(1) (2) (3) Gijs de Boer (1), Edwin W. Eloranta (1), Matthew D. Shupe (2), Taneil Uttal (2), Jennifer Kay (3) ESRL

Transcription

1 Multi-Year Statistics of Mixed-Phase Arctic Stratus at Barrow and Eureka: Process Studies, Assessment of CloudSAT Detection, and Applications to Models Gijs de Boer (1), Edwin W. Eloranta (1), Matthew D. Shupe (2), Taneil Uttal (2), Jennifer Kay (3) (1) (2) ESRL (3)

2 Introduction NP 8 N 7 N Barrow Eureka STATES UNITED BEAUFORT SEA CANADA GREENLAND Barrow: 9/4-11/4 Eureka: 8/5-present High Spectral Resolution Lidar MMCR (35 GHz) Radiosondes

3 Altitude (km) a) 1e!3 1e!4 1e!5 1e!6 1e!7 Introduction AHSRL Backscatter b) 1e!8 1/(m str) 1 Altitude (km) e!1 5e!2 AHSRL Depolarization Altitude (km) c) 1:35 1:4 1:45 1:5 1:55 Time (UT) 1e!2 Percent 2 dbz 1!1!2!3!4 MMCR Reflectivity

4 Introduction Low altitude stratus frequency of up to 7% during transition seasons (Herman and Goody, 1976; Curry et al., 1996) Reduces wintertime net surface cooling by 4-5 W/m 2 (Curry et al., 1996) Commonly observed during several recent Arctic experiments (SHEBA, MPACE, SEARCH, ISDAC) Often long-lived, surviving up to several days at a time (de Boer et al., 28) Difficult to simulate (Klein et al., 28)

5 Property Statistics Single-layer mixed phase 4. stratus observations Altitude (km) hours from Barrow (fall 24) hours from Eureka Time (UT) (fall 25-27)

6 Cloud Macrophysical Statistics Frequency (%) % (Barrow) 8% (Eureka)

7 Cloud Macrophysical Statistics Z base (m) Cld Thickness (m) m (Barrow) 167 m (Eureka) 674 m (Barrow) 331 m (Eureka)

8 Cloud Macrophysical Statistics Z base (m) Cld Thickness (m) m (Barrow) 167 m (Eureka) 674 m (Barrow) 331 m (Eureka)

9 Cloud Macrophysical Statistics Z base (m) Cld Thickness (m) m (Barrow) 167 m (Eureka) 674 m (Barrow) 331 m (Eureka)

10 Cloud Macrophysical Statistics Z base (m) Cld Thickness (m) m (Barrow) 167 m (Eureka) 674 m (Barrow) 331 m (Eureka)

11 Simulation 171 ice water path (g m -2 ) For Pe (Klein et al., 29) liquid water path (g m -2 )

12 Simulation Temperature (K)

13 Simulation (Shupe et al., 28)

14 Simulation (Shupe et al., 28)

15 Simulation LWF Cloud Top Temperature (K)

16 Simulation Number Density (#/L) d eff ( m) 2 a) b) c) d eff ( m) Number Density (#/L) 2 a) b) c) TWC (g/m 3 ) TWC (g/m 3 ) d) 1-1 d) IWC (g/m 3 ) IWC (g/m 3 ) In-Cloud Sub-Cloud

17 Measurement Coverage Map courtesy of NOAA NGDC

18 Measurement Coverage Map courtesy of NOAA NGDC

19 CloudSAT (Jennifer Kay)

20 CloudSAT 7 Z top (m) /312 cases ztop < 1 m 1 Reflectivity (dbz) 1!1!3!5 26/312 cases Zrad < -29 dbz

21 Summary -Low, single-layer mixed-phase clouds commonly observed at both Eureka and Barrow -Differences in macrophysical and microphysical characteristics between different locations and inter-seasonal variation at Eureka -Large available database to improve and validate simulation of these mixed-phase clouds (as well as others) -Some low level clouds may easily be missed by CloudSAT

22 References Curry, J.A., W.B. Rossow, D. Randall, and J.J. Schramm (1996), Overview of Arctic Cloud and Radiation Characteristics, J. Climate, 9, de Boer, G., E.W. Eloranta, and M.D. Shupe (29), Arctic Mixed-Phase Stratiform Cloud Properties from Multiple Years of Surface-Based Measurements at Two High-Latitude Locations, Submitted to JAS. Herman, G. and R. Goody (1976), Formation and Persistence of Summertime Arctic Clouds, J. Atmos. Sci., 33, Klein, S.A., and co-authors (29), Intercomparison of Model Simulations of Mixed- Phase Clouds Observed During the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single-Layer Cloud, Submitted to QJRMS. Shupe, M.D., P. Kollias, P.O.G. Persson, and G.M. McFarquhar (28), Vertical Motions in Arctic Mixed-Phase Stratiform Clouds, J. Atmos. Sci., 65,

23 EXTRA SLIDES v

24 1 Individual and Cumulative Uptime Percentage 75 Uptime (%) 5 25 Oct 4 Sep 5 Dec 5 Mar 6 Jun 6 Sep 6 Dec 6 Mar 7 Jun 7 Sep 7 Dec 7 Month