A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data
This paper describes the comprehensive homogenization of the "Global Radiosonde and tracked balloon Archive on Sixteen Pressure levels" (GRASP) wind records. Many of those records suffer from artificial shifts that need to be detected and adjusted before they are suitable for climate studi...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-09-01
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| Series: | Earth System Science Data |
| Online Access: | http://www.earth-syst-sci-data.net/6/297/2014/essd-6-297-2014.pdf |
| _version_ | 1819171499652677632 |
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| author | L. Ramella Pralungo L. Haimberger |
| author_facet | L. Ramella Pralungo L. Haimberger |
| author_sort | L. Ramella Pralungo |
| collection | DOAJ |
| description | This paper describes the comprehensive homogenization of the "Global
Radiosonde and tracked balloon Archive on Sixteen Pressure levels" (GRASP)
wind records. Many of those records suffer from artificial shifts that need
to be detected and adjusted before they are suitable for climate studies.
<br><br>
Time series of departures between observations and the National Atmospheric
and Oceanic Administration 20th-century (NOAA-20CR) surface pressure only
reanalysis have been calculated offline by first interpolating the
observations to pressure levels and standard synoptic times, if needed, and
then interpolating the gridded NOAA-20CR standard pressure level data
horizontally to the observation locations. These difference time series are
quite sensitive to breaks in the observation time series and can be used for
both automatic detection and adjustment of the breaks.
<br><br>
Both wind speed and direction show a comparable number of breaks, roughly one
break in three stations. More than a hundred artificial shifts in wind
direction could be detected at several US stations in the period 1938/1955.
From the 1960s onward the wind direction breaks are less frequent. Wind speed
data are not affected as much by measurement biases, but one has to be aware
of a large fair-weather sampling bias in early years, when high wind speeds
were much less likely to be observed than after 1960, when radar tracking was
already common practice. This bias has to be taken into account when calculating
trends or monthly means from wind speed data.
<br><br>
Trends of both wind speed and direction look spatially more homogeneous after
adjustment. With the exception of a widespread wind direction bias found in
the early US network, no signs of pervasive measurement biases could be found.
The adjustments can likely improve observation usage when applied during data
assimilation. Alternatively they can serve as a basis for validating
variational wind bias adjustment schemes. Certainly, they are expected to
improve estimates of global wind trends.
<br><br>
All the homogeneity adjustments are available in the PANGAEA archive
with associated <a href="http://dx.doi.org/10.1594/PANGAEA.823617"target="_blank">doi:10.1594/PANGAEA.823617</a>. |
| first_indexed | 2024-12-22T19:52:16Z |
| format | Article |
| id | doaj.art-8b9069424fb842e0b832cbdc745af4a7 |
| institution | Directory Open Access Journal |
| issn | 1866-3508 1866-3516 |
| language | English |
| last_indexed | 2024-12-22T19:52:16Z |
| publishDate | 2014-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth System Science Data |
| spelling | doaj.art-8b9069424fb842e0b832cbdc745af4a72022-12-21T18:14:31ZengCopernicus PublicationsEarth System Science Data1866-35081866-35162014-09-016229731610.5194/essd-6-297-2014A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind dataL. Ramella Pralungo0L. Haimberger1Department of Meteorology and Geophysics, University of Vienna, Althanstrasse 14, 1090 Vienna, AustriaDepartment of Meteorology and Geophysics, University of Vienna, Althanstrasse 14, 1090 Vienna, AustriaThis paper describes the comprehensive homogenization of the "Global Radiosonde and tracked balloon Archive on Sixteen Pressure levels" (GRASP) wind records. Many of those records suffer from artificial shifts that need to be detected and adjusted before they are suitable for climate studies. <br><br> Time series of departures between observations and the National Atmospheric and Oceanic Administration 20th-century (NOAA-20CR) surface pressure only reanalysis have been calculated offline by first interpolating the observations to pressure levels and standard synoptic times, if needed, and then interpolating the gridded NOAA-20CR standard pressure level data horizontally to the observation locations. These difference time series are quite sensitive to breaks in the observation time series and can be used for both automatic detection and adjustment of the breaks. <br><br> Both wind speed and direction show a comparable number of breaks, roughly one break in three stations. More than a hundred artificial shifts in wind direction could be detected at several US stations in the period 1938/1955. From the 1960s onward the wind direction breaks are less frequent. Wind speed data are not affected as much by measurement biases, but one has to be aware of a large fair-weather sampling bias in early years, when high wind speeds were much less likely to be observed than after 1960, when radar tracking was already common practice. This bias has to be taken into account when calculating trends or monthly means from wind speed data. <br><br> Trends of both wind speed and direction look spatially more homogeneous after adjustment. With the exception of a widespread wind direction bias found in the early US network, no signs of pervasive measurement biases could be found. The adjustments can likely improve observation usage when applied during data assimilation. Alternatively they can serve as a basis for validating variational wind bias adjustment schemes. Certainly, they are expected to improve estimates of global wind trends. <br><br> All the homogeneity adjustments are available in the PANGAEA archive with associated <a href="http://dx.doi.org/10.1594/PANGAEA.823617"target="_blank">doi:10.1594/PANGAEA.823617</a>.http://www.earth-syst-sci-data.net/6/297/2014/essd-6-297-2014.pdf |
| spellingShingle | L. Ramella Pralungo L. Haimberger A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data Earth System Science Data |
| title | A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data |
| title_full | A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data |
| title_fullStr | A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data |
| title_full_unstemmed | A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data |
| title_short | A "Global Radiosonde and tracked-balloon Archive on Sixteen Pressure levels" (GRASP) going back to 1905 – Part 2: homogeneity adjustments for pilot balloon and radiosonde wind data |
| title_sort | global radiosonde and tracked balloon archive on sixteen pressure levels grasp going back to 1905 ndash part 2 homogeneity adjustments for pilot balloon and radiosonde wind data |
| url | http://www.earth-syst-sci-data.net/6/297/2014/essd-6-297-2014.pdf |
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