Vulnerability Assessment of Snow Disaster Based on Traffic System:A Case Study of Chenzhou City in Hunan Province,China

The article establishes the patterns of urban snow disaster system and disaster chain based on the theory of regional disaster system. The patterns indicate that urban snow disaster is exacerbated mainly through the traffic system. In addition, the paper sets up the vulnerability assessment index system and synthetically vulnerability assessment model of urban snow disaster which are mainly based on traffic system, and applies them in Chenzhou City. The results of assessment indicate that obvious geographical differences exist in the vulnerability of snow disaster bearing bodies: vulnerability of Chenzhou section of the Beijing-Zhuhai expressway is the highest in Chenzhou City, and the southeastern counties are more vulnerable than the northwest region. Furthermore, according to the snow disaster vulnerability dynamic process analysis, the vulnerability of Chenzhou City obviously increased in 2008 winter compared with that in 2007. Finally, the paper presents some suggestions for the locations of the emergency commands and the reserves of relief materials based on the evaluation results, and points out that disaster monitoring and relevant technical level should be strengthened for the minimization of traffic system's vulnerability.

Early Warning of Snow Disaster in Pasturing Areas of Inner Mongolia

Using ground and remote sensing monitoring, and national standards of snow disaster monitoring evaluation standards, quantitative evaluation of snow disaster was realized. Threshold of animal husbandry weather forecast indexes were applied to establish snow disaster early warning for different grasslands in pasturing areas of Inner Mongolia, and make the grade distribution map of snow disaster early warning. The forecast results basically met the real conditions, it proved that this forecast method was capable of evaluating scale and influence degree of snow disaster. However, the snow disaster grade forecast deviated from the real conditions for the influence of weather forecast accuracy rate.

Risk analysis of snow disaster in the pastoral areas of the Qinghai-Tibet Plateau

Snow disaster is one of the top ten natural disasters worldwide, and the most se- vere natural disaster to affect the pastoral areas of the Qinghai-Tibet Plateau. Based on the hazard harmfulness data collected from historical records and data collected from entities affected by this hazard in 2010, a comprehensive analysis of the 18 indexes of snow disaster on the Qinghai-Tibet Plateau was conducted, encompassing the hazard harmfulness, the amount of physical exposure the hazard-bearing entities face, the sensitivity to the hazard, and the capacity to respond to the disaster. The analysis indicates that： （1） areas at high-risk of snow disaster on the Qinghai-Tibet Plateau are located in certain areas of the counties of Yecheng and Pishan in the Xinjiang region; （2） areas at medium-risk of snow disaster are found between the Gangdise Mountains and the Himalayas in the central-western part of the Qinghai-Tibet Plateau, and the southeastern part of the southern Qinghai Plateau; （3） the risk of snow disaster is generally low throughout the large area to the south of 30°N and the re- gion on the border of the eastern Qinghai-Tibet Plateau. Overall, the risk of snow disaster in high-altitude areas of the central Qinghai-Tibet Plateau is higher than that at the edge of the plateau.

Indications of stratospheric anomalies in the freezing rain and snow disaster in South China,2008

NCEP/NCAR reanalysis data were used to characterize stratospheric temperature and water-vapor anomalies before and after the freezing rain and snow disaster of South China in 2008,and the influence of stratospheric circulation anomalies on the troposphere.Stratospheric temperature and water-vapor anomalies provided good leading indicators of this weather event.The period from December 1st 2007 to February 28th 2008 was divided into 18 pentads.During the 6th pentad,temperature decreased significantly at 10 hPa in the near-polar stratospheric region,and the decreasing trend strengthened and extended downward and southward to middle and lower latitudes.During the 14th-18th pentads,the temperature decrease reached its maximum and extended to 30°N.This coincided with the widespread freezing rain and snow event.By the end of January 2008,the temperature decrease ended in the near-polar stratospheric region,but continued in the mid-latitude area of the troposphere as the freezing rain and snow weather persisted.Similar to the temperature variations,positive anomalies of relative humidity in the stratospheric near-polar region also strengthened and extended downward and southward,coinciding with the freezing rain and snow event.Along with the significant relationship between the freezing rain and snow disaster and stratospheric circulation anomalies,the stratospheric polar vortex changed its shape in late December,intensifying and spreading downward from the top of the stratosphere and southward to the Asian continent,resulting in a deepening of the East Asian Trough and a strengthening of meridional circulation.Before the occurrence of the freezing rain and snow event,temperature and vapor increases in the stratosphere transferred downward to the troposphere,along with a stratospheric flow in the near-polar region southward to lower latitudes.

