1961—2015年中国饱和水汽压差的时空变化特征

Spatio-temporal variations of vapor pressure deficit in China from 1961 to 2015

摘要:

饱和水汽压差(vapor pressure deficit,VPD)是指示地区大气干燥程度的重要指标,探究我国各地区VPD时空变化特征对气候变化研究和实际农牧业生产等具有重要意义。基于全国772个气象站日平均气温和日相对湿度等资料,采用协同克里金插值、Mann-Kendall趋势检验和偏相关分析等方法,对中国1961—2015年饱和水汽压差的时空分布及变化趋势特征进行分析,并讨论了VPD与气温和相对湿度的关系。结果表明:1961—2015年中国VPD时空分布差异显著,时间上呈现夏高冬低的特征,空间上年均VPD高值主要集中在西北干旱半干旱区,低值主要分布在东北地区、青藏地区以及南方部分地区。全国绝大部分地区VPD呈升高趋势,以2000年为突变点,平均升高趋势由1.519 6 hPa/(10 a)增长到7.074 3 hPa/(10 a)。南方地区与北方地区VPD变化的主导因子均是最高气温,而西北地区和青藏地区VPD变化的主导因子分别为平均气温和相对湿度;四个地区突变年前后VPD变化的主导因子保持不变。

Abstract:

Vapor pressure deficit (VPD) is a critical meteorological variable with significant implications for hydrology,ecology,and climate change.Numerous studies have demonstrated that VPD,a key indicator of atmospheric dryness,has undergone substantial changes in response to global climate warming.Investigating the spatiotemporal variations of VPD across different regions of China is essential for advancing climate change research and supporting agricultural and pastoral practices.While regional-scale VPD studies have been conducted by domestic scholars,comparative analysis of VPD changes at the national scale remain limited.This study uses daily mean air temperature and relative humidity data from 772 meteorological stations across China,applying Tetens' empirical formula to calculate VPD.Through co-Kriging interpolation,Mann-Kendall trend tests,and correlation and partial correlation analyses,the spatiotemporal variability and trends of VPD across different time scales and geographical regions from 1961 to 2015 were examined.Additionally,the study explores the relationships between VPD,temperature,and relative humidity,identifying the dominant factors influencing VPD changes over different periods.The results indicate significant spatiotemporal variation in VPD across China from 1961 to 2015,with higher values in summer and lower values in winter.Spatially,high annual average VPD values were concentrated in the arid and semi-arid regions of Northwest China,while lower values were found in Northeast China,the Qinghai-Xizang Plateau,and parts of the southern region.The annual average VPD across China ranged from 0.127 kPa to 1.547 kPa,with an overall average of 0.526 kPa.Most regions showed an increasing VPD trend over time.Between 1961 and 1999,57％ stations exhibited increasing VPD trends,and this proportion rose to 67％ between 2000 and 2015,with the year 2000 identified as a mutation point.The average VPD increase accelerated from 1.519 6 hPa/(10 a) to 7.074 3 hPa/(10 a) after 2000.Correlation and partial correlation analyses revealed that VPD was significantly positively correlated with temperature and negatively correlated with relative humidity in all regions.Maximum temperature was the dominant factor driving VPD changes in southern and northern China,while average temperature and relative humidity played a greater role in the Northwest and Qinghai-Xizang regions.These dominant factors remained consistent before and after the mutation point.While the primary factors influencing VPD changes were explored,further investigation is needed to assess the impact of other potential factors such as topography,vegetation cover,and broader climatic conditions.This study provides insights into the characteristics and drivers of VPD changes across seasons and regions,offering a scientific foundation for climate-ecological and vegetation modeling studies and valuable guidance for policy-makers and relevant stakeholders.