Christman Field Latest Observations
Date Time
MST
Temp
°F
RH
%
DewPt
°F
Wind
mph
Dir
°
Gust
mph
Dir
°
Press
in Hg
Solar
W/m^2
Prec
in
2019-09-16 14:30 89.2 12.1 30.1 5.1 150 8.7 149 24.728 725.2 0.00
2019-09-16 14:25 89.9 12.0 30.6 6.2 146 9.2 139 24.748 772.6 0.00
2019-09-16 14:20 89.8 12.1 30.6 7.0 122 11.3 134 24.740 770.1 0.00
2019-09-16 14:15 89.8 12.8 32.1 5.5 72 9.3 121 24.763 802.0 0.00
2019-09-16 14:10 90.7 12.3 31.7 7.0 109 11.9 118 24.757 857.0 0.00
2019-09-16 14:05 91.5 11.6 31.0 6.0 121 17.9 179 24.745 887.0 0.00
2019-09-16 14:00 89.5 11.8 29.8 2.4 176 6.1 230 24.738 905.0 0.00
2019-09-16 13:55 88.4 11.8 29.1 6.1 244 8.2 220 24.723 839.0 0.00
2019-09-16 13:50 87.9 12.5 30.1 6.8 264 10.4 233 24.750 679.2 0.00
2019-09-16 13:45 88.4 12.5 30.4 4.6 302 6.7 213 24.752 834.0 0.00
2019-09-16 13:40 88.1 12.5 30.1 4.7 241 8.3 191 24.760 847.0 0.00
2019-09-16 13:35 88.9 12.6 30.9 6.1 135 10.6 141 24.764 883.0 0.00
2019-09-16 13:30 88.8 12.6 30.9 5.5 235 9.6 202 24.766 906.0 0.00
2019-09-16 13:25 89.1 12.1 30.2 4.8 135 7.5 151 24.766 907.0 0.00
2019-09-16 13:20 87.3 12.7 29.9 3.4 151 8.1 136 24.767 790.1 0.00
2019-09-16 13:15 86.4 13.1 30.0 4.5 141 7.0 137 24.768 453.6 0.00
2019-09-16 13:10 85.9 14.2 31.5 3.4 144 7.7 116 24.769 385.8 0.00
2019-09-16 13:05 85.9 12.9 29.2 3.5 78 7.7 93 24.770 329.3 0.00
2019-09-16 13:00 86.2 13.4 30.5 5.3 93 8.7 125 24.771 325.0 0.00
2019-09-16 12:55 87.3 13.2 30.9 5.6 115 8.3 81 24.771 386.8 0.00
2019-09-16 12:50 88.0 12.9 30.8 4.9 82 7.3 82 24.773 818.0 0.00
2019-09-16 12:45 87.2 13.2 30.7 6.1 138 9.1 154 24.774 832.0 0.00
2019-09-16 12:40 86.2 13.6 30.8 6.2 92 10.0 142 24.775 556.3 0.00
2019-09-16 12:35 85.4 13.6 30.1 6.8 124 10.8 126 24.774 452.3 0.00
2019-09-16 12:30 85.4 14.5 31.7 7.3 141 12.1 133 24.773 431.1 0.00
2019-09-16 12:25 85.6 14.2 31.3 8.1 152 11.0 149 24.771 415.6 0.00
2019-09-16 12:20 85.7 13.1 29.3 5.8 119 9.6 127 24.771 494.2 0.00
2019-09-16 12:15 86.6 12.7 29.3 5.6 156 9.8 127 24.775 456.1 0.00
2019-09-16 12:10 87.6 12.9 30.6 7.2 131 10.6 130 24.776 888.0 0.00
2019-09-16 12:05 87.1 13.4 31.1 6.5 151 10.7 164 24.776 875.0 0.00
CIRA

Cooperative Institute for Research in the Atmosphere

Effects of Midwinter Arctic Leads on Boundary Layer Clouds

February 7, 2019 1:30 pm
ATS West 121

Presented by: Steven Krueger

Hosted by: Dave Randall

Visiting from the University of Utah


Leads are quasi-linear openings within the interior of the polar ice pack, where the ocean is exposed directly to the atmosphere. Due to the extreme air-water temperature contrast (20 to 40 K), turbulent and radiative heat fluxes over leads can be two orders of magnitude larger than those over the ice surface in winter and thus dominate the wintertime heat budget of the Arctic boundary layer. Cold-season leads may also produce boundary layer clouds that extend tens of kilometers downwind. These clouds can spatially and temporally extend the impacts of leads on the Arctic surface heat budget. We are using multi-source observations and a 3D cloud-resolving model to understand the impact of leads on the boundary layer clouds. We have used measurements from the ARM cloud radar at Barrow and the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on board Aqua to establish statistical associations between large-scale lead fraction and low cloud occurrence. We expected low cloud occurrence frequency to increase with the large-scale lead flux (lead fraction x calculated sensible heat flux per unit area over open leads). However, we found just the opposite. Low cloud occurrence frequency from CloudSat-CALIPSO over a large-scale region also increased with the large-scale lead flux. Motivated by these results, a 3D cloud-resolving model, System for Atmospheric Modeling (SAM), was used to explore the underlying physics. We found that a wide recently frozen lead produces large sensible heat fluxes, but reduced latent heat fluxes, and consequently produces thinner and less extensive low-level clouds. This result provides a plausible explanation for the counterintuitive observational results: The observed high lead fraction must largely consist of newly refrozen leads which produce less low-level cloudiness. Our results emphasize the need to differentiate, in observations and in models, recently refrozen leads from open-water leads and from thicker ice.

 

Link to colloquia page: https://www.atmos.colostate.edu/colloquia/