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Methods

Dust forecasts

The Barcelona Dust Forecast Center (BDFC) prepares regional forecast fields using the NMMB/BSC-Dust model continuously throughout the year on a daily basis. The model consists of a numerical weather prediction model incorporationg on-line parameterizations of all the major phases of the atmospheric dust cycle.

The BDFC generates forecasts of the following set of variables:

  • Dust load (kg.m-2)
  • Dust surface concentration (μg.m-3)
  • Dust optical depth at 550 nm (-)
  • 3-hour accumulated dry and wet deposition (kg.m-2)
  • Dust surface extinction (Mm-1)

Forecasts cover the period from the starting forecast time (12 UTC) up to a forecast time of 72 hours, with an output frequency of 3 hours. They cover Northern Africa (north of equator), Middle East and most of Europe. The horizontal resolution is 10x10 km. An explanatory note is issued on the web portal when operations are stopped due to technical problems.

Forecast products are provided on this web portal 12 hours after the starting forecast time, that is, at 00 UTC.

Forecast evaluation

An important step in dust forecasting is the evaluation of the results that have been generated. This process consists of the comparison of the model results to multiple kinds of observations and is aimed to facilitate the understanding of the model capabilities, limitations, and appropriateness for the purpose for which it was designed.

A near-real-time (NRT) evaluation is performed on a monthly basis. It is assessment of how the forecast behaves relative to AERONET observations that are NRT available, allowing the modelling group and the end users to have a quick overview of the quality of the forecast.

Then, an AERONET-based quantitative forecast evaluation has been set. It yields, on a monthly, seasonal and annual basis, evaluation scores computed from the comparison of the forecasts and observations.

Archive

The  model outputs are stored, both in netcdf and in WMO FM 92 GRIB Edition 2 formats. For GRIB files, version 13.0.0 of the code tables is used:

Dissemination

The forecasts (except those of surface extinction) are disseminated in pictorial form through the WMO Global Telecommunications system. The bulletin headers are PZBcnn LEMM dd1200 where:

c=A denotes a 0-hour forecast, c=B a 3-hour forecast, ..., c=Y a 72-hour forecast

nn=01 denotes dust surface concentration, nn=02 dust optical depth, nn=03 dust dry deposition, nn=04 dust wet deposition and nn=05 dust load.

dd indicates the day

Since 5 November 2015, the forecasts are also disseminated through the EUMETCast service. EUMETCast is a multi-service dissemination system based on standard Digital Video Broadcast (DVB) technology. It uses commercial telecommunication geostationary satellites to multi-cast files (data and products) to a wide user community. EUMETCast service is managed by EUMETSAT, the European agency for exploitation of meteorological satellites. It is the European contribution to GEONETCast.

The products, covering Northern Africa, Middle East and Europe, are as follows:

- Dust Optical Depth:
Forecast of dust optical depth at 550 nm for lead times between 12 and 72 hours every 6 hours.
Example filename: 2015062412-3H_SDSWAS_NMMB-BSC-v2_OPER-OD550_DUST-12.gif

- Dust Surface Concentration:
Forecast of dust surface concentration for lead times between 12 and 72 hours every 6 hours.
Example filename: 2015062412-3H_SDSWAS_NMMB-BSC-v2_OPER-SCONC_DUST-12.gif

- Dust Load:
Forecast of columnar dust load for lead times between 12 and 72 hours every 6 hours.
Example filename: 2015062412-3H_SDSWAS_NMMB-BSC-v2_OPER-DUST_LOAD-12.gif

- Dust Dry Deposition:
Forecast of dust dry deposition for lead times between 12 and 72 hours every 6 hours.
Example filename: 2015062412-3H_SDSWAS_NMMB-BSC-v2_OPER-DUST_DEPD-12.gif

- Dust Wet Deposition:
Forecast of dust wet deposition for lead times between 12 and 72 hours every 6 hours.
Example filename: 2015062412-3H_SDSWAS_NMMB-BSC-v2_OPER-DUST_DEPW-12.gif

- Dust Surface Extinction:
Forecast of dust surface extinction at 550 nm for lead times between 12 and 72 hours every 6 hours.
Example filename: 2015062412-3H_SDSWAS_NMMB-BSC-v2_OPER-DUST_EXT_SFC-12.gif

These products are also distributed on EUMETCast Europe and Africa:

Channel: EUMETSAT Data Channel 12        
PID: 301 (Europe and Africa)
Multicast Address: 224.223.222.35

Also, they are available on the UNEP Live platform, managed by the United Nations Environment Programme, and on the WMO website (only surface concentration and optical depth).

Time-averaged values

Monthly-averaged values of dust surface concentration and dust load are computed from the daily forecasts.