Dynamic changes in moisture content and applicability analysis of a typical litter prediction model in Yunnan Province

Background Forest fire risk predictions are based on the most conservation daily predictions, and the lowest litter moisture content of each day is often used to predict the day’s fire risk. Yunnan Province is the area with the most frequent and serious forest fires in China, but there is almost no research on the dynamic changes and model predictions of the litter moisture content in this area. Therefore, to reduce the occurrence of forest fires and improve the accuracy of forest fire risk predictions, it is necessary to understand these dynamic changes and establish an appropriate prediction model for the typical litter moisture content in Yunnan Province. Method During the fire prevention period, daily dynamic changes in the litter moisture content are obtained by monitoring the daily step size, and the relationships between the litter moisture content and meteorological elements are analyzed. In this study, the meteorological element regression method, moisture code method and direction estimation method are selected to establish litter moisture content prediction models, and the applicability of each model is analyzed. Results We found that dynamic changes in the litter moisture content have obvious lags compared with meteorological elements, and the litter moisture content is mainly related to the air temperature, relative humidity and wind speed. With an increase in the sampling interval of meteorological elements, the significances of these correlations first increase and then decrease. The moisture content value obtained by directly using the moisture code method in the Fire Weather Index (FWI) significantly different from the measured value, so this method is not applicable. The mean absolute error (MAE) and mean relative error (MRE) values obtained with the meteorological element regression method are 2.97% and 14.06%, those from the moisture code method are 3.27% and 14.07%, and those from the direct estimation method are 2.82% and 12.76%, respectively. Conclusions The direct estimation method has the lowest error and the strongest extrapolation ability; this method can meet the needs of daily fire forecasting. Therefore, it is feasible to use the direct estimation method to predict litter moisture contents in Yunnan Province.

Design of Meteorological Element Detection Platform for Atmospheric Boundary Layer Based on UAV

Among current detection methods of the atmospheric boundary layer, sounding balloon has disadvantages such as low recovery and low reuse rate, anemometer tower has disadvantages such as fixed location and high cost, and remote sensing detection has disadvantages such as low data accuracy. In this paper, a meteorological element sensor was carried on a six-rotor UAV platform to achieve detection of meteorological elements of the atmospheric boundary layer, and the influence of different installation positions of the meteorological element sensor on the detection accuracy of the meteorological element sensor was analyzed through many experiments. Firstly, a six-rotor UAV platform was built through mechanical structure design and control system design. Secondly, data such as temperature, relative humidity, pressure, elevation, and latitude and longitude were collected by designing a meteorological element detection system. Thirdly, data management of the collected data was conducted, including local storage and real-time display on ground host computer. Finally, combined with the comprehensive analysis of the data of automatic weather station, the validity of the data was verified. This six-rotor UAV platform carrying a meteorological element sensor can effectively realize the direct measurement of the atmospheric boundary layer and in some cases can make up for the deficiency of sounding balloon, anemometer tower, and remote sensing detection.

The Land’s Susceptibility, Due to Atmospheric Precipitations, Within the Catchment Area of Câlnău

The climatic factors, generally, and the precipitation amounts recorded, especially, constitute some of the factors which condition the development and intensity of actual geomorphologic processes. One of the most employed climatic parameters for determining the land’s susceptibility to atmospheric precipitations, with real and concrete applications into the dynamic geomorphology, is the Angot factor. The precipitations represent a crucial meteorological element in initiating, sustaining and reactivating some geomorphologic processes, acting as a modelling agent for every type of landscape. This influence can be highlighted by quantifying the values of some characteristic variables (length, frequency and intensity), as well as temporally confining individual and successive sequences, which present a certain degree of susceptibility. The general objective of this research, through the analysis of precipitations and the Angot parameter, is to identify, on one hand, the months, seasons or years with a very high or very low susceptibility to the occurrence of bank erosion phenomena, and on the other, to examine the value variations of this parameter across the year. The purpose is to recognize a cumulative of pluviometric conditions which could contribute to inducing, in general, the modelling processes. The study of land’s susceptibility to atmospheric precipitations was conducted within the morpho-hydrographic drainage system of Câlnău.

Research on the Indoor and Outdoor Wind Environment of University Apartment in the Hot in Summer and Cold in Winter Area

Wuhan,which is hot in summer and cold in winner climatic region,lies in the east of Jianghan Plain.High temperature and high humidity is characteristics of the city.Thus,it’s vital to strength the natural ventilation of building.Simulation for the situation of wind in Wuhan a certain university in this paper,which take average meteorological element for many years in Wuhan to be initial condition.Selecting Fluent Airpak to conduct flow field Simulation Analysis in the process of calculation.posing problem which exist natural ventilation design universally,according to experimental data,and give tactics to solve it,aiming at utilizing natural wind more effectively and more rationally,and creating comfortable indoor and outdoor thermal environment.