Anhui Institute of Meteorological science

Hefei, China

Anhui Institute of Meteorological science

Hefei, China
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Yang Y.,Hefei University of Technology | Yang Y.,Anhui Institute of Meteorological science | Fu Y.,Hefei University of Technology | Fu Y.,Anhui Institute of Meteorological science | And 2 more authors.
Atmospheric Science Letters | Year: 2017

The presences of anvil clouds significantly affect the tropical mean radiation budget and increase the uncertainty of climate model simulations. In this study, the climatological mean distributions of thick anvil parameters, such as top, bottom, occurrence, cloud effective radius (CER) and cloud optical depth (COD) in the tropics (20°S–20°N) are investigated by Tropical Rainfall Measuring Mission's (TRMM) precipitation radar (PR) and visible and infrared scanner (VIRS) from 1998 to 2007. The thick anvil radiative forcing at shortwave (0.2 ∼ 4 µm) and longwave (4 ∼ 50 µm) length, i.e. Shortwave radiative forcing (SRF) and Longwave radiative forcing (LRF) and their net effects at different altitudes are simulated with Santa Barbara DISORT Atmospheric Radiative Transfer Model (SBDART). The results show that thick anvils present higher top/bottom, smaller CER, and thicker COD over land than those over ocean. At the top of atmosphere (TOA), net radiative effects of thick anvils are positive warming, which means the earth-atmosphere system obtains energy forced by thick anvils. At earth surface, net radiative effects of thick anvils are positive warming at land surface and negative cooling at ocean surface, respectively. In general, anvil SRF, LRF and net effects vary with different geographical locations and also present large land–ocean differences in the tropics, due to different anvil properties forced by the surface heating and topography. All spatial patterns of stronger anvil SRF, LRF and net effects are well matched with the places where exist higher fractions of anvils, such as Asian monsoon zone, the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), tropical Africa, Mid-America and South America. In addition, the present work provides an evidence that it is an effective approach to calculate quantitatively the grid-cell SRF and LRF of cloud at a large scale by using the SBDART model with inputs from satellite observations. © 2017 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.

Sun L.,Anhui University of Science and Technology | Sun L.,CAS Institute of Atmospheric Physics | Yang Y.-J.,Anhui Institute of Meteorological science | Xian T.,Anhui University of Science and Technology | And 2 more authors.
Marine Ecology Progress Series | Year: 2010

Recent studies demonstrate that chlorophyll a (chl a) concentrations in ocean surface waters can be significantly enhanced due to typhoons. The present study investigated chl a concentrations in the middle of the South China Sea (SCS) from 1997 to 2007. Only the Category 1 (minimal) Typhoon Hagibis (2007) had a notable effect on chl a concentrations. Typhoon Hagibis had a strong upwelling potential due to its location near the equator, and the forcing time of the typhoon (>82 h) was much longer than the geostrophic adjustment time (∼63 h). The higher upwelling velocity and the longer forcing time increased the depth of the mixed-layer, which consequently induced a strong phytoplankton bloom that accounted for about 30% of the total annual chl a concentration in the middle of the SCS. Induction of significant upper ocean responses can be expected if the forcing time of a typhoon is long enough to establish strong upwelling. © Inter-Research 2010.

Yang Y.-J.,Anhui University of Science and Technology | Yang Y.-J.,Anhui Institute of Meteorological science | Sun L.,Anhui University of Science and Technology | Sun L.,State Oceanic Administration | And 3 more authors.
International Journal of Remote Sensing | Year: 2010

The responses of the upper ocean to typhoons were investigated by the observations of sea surface wind (SSW), sea surface temperature (SST), sea surface height anomaly (SSHA), chlorophyll-a (Chl-a) and Argo floats.TyphoonNamtheun had notable impacts on the upper ocean along its track from July to August 2004. The local processes (entrainment and upwelling) dominated the upper ocean responses in the regions of the pre-existing cold eddy and beneath the typhoon track, where the observed locations of upwelling, SSHA changes, SST cooling, and Chl-a enhancement were consistent with each other. Besides, there were cold tongues extending from the cold centres. The trajectories of Argo floats, along with the cold tongues, indicated that the surface advections induced such non-local responses.On the other hand, the following weak typhoon Malou had few impacts on the upper ocean. Finally, the mechanisms of the Chl-a concentration enhancement were sketched as the effects of both the local upwelling and the non-local advection. This study implies that some non-local processes, e.g. horizontal advections,may play a notable role in the upper ocean responses to the typhoons. © 2010 Taylor & Francis.

