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He Q.S.,Shanghai Meteorological Service | Li C.C.,Peking University | Ma J.Z.,Chinese Academy of Meteorological Sciences | Wang H.Q.,Donghua University | And 5 more authors.
Journal of the Atmospheric Sciences | Year: 2013

As part of the Tibet Ozone, Aerosol and Radiation (TOAR) project, a micropulse lidar was operated in Naqu (31.5°N, 92.1°E; 450° m MSL) on the Tibetan Plateau to observe cirrus clouds continuously from 19 July to 26 August 2011. During the experiment, the time coverage of ice clouds only was 15% in the upper troposphere (above 9.5 km MSL). The cirrus top/bottom altitudes (mean values of 15.6/14.7 km) are comparable to those measured previously at tropical sites but relatively higher than those measured at midlatitude sites. The majority of the cloud layers yielded a lidar ratio between 10 and 40 sr, with a mean value of 28 6 15 sr, characterized by a bimodal frequency distribution. Subvisible, thin, and opaque cirrus formation was observed in 16%, 34%, and 50% of all cirrus cases, respectively. A mean cirrus optical depth of 0.33 was observed over the Tibetan Plateau, slightly higher than those in the subtropics and tropics. With decreasing temperature, the lidar ratio increased slightly, whereas the mean extinction coefficient decreased significantly. The occurrence of clouds is highly correlated with the outgoing longwave radiation and the strong cold perturbations in the upper troposphere. Deep convective activity and Rossby waves are important dynamical processes that control cirrus variations over the Tibetan Plateau, where both anvil cirrus outflowing from convective cumulonimbus clouds and large-scale strong cold perturbations in the upper troposphere should play an important role in cirrus formation. © 2013 American Meteorological Society.

He Q.S.,Shanghai Meteorological Service | Li C.C.,Peking University | Ma J.Z.,Chinese Academy of Meteorological Sciences | Wang H.Q.,Donghua University | And 4 more authors.
Atmospheric Chemistry and Physics | Year: 2014

Vertical profiles of aerosol extinction coefficients were measured by a micro-pulse lidar at Naqu (31.5° N, 92.1° E; 4508 m a.m.s.l.), a meteorological station located on the central part of the Tibetan Plateau during summer 2011. Observations show a persistent maximum in aerosol extinction coefficients in the upper troposphere-lower stratosphere (UTLS). These aerosol layers were generally located at an altitude of 18-19 km a.m.s.l., 1-2 km higher than the tropopause, with broad layer depth ranging approximately 3-4 km and scattering ratio of 4-9. Daily averaged aerosol optical depths (AODs) of the enhanced aerosol layers in UTLS over the Tibetan Plateau varied from 0.007 to 0.030, in agreement with globally averaged levels of 0.018 ± 0.009 at 532 nm from previous observations, but the percentage contributions of the enhanced aerosol layers to the total AOD over the Tibetan Plateau are higher than those observed elsewhere. The aerosol layers in UTLS wore off gradually with the reducing intensity of the Asian monsoon over the Tibetan Plateau at the end of August. The eruption of Nabro volcano on 13 June 2011 is considered an important factor to explain the enhancement of tropopause aerosols observed this summer over the Tibetan Plateau.

He Q.,Shanghai Meteorological Service | He Q.,Shanghai Key Laboratory of Meteorology and Health | Li C.,Peking University | Geng F.,Shanghai Meteorological Service | And 6 more authors.
Remote Sensing of Environment | Year: 2016

