An evaluation and comparison of microphysics fields in Dennis (2005) at various lifecycle stages
Eric Meyers
Atlantic Oceanographic and Meteorological Laboratory Hurricane Research Division Millersville University Eric.C.Meyers@noaa.gov Dr. Robert Rogers 01 August 2006
OUTLINE
Background – A Brief Look Back at Dennis (2005) An Incentive – Modeled v. Observed INTENSITY Motivation Methodology Analysis/Findings A qualitative comparison between OBSERVATIONS and MM5 SIMULATION of Dennis (2005) A closer look at the microphysical evolution in the MM5 SIMULATION A peek at a quantifiable comparison between OBSERVATIONAL precipitation probe data and MM5 SIMULATION Summary Future Assignments Acknowledgements
Background – DENNis ‘05
MM5 Simulation
NOAA P-3 Missions
Auto-moving inner nest capability Goddard 3-class ice bulk microphysical parameterization scheme Kain-Fritsch convective parameterization for 45- and 15-km grid meshes No convective parameterization for 5- and 1.67-km grid meshes
Dropsondes LF radar Precipitation imaging probe
Visible satellite imagery courtesy NRL-Monterey
INTENSITY ISSUE - DENNis ‘05
Motivation
Advent of high-resolution models mandates a statistical means of comparing modeled microphysics with observations To initiate the effort to improve:
Microphysical parameterization schemes Simulated distributions of latent heat release (spatial and temporal) Tropical cyclone intensity forecasts Rainfall predictions “To serve society’s needs for weather and water information” “Understand, Describe, Assess, & Predict”
NOAA’s Strategic Plan Mission Goal 3
Methodology
Qualitative Comparison
Hypothesis
Attempt to validate model thermodynamics MM5 simulation exhibits various temporal differences in the distributions, averages, and gradients of microphysics fields during the organizational stage of Dennis (2005) These quantifiable differences in microphysics can be statistically compared with observed fields of vertical velocity, reflectivity, and hydrometeor concentrations, with the intent to detect biases in the model
Statistical Model Analysis
A Preliminary Quantitative Comparison
Compare structural features and statistical distributions of hydrometeor mixing ratio, reflectivity, and vertical motion “EARLY” - 18:00 Z 05 July 2005 through 00:00 Z 06 July 2005 (Tropical Storm Dennis – best track) “LATE” – 06:00 Z 07 July 2005 through 12:00 Z 07 July 2005 (Hurricane Dennis – best track) “Convective”, “Stratiform”, and “Other”
Precipitation imaging probe data v. simulated precipitation Sampling volume v. model resolution
Qualitative comparison
13 dropsondes derived equivalent potential temperature 20:38-22:30 UTC 05 July 2005 950 hPa NOAA P-3 LF reflectivity 21:59 UTC 05 July 2005 650 hPa
MM5 derived equivalent potential temperature 21:00 UTC 05 July 2005 950 hPa
MM5 reflectivity 22:00 UTC 05 July 2005 700 hPa
A LiMiTED PERsPECTiVE…
convective region 22:00 UTC 05 July 2005
Rainwater mixing ratio
0°C Graupel mixing ratio
convective region
09:00 UTC 07 July 2005
REFLECTIVITY
Contoured Frequency by Altitude Diagrams (CFADs)
bin size: 5 dBZ 11 km
18:00 UTC 05 July 2005 – 00:00 UTC 06 July 2005
CONVECTIVE REGIONS
bin size: 5 dBZ 11 km
06:00 UTC Contoured Frequency by Altitude Diagram (CFAD) – 07 July 2005 12:00 UTC 07 July 2005
Vertical Velocity
18:00 UTC 05 July 2005 – 00:00 UTC 06 July 2005
CONVECTIVE
bin size: 1 m/s
06:00 UTC 07 July 2005 – 12:00 UTC 07 July 2005
GRAUPEL
CONVECTIVE REGIONS
INITIAL Quantitative comparison
01:58:49 Z - 02:01:23 Z 7 July 2005 mean T = 1.67 °C median T = 1.61 °C
ICE Precipitation Imaging Probe RAIN
6.4 mm
Summary
Set out to explore, both qualitatively and statistically, differences in the evolution of simulated microphysics fields
“EARLY” “LATE”
Employed a unique statistical (and thus representative) framework for evaluating modeled microphysical parameterization schemes
Contoured Frequency by Altitude Diagrams (CFADs) Mean profiles
Independent from observational data, determined that the MM5 simulation exhibits significant temporal variability in microphysics fields, through a unique vertical evolution of hydrometeor concentrations
Distributions of reflectivity and vertical motion are broader during “early” than during “late” period, especially above the melting level Isolated “early” convective cores likely contribute to the majority of vertical mass transport, lofting super-cooled raindrops to higher levels and increasing graupel mixing ratio
Future assignments
To determine the statistical significance of differences evident in the prepared statistical analyses of modeled microphysics fields To perform statistical analyses of observations: Post-processed dropsonde data Reliable microphysical probe measurements Coordinated NOAA P-3 and NASA ER-2 Doppler velocities To compare the temporal evolution of microphysics fields in the MM5 simulation (manifested in the statistical analyses I have prepared) with these observations To pinpoint biases in the model To evaluate the microphysical parameterization schemes To continue simulations of Dennis (including an extension to the mature stage, when Dennis was over the eastern Gulf of Mexico), with specific efforts to improve the simulation of intensity Ultimately, to use an enhanced modeling of microphysics to improve forecasts of tropical cyclone intensity and rainfall, an obvious benefit to public safety
Acknowledgements
Collaborators Black, Robert - researcher HRD Feuer, Steve - researcher HRD Marks, Frank, PhD - director HRD Ortt, Derek - graduate student RSMAS Rogers, Robert, PhD - mentor and researcher HRD Uhlhorn, Eric – researcher HRD Valde, Krystal – CIMAS research associate Papers Cifelli, R., Peterson, W. A., Carey, L. D., & Rutledge, S. A. (2002). Radar observations of the kinematic, microphysical, and precipitation characteristics of two MCSs in TRMM LBA. J. of Geophysical Research, 107, 44-1-44-15. Rogers, R. F., Black, M. L., Chen, S. S., Black, R. A. (2006). An evaluation of microphysical fields from mesoscale model simulations of tropical cyclones. Part I: Comparisons with observations. J. of Atmospheric Sciences, in review. Yuter, S. E. & Houze, R. A. (1994). Three-dimensional kinematic and microphysical evolution of Florida cumulonimbus. Part III: Vertical mass transport, mass divergence, and synthesis. Mon. Wea. Rev., 123, 1946-1983.
I now invite any
You may have!