In this paper we present the beneficial impact of high resolution (in
space and time) wind and temperature observations from aircraft on
very short-range numerical weather forecasting. The observations are
retrieved using the Tracking and Ranging radar from Air-traffic
Control at Schiphol Airport, the Netherlands. This enhanced
surveillance radar tracks all aircraft in sight every four seconds
generating one million wind and temperature observations per day
in a radius of 270km around the radar.

Now-casting applications will benefit from improved three dimensional
wind fields. When these observations are assimilated into a numerical
model with an hourly update cycle, the short-range three-dimensional
wind field forecasts match the observations better than those from an
operational forecasts cycle, which is updated every three hours. The
positive impact on wind in the first hours of the forecast gradually
turns into a neutral impact, when compared to other wind and
temperature observations. The timeliness of the forecasts combined with the high resolution of
the observations are the main reason for the observed nowcasting benefits.

All in all, we found the assimilation of high-resolution wind (and temperature)
observations to be beneficial for now-casting and short-range forecasts up to two to three hours.