In this study, a vertical correction method based on a two-layer aerosol model is proposed to estimate the surface-level visibility from satellite measurements of aerosol optical depth (AOD). The meteorological parameters from the re-analysis data of the National Centers for Environmental Prediction (NCEP) are applied to estimate the aerosol layer height (ALH) of the two-layer aerosol model via an automatic workflow. The estimated extinction coefficients near the surface by AOD/ALH over the single point of a lidar site in Shanghai agree well with those of the ground measurements from a visibility sensor, with a correlation coefficient of 0.86 and root mean squared error (RMS) of 0.19 km-1 for the data set from April 18, 2008 to April 30, 2014. The season-long spatial comparison demonstrates that most of the correlation coefficients (90%) are >0.6, and more than half of the samples (68%) have coefficients higher than 0.7 for the data set from January 1 to April 30, 2014. Dust transportation and higher relative humidity (RH) have been confirmed to be important factors in reducing the accuracy of estimated visibility, as these situations fail to meet the assumptions of the two-layer model. Additionally, the less-rigorous cloud mask algorithm of the Moderate Resolution Imaging Spectroradiometer (MODIS)/AOD might lead to overestimates of AOD, and further underestimating of the surface-level visibility. The spatial variation of temporal correlation coefficients shows that most comparison sites (>74%) of satellite estimations agree well with the surface-level visibility measurements, with correlation coefficients up to 0.6 during the study period. The northern area of Eastern China presented better agreement than the southern area. This may be related to the complex underlying surface characteristics and higher RH in the southern part. This work will significantly improve the quality of climate simulations and air quality forecasts in Eastern China. © 2016 Elsevier Inc.

He Q.,Shanghai Meteorological Service | Zhao X.,Nanjing University of Information Science and Technology | Lu J.,Nanjing University of Information Science and Technology | Lu J.,Oklahoma State University | And 6 more authors.
Particuology | Year: 2015

Anthropogenic aerosols have significant impacts on the environment and human health in the Yangtze River Delta region, one of the most densely populated regions in the world. A biomass-burning plume swept across this area (Shanghai) in May 2009, leading to changes in the physical and optical properties of aerosols, which were investigated using ground-based remote sensing and in situ measurements via comparisons with dust pollution and background conditions. Experiments show that the biomass-burning plume led to an increase in the average aerosol optical depth (AOD) at 500 nm from 0.73 to 1.00 (37% higher), an absorption Angstrom exponent (AAE) of 1.48, and an increase in the Angstrom exponent (α) up to 1.53. Furthermore, local dust aerosols derived from road dust and/or construction dust also led to higher values of AOD (2.68) and AAE (2.16), and a daily average value of α of 1.05. For the biomass-burning plume, the aerosol particles exhibited significant variations in short-wavelength spectra. The single scattering albedo at 670 nm decreased remarkably under the influence of the biomass-burning plume, indicating the significant absorptive ability of the biomass-burning pollution and higher ratio of absorption aerosols within the plume. Under the effects of the biomass-burning, the volume concentration of fine-mode aerosols increased significantly and the PM-fine/PM-coarse volume concentration ratio reached 12.33. This relatively large change in fine-mode particles indicates that biomass-burning has a greater impact on fine-mode aerosols than on coarse-mode aerosols. © 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy ofSciences. Published by Elsevier B.V. All rights reserved.

Zhang Q.,Institute of Arid Meteorology | Zhang Q.,Lanzhou University | Wang S.,Institute of Arid Meteorology | Wang S.,Lanzhou University | And 2 more authors.
Science China Earth Sciences | Year: 2016

