Dynamic Simulation of Soil Moisture Changes of Peanut Root Zone in Low-Hilly Red Soil Areas Based on SiB2 and Data Assimilation

ZHANG Qian;JING Yuan-shu;Collaborative Innovation Center of Meteorological Disaster Forecasting Warning and Assessment/Key Laboratory of Agricultural Meteorology in Jiangsu;Department of Oncology,College of Applied Meteorology,Nanjing University of Information Science&Technology;

SiB2;;low-hilly red soil area;;soil moisture dynamic changes;;Ensemble Kalman Filter;;data assimilation

SiB2( Simple Biosphere Model version 2) is a land surface process model which combines plant physiology and soil micrometeorology to study the water,energy and CO_2 flux variation in single-layer vegetation. In order to make the SiB2 suitable for the small watershed ecosystem of farmland in low-hilly red soil areas in Jiangxi province,according to the measurements of experimental site in peanut fields in Yujiang and the classifications of soil and crop from SiB2,in this paper,the soil characteristic parameters and peanuts morphology parameters were confirmed,some peanuts physiological and optical parameters were adjusted and the calculations of long-wave radiation in SiB2 were modified. On this basis,the nearly strata observation data in seedling,flowering and plump-eared three key growing stages of peanut were selected and inputted into the model to acquire short-term simulation about the dynamic changes of soil moisture in peanut root field,the influences of the characteristics of peanut in different growing stages and meteorological factors on the simulation results were explored,and a single-point scheme of data assimilation based on Ensemble Kalman Filteron was proposed to improve precision. The results of validation with the observation data shows that: in different growing periods,the less extreme the weathers,the more stable the biological form of the peanut plants and the more accurately the simulation results. After the data assimilation,the precision of the model is improved obviously.