scholarly journals Impact of the Eurasian Teleconnection on the Interannual Variability of Haze-Fog in Northern China in January

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 113 ◽  
Author(s):  
Ye Li ◽  
Lifang Sheng ◽  
Chun Li ◽  
Yuhang Wang
Keyword(s):  
Interannual Variability ◽  
Geopotential Height ◽  
Circulation Pattern ◽  
Northern China ◽  
Cold Wave ◽  
Flux Analysis ◽  
Observation Data ◽  
Positive Anomaly ◽  
Eurasian Teleconnection ◽  
The Eu

Using meteorological observation data and NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data, the impacts of the atmospheric circulation pattern on the interannual variability of haze-fog in northern China in January are studied by means of statistical methods. The results showed that the Eurasian teleconnection (EU) at the 500 hPa isostatic surface is the most important pattern affecting the haze-fog frequency in northern China. However, the existing EU index cannot perfectly describe this pattern. To this end, this study selects three main activity centers to define a new EU index, which are located in the Europe (10 °E, 55 °N), Siberia (80 °E, 60 °N), and Shandong, China (120 °E, 40 °N). The difference between the existing EU index and the new EU index is mainly the position of the anomaly center of the 500 hPa geopotential height. The EU is in a negative phase in higher haze-fog years but is in a positive phase in lower haze-fog years. The 500 hPa geopotential height shows negative anomalies in Europe and East Asian and a positive anomaly in Siberia in the negative EU phase. Using Plumb wave activity flux analysis, it was found that the cold wave affecting northern China is less in the negative EU phase than that in the positive EU phase, which resulted in more haze-fog days. In addition, the results also showed that the EU pattern goes through a considerable development and decay within 13 days. The visibility starts to significantly decrease at a lag of −1 to 2 days in the negative EU peak phase and is influenced by the weak north wind that is caused by the high pressure.

Temporal and spatial variations of sandstorm and the related meteorological influences over northern China in the 21st century

2021 ◽  
Author(s):  
Jie Yang ◽  
Tianliang Zhao
Keyword(s):  
Land Surface ◽  
Source Region ◽  
Northern China ◽  
Northwest China ◽  
Gobi Desert ◽  
Taklimakan Desert ◽  
Observation Data ◽  
Average Wind Speed ◽  
Modis Ndvi ◽  
Temporal And Spatial

<p>In this study, we used the sandstorm data of 233 meteorological stations in northern China, conventional meteorological observation data and MODIS-NDVI data in the 40 years from 1980 to 2019 to analyze the spatio-temporal variation of sandstorms in northern China and its related meteorological effects in this century.</p><p>The results show that: 1) The average number of sandstorm days in northern China has been fluctuating and decreasing since the beginning of this century, and increasing from 2017 to 2019. Spring is the main season of dust storm, and the springtime proportion of sandstorm days decreases year by year. 2) In the 1980s and 1990s, sandstorms covered almost covered the whole northwest region; Since the beginning of this century, the range of sandstorm days in the whole Northwest China has shown an obvious decadal downward trend. The spatial pattern of sandstorm days in northern China has been shrinking and moving westward since 2000, and the dominant position of the Gobi Desert in the Asian dust source region has been decreasing year by year. The high sandstorm days were located in the Taklimakan Desert with the increasing trend of sandstorm days year by year. 3) The temporal and spatial variation of sandstorm days in northern China is closely related to the increase of vegetation cover with the greenness and wetness of the land surface, the decreases of average wind speed and gale days, and the significant increase of annual precipitation in northern China after 2000.</p>

scholarly journals Influence of the Bermuda High on interannual variability of summertime ozone in the Houston-­Galveston-Brazoria region

2016 ◽  
Author(s):  
Yuxuan Wang ◽  
Beixi Jia ◽  
Sing-Chun Wang ◽  
Mark Estes ◽  
Lu Shen ◽  
...  
Keyword(s):  
Wind Speed ◽  
Interannual Variability ◽  
Large Scale ◽  
Gulf Coast ◽  
Surface Ozone ◽  
Circulation Pattern ◽  
Local Scale ◽  
Metropolitan Region ◽  
Southern Us ◽  
Mlr Model

