关。这些研究结果表明，如果中国继续优先减少氮氧化物的排放，城市地面的臭氧浓度可能会进一步增加，并接近山区站点的臭氧浓度。最后，本研究提出，山区站点与平原站点夜间臭氧浓度的相关性可作为评估山区站点是否适合作为城市地区区域背景站点的重要指标。研究建议将昌吉、南平等城市的山区站点作为城市臭氧背景监测站。

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引用次数: 0