The Study Of Ionospheric Morphology Forcasting In East Asia During Magnetic Storms

Solar-terrestrial space is the main area for human space activities and peaceful space utilization,the fourth living environment closely related to human survival and development,as well as a strategic high ground for economic and social development,deep space exploration and national security.As an important part of the solar-terrestrial space environment,the ionosphere is located in the 60-1000 km altitude range of the atmosphere above the Earth,while ionospheric storms are important space weather phenomena those are propagated by solar activities through the solar-terrestrial space link and eventually act in the ionosphere.China is located in the East Asia region with a large spatial span.Therefore,the study of the spatial and temporal characteristics and forecasting methods of ionospheric storms in East Asia is of great scientific significance and application value for the stable development of economy and society,the implementation of the strategy of aerospace power and the intelligent construction of national defense information.As a discipline based on experiments and soundings,this paper starts from the statistical analysis of ionospheric data and physical mechanism,takes the basic theory that ionospheric storm is a space weather phenomenon based on ionospheric climatology as the entry point,and carries out systematic work and exploratory research on the spatial and temporal characteristics of ionospheric storm,such as the different response of topside-bottomside ionosphere during ionospheric storms and time delay of ionospheric storm to geomagnetic storms,and has achieved a series of results,which are briefly described as follows.First,the spatial and temporal characteristics of ionospheric TEC and Nm F2 in East Asia are systematically analyzed and compared using CODE GIMs data and COSMIC occultation data.The results show that the spatial and temporal characteristics of the ionospheric TEC and Nm F2 are generally consistent,but there are differences in the spatial and temporal scales,such as the solar activity has more influence on the ionospheric TEC than on the Nm F2,and the equatorial anomaly peaks at a higher latitude than the TEC anomaly peaks at the Nm F2.In addition,the climatology of the longitudinal differences of ionospheric TEC in the mid-latitudes of East Asia are systematically studied for the first time using CODE GIMs data with a temporal resolution of 1 h from 2015 to 2019,and the results show that the ionospheric TEC in the mid-latitudes of East Asia exhibits distinct longitudinal differences in high and low solar activity years.The physical mechanism is discussed in the context of the HWM-14 model,IGRF-2020 model and COSMIC occultation data.It is shown that the daytime longitude differences in the high solar activity years are mainly related to the different neutral wind/geomagnetic configurations in the east and west of the East Asian mid-latitudes,while the nighttime longitude differences are mainly related to the plasma vertical drift flux differences;the longitude differences in the low solar activity years may be related to the longitude differences in the background atmospheric mass density and other factors.Second,we systematically analyze the climatology of ionospheric slab thickness and its causes in these typical regions using TEC and Nm F2 data from Yakutsk,Beijing,and Guam stations located at high,mid,and low latitudes in East Asia from 2010 to 2017.We obtain a series of important results,and assess the effects of magnetic storms on ionospheric slab thickness in conjunction with the ionospheric slab thickness perturbation index DI.In addition,a case study attempted to explain why the effects of magnetic storms on ionospheric slab thickness in the Guam region are positively perturbed for most of the time period.During positive storms,the penetrating electric field together with the equatorial neutral wind lifts the ionosphere and causes a greater increase in TEC than in Nm F2(the top ionosphere TEC increases more than the bottom ionosphere TEC),while during negative storms the equatorial neutral wind lifts the electrons near the peak height at low latitudes to the topside ionosphere near the equatorial region,causing a smaller decrease in TEC than the decrease in Nm F2(bottom ionospheric TEC decreases more than top ionospheric TEC).And these causes together lead to the increase of ionospheric slab thickness in the Guam region during the storm.Thirdly,the differences and similarities in the topside-bottomside ionospheric response in the mid-latitude region of East Asia during two medium magnitude magnetic storms are investigated by using a combination of multi-source data such as GIMs,GPS-TEC,ionosonde hm F2,Nm F2,SWARM TEC,and TIEGCM model.The results show that the penetrating electric field and the enhanced equatorially oriented neutral wind during the August 15,2015 magnetic storm caused the TEC positive storm,but the lack of an effective ionization source at night made the positive ionospheric storm occur mainly in the top ionosphere;The positive ionospheric storm on November 10,2016 was mainly caused by the enhanced equatorward neutral wind at the time of the storm,and the presence of daytime photo-ionization allowed the top and bottom ionospheres to be continuously replenished with electrons at all heights while the overall ionosphere was lifted,which together formed the positive ionospheric storm.The importance of the ionospheric climatology in the formation of the topside-bottomside ionospheric response differences during the storms is confirmed.Fourth,based on TEC data from the low-latitude Taiwan Taoyuan Station,mid-latitude Beijing Station,and high-latitude Yakutia Station in East Asia,we systematically analyze the local time,seasonal,latitudinal characteristics of time delay of ionospheric storm to geomagnetic storms at different latitudes in East Asia,and analyze its relationship with magnetic storm intensity and solar activity at different latitudes in East Asia.Moreover,we have discussed the characteristics and drivers of pre-storm disturbance events.The results show that(1)It seems that the time delays of the positive storms are smaller for daytime MPO than those for night-time MPO(2)The seasonal characteristics of the time delay are highly correlated with the seasonal characteristics of TEC in different regions,indicating that some characteristics of ionospheric storms is extreme manifestations of ionospheric seasonal anomalies,and the time delay is one of the manifestations.(3)There is no relationship between the time delay and the corresponding magnetic storm intensity and the background solar activity,except that the negative storm shows a weak negative correlation with the solar activity.(4)The time delay increases nonlinearly with decreasing latitude,mainly due to the differences in the climatology of ionospheric TEC in different regions.(5)The polar region activity may be the driver of the mid-high latitude pre-storm disturbance events.In addition,the prolonged response delay events might belong to ionospheric Q perturbations.(6)Fifth,we explore the application of LSTM models in deep learning to the prediction of ionospheric TEC parameters and make the prediction of TEC parameters(quiet day and storm time)48 hours in advance.An empirical model for forecasting the ionospheric TEC for the next 1-48 hours is developed using the solar F10.7 index,sunspot number SSN,geomagnetic Dst index,geomagnetic time accumulation index ap(τ),solar wind speed Vz,and interplanetary southerly magnetic field component(IMF Bz)for the previous 6 days,and the results are compared with those of the traditional BPNN model.The results show that the LSTM model has lower forecast error and predicts the positive ionospheric storm much better than the BPNN model,which confirms the feasibility and superiority of using the deep learning method to forecast the ionospheric static day and storm time parameters.