Characteristics And Non-stomatal Resistance Modeling Of Ozone Dry Deposition On Winter Wheat Under Various Moisture Conditions

In recent years,the increasing ozone concentration is a threat to people’s production and living,tropospheric ozone removed mainly by chemical damage and dry deposition from atmosphere to the surface of the earth.Based on the natural field observation exploring ozone deposition process on winter wheat and how the environmental factors influence,we particularly discusses how the increase of relative humidity,surface humidity and canopy wetness effect the ozone dry deposition on wheat canopy in this paper,we also revised the cuticle resistance,soil resistance and in-canopy aerodynamic resistance function,which improves the ozone dry deposition mechanism,establish a suitable non-stomatal resistance model for this area under dry and wet canopy.The conclusions are as follows:(1)The mean value of the ozone dry deposition flux is-199.11ng·m-2·s-1(negative sign indicates that the precipitation direction is down to the ground).The mean velocity of ozone dry deposition is 0.59m.s-1.The average diurnal cycle of ozone dry deposition flux variation on Wheat canopy and bare land surface are both strong in daytime but weak at night,all day dry deposition on bare land is weaker than wheat canopy,and as a result of non-vegetation over a bare soil,the ozone deposition fluxes were significantly influenced by environmental factors.There are distinguish a single peak distribution among the aerodynamic resistance,quasilaminar resistance,canopy resistance during observation.Aerodynamic resistance mean value is 70.00s·m-1,the quasilaminar resistance mean value is 29.44s·m-1,canopy resistance mean value is 269.77s·m-1.(2)Canopy resistance to ozone dry deposition on winter wheat is influenced by canopy structure,friction velocity,relative humidity,canopy wetness,temperature and solar radiation,etc.Canopy resistance decreases with the increase of the friction velocity,temperature,and solar radiation.And increases with the increase of air relative humidity,but opposite at night.The boundary between dry and wet when air humidity is about 70%.Canopy resistance in atmospheric changes little with the increase of relative humidity when relative humidity less than 70%,and after 70%begin to increase significantly.The increased canopy wetness inhibits the canopy deposition resistance of ozone on winter wheat,relative humidity affect the uptake of stomatal ozone more remarkable than the non-stomatal.(3)In order to refine the resistance of ozone deposition,a suitable non-stomatal resistance model is introduced.Some suitable functions including cuticle resistance,soil resistance and in-canopy aerodynamic resistance applied to the local meteorological conditions and underlying surface vegetation types is revised,so that establish the model of non-stomatal resistance.And we also compared and verified the simulation results of model validation.