Web Page of Dr. Penny Rowe

Dr. Penny Rowe

Research Scientist
NorthWest Research Associates

    Refractive indices
    Single scattering params
Educational Materials
    PENGUIN: gitHub
Computer Code

Complex refractive indices of liquid water
from 240 to 300 K

Supercooled liquid water is present in mixed-phase and liquid-only clouds in the polar regions and at high altitudes globally. The radiative properties of these clouds depend on the complex refractive index (CRI) of liquid water, which laboratory measurements have shown to be temperature dependent. Radiative transfer calculations have shown that this has important consequences for the infrared radiance of clouds containing supercooled liquid water (Rowe et al. 2013). Despite this, most radiative transfer and climate models typically use CRI based on room-temperature liquid water.


To address the need for a set of temperature-dependent single-scattering parameters for computing radiative transfer through supercooled liquid cloud, we have compiled spectra of CRI at temperatures of 240, 253, 263, and 273 K, based on a measured literature values and theoretical work.

CRI for supercooled liquid water will also soon be posted on RefractiveIndex.info

Please acknowledge use of these datasets in publications.

Single Scattering parameters

From these CRI, we computed single-scattering parameters, including the single-scattering albedo and Legendre moments. Please note that the single-scattering parameters have been updated, A publication is pending, and the values here should be updated by summer 2020, so please check back then. We also provided literature values for water ice and for liquid water at 300 K. For the latter, we suggest the CRI of Bertie and Lan, rather than that of Downing and Williams.


Rowe, P. M., Cox, C., Neshyba, S., & Walden, V. P. (2019). Toward autonomous surface-based infrared remote sensing of polar clouds: retrievals of cloud optical and microphysical properties. Atmospheric Measurement Techniques, 12(9), 5071–5086. http://doi.org/10.5194/amt-12-5071-2019

Rowe, P. M., Neshyba, S., & Walden, V. P. (2013). Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds. Atmospheric Chemistry and Physics, 13(23), 11925–11933.

Bertie, J. E., & Lan, Z. (1996). Infrared Intensities of Liquids XX: The Intensity of the OH Stretching Band of Liquid Water Revisited, and the Best Current Values of the Optical Constants of H2O(l) at 25°C between 15,000 and 1 cm-1. Applied Spectroscopy, 50(8), 1047–1057. http://doi.org/10.1366/0003702963905385.

Downing, H. D., & Williams, D. (1975). Optical constants of water in the infrared. Journal of Geophysical Research, 80(12), 1656–1661.

Warren, S. G., & Brandt, R. E. (2008). Optical constants of ice from the ultraviolet to the microwave: A revised compilation. Journal of Geophysical Research, 113(D14), D14220. http://doi.org/10.1029/2007JD009744.


This work was funded by NSF Office of Polar Programs award 1543236 and NSF CHE-1807898.