ALBERT

Description: Ionospheric responses to sudden stratospheric warming (SSW) are not well understood, particularly in the mid-latitudes and under high solar conditions. During the 2013 SSW, ionospheric disturbances were observed in eight locations on the meridional chain from 30.5°N to 42.8°N in northern China. The mid-latitude ionosphere responded strongly to the SSW despite being under high solar flux. The F2-layer maximum electric density increased by more than 80%, and the peak height was elevated more than 60 km. Well-set and organized semidiurnal variations were recorded in early and middle January during the SSW in eight observation locations. The expected f o F 2 decrease in the afternoon hours was not clearly discernible; however, nighttime enhancements occurred frequently. The time-period spectra of the average f o F 2 and zonal winds and meridional winds at altitudes of 86-95 km presented quasi-16-day planetary wave-like oscillations during the warming event. The coupling between the atmosphere and ionosphere may be strengthened by the quasi-16-day waves. The amplified diurnal, semidiurnal and ter-diurnal tides in f o F 2 were also recorded during the warming, in good agreement with earlier observations. Importantly, the variations in the semidiurnal tides included a 16-day periodic component, indicating that the modulated semidiurnal tides may transmit this 16-day planetary wave-like oscillations to the F-region through wind dynamo. Although the PW-tide interaction theory is not novel, it is of significance in the mid-latitude ionospheric response to SSW.

Description: Interactions between lakes and the atmosphere at high-altitudes are still poorly understood due to difficulty in accessibility of direct measurements. This is particularly true for the Qinghai–Tibet Plateau (QTP), where approximately 50% of the lakes in China are located. Continuous direct measurements of the water flux and surface energy budget were made over the largest high-altitude saline lake in China, Qinghai Lake on the northeastern QTP, using the eddy covariance (EC) method from 11 May, 2013 through 10 May, 2015. Results indicated that annual evaporation of Qinghai Lake was 832.5 mm for 2013/2014 and 823.6 mm for 2014/2015, respectively. The surface energy budget and evaporation showed a strong seasonal pattern, with peaks in the latent and sensible heat flux observed in autumn and early winter. There was a 2–3 month delay between the maximum net radiation and maximum latent and sensible heat fluxes. Intraseasonal and seasonal variations in latent and sensible heat flux were strongly affected by different air masses. Westerly cold and dry air masses increased evaporation while southeast moist air mass suppressed evaporation, suggesting that the lakes might serve as an 'air-conditioner' to modify the temporal heat and water flux in the QTP.

Description: The solar eclipse effects on the ionosphere are very complex. Except for the ionization decay due to the decrease of the photo-chemical process, the couplings of matter and energy between the ionosphere and the regions above and below will introduce much more disturbances. Five ionosondes in the Northeast Asia were used to record the midlatitude ionospheric responses to the solar eclipse of 20 May 2012. The latitude dependence of the eclipse lag was studied firstly. The fo F2 response to the eclipse became slower with increased latitude. The response of the ionosphere at the different latitudes with the same eclipse obscuration differed from each other greatly. The plasma flux from the protonsphere was possibly produced by the rapid temperature drop in the lunar shadow to make up the ionization loss. The greater downward plasma flux was generated at higher latitude with larger dip angle and delayed the ionospheric response later. The waves in the fo Es and the plasma frequency at the fixed height in the F-layer are studied by the time-period analytic method. The gravity waves of 43-51min center period during and after the solar eclipse were found over Jeju and I-Cheon. The northward group velocity component of the gravity waves was estimated as ~108.7m/s. The vertical group velocities between 100- 150km height over the two stations were calculated as ~5 and ~4.3m/s upwards respectively, indicating the eclipse induced gravity waves propagated from below the ionosphere.

Description: In the present study, the occurrence and characteristics of equatorial plasma bubble (EPB) has been analyzed using the GPS data from continuously operating reference stations (CORS) network over Hong Kong during 2001-2012. The analysis found maximum EPB occurrences during the equinoctial months and minimum EPB occurrences during the December solstice throughout 2001-2012 except during the solar minimum in 2007-2009. The maximum EPB occurrences were observed in June solstice during 2007-2008, whereas for 2009, EPB occurrences were quite higher for June solstice but slightly smaller than the March equinox. Generally, EPB occurrences are found to be more prominent during nighttime hours (19:00-24:00 hours) than daytime hours. The day and nighttime EPB occurrences were inferred and found to vary linearly with solar activity and have an annual correlation coefficient (R) of ~ 0.92 with F 10.7 cm solar Flux and ~0.88 with sunspot number. Moreover, the impact of solar activity on EPB occurrences is found to be dependent on seasons with maximum during the equinox (R = 0.80) and minimum during the summer season (R = 0.68). The detail study of EPB occurrences during 2 typical cases of geomagnetic storms on 6 November and 24 November 2001 found that the storm on 24 November triggered the EPB occurrence whereas storm on 06 November suppressed the EPB occurrence. The enhancement/suppression of EPB occurrences during storms periods is a consequence of a storm induced prompt penetration electric field (PPE) as well as disturbance dynamo electric field (DDE) effects associated with the main phase of the geomagnetic storm.