The adsorption of water vapor by soil is one of the crucial contributors to non-rainfall water on land surface, particularly over semi-arid regions where its contribution can be equivalent to precipitation and can have a major impact on dry agriculture and the ecological environment in these regions. However, due to difficulties in the observation of the adsorption of water vapor, research in this area is limited. This study focused on establishing a method for estimating the quantitative observation of soil water vapor adsorption (WVA), and exploring the effects of meteorological elements (e.g., wind, temperature, and humidity) and soil environmental elements (e.g., soil temperature, soil moisture, and the available energy of soil) on WVA by soil over the semi-arid region, Dingxi, by combining use of the L-G large-scale weighing lysimeter and meteorological observation. In addition, this study also analyzed the diurnal and annual variations of WVA amount, frequency, and intensity by soil, how they changed with weather conditions, and the contribution of WVA by soil to the land surface water budget. Results showed that WVA by soil was co-affected by various meteorological and soil environmental elements, which were more likely to occur under conditions of relative humidity of 6−50% and the diurnal variation of relative humidity was large, inversion humidity, wind velocity of 3−4 m/s, lower soil water content, low surface temperature and slightly unstable atmospheric conditions. There was a negative feedback loop between soil moisture and the adsorption of water vapor, and, moreover, the diurnal and annual variations of WVA amount and frequency were evident—WVA by soil mainly occurred in the afternoon, and the annual peak appeared in December and the valley in June, with obvious regional characteristics. Furthermore, the contribution of WVA by soil to the land surface water budget obviously exceeded that of precipitation in the dry season. © 2016 Science China Press and Springer-Verlag Berlin Heidelberg

Wu J.-B.,Shanghai Meteorological Service | Xu J.,Shanghai Meteorological Service | Pagowski M.,National Oceanic and Atmospheric Administration | Geng F.,Shanghai Meteorological Service | And 4 more authors.
Particuology | Year: 2015

This study focuses on the importance of initial conditions to air-quality predictions. We ran assimilation experiments using the WRF-Chem model and grid-point statistical interpolation (GSI), for a 9-day severe particulate matter pollution event that occurred in Shanghai in December 2013. In this application, GSI used a three-dimensional variational approach to assimilate ground-based PM2.5 observations into the chemical model, to obtain initial fields for the aerosol species. In our results, data assimilation significantly reduced the errors when compared to a simulation without assimilation, and improved forecasts of PM2.5 concentrations. Despite a drop in skill directly after the assimilation, a positive effect was present in forecasts for at least 12-24 h, and there was a slight improvement in the 48-h forecasts. In addition to performing well in Shanghai, the verification statistics for this assimilation experiment are encouraging for most of the surface stations in China. © 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy ofSciences. Published by Elsevier B.V. All rights reserved.

He Q.,Shanghai Meteorological Service | He Q.,Shanghai Key Laboratory of Meteorology and Health | Zhou G.,Shanghai Meteorological Service | Zhou G.,Shanghai Key Laboratory of Meteorology and Health | And 3 more authors.
Atmospheric Research | Year: 2016

The hygroscopic properties of aerosol particles have strong impact on climate as well as visibility in polluted areas. Understanding of the scattering enhancement due to water uptake is of great importance in linking dry aerosol measurements with relevant ambient measurements, especially for satellite retrievals. In this study, an observation-based algorithm combining meteorological data with the particulate matter (PM) measurement was introduced to estimate spatial distribution of indicators describing the integrated humidity effect in East China and the main factors impacting the hygroscopicity were explored. Investigation of 1year data indicates that the larger mass extinction efficiency αext values (>9.0m2/g) located in middle and northern Jiangsu Province, which might be caused by particulate organic material (POM) and sulfate aerosol from industries and human activities. The high level of POM in Jiangsu Province might also be responsible for the lower growth coefficient γ value in this region. For the inland junction provinces of Jiangsu and Anhui, a considerable higher hygroscopic growth region in East China might be attributed to more hygroscopic particles mainly comprised of inorganic salts (e.g., sulfates and nitrates) from several large-scale industrial districts distributed in this region. Validation shows good agreement of calculated PM2.5 mass concentrations with in situ measurements in most stations with correlative coefficients of over 0.85, even if several defective stations induced by station location or seasonal variation of aerosol properties in this region. This algorithm can be used for more accurate surface level PM2.5 retrieval from satellite-based aerosol optical depth (AOD) with combination of the vertical correction for aerosol profile. © 2015 Elsevier B.V..

