BADC Trajectories - PUMA
Plot PUMA trajectories
A set of trajectories are being run at the BADC for the PUMA
campaign. These trajectories are run from ECMWF analyses and
forecasts that have been gridded to a 2.5x2.5 degree grid. The ECMWF
data used is the model level data and so is on 50 hybrid
sigma-pressure levels.
Five day Back trajectories are run for four sites, and at 11 levels. The
sites are the observation sites used during the campaign (see Table 1). The
levels are the lowest 11 standard radiosonde levels (1000hPa, 925hPa, 850hPa,
700hPa, 500hPa, 400hPa, 300hPa, 250hPa, 200hPa, 150hPa, 100hPa).
On each day during the campaign
a number of forecast back trajectories will be calculated with
different start times.
The start times for the forecasts will be 12.00 and 18.00 on that day,
0.00, 6.00, 12.00, 18.00 on the next day and the day after that,
and 12.00 on the following three days. So on the 4th June 1999 forecast
trajectories will be run for the following
| Day 0 | 1999060412, 1999060418 |
| Day 1 | 1999060500, 1999060506, 1999060512, 1999060518 |
| Day 2 | 1999060600, 1999060606, 1999060612, 1999060618 |
| Day 3 | 1999060712 |
| Day 4 | 1999060812 |
| Day 5 | 1999060912 |
The winds used in calculating the forecast trajectories will be
forecast winds for times after 12.00 the previous day and analyses for
times before that. So for the 1999060412 trajectory forecast made on
the 4th of June the winds will be analysed winds for the four days
before 12.00 on the 3rd and forecast winds, with the ECMWF forecast
made from 12.00 on the 3rd, for the day between 1999060312 and
1999060412.
In addition to the forecast back trajectories and archive of 5 day
back trajectories calculated using analyses will be made. This
archive will contain trajectories starting at 0.00, 6.00, 12.00, and 18.00
for each day of the campaign.
The trajectories at each station at each end point in time are in
separate files. The files are labeled by a station code (see Table 1)
and the end point date in the format yyyymmddhh. At each end time all
stations are placed in the same directory, which is labeled by the
date in the same format. The output file format is netCDF, and the
details of the format are described
elsewhere.
Table 1. Back trajectory end-points for PUMA
| Station name | Code | Grid
Reference | Latitutde | Longitude |
|---|
| Halfpenny Green Airport | hp |
SO 823 907 | 52.514 | -2.261 |
| Lucy's Farm | lf |
SP 164 629 | 52.264 | -1.760 |
| Packington Farm | pf |
SK 148 058 | 52.649 | -1.781 |
| Withybrook Equestrian Centre | we |
SP 446 853 | 52.463 | -1.343 |
Additional Notes
The PUMA trajectories have been rerun after discovering a
bug in
the trajectory model. There are some changes in the details of
the trajectories. If you notice any big changes in any of the parcel
paths then please contact us.
The trajectories that are currently available through the Precalculated Trajectory page are the revised trajectories. The
old trajectories are
still available if needed for comparisons or checks.
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