Impacts on cloud radiative effects induced by coexisting aerosols converted from international sh...

Impacts on cloud radiative effects induced by coexisting aerosols converted from international shipping and maritime DMS emissions

国际航运排放（ISE），特别是二氧化硫，可以通过与氧化成硫酸盐气溶胶后的云和辐射相互作用来影响全球辐射预算。更好地了解估算ISE云辐射效应（CREs）的不确定性在气候科学中具有重要意义。许多国际航运轨道涵盖了大量天然二甲基硫醚（DMS）排放的海洋。在气溶胶浓度相对较低的广阔海洋区域，这两个主要气溶胶源之间的相互作用是一个有趣但却很难解决的问题，混淆了ISE的CREs的估计。使用包含两个具有不同气溶胶混合配置的气溶胶模块的地球系统模型，我们得出了一个重要的全球净ISE（-0.153）w ^m -2，标准误差为±0.004w ^m -2）使用符合当前船舶排放法规的排放。这种全球净CRE将变得更弱，实际上微不足道（-0.001w ^m -2标准误差为±0.007w ^m -2）如果采用更严格的规定。然后我们揭示了由于气溶胶浓度和云响应之间的次线性关系，当模拟中规定较低的DMS发射时，ISE诱导的CRE将实现显着增强。此外，该研究还表明，某些气溶胶过程（如混合状态）的表示可以影响ISE诱导的CRE的大小和模式。这些发现表明，考虑到DMS的可变性，重新评估了ISE诱导的CRE。

Impacts of DMS emissions on cloud responses to international shipping emissions. (a) Cloud radiative effects at the TOA (W m−2),(b) column-integrated cloud water path (g m−2), and (c) column-integrated cloud droplet number (×109 m−2). The green, purple, and blue curves respectively represent quantities area-averaged over the North Pacific Ocean (NPO), the North Atlantic Ocean (NAO), and the Southern Ocean (SO), which are shown as red boxes in Fig. 1a. These results are from MARC simulations.

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Impacts on cloud radiative effects induced by coexisting
aerosols converted from international shipping and
maritime DMS emissions

Sulfate aerosols are efficient cloud condensation nuclei
(CCN) and control the formation of marine clouds and their
micro- and macrophysical properties (McCoy et al., 2015).

Aerosol DREs are represented by coupling between aerosols and radiation.
Aerosol CREs are included by activating aerosols to
work as CCN and ice nuclei in the stratiform clouds (Morrison
and Gettelman, 2008; Gettelman et al., 2010). Parameterization
of aerosol activation is based on particle size and
hygroscopicity of aerosols. Similar to other climate models,
CAM5 does not directly include aerosol’s influence through
microphysics on convective clouds, but it allows aerosols to
influence convective clouds indirectly, such as by aerosol’s
effect on circulation, surface evapotranspiration, and so on.

The sulfate aerosols from shipping emissions
are highly efficient CCN and thus can increase the CDNC,
which in turn affects CWP. Note that cloud area fraction does
not exhibit any significant changes due to shipping emissions
(not shown).

Our results indicate that DMS is a significant source to CCN in the extremely clean
polar regions in both hemispheres

By comparing Fig. 8 with Fig. 12 we also observe significantly
different impacts of DMS emissions on cloud response
to shipping emissions (i.e., the slopes of these curves).
MAM3 simulates a weaker impact of DMS emissions on
cloud response to shipping emissions than MARC, indicating
a weaker nonlinear competing effect for CCN between
DMS and shipping emissions in MAM3 than MARC.

It is worth noting that DMS is a significant source to CCN in the extremely
clean polar regions in both hemispheres

The relationship between ambient aerosol number concentrations and activated aerosols parameterized in the aerosol activation scheme. This relationship is retrieved when the temperature, pressure, and updraft velocity are 10°C, 800 mbar, and 5 m s−1,respectively. The aerosol population are assumed to be completely soluble and lognormally distributed with a geometric mean radius 5 of 0.01 m and geometric standard deviation of 2.5 (Abdul-Razzak et al., 1998).

看一看高速公路网或者河流的位置的情况！
和浓度图叠加起来

NAO,ENSO等分年份，做空间相关分析！