Spectral characterization, radiative forcing and pigment content of coastal Antarctic snow algae: approaches to spectrally discriminate red and green communities and their impact on snowmelt
Spectral characterization, radiative forcing and pigment content of coastal Antarctic snow algae: approaches to spectrally discriminate red and green communities and their impact on snowmelt
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DOI：
10.5194/tc-15-133-2021
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发表时间：
2021-01-13
期刊：
影响因子：
5.2
通讯作者：
Cordero, Raul R.
中科院分区：
文献类型：
--
作者：
Khan, Alia L.;Dierssen, Heidi M.;Cordero, Raul R.
在这里，我们提出了南极半岛（AP）地区雪藻的辐射强迫（RF）估计，这些估计来自太阳辐射的多年测量以及2018年夏季南方短暂实地考察期间收集的红色和绿色雪藻的地面高光谱特征。我们的分析包括三个水华地点样本的色素含量。在可见光谱范围内，雪中的藻类生物量和藻类减少量之间存在良好的相关性。相对于干净的雪，明显的绿色斑块减少了雪的覆盖率约40%，红色斑块减少了约20%。然而，与绿色群落相比，红色群落每毫克色素吸收相当多的光，特别是在绿色波长中。基于我们的研究结果，应该可以使用蓝色、绿色和红色波长的Sentinel-2波段来区分红色和绿色藻类。绿色的瞬时RF平均值（180 W m（-2））是红色社区（88 W m（-2））的两倍，最大值为228 W m（-2）。根据帕尔默站多年的太阳辐射测量结果，在生长高峰期，这转化为平均日RF类似于26 W m（-2）（绿色），类似于13 W m（-2）（红色）-与中纬度灰尘属性能够促进融雪。这导致了类似于2522米（3）的雪融化的绿色藻类和类似于1218米（3）的雪融化的红色藻类每年在夏季，这表明雪藻在积雪融化中发挥了重要作用，在AP地区，它们发生。我们建议RF雪藻对融雪的影响，在未来的估计在AP地区的南极无冰扩张。
Here, we present radiative forcing (RF) estimates by snow algae in the Antarctic Peninsula (AP) region from multi-year measurements of solar radiation and ground-based hyperspectral characterization of red and green snow algae collected during a brief field expedition in austral summer 2018. Our analysis includes pigment content from samples at three bloom sites. Algal biomass in the snow and albedo reduction are well-correlated across the visible spectrum. Relative to clean snow, visibly green patches reduce snow albedo by similar to 40 % and red patches by similar to 20 %. However, red communities absorb considerably more light per milligram of pigment compared to green communities, particularly in green wavelengths. Based on our study results, it should be possible to differentiate red and green algae using Sentinel-2 bands in blue, green and red wavelengths. Instantaneous RF averages were double for green (180 W m(-2)) vs. red communities (88 W m(-2)), with a maximum of 228 W m(-2). Based on multi-year solar radiation measurements at Palmer Station, this translated to a mean daily RF of similar to 26 W m(-2) (green) and similar to 13 W m(-2) (red) during peak growing season - on par with midlatitude dust attributions capable of advancing snowmelt. This results in similar to 2522 m(3) of snow melted by green-colored algae and similar to 1218 m(3) of snow melted by red-colored algae annually over the summer, suggesting snow algae play a significant role in snowmelt in the AP regions where they occur. We suggest impacts of RF by snow algae on snowmelt be accounted for in future estimates of Antarctic ice-free expansion in the AP region.