the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Broadband and filter radiometers at Ross Island, Antarctica: Detection of cloud ice phase versus liquid water influences on shortwave and longwave radiation
Kristopher Scarci
Ryan Scott
Madison Ghiz
Andrew Vogelmann
Dan Lubin
Abstract. Surface radiometer data from Ross Island, Antarctica, collected during the austral summer 2015–16 by the US Department of Energy Atmospheric Radiation Measurement (ARM) program West Antarctic Radiation Experiment (AWARE), are used to evaluate how shortwave and longwave irradiance respond to changing cloud properties as governed by contrasting meteorological regimes. Shortwave atmospheric transmittance is derived from pyranometer measurements, and cloud conservative-scattering optical depth is derived from filter radiometer measurements at 870 nm. With onshore flow associated with marine air masses, clouds contain mostly liquid water. With southerly flow over the Transantarctic Mountains, orographic forcing induces substantial cloud ice water content. These ice and mixed-phase clouds attenuate more surface shortwave irradiance than the maritime-influenced clouds, and also emit less longwave irradiance due to colder cloud base temperature. These detected irradiance changes are in a range that can mean onset or inhibition of surface melt over ice shelves. This study demonstrates how basic and relatively low-cost broadband and filter radiometers can be used to detect subtle climatological influences of contrasting cloud microphysical properties at very remote locations.
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Kristopher Scarci et al.
Status: open (until 25 Oct 2023)
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RC1: 'Comment on egusphere-2023-1665', Anonymous Referee #1, 03 Oct 2023
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This paper uses basic radiometric measurements to calculate cloud optical depths and cloud transmissions and infer the presence of ice or mixed phase clouds. The cloud optical depth calculated using wavelength 870 is not affected by ice clouds whereas broadband shortwave transmission is because of ice bands in the near-infrared. In other words cloud radars, lidars, and other sophisticated equipment are not necessary to obtain fundamentally useful data that can distinguish ice and mixed phase clouds from water clouds.
I think the authors demonstrate their point that fairly fundamental radiation measurements can be used at sites in the Antarctic. However, I am not sure that the measurements that they suggest can detect the 10 W/m^2 changes in the net surface radiation (lines 56-58) that could induce ice melt or retention.
Line 70: indicates about six weeks of measurements; is that correct?
Line 150: "... one describes with a unique large-scale circulation pattern." Is this correctly stated?
A map with labels of the geographic sites discussed in these paragraphs would help for those not familiar with Antarctic geography.
Citation: https://doi.org/10.5194/egusphere-2023-1665-RC1
Kristopher Scarci et al.
Kristopher Scarci et al.
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