ASP lab response case: 23 June 2008

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Contents

Introduction

Several data fields from a CSU-CHILL RHI scan through a thunderstorm are shown below. A few questions are listed below the polarimetric data field plots. Please submit your answers as an e-mail with a subject of "23 June 2008" sent to:

asp@chill.colostate.edu

NOTE: You may complete your responses and send the e-mail outside of the basic polarization lab period.

For general reference, here is the basic reflectivity (Zh) data from the storm: 23jun2008 rhi dbz.png

Differential Reflectivity (Zdr)

23jun2008 zdr th anot.png 1.) Based on the reflectivity and differential reflectivity data, what is the dominant form of precipitation at the points marked in the Zdr plot?

1a:

1b:

1c:

2.) Consider the vertical profile of Zdr along the vertical line marked as point 2 in the Zdr image. What is the probable cause of the locally positive Zdr layer located near the 2 km AGL height line?

2:

Differential Propagation Phase (Phidp)

23jun2008 phi 5km.png

3a.) Over what range interval does the greatest phidp change take place?

3a:

3b.) The presence of what hydrometeor type is causing this increasing lag between the H and V return signals?

3b:

Co-polar Correlation between the H and V Returned Signals (RhoHV)

23jun2008 rhi rho anot.png

The correlation field has a local relative minimum of ~0.95 at the point marked.

4. What precpitation composition is probably responsible for this?

4:

Linear Depolarization Ratio (LDR)

23jun2008 ldr th anot.png 5a: A local maximum (~-23 dB) in linear depolarization is seen at point 5a. What hydrometeor type is responsible for this?

5a:

5b: There is also a general tendency for the LDR values to become large in the more didtant and/or weaker reflectivity portions of the echo. (Point 5b for example). Why should the LDR values tend to increase in these areas?

5b:


Remember: Submit your responses to questions 1 - 5b to asp@chill.colostate.edu with the subject line "23 June 2008".