Description: Hainan coherent scatter phased array radar (HCOPAR) located at low-latitude of China has recorded the extremely rare daytime F -region irregularities at noon of 22 July 2013 and 23 May 2016. The two field-aligned irregularities (FAIs) appeared in the topside F2 -layer and presented small Doppler velocities and narrow spectral widths. The fan sector maps show that the FAIs moved northward with almost no zonal speed. The irregularities emerged in the geomagnetically quiet condition and were irrelevant to the storm induced eastward electric field as other daytime cases. More than two hours after the emergency of the daytime irregularities over Hainan, the Shaoyang digisonde situated ~870 km north to the HCOPAR recorded the spread- F in ionospheric F1 -layer. According to the echo altitudes, the spread- F may connect the daytime bubbles via magnetic field line. The strong photo-ionization after sunrise made it difficult to generate the plasma bubbles in the sunlit ionosphere. Consequently, the two midday FAIs over Hainan may drift along the magnetic field lines from higher altitudes in the south and are most likely the remnant of previous night's bubbles.

Description: Rainfall interception loss plays an important role in eco-hydrological processes in dryland shrub ecosystems, but its drivers still remain poorly understood. In this study, a statistical model was developed to simulate interception loss based on the mass balance measurements arising from the partitioning of rainfall in two dominant xerophytic shrub ( Hippophae rhamnoides and Spiraea pubescens ) communities in the Loess Plateau. We measured throughfall and stemflow in the field under natural rainfall, calculated the canopy storage capacity in the laboratory, and identified key factors controlling these components for the two shrubs. We quantified and scaled-up the stemflow and the canopy storage capacity measurements from the branches and/or leaves to stand level. The average interception loss, throughfall, and stemflow fluxes account for 24.9%, 72.2%, and 2.9% of the gross rainfall for H. rhamnoides , and 19.2%, 70.7%, and 10.1% for S. pubescens , respectively. Throughfall increased with increasing rainfall for both shrubs, however, it was only correlated with the leaf area index (LAI) for S. pubescens . For stemflow measured from individual branches, we found that the rainfall amount and basal diameter are the best predictors for H. rhamnoides , while rainfall amount and branch biomass appear to be the best predictors for S. pubescens . At the stand level, stemflow production is affected by the rainfall amount for H. rhamnoides , and it is affected by both the rainfall amount and the LAI for S. pubescens . The canopy storage capacity of H. rhamnoides (1.07–1.28 mm) was larger than S. pubescens (0.88–1.07 mm), and it is mainly determined by the branches and stems of H. rhamnoides , and the leaves of S. pubescens . The differences in interception loss between the two shrub stands are mainly attributed to different canopy structures induced differences in stemflow production and canopy storage. We evaluated the effects of canopy structure on rainfall interception loss, and our developed model provides a better understanding of the effects of the canopy structure on the water cycles in dryland shrub ecosystems.

Description: The dense observation points of the oblique-incidence ionosonde network in North China make it possible to discover the ionospheric regional variations with relatively high spatial resolution. The ionosonde network and the Beijing digisonde are used to investigate the ionospheric nighttime oscillations in January and February 2011. The electron density enhancements occurring before and after midnight present the obvious opposite latitudinal dependence in the time-latitude maps, which are composed by the differential critical frequency of F2 -layer. The pre-midnight enhancements (PRMEs) appeared earlier in the north and then moved to south. The post-midnight enhancements (POMEs) did the opposite. The data analysis shows that the PRME was a part of the large-scale travelling ionospheric disturbance (LSTID), which may be produced by gravity waves. The southward propagation of the LSTIDs is considered to form the positive latitudinal dependence of the wave peaks and troughs. The post-midnight F -layer oscillation was composed by a single enhancement and a single decline following it. The westward electric field induced E×B drift, which pushed the F -layer to lower altitudes with higher recombination loss, was most likely to compress the plasma and produce the POMEs. Along with the continuously dropping of the layer, the recombination loss exceeded the density increase due to the compression effect and then the electron density decline appeared.

Description: To improve the temperature characteristics and catalytic efficiency of a glycoside hydrolase family (GHF) 11 xylanase from Aspergillus oryzae (AoXyn11A), its variants were predicted based on in silico design. Fir...

Description: Valproic acid (VPA), with inhibition activity mainly towards histone deacetylase (HDAC) and Glycogen Synthase Kinase (GSK)-3, and lithium, with inhibition activity mainly toward GSK-3, are both prescribed in clinical as mood-stabilizers and anticonvulsants for the control of bipolar disorder. This study aims to compare the immuno-modulation activities of VPA and lithium, especially on the differentiation and functions of dendritic cells (DC). Our data show that treatment with VPA or lithium effectively alleviated the severity of collagen-induced arthritis triggered by LPS in mice. Both agents reduced the serum level of IL-6 and IL-10 after LPS challenge in mice. VPA and lithium both induce significant down-regulation of group I CD1 expression and secretion of IL-6 during differentiation of human monocyte-derived immature DC, while they differ in the induction of CD83 and CD86 expression, secretion of IL-8, IL-10, and TNF-α. Upon stimulation of immature DC with LPS, VPA and lithium both reduced the secretion of IL-6 and TNF-α. However, only lithium significantly increased the production of IL-10, while VPA increased the production of IL-8 but substantially reduce the secretion of IL-10 and IL-23. Treatment with VPA resulted in a reduced capacity of LPS-stimulated DC to promote the differentiation of T helper 17 cells that are critical in the promotion of inflammatory responses. Taken together, our results suggest that VPA and lithium may differentially modulate inflammation through regulating the capacity of DC to mediate distinct T cell responses, and they may provide a complementary immunomodulatory effects for the treatment of inflammation-related diseases. This article is protected by copyright. All rights reserved