Hao L.,Hebei Climate Center
2011 International Conference on Remote Sensing, Environment and Transportation Engineering, RSETE 2011 - Proceedings | Year: 2011
Based on Reanalysis datasets from NCEP/NCAR and summer rainfall datasets from China National Climate Center (NCC), by using trend analysis and composite analysis methods, the reasons causing summer precipitation in North China to reduce was investigated. The results show that summer rainfall in North China had a significant decreasing tendency, especially true since 1965 in which an abrupt change occurred. The northern hemisphere atmospheric circulation at 500 hPa had a remarkable change after 1965, from outstanding meridional circulation to outstanding zonal circulation, leading to upper trough activity to decrease, resulting in the rainfall weather processes caused by upward motion behind trough significantly to reduce. At 500 hPa in Mongolian region, air temperature decreased, resulting in lower troposphere pressure to increase, leading to low pressure activity significantly to decrease and rainfall weather processes influencing North China to reduce. At the same time, the decreased air temperature in 500hPa would caused the upper troposphere geopotential height to reduce, resulting in high-altitude jet southerly location, the East Asian summer monsoon to weaken, then it was difficult for water vapor transport to cross the Yangtze River valley and reach the North China region, with a southerly summer monsoon rainfall zone. The summer precipitation reduction in North China had a good correlation with the northern hemispheric circulation changes. © 2011 IEEE.
Shi X.,CAS Institute of Atmospheric Physics |
Shi X.,Hebei Key Laboratory for Meteorology and Eco environment |
Shi X.,Hebei Climate Center |
Wang B.,CAS Institute of Atmospheric Physics |
And 2 more authors.
Advances in Atmospheric Sciences | Year: 2013
A two-moment bulk stratiform microphysics scheme, including recently developed physically-based droplet activation/ice nucleation parameterizations has been implemented into the Grid-point Atmospheric Model of IAP LASG (GAMIL) as an effort to enhance the model's capability to simulate aerosol indirect effects. Unlike the previous one-moment cloud microphysics scheme, the new scheme produces a reasonable representation of cloud particle size and number concentration. This scheme captures the observed spatial variations in cloud droplet number concentrations. Simulated ice crystal number concentrations in cirrus clouds qualitatively agree with in situ observations. The longwave and shortwave cloud forcings are in better agreement with observations. Sensitivity tests show that the column cloud droplet number concentrations calculated from two different droplet activation parameterizations are similar. However, ice crystal number concentration in mixed-phased clouds is sensitive to different heterogeneous ice nucleation formulations. The simulation with high ice crystal number concentration in mixed-phase clouds has less liquid water path and weaker cloud forcing. Furthermore, ice crystal number concentration in cirrus clouds is sensitive to different ice nucleation parameterizations. Sensitivity tests also suggest that the impact of pre-existing ice crystals on homogeneous freezing in old clouds should be taken into account. © 2013 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.
Shi X.,University of Wyoming |
Shi X.,Hebei Key Laboratory for Meteorology and Eco environment |
Shi X.,Hebei Climate Center |
Liu X.,University of Wyoming |
Zhang K.,Pacific Northwest National Laboratory
Atmospheric Chemistry and Physics | Year: 2015
In order to improve the treatment of ice nucleation in a more realistic manner in the Community Atmosphere Model version 5.3 (CAM5.3), the effects of pre-existing ice crystals on ice nucleation in cirrus clouds are considered. In addition, by considering the in-cloud variability in ice saturation ratio, homogeneous nucleation takes place spatially only in a portion of the cirrus cloud rather than in the whole area of the cirrus cloud. Compared to observations, the ice number concentrations and the probability distributions of ice number concentration are both improved with the updated treatment. The pre-existing ice crystals significantly reduce ice number concentrations in cirrus clouds, especially at mid- to high latitudes in the upper troposphere (by a factor of ∼10). Furthermore, the contribution of heterogeneous ice nucleation to cirrus ice crystal number increases considerably. Besides the default ice nucleation parameterization of Liu and Penner (2005, hereafter LP) in CAM5.3, two other ice nucleation parameterizations of Barahona and Nenes (2009, hereafter BN) and Kärcher et al. (2006, hereafter KL) are implemented in CAM5.3 for the comparison. In-cloud ice crystal number concentration, percentage contribution from heterogeneous ice nucleation to total ice crystal number, and pre-existing ice effects simulated by the three ice nucleation parameterizations have similar patterns in the simulations with present-day aerosol emissions. However, the change (present-day minus pre-industrial times) in global annual mean column ice number concentration from the KL parameterization (3.24 × 106 mg-2) is less than that from the LP (8.46 × 106 mg-2) and BN (5.62 × 106 mg-2) parameterizations. As a result, the experiment using the KL parameterization predicts a much smaller anthropogenic aerosol long-wave indirect forcing (0.24 W mg-2) than that using the LP (0.46 W m-2) and BN (0.39 W mg-2) parameterizations. © 2015 Author (s).
