Francesca Torricella, Vincenzo Levizzani and Miria Celano

Satellite Meteorology Group ISAC-CNR Italy

Applications of a rainfall estimation technique based on PMW and IR satellite data: assessment of reliability of instantaneous rain rate maps in the Mediterranean

Major flood event occurred on 9-10 November 2001 over the Algerian coastal zone.

Rainfall measured by rain gauges (GPCC daily data 1 x 1 degree spatial resolution)65 mm day-1 from 15:00 UTC 9 November47 mm day-1 next 24 hours

Case study

Modis RGB composite 10 November 10:45 UTC

Update histograms on receipt of new data

(PMW or IR)

The Turk’s hybrid PMW-IR method

Extract space Extract space and time and time

coincident coincident locations from locations from

IR and MW IR and MW datadata

Compute Compute RR from PMWRR from PMW

and and TTbb from IR from IR

Create statistical Create statistical relationships relationships

RR-TRR-Tbb

Assign RR at Assign RR at every IR pixelevery IR pixel

Collocating PMW and IR satellite observations

(not drawn to scale)

Allowed spatial offset needed to account for parallax-induced offsets, navigation errors, different vertical weighting by PMW and IR

Allowed time offset needed to account for hydrometeor fallout time

The hybrid PMW-IR method: the information transfer

Geostationary-based IR observation

Non-equally spaced PMW observation

How much and for how long is microphysical information from past microwave overpasses maintained?

t0

t-1t-2 t+1 etc.

time “window”

The hybrid PMW – IR technique: geolocation of TB-RR relationships

The RR values are depressed due to the smoothing process: i.e. the TB-RR relationships are averaged on 5 x 5 boxes regions to avoid discontinuities at box boundaries

Global grid for geo-locatingTB-RR relationships

Validation of rain rate fields produced Validation of rain rate fields produced by means of Turk’s techniqueby means of Turk’s technique

Validation of an Operational Global Precipitation Analysis at Short Time Scales F. Joseph Turk, Elizabeth E. Ebert, Hyun-Jong Oh and Byung-Ju Sohn, Vincenzo Levizzani, Eric A. Smith, Ralph FerraroRain gauges-RU scatter plotsfor several time average intervals(1° spatial scale)

Gauges from the AWS (Automated WeatherStation) network of the KMA (Korean Meteorological Agency)

Validation of rain rate fields produced Validation of rain rate fields produced by means of Turk’s techniqueby means of Turk’s technique

Gauge averaging time: 2 minutes window centred about the GMS observation timeAs expected all parameters improve as either the averaging period is increased or the grid size is coarsened!

0.50.5

2

09 November SSM/I rain map 19:19 [mm h-1]

09 November SSM/I rain map 19:58 [mm h-1]

TB-RR relationships for the 9 boxes (19:58)

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RU slot 00:30

10 November rain maps mm h-1

TRRM/TMI #22741 RU slot 00:30

0

TRRM/TMI #22742 RU slot 01:30

35

0

10 November rain maps mm h-1

10 November SSM/I rain map 19:05 [mm h-1]

10 November SSM/I rain map 19:43 [mm h-1]

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0TRRM/TMI #22757 RU slot 01:00

11 November rain maps mm h-1

RU slot 06:30

SSM/I 06:32

RU slot 07:00

11 November

Better accounting for parallax effects

Ground validation

Insert the new GPROF v6 PMW algorithm

For event application reduce the grid size dimension (and avoid smoothing?)

Open items…