Meteorological analysis of CARIBIC

Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.


Introduction

This page gives access to meteorological information prepared by KNMI (Peter van Velthoven) for the CARIBIC project. The meteorological analysis of the CARIBIC measurement flights is based on ECMWF data with a resolution of 1x1 degree on ECMWF model levels.
Up to 13 September 2000 ECWMF first guess fields (6-hour forecasts) were used. First guess fields were somewhat smoother than analyses until then because ECMWF applied a 3-D var assimilation technique. After this ECMWF changed to 4-D var data assimilation and first guess fields were not available anymore. Most of the model data for flights thereafter are based on analyses. However, some data, e.g. the cloud parameters, are based alternatively on 6 hour forecasts (at 6 and 18 UT) and 12 hour forecasts (at 0 and 12 UT) because they are not analysed by ECMWF, only forecasted.
Precipitation always is a field accumulated over the 6 hours prior to the time indicated in the plot headers.
The ECMWF data are from the operational archive (OD), i.e. the ECMWF model version is varying in the course of time. Recently, also ECMWF re-analysis data (ERA40) have become available for the CARIBIC time frame. The differences between OD and ERA40 are small when analysing CARIBIC, except perhaps near the intertropical convergence zone in the tropics.
More information about the trajectories, the interpolation procedures and what is displayed in the plots can be found on the Plot explanation page.

Notes

  1. All plots are in gif- or png-format. Please contact Peter van Velthoven if you need postscript versions of the plots.
  2. There is a description of the trajectory file format for CARIBIC.
  3. There is an understood error in the plotted measured temperature of about 10 K for the four LTU July 2000 flights. See e.g. 11 July 2000. There is a corresponding error in the measured potential temperature. See e.g. 11 July 2000.
  4. Also for Lufthansa flights 112-149 there is an offset in the temperature (and potential temperature) measured on board the aircraft.
  5. For the Lufthanse WAS samples I calculated 15 additional trajectories in a cube centred around the sample in order to get an impression of uncertainty. These samples are taken within a minute so the trajectories for the samples themselves stick very close to each other. The additional trajectories end in the corners and the centre of 3 squares located at the average pressure of the sample, and at pressures of 97 and 103 percent of the average sample pressure. These trajectories are green, yellow and red respectively. The sides of the squares are 0.8 degrees in longitude and latitude.
  6. On 12 September 2006 the ECMWF model changed to a cycle where ice supersaturation is allowed (see Tompkins et al., QJRMS 133, 53-63 (2007)). Hence (interpolated) RH can reach values well above 100 percent.
  7. I redesigned the software (magics-->idl) and plot format (grib1-->netcdf) for flights from July 2013 onward. The reason is amongst others that grib2 cannot manipulate more than 99 model levels. ECMWF changed to 137 model levels on 25 June 2013. I cannot run the old grib1 software anymore because some libraries are not available for my current 64-bit linux work station. Some of the information in the plot explanation page still needs to be adapted.

What's new?

Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.

Lufthansa flights

Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.

Meteorological analysis of CARIBIC LTU flights (part 1 - the oldest)


Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.


Meteorological analysis of Caribic LTU flights (part 2):

See the plot description and flight summaries for interpretation of the plots (in progress).
Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.

Caribic meteorological data

Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.

Caribic links:

Index: Intro Notes What's new? Lufthansa flights LTU flights part 1 LTU flights part 2 Data Links Plot descr. Flight descr.

Copyright KNMI --- Last modified: Thursday, 16-Nov-2006 09:27:38 UTC
Please mail any comments or questions to: velthoveATknmi.nl