Painter T H, Duval B, Thomas W H, Mendez M, Heintzelman S, Dozier J
Institute for Computational Earth System Science, University of California, Santa Barbara, California 93106, USA.
Appl Environ Microbiol. 2001 Nov;67(11):5267-72. doi: 10.1128/AEM.67.11.5267-5272.2001.
We describe spectral reflectance measurements of snow containing the snow alga Chlamydomonas nivalis and a model to retrieve snow algal concentrations from airborne imaging spectrometer data. Because cells of C. nivalis absorb at specific wavelengths in regions indicative of carotenoids (astaxanthin esters, lutein, beta-carotene) and chlorophylls a and b, the spectral signature of snow containing C. nivalis is distinct from that of snow without algae. The spectral reflectance of snow containing C. nivalis is separable from that of snow without algae due to carotenoid absorption in the wavelength range from 0.4 to 0.58 microm and chlorophyll a and b absorption in the wavelength range from 0.6 to 0.7 microm. The integral of the scaled chlorophyll a and b absorption feature (I(0.68)) varies with algal concentration (C(a)). Using the relationship C(a) = 81019.2 I(0.68) + 845.2, we inverted Airborne Visible Infrared Imaging Spectrometer reflectance data collected in the Tioga Pass region of the Sierra Nevada in California to determine algal concentration. For the 5.5-km(2) region imaged, the mean algal concentration was 1,306 cells ml(-1), the standard deviation was 1,740 cells ml(-1), and the coefficient of variation was 1.33. The retrieved spatial distribution was consistent with observations made in the field. From the spatial estimates of algal concentration, we calculated a total imaged algal biomass of 16.55 kg for the 0.495-km(2) snow-covered area, which gave an areal biomass concentration of 0.033 g/m(2).
我们描述了含有雪衣藻的雪的光谱反射率测量结果，以及一个从机载成像光谱仪数据中反演雪藻浓度的模型。由于雪衣藻细胞在指示类胡萝卜素（虾青素酯、叶黄素、β-胡萝卜素）以及叶绿素a和b的特定波长处有吸收，因此含有雪衣藻的雪的光谱特征与不含藻类的雪不同。含有雪衣藻的雪的光谱反射率与不含藻类的雪的光谱反射率可分离，这是由于在0.4至0.58微米波长范围内的类胡萝卜素吸收以及在0.6至0.7微米波长范围内的叶绿素a和b吸收。缩放后的叶绿素a和b吸收特征的积分（I(0.68)）随藻类浓度（C(a)）而变化。利用关系C(a) = 81019.2 I(0.68) + 845.2，我们对在加利福尼亚州内华达山脉蒂奥加山口地区收集的机载可见红外成像光谱仪反射率数据进行反演，以确定藻类浓度。对于成像的5.5平方千米区域，平均藻类浓度为1306个细胞/毫升，标准偏差为1740个细胞/毫升，变异系数为1.33。反演得到的空间分布与实地观测结果一致。根据藻类浓度的空间估计值，我们计算出在0.495平方千米的积雪覆盖区域内，成像的藻类总生物量为16.55千克，这给出了面生物量浓度为0.033克/平方米。
