Model Description
RIMPUFF is a fast and operational puff diffusion code that is suitable for real-time simulation of puff and plume dispersion during time and space changing meteorology. Also optimized for fast response on a PC this model is provided with a puff splitting feature to deal with plume bifurcation and flow divergence due to channelling, slope flow and inversion effects in non-uniform terrain.


RIMPUFF includes fast subroutines for the calculation of gamma doses from airborne and deposited radioactive isotopes, released to the atmosphere from a nuclear power plant. These subroutines have been developed in cooperation with CRIP, Budapest.

For real-time applications, RIMPUFF can be driven by wind data from a combination of:

  1. A permanent network of meteorological towers,
  2. The flow models LINCOM and/or MCF (or similar), and
  3. Numerical Weather Forecast data.

The puff or plume diffusion process is in RIMPUFF controlled by the local turbulence levels, either provided directly from on-site measurements, or provided via pre-processor calculations (Mikkelsen and Desiato, 1993). RIMPUFF is further equipped with plume rise formulas, inversion and ground level reflection capabilities, gamma dose algorithms and wet/dry depletion.

LINCOM is a non-hydrostatic diagnostic model based on the solution of linearized continuity and momentum equations with a first order spectral turbulent diffusion closure. It processes a single layer of 100x100 grid points in less than 10 seconds on a 486 PC. Its truncated physics of course restricts its application over severe non-uniform terrain, but considerable realism in the flow fields is achieved by use of assimilation techniques to match results to measured tower or forecast winds. Further, in cooperation with GRS, Köln, RIMPUFF has been interfaced with the mass-consistent flow model MCF. This version of RIMPUFF is connected to RODOS.

A prognostic capability of RIMPUFF is obtained via data link to regional atmospheric forecasting centers operation at several European meteorological institutes. The Danish GRV-HIRLAM forecast model (Machenhauer et al. 1991) covers presently all of the EU countries on a 0.42 deg horizontal resolution polar grid, with a 31 level vertical resolution. Running in a 6 hour updated data-assimilation cycle, this model forecast, e.g., wind, temperature, humidity and pressure up to + 48 hours ahead. A small area version (DK-HIRLAM) covers the Nordic countries and central Europe and runs on a resolution of 0.21 deg (23 km) and forecast at 03 hours intervals up to + 36 Hours. Similar models are now operational at several European meteorological services (Denmark, Holland, Ireland, Sweden, Finland), from where local wind and precipitation forecast are envisioned to be transferred on-line to RODOS users via fast digital telephone network (ISDN), or via computer networks (Internet).


Model evaluation
A series of 15 full-scale dispersion experiments from the 1990 Guardo trials, carried out over complex terrain in Northern Spain are being analyzed. Actual wind and turbulence measurements taken during the experiment are used as input data for a series of simulations made with Risø's combined flow and diffusion model (LINCOM/RIMPUFF). Considerable effort is devoted to the testing of the improved features for taking into account wind shear and plume rise in RIMPUFF. A wind field "fitting" procedure for LINCOM has been tested in simulations of 2 of the Guardo experiments.


The experimental evaluation of flow field and dispersion modeling, using data from the complex terrain SIESTA experiment (SF6 International Experiment in STagnant Air) was continued. Possible improvements of the simulations using multi-level precalculated flow fields are being investigated.

A field study of high-resolution Meteorology And Diffusion Over Non-uniform Areas (MADONA) in the south of England. Several simulations were made on-site and in real-time, while others were made after the experiment during the analyzes of the observed wind and diffusion pattern. Diffusion of smoke and tracer gas during two of the MADONA experiments were simulated using LINCOM/RIMPUFF.

Computer Code
The RIMPUFF computer code was originally developed on the Risø Burroughs B7800 (IBM compatible) computer in the FORTRAN77 language. RIMPUFF has later been converted to VAX FORTRAN77 and this version was used on a VAX 8700 computer. The present version 7 is written in Lahey FORTRAN90 for a PC. A similar version written in HP FORTRAN77 for a HP workstation with UNIX 10.20 operating system is also available.

The minimum requirements for the PC version are:

  • 66 MHZ 486 PC with co-processor
  • 20 Mb RAM
  • 100 Mb Harddisk space available.

Access to RIMPUFF
If you are interested in obtaining RIMPUFF please contact:

Heidi Serny Jacobsen
Sales Assistant
DTU Wind Energy
+45 46 77 59 43 

Thykier-Nielsen S., Deme S. and Láng E. (1993). Calculation method for gamma-dose rates from spherical puffs. Risø-R-692 (EN). Risø National Laboratory, DK-4000 Roskilde, Denmark.

Thykier-Nielsen, S., Mikkelsen T. and Moreno, J. (1993). Experimental evaluation of a pc-based real-time dispersion modeling system for accidental releases in complex terrain. Proceedings from 20th International Technical Meeting on Air Pollution Modelling and its Application , Valencia, Spain, November 29 - December 3., 1993.

Thykier-Nielsen, S., Roed, J. and Nielsen, F. (1994). Consequence Calculations for Large Scale Releases of Radioactivity using RIMPUFF and a Numerical Weather Forecast Model. Presented at COSYMA User Group meeting, KEMA, Arnhem, April 25. to 26., 1994. Risø National Laboratory, DK-4000 Roskilde, Denmark.

Mikkelsen, T. (1992) Atmospheric dispersion models for real-time application in the decision support system being developed within the CEC. In: Olesen, H.R. and T. Mikkelsen (Eds.) 1992: Proceedings of the workshop "Objectives for Next Generation of Practical Short-Range Atmospheric Dispersion Models", Risø, Denmark, May 6-8 Danish Center for Atmospheric Research (DCAR), P.O. BOX 358, DK-4000 Roskilde. pp 109-130.

Mikkelsen, T. and F. Desiato(1993): Atmospheric Dispersion Models and Pre-processing of Meteorological Data for Real-time Application. In: Proceedings of the Third International Workshop on Real-time Computing of the Environmental Consequences of an Accidental Release to the Atmosphere from a Nuclear Installation, Schloss Elmau, Bavaria, October 25-30 1992. Journal of Radiation Protection Dosimetry Vol 50 Nos 2-4, pp 205-218(1993).

Santabàrbara, J.S., T. Mikkelsen, R. Kamada, G. Lai and A.M. Sempreviva (1993): LINCOM Wind Flow Model, Risø-R-report(EN), 37 pp. Available on request from: Department of Meteorology and Wind Energy, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark.

Thykier-Nielsen, S., S. Deme, and E. Láng (1995). Calculation method for gamma-dose rates from Gaussian puffs. Risø-R-775(EN).

Thykier-Nielsen, S., Deme, S. and Mikkelsen T. (1997). RODOS SYSTEM, Analysing Subsystem: RIMPUFF, Stand Alone Version, RIMDOS7, Users Guide, RODOS(A)-TN(95)3.