Abstract. The Bermuda High (BH) quasi-permanent pressure system is the key large-scale circulation pattern influencing summertime weather over the eastern and southern US. Here we developed a multiple linear regression (MLR) model to characterize the effect of the BH on year-to-year changes of monthly-mean maximum daily 8-hour average (MDA8) ozone in the Houston-Galveston-Brazoria (HGB) metropolitan region during June, July and August (JJA). The BH indicators include the longitude of the BH western edge (BH-Lon), and the BH intensity index (BHI) defined as the pressure gradient along its western edge. Both BH-Lon and BHI are selected by MLR as significant predictors (p < 0.05) of the interannual (1990–2015) variability of the HGB-mean ozone throughout JJA, while local-scale meridional wind speed is selected as an additional predictor for August only. Local-scale temperature and zonal wind speed are not identified as important factors for any summer month. The best-fit MLR model can explain 61 %–72 % of the interannual variability of the HGB-mean summertime ozone over 1990–2015 and shows good performance in cross-validation (R2 higher than 0.48). The BH-Lon is the most important factor, which alone explains 38 %–48 % of such variability. The location and strength of the Bermuda High appears to control whether or not low-ozone maritime air from the Gulf of Mexico can enter southeastern Texas and affect air quality. This mechanism also applies to other coastal urban regions along the Gulf Coast (e.g. New Orleans, LA; Mobile, AL; and Pensacola, FL), suggesting that the BH circulation pattern can affect surface ozone variability through a large portion of the Gulf Coast.

scholarly journals Variability in snow cover phenology in China from 1952 to 2010

2016 ◽  
Vol 20 (2) ◽  
pp. 755-770 ◽  
Author(s):  
Chang-Qing Ke ◽  
Xiu-Cang Li ◽  
Hongjie Xie ◽  
Dong-Hui Ma ◽  
Xun Liu ◽  
...  
Keyword(s):  
Snow Cover ◽  
Onset Date ◽  
Changbai Mountains ◽  
Observation Data ◽  
Positive Anomaly ◽  
The Loess Plateau ◽  
Climate Variable ◽  
Shandong Peninsula ◽  
North Xinjiang ◽  
Multiple Variables

Abstract. Daily snow observation data from 672 stations in China, particularly the 296 stations with over 10 mean snow cover days (SCDs) in a year during the period of 1952–2010, are used in this study. We first examine spatiotemporal variations and trends of SCDs, snow cover onset date (SCOD), and snow cover end date (SCED). We then investigate the relationships of SCDs with number of days with temperature below 0 °C (TBZD), mean air temperature (MAT), and Arctic Oscillation (AO) index. The results indicate that years with a positive anomaly of SCDs for the entire country include 1955, 1957, 1964, and 2010, and  years with a negative anomaly of SCDs include 1953, 1965, 1999, 2002, and 2009. The reduced TBZD and increased MAT are the main reasons for the overall late SCOD and early SCED since 1952. This explains why only 12 % of the stations show significant shortening of SCDs, while 75 % of the stations show no significant change in the SCDs trends. Our analyses indicate that the distribution pattern and trends of SCDs in China are very complex and are not controlled by any single climate variable examined (i.e. TBZD, MAT, or AO), but a combination of multiple variables. It is found that the AO has the maximum impact on the shortening trends of SCDs in the Shandong peninsula, Changbai Mountains, Xiaoxingganling, and north Xinjiang, while the combined TBZD and MAT have the maximum impact on the shortening trends of SCDs in the Loess Plateau, Tibetan Plateau, and Northeast Plain.

scholarly journals Nine-year spatial and temporal evolution of desert dust aerosols over South and East Asia as revealed by CALIOP

2018 ◽  
Vol 18 (2) ◽  
pp. 1337-1362 ◽  
Author(s):  
Emmanouil Proestakis ◽  
Vassilis Amiridis ◽  
Eleni Marinou ◽  
Aristeidis K. Georgoulias ◽  
Stavros Solomos ◽  
...  
Keyword(s):  
East Asia ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Indian Subcontinent ◽  
Northern China ◽  
Dust Aerosol ◽  
Observation Data ◽  
Transport Pathways ◽  
Desert Dust ◽  
Dust Aerosols

