平流层臭氧和辐射场的季节分布特征

Seasonal Distribution of Ozone and Radiation Field at the Stratosphere

利用美国NCAR化学气候耦合模式WACCM3对平流层温度场、风场、臭氧及辐射场进行了模拟.结果表明,在适宜飞艇长期驻留的准零风层高度20~22 km(对应大气压强范围为50~30 hPa,以下均采用气压值表征对应大气高度),7—8月风速小于5m·s^(-1)的风带可长期稳定在40°N以北.臭氧空间分布显示,在30hPa气压高度处中国地区臭氧浓度出现了带状分布,30 hPa高度以下低纬度地区臭氧浓度低于中纬度地区.平流层太阳加热率的时空变化表明,在平流层上层,太阳加热率可达100×10^(-6)K·s^(-1),而在平流层下层,只有10×10^(-6)K·s^(-1).6—8月中国区域的太阳加热率大于9月;在100~30 hPa高度内,中纬度地区太阳加热率高于低纬度地区,在30 hPa高度以上,低纬度地区太阳加热率高于中纬度地区;8—9月30~40 hPa高度处,太阳加热率的空间变化较小.在30 hPa高度上,太阳加热率在40°N昼夜变化最大;50 hPa高度处,太阳加热率的昼夜变化小于30 hPa高度处,而且白天太阳加热率出现极大值的纬度明显靠北.平流层低纬度地区的长波加热率小于中纬度地区.青藏高原由于地形特殊,其6—7月的臭氧浓度、太阳加热率和长波加热率均小于同纬度其他地区.

The coupled chemistry-climate model WACCM3(Whole Atmosphere Community Climate Model) developed by NCAR is applied to study the seasonal variations of the stratospheric temperature,wind,ozone and radiation fields.The stratospheric quasi-zero wind layer at around20~22 km(i.e.,atmosphere pressure range is 50~30 hPa),where the wind speed is less than 5 m·s^(-1)and is stable to the north of 40°N during July and August,is suitable for long-term stay of airships.There appears a belt of ozone at 30 hPa over China and ozone concentrations are greater in the midlatitudes than in the lower latitudes below 30 hPa.There are significant seasonal spatial variations in solar heating rates in the stratosphere.In the upper stratosphere,the maximum solar heating rate reaches 100×10^(-6)K·s^(-1)while in the lower stratosphere the maximum solar heating rate is only10×10^(-6)K·s^(-1).The solar heating rate is greater in June to August than in September over China.The solar heating rate is greater in the mid-latitudes than in the lower latitudes between 100 hPa and 30 hPa and is greater in the lower latitudes than in the mid-latitudes above 30 hPa.The change of solar heating rate is small in August and September at 30 hPa and 40 hPa.The maximum diurnal variation of solar heating rate appears at 40°N at 30 hPa.At 50 hPa,the diurnal variation of solar heating rate is smaller than that at 40 hPa and the maximum variation occurs farther south.The longwave heating rate is smaller in the lower latitudes than in the mid-latitude stratosphere.In particular condition of terrain,the ozone concentration,solar heating rate and longwave heating rate are smaller over Tibetan Plateau than other areas at the same latitude.