Spatial And Temporal Variations Of Atmosphere Angular Momentum And Torque And Their Relationship With Solar Activity

The Earth is a planet in the solar system,enveloped by the atmosphere.The progress of atmospheric general circulation which characterized the dynamic process of atmosphere has been always companied with the study of atmosphere angular momentum(AAM)budget.The angular momentum balance and transmission between the solid earth and the atmosphere directly affect the changes of the atmospheric circulation and climate.In this paper,atmospheric reanalysis data were used to calculate the atmospheric angular momentum and Torques for nearly 70 years.The AAM and Torques change in different spatial scales and time scales are analyzed in detail.The differences between reality value and theoretical value will be discussed.We use sunspot number(SN)data and Total Solar Irradiance(TSI)data to study the relationship between solar activity and AAM.And try to find possible physical mechanisms for climate change.The main conclusions are as follows:(1)In this paper,The AAM and Torques with high time precision and spatial resolution are calculated by NCEP/NCAR Reanalysis 1 from 1948 to 2015.During the study time,we find that the RAAM(relative atmosphere angular momentum),OAAM(omega atmosphere angular momentum),mountain torque and gravity wave torque show an increase trend.Friction torque shows a decrease trend.The total AAM is increase but total torque is decrease.On the seasonal scale,the RAAM,friction torque and mountain torque have great changes and they are significantly affected by the summer monsoon in northern hemisphere.However,OAAM and gravity wave torque have less change in different season.Above the time scale of year,the effect of friction torque on the angular momentum transfer between earth and atomsphere is greater than mountain torque or gravity wave torque.The Mountain Torques are mainly derived from the Qinghai-Tibet Plateau,the Andes and the Rocky Mountains,of which the Tibetan Plateau contributed the most.The friction torque and zonal wind speed have a high correlation,and the zonal wind in southern hemisphere is more important than northern hemisphere for friction torque.(2)In previous theoretical studies,the formula was deduced ideally with neglecting a lot of small variables.But in reality,those variables will be more and more important by time accumulation.In this paper,we analyzed the relationship between atmosphere angular momentum and torques by reanalysis data.The total torque which fixed by gravity wave torque is equal to the AAM derivative in short time scale.In decadal time scale,the total torque and the AAM can not be exactly the same even with the addition of the gravity wave torque.(3)The Earth is a closed system,in this way,the AAM will change with the angular momentum of solid earth through angular momentum transfer.We can study the atmosphere circulation and verify the calculation result by the changes of the earth rotation speed.In this paper,the relationship between the LOD and AAM will be discussed by IERS high-precision data.In the short time scale,the change of the Earth's rotation speed basically comes from the influence of the atamosphere.The correlation coefficient between AAM and LOD in seasonal scale is 0.91.As the time scale increases,the role of the atmosphere begins to weaken,and the correlation between AAM and LOD also begins to diminish.The direct correlation between total torque and LOD is not very high,but the cumulative value of friction torque has a good correlation with LOD.(4)After the previous research,we can know the distribution and variation of torque and AAM,understanding the relationship between AAM and atmospheric circulation.By linking solar activity with AAM,we can explain some of the solar and climate changes through atmospheric dynamics.The number of sunspots and TSI data will be used as a measure of solar activity.According to the difference analysis between the peak and bottom of sunspots number,we got some conclusion.In the years of intense solar activity,the RAAM,the OAAM and the mountain torque are larger than usual,while the friction torque is smaller than usual.Among them,the different between sunspot maximum year and minimum year is the most obvious in RAAM and friction torque.Through the correlation analysis of AAM and sunspots,we find that the AAM has the most significant response to the solar activity at 400hPa.