HAO 2011 Profiles In Science: Dr. Wenbin Wang

Contact:

Dr. Wenbin Wang is a Project Scientist II in the High Altitude Observatory of the National Center for Atmospheric Research. His main research interest is the coupling of the TIE-GCM with magnetospheric MHD models, including the development of high-resolution models of the thermosphere and ionosphere. He enjoys studying the dynamics and energetics of the thermosphere and ionosphere.

Publications

(1) Ma, R., J. Xu, W. Wang, and J. Lei. 2011: The effect of ~27-day solar rotation on ionospheric F₂ region peak densities (NmF₂), JGR-Space Physics, submitted.

Abstract: Ma et al. [2011] used ionospheric F₂-region peak electron densities (NmF₂) observed from 11 ionosonde stations in the East Asian/Australian sector from 1969 to 1986 to investigate the effect of ~27-day solar rotation on the ionosphere. These stations were located from the magnetically equatorial regions to the middle latitudes in both hemispheres. They found that, averaged over all stations and for 18 years, the normalized standard deviation of the midday ~27-day variations of NmF₂ was 8% and that of the midnight was 10%. They applied different data analysis methods, including Fourier transform, band pass filter and multiple linear regression analysis, to determine quantitatively the sources of the observed ~27-day variations of NmF₂ and their relative contributions to these variations. Their results show that the ~27-day variations in solar radiation and geomagnetic activity, caused by solar rotation, are the main drivers of the ionospheric ~27-day variations. They accounted for more than 85% of the variations seen in the NmF₂ ~27-day variation, and their contributions became about 95% at higher latitudes. At geomagnetically low latitudes, the contribution of the ~27-day variation in solar EUV radiation was greater than that of the ~27-day variation in geomagnetic activity. However, the contribution from geomagnetic activity became more significant and was even larger than the contribution of solar radiation at higher latitudes, especially at midnight. At all latitudes the correlation between the ~27-day variations of NmF₂ and solar radiation was evidently positive, whereas that between NmF₂ and geomagnetic activity was positive at geomagnetically low latitudes, and became negative at higher middle latitudes. They did not found large seasonal or solar cycle changes in the ~27-day variations of NmF₂. These variations, however, did show significant hemispheric asymmetry.

(2) Xu, Jiyao, Ruiping Ma, and Wenbin Wang. 2011: Ter-annual variation in the F₂-layer peak electron density (NmF₂) at middle latitudes, JGR-Space Physics, submitted.

Figure 2: High resolution

Abtract: Ionosonde data from 33 stations in three longitude sectors from 1969–1986 have been used to study the seasonal variations of ionospheric F₂-layer peak electron densities (NmF₂). We found that there is a periodic oscillation in daytime NmF₂ with a period of 4 months (ter-annual). Our analysis shows that there is a very good phase match between the annual and semi-annual oscillations and the ter-annual oscillations. These three oscillations vary with solar activity in the same way: large amplitudes during solar maximum. The amplitude of the ter-annual oscillation is also correlated with the product of the amplitudes of annual and semi-annual oscillations. These suggest that the ter-annual oscillation might be related to the nonlinear interaction between the annual and semi-annual oscillations. In addition, the ter-annual oscillation is stronger in the midlatitude region in the north hemisphere than in the south hemisphere. Furthermore, there are large differences in the ionospheric seasonal variations between daytime and nighttime. No obvious ter-annual oscillation signature is seen in the nighttime F₂-layer.

Figure 2 caption: Temporal variations of the amplitudes of annual, semi-annual and ter-annual oscillations (upper panel) and their phases (middle panel) of daytime NmF₂ at 4 stations in the Asian sector. The lower panel shows scatter points of the amplitudes of the ter-annual oscillation with the square root of the multiplication of the amplitudes of the semi-annual and annual oscillations. The temporal variation of F_10.7 is also given in the upper panel.