Post on 03-Jan-2016
description
UMBC PBL Height Study
Chris Wilson, Ruben Delgado, W. Wallace McMillan, Ray Hoff
Overview
• Description of the ProblemBoundary layer depth!
• Instruments and measurement techniques(LIDAR, BBAERI)
• Preliminary results
The diurnal evolution of the atmospheric boundary layer over land (from Wyngaard, 1992)
BBAERI vs. ELF
Expected collapse of PBL after sunset seen by both instruments
B.L. top
Residual Layer
B.L. TopB.L. Top
AERI• Atmospheric Emitted Radiance
Interferometer
• Measures downwelling IR radiation spectra (3 – 18 μm) passively
• 1 cm -1 Resolution
H2O
H2O
CO2
O3
CO2
CO
AERI T/q
Statistical regression (training sondes)
Spectra, surface, RUC
“Onion Peel”
Physical Retrieval
T(p), q(p), theta(p), RH(p)
* From Smith ET AL. 1999
* *
Covariance Wavelet TechniqueCovariance Wavelet Technique
W a ba
f z hz b
adz
zb
zt( , ) ( ) ( )
1
Covariance transform defined by Gamage and Hagelberg (1993):
• zt and zb are the top and bottom altitudes in the lidar backscatter profile• f(z)is the lidar backscatter profile as a function of altitude, z• a-1 is the normalization factor
Haar function
• z=vertical distance in this application• a=spatial extent dilation of the function• b=center of Haar function- translation of the function
PBL Determination:
•Compute convolution of the backscatter profile, f(z), and the Haar function.
•Taking a lidar backscattering profile, calculate a local minimum in W (a,b) using a scale of a located at z = b
•This process is repeated for all individual lidar backscatter profiles to create a time series of boundary locations.
The key of the wavelet analysis is the selection of an appropriatedilation (vertical scale).
BBAERI Height Methods
• Gradient in Virtual Potential Temperature
• Temperature Inversion
• Parcel Method
• Minimum gradient in q (water vapor mixing ratio)
Inversion
Parcel Method
VPT
Gradient
Minimum in gradient of q
Hei
ght
(met
ers)
Time (GMT)
Hei
ght
(met
ers)
Time (GMT)
Final Remarks
• Sonde measurements are needed
• Many more days are needed to create robust statistics
• BBAERI water vapor product may be to coarse to accurately measure PBL height
Hei
ght
(met
ers)
Time (GMT)