Ice fog was observed below about 700 mb where vapor mixing ratio (Fig.
Comparisons are then performed to assess the accuracy of the GOES-R algorithms for detecting ice fog conditions.
Three ice fog events (16,17, and 21 January) observed during this time period occurred at temperature <-30[degrees]C where RH was close to 100%.
Based on in situ observations at the surface, the occurrence of the ice fog, frost, and light snow is summarized in Table 2.
During fog-free conditions, the spectra from both sensors indicated a smooth continuation (not shown); however, during ice fog conditions, the Climatronic Aerosol Profiler spectra shifted to the right over larger size ranges (size >0.5 [micro]m), indicating the fraction of aerosols particles growing to ice fog particles.
For larger particle sizes (>10 [micro]m), the Ground Cloud Imaging Probe images and spectral measurements during the project clearly indicated ice fog existence but fog crystal shapes could not be clearly discriminated.
To assess the visibility uncertainties, visibility from the FD12P ([Vis.sub.fd]) and Sentry ([Vis.sub.se] are plotted against each other for an ice fog event (Fig.
The model postprocessor calculates visibility using the extinction as a function of cloud ice water content (Stoelinga and Warner 1999); however, this tends to underestimate the ice fog water content.
If both ice water content and ice crystal number concentration can be known from a forecasting model at each time step, then ice fog visibility can be predicted.