Li X.,Nanjing University of Information Science and Technology |
Li X.,National Climate Center |
Gemmer M.,National Climate Center |
Zhai J.,National Climate Center |
And 3 more authors.
Quaternary International | Year: 2013
In this paper, the spatio-temporal variation and trend of daily actual evapotranspiration (ETa) are calculated for the Haihe River Basin from 1961 to 2010. The methodology is based on the complementary relationship approach, i.e. the advection-aridity (AA) model with parameter validation from 1961 to 2010, which allows the determination of ETa that cannot be instrumentally measured. Daily data on mean/maximum/minimum temperature, air pressure, actual water vapor pressure, sunshine hours, wind speed, sunshine duration and cloud cover from 31 meteorological stations from 1961 to 2010 are used in order to identify the main drivers of changes in evapotranspiration. The trend tests applied in this study are the linear regression method and the nonparametric Mann-Kendall test (MKtest). The results show: 1) the Haihe River Basin has an annual ETa at about 484mm/yr. The highest ETa occurs in summer, followed by autumn. From 1961 to 2010, the annual ETa, the ETa in summer and the ETa in autumn show a significant negative trend in the Haihe River Basin. The ETa varies insignificantly in spring and winter; 2) the ETa shows distinct spatial variability in the Haihe River Basin. It closely follows the topography and increases with greater distance from the sea, but varies significantly during the seasons; 3) the central plain area of the Basin around the capital city of Beijing shows the highest occurrence of negative trends of ETa with a decrease of ETa of 40mm for the time series. 4) negative trends of ETa in summer are related to multiple factors: decreasing relative humidity and decreasing reduced sunshine duration under increasing surface temperatures in summer. Increases in surface temperature include the mean, maximum and minimum daily temperature. The decline of ETa in autumn can be explained by a negative trend of relative humidity. The decreasing ETa suggests a reduction in water availability and cycle in seasons with highest water demand. © 2013 Elsevier Ltd and INQUA.
Hao L.-S.,Nanjing University of Information Science and Technology |
Min J.-Z.,Hebei Climate Center |
Ding Y.-H.,National Climate Center
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2011
Based on the daily precipitation data of 1961-2008 from 37 meteorological stations and NCEP, ECMWF reanalysis grid data, the precipitation events change and rainstorm events reduction occurred in North China were analyzed. The results show that mid-summer rainstorm event has a great impact on the summer precipitation and annual precipitation in North China during recent 50 years. Mid-summer rainstorm events showed significant linear decreasing trend, which was related with water vapor flux reduction into North China through the south border caused by the weakening of East Asian summer monsoon. In addition, mid-summer rainstorm events reduction is also well correlated with the weakening of India convection and the enhancing of Philippine convection, as well as the weakening of 125° E cross-equatorial flow and the strengthening of 145° E cross-equatorial flow. This provides an understanding of precipitation reduction in North China.
Dai L.-Q.,Hebei Institute of Meteorological Science |
Dai L.-Q.,Hebei Key Laboratory for Meteorology and Eco environment |
Kang X.-Y.,Hebei Institute of Meteorological Science |
Kang X.-Y.,Hebei Key Laboratory for Meteorology and Eco environment |
And 6 more authors.
