Qinzeng Li

Concentric gravity waves over northern China observed by an airglow imager network and satellites

The first no-gap OH airglow all-sky imager network was established in northern China in February 2012. The network is composed of six all-sky airglow imagers that make observations of OH airglow gravity waves and cover an area of about 2000 km east and west and about 1400 km south and north. An unusual outbreak of Concentric Gravity Wave (CGW) events were observed by the network nearly every night during the first half of August 2013. These events were coincidentally observed by satellite sensors from Fengyun-2 (FY-2), Atmospheric Infrared Sounder (AIRS)/Aqua, and Visible Infrared Imaging Radiometer Suite (VIIRS)/Suomi National Polar-orbiting Partnership (NPP). Combination of the ground imager network with satellites provides multilevel observations of the CGWs from the stratosphere to the mesopause region. In this paper, two representative CGW events in August 2013 are studied in detail: first is the CGW on the night of 13 August 2013, likely launched by a single thunderstorm. The temporal and spatial analyses indicate that the CGW horizontal wavelengths follow freely propagating waves based on a GW dispersion relation within 300 km from the storm center. In contrast, the more distant observed gravity wave field exhibits a smaller horizontal wavelength of ~20 km, and our analysis strongly suggest this wave field represents a ducted wave. A second event, exhibiting multiple CGWs, was induced by two very strong thunderstorms on 9 August 2013. Multiscale waves with horizontal wavelengths ranging from less than 10 km to 200 km were observed.

Asymmetry of solar activity in cycle 23

Using sunspot groups and sunspot areas from May 1996 to February 2007, we find that solar activity for cycle 23 is dominant in the southern hemisphere, and our results enhance the inferred but uncertain conclusions obtained before. They are as follows: (1) each four cycles, the slope of the fitting straight lines of north-south asymmetry values changes its sign, and (2) the asymmetry signs of solar activity at both the low (>0 degrees - = 25 degrees - = 10 degrees - <25 degrees). When the former two are the same as the latter, solar activity is asymmetrically distributed in the hemispheres but symmetrically distributed when the former two differ from the latter. Moreover, asymmetry values of solar activity for the whole disk are always located between the first two and the latter and seem to be the averages of the first two and the latter, suggesting that the asymmetry of solar activity may be a function of latitude. In the forthcoming cycle 24, asymmetry of solar activity is inferred as being similar to cycle 12, and solar activity should remain dominant in the southern hemisphere.

Overview of R&D on Plasma-Facing Materials and Components in China

Abstract A project to realize, in several years, a W/Cu divertor on Experimental Advanced Superconducting Tokamak (EAST) with ITER-like plasma-facing component (PFC) configuration was launched at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) in 2010. The ITER-like configuration should withstand the rapid increase in particle and power impact onto the divertor and demonstrate the feasibility of the ITER design under practical long-pulse tokamak plasmas. The project could help not only EAST experiments, but also realize ITER PFC technology validation and bring answers in a timely manner for the ITER full-W divertor for the nuclear phase. Southwest Institute of Physics (SWIP) will have 10% of the first wall (FW) procurement package of the enhanced heat flux (EHF) type. The materials have been developed and characterized according to the ITER-grade material specifications, including vacuum hot pressing (VHP)-Be, CuCrZr alloy, and 316L(N)-IG forged blocks, and qualification testing of the VHP-Be tiles joining to the CuCrZr heat sink by hot isostatic pressing (HIP) has been carried out. Some Chinese universities have started to explore new grades of W materials, e.g., carbide or oxide dispersion strengthened fine grain W materials, and investigated their behavior under high heat loads.

Characteristics of mesospheric gravity waves over the southeastern Tibetan Plateau region

The Tibetan Plateau (TP), known as “Third Pole” of the Earth, has important influences on global climates and local weather. An important objective in present study is to investigate how orographic features of the TP affect the geographical distributions of gravity wave (GW) sources. Three-year OH airglow images (November 2011 to October 2014) from Qujing (25.6°N, 103.7°E) were used to study the characteristics of GWs over the southeastern TP region. Along with the almost concurrent and collocated meteor radar wind measurements and temperature data from SABER/TIMED satellite, the propagation conditions of three types of GWs (freely propagating, ducted, or evanescent) were estimated. Most of GWs exhibited ducted or evanescent characteristics. Almost all GWs propagate southeastward in winter. The GW propagation directions in winter are significantly different from other airglow imager observations at northern middle latitudes. Wind data and convective precipitation fields from the European Centre for Medium-Range Weather Forecasts reanalysis data are used to study the sources of GWs on the edge of the TP. Using backward ray-tracing analysis, we find that most of the mesospheric freely propagating GWs are located in or near the large wind shear intensity region (~10 km–~17 km) on the southeastern edge of the TP in spring and winter. The averaged value of momentum flux is 11.6 ± 5.2 m2/s2 in winter and 7.5 ± 3.1 m2/s2 in summer. This work will provide valuable information for the GW parameterization schemes in general circulation models in TP region.

A statistical analysis of equatorial plasma bubble structures based on an all‐sky airglow imager network in China

This paper investigates the statistical features of equatorial plasma bubbles (EPBs) using airglow images from 2012 to 2014 from a ground-based network of four imagers in the equatorial region of China. It is found that (1) EPBs mainly occur during 21:00–00:00 local time (LT) in equinoxes. There is an asymmetry in occurrence rates between March (June) and September equinoxes (December solstices). (2) Most EPBs occur in groups of two to six depletions. The distance between adjacent EPB depletions is ~100–700 km, and the average is 200–300 km. The zonal extension of an EPB group is usually less than 1500 km but can reach 3000 km. (3) EPBs usually have a maximum drift velocity near 100 m/s at 21:00–22:00 LT in 9.5° ± 1.5° geomagnetic latitude and then decrease to 50–70 m/s toward sunrise. (4) The averaged westward tilt angle of most EPBs (with respect to the geographic north-south) increased from 5°–10° to 23°–30° with LT between 20:00 and 03:00 LT, then decreasing to 10°–20° toward sunrise. (5) When 90   140. The maximum PMLE increases by 3.4°–5.5° when F10.7 changes from 90 to 190. (6) The EPB occurrence patterns and zonal drift velocities are significantly different from those at Kolhapur, India, which locates west to our stations by 20.0°–32.0° in longitude.