Re: Ascii data with date and time in the file

[Mary Quinton <quintonmary@xxxxxxxxx>]

Hi Ben,
Here's a FERRET FAQ that tells how to set up
a time axis from ascii time info:
http://www.ferret.noaa.gov/Ferret/FAQ/axes_and_data/time_axis_from_variables.html

I think that then your data will look like a 
continuous series on an irregular axis, with
longer intervals where the missing times are. Maybe 
you can use DEFINE AXIS to set up a regular time 
axis and regrid your data to that.

Mary

--- Ben Burford <benb@restec.or.jp> wrote:
> Hello All,
> 
> I'm new to Ferret and I have some slightly
> complicated data to work with.  I
>  have station data in ascii where the date and time
> (year, month, day, hour,
>  minute) for each set of readings is in the file. 
> The date/time and data ar
> e recorded at a 30 minute interval.  However, one of
> the most important feat
> ures of this data is that the time series is not
> continuous - the instrument
>  may drop out and back in randomly.  So, there may
> be one, or any number of 
> times missing in the date/time sequence.  
> 
> For simplicity I will focus on one variable
> (air_temperature).  The data in 
> the file looks like this:
> 
> 2002/10/01 00:30, -0.1
> 2002/10/01 01:00, 0.98
> 2002/10/01 01:30, 2.66
> 2002/10/01 02:00, 4.12
> 2002/10/01 02:30, 6.23
> etc.
> 
> 
> Information about the data from the DODS server:
> 
> date_year, date_month, date_day, date_hour,
> date_min, . . . air_temperature,
>  . . . 
> 
> Int32 date_year;
> Int32 date_month;
> Int32 date_day;
> Int32 date_hour;
> Int32 date_min;
> Float32 air_temperature;
> 
> 
> One of the nice features of the server is that there
> are functions to allow 
> me various ways to access the date/time information:
> 
> 1. Separate - year, month, day, hour, minute values:
> 
> 2002, 10, 1, 0, 30,
> 2002, 10, 1, 1, 0,
> 2002, 10, 1, 1, 30,
> 2002, 10, 1, 2, 0,
> 2002, 10, 1, 2, 30,
> etc.
> 
> 
> 2. A date/time string
> 
> "2002/10/1:00:30:00 GMT"
> "2002/10/1:01:00:00 GMT"
> "2002/10/1:01:30:00 GMT"
> "2002/10/1:02:00:00 GMT"
> "2002/10/1:02:30:00 GMT"
> etc.
> 
> 
> 3. A decimal year where the date and time are used
> to calculate a floating-p
> oint "fractional year":
> 
> "2002.7480022831"
> "2002.7480593607"
> "2002.7481164384"
> "2002.748173516"
> "2003.2437214612"
> "2003.2437785388"
> "2003.2438356164"
> 
> 
> So, can you tell me how to plot this data with
> Ferret (knowing that the date
> /time is not continuous) plotting air_temperature
> against time?
> 
> Thank you,
> 
> Ben
> 
> 
> 
> 



		
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