A two-dimensional, non-reactive convective cloud transport model is used to simulate in detail the vertical transport and wet scavenging of soluble pollutant gases by a deep thunderstorm systems Simulations show that ...A two-dimensional, non-reactive convective cloud transport model is used to simulate in detail the vertical transport and wet scavenging of soluble pollutant gases by a deep thunderstorm systems Simulations show that for gases with not very high solubility, a deep and intense thunderstorm can still rapidly and efficiently transport them from boundary layer(PBL) up to mid and upper troposphere. resulting in a local significant increase of concentration in the upper layer and a reduction in PBL. Dissolution effects decrease both the incloud gas concentration and the upward net fluxes. The higher the solubility is, the more remarkable the decrease is. However, for very low soluble gases (H<102 Matm-1), the influences are very slight. In addition, the effects of irreversible dissolution and aqueous reactions in drops on the vertical transport of gaseous pollutants are estimated in extreme.展开更多
The vertical transport features of gaseous pollutants, with a negative exponent profile of concentration, by different types of convective cloud systems are numerically investigated by using a two-dimensional, reactlo...The vertical transport features of gaseous pollutants, with a negative exponent profile of concentration, by different types of convective cloud systems are numerically investigated by using a two-dimensional, reactlonless convective cloud transport model. The results show that an isolated, weak storm is able to pump pollutant gas out PBL and transport it to the mid-troposphere, whereas a deep. intense thunderstorm can very efficiently transport air pollutants up to the mid and upper troposphere and laterally spread with anvil, forming an extensive concentration surge layer at aliitnde of ten odd kilometers altitude. Each type of convective transport results in concentration reduction in PHL. In a wind shear environment the transport efficiency of deep thunderstorm significantly increases and the pollutants enter into clouds on the downshear side at low level and spread downwind in anvil layer. On the other hand, for a cumulus cloud with plenty of liquid water. the gas dissolution effect is increased, and the irreversible aqueous reactions, in extreme, may significantly weaken the vertical transports of pollutant gases even with solubility coefficients no more than 103 M atm-1.展开更多
The upward lightning(UL) initiated from the top of tall buildings(at least above 100 m) is a type of atmospheric discharge. Currently, we understand the nature of the UL from ground observations, but the corresponding...The upward lightning(UL) initiated from the top of tall buildings(at least above 100 m) is a type of atmospheric discharge. Currently, we understand the nature of the UL from ground observations, but the corresponding theoretical research is lacking. Based on an existing bidirectional leader stochastic model, a stochastic parameterization scheme for the UL has been built and embedded in an existing two-dimensional thundercloud charge/discharge model. The ULs simulated from the experiments with two-dimensional high resolution agree generally with the observation results. By analyzing the charge structure of thunderstorm clouds, we determined the in-cloud environmental characteristics that favor the initiation of conventional cloud-to-ground(CG) flashes and analyzed the differences and similarities of some characteristics of the positive and the negative UL. Simulation results indicate that the positive ULs are typically other-lightning-triggered ULs(OLTUL) and are usually a discharge phenomenon between the ground and the lower positive charge region appearing below the main middle negative charge region. The effect of the previous in-cloud lightning(IC) process of space electrical field provides favorable conditions for the initiation of a positive UL. Its entire discharge process is limited, and the branches of the leader are fewer in number as its discharge is not sufficient. A negative UL is generally a discharge phenomenon of the dipole charge structure between the ground and the main negative charge region. The lower temperature stratification and the sinking of the hydrometeors typically initiate a negative UL. Negative ULs develop strongly and have more branches. The OLTUL is initiated mainly during the development stage of a thunderstorm, while the self-triggered UL(STUL) is initiated mainly during the dissipation stage of a thunderstorm.展开更多
文摘A two-dimensional, non-reactive convective cloud transport model is used to simulate in detail the vertical transport and wet scavenging of soluble pollutant gases by a deep thunderstorm systems Simulations show that for gases with not very high solubility, a deep and intense thunderstorm can still rapidly and efficiently transport them from boundary layer(PBL) up to mid and upper troposphere. resulting in a local significant increase of concentration in the upper layer and a reduction in PBL. Dissolution effects decrease both the incloud gas concentration and the upward net fluxes. The higher the solubility is, the more remarkable the decrease is. However, for very low soluble gases (H<102 Matm-1), the influences are very slight. In addition, the effects of irreversible dissolution and aqueous reactions in drops on the vertical transport of gaseous pollutants are estimated in extreme.
文摘The vertical transport features of gaseous pollutants, with a negative exponent profile of concentration, by different types of convective cloud systems are numerically investigated by using a two-dimensional, reactlonless convective cloud transport model. The results show that an isolated, weak storm is able to pump pollutant gas out PBL and transport it to the mid-troposphere, whereas a deep. intense thunderstorm can very efficiently transport air pollutants up to the mid and upper troposphere and laterally spread with anvil, forming an extensive concentration surge layer at aliitnde of ten odd kilometers altitude. Each type of convective transport results in concentration reduction in PHL. In a wind shear environment the transport efficiency of deep thunderstorm significantly increases and the pollutants enter into clouds on the downshear side at low level and spread downwind in anvil layer. On the other hand, for a cumulus cloud with plenty of liquid water. the gas dissolution effect is increased, and the irreversible aqueous reactions, in extreme, may significantly weaken the vertical transports of pollutant gases even with solubility coefficients no more than 103 M atm-1.
基金supported by the National Key Basic Research Development Program of China (Grant No. 2014CB441403)the National Natural Science Foundation of China (Grant Nos. 41175003 & 41475003)
文摘The upward lightning(UL) initiated from the top of tall buildings(at least above 100 m) is a type of atmospheric discharge. Currently, we understand the nature of the UL from ground observations, but the corresponding theoretical research is lacking. Based on an existing bidirectional leader stochastic model, a stochastic parameterization scheme for the UL has been built and embedded in an existing two-dimensional thundercloud charge/discharge model. The ULs simulated from the experiments with two-dimensional high resolution agree generally with the observation results. By analyzing the charge structure of thunderstorm clouds, we determined the in-cloud environmental characteristics that favor the initiation of conventional cloud-to-ground(CG) flashes and analyzed the differences and similarities of some characteristics of the positive and the negative UL. Simulation results indicate that the positive ULs are typically other-lightning-triggered ULs(OLTUL) and are usually a discharge phenomenon between the ground and the lower positive charge region appearing below the main middle negative charge region. The effect of the previous in-cloud lightning(IC) process of space electrical field provides favorable conditions for the initiation of a positive UL. Its entire discharge process is limited, and the branches of the leader are fewer in number as its discharge is not sufficient. A negative UL is generally a discharge phenomenon of the dipole charge structure between the ground and the main negative charge region. The lower temperature stratification and the sinking of the hydrometeors typically initiate a negative UL. Negative ULs develop strongly and have more branches. The OLTUL is initiated mainly during the development stage of a thunderstorm, while the self-triggered UL(STUL) is initiated mainly during the dissipation stage of a thunderstorm.
