PURPOSE AND SCOPE For strong winds (neutral atmosphere)@ estimation methods are provided in ESDU 82026@ 83045@ 85020 and 86010 giving the variation of hourly-mean wind speed@ gusts@ intensities of turbulence and integral length scales and spectral densities of turbulence with height over terrain with roughness changes. For convenience@ tables of wind speed factors and properties of the u-component of turbulence based on these methods are presented in ESDU 84011@ 84030 and 86035 for various combinations of ground roughness at the site and upwind. The computer program used to generate the data for these simple look-up tables has been extensively modified for more general use and expanded to include topographic effects. A number of features have been added to the program to assist practical application. In particular@ the program has now been converted to Visual Basic and is run as a module in Microsoft Excel 97 (or later) using a spreadsheet format for entering data and printing the resultant output. A major modification to the previous version (A9232) is that topographic effects are now computed via a program based on the theoretical model of Deaves rather than on a simplified model which could only be applied conveniently to isolated hills. The program can be used to calculate wind speeds over hilly terrain which may consist of several peaks and troughs. It has also been adapted to provide estimates for steep terrain where flow separation effects occur. Also included is a simplified method for the distortion effect of topography on turbulence. The user is recommended to use Tables 3.1 and 3.2 which provide a summary and guidance for the input data required. The rest of this document supplies more detailed information concerning the input data (cross-referenced in Tables 3.1 and 3.2)@ the use of the program@ an example and the basis of the methods used. The main features of the program are listed in Section 2.1 and the installation and setting up of the program is described in Section 3. A description of the input and output data formats is given in Sections 4 and 5 and a summary of the basis of the methods used is described in Section 6. Examples of the use of the program are given in Section 7 and comparisons with two sets of full-scale measurements on hills are given in Section 9. Other programs which perform some of the same tasks as the program given in this Item have been included previously in ESDU 84011 and 85003. These programs will give values of wind speed and turbulence intensity (Iu) to within a few percent (typically less than 5%) of the values given by the present program for a single roughness change. However@ the present program has a more definitive source (see Section 6) and is likely to be more reliable in general application. It is also more comprehensive and has a research and application role in providing a means of correcting measured data to specified standard conditions. The application of the neutral atmosphere model to tropical storms such as hurricanes and typhoons is discussed in ESDU 87034. It is reasonable to expect that over land the program can be used for such storms at heights below 200 m.