NCEP/NCAR reanalysis data for the period of 1948–2017 were used to study the multidecadal variability of the hydrometeorological parameters (thermal, dynamic and humidity) in the Caspian Sea region. Polynomial approximations of the time series of the annual mean values indicated the non-linear nature and periodicity of the long-term variability of considered parameters. Three temporal intervals of duration 10–25 years with multidirectional trends of parameters changes are detected, which is considered as a manifestation of multidecadal variability. The North-Eastern wind regime prevails over the sea basin, with the major portion of heat advection into the region provided by zonal (Eastern) transport. Phases of air warming/cooling coincide with a weakening/strengthening of the Eastern wind transport. The time lag between the shift of dynamic and thermal (as well as humidity) regimes is about 6–8 years suggesting a leading role of the large-scale atmospheric forcing variations in the regional variability of thermal and humidity parameters. Specific humidity is positively correlated with air temperature and decreases/increases during periods of cooling/warming. In contrast, relative humidity and precipitation rate variations are negatively correlated with air temperature trends. Intensification of Eastern transport and associated cooling over the Caspian Sea coincide with a situation when the North Atlantic Oscillation (NAO) index decreases to negative values, and the East Atlantic-West Russian pattern (EAWR) index is significantly positive. On the contrary, weakening of the Eastern transport and warming occur during a period of sharp strengthening of the NAO, coinciding with strongly negative values of the EAWR index.

1948-2017年期间的NCEP / NCAR再分析数据用于研究里海地区水文气象参数（热，动态和湿度）的多年代际变化。年平均值时间序列的多项式逼近表明所考虑参数的长期变化的非线性性质和周期性。检测到三个持续时间为10–25年的时间间隔，这些时间间隔具有参数变化的多方向趋势，这被视为多年代际变化的体现。东北风在整个海盆中占主导地位，大部分热对流通过区域（东部）运输提供。空气变暖/冷却的阶段与东部风的减弱/加强相吻合。动态和热（以及湿度）状态转换之间的时间间隔约为6-8年，这表明大规模大气强迫在热和湿度参数的区域变化中起主导作用。比湿度与气温呈正相关，并且在制冷/保温期间会降低/增加。相反，相对湿度和降水率变化与气温趋势呈负相关。东部运输的加强和里海的相关降温与北大西洋涛动指数（NAO）下降至负值，而东大西洋西俄格局（EAWR）指数明显为正的情况相吻合。反之，