Temperature and Pressure Service


Contents:
  • Abstract.
  • Introduction
  • Temperature and pressure data
  • Service Information
  • Plots
  • Data for downloading
  • Data citation
  • Other Services
  • Abstract

    This page provides links to files relevant to the service of the pressure and temperature provided by NVI Inc. and the VLBI group at NASA Goddard Space Flight Center. The service provides interpolated and extrapolated temperature and pressure time series every 6th hours from 1979 to 2014 for all VLBI sites and are updated every month when new data is released by the ECMWF. The last update was done on August 2nd, 2016. The last date processed is April 30, 2016.

    Introduction

    Both temperature and pressure are used in VLBI processing, pressure for the atmospheric delay and temperature for the thermal deformation of the antenna. The atmospheric delay is divided into two components, the wet zenith delay and the hydrostatic delay. Together these two components describe the delay caused by the refraction through the atmosphere. Surface pressure is proportional to the hydrostatic delay. A bias in the surface pressure will therefore add a bias to the hydrostatic delay and jumps will add jumps to the hydrostatic delay. This will cause errors in the estimates of baseline lengths and the position estimates for the stations. The temperature will cause a deformation of the VLBI antenna. This causes a displacement of the VLBI reference point with respect to the mean position. The distortion is modeled as linear expansion in a symmetric way. Pressure and temperature from models are often homogenous and can therefore improve processing.

    Temperature and pressure data

    European Centre for Medium-Range Weather Forecasts (ECMWF) [www.ecmwf.int] provides 2 meter layer temperature and surface pressure on a 1.5x1.5 degree equal angular grid for the entire Earth. This temperature and pressure data has been extrapolated to the station height and interpolated to the position of the station.

    Service Information

    The temperature and pressure series are computed for 171 VLBI sites, from 1979 to 2015.

    Plots

    These plots show the temperature and pressure for the VLBI station Westford from 2002 to 2012. The data called Mark-3 databases is values extracted from the database used at GSFC, ideally measurements from a sensor on site. The data called ECMWF is the interpolated and extrapolated data provided here.

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    Data for downloading

    Temperature and pressure series

    File Format Size Comment
    1979.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1979
    1980.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1980
    1981.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1981
    1982.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1982
    1983.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1983
    1984.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1984
    1985.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1985
    1986.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1986
    1987.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1987
    1988.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1988
    1989.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1989
    1990.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1990
    1991.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1991
    1992.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1992
    1993.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1993
    1994.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1994
    1995.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1995
    1996.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1996
    1997.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1997
    1998.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1998
    1999.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 1999
    2000.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2000
    2001.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2001
    2002.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2002
    2003.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2003
    2004.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2004
    2005.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2005
    2006.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2006
    2007.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2007
    2008.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2008
    2009.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2009
    2010.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2010
    2011.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2011
    2012.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2012
    2013.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2013
    2014.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2014
    2015.zip ASCII 3.0 Mb Temperature and pressure for 171 VLBI stations for 2015
    2016.zip ASCII Temperature and pressure for 171 VLBI stations for 2016

    Data citation

    Temperature and pressure time series provided by the NASA GSFC VLBI group which are available at http://lacerta.gsfc.nasa.gov/met (Juhl, LeBail & Gipson). The time series are computed from the ERA-interim model of the ECMWF (http://apps.ecmwf.int/datasets/data/interim_full_daily/).

    Other Services

    Tropospheric delays:
    http://lacerta.gsfc.nasa.gov/tropodelays
    Hydrology Loading: http://lacerta.gsfc.nasa.gov/hydlo
    Non-tidal ocean loading: http://lacerta.gsfc.nasa.gov/oclo


    This page was created by Johanna Juhl and David Eriksson.


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