1. HARGLO-2 Meteorological Context
David O. Miller – SSAI/NASA GSFC
I am going to discuss the meteorological conditions during HARGLO-2. HARGLO-2 was held at the NASA/Wallops Flight Facility in Virginia which is located here (point to location).

2. Outline Range of conditions Data timeline Daily overview
I’m going to begin by covering the range of conditions that the instruments under which the instruments operate the best. Then I’ll show a data timeline for HARGLO-2 used to illustrate the overlap of the instruments. Then I’ll conclude with an overview of the general weather conditions for the six days that we recorded data.

3. GLOW: Performance degrades with very dense aerosol and clouds.
One of the goals of HARGLO-2 is to explore the range of conditions under which HARLIE and GLOW can successfully measure the wind.
HARLIE: The accuracy of derived wind vectors increases with greater amounts of non-homogeneous aerosol.
GLOW: Performance degrades with very dense aerosol and clouds.
SPANDAR: needs clouds and/or precipitation.
SkyCam: Visible aerosol and/or clouds are needed
One of the goals of HARGLO is to determine the range of meterological conditions that allow HARLIE and GLOW to successfully operate together. Clouds and aersols, or the lack thereof, is the primary factor.
A method of tracking aerosols is used to derive winds vectors from HARLIE data. Strong aerosol backscatter ‘helps’. Structure is needed however.
Glow measurement performance degrades with increasingly dense aerosol content.
SPANDAR, being an S-band radar, needs clouds and/or precipitation for accurate wind measurements.
The SkyCam is a standard video camera with a fisheye lens needing visible clouds to be useful. (daytime operation only).

4. HARGLO-2 Data Timeline
The upper portion of this slide shows a timeline of the data collected during HARGLO-2 and the lower portion is a time/altitude plot of HARLIE data.
I’ll focus on the timeline first. The timeline covers the six days that measurements were taken during HARGLO-2. Each of the rows represents an instrument with the vertical bars showing when the instrument was in operation.
The first row is the skycam, operating only during the daytime.
Next row represents the radiosondes. The blue bars represent the NWS sondes launched at 0 and 12Z and the orange bars represent the GPS sondes launched at 15 and 20Z.
The spandar was operation during normal working hours on the 15th, 16th, and the 19th.
This row represents the GLOW operation with the high and low energy modes denoted.
And the last row shows the HARLIE operation period. Harlie ran nearly continuously.
The image on the bottom is a time/altitude plot of HARLIE data covering the 15th throught the 20th up to an altitude of 20km. The image was created by averaging each rotation of HARLIE and plotting the data like it was a static system. The image has not been normalized in time so the bars caused by the inclusion of an etalon are visible. The bright features here (skyglow) are background from the sun. A weak cold front passed the site on the 17th and is visible here (point to wedge). The front was followed by stratocumulus that lasted nearly an entire day. The cirrus clouds are visible here and here. The cirrus on the 19th are in advance of the cold front that passed through on the last day of the campaign.
Another goal of the campaign was to test the ability of HARLIE to run continuously.

5. November 15, 2001
Both the 15th and 16th were relatively clear days. This was due to the high pressure system centered over kentucky.
Winds were from the south near the surface turning to the west with altitude with speeds from 5 m/s near the surface to around 30 m/s.

6. November 16, 2001
Both the 15th and 16th were relatively clear days. This was due to the high pressure system centered over kentucky.
Winds were 10 to 20 m/s and from the west-northwest at all levels.
The low presure centered over michigan will bring some of our most promising measurement conditions.

7. November 17, 2001
The weak cold front associated with the low now off nova scotia moved through around 5Z on the 17th. This front brought a mixture of clouds. The low overcast that follows the front persisted for the remainder of the day. The winds shifted to northerly after the front, with speeds around m/s.

8. November 18, 2001
The low cloud cover broke up early in the day leaving another clear day with some aerosol structure. Winds were around 5 m/s from the east near the surface veering to the west and increasing to m/s above 2 km.

9. November 19, 2001
Cirrus clouds move in ahead of an approaching cold front. Boundary-layer development clear on this day. The winds were from the south-southwest and around m/s at all levels.

10. November 20, 2001
Low-level clouds develop and cirrus thicken. Light precipitation aloft around 10Z. The measurements concluded around 12Z.