A comparison of various normal-mode initialization schemes and the
                        inclusion of diabatic processes

Errico, Ronald M.; Rasch, Philip J.

doi:10.3402/tellusa.v40i1.11779

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…Sardeshmukh and Liebmann (1993) have further demonstrated the inconsistencies between the ECMWF and NCEP divergence fields for 1988-89. Diabatic initialization of the analyzed fields imposes a somewhat artificial balance that may overstrengthen zonal mean meridional circulations (Errico and Rasch 1988), although it tends to reduce the divergence locally.…”

Section: B Atmospheric Divergencementioning

confidence: 99%

Using Atmospheric Budgets as a Constraint on Surface Fluxes

Trenberth¹

1997

J. Climate

112

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Possible methods for estimating surface fluxes include (i) use of bulk fluxes and in situ observations, (ii) use of model parameterizations to interpret specified inputs and compute surface fluxes, and (iii) various indirect methods, which rely on the fact that the mass and surface heat, energy, and momentum budgets must balance and so, given computations of all the other components in the various budget equations applied to fields either within the ocean or the atmosphere, fluxes may be inferred as a residual. This paper reviews the third approach using indirect methods and outlines the advantages associated with the use of global atmospheric analyses from four-dimensional data assimilation (4DDA). The time mean increment required in producing analyses in 4DDA is identical to the systematic short-term (6 h) assimilating model forecast error and is most likely due to errors in the model physics. Therefore, the analyses include a desirable fix, which allows the sum of the ''physics'' to be deduced from ''dynamics.'' The focus is on the heat and moisture budgets to infer surface heat fluxes and freshwater fluxes, but with the recognition of the need to balance the mass budget as well. The diurnal cycle of the vertically integrated mass budget for July 1985 and January 1996 from National Centers for Environmental Prediction (formerly the National Meteorological Center) reanalyses is presented, revealing the strong semidiurnal tide and highlighting the need for at least four-times-daily data. The new results reveal that gross violations of the mass budget continue to be present, but these can be allowed for. A discussion is given of other sources of errors contributing to the heat and moisture budgets.

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Section: B Atmospheric Divergencementioning

confidence: 99%

Using Atmospheric Budgets as a Constraint on Surface Fluxes

Trenberth¹

1997

J. Climate

112

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“…The present study deals strictly with diabatic heating from cumulus convection. A convective heating term is incorporated in the balance condition for the high-frequency normal modes (Bengtsson 1981;Errico and Rasch 1988;Kitade 1983;Wergen 1983). With the inclusion of heating corresponding to observed rainfall data in the diabatic forcing term, the initialization can force the model state toward the real atmospheric state.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Forecasting

Hyman¹,

Shi²,

Czarnaski³

et al. 2000

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Numerical experiments were conducted to assess the impact of Omegadropwindsonde (ODW) data and Special Sensor Microwave/Imager (SSM/I) rain rates in the analysis and prediction of Hurricane Florence (1988). The ODW data were used to enhance the initial analysis that was based on the National Meteorological Center/Regional Analysis and Forecast System (NCEP/RAFS) 2.5° analysis at 0000 UTC 9 September 1988. The SSM/I rain rates at 0000 and 1200 UTC 9 September 1988 were assimilated into the Naval Research Laboratory's limited-area model during model integration.Four numerical simulations were performed to assess the impact of ODW data and SSM/I rain rates on numerical forecasts of Hurricane Florence (1988). A nested three-pass Barnes scheme objective analysis was used to enhance the NCEP/RAFS 2.5° analysis because of the relative high resolution of the ODW data near the center of Florence. The NCEP/RAFS 2.5° analysis and the ODW enhanced analysis were then used as the initial conditions for the numerical prediction experiments. We found that the forecast error of the intensity was reduced from 14 to 4 mb with the assimilation of the ODW data. It is also clear that the ODW data reduced the forecast error of the landfall time in the control experiment by 5 hours (down from 9 to 4 hours), and the landfall location error by 95% (down from 294 to 15 km). The impact of the ODW data was more pronounced in the first 24 hours of the integration and gradually decreased beyond 24 hours. This result is in agreement with Franklin and DeMaria (1992), in which a barotropic, nested, spectral hurricane track forecasting model was used to determine the impact of the ODW data. The advantage of using a three-dimensional primitive equation model with the inclusion of baroclinic and physical processes, as in this study, is that the model can simulate the hurricane structure in more detail (DeMaria et al., 1992).However, a major limitation of the ODW observations is that they do not provide information above 400 mb because of the altitude limitations of the NOAA WP-3D, while satellite-derived winds can provide some upper-level information . Detailed observations of the three-dimensional structure of the upper levels of tropical cyclones are extremely scarce. Dropsonde data collected from 200 mb to the surface by the recent TCM-90 experiment (Elsberry and Abbey, 1991) may be proven to be very useful in depicting the upper-level structure of tropical cyclones (Merrill and Velden, 1995).The rainfall rates retrieved from the SSM/I data at 0000 UTC and 1200 UTC 9September 1988 were assimilated into the NRL limited-area model initialized with the NCEP/RAFS 2.5° analysis (Exp. Control+SSMI) and the ODW enhanced analysis (Exp. ODW+SSMI). Results indicate that the assimilation of the SSM/I rain rates (Exp.Control+SSMI) reduced the 24-hour forecast errors in the landfall location in the control experiment by about 43% (down from 294 to 169 km), and the landfall time by 5 hours (down from 9 to 4 hours). At mean time, the 24-hour minimum SLP and ...

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