1 / 44

The Kain-Fritsch Convective Scheme

Outline. KF Deep convection Basic concepts/proceduresComparison of Eta, EtaKF forecastsUpdraft mass flux: a unique output field that is useful for forecasting and provides insight into the scheme's basic closure assumption. KF Shallow convectionBasic concepts/proceduresComparison of Eta, EtaK

artaxiad
Télécharger la présentation

The Kain-Fritsch Convective Scheme

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. The Kain-Fritsch Convective Scheme Jack Kain and Mike Baldwin 2006 Unidata Workshop

    2. Outline KF Deep convection Basic concepts/procedures Comparison of Eta, EtaKF forecasts Updraft mass flux: a unique output field that is useful for forecasting and provides insight into the scheme’s basic closure assumption. KF Shallow convection Basic concepts/procedures Comparison of Eta, EtaKF forecasts Real world impact

    3. What are the fundamental similarities/ differences between BMJ and KF?

    4. KF scheme basic procedures…

    5. Conceptual diagram of KF deep convection: a “Mass-flux” parameterization

    6. KF adjustment profiles

    7. Compare performance of BMJ and KF schemes First, consider an environment in which the BMJ scheme produces a better forecast…

    8. Consider a forward propagating MCS from May 31, 2000…

    9. 31 MAY 2000 ~1500-1900 UTC BREF

    10. Consider a location just north of the boundary, behind leading convective line, 15h Eta forecast valid 15 UTC 31 May 2000…

    11. Look at one hour sounding changes from the operational Eta…BMJ scheme imposes strong heating aloft, cooling below; note strong upward motion aloft, subsidence in cooling layer

    12. By feeding back a similar heating/cooling profile over a large area, BMJ scheme induces a mesoscale downdraft and enhanced upward motion at the leading edge of the “MCS”

    13. In contrast, Etakf run has relatively limited convective activity, much less coherent structure:

    15. How about convective initiation in a “loaded gun” environment?

    17. EtaKF forecast sounding at time of KF param initiation

    19. EtaKF 3h precipitation forecast…

    20. Local Storm Reports 9 May 2001

    21. What is the Updraft Mass Flux (UMF*)?

    22. How is UMF* determined?

    25. How about shallow (non-precipitating) convection?

    26. KF scheme: Checking for the possibility of deep (precipitating) convection…can a parcel reach its LFC and form a deep cloud?

    27. KF scheme: Can a parcel reach its LFC and form a deep (precipitating) cloud?

    28. KF scheme: Can a parcel reach its LFC and form a deep (precipitating) cloud?

    29. KF scheme: Can a parcel reach its LFC and form a deep (precipitating) cloud?

    30. KF scheme: Can a parcel reach its LFC and form a deep (precipitating) cloud?

    31. KF scheme: determining shallow-convection adjustment profiles

    32. KF shallow convection parameterization…requires many assumptions

    33. …It’s cloud illusions that I recall I really don’t know clouds at all…

    34. KF scheme adjustment profiles

    35. Remember the Eta (BMJ) biases that Mike showed?

    36. How about same 12h forecast using KF shallow convection instead of BMJ (EtaKF)?

    37. 24 h Eta/EtaKF soundings vs. DFW raob

    38. Shallow convection mean moisture tendencies 21h fcst

    39. Consider the impact of parameterized shallow convection: 12 h forecasts for BHM valid 00 UTC 12 May 2000

    40. 48 h Eta CAPE forecast

    43. SPC forecasters identified the characteristic bias of the Eta model, boldly suggested the 48 h forecast sounding was “in error”

    44. 48 h later: SHV observed sounding…

More Related