The scatter diagrams below are useful to visualize how well the model is performing against measured values of sulfur dioxide and particulate matter (PM2.5). Perfect forecasts would lie along the diagnol solid black line, the further away from that line the dots get, the worse the forecast is matching observations. The numbers beside the dots show how many pairs of observations/forecasts fell at that specific point (the point below and left of the number). Stations that report fewer than 59 validated forecast points are either missing forecast data or observation data to compare with forecasts. The later is mainly due to instrument calibration.
It is important to note that, although sulfate aerosol is a forecast product, sulfate aerosol is itself not measured alone. Sulfate aerosol is measured with other smaller particles that are smaller than 2.5 micrometers (PM2.5), such as dust, sea salt, vehicle exhaust, or pollen. It is for this reason that stations not on the big island often show high measured values of PM2.5 while no vog is forecast for that area.
Click the image below to view meteograms for each location.
For a history of the VMAP model parameters click here.