Delta distribution of electronegative plasma predicted by reformed“spring oscillator”dynamic equation with dispersing force

In our relevant paper[Zhao S X(2021)Chin.Phys.B 30055201],a delta distribution of negative ions is given by fluid simulation and preliminarily explained by decomposed anions transport equation.In the present work,first,the intrinsic connection between the electropositive plasma transport equation and spring oscillator dynamic equation is established.Inspired by this similarity,reformed“spring oscillator”equation with dispersing instead of restoring force that gives quasi-delta solution is devised according to the math embodied in the anion equation,which is of potential significance to the disciplines of atomic physics and astronomy as well.For solving the“diffusion confusion”the physics that determines the delta profile within the continuity equation is explored on the basis that recombination loss source term plays the role of drift flux,which is applicable for fluid model of low temperature plasma,but not the ordinary fluid dynamics.Besides,the math and physics revealed in this work predict that the ratio of recombination or attachment(for electrons)frequency versus the species diffusion coefficient is a very important parameter in determining the delta distribution,as it acts as the acceleration of object,according to the reformed oscillator equation.With this theory,the analogous delta profile of electrons density in the famous drift and ambi-polar diffusion heating mechanism of electronegative capacitively coupled plasma is interpreted.

On the Weakened Relationship between Spring Arctic Oscillation and Following Summer Tropical Cyclone Frequency over the Western North Pacific:A Comparison between 1968–1986 and 1989–2007

This study documents a weakening of the relationship between the spring Arctic Oscillation （AO） and the following summer tropical cyclone （TC） formation frequency over the eastern part （150°-180°E） of the western North Pacific （WNP）. The relationship is strong and statistically significant during 1968-1986, but becomes weak during 1989-2007. The spring AO- related SST, atmospheric dynamic, and thermodynamic conditions are compared between the two epochs to understand the possible reasons for the change in the relationship. Results indicate that the spring AO leads to an E1 Nifio-like SST anomaly, lower-level anomalous cyclonic circulation, upper-level anomalous anticyclonic circulation, enhanced ascending motion, and a positive midlevel relative humidity anomaly in the tropical western-central Pacific during 1968-1986, whereas the AOrelated anomalies in the above quantities are weak during 1989-2007. Hence, the large-scale dynamic and thermodynamic anomalies are more favorable for TC formation over the eastern WNP during 1968-1986 than during 1989-2007.

Unstable relationship between spring NAO and summer tropical cyclone genesis frequency over the western North Pacific

The present study reveals the fact that the relationship between the spring(April–May)North Atlantic Oscillation(NAO)and the following summer(June–September)tropical cyclone(TC)genesis frequency over the western North Pacific(WNP)during the period of 1950–2018 was not stationary.It is shown that the relationship between the two has experienced a pronounced interdecadal shift,being weak and insignificant before yet strong and statistically significant after the early 1980 s.Next we compare the spring NAO associated dynamic and thermodynamic conditions,sea surface temperature(SST)anomalies,and atmospheric circulation processes between the two subperiods of 1954–1976 and 1996–2018,so as to illucidate the possible mechanism for this interdecadal variation in the NAO-TC connection.During the latter epoch,when the spring NAO was positive,enhanced low-level vorticity,reduced vertical zonal wind shear,intensified vertical velocity and increased middle-level relative humidity were present over the WNP in the summer,which is conducive to the genesis of WNP TCs.When the spring NAO is negative,the dynamic and thermodynamic factors are disadvantageous for the summertime TC formation and development over the WNP.The results of further analysis indicate that the persistence of North Atlantic tri-pole SST anomalies from spring to the subsequent summer induced by the spring NAO plays a fundamental role in the linkage between the spring NAO and summer atmospheric circulation.During the period of 1996–2018,a remarkable eastward propagating wave-train occurred across the northern Eurasian continent,forced by the anomalous SST tri-pole in the North Atlantic.The East Asian jet flow became greatly intensified,and the deep convection in the tropics was further enhanced via the changes of the local Hadley circulation,corresponding to a positive spring NAO.During the former epoch,the spring NAO-induced tri-pole SST anomalies in the North Atlantic were non-existent,and the related atmospheric circulation anomalies were extremely weak,thereby leading to the linkage between spring NAO and WNP TC genesis frequency in the following summer being insignificant.

A New Prediction Model for Grain Yield in Northeast China Based on Spring North Atlantic Oscillation and Late-Winter Bering Sea Ice Cover

Accurate estimations of grain output in the agriculturally important region of Northeast China are of great strategic significance for guaranteeing food security.New prediction models for maize and rice yields are built in this paper based on the spring North Atlantic Oscillation index and the Bering Sea ice cover index.The year-to-year increment is first forecasted and then the original yield value is obtained by adding the historical yield of the previous year.The multivariate linear prediction model of maize shows good predictive ability,with a low normalized root-mean-square error（NRMSE）of 13.9%,and the simulated yield accounts for 81%of the total variance of the observation.To improve the performance of the multivariate linear model,a combined forecasting model of rice is built by considering the weight of the predictors.The NRMSE of the model is 12.9%and the predicted rice yield explains 71%of the total variance.The corresponding cross-validation test and independent samples test further demonstrate the efficiency of the models.It is inferred that the statistical models established here by applying year-to-year increment approach could make rational prediction for the maize and rice yield in Northeast China before harvest.The present study may shed new light on yield prediction in advance by use of antecedent large-scale climate signals adequately.