Measurements and modelling of I 2 , IO, OIO, BrO and NO 3 in the mid-latitude marine boundary layer
Measurements and modelling of I 2 , IO, OIO, BrO and NO 3 in the mid-latitude marine boundary layer
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DOI：
10.5194/acp-6-1513-2006
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发表时间：
2005-10
影响因子：
6.3
通讯作者：
A. Saiz-Lopez;J. Shillito;H. Coe;J. Plane
中科院分区：
文献类型：
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作者：
A. Saiz-Lopez;J. Shillito;H. Coe;J. Plane
本文报道了中纬度沿海海洋边界层（MBL）中分子碘（I2）、氧化碘（IO，OIO）、氧化溴（BrO）和硝酸根（NO3）的时间序列观测结果。在爱尔兰西海岸的梅斯黑德进行的夏季活动中，使用了一种新的长路径DOAS仪器进行了测量。用B 3 5（0 +）× 1 6 +电子跃迁在535 ~ 575 nm之间检测I2。发现I2混合比从低于检测限（5 ppt）到夜间最大值93 ppt不等。沿着I2的观测，还在夜间观测了IO、OIO和NO3。令人惊讶的是，IO和OIO分别在高达2.5和10.8 ppt的混合比下被检测到。一个模型表明，I2和NO3之间的反应是这些自由基的可能的夜间来源。BrO混合比从低于夜间的检测限（1 ppt）到日出后的第一个小时内的最大值6 ppt不等。溴化学模式被用来模拟的BrO自由基的昼夜行为，demonstrating-卤素循环通过海盐气溶胶的重要性。在同一次观测中，利用天顶差分吸收光谱仪（DOAS）测定了日出时NO3浓度随太阳天顶角（SZA）的变化，并由此得到了对流层NO3浓度的垂直分布。有几次，在最初的2公里内观察到NO3的正梯度，可能是由于二甲基硫化物（DMS）在海洋表面去除NO3。
Time series observations of molecular iodine (I2), iodine oxides (IO, OIO), bromine oxide (BrO), and the ni- trate radical (NO3) in the mid-latitude coastal marine bound- ary layer (MBL) are reported. Measurements were made us- ing a new long-path DOAS instrument during a summertime campaign at Mace Head on the west coast of Ireland. I2 was detected using the B 3 5(0 + ) X 1 6 + electronic transition be- tween 535 and 575 nm. The I2 mixing ratio was found to vary from below the detection limit ( 5 ppt) up to a night- time maximum of 93 ppt. Along with I2, observations of IO, OIO and NO3 were also made during the night. Surprisingly, IO and OIO were detected at mixing ratios up to 2.5 and 10.8 ppt, respectively. A model is employed to show that the reaction between I2 and NO3 is the likely nighttime source of these radicals. The BrO mixing ratio varied from below the detection limit at night ( 1 ppt) to a maximum of 6 ppt in the first hours after sunrise. A bromine chemistry model is used to simulate the diurnal behaviour of the BrO radical, demon- strating the importance of halogen recycling through sea-salt aerosol. In the same campaign a zenith sky DOAS was em- ployed to determine the column density variation of NO3 as a function of solar zenith angle (SZA) during sunrise, from which vertical profiles of NO 3 through the troposphere were obtained. On several occasions a positive gradient of NO3 was observed over the first 2 km, possibly due to dimethyl sulphide (DMS) removing NO3 at the ocean surface.