Abstract. We present a 3-D climatology of the desert dust distribution over South and East Asia derived using CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data. To distinguish desert dust from total aerosol load we apply a methodology developed in the framework of EARLINET (European Aerosol Research Lidar Network). The method involves the use of the particle linear depolarization ratio and updated lidar ratio values suitable for Asian dust, applied to multiyear CALIPSO observations (January 2007–December 2015). The resulting dust product provides information on the horizontal and vertical distribution of dust aerosols over South and East Asia along with the seasonal transition of dust transport pathways. Persistent high D_AOD (dust aerosol optical depth) values at 532 nm, of the order of 0.6, are present over the arid and semi-arid desert regions. Dust aerosol transport (range, height and intensity) is subject to high seasonality, with the highest values observed during spring for northern China (Taklimakan and Gobi deserts) and during summer over the Indian subcontinent (Thar Desert). Additionally, we decompose the CALIPSO AOD (aerosol optical depth) into dust and non-dust aerosol components to reveal the non-dust AOD over the highly industrialized and densely populated regions of South and East Asia, where the non-dust aerosols yield AOD values of the order of 0.5. Furthermore, the CALIPSO-based short-term AOD and D_AOD time series and trends between January 2007 and December 2015 are calculated over South and East Asia and over selected subregions. Positive trends are observed over northwest and east China and the Indian subcontinent, whereas over southeast China trends are mostly negative. The calculated AOD trends agree well with the trends derived from Aqua MODIS (Moderate Resolution Imaging Spectroradiometer), although significant differences are observed over specific regions.

scholarly journals Observation-derived ice growth curves show patterns and trends in maximum ice thickness and safe travel duration of Alaskan lakes and rivers

2020 ◽  
Author(s):  
Christopher D. Arp ◽  
Jessica E. Cherry ◽  
Dana R.N. Brown ◽  
Allen C. Bondurant ◽  
Karen L. Endres
Keyword(s):  
Interannual Variability ◽  
Growth Curves ◽  
Cold Season ◽  
Ice Thickness ◽  
Observation Data ◽  
Regional Variability ◽  
Winter Climate ◽  
Ice Growth ◽  
Freshwater Ice ◽  
Northern Regions

Abstract. The formation, growth, and decay of freshwater ice on lakes and rivers are fundamental processes of northern regions with wide ranging implications for socio-ecological systems. Ice thickness at the end of winter is perhaps the best integration of cold-season weather and climate, while the duration of thick and growing ice cover is a useful indicator for the winter travel and recreation season. Both maximum ice thickness (MIT) and ice travel duration (ITD) can be estimated from temperature-driven ice growth curves fit to ice thickness observations. We simulated and analyzed ice growth curves based on ice thickness data collected from a range of observation programs throughout Alaska spanning the past 20–60 years to understand patterns and trends in lake and river ice. Results suggest reductions in MIT (thinning) in several northern, interior, and coastal regions of Alaska and overall greater interannual variability in rivers compared to lakes. Interior regions generally showed less variability in MIT and even slightly increasing trends in at least one river site. Average ITD ranged from 214 days in the northern-most lakes to 114 days across southern-most lakes with significant decreases in duration for half of sites. River ITD showed low regional variability, but high interannual variability, underscoring the challenges with predicting seasonally-consistent river travel. Standardization and analysis of these ice observation data provide a comprehensive summary for understanding changes in winter climate and its impact on freshwater ice services.

scholarly journals Observed Quantile Features of Summertime Temperature Trends over China: Non-Negligible Role of Temperature Variability

2021 ◽  
Vol 9 ◽  
Author(s):  
Xing Li ◽  
Xiao Li ◽  
Hedi Ma ◽  
Wenjian Hua ◽  
Shanlei Sun ◽  
...  
Keyword(s):  
Yangtze River Basin ◽  
Northern China ◽  
Temperature Variability ◽  
Ecological Impacts ◽  
Observation Data ◽  
Temperature Trends ◽  
Quantile Regression Analysis ◽  
The Yangtze River Basin ◽  
Mean State