Chinese Journal of Ecology | Year: 2014
Based on the data of daily meteorological factors in winter, winter wheat freezing injury and winter wheat cultivars in Hebei Province from 1981 to 2010, the three types of climatic indexes of winter wheat freezing injury, including severe temperature downing in early winter, winter with long cold days and freeze-thawing, were established by using rank sum test and Bayesian discriminant analysis. According to the risk analysis principle and probability density function, the climatic models of risk probability index for winter wheat freezing injury were set up, and the freezing risk of winter wheat in Hebei was assessed. The results showed that the freezing injury due to severe temperature downing in early winter was affected mainly by the variation range of temperature and the extreme minimum temperature during the temperature downing process. The freezing injury due to winter with long cold days was influenced mainly by the cold intensity of winter season, including the number of days of winter wheat overwintering stage, the mean temperature, the number of days with the minimum temperature being lower than the critical temperature, and the accumulated negative temperature during the same period. The freezing injury due to freeze-thawing was affected mainly by the extreme minimum temperature in the microthermal process with daily average temperature above 0 °C. The major risk of winter wheat freezing injury in the north Hebei was due to winter with long cold days, and the high and sub-high risks of such freezing injury mainly occurred in the middle-north part of Tangshan and Qinhuangdao and northwest of Baoding. The main risk of winter wheat freezing injury in the middle and south Hebei was freeze-thawing and severe temperature downing in early winter, and the high and sub-high risks of such freezing injury mainly occurred in the east part of Xingtai and Handan, and north-west part of Baoding. © 2014, Editorial Board of Chinese Journal of Ecology. All rights reserved.
Li S.,CAS Institute of Atmospheric Physics |
Li S.,Joint Center for Global Change Studies |
Jing Y.,CAS Institute of Atmospheric Physics |
Jing Y.,Hebei Climate Center |
Luo F.,CAS Institute of Atmospheric Physics
Science China Earth Sciences | Year: 2015
One recent study by using instrumental records suggested the correlation between East Asian surface air temperatures (EATs) and the Atlantic Multidecadal Oscillation (AMO) reaches the maximum when the former leads the latter by 5–7 years. This seems to disagree with a previous well-realized point that the AMO modulates the decadal variation of EATs, since the atmosphere responds swiftly to sea surface temperature anomalies (SSTA) if therein. It implies that the AMO-EATs correlation should reach the maximum when they are simultaneous or the AMO leads EATs slightly, rather than that the EATs lead the AMO. Thus, this poses an issue about the reality of the newly found lead-lag correlation. Because the instrumental record in the natural climate system may be contaminated by human activities, the EATs-AMO lead-lag correlation derived from the instrumental records may not be a realistic connection of the natural climate system. Thus, whether the connection also exists in the proxies prior to the industrial is essential to answer the issue. In this study the EATs-AMO lead-lag connection is analyzed by using the reconstructed data in the last 500 years, together with the control experimental data with the prescribed pre-industrial forcing in a multiple of coupled climate system models, which attend the international CMIP5 program. The results suggest that the connection, the EATs lead the AMO, also exists in the period from the Little Ice Age (LIA) to the industrial, 1500–1860AD. Therefore, the connection may be realistic in the natural climate system. The mechanisms for the connection are then discussed briefly. The results from this paper provide some insights into the connection of the AMO with East Asian climate. © 2015 Science China Press and Springer-Verlag Berlin Heidelberg
Chai D.-H.,Hebei Meteorological Observatory |
Chai D.-H.,Hebei Eco Environmental Monitoring Laboratory |
Yang X.-L.,Hebei Meteorological Observatory |
Li J.-B.,Hebei Meteorological Observatory |
And 4 more authors.
Journal of Natural Disasters | Year: 2010
In the late December 2007, the greenhouse vegetables underwent serious damage over the central and southern plains of Hebei Province, leading to a considerable reduction of vegetable production. The main weather environment causing this disaster is the persistent heavy frog, which resulted from the long-duration of high humidity , lack of sunshine and low temperature. The high level westerly wind, preventing the cold air from high latitude intruding the plain, and the cold air spreading from the surface high pressure are suitable for the formation of heavy fog. In the early stage of the heavy fog, the low - level southerly wind, the water vapor convergence and the lowlevel shear provided good water vapor condition for the fog. The formation and maintenance of the temperature inversion produce the favorable stratification condition. Small northerly wind at night and little cloud are suitable for the formation of droplet. The strong cold air intrusion is the main cause for the persistent heavy fog. This work presents key points for persistent fog prediction and the disaster prevention measures for greenhouses vegetables.