Wang H.,Donghua University | Kang Y.,Donghua University | He Q.,Shanghai Meteorological Service | He Q.,Shanghai Key Laboratory of Meteorology and Health | Chen Y.,Donghua University
Particuology | Year: 2015

Black carbon (BC) aerosol mass carried by winds of varying directions from non-local sources was estimated based on hourly measured data of BC mass concentration (CBC) and meteorological parameters from January 2008 to December 2012 in Shanghai, and the relationship between annual average CBC and wind speed was analyzed. The results show that the annual average CBC decreased with wind speed for speeds exceeding 0.3 m/s. The relationship between the two was determined by a linear fit with correlation coefficient 0.88. Assuming BC aerosol mass of non-local sources transported by a southeast wind was zero, annual average BC concentrations (μg/m3) carried by winds of variable direction were 1.99 (southwest), 1.95 (west), 1.15 (northwest), 0.54 (south), 0.39 (north), 0.01 (northeast), and 0.01 (east). BC aerosol mass of non-local sources transported by wind to Shanghai was about 6404.05 t per year, among which the total contribution of southwest, west, and northwest winds was nearly 84%. The aerosol mass transported to Shanghai in winter accounted for 35% that of the entire year, and was greater than that of the other seasons. © 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy ofSciences. Published by Elsevier B.V. All rights reserved.

Chang L.-Y.,Shanghai Meteorological Service | Chang L.-Y.,Yangtze River Delta Center for Prediction and Warning of Environmental Meteorology | Xu J.-M.,Shanghai Meteorological Service | Xu J.-M.,Yangtze River Delta Center for Prediction and Warning of Environmental Meteorology | And 9 more authors.
Huanjing Kexue/Environmental Science | Year: 2016

To analyze the characteristics and formation mechanism of a heavy air pollution episode in Shanghai City from January 23th to January 24th, 2013, the observed data of PM2.5 concentration and ground meteorological data and the WRF-Chem model were collected. The analysis revealed that the synoptic necessary mechanism of the heavy air pollution episode could be characterized by the following patterns: Accompanied with weak cold front activities, the city experienced weak winds (i.e. stable atmosphere) at first and then northerly winds (i.e. pollutant transport process), causing the continuous increase and maintaining of pollutant concentration. The detailed results are shown as follows: Firstly, the stable atmosphere circulation pattern which lasted for 10 hours was not good for air pollution dispersion, as a result, local PM2.5 concentrations continued to increase and reached severe pollution level and the high concentrations maintained for 7 hours caused by the stable boundary layer (e.g. static surface winds and low level temperature inversion) during nighttime, and the average PM2.5 concentrations during the stable weather process was 172.4 μg·m-3. Secondly, the dispersion condition was slightly improved later on with the arrival of a weak cold front, the upstream pollution transportation occurred at the same time, leading to further increase of PM2.5 concentration (up to 280 μg·m-3), and the average PM2.5 concentration during the upstream transportation process was 213.6 μg·m-3. Numerical simulation with the WRF-Chem model showed that, average contribution of upstream transportation to local PM2.5 concentrations during the episode was 23%. Among them, the contribution during the stable weather and upstream transportation stage was 17.2% and 32.2%. Our results suggested that there were significant differences in the contribution of upstream transportation to the local PM2.5 concentration of Shanghai due to variation of weather conditions. Therefore, the government can design effective emission control strategy in advance taking pollution weather forecasting into account. © 2016, Science Press. All right reserved.

PubMed | CAS Institute of Earth Environment and Shanghai Meteorological Service
Type: | Journal: Scientific reports | Year: 2016

During the winter of 2015, there was a strong El Nino (ENSO) event, resulting in significant anomalies for meteorological conditions in China. Analysis shows that the meteorological conditions in December 2015 (compared to December 2014) had several important anomalies, including the following: (1) the surface southeasterly winds were significantly enhanced in the North China Plain (NCP); (2) the precipitation was increased in the south of eastern China; and (3) the wind speeds were decreased in the middle-north of eastern China, while slightly increased in the south of eastern China. These meteorological anomalies produced important impacts on the aerosol pollution in eastern China. In the NCP region, the PM

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