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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Don On 5/18/15 12:25 PM, Unidata THREDDS Support wrote:
Greetings IDV users, As thredds.ucar.edu is switched to the 4.6 version of the THREDDS Data Server (TDS), you may notice the same names of variables have changed. Specifically, you will likely encounter the case where Mixed Interval variable have been renamed to indicate that they are no longer mixed, but rather fixed interval variables. As an example, if we consider the Rapid Refresh Model, the following old variable name: Convective_precipitation_surface_Mixed_intervals_Accumulation has been changed to: Convective_precipitation_surface_1_Hour_Accumulation Why did this happen? The THREDDS group has looked over all cases of Mixed Interval Variables in the data we serve out and we noticed that, in some cases, mixed intervals were not needed, and we we able to reduce these to single interval variables. Again, considering the Convective Precip variable from the Rapid Refresh, the old variable: Convective_precipitation_surface_Mixed_intervals_Accumulation actually contained two types of intervals over which the accumulation occurred (thus the "mixed interval" in the name). One interval was the 1 hour interval: accumulation over forecast hours 0-1, 1-2, 2-3, 3-4., etc. The second interval contained a total run accumulation: accumulation over forecast hours 0-1, 0-2, 0-3, 0-4, etc. When served as a mixed interval, the data would look something like: accumulation over forecast hours 0-1, 0-1, 1-2, 0-2, 2-3, 0-3... The end result is that, when displayed in the IDV, the precip field would appear to "jump" around in magnitude when animated. However, given the simplicity of how these intervals were actually "mixed", we were able to, on the server side, remove the total accumulation over the run portion of the grids while only serving the 1 hour accumulation grids. Since the total run accumulation can be computed from the 1 hour interval accumulations, this seems like the reasonable thing to do. Depending on the model, the mixed interval grid may be rename as a 1_hour_Accumulation, or a 3_hour_Accumulation (other interval lengths will be possible in the future, I'm sure). That means replacing all of the Mixed Interval Variable names with a 1 hour Accumulation variable name is not a safe option. After much discussion with the IDV group over the past year+, we've agreed that in these cases (where data fundamentally change meaning), it's best to allow users of the IDV to see that these changes have occurred. We are not big fans of silently changing the meaning of the variables. Further, we aren't sure how aware users are of the complexity of these mixed interval data, so this will bring these issues to the forefront. For users of IDV bundles, this means you will need to re-save your bundle after being prompted to select a new variable. We hope you find these reduced mixed interval variables are more useful, and please know that we are working on a solution for the more complex types of mixed intervals (for example, every mixed interval in the GFS output). Because these more complex mixed interval variables still show up as Mixed Interval variables (and are very nuanced), be very cautious when using them as they are likely NOT what you think or hope they might be. In the coming weeks we will be doing a series of blog posts explaining in detail how these mixed interval grids come about, and why there are cases where the reduction of a mixed interval variable is not as simple as the case above. Here is a list of the datasets, and associated variables, where these changes occur: Rapid Refresh collections (for old name, replace 1_Hour with Mixed_intervals): Convective_precipitation_surface_1_Hour_Accumulation Large-scale_precipitation_non-convective_surface_1_Hour_Accumulation NAM 12km NOAAPORT (for old name, replace 3_Hour with Mixed_intervals): Convective_precipitation_surface_3_Hour_Accumulation Percent_of_Frozen_Precipitation_surface_3_Hour_Accumulation Probability_of_0p01_inch_of_precipitation_POP_surface_3_Hour_Accumulation Probability_of_Freezing_Precipitation_surface_3_Hour_Accumulation Thunderstorm_probability_surface_3_Hour_Accumulation Total_precipitation_surface_3_Hour_Accumulation NAM 12km CONDUIT (for old name, replace 3_Hour with Mixed_intervals): Baseflow-Groundwater_Runoff_surface_3_Hour_Accumulation Convective_precipitation_surface_3_Hour_Accumulation Deep_Convective_Heating_Rate_entire_atmosphere_single_layer_3_Hour_Average Downward_Short-Wave_Radiation_Flux_surface_3_Hour_Average Large_Scale_Condensate_Heating_Rate_entire_atmosphere_single_layer_3_Hour_Average Snow_melt_surface_3_Hour_Accumulation Storm_Surface_Runoff_surface_3_Hour_Accumulation Total_precipitation_surface_3_Hour_Accumulation Water_equivalent_of_accumulated_snow_depth_surface_3_Hour_Accumulation NAM 20km NOAAPORT (for old name, replace 3_Hour with Mixed_intervals): Convective_precipitation_surface_3_Hour_Accumulation Percent_of_frozen_precipitation_surface_3_Hour_Accumulation Probability_of_freezing_precipitation_surface_3_Hour_Accumulation Probability_of_precipitation_surface_3_Hour_Accumulation Snow_depth_surface_3_Hour_Accumulation Thunderstorm_probability_surface_3_Hour_Accumulation Total_precipitation_surface_3_Hour_Accumulation NAM 40km CONDUIT (for old name, replace 3_Hour with Mixed_intervals): Baseflow-Groundwater_Runoff_surface_3_Hour_Accumulation Convective_precipitation_surface_3_Hour_Accumulation Downward_Long-Wave_Radp_Flux_surface_3_Hour_Average Downward_Short-Wave_Radiation_Flux_surface_3_Hour_Average Evaporation_surface_3_Hour_Accumulation Ground_Heat_Flux_surface_3_Hour_Average Large-scale_precipitation_non-convective_surface_3_Hour_Accumulation Latent_heat_net_flux_surface_3_Hour_Average Potential_Evaporation_surface_3_Hour_Accumulation Sensible_heat_net_flux_surface_3_Hour_Average Snow_Phase_Change_Heat_Flux_surface_3_Hour_Average Snow_melt_surface_3_Hour_Accumulation Storm_Surface_Runoff_surface_3_Hour_Accumulation Total_cloud_cover_entire_atmosphere_single_layer_3_Hour_Average Total_precipitation_surface_3_Hour_Accumulation Upward_Long-Wave_Radp_Flux_atmosphere_top_3_Hour_Average Upward_Long-Wave_Radp_Flux_surface_3_Hour_Average Upward_Short-Wave_Radiation_Flux_atmosphere_top_3_Hour_Average Upward_Short-Wave_Radiation_Flux_surface_3_Hour_Average Water_equivalent_of_accumulated_snow_depth_surface_3_Hour_Accumulation Thank you, The THREDDS Development Team _______________________________________________ idvusers mailing list idvusers@xxxxxxxxxxxxxxxx For list information, to unsubscribe, visit: http://www.unidata.ucar.edu/mailing_lists/
-- Don Murray NOAA/ESRL/PSD and CU-CIRES 303-497-3596 http://www.esrl.noaa.gov/psd/people/don.murray/
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