Sun L.,Anhui University of Science and Technology | Sun L.,State Oceanic Administration | Yang Y.-J.,Anhui University of Science and Technology | Yang Y.-J.,CAS Institute of Atmospheric Physics | And 4 more authors.
Atmosphere - Ocean | Year: 2012

Argo salinity and temperature profiles, along with other sea surface measurements, were used to explore the impacts of Typhoon Namtheun (2004) on the ocean. Namtheun took local enthalpy heat from the sea (0.39-0.7 × 10 8 J m-2), cooled the sea surface water as a result of vertical mixing (maximum 3-4°C) and produced heavy precipitation over the sea (100-180 mm). During this time, the vast latent heat released (2.6-4.4 × 108 J m-2) by the precipitation made a larger contribution to the typhoon's energy budget than the local air-sea enthalpy flux. In the upper ocean, the oceanic responses can be separated into two sub-processes, the fast spin-up accompanied by one-dimensional vertical mixing and the slow spin-down accompanied by the convergence of surface water. From Argo profiles on 28 July, it can be seen that the typhoon-induced surface mixing broke down the seasonal thermocline (approximately 20 db) within one day. In addition, the shallower (<200 db) convergence of the sea surface fresh water as a result of precipitation also made the post-typhoon water fresher (0.04 (practical salinity scale used)). In the deep ocean, the rapid upwelling at the top of the permanent thermocline suggests that the fast spin-up is a barotropic mechanism, probably gravity pressure. During the slow spin-down stage, the upwelling signal propagated downward (approximately 2 m h-1) from the shallow water to the deep ocean for about 10 days; this was a baroclinic process. The baroclinic mechanism was more effective in maintaining a cyclonic eddy than in maintaining an inertial wave, and the low sea surface height anomaly and upwelling lasted much longer than the inertial oscillation (>20 days as opposed to approximately 10 days). This change in vertical structure and long-term upwelling could have impacts on the ocean environment and even on the short-term climate.

Yang J.,Nanjing University of Information Science and Technology | Yang J.,Key Laboratory for Cloud Physics and Weather Modification | Xie Y.-J.,Nanjing University of Information Science and Technology | Shi C.-E.,Anhui Institute of Meteorological science | And 3 more authors.
Pure and Applied Geophysics | Year: 2012

Intensive field experiments focused on fog chemistry were carried out in the northern suburb of Nanjing during the winters of 2006 and 2007. Thirty-seven fog water samples were collected in nine fog events. Based on the chemical analysis results of those samples and the simultaneous measurements of air pollution gases and atmospheric aerosols, the chemical characteristics of fog water and their relations with air pollutants during fog evolution were investigated. The results revealed an average total inorganic ionic concentration TIC = 21.18 meq/L, and the top three ion concentrations were those of SO 4 2-, NH 4 + and Ca 2+ (average concentrations 6.99, 5.95, 3.77 meq/L, respectively). However, the average pH value of fog water was 5.85, which is attributable to neutralization by basic ions (NH 4 + and Ca 2+). The average TIC value of fog water measured in advection-radiation fog was around 2.2 times that in radiation fog, and the most abundant cation was NH 4 + in advection-radiation fog and Ca 2+ in radiation fog. In dense fog episodes, the concentration variations of primary inorganic pollution gases showed a "V"-shaped pattern, while those of volatile organic compounds (VOCs) displayed a "K"-shaped pattern. The dense fog acted as both the source and sink of atmospheric aerosol particles; fog processes enhanced particle formation, leading to the phenomenon that the aerosol concentration after fog dissipation was higher than that before the fog, and at the same time, mass concentration of PM 10 reached the lowest value in the late stage of extremely dense fog episodes because of the progressive accumulated effect of wet deposition of large fog droplets. Both air pollution gases and aerosols loading controlled the ion compositions of fog water. The Ca 2+ in fog water originated from airborne particles, while SO 4 2- and NH 4 + were from both heterogeneous production and soluble particulate species. © 2011 Springer Basel AG.