Changes in temperature variability can have more serious social and ecological impacts than changes in the mean state of temperature, especially when they are concurrent with global warming. The present study examines the summertime temperatures’ trends over China from the quantile perspective. Through fully investigating the quantile trends (QTs) of the maximum (Tmax) and minimum temperature (Tmin) using the homogenized observation data and quantile regression analysis, we identify evident region-specific quantile features of summertime temperature trends. In most of northern China, the QTs in Tmax and Tmin for all percentiles generally show strong uniform warmings, which are dominated by a warm shift in mean state temperatures. In contrast, the QTs of Tmax in the Yangtze River Basin show distinguishable inter-quantile features, i.e., an increasing tendency of QTs from cooling trends in the lower percentile to warming trends in the higher percentile. Further investigations show that such robust growing QTs of Tmax across quantiles are dominated by the temperature variance. Our results highlight that more attention should be paid to the region-specific dominance of temperature variability in trends and the related causes.

scholarly journals EU-Citizen.Science: A Platform for Mainstreaming Citizen Science and Open Science in Europe

2021 ◽  
Vol 3 (1) ◽  
pp. 136-149
Author(s):  
Katherin Wagenknecht ◽  
Tim Woods ◽  
Francisco García Sanz ◽  
Margaret Gold ◽  
Anne Bowser ◽  
...  
Keyword(s):  
Citizen Science ◽  
Data Model ◽  
Open Science ◽  
Observation Data ◽  
The Public ◽  
Metadata Model ◽  
Training Materials ◽  
Different Types ◽  
And Training ◽  
The Eu

Citizen Science (CS) is a prominent field of application for Open Science (OS), and the two have strong synergies, such as: advocating for the data and metadata generated through science to be made publicly available [ 1 ]; supporting more equitable collaboration between different types of scientists and citizens; and facilitating knowledge transfer to a wider range of audiences [ 2 ]. While primarily targeted at CS, the EU-Citizen. Science platform can also support OS. One of its key functions is to act as a knowledge hub to aggregate, disseminate and promote experience and know-how; for example, by profiling CS projects and collecting tools, resources and training materials relevant to both fields. To do this, the platform has developed an information architecture that incorporates the public participation in scientific research (PPSR)—Common Conceptual Model ① . This model consists of the Project Metadata Model, the Dataset Metadata Model and the Observation Data Model, which were specifically developed for CS initiatives. By implementing these, the platform will strengthen the interoperating arrangements that exist between other, similar platforms (e.g., BioCollect and SciStarter) to ensure that CS and OS continue to grow globally in terms of participants, impact and fields of application.

Study on the Influence of Heat Wave and Cold Wave Characteristics and Vulnerable Areas in Busan, Ulsan and Gyeongsangnam-do

2020 ◽  
Author(s):  
Miyeong Jo ◽  
Jiyeun Ye ◽  
Jihye Yun ◽  
Jaeeun You ◽  
Juyeong Kim ◽  
...  
Keyword(s):  
Heat Wave ◽  
Heat Waves ◽  
Weather Conditions ◽  
Cold Weather ◽  
Current Status ◽  
Maximum Temperature ◽  
Cold Wave ◽  
Observation Data ◽  
Physical Damage ◽  
Wave Impact

&lt;p&gt;The frequency of extreme weather phenomena such as heat wave and cold wave has increased recently, and the intensity of weather has been strengthened, resulting in human and physical damage. The Republic of Korea has been working to reduce damage since 2018 by including heat and cold waves in natural disasters. The Korea Meteorological Administration (KMA) also provides impact-based forecasts, which requires research that suits local characteristics. In this study, weather observation data related to the summer heat wave in Busan, Ulsan and South Gyeongsang Province was analyzed to determine the weather conditions for the heat wave. In addition, in relation to the heat wave impact-based forecast that was provided regularly in 2019, the heat threshold was applied by comparing the current status of the heat-related patients with the maximum temperature, the number of consecutive days of the heat wave and the current status of the heat-related patients. The impacts of heat waves in different fields were analyzed, including livestock waste, fisheries food damage, and heat damage by crops. The cold wave also analyzed the number of days of cold wave in Busan, Ulsan, and South Gyeongsang Province by comparing the lowest temperature with the current status of cold-related patients. The impacts of cold weather conditions such as wind direction, wind speed and the number of consecutive days of the cold wave were also analyzed. Further, for regular provision of cold wave impact-based forecast to be implemented in 2020, the impacts of each cold wave vulnerable areas suitable for Busan, Ulsan, and South Gyeongsang Province were analyzed and referred to when applying cold wave thresholds.&lt;/p&gt;

scholarly journals HESFIRE: a global fire model to explore the role of anthropogenic and weather drivers

