High Frequency Weather Forecasts

Last updated: Sat, Dec 16, 12:00:00 UT


Ronald J Maddalena
National Radio Astronomy Observatory
Green Bank, WV

All High-Frequency Overview Plots

The following overview plots show various forecasted quantities that users and schedulers of the GBT might be interested in seeing. The plotted quantities are determined from the forecasts that are described at my "High Frequency Weather Forecasts" pages and the algorithms that make up the GBT's Dynamical Scheduling System.
DSS Relative Efficiencies with Limits (L*eta/eta_min)Mustang Relative Efficiencies with Limits (L*eta/eta_min)
Key1 Explanation: The total score by which the DSS judges which projects will make the most efficient use of telescope time.

DSS Efficiencies without Limits (eta)Mustang Efficiencies without Limits (eta)
Key2 Explanation: Shows observing efficiency (Effs = EffAtm*EffTrack*EffSurf) without applying the DSS judgments for both the frequency-dependent stringency (EffMin) and the limits of when a project will become futile (LimitEff and LimitTrack).

DSS Efficiencies from Atmospheric Opacities (eta_atm)Mustang Efficiencies from Atmospheric Opacities (eta_atm)
Key2 Explanation: Shows the degradation in the the part of efficiency that arises from the atmosphere, relative to the best possible conditions for Green Bank.

DSS Efficiencies from Tracking Errors (eta_tr)Mustang Efficiencies from Tracking Errors (eta_tr)
Key2 Explanation: Shows the degradation in the the part of efficiency that arises from tracking and pointing errors due to winds and due to poorer telescope pointing performance during daytime observing, relative to nighttime observing.

DSS Efficiencies from Surface Errors (eta_surf)Mustang Efficiencies from Surface Errors (eta_surf)
Key2 Explanation: Shows the degradation in the the part of efficiency that arises from surface errors due to daytime observing, relative to nighttime observing.

DSS Minimum Relative Efficiencies (eta_min)Mustang Minimum Relative Efficiencies (eta_min)
Key2 Explanation: Indicates the minimum observing efficiency (Effs) for which the DSS judges that the science for a project will become futile.

DSS Limits on Relative Efficiency (L_effic)Mustang Limits on Relative Efficiency (L_effic)
Key2 Explanation: Indicates the penalty a project incurs for having an efficiency (Effs) below EffMin.

DSS Limits on Tracking Efficiency (L_track)Mustang Limits on Tracking Efficiency (L_track)
Key2 Explanation: Depicts a boolean that indicates when the estimated tracking and pointing errors will be large enough that the DSS judges that the science for a project will be futile.

Overview for Cloud Coverage and Conditions Unsuitable for Continuum Observing
Explanation: Shows the criteria for continuum observations, which have an additional scoring factors based upon cloud coverage, the atmospheric contributions to system temperature, and the IR irradiance from the sky.

Various colors codes depict different aspects of cloud coverage and other criteria for scheduling continuum projects.  In short, the times when conditions are best for continuum observing are those where blue extends from the top to the bottom of the figure.  Any shade of white, cyan, or magenta indicate less than perfect continuum conditions.
Key2


Dark Magenta: Unsuitable for Mustang (Daytime or high winds)
Medium Magenta: Unsuitable for Mustang (Atmos Tsys > 50 K)
Light Magenta: Suitable for some Mustang (Atmos Tsys is 35-50 K )
Cyan Unsuitable for all others systems (LWd > 300 W/m2)


REST & Winds
RESTs Good Winds Usable Winds Winds Too High
< 1.41
< 2 at 22 GHz
< 2, all but 22 GHz
>= 2
Explanation:
  • Plot provided mostly for historical purposes
  • The suggested wind limits use the PTCS recommendations for good (<5% gain fluctuations) or usable (<10% gain fluctuations) conditions or the telescope's stow wind speeds. 
  • The suggested RESTs limit for most frequencies is 1.41, which implies one will need twice the integration time as would be needed on the best of days.
  • REST>2 indicates needing more than 4x as much integration and are usually not recommended.
  • The suggested RESTs limits for 22 GHz is 2 since so little good weather is available at this frequency.