Two ultraviolet radiation datasets that cover China

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes

Vector magnetocardiography using compact optically-pumped magnetometers

Optically pumped magnetometers can provide functionality for bio-magnetic field detection and mapping. This has attracted widespread attention from researchers in the biomedical science field. Magnetocardiography has been proven to be an effective method for examining heart disease. Notably, vector magnetocardiography obtains more spatial information than the conventional method by only taking a component that is perpendicular to the chest surface. In this work, a spin-exchange-relaxation-free (SERF) magnetometer with a compact size of 14 mm × 25 mm × 90 mm was developed. The device has a high sensitivity of 25 fT/ Hz. Meanwhile, in the multichannel working mode, synchronous sensor manipulation and data acquisition can be achieved through our control software without additional data acquisition boards. Since a typical SERF magnetometer only responds to dual-axis magnetic fields, two sensors are orthogonally arranged to form a vector detection channel. Our system consists of seven channels and allows 7 × 9 vector MCG mapping by scanning. High-quality heart vector signals are measured, and P peak, QRS peak, and T peak can be distinguished clearly. To better demonstrate the vectorial information, a vector scatter plot form is also provided. Through a basic bio-electric current model, it demonstrates that triaxial MCG measurements capture a richer spatial current information than traditional uniaxial MCG, offering substantial diagnostic potential for heart diseases and shedding more light on the inversion of cardiac issues

Phenology acts as a primary control of urban vegetation cooling and warming: A synthetic analysis of global site observations

International audienc

The Microwave Temperature Vegetation Drought Index (MTVDI) based on AMSR-E brightness temperatures for long-term drought assessment across China (2003–2010)

International audienc

Redistribution characteristics of atmospheric precipitation in different spatial levels of Guangzhou urban typical forests in southern China

The aims of the present study were to determine the pH variation and chemical feature of atmospheric precipitation during the research period. We also investigated the redistribution characteristics of rainfall while passing through the canopy layer, leaf-litter layer and soil layer, successively to quantify the acid rain buffering capacity of these spatial levels in the evergreen broadleaved forest (EBF), deciduous broadleaved forest (DBF) and coniferous forest (CF) in Guangzhou urban area, China. Results showed that the rainfall was typically acidic, and the acid rain type in Guangzhou urban area is converted from sulfuric acid type to mixed type of sulfuric acid and nitric acid. The major ions from the canopy to the forest floor differed within the three forest types. However, the enrichment phenomenon of base cations in soil leachate in EBF and DBF implied that nutrient loss was more serious in the broadleaved forest than in the coniferous forest. Variability of ionic concentration and pH in the vertical sequence of different tree species showed that the net ion concentration variation index has a significant conic relationship with ne pH change rate. We also built an acid rain buffering index, which combines the neutralization and interception effects of vegetation to acid rainfall. The present results indicated that the three forest types in urban Guangzhou all have certain buffering capacity to acid rain, and following the order: DBF > EBF > CF. In the meanwhile, the forest canopy is the biggest acid rain buffer in urban Guangzhou, following by the soil

Quantifying the biophysical effects of forests on local air temperature using a novel three-layered land surface energy balance model

International audienceThe well-documented energy balance dynamics within forest ecosystems are poorly implemented in studies of the biophysical effects of forests. This results in limitations to the accurate quantification of forest cooling/ warming on local air temperature. Taking into consideration the forest air space, this study proposes a three-layered (canopy, forest air space and soil [CAS]) land surface energy balance model to simulate air temperature within forest spaces (T af) and subsequently to evaluate its biophysical effects on forest cooling/warming, i.e., the air temperature gradient (ΔT a) between the T af and air temperature of open spaces (T ao) (ΔT a = T af − T ao). We test the model using field data for 23 sites across 10 cities worldwide; the model shows satisfactory performance with the test data. High-latitude forests show greater seasonal dynamics of ΔT a , generating considerable cooling of local air temperatures in warm seasons but minimal cooling or even warming effects during cool seasons, while low-latitude tropical forests always exert cooling effects with less interannual variability. The interannual dynamics of ΔT a are significantly related to the seasonality of solar geometry and canopy leaf phenology. The differences between forest canopy temperature (T c) and T ao , which are the two most important terms attributed by the CAS model in impacting T af , explain a large part of forest cooling and warming (May-July: R 2 = 0.35; November-January: R 2 = 0.51). The novel CAS model provides a feasible way to represent the energy balance within forest ecosystems and to assess its impacts on local air temperatures globally