Vertical distributions of dust and sea-salt aerosols over Puerto Rico during PRIDE measured from a light aircraft
Vertical distributions of dust and sea-salt aerosols over Puerto Rico during PRIDE measured from a light aircraft
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DOI：
10.1029/2002jd002544
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发表时间：
2003-10
影响因子：
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通讯作者：
H. Maring;D. L. Savioe;M. Izaguirre;L. Custals;J. Reid
中科院分区：
文献类型：
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作者：
H. Maring;D. L. Savioe;M. Izaguirre;L. Custals;J. Reid
[1] 我们开发了轻型飞机气溶胶包 (LAAP)，用于测量高达 ∼4000 m asl 的气溶胶特性。 LAAP 通过经验和理论修正，可靠地测量了气溶胶的微物理和化学特性。在 2000 年 6 月至 7 月的波多黎各沙尘实验 (PRIDE) 期间，我们测量了热带北大西洋上空的气溶胶特性。根据气溶胶过滤器样本和测量的气溶胶粒径分布，我们（1）模拟了海盐气溶胶浓度随海拔的变化，表征了海盐浓度随海拔的快速下降； (2) 没有发现海洋边界层（MBL）上方存在海盐的证据； (3) 观察到撒哈拉空气层 (SAL) 中的矿物粉尘超过 170 µg m−3。 MBL 和 SAL 之间垂直分布的显着变化以及灰尘尺寸分布的微小差异表明，灰尘特性更多地取决于单独的传输历史，而不是波多黎各附近 MBL 和 SAL 之间的相互作用。相对恒定的灰尘尺寸分布随海拔高度的变化表明，要么（1）灰尘气溶胶一旦进入“沉积层”就不会重新移动，要么（2）干沉积可以去除与颗粒尺寸无关的灰尘颗粒。在低（~25%）和高（~93%）相对湿度下测量的粉尘尺寸分布无法区分。一个简单的模型计算表明，在相对湿度从 25% 变化到 95% 的情况下，夏季热带北大西洋上空的尘埃颗粒几何直径增加 <6%。因此，当相对湿度 <95% 时，这些灰尘颗粒的光学特性不应发生变化。
[1] We developed the Light Aircraft Aerosol Package (LAAP) to make measurements of aerosol properties up to ∼4000 m asl. The LAAP reliably measured, with empirical and theoretical corrections, aerosol microphysical and chemical properties. During the Puerto Rico Dust Experiment (PRIDE), June–July 2000, we measured aerosol properties over the tropical North Atlantic. On the basis of aerosol filter samples and measured aerosol size distributions, we (1) modeled sea-salt aerosol concentration with altitude, characterizing the rapid decrease in sea-salt concentration with altitude; (2) found no evidence of sea salt above the marine boundary layer (MBL); and (3) observed mineral dust in the Saharan Air Layer (SAL) to exceed 170 μg m−3. Substantial variability in the vertical distribution and small differences in the size distribution of dust between the MBL and SAL suggested dust properties were more dependent on the separate transport histories than the interaction between the MBL and SAL near Puerto Rico. Relatively constant dust size distributions with altitude suggested either (1) no relofting of dust aerosols once they get into the “deposition layer” or (2) dry deposition removes dust particles independent of particle size. Dust size distributions measured at low (∼25%) and high (∼93%) relative humidity were indistinguishable. A simple model calculation suggests dust particles over the tropical North Atlantic during summer increase their geometric diameter <6% for a relative humidity change from 25 to 95%. Thus optical properties of those dust particles should not change for relative humidities <95%.