Yang J.,Nanjing University of Information Science and Technology | Yang J.,Key Laboratory for Cloud Physics and Weather Modification of China Meteorological Administration | Niu Z.-Q.,Nanjing University of Information Science and Technology | Shi C.-E.,Anhui Institute of Meteorological science | And 2 more authors.
Huanjing Kexue/Environmental Science | Year: 2010

Intensive field observations of fog/haze events, including simultaneous measurements of aerosol particle and fog droplet size distributions, were conducted in Nanjing in November, 2007. Four weather conditions (fog, mist, wet haze and haze) were distinguished based on visibility and liquid water content firstly. Then, the microphysical characteristics of coarse and fine particles in each condition were investigated. The results showed the dominant sequence of the four weather conditions was haze ↔ mist → wet haze → fog → wet haze → mist ↔ haze. The lasting time of pre-fog wet haze was longer than that of post-fog wet haze. The number, surface area and volume concentration of coarse particles with diameter larger than 2.0 micron in fog were much higher than those in the other three conditions, and the smallest concentrations were observed in haze. The size distributions of surface area and volume concentration exhibited multi-peak in fog droplets, while it showed single peak for coarse particles in haze, mist and wet haze. For the fine particles with diameter larger than 0.010 μm, the spectral shapes of surface area concentration are similar in fog (mist) and wet haze (haze) condition. The dominant size ranges of fine particle number concentration were in 0.04-0.13 μm and 0.02-0.14 μm for fog and wet haze, separately. The same dominant size ranges located in 0.02-0.06 μm for both mist and haze. During the transition processes from haze, mist and wet haze to fog, the concentration of smaller particles (less than 0.060-0.090 μm) reduced and vice versa for the corresponding larger particles. Temporal variation of aerosol number concentration correlated well with the root mean diameters negatively during the observation period. The number concentration of aerosol was the lowest and the mean diameter was the largest in fog periods.

Shi C.,Arizona State University | Shi C.,Anhui Institute of Meteorological science | Fernando H.J.S.,Arizona State University | Fernando H.J.S.,University of Notre Dame | Hyde P.,Arizona State University
Science of the Total Environment | Year: 2012

Phoenix, Arizona, has been an ozone nonattainment area for the past several years and it remains so. Mitigation strategies call for improved modeling methodologies as well as understanding of ozone formation and destruction mechanisms during seasons of high ozone events. To this end, the efficacy of lateral boundary conditions (LBCs) based on satellite measurements (adjusted-LBCs) was investigated, vis-à-vis the default-LBCs, for improving the predictions of Models-3/CMAQ photochemical air quality modeling system. The model evaluations were conducted using hourly ground-level ozone and NO 2 concentrations as well as tropospheric NO 2 columns and ozone concentrations in the middle to upper troposphere, with the 'design' periods being June and July of 2006. Both included high ozone episodes, but the June (pre-monsoon) period was characterized by local thermal circulation whereas the July (monsoon) period by synoptic influence. Overall, improved simulations were noted for adjusted-LBC runs for ozone concentrations both at the ground-level and in the middle to upper troposphere, based on EPA-recommended model performance metrics. The probability of detection (POD) of ozone exceedances (>75ppb, 8-h averages) for the entire domain increased from 20.8% for the default-LBC run to 33.7% for the adjusted-LBC run. A process analysis of modeling results revealed that ozone within PBL during bulk of the pre-monsoon season is contributed by local photochemistry and vertical advection, while the contributions of horizontal and vertical advections are comparable in the monsoon season. The process analysis with adjusted-LBC runs confirms the contributions of vertical advection to episodic high ozone days, and hence elucidates the importance of improving predictability of upper levels with improved LBCs. © 2011 Elsevier B.V.

Bi Y.,Hefei University of Technology | Chen Y.,Hefei University of Technology | Zhou R.,Hefei University of Technology | Yi M.,Hefei University of Technology | Deng S.,Anhui Institute of Meteorological science
Advances in Atmospheric Sciences | Year: 2011

To analyze the mechanism by which water vapor increase leads to cooling in the stratosphere, the effects of water-vapor increases on temperature in the stratosphere were simulated using the two-dimensional, interactive chemical dynamical radiative model (SOCRATES) of NCAR. The results indicate that increases in stratospheric water vapor lead to stratospheric cooling, with the extent of cooling increasing with height, and that cooling in the middle stratosphere is stronger in Arctic regions. Analysis of the radiation process showed that infrared radiative cooling by water vapor is a pivotal factor in middle-lower stratospheric cooling. However, in the upper stratosphere (above 45 km), infrared radiation is not a factor in cooling; there, cooling is caused by the decreased solar radiative heating rate resulting from ozone decrease due to increased stratospheric water vapor. Dynamical cooling is important in the middle-upper stratosphere, and dynamical feedback to temperature change is more distinct in the Northern Hemisphere middle-high latitudes than in other regions and significantly affects temperature and ozone in winter over Arctic regions. Increasing stratospheric water vapor will strengthen ozone depletion through the chemical process. However, ozone will increase in the middle stratosphere. The change in ozone due to increasing water vapor has an important effect on the stratospheric temperature change. © 2011 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

