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Published byAnja Virtanen Modified over 5 years ago
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LAPS cloud analysis Steve Albers (NOAA/ESRL/GSD/FAB & CIRA) METAR
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Cloud Analysis Flow Chart
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Derived products flow chart
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Cloud/precip cross section
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11 micron imagery T(11u) best detects mid-high level clouds
Cloud Clearing Step Cloud Building Step Iterative Adjustment Step Forward model converts cloud-sounding to T(11u) estimate Constrained 1DVAR iteration fits cloud layers to observed T(11u)
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Visible Satellite Improving visible with terrain albedo database
Cloud-clearing (done with current analysis) Cloud-building (now being tested) Accurate sfc albedo can work with VIS + 11 micron cloud-tops Visible cloud fraction can be used to correct apparent brightness temperature to yield improved cloud-top temperature
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3.9 micron imagery T(3.9u) – T(11u) detects stratus at night
Currently used with 11u cloud-tops for cloud building Testing underway for cloud-clearing Additional criteria include T(11u) and land fraction T(3.9u) – T(11u) detects clouds in the daytime? Visible may be similar in cloud masking properties Visible may be easier for obtaining a cloud fraction Cloud Phase? Could work using T(3.9u) – T(11u) at night Cloud-top phase needs blending throughout LWC/ICE column
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Cloud type diagnosis Cloud type is derived as a function of temperature and stability
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Surface Precipitation Accumulation
Algorithm similar to NEXRAD PPS, but runs in Cartesian space Rain / Liquid Equivalent Z = 200 R ^ 1.6 Snow case: use rain/snow ratio dependent on column maximum temperature Checks on Z and T could be added to reduce bright band effect
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Cloud/precip cross section
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Storm-Total Precipitation
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Cloud/Satellite Analysis Topics
11 micron IR 3.9 micron data Improving visible with terrain albedo database CO2-Slicing method (Cloud-top pressure)
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Visible Satellite Impact
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CO2 Slicing Method (cloud-top P)
Subset of NESDIS Cloud-Top Pressure data CO2 measurements add value 11u measurements (0 or 1 cloud fraction) redundant with imagery? Imagery has better spatial and temporal resolution? Treat as a “cloud sounding” similar to METARs and PIREPs
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Selected references Albers, S., 1995: The LAPS wind analysis. Wea. and Forecasting, 10, Albers, S., J. McGinley, D. Birkenheuer, and J. Smart, 1996: The Local Analysis and prediction System (LAPS): Analyses of clouds, precipitation and temperature. Wea. and Forecasting, 11, Birkenheuer, D., B.L. Shaw, S. Albers, E. Szoke, 2001: Evaluation of local-scale forecasts for severe weather of July 20, Preprints, 14th Conf on Numerical Wea. Prediction, Ft. Lauderdale, FL, Amer. Meteor. Soc. Cram, J.M.,Albers, S., and D. Devenyi, 1996: Application of a Two-Dimensional Variational Scheme to a Meso-beta scale wind analysis. Preprints, 15th Conf on Wea. Analysis and Forecasting, Norfolk, VA, Amer. Meteor. Soc. McGinley, J., S. Albers, D. Birkenheuer, B. Shaw, and P. Schultz, 2000: The LAPS water in all phases analysis: the approach and impacts on numerical prediction. Presented at the 5th International Symposium on Tropospheric Profiling, Adelaide, Australia. Schultz, P. and S. Albers, 2001: The use of three-dimensional analyses of cloud attributes for diabatic initialization of mesoscale models. Preprints, 14th Conf on Numerical Wea. Prediction, Ft. Lauderdale, FL, Amer. Meteor. Soc.
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