Hi!
Based on the input I have received in this list, I have done the following for
my own project. Any comments are very welcome:
A new standard name modifier: confidence, used like this:
float wind_speed_confidence(time, latitude, longitude) ;
wind_speed_confidence:units = "1" ;
wind_speed_confidence:standard_name = "wind_speed confidence" ;
A dimension (and variable) for specifying percentiles:
float percentile(percentile) ;
percentile:units = "1" ;
percentile:standard_name = "cumulative_distribution_function" ;
float air_temperature_percentiles(time, percentile, latitude,
longitude) ;
air_temperature_percentiles:units = "K" ;
air_temperature_percentiles:standard_name = "air_temperature" ;
...an alternative for percentile could be
cumulative_distribution_function_over_realization.
Then, there is the problem of certainty that a temperature will be within a
given range. I have tried the following, using a new standard_name
(interval_of_air_temperature), along with the previously mentioned confidence
modifier:
float confidence_interval(confidence_interval) ;
confidence_interval:units = "K" ;
confidence_interval:standard_name =
"interval_of_air_temperature" ;
confidence_interval:long_name = "air_temperature offset from a
given value (in either direction)" ;
float air_temperature_confidence(time, confidence_interval, latitude,
longitude) ;
air_temperature_confidence:units = "1" ;
air_temperature_confidence:standard_name = "air_temperature
confidence" ;
air_temperature_confidence:long_name = "probabilty of
air_temperature within +/- confidence_interval" ;
This allows for several confidence intervals.
Also, which I did not mention in the previous emails, I also wanted to express
the probability of at least x mm of precipitation. This I have tried to solve
by adding another standard_name (limit_of_precipitation_amount):
float precipitation_limit(precipitation_limit) ;
precipitation_limit:units = "kg m2" ;
precipitation_limit:standard_name =
"limit_of_precipitation_amount" ;
float precipitation_limit_confidence(time, precipitation_limit,
latitude, longitude) ;
precipitation_limit_confidence:units = "1" ;
precipitation_limit_confidence:standard_name =
"precipitation_amount confidence" ;
precipitation_limit_confidence:long_name = "probability of
precipitation_amount above precipitation_limit" ;
When working with this, I found that expressing percentiles and probabilities
as dimensions, instead of attributes, made the relationship between them more
intuitive. This also made using ncview to compare various percentiles for the
same variable very easy, in case you're into that sort if things..
-- Vegard
----- Original Message -----
Fra: "Vegard Bønes" <[email protected]>
Til: [email protected]
Sendt: 15. november 2011 10:10:02
Emne: [CF-metadata] standards for probabilities
Hi!
I am trying to create a document containing various probability values for
weather forecasts. But I do have some problems finding out how to express what
I want to say using the cf metadata standard.
I want to express such things as "25th percentile precipitation amount" (based
on ensemble data), and probability that air temperature will be within 2.5
degrees of the forecast. How should I do this?
For percentiles, may I do something like this?
float precipitation_25(time, x, y) ;
precipitation_25:standard_name = "precipitation_amount" ;
precipitation_25:long_name = "precipitation_amount 25th percentile" ;
...
Also, as far as I can tell, there is no standardized names like
probability_of_x or probability_of_x_within_y. How can I express this?
-- Vegard
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