Li Z.-H.,Nanjing University of Information Science and Technology | Yang J.,Nanjing University of Information Science and Technology | Shi C.E.,Anhui Institute of Meteorological science | Pu M.-J.,Jiangsu Meteorological Bureau
Pure and Applied Geophysics | Year: 2012

Since the policy of "Reform and Open to the Outside World" was implemented from 1978, urbanization has been rapid in China, leading to the expansion of urban areas and population synchronous with swift advances in economy. With urban development underway, the urban heat island (UHI) and air pollution are being enhanced, together with vegetation coverage and relative humidity on the decrease. These changes lead to: (1) decline of annual fog days in cities (e.g. In Chongqing, so-called city of fog in China, the annual fog days have reduced from 100-145 in the 1950s to about 20-30 in the 2000s); (2) decrease in fog water content (FWC) and fog droplet size, but increase in fog droplets number concentration [e.g. Jinghong, a city in Yunnan province, the average FWC (the droplet diameter) during an extremely dense fog episode with drizzle was 0.74 g/m 3 (28.6 lm) during the 1968/69 winter and 0.08 g/m 3 (6.8 lm) in another extremely dense fog episode during the 1986/87 winter, correspondingly, the fog droplets number density had increased from 34.9 to 153 cm -3]; (3) decrease in fog water deposition (FWD) (e.g. the annual mean FWD measured in Jinghong had dropped from 17.3 mm in the 1950s to 4.4 mm in the 1970s and less than 1 mm in the 1980s, and no measurable FWD now.); (4) decrease in visibility in large cities (e.g. in Chongqing, the annual average visibility had decreased from 8.2-11.8 km in the 1960s to 4.9-6.5 km in the 1980s, and around 5 km in recent years); and (5) increase in the ion concentrations and acidity in fog water in urban areas [e.g. the average total ion concentration (TIC) in the center of Chongqing was 5.5 9 10 4 μmol/L, with mean pH value of 4.0, while the corresponding values are 9.7 9 10 3 μmol/L and over 5.5 in its rural area]. These changes endanger all kinds of transportation and human health. This paper summarized the authors' related studies, including observations and numerical simulations to confirm the above conclusions. © 2011 Springer Basel AG.

Shi C.,Anhui Institute of Meteorological science | Yang J.,Nanjing University of Information Science and Technology | Qiu M.,Anhui Institute of Meteorological science | Zhang H.,Anhui Institute of Meteorological science | And 2 more authors.
Atmospheric Research | Year: 2010

An unusually dense regional advection-radiation fog event over Anhui and the surrounding provinces in eastern China during Dec. 25-27, 2006, was investigated. At its mature stage, the fog covered most Anhui and parts of the surrounding provinces, reducing visibility to 100 m or less. It lasted more than 36 consecutive hours in some places. A mesoscale meteorological model (MM5), together with back-trajectory analysis, was used to investigate this fog event. The observations from a field station as well as hundreds of routine stations, along with two sets of visibility computing methods, were used to quantitatively and objectively validate the MM5 simulated liquid water content (LWC) and visibility. The verifications demonstrate that MM5 has a better fog predictability for the first day compared to the second day forecast, and better fog predictability compared to dense fog predictability with regard to the probability of detection (POD) and the threat score (TS). The new visibility algorithm that uses both LWC and number density of fog droplets significantly outperforms the conventional LWC-only based one in the fog prediction in terms of the POD score, especially for dense fog prediction. The objective verification in this work is the first time conducted for MM5 fog prediction, with which we can better understand the performance of simulated temporal and spatial fog coverage. The back-trajectory and sensitivity experiments confirm that subsidence and the steady warm and moist advections from southeast and southwest maintained the dense fog while the northwesterly dry wind resulted in dissipation of the fog. © 2009 Elsevier B.V. All rights reserved.

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