Nowcasting SAF and INCA analyses
In this section the emphasis is put on the products based mainly on
satellite data (NWCSAF) and on the integrated analyses of
data from different measuring sources together with the NWP fields (INCA).
Nowcasting Satellite Application Facility (
NWCSAF) was developed
by
EUMETSAT member states with the aim to develop products that are
most used by forecasters for nowcasting purposes. In the following chapter some of the products,
applicable for this specific case, will be presented .
NWCSAF- CT
Cloud Type (CT) is one of the basic NWCSAF products. It gives a quick
overview of the current cloud cover by classifying clouds into 15 categories and
displaying them in different colours. The product is available during day and
night. The description of the
algorithms can be found on the NWCSAF-CT
web page.
Cloud Type product is shown in 15 minute intervals.
NWCSAF - PC
The purpose of the Precipitating Clouds (PC) product is to support detailed
precipitation analysis for nowcasting purposes. The focus is on the distinction
between non-precipitating and precipitating clouds for light and heavy
precipitation. The product gives the probabilities of precipitation intensities
in pre-defined intensity intervals. PC product is very useful for delineation of
areas with no precipitation. It gives valuable information in the area with no
radar data (temporary missing or not available) and in the area with low radar
visibility due to mountains screening, as it is illustrated in this case. The
description of the algorithms for PC product can be found on the NWCSAF-PC
web page.
Precipitating Cloud product is given in a slideshow with 15 minute interval
between the images.
NWCSAF- CRR
Convective rainfall rate (CRR) is an estimation of rainfall in
mm/h. The description of the algorithms can be found on the NWCSAF-CRR
web page. The CRR product is shown in 15 minute intervals.
INCA
( Integrated Nowcasting through
Comprehensive
Analysis) is
a nowcasting system
developed by ZAMG and used also in Environmental Agency of the
Republic of Slovenia. INCA combines different sources
of data to obtain best possible analysis of the current state of the
atmosphere and to derive nowcasting fields. As a first guess for
the state of the atmosphere INCA uses NWP fields
from the ALADIN model. Then, adding real-time data from different sources
(synop and AMP stations, radar, satellite, radisounding, AMDAR, ...) and taking into account
the laws of physics, it provides the high
resolution analyses with spatial resolution of 1 km. Analysis fields of temperature, moisture,
wind, precipitation and cloudiness are obtained. Such analyses are the base for
nowcasting up to 12h, where in the first 2 hours more weight is put to
the measurements and then gradually more and more weight is put to the NWP fields.
In the frame of this
case study INCA analyses of precipitation and wind in combination to the MOCON parameter
will be shown.
INCA
- cumulative rain rate
24 hours accumulated precipitation based on 30 minutes INCA precipitation analyses is given.
INCA - wind
analysis
Wind and MOCON parameter analyses for 06 and 12 UTC are shown.
Summary of the investigations
in this chapter
In the region where the heaviest precipitation occured, clouds were classified as
very high and high opaque with some medium clouds at the southern edge of the
cloud system. Precipitating Clouds product approved to be very
useful in the regions where radar data are missing or insufficient. Convective
Rainfall Rate highly underestimated the real precipitation amounts. However, the
indication of large amounts of precipitation is given in the right place over
the whole examined period. INCA analysis of MOCON parameter combined with the
wind field gave a good indication of convective development showing the
possibilities of using INCA in nowcasting.