NIM/MPL/M1 - False Positive Cloud Base Height Values During Solar Noon

As the laser ages, the output reduces.  This lowers the signal to noise ratio. The lower 
signal to noise ratio interferes with the cloud base height algorithm to correctly 
determine if a cloud is actually present. During solar noon the signal to noise ratio is the 
lowest. This condition results in many false positive values. The values start at a high 
altitude and progressively get lower as the sun gets to zenith. The trend reverses as the 
sun passes. The pattern in the data resembles a ?V? shape starting 2 hours before solar 
noon to 2 hour past. A low incident of false positive values exists from 20051227. However, 
the condition becomes prominent on 20060303 - 20060420. The cloud base calibration table 
was modified to compensate for the lower signal to noise levels. 

Note: If a cloud is actually present, the cloud base algorithm will determine the height 
and report correctly. The false positive values are only a concern during cloud free 
conditions.

• Preliminary cloud base height(preliminary_cbh)

• null(Raw data stream - documentation not supported)

NIM/TSI/M1 - Reprocess: Data processing problem

Due to the high aerosol conditions at Niamey, the TSI appeared to be beyond the limits of 
processing the color JPEG image into cloud fraction values. Several attempts to adjust 
the sky filter values used to process the images did not yielded the desired results. The 
processed images indicate an opaque sky cover, even in the absence of clouds.

The problem was corrected by removing the neutral density filter from the lens and 
re-adjusting the sky filter values.

The data can be reprocessed.

• PNG data stream - documentation not supported(png)

• Pixel count: number total thin(count.thin)
• Pixel count: number thin in horizon area(region.horizon.count.thin)
• Pixel count: number total opaque(count.opaque)
• Pixel count: number opaque in horizon area(region.horizon.count.opaque)
• Pixel count: number opaque in zenith circle(region.zenith.count.opaque)
• Sunshine meter(sunny)
• Pixel count: number opaque in sun circle(region.sun.count.opaque)
• Pixel count: number thin in sun circle(region.sun.count.thin)
• Percent opaque cloud(percent.opaque)
• Percentage thin cloud(percent.thin)
• Pixel count: number thin in zenith circle(region.zenith.count.thin)

NIM/TSI/M1 - Shadowband glare

When the neutral density filter was removed from the lens, the reflection of the sun from 
the smooth shadowband strip became much brighter causing a glare in the image on clear 
days. To minimize this reflection, a rough surface (the "fuzzy" side of an adhesive velco 
strip) was placed along the length of the shadowband.

• Relative \'strength\' of direct sun(sun.strength)
• Pixel count: number total in sun circle(region.sun.count)
• Sunshine meter(sunny)