The TAU MM5 Overview Page

Data Produced by MM5

This is an academic site, which does not replace operational services such as the Israel Meteorological Service. We do not guarantee the timely publication of forecasts, or indeed any publication of forecasts. Nor do we guarantee the accuracy of the published forecasts.

The latest weather forecasts for Israel can also be accessed directly from the ISA-MEIDA main page.
The forecasts are for up to 48 hours after the time the forecast was made.

Please note that times in the forecasts are universal time, also known as Greenwich time . For Israel winter-time two hours have to be added to the hour given in the forecasts, and for Israel summer-time three hours have to be added. For times at other locations see the Date and Time Gateway .

The forecasts are presented as four 33KB GIF figures per page and, if desired, as animations, for each of the parameters sea-level pressure, 850 mbar temperature and wind, and precipitation.
For the precipitation forecasts each figure shows the cumulative precipitation over the 6 hours preceding the "Valid:" time which appears on the figure.

In addition to the above forecasts the latest weather forecast page also has links to time series for temperature, humidity, and precipitation for Tel-Aviv, Jerusalem, Hadera, Beer-Sheva, and Eilon.
Please note that times on the time-series figures are hours after the forecast hour. Therefore if the forecast was made on 12 GMT (12 Z), time 12 is actually 24 GMT.

Additional fields, aimed at the more professional meteorologist, are shown in GIF figures for boundary layer height, Montgomery Potential on 320K level, Montgomery Potential on 330K level, IPV on 320K level, and IPV on 330K level.
IPV stands for Isentropic potential vorticity, and for and introduction to IPV and its uses see the presentations by Dr. Eyal Heifetz in Hebrew, or in English.

Past Forecasts are also available from November 2000 and onwards.

The full data produced by the MM5 model is available through FTP at ftp://ftp.nasa.proj.ac.il/pub/taumm5/.
The MM5 data files are in GrADS format, with the data in a file with suffix .grd and the control file with the same name as the data file and with a suffix .ctl.
ISA-MEIDA holds both coarse grid data and fine grid data.
For more information see the README file.

We request that when publishing data or results using the MM5 data, an acknowledgement be given as follows:
TAU weather forecasts were developed with the weather prediction system developed at the Weather Research Center (TAU WERC) and provided by ISA-MEIDA (http://nasa.proj.ac.il/).



The MM5 model at Tel Aviv University Weather Research Center (TAU WeRC)

Principal Investigators: Prof. Pinhas Alpert, Dr. Shimon Krichak

Researcher, coordinator: Melina Dayan

Researchers: Dr. Pavel Kishcha, Karin Prezman

TECHNOLOGICAL ELEMENTS OF THE SYSTEM

For operational history and improvements to the system over time see the list of updates and improvements

The developed system includes the following two independent technological elements:

ASSIMILATION SYSTEM

 Tel Aviv University Objective Analysis and Forecast Data Retrieval and Assimilation System allowing using the NCEP global objective analyses and forecasts as the initial and driving boundary conditions. The data presently in use are for the region 30 W - 60 E; 0 - 90 N. Horizontal resolution of the data - 1.25 deg. (about 100 km). The vertical resolution - 10 isobaric surfaces (1000, 850, 700, 500, 400, 300, 250, 200, 150, 100 and 70 hPa). The forecast data from the NCEP global model are available with the same spatial resolution for every 6-hour time interval up to 48 hours.

FORECAST MODEL

The following configuration of the MM5 mesoscale model (http://www.mmm.ucar.edu/mm5/mm5-home.html) is adapted for real time NWP runs at TAU. The model uses two grids (58x73 and 73x73; 60 and 20 km grid intervals) and 36 (since January 10, 2002) atmospheric layers.

Terrain and land-use parameters are determined from the 5 min (~9 km) and 2 min (~4 km) grid intervals. The MM5V3-4 MM5V3-5 systems are adapted. Appropriate computational tools and parameterization methods of the sub-grid scale processes were selected for the weather prediction purposes. The lowest model layer is of about 25 m.

The following physical options are incorporated:

  1. Explicit moisture prediction:
    Cloud and rainwater fields predicted explicitly using the simple ice phase microphysics (Dudhia). In this scheme cloud and rainwater fields are predicted explicitly with microphysical processes. Ice phase processes are also included without using additional memory. No super-cooled water is allowed and snow is considered as immediately melting once below freezing level.

  2. Cumulus parameterization:
    1. Convective processes for the coarse resolution domains (> 30 km grid sizes) are described with the Betts-Miller scheme. The scheme is based on relaxation adjustment to a reference post-convective thermodynamic profile over a given period. No explicit representation of the downdrafts is performed.
    2. Convective processes for the higher resolution grid domains are described with Grell's cumulus parameterization scheme. The scheme is based on s computation of the rate of destabilization of quasi-equilibrium. This is a simple single-cloud model scheme with updraft and downdraft fluxes and compensating motion determining heating/moistening profile. The scheme is useful for small grid sizes of 10-30 km. The scheme tends to allow a balance between resolved scale rainfall and convective rainfall. Shear effects on precipitation are considered.

  3. The MRF (Medium Range Forecast) type planetary boundary layer parameterization. This is a simple formulation of the boundary layer developed for use in large-scale models and other situations where simplicity is required. The formulation is suited for use in models where some resolution is possible within the boundary layer, but where the resolution is insufficient for resolving the detailed boundary-layer structure and overlying capping inversion. Surface fluxes are represented in terms of similarity theory while turbulent diffusivities above the surface layer are formulated in terms of bulk similarity considerations and matching conditions at the top of the surface layer. The boundary-layer depth is expressed in terms of a bulk Richardson number, which is modified to include the influence of thermals.

    Since the 1970's, there has been a growing recognition, supported by recent work on coherent structures, that large eddies (of size on the order of PBL depth) carry most of the turbulent fluxes within the bulk of the convective PBL. Thus, relating vertical flux of a quantity to its local vertical gradient as if transport were by simple diffusion (e.g., K theory in which e.g., the momentum flux is expressed as a function of U - mean wind speed) is not strictly correct. It is more correct to consider the transport within the convective PBL to be non-local. This recognition has led to development of numerous nonlocal closure models .

    An alternative to conventional K theory is to assume that the flux can still be related to the vertical gradient, if one adds a correction term allowing for counter-gradient flux. In the MRF PBL the added counter-gradient term is proportional to the surface heat flux, and also generalized it to include top-down and bottom-up asymmetry. Attention is devoted to the interrelationship between predicted boundary-layer growth, the turbulent diffusivity profile, counter-gradient heat flux and truncation errors.

  4. 5-layer soil model with temperature prediction in 1,2,4,8,16 cm layers with mixed substrate below using vertical diffusion equation.

  5. Surface fluxes.

  6. Surface temperature prediction.

  7. A cloud-radiation scheme taking into account long- and short-wave interactions with clouds and clear air. The scheme provides surface radiation fluxes.

The developed system includes tools for verification of the model results. The technology also includes a special software for graphical representation of the model results. These use the GrADS graphical software package developed at COLA.

Last update : 07 October 2007