This paper describes the methodology of an ongoing project of constructing an East Asian climate database REACHES based on Chinese historical documents. The record source is Compendium of Meteorological Records of China in the Last 3000 Years which collects meteorology and climate related records from mainly official and local chronicles along with a small number of other documents. We report the digitization of the records covering the period 1644–1795. An example of the original records is translated to illustrate the typical contents which contain time, location and type of events. Chinese historical times and location names are converted into Gregorian calendar and latitudes and longitudes. A hierarchical database system is developed that consists of the hierarchies of domains, main categories, subcategories, and further details. Historical events are then digitized and categorized into such a system. Code systems are developed at all levels such that the original descriptive entries are converted into digitized records suitable for treatment by computers. Statistics and characteristics of the digitized records in the database are described.

Rainfall erosivity (or water erosion) has severe implications on agriculture, water, and land use management. Though, there were Rainfall erosivity studies on regional and global scale, tropical cyclones’ Rainfall erosivity is poorly assessed and have not been documented for one of the most cyclones affecting regions of the world like Taiwan. Here, using 15-years of raindrop size distributions (RSD) and 60-years of hourly rain gauges data, we estimated cyclones (also called typhoons) rainfall erosivity over Taiwan, and establish that typhoons’ mean rainfall erosivity is higher than the global mean rainfall erosivity. Moreover, regional variability of typhoons rainfall erosivity showed an increasing pattern from north to south (Taipei to Pingtung), with relatively higher values over eastern and southern parts of Taiwan. The annual mean erosivity of typhoons rainfall showed raising trends over eastern and southern Taiwan during 1958–2017. Our results provide an insight in assessing the land use and agricultural management for Taiwan.

Determination of the physical mechanisms of energy transfer of tropospheric disturbances to the ionosphere is one of the fundamental problems of atmospheric physics. This article presents the results of observations carried out using two-wavelength lidar sensing at tropospheric altitudes and satellite GPS measurements during a meteorological storm in Kaliningrad (Russia, 54.7° N, 20.5° E) on 1 April 2016. During lidar sensing, it was found that the amplitudes of variations in atmospheric parameters with periods of acoustic (AWs) and internal gravity (IGWs) waves significantly increased. As a result of numerical modeling using the AtmoSym software package, it was shown that there is a noticeable increase in the period of temperature disturbances from 6–12 min to 10–17 min at altitudes from 150 km up to 230 km during the vertical propagation of acoustic waves and internal gravity waves from the troposphere. Nonlinear and dissipative processes in this layer lead to the formation of sources of secondary waves in the thermosphere with periods longer than those of primary ones. In this case, the unsteady nature of the wave source and the short duration of its operation does not lead to significant heating of the thermosphere. Simultaneous satellite observations demonstrate the response of the ionosphere (total electron content (TEC) disturbance) to tropospheric disturbances. Analysis of the time series of the amplitudes of the reflected lidar signal and TEC made it possible to determine that the response time of the ionosphere to tropospheric disturbances is 30–40 min.

Understanding of the flow field and falling patterns of ice crystals is fundamental to cloud physics and radiative transfer, and yet the complex shape hampers a comprehensive understanding. In order to create better understanding of falling patterns of columnar crystals, this study utilizes a computational fluid dynamics package and explicitly simulates the motion as well as the flow fields. Three modes of patterns (i.e., strong damping, fluttering, and unstable modes) were identified in the space of inverse aspect ratio (q) and Reynolds number (Re). The boundary of stability depicts the “L” shape as found in a previous experimental study. This study newly found that the range of Re for stable motion increases with a decrease in q. Decomposition of hydrodynamic torques indicates that, for stable mode, the pressure and viscous torques acting on the lower prism faces counteract the rotation when the inclination angle becomes 0°. The unstable motion was attributed to the pressure torque acting on the upper prism faces, which is associated with eddies that lag behind the oscillating boundary. Observed Re–q relationships of columns suggest that the strong damping mode is most likely to occur in the atmosphere, but the fluttering mode is also possible. Furthermore, the time scales of oscillation and damping were parameterized as a function of q and Re. The impact of the fluttering on the riming process is limited at the beginning, which supports the current formulation in numerical weather and climate models.

This study presents a new epistemological analysis of drought chronology through a well-defined methodology for reconstructing past drought series, as well as series of other associated ecological and societal impact variables. Instead of building a grading system based on mixed criteria, this method facilitates transparency in the reconstruction process and enables the statistical examination of all variables when building series. The data for the present study are derived mainly from the REACHES (Reconstructed East Asian Climate Historical Encoded Series) database; however, other archival documentary and index data from independent sources are also applied to understand drought narratives and to cross-check and validate the analysis derived from REACHES. From the time series analysis, six severe drought periods are identified in the Qing dynasty, and then a spatial analysis is performed to demonstrate the spatial distribution of drought and other variables in the six periods, as well as a social network analysis to reveal connections between drought and other ecological and societal variables. Research results clearly illustrate the role of human intervention in influencing the impacts of drought and their societal consequences. Particularly, the correlation between drought and socioeconomic turmoil is not strong; crop failure and famine are important intermediate factors, while ecological factors such as locust and disaster relief measures are all imperative to intervene between crop production and famine. Implications of the study on drought impact are provided, as well as the significance of drought on historical climate reconstruction studies.

The fall attitudes and the flow fields of falling hexagonal ice plates are studied by numerically solving the transient incompressible Navier–Stokes equation for flow past ice plates and the body dynamics equations representing the 6-degrees-of-freedom motion that determine the position and orientation of the ice plates in response to the hydrodynamic force of the flow fields. The ice plates investigated are from 1 to 10 mm in diameter, and the corresponding Reynolds number ranges from 46 to 974. The results indicate that the 1-mm plate generates a steady flow field and exhibits a steady motion, whereas the rest of the ice plates generate unsteady flow fields and exhibit unsteady motions, including horizontal translation, rotation, and axial oscillation. The horizontal translation is primarily determined by the inclination due to oscillation. The pressure distributions around the falling plates are examined and discussed in association with the oscillation. The vortex structure in the wake of the plate is examined. Empirical formulas for fall speed, oscillation frequency, and drag coefficient are given. Potential impacts of the fall attitudes and flow characteristics on the microphysics of ice plates are discussed.