MIDC: Cylinder (Shades) Plots

Interpreting Cylinder Plots

SERI_QC Flags:

DQMS assigns a 2-digit data quality flag to each 1-minute data value for global (broadband hemispheric downwelling shortwave), direct normal, and diffuse horizontal irradiance components. This graphical portion of the report shows the worst offending flag value (worst flag from among all irradiance components at that point) as a gray-scale; white to light-gray is good data quality; dark gray to black is poor or missing data quality. K-space Cylinders:

DQMS converts the 1-minute irradiance data from units of Watts per square meter to fractional values based on the corresponding extraterrestrial value for the time and site location of the measurement. High irradiance levels translate to lighter shades and low irradiance levels are darker shades (black is night-time or heavy overcast when the pyrheliometer measures at or near zero irradiance).

Irradiance Element	Symbol	K-Space Conversion
Global Horizontal	Kt	Global / Isc * ECF * Cos(Z)
Direct Normal	Kn	Direct / Isc * ECF
Diffuse Horizontal	Kd	Diffuse / Isc * ECF * Cos(Z)

^-2

Summary Statistics:

High-quality (data judged to be within 5% of true values)
Questionable data quality (greater than 10% uncertainties)
Above or below empirical limits (time of day dependent; e.g., -1.23 for DHI is below empirical limits at 12:00 PM, or nighttime irradiances less than -10 Wm^-2)
Data seem outside quality limits, but collectively agree with internal constraints (global = direct normal * Cos(Z) + diffuse).

[NREL] [MIDC]