mixing height (mh) national weather association’s 40th annual meeting 2015 10/20/20152 the height...
TRANSCRIPT
Using Ceilometer Data to Compare Mixing Height Calculations
Mark Loeffelbein1
Randy Graham2
1NWS Western Region HQ2NWS WFO Salt Lake City, UT
National Weather Association’s 40th Annual Meeting 2015
2
Mixing Height (MH)
10/20/2015
• The height above the surface that aerosols vertically disperse. Also referred to as boundary layer depth.
• Important in fire weather as it is used to predict how well smoke from a fire will ventilate.
• Important to air pollution by providing the depth pollutants will disperse to.
National Weather Association’s 40th Annual Meeting 2015
3
Motivation
10/20/2015
• R20 – Research from Desert Research Institute shows that there are likely more accurate methods to calculate mixing height.
• Currently no standard method to calculate mixing height.
• No verification data readily available to verify mixing height.
• Highlight a potential new dataset.
National Weather Association’s 40th Annual Meeting 2015
4
Methods of Calculating MH
10/20/2015
• Holzworth Method - (Parcel Method).• WR Parcel Method – Same as Holzworth, but 2
degrees added to surface temperature.• Stull Method – Similar to Holzworth but uses
Virtual Potential Temperature.• Bulk Richardson Number – Uses a combination of
convective/shear turbulence
Utilized data from NCEI Integrated Global Radiosonde Archive for upper air analysis.
National Weather Association’s 40th Annual Meeting 2015
510/20/2015
National Weather Association’s 40th Annual Meeting 2015
610/20/2015
Holzworth
StullWR Holzworth
Richardson
National Weather Association’s 40th Annual Meeting 2015
7
Mesowest Above Surface Networks
10/20/2015
University of Utah&
Mesowest
National Weather Association’s 40th Annual Meeting 2015
8
Verification Method
10/20/2015
• Ceilometer data from Viasala CL31. Persistent Cold-Air Pool Study (PCAPS) and University of Utah.
• Multiple methods for calculation of mixing height from data.
• Used the Idealized Profile method for this study.
• Ceilometer not co-located with upper air site.
National Weather Association’s 40th Annual Meeting 2015
9
Ceilometer Time/Height
10/20/2015
National Weather Association’s 40th Annual Meeting 2015
10
Ceilometer Time/Height
10/20/2015
Holzworth
Stull
WR Holzworth
Richardson
National Weather Association’s 40th Annual Meeting 2015
11
Ceilometer Time/Height
10/20/2015
HolzworthStull
WR Holzworth
Richardson
National Weather Association’s 40th Annual Meeting 2015
12
Verification
10/20/2015
Holzworth WR Holzworth
Stull Richardson
National Weather Association’s 40th Annual Meeting 2015
13
Verification (Spring)
10/20/2015
* Below 2000 m
National Weather Association’s 40th Annual Meeting 2015
14
Verification PCAPS (Winter)
10/20/2015
National Weather Association’s 40th Annual Meeting 2015
15
Verification (Year)
10/20/2015
* Below 2000 m
National Weather Association’s 40th Annual Meeting 2015
16
Verification (Year)
10/20/2015
* Below 2000 m
National Weather Association’s 40th Annual Meeting 2015
17
Summary
10/20/2015
• Initial verification shows there is significant uncertainty in the sounding approach compared to the ceilometer.
• Of the sounding approaches blending the methods seems to be the most skillful.
• Caveats– Dataset too small to be statistically significant.– Most useful method may be geographically dependent.– Ceilometer data is only useful if aerosols are present.– Verification method for calculating mixing height is not as
robust as one would hope for.• R20 – Apply method to models through SmartInits.
National Weather Association’s 40th Annual Meeting 2015
18
Acknowledgements
10/20/2015
John Horel – University of Utah
Joseph Young – University of Utah/Mesowest
Persistent Cold Air Pool Study (PCAPS)