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Deriving dynamics from GPS radio occultation: Three-dimensional wind fields for monitoring the climate.

Scherllin-Pirscher B, Steiner AK, Kirchengast G - Geophys Res Lett (2014)

Bottom Line: Global Positioning System (GPS) radio occultation (RO) measurements are proven highly useful for observing the thermal structure of the troposphere and stratosphere.Here we use RO data for the first time to derive climatological wind fields from sampling error-corrected geopotential height fields on isobaric surfaces from about 800 hPa to 3 hPa.These results demonstrate that RO wind fields are of high quality and can provide new information on troposphere-stratosphere dynamics, for the benefit of monitoring the climate from weekly to decadal scales.

View Article: PubMed Central - PubMed

Affiliation: Wegener Center for Climate and Global Change (WEGC) and Institute for Geophysics, Astrophysics, and Meteorology/Institute of Physics (IGAM/IP), University of Graz Graz, Austria.

ABSTRACT

Global Positioning System (GPS) radio occultation (RO) measurements are proven highly useful for observing the thermal structure of the troposphere and stratosphere. Here we use RO data for the first time to derive climatological wind fields from sampling error-corrected geopotential height fields on isobaric surfaces from about 800 hPa to 3 hPa. We find monthly mean RO geostrophic wind and gradient wind fields (2007 to 2012, about 500 km horizontal resolution, outside tropics) to clearly capture all main wind features, with differences to atmospheric analysis winds being, in general, smaller than 2 m/s. Larger differences (up to 10 m/s) occur close to the subtropical jet where RO winds underestimate actual winds. Such biases are caused by the geostrophic and gradient wind approximations, while RO retrieval errors introduce negligible effect. These results demonstrate that RO wind fields are of high quality and can provide new information on troposphere-stratosphere dynamics, for the benefit of monitoring the climate from weekly to decadal scales.

No MeSH data available.


Related in: MedlinePlus

Geographic maps (outside the tropics) of (top row) RO geostrophic wind speed, (middle row) its difference to ECMWF wind speed, and (bottom row) difference between RO gradient wind speed and ECMWF wind speed, at 200 hPa in January 2009 (left column) and July 2009 (right column).
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fig02: Geographic maps (outside the tropics) of (top row) RO geostrophic wind speed, (middle row) its difference to ECMWF wind speed, and (bottom row) difference between RO gradient wind speed and ECMWF wind speed, at 200 hPa in January 2009 (left column) and July 2009 (right column).

Mentions: Geostrophic wind speeds at 200 hPa (Figure 2, top row) are largest in the winter hemisphere at mid-latitudes, representing the subtropical jet. In NH winter (January 2009) maximum monthly mean wind speed (>60 m/s) is found at 30°N above East Asia and the western Pacific. In SH winter (July 2009), maximum wind speed is slightly smaller (<60 m/s) but more symmetric than in the NH.


Deriving dynamics from GPS radio occultation: Three-dimensional wind fields for monitoring the climate.

Scherllin-Pirscher B, Steiner AK, Kirchengast G - Geophys Res Lett (2014)

Geographic maps (outside the tropics) of (top row) RO geostrophic wind speed, (middle row) its difference to ECMWF wind speed, and (bottom row) difference between RO gradient wind speed and ECMWF wind speed, at 200 hPa in January 2009 (left column) and July 2009 (right column).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4459209&req=5

fig02: Geographic maps (outside the tropics) of (top row) RO geostrophic wind speed, (middle row) its difference to ECMWF wind speed, and (bottom row) difference between RO gradient wind speed and ECMWF wind speed, at 200 hPa in January 2009 (left column) and July 2009 (right column).
Mentions: Geostrophic wind speeds at 200 hPa (Figure 2, top row) are largest in the winter hemisphere at mid-latitudes, representing the subtropical jet. In NH winter (January 2009) maximum monthly mean wind speed (>60 m/s) is found at 30°N above East Asia and the western Pacific. In SH winter (July 2009), maximum wind speed is slightly smaller (<60 m/s) but more symmetric than in the NH.

Bottom Line: Global Positioning System (GPS) radio occultation (RO) measurements are proven highly useful for observing the thermal structure of the troposphere and stratosphere.Here we use RO data for the first time to derive climatological wind fields from sampling error-corrected geopotential height fields on isobaric surfaces from about 800 hPa to 3 hPa.These results demonstrate that RO wind fields are of high quality and can provide new information on troposphere-stratosphere dynamics, for the benefit of monitoring the climate from weekly to decadal scales.

View Article: PubMed Central - PubMed

Affiliation: Wegener Center for Climate and Global Change (WEGC) and Institute for Geophysics, Astrophysics, and Meteorology/Institute of Physics (IGAM/IP), University of Graz Graz, Austria.

ABSTRACT

Global Positioning System (GPS) radio occultation (RO) measurements are proven highly useful for observing the thermal structure of the troposphere and stratosphere. Here we use RO data for the first time to derive climatological wind fields from sampling error-corrected geopotential height fields on isobaric surfaces from about 800 hPa to 3 hPa. We find monthly mean RO geostrophic wind and gradient wind fields (2007 to 2012, about 500 km horizontal resolution, outside tropics) to clearly capture all main wind features, with differences to atmospheric analysis winds being, in general, smaller than 2 m/s. Larger differences (up to 10 m/s) occur close to the subtropical jet where RO winds underestimate actual winds. Such biases are caused by the geostrophic and gradient wind approximations, while RO retrieval errors introduce negligible effect. These results demonstrate that RO wind fields are of high quality and can provide new information on troposphere-stratosphere dynamics, for the benefit of monitoring the climate from weekly to decadal scales.

No MeSH data available.


Related in: MedlinePlus