Hindcasting

Past lake-water chemistry changes can be determined by comparison of historical with current measurements hindcasts using empirical and dynamic computer models space-for-time substitutions (i.e., comparisons between the affected lakes and similar but unaffected lakes) and paleolimnological studies. Of these, paleolimnology is the only approach that does not require the existence of historical data or a thorough understanding of all important watershed and in-lake biogeochemical processes. 

The climatological characteristics of sea states at individual positions and in all parts of the Baltic Sea are presented. Shipboard observations, measurements at fixed positions on the coast and in the open sea as well as calculations using numerical models (hindcasts) were used to calculate the characteristics. 

Open Sea Wave Climate One of the first climatologies used to describe the statistical characteristics of the sea state for different subareas of the Baltic Sea was published by the Registrar of the USSR (1974). This climatology is based on wind (hindcast) and sea state observations. It provides a climatology for four subareas of the Baltic Sea ... 

The former Hydrometeorological Service of the USSR prepared and published a sea state climatology of the Baltic Sea (Gidrometeorologiceskie Uslovija selfovoj zony morjej SSSR, 1983), which is also based on wave and wind observations (hindcast). This paper includes Fig. 7.15 that shows the highest waves with a return interval of 50 years. 

Weisse (2007) has recently completed a hindcast study about the sea state conditions in the Baltic Sea for a 10 year period (1992-2002). On the basis of this model, data set Weisse (2007) has calculated the following wave characteristics for 19 positions ... 

Figure 7.16 displays the positions for which climatological characteristics were calculated from both observations (DWD, ) and hindcast (Weisse, 2007). The 11 position pairs selected are in close distance with each or coincide. 

From Fig. 7.17 and particularly from Fig. 7.18, it is evident that the differences between observational and hindcast data are substantial on some positions, particularly in the winter. However, the comparison of statistic parameters, which were computed on the one hand from observation data and on the other hand using data from wave models (hindcast), is not unproblematic for the following reasons ... 

Augustin (2005) found the absolute maximum value of the significant wave heights (10 m) in the eastern part of the Southern Baltic Sea, which corresponds to the latest hindcast studies of Weisse (2007), see Table 7.9. This is also the order of magnitude of the extremes that were determined by various weather services for the hurricanes Anatol (1999) and Erwin/Gudrun (2005—see Section 1.1.6). 

Table 7.11 contains a comparison of significant wave heights for the northern Baltic Sea. The data of Weisse (2007) and Augustin (2005) are based on model hindcast simulations for different time periods. 

TABLE 7.8 Monthly Means of Significant Wave Heights Derived from Ship Ohservations (DWD,) and Hindcast (Weisse, 2007)... 

The averages of the monthly maxima of a 50-year observation period and a 10 year hindcast period (Weisse, 2007) were calculated and compiled inTable 7.13 (see also data CD). 

Weisse, R., 2007. A Sea State Hindcast for the Baltic Sea 1992-2002, unpublished manuscript. Wenzel, H.-G., 1976. Zur Genauigkeit von gravimetrischen Erdgezeitenbeobachtungen, Wissenschaf-... 

However, such an approach decreases the predictive capability and Emits the value for hindcasting of the regional climate of the last centuries. For this purpose atmosphere, ice, and ocean state variables must be simulated jointly, because they require each other mutually for the calculation of surface fluxes. This can be accomplished by coupled atmosphere-ice-ocean simulations, supplemented by a land model to compute the runoff of rivers from the Baltic catchment area. Such coupled model configurations are under development and have been applied for case studies (see Lehmann et al., 2004 Kjellstrom et al., 2005). 

Meier, H. E. M., Doscher, R., Coward, A. C., Nycander, J., Dobs, K., 1999. RCO-Rossby Centre regional climate model model description (version 1.0) and first results from the hindcast period 1992/93. Swedish Meteorological and Hydrological, Institute, Norrkbping, Sweden, Report 26, 102 pp. 

Typical drivability analyses, (a) Calculated blow count versus soil resistance for an overconsolidated soil profile as a function of a pipe pile diameter, wall thickness, hammer size, and penetration, (b) Empirical (e) figure correlating hindcasted inner to outer skin friction to depth. (Continued)... 

Circulation hindcasts Retrospective description of circulation processes, through numerical modeling. 

Table II identifies some of the main CORIE circulation codes, and highlights their differences. Because the modeling products include daily (and in the future, real-time) forecasts, and multiyear hindcasts, computational performance is very important simulations that run about 10 times faster than clock time are a desirable target. Table III illustrates the computational efii-ciency of the codes that are currently used for generation of 2D and 3D circulation forecasts, respectively, and shows a clear improvement of computational performance the most recent 3D code runs substantially faster than an older 2D code, using the same computer hardware.

No model of the Columbia River circulation will be realistic, in a multipiupose sense, without accoimting for most of these various forcings. The CORE infrastructure is designed to provide forcing conditions to both hindcast and forecast simulations. The latter simulations are most... 

Developed by Ip (1995), QUODDY was used in early CORIE hindcasts of 3D baroclinic circulatiotL... 

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