拉尼娜状态下今冬气候如何？专家：可能出现冬春连旱

Group 1: La Niña Phenomenon - The La Niña phenomenon refers to the significant and sustained cooling of sea surface temperatures in the eastern and central equatorial Pacific Ocean, with China entering a La Niña state in October this year [1] - A La Niña state does not equate to a La Niña event; a La Niña event is recognized only when the NINO 3.4 index remains below -0.5 degrees Celsius for five consecutive months [1] - The probability of a double La Niña event occurring this winter is low, despite the ongoing La Niña state having some impact on China's climate [1] Group 2: Impact on Weather Patterns - La Niña directly influences weather by generating a cyclonic circulation anomaly over the Northwest Pacific and South China Sea, leading to prevailing northeast winds that suppress moisture transport to eastern and southern China [2] - This suppression may result in below-average precipitation in regions such as East and South China, with predictions indicating potential winter-spring droughts in these areas [2] Group 3: Freezing Rain and Its Effects - Freezing rain is a hazardous winter weather phenomenon where liquid rain freezes upon contact with surfaces below 0 degrees Celsius, creating ice that poses risks to transportation, power supply, and daily life [3] - The formation of freezing rain requires two key conditions: sufficiently low temperatures near the ground and the presence of precipitation, typically occurring when a warm layer exists above freezing temperatures [5] - Freezing rain can lead to significant hazards, including power line breakage and damage to vegetation, with rain ice (凇) being more destructive than fog ice (雾凇) due to its weight [7] Group 4: Regional Analysis of Freezing Rain - Guizhou Province experiences the highest frequency of freezing rain in China, with the peak season from December to February, although this winter's probability of widespread freezing rain is relatively low [10] - The average temperature in Guizhou is expected to be 7.1 degrees Celsius this winter, with a lighter incidence of freezing disasters compared to historical averages [10] - The distribution of freezing rain in Guizhou is influenced by its unique topography and stable weather systems, with higher occurrences in the western and central regions due to lower temperatures at higher altitudes [11]