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
2020-02-28 07:25 28.4 65.8 18.4 3.3 303 8.6 303 25.042 109.4 0.00
2020-02-28 07:20 28.0 59.7 15.8 5.1 1 8.4 345 25.042 92.5 0.00
2020-02-28 07:15 28.6 61.9 17.3 2.3 332 6.1 354 25.041 74.5 0.00
2020-02-28 07:10 26.8 59.7 14.6 1.1 188 4.2 290 25.037 58.0 0.00
2020-02-28 07:05 26.3 67.2 16.8 2.7 201 4.6 206 25.034 43.5 0.00
2020-02-28 07:00 25.6 67.7 16.4 4.6 228 9.1 310 25.036 28.2 0.00
2020-02-28 06:55 25.2 64.4 14.9 5.0 273 7.6 156 25.034 13.0 0.00
2020-02-28 06:50 23.8 67.7 14.7 3.5 183 6.2 188 25.038 12.1 0.00
2020-02-28 06:45 25.2 65.9 15.4 2.6 236 5.6 240 25.036 7.3 0.00
2020-02-28 06:40 26.6 63.6 15.9 3.8 229 9.3 245 25.034 5.0 0.00
2020-02-28 06:35 25.9 58.5 13.4 3.4 135 5.3 222 25.033 3.1 0.00
2020-02-28 06:30 24.8 62.3 13.8 5.6 221 14.9 268 25.036 1.7 0.00
2020-02-28 06:25 22.6 71.3 14.7 8.0 268 18.6 281 25.030 0.8 0.00
2020-02-28 06:20 22.5 70.3 14.3 1.5 130 4.0 130 25.033 0.2 0.00
2020-02-28 06:15 23.0 67.7 13.9 0.4 244 2.5 140 25.028 0.2 0.00
2020-02-28 06:10 23.3 67.5 14.1 1.5 167 2.5 333 25.029 0.2 0.00
2020-02-28 06:05 23.8 68.9 15.1 0.5 333 2.1 333 25.023 0.1 0.00
2020-02-28 06:00 23.6 65.8 13.8 0.3 333 2.1 333 25.022 0.1 0.00
2020-02-28 05:55 23.8 65.9 14.0 1.9 333 2.3 333 25.023 0.1 0.00
2020-02-28 05:50 23.2 67.6 14.1 0.8 333 2.2 333 25.023 0.1 0.00
2020-02-28 05:45 23.5 70.1 15.2 1.5 308 3.2 321 25.023 0.1 0.00
2020-02-28 05:40 23.9 65.9 14.1 1.1 316 2.6 315 25.022 0.0 0.00
2020-02-28 05:35 22.1 72.4 14.6 0.0 317 0.0 333 25.020 0.1 0.00
2020-02-28 05:30 22.8 66.9 13.5 1.4 333 3.6 333 25.020 0.1 0.00
2020-02-28 05:25 23.5 64.3 13.2 0.5 236 2.7 236 25.017 0.0 0.00
2020-02-28 05:20 23.4 64.5 13.2 1.2 236 2.6 236 25.017 0.0 0.00
2020-02-28 05:15 22.9 65.6 13.1 0.9 201 3.2 199 25.018 0.0 0.00
2020-02-28 05:10 24.1 65.6 14.2 0.1 248 1.0 253 25.016 0.0 0.00
2020-02-28 05:05 24.1 64.3 13.8 0.0 252 0.0 253 25.017 0.0 0.00
2020-02-28 05:00 24.6 61.6 13.2 1.0 253 4.1 249 25.014 0.0 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/