Observation of horizontal winds in the middle-atmosphere between 30° S and 55° N during the northern winter 2009–2010

Abstract

Although the links between stratospheric dynamics, climate and weather have been demonstrated, direct observations of stratospheric winds are lacking. We report observations of winds between 8 and 0.01 hPa (~35–80 km) from October 2009 to April 2010 by the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station. The altitude range covers the region between 35–60 km where previous space-borne wind instruments show a lack of sensitivity. Both zonal and meridional wind components were obtained, though not simultaneously, in the latitude range from 30&deg; S to 55&deg; N and with a single profile precision of 7–9 m s^&minus;1 between 8 and 0.6 hPa and better than 20 m s^&minus;1 at altitudes above. The vertical resolution is 5–7 km except in the upper part of the retrieval range (10 km at 0.01 hPa). In the region between 1–0.05 hPa, a mean difference <2 m s^&minus;1 is found between SMILES profiles retrieved from different spectroscopic lines and instrumental settings. Good agreement (mean difference of ~2 m s^&minus;1) is also found with the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis in most of the stratosphere except for the zonal winds over the equator (mean difference of 5–10 m s^&minus;1). In the mesosphere, SMILES and ECMWF zonal winds exhibit large differences (> 20 m s^&minus;1), especially in the tropics. We illustrate our results by showing daily and monthly zonal wind variations, namely the semi-annual oscillation in the tropics and reversals of the flow direction between 50&deg; N–55&deg; N during sudden stratospheric warmings in the stratosphere. The daily comparison with ECMWF winds reveals that in the beginning of February, a significantly stronger zonal westward flow is measured in the tropics at 2 hPa compared to the flow computed in the analysis (difference of ~20 m s^&minus;1). The results show that the comparison between SMILES and ECMWF winds is not only relevant for the quality assessment of the new SMILES winds but it also provides insights on the quality of the ECMWF winds themselves. Although the instrument was not specifically designed for measuring winds, the results demonstrate that space-borne sub-mm wave radiometers have the potential to provide good quality data for improving the stratospheric winds in atmospheric models

Comparison of co‐located independent ground‐based middle atmospheric wind and temperature measurements with numerical weather prediction models

“…Comparisons of wind fields in the MA from global meteorological data assimilation systems to satellite observations are somewhat limited. Recent studies include comparisons between output from the European Centre for Medium-Range Weather Forecast (ECMWF) analysis with observations from long-duration balloons [Podglajen et al, 2014] and from the Superconducting Submillimeter-Wave Limb-Emission Sounder research instrument on board the international space station [Baron et al, 2013]. Earlier validations also include rocketsonde measurements [e.g., Hamilton, 1991], mesosphere-stratospheretroposphere radar techniques [e.g., Smith and Fritts, 1984], and comparisons with the High Resolution Doppler Interferometer instrument [Hays et al, 1993;Swinbank and Ortland, 2003].…”

Measurement of stratospheric and mesospheric winds with a submillimeter wave limb sounder: results from JEM/SMILES and simulation study for SMILES-2

“…We underline the most important instrumental limitations in order to provide useful information for the preparation of SMILES-2. We use the data presented in 10 . The instrument scanned the atmospheric limb from the Earth's surface to the mesosphere.…”

“…SMILES single profiles and collocated ECMWF ones are paired and average in the same way. 10 In mid-latitudes and at 1 hPa, the differences between the two line-of-sight winds are on average 2 m s −1 (horizontal dashed-lines). This good agreement suggests the good quality of both SMILES measurement and ECMWF forecast in this region.…”

“…[6][7][8] Horizontal winds have been derived from the Millimeter Limb Sounder (MLS) and the Submillimeter Wave Limb Emission Sounder (SMILES). 9,10 From SMILES measurements, lineof-sight winds were retrieved from 30 km (theoretical limits of 25 km) to ≈80 km (≈100 km in night time). A ground-based millimeter radiometer has also recently been developed for wind observations in the same altitude range.…”

Feasibility Study for Future Spaceborne Coherent Doppler Wind Lidar, Part 2: Measurement Simulation Algorithms and Retrieval Error Characterization

“…The only spaceborne wind profile measurements currently available have been performed using passive remote sensing techniques, and their altitude range is limited to the middle and upper atmosphere above 30 km (Baron et al 2013). In order to address the strong demand for global observations in the troposphere (Baker et al 2014), the European Space Agency (ESA) plans to launch the Atmospheric Dynamics Mission Aeolus equipped with a direct-detection lidar at l = 355 nm (Stoffelen et al 2005).…”