On the Impact of Sapce-based Observing Systems in the JMA Global Forecast/Analysis System

Kashiwagi, Kenji

doi:10.2151/jmsj1965.65.2_189

Cited by 8 publications

(2 citation statements)

References 21 publications

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“…Since the latter half of the 1970s there has been more active development of data assimilation methods; optimum interpolation methods were developed (Schlatter et al, 1976;Bergman,1979;Lorenc,1981;Kashiwagi, 1987) and have been operational in most of the N WP centers in the world. However, we could not find significant improvements in the field of data quality control until the almost end of 1980s.…”

Section: Introductionmentioning

confidence: 99%

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A Data Quality Control Method Using Forecasted Horizontal Gradient and Tendency in a NWP System

Onogi

1998

Journal of the Meteorological Society of Japan

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A method of quality control (QC) to reject erroneous observational data has been developed in the Numerical Weather Prediction System of the Japan Meteorological Agency (JMA). Each observed value is processed in the QC, by evaluating its deviation from the first guess (FG) value given by the forecasted field, comparing it with a threshold value defined by statistics and rejecting it if it falls outside the threshold range. In the previous method (Static QC), the threshold value was defined as a constant regardless of the weather conditions.In the new method (Dynamic QC, in this paper), the threshold value is defined as a variable linearly depending on the local horizontal gradient and three-hour tendency of the FG. With a statistical study, we found a relationship between the deviations, and both the horizontal gradient and the tendency of FG were approximately proportional. Then this relationship was applied to the Dynamic QC. In almost all regions, the Dynamic QC reduces erroneous judgements given in the Static QC where wrong observed values were accepted in less disturbed weather conditions and right values were rejected in more disturbed conditions. Forecast experiments using the Dynamic QC revealed that the forecast scores and the fit in root mean square error (RMSE) to rawinsonde observations were improved in the tropics and the Southern Hemisphere in winter. For some cases, the improvement of the scores in Anomaly Correlation Coefficient (ACC) was equivalent to more than one days extension of the forecast term, and the ratios of fit in RMSE were improved by more than 10 %. The forecast results for the Northern Hemisphere were neutral. The Dynamic QC method was put into operations at JMA on March 17, 1997. After that, the scores of the operational global forecasts have significantly improved.

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Section: Introductionmentioning

confidence: 99%

“…If the absolute value of the residual between the observed value and forecast value was larger than a certain limiting value, the datum was judged to be wrong and removed (Kashiwagi, 1987;Kashiwagi and Baba, 1989). We will refer to this type of QC as "Static QC."…”

Section: Introductionmentioning

confidence: 99%

A Data Quality Control Method Using Forecasted Horizontal Gradient and Tendency in a NWP System

Onogi

1998

Journal of the Meteorological Society of Japan

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Inversion of cloudy satellite sounding radiances by nonlinear optimal estimation. I: Theory and simulation for TOVS

Eyre

1989

Quart J Royal Meteoro Soc

141

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A new approach is proposed for inverting satellite sounding data for use in numerical weather prediction (NWP). It may be considered in two ways: either as a retrieval scheme which uses a forecast profile as a background or 'first guess' and the covariance of forecast error as a constraint in order to produce retrieved profiles compatible with the subsequent NWP analysis; or as a module within a NWP analysis scheme to perform the vertical analysis of satellite radiances at the observation points (i.e. to project the information in the radiances on to the NWP analysis levels in the vertical). The new scheme performs an inversion of the radiances to retrieve simultaneously the temperature and humidity profiles, the surface temperature and microwave emissivity, and the cloud-top pressure and amount. It employs an iterative method which finds the maximum probability solution to a nonlinear retrieval/analysis problem. It operates on 'raw', potentially cloudaffected radiances and thus bypasses the separate pre-processing and cloud-clearing stages necessary in many retrieval schemes. The technique is a fully 'physical' method, involving calculations for each profile of corresponding radiances (and of derivatives of radiance with respect to profile parameters). It is also a 'statistical' method, since it uses the covariance of forecast error as a constraint.The paper develops the theory of the new approach and examines its convergence properties and inherent quality control characteristics. The application of the scheme to data from the TIROS Operational Vertical Sounder (TOVS) is then discussed. The theoretical error characteristics of the scheme are investigated, and the results of retrievals from simulated TOVS radiances are presented. The theoretical advantages of retrieving cloud parameters simultaneously with other variables are demonstrated, in terms of both the temperature retrieval accuracies in cloudy conditions and the skill with which the cloud parameters themselves may be obtained.

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Atmospheric soundings from satellites—false expectation or the key to improved weather prediction?

Smith

1991

Quart J Royal Meteoro Soc

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Temperature and water vapour soundings from satellites have been available for more than 20 years. Because of the global nature of these data, satellite soundings were expected to improve significantly global numerical weather prediction (NWP). Indeed, experiments with the satellite soundings provided during the Global Weather Experiment (GWE) in 1979 revealed the positive impact of these data on extended‐range forecasts, particularly in the southern hemisphere. Unfortunately, since the GWE, the value of satellite soundings has apparently diminished. I believe this to be due largely to improvements in the models which have surpassed the inherently poor vertical resolution of these data relative to that of the contemporary NWP models. The satellite data can even degrade the analysis/forecast operation through the aliasing of small‐scale features which may be properly represented by the vertical scale resolved by the model. This lecture addresses, from a historical perspective, the dilemma of the decreasing value of satellite soundings in the weather‐forecast application (i.e., the reasons for the unfulfilled expectations of these data). Attention is then turned to the improvements in the satellite technology and the application techniques needed to reverse this trend.

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On the Impact of Sapce-based Observing Systems in the JMA Global Forecast/Analysis System

Cited by 8 publications

References 21 publications

A Data Quality Control Method Using Forecasted Horizontal Gradient and Tendency in a NWP System

A Data Quality Control Method Using Forecasted Horizontal Gradient and Tendency in a NWP System

Inversion of cloudy satellite sounding radiances by nonlinear optimal estimation. I: Theory and simulation for TOVS

Atmospheric soundings from satellites—false expectation or the key to improved weather prediction?

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