2015 ◽  
Vol 12 (3) ◽  
pp. 887-903 ◽  
Author(s):  
Y. Le Page ◽  
D. Morton ◽  
B. Bond-Lamberty ◽  
J. M. C. Pereira ◽  
G. Hurtt
Keyword(s):  
Interannual Variability ◽  
Anthropogenic Activities ◽  
Optimization Procedure ◽  
Realistic Model ◽  
Ecosystem Dynamics ◽  
Burned Area ◽  
Model Parameters ◽  
Observation Data ◽  
Fire Model ◽  
Fire Activity

Abstract. Vegetation fires are a major driver of ecosystem dynamics and greenhouse gas emissions. Anticipating potential changes in fire activity and their impacts relies first on a realistic model of fire activity (e.g., fire incidence and interannual variability) and second on a model accounting for fire impacts (e.g., mortality and emissions). In this paper, we focus on our understanding of fire activity and describe a new fire model, HESFIRE (Human–Earth System FIRE), which integrates the influence of weather, vegetation characteristics, and human activities on fires in a stand-alone framework. It was developed with a particular emphasis on allowing fires to spread over consecutive days given their major contribution to burned areas in many ecosystems. A subset of the model parameters was calibrated through an optimization procedure using observation data to enhance our knowledge of regional drivers of fire activity and improve the performance of the model on a global scale. Modeled fire activity showed reasonable agreement with observations of burned area, fire seasonality, and interannual variability in many regions, including for spatial and temporal domains not included in the optimization procedure. Significant discrepancies are investigated, most notably regarding fires in boreal regions and in xeric ecosystems and also fire size distribution. The sensitivity of fire activity to model parameters is analyzed to explore the dominance of specific drivers across regions and ecosystems. The characteristics of HESFIRE and the outcome of its evaluation provide insights into the influence of anthropogenic activities and weather, and their interactions, on fire activity.

scholarly journals Dynamic Diagnosis of Stratospheric Sudden Warming Event in the Boreal Winter of 2018 and Its Possible Impact on Weather over North America

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 438
Author(s):  
Jincai Xie ◽  
Jinggao Hu ◽  
Haiming Xu ◽  
Shuai Liu ◽  
Huan He
Keyword(s):  
North America ◽  
Circulation Pattern ◽  
Onset Date ◽  
Cold Wave ◽  
Boreal Winter ◽  
Stratospheric Polar Vortex ◽  
Stratospheric Sudden Warming ◽  
Northeastern North America ◽  
Northwestern North America ◽  
Dynamic Diagnosis

In the winter of 2018, a major stratospheric sudden warming (SSW) event occurred in the Northern Hemisphere. This study performs a dynamic diagnosis on this 2018 SSW event and analyzes its possible impact on the weather over North America. The result shows that the ridge over Alaska in the mid-troposphere and the trough over the northeastern North America are the prominent tropospheric precursory signals before the occurrence of this SSW event. The signals appear 10 days before the SSW, which greatly enhances the propagation of the planetary wavenumber 2 from the troposphere to the extratropical stratosphere. The collapse process of stratospheric polar vortex indicates that this SSW is a typical vortex splitting event dominated by planetary wavenumber 2. Additionally, after the SSW onset, no reflection of the stratosphere on the tropospheric planetary waves is observed. Thus, this event can also be classified as an absorbing-type SSW event. A noticeable cold wave occurs in the northwestern North America within 10 days after the 2018 SSW. This cold wave is probably associated with the SSW-related west–east dipole, namely a ridge over Alaska and a trough over the northeastern North America in the mid-troposphere that lasted up to 10 days after the onset date. The composite analysis of the other seven SSW events with an emergence of similar mid-tropospheric circulation pattern after SSW onset date yields coincident 2-meter temperature anomalies in the northwestern North America, which confirms the above conclusion to some extent.

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