Measurements and modelling of molecular iodine emissions, transport and photodestruction in the coastal region around Roscoff
Measurements and modelling of molecular iodine emissions, transport and photodestruction in the coastal region around Roscoff
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DOI：
10.5194/acp-10-11823-2010
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发表时间：
2010-01-01
影响因子：
6.3
通讯作者：
McFiggans, G.
中科院分区：
文献类型：
--
作者：
Leigh, R. J.;Ball, S. M.;McFiggans, G.
碘排放量的主要六个大型藻类物种在沿海地区罗斯科夫，法国，已被建模，以支持反应性卤素在海洋边界层实验（RHaMBLe）在2006年9月进行。一个二维模型被用来探索地理上可分辨的区域排放之间的关系（根据该地区海藻床的地图和实验室先前测量的海藻I-2排放率）以及分别由位于海岸线上的宽带光腔衰荡光谱（BBCRDS）仪器和长光程差分光学吸收光谱（LP-DOAS）进行的I-2现场点和线测量仪器采样通过延长的光路到达离岸岛屿。模拟的点和线I-2浓度定量比较BBCRDS和LP-DOAS测量，并提供了发射场和不同的测量几何之间的联系，用于量化大气中的I-2浓度在RHaMBLe。在最低潮期间，罗斯科夫周围100 km（2）区域的I-2总排放量计算为每秒1.7x10（19）个分子。在夜间，该模型复制了I-2浓度高达50 pptv测量沿着LP-DOAS仪器的视线，并预测在某些条件下几百pptv的尖峰。点I-2浓度高达50 pptv也计算在测量网站，在广泛的协议与BBCRDS的意见。白天测得的浓度的I-2在该网站与模拟生产和运输过程。然而，大量的再循环的光解的I-2需要的模型定量匹配测量的浓度。这一结果证实了以前的建模碘和氮氧化物化学在半污染的海洋边界层，提出了一种机制，通过形成，运输和随后的反应的IONO 2水库化合物回收I-2。本文提出的方法提供了一个工具，用于连接空间上不同的测量不均匀和随时间变化的发射场。
Iodine emissions from the dominant six macroalgal species in the coastal regions around Roscoff, France, have been modelled to support the Reactive Halogens in the Marine Boundary Layer Experiment (RHaMBLe) undertaken in September 2006. A two-dimensional model is used to explore the relationship between geographically resolved regional emissions (based on maps of seaweed beds in the area and seaweed I-2 emission rates previously measured in the laboratory) and in situ point and line measurements of I-2 performed respectively by a broadband cavity ringdown spectroscopy (BBCRDS) instrument sited on the shoreline and a long-path differential optical absorption spectroscopy (LP-DOAS) instrument sampling over an extended light path to an off-shore island. The modelled point and line I-2 concentrations compare quantitatively with BBCRDS and LP-DOAS measurements, and provide a link between emission fields and the different measurement geometries used to quantify atmospheric I-2 concentrations during RHaMBLe. Total I-2 emissions over the 100 km(2) region around Roscoff are calculated to be 1.7x10(19) molecules per second during the lowest tides. During the night, the model replicates I-2 concentrations up to 50 pptv measured along the LP-DOAS instrument's line of sight, and predicts spikes of several hundred pptv in certain conditions. Point I-2 concentrations up to 50 pptv are also calculated at the measurement site, in broad agreement with the BBCRDS observations. Daytime measured concentrations of I-2 at the site correlate with modelled production and transport processes. However substantial recycling of the photodissociated I-2 is required for the model to quantitatively match measured concentrations. This result corroborates previous modelling of iodine and NOx chemistry in the semi-polluted marine boundary layer which proposed a mechanism for recycling I-2 via the formation, transport and subsequent reactions of the IONO2 reservoir compound. The methodology presented in this paper provides a tool for linking spatially distinct measurements to inhomogeneous and temporally varying emission fields.