Hebei Key Laboratory for Meteorology and Eco environment

Shijiazhuang, China

Hebei Key Laboratory for Meteorology and Eco environment

Shijiazhuang, China
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Chen X.,Xinjiang Institute of Ecology and Geography | Chen X.,Hebei Key Laboratory for Meteorology and Eco environment | Wei W.,Institute of Desert Meteorology | Liu M.,Xinjiang Institute of Ecology and Geography | Liu M.,Chinese Academy of Sciences
Meteorological Applications | Year: 2013

The temperature of snow at 10 discrete vertical levels in the snow pack was measured using automatic temperature recorders at 10 min intervals following 5 snowfalls between January and March 2009 at the Tianshan Station for Snow Cover and Avalanche Research. The amplitude of the diurnal fluctuation in the temperature during the measurement run of 10 March 2009, when the snow was melting, was 1.85 times greater than during the measurement run of 15 February, when snow was accumulating. Analysis of the vertical temperature gradient for all five measurement runs shows that the temperature gradient of the snow was at a maximum value at the snow surface. The maximum snow temperature gradient was measured during the run of 21 January and was 4.46 times greater than during the run of 15 February. The temperature gradient was approximately zero 30 cm below the snow surface. Analysis of the characteristics of the snow temperature and the daily mean volumetric moisture content of the snow leads to the conclusion that the snow cover in the western Tianshan Mountains can be divided into stable, interim, and melting stages. A critical snow volumetric moisture content of 0.1% separates the stable and interim stages, while a volumetric moisture content of 0.3% separates the interim and melting stages. © 2012 Royal Meteorological Society.


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).


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.

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