Dynamics of the mesosphere and lower thermosphere as seen by MF radars and by the high‐resolution Doppler imager/UARS

Khattatov, B.; Geller, Marvin A.; Yudin, V. A.; Hays, P. B.; Skinner, W. R.; Burrage, M. D.; Franke, Steven; Fritts, David C.; Isler, Joseph R.; Manson, A. H.; Meek, C. E.; McMurray, Robert E.; Singer, W.; Hoffmann, P.; Vincent, R. A.

doi:10.1029/95jd01704

Cited by 55 publications

(57 citation statements)

References 21 publications

(11 reference statements)

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“…Burrage et al, 1996;Khattatov et al, 1996). It is not obvious that these di erences re¯ect a poor wind measurement per se, but if the radar is not measuring the wind accurately, it will obviously lead to errors in the calculations we present.…”

Section: Numerical Techniques and Datamentioning

confidence: 94%

A new technique for evaluating mesospheric momentum balance utilizing radars and satellite data

et al. 2000

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Abstract.A new method for evaluating momentum balance in the mesosphere using radar and satellite data is presented. This method is applied to radar wind data from two medium frequency installations (near Adelaide, Australia and Christchurch, New Zealand) and satellite temperature data from the Improved Stratospheric and Mesospheric Sounder (ISAMS). Because of limitations in data availability and vertical extent, the technique can only be applied to evaluate the momentum balance at 80 km above the radar sites for May 1992. The technique allows the calculation of the residual terms in the momentum balance which are usually attributed to the e ects of breaking gravity waves. Although the results are inconclusive above Adelaide, this method produces values of zonal and meridional residual accelerations above Christchurch which are consistent with expectation. In both locations it is apparent that geostrophic balance is a poor approximation of reality. (This result is not dependent on a mismatch between the radar and satellite derived winds, but rather is inherent in the satellite data alone.) Despite signi®cant caveats about data quality the technique appears robust and could be of use with data from future instruments.

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Section: Numerical Techniques and Datamentioning

confidence: 94%

A new technique for evaluating mesospheric momentum balance utilizing radars and satellite data

et al. 2000

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“…In validation studies, the variability of the observed values has often been expressed by the mean-square di erence of the anomalies (e.g., Khattatov et al, 1996):…”

Section: Estimation Of the Precisionmentioning

confidence: 99%

Validation of HRDI MLT winds with meteor radars

et al. 1997

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Abstract. A validation study of the mesospheric and lower-thermospheric (MLT) wind velocities measured by the High-Resolution Doppler Imager (HRDI) on board the Upper-Atmosphere Research Satellite (UARS) has been carried out, comparing with observations by meteor radars located at Shigaraki, Japan and Jakarta, Indonesia. The accuracy of the HRDI winds relative to the meteor radars is obtained by a series of simultaneous wind measurements at the time of UARS overpasses. Statistical tests on the di erence in the wind vectors observed by HRDI and the meteor radars are applied to determine whether the wind speed has been overestimated by HRDI (or underestimated by the MF radars) as previously noticed in HRDI vs. MF radar comparisons. The techniques employed are the conventional t-test applied to the mean values of the paired wind vector components as well as wind speeds, and two nonparametric tests suitable for testing the paired wind speed. The square-root transformation has been applied before the t-tests of the wind speed in order to ®t the wind-speed distribution function to the normal distribution. The overall results show little evidence of overestimation by HRDI (underestimation by meteor radars) of wind velocities in the MLT region. Some exceptions are noticed, however, at the altitudes around 88 km, where statistical di erences occasionally reach a level of signi®cance of 0.01. The validation is extended to estimate the precision of the wind velocities by both HRDI and meteor radars. In the procedure, the structure function de®ned by the mean square di erence of the observed anomalies is applied in the vertical direction for the pro®le data. This method assumes the isotropy and the homogeneity of variance for the physical quantity and the homogeneity of variance for the observational errors. The estimated precision is about 6 m s À1 for the Shigaraki meteor radar, 15 m s À1 for the Jakarta meteor radar, and 20 m s À1 for HRDI at 90-km altitude. These values can be used to con®rm the statistical signi®cance of the wind ®eld obtained by averaging the observed winds.

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“…In this comparison it will be obvious that there are some signi®cant di erences between the ground-based and satellite-based estimates of mean, tidal, and planetary wave parameters. Although not fully resolved, this issue has been addressed at a number of workshops (Geller, 1994), and in recent papers by Khattatov et al, (1996) and Burrage et al (1996). Therefore, in cases where the ground-and satellite-based measurements disagree we will provide our best estimate of the model performance based upon current knowledge of possible instrumental biases and refer the reader to the aforementioned references for additional information.…”

Section: Introductionmentioning

confidence: 99%

An intercomparison between the GSWM, UARS, and ground based radar observations: a case-study in January 1993

et al. 1997

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Abstract. The Global-Scale Wave Model (GSWM) is a steady-state two-dimensional linearized model capable of simulating the solar tides and planetary waves. In an e ort to understand the capabilities and limitations of the GSWM throughout the upper mesosphere and thermosphere a comparative analysis with observational data is presented. A majority of the observational data used in this study was collected during the World Day campaign which ran from 20 January to 30 January 1993. During this campaign data from 18 ground-based observational sites across the globe and two instruments located on the UARS spacecraft were analyzed. Comparisons of these data with the simulations from the GSWM indicate that the GSWM results are in reasonable agreement with the observations. However, there are a number of cases where the agreement is not particularly good. One such instance is for the semidiurnal tide in the northern hemisphere, where the GSWM estimates may exceed observations by 50% . Through a number of numerical simulations, it appears that this discrepancy may be due to the eddy di usivity pro®les used by the GSWM. Other di erences relating to the diurnal tide and the quasi-two-day wave are presented and discussed. Additionally, a discussion on the biases and aliasing di culties which may arise in the observational data is also presented.

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Dynamics of the mesosphere and lower thermosphere as seen by MF radars and by the high‐resolution Doppler imager/UARS

Cited by 55 publications

References 21 publications

A new technique for evaluating mesospheric momentum balance utilizing radars and satellite data

A new technique for evaluating mesospheric momentum balance utilizing radars and satellite data

Validation of HRDI MLT winds with meteor radars

An intercomparison between the GSWM, UARS, and ground based radar observations: a case-study in January 1993

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