The Large Scale Circulation of the Snow Disaster in Southern China in the Beginning of 2008

This study analyzed the heaviest snowfalls or icy-rainfalls occurring in southern China from January to the beginning of February 2008.The results are summarized as follows：the disaster was induced by the persistent front of warm/cold air masses in southern China,which displayed an interaction between the weather systems in higher and lower latitudes.There was an adjustment for circulation at hemisphere scale during mid January by a variation of sign of the Arctic Oscillation（AO）index from negative to positive.The long lasting precipitation well coincided with a blocking situation centered near 80°E from mid January to the beginning of February.A diagnostic analysis indicates that stationary waves with an energy dispersion accompanying the blocking high propagated from upstream region in high latitudes to the south of the Yangtze River,which formed a maintaining energy source for the cyclonic circulation in situ.This resulted in that the large mass of cold air in high latitudes could not easily invade into the south but slowly shifted southward.On the other hand,the sea surface temperature（SST）over the warm pool of the western Pacific increased with a new history record due to the effect of the strong La Nina episode,which also blocked the cold air mass from the north.The blocking high collapsed around 30 January and the energy source for the local cyclonic circulation was cut off.Thus,the precipitation in southern China ceased after 1 February.

NUMERICAL SIMULATION OF SSTA IMPACTS OVER THE GLOBAL OCEAN ON THE ANOMALOUS CIRCULATION OVER EURASIA IN JANUARY 2008

In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies （SSTAs） over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the North Atlantic. Our results are shown as follows： （1） CAM3.0, driven by the combined SSTAs over the four oceanic regions, can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008, indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia. （2） The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough. However, the influence of the SSTAs over individual oceanic regions differed from one another in other aspects. The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height （Z500A） over the middle-high latitudes and had a somewhat smaller effect over the low latitudes. For the warm SSTAs over Kuroshio, the subtropical high was much stronger, spread farther north than usual, and had an anomalous easterly that dominated the northwest Pacific Ocean. The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia, a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region. Because of the La Nifia event, the winter monsoon was stronger than normal, with an anomalously cooler northerly over the southeastern coastal areas of China. （3） The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAS. This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008, especially the atmospheric circulation anomalies over the subtropics, which were more similar to those of the winter E1 Nifio events than to the circulation anomalies following La Nifia.

Changes in the food supply capacity of alpine grassland ecosystem:A dialectic synthesis of natural and anthropogenic drivers

Grassland-based animal husbandry and livestock production is the main contributor to livelihood creation for herdsmen.By using the structural dynamics method,this study quantified the changes in the food supply capacity(FSC)of alpine grassland ecosystem and sensitivity to significant variables.The findings indicated that:i)Natural factors were the dominated forces affecting FSC,and their contribution was 71.3%.Of these natural elements,the net primary productivity(NPP)and precipitation were the largest contributors,accounting for approximately 35%.The sensitivity index of the FSC to NPP and precipitation during grassland growing season were 4.1 and 1.9 respectively.On the contrary,human factors like warm shed area,density of road,capacity for access to information,contributed to 28.7%of the total FSC.ii)More intense snow disaster had a larger negative impact on FSC.Snow disaster can cause dramatic reduction in FSC,with a loss rate of 27.6%and with none intense disaster more negative impacts,iii)The continuing increase of FSC in the past 30 years from 1984 to 2014 was due to the significant increase of precipitation and NPP in the growing season of alpine grassland.Evidently,successful adaptation to climate change was critical to combat the climatic adversely impact on FSC.Typically,strengthening information dissemination,road accessibility and knowledge popularization of local residents'disaster reduction should be place high priority for improving FSC。