Satellite Data AssimilationActivities at CIMSS for FY2003

Robert M. AuneRobert M. AuneAdvanced Satellite Products TeamAdvanced Satellite Products Team

NOAA/NESDIS/ORA/ARADNOAA/NESDIS/ORA/ARADCooperative Institute for Meteorological Satellite StudiesCooperative Institute for Meteorological Satellite Studies

Madison, WisconsinMadison, Wisconsin

Research / ApplicationsCollaborations.Concerns / Shortfalls.

Research and Applications…..

Tools

CIMSS Regional Assimilation System (CRAS)

First real time prediction system to use cloud and moisture products from the GOES sounders (1996)

New for FY2003:

Real time CRAS now at 61 km resolution with 20 km nest using single field-of-view (10km) GOES retrievals to initialize moisture and clouds (Raymond)

Polar stereographic version of CRAS running over Antarctica

Multi-layer cloud initialization using GOES/MODIS

Pacific CRAS for THORPEX

Retrieved Cloud Top Pressure/Effective Cloud Amount

This information can be used to initialize 3D cloud fields in numerical prediction models

600 hPa 300 hPa

50% 98%

CRAS is currently running in real time at 20 km horizontal gridspacing to study how cloud physics software responds to finerhorizontal resolution. Above (center) is a CRAS 15 hour forecastIR image valid 15UTC 06Aug01. Also shown are images of cloudtop pressure (left) and IR window from GOES at the validating time.CRAS cloud forecasts are monitored for shape and position.

Cloud top pressurefrom GOES-8 Sounder

CRAS 15 hr forecast GOES-8 IR image

36hr Forecast Time Series: Sfc T

303540

45505560

6570

17

/12

17

/18

18

/00

18

/06

18

/12

18

/18

19

/00

Day / Hour

T (

de

gF)

CRAS fcst

Avn fcst

Eta fcst

NGM fcst

Obs

Forecast Cloudtop Pressure: Madison, WI

500550600650700750800850900950

10001

7/1

2

17

/18

18

/00

18

/06

18

/12

18

/18

19

/00

Day / Hour

Pre

ss

ure

(h

Pa

)Cld Top P

GOES CTP

Forecast Bust in Madison, WI

On April 18, 2000 the official predicted hightemperature for Madison was 65 F. Persistentcloud cover kept temperatures from rising. TheCIMSS Regional Assimilation System (CRAS)was the only model that predicted overcast skieswhich resulted in a cooler forecast. Figure 1shows the forecast surface temperature from theCRAS and from the Aviation, Eta, and NGMmodels of the National Center for EnvironmentalPrediction (NCEP), initialized at 12UTC, April 17.The observed temperatures at Madison areplotted with a solid line. Figure 2 shows thepredicted cloud-top pressure from CRAS andthe observed cloud-top pressure from GOES-8.The GOES-8 sounder detected higher cloudsmoving in after 12UTC on the 18th while thelow clouds persisted The CRAS runs at 80kmresolution and uses information from theGOES sounders to initialize water vapor andclouds. Daily CRAS forecasts can be viewed at: http://cimss.ssec.wisc.edu/model/daily.html

Figure 1

Figure 2.

Using MODIS Moisture Products to Initialize Forecasts for Antarctica

Cloud-top pressure and total precipitablewater from the MODerate resolution ImagingSpectroradiometer (MODIS) are currently being evaluated in the polar version of the CIMSS Regional Assimilation (PCRAS). The data are being used to adjust mixing ratio and cloud water in the forecast model during a 24 hour forecast initialization period.Approximately 800,000 observations at 5 kmresolution were used from each of the 14satellite passes during the period. Initial andboundary conditions are provided by theNCEP Aviation model. The figure at right shows the differences in the total precipitable water (MODIS minusno MODIS) at the end of the 24 hour initialization period. For this case, valid Dec 7, 2000, the MODIS data has reduced the amount of water vapor in the coastal regions (blue areas).

24 hour CRAS spinnup forecast with mixingratio and cloud adjustments using cloud-toppressure and total precipitable water retrievedfrom MODIS valid 07 Dec 2000.

Composite IR window channel image fromAVHRR valid 07 Dec 2000.

VerificationCloud-top pressurebased on NESDIS product

Effect of GOES data on 3-h RUC cloud-top fcsts

Valid 1200 UTC 9 Dec 2001

3h 20km RUC cloud-top fcstw/ GOES cloud assimilation

3h 40km RUC cloud-top fcstNo GOES cloud assimilation

3h 20km RUC cloud-top fcstw/ GOES cloud assimilation

VerificationCloud-top pressurebased on NESDIS product

Cloud-top forecast verification - correlation coefficient between forecast and NESDIS cloud-top product- much improved cloud forecasts even at 12h28 Sept – 2 Oct 2001

40km RUC 20km RUC w/ cloud analysis

Nowcasting Analysis System

Bob Aune, NESDIS/ORA and Ralph Petersen, NWS/EMC

HYPOTHESIS: Can we design a fast objective analysis system that places emphasis on observations, not forecast model requirements?

The influence of observations must be optimized in space and time. Previous observations are projected forward in time to augment spatial and temporal coverage (GOES).

Such an analysis system would not be influenced by model initialization constraints or model forecast errors

A real time implementation would provide forecasters with fast 3D snapshots of the atmosphere.

Typical GOES-8 sounder retrievalcoverage at 12 UTC.

Coverage after forward trajectories arecomputed for three levels (300, 500, and700 hPa). Information is spread indifferent directions due to wind shear.

Statistics comparing trajectory observationsto actual equivalent potential temperature (K)retrievals from GOES-8. Observation countfor GOES-8 drops due to increasing clouds.Statistics indicate trajectory observationsretain useful information for four to fivehours. Low-level trajectory observationsdegrade faster.

700 hPa mixing ratios from GOES-8valid 12 UTC projected forward in timeand compared with corresponding GOES retrievals.

Fits remain goodthrough 3 hours.Biases increaseafter that, especially at low levels wherediurnal effects are large.

initial

+6 hours

+3 hours

The CIMSS Regional Assimilation System (CRAS) is being used to study the predictability of fog in Wisconsin. Time series plots from the 20 km CRAS are being produced for instrumented sites (blue squares) from the Wisconsin Department of Transportation surface mesonet. Plotted parameters are:

Temperature (Fahrenheit)Dew point temperature (Fahrenheit)Mean sea-level pressure (millibars)Total cloud water (millimeters * 1000)Wind barbs (speed (knots) and direction)Accumulated precipitation (inches*100)

FOG

GOES-12 Visible

At present, the Eta Data Assimilation System (EDAS) assimilates GOES sounder radiances over water, and 3-layer precipitable water (PW) over land. The difference between GOES 3x3 total PW from CIMSS and the total PW from the Eta analysis is plotted above. Red indicates Eta is too dry.

Total precipitable water differences, GOES 3x3 (CIMSS)minus EDAS analysis for 12UTC 14Mar02

GOES Sounder Radiances in the Eta?

PW differences (mm) at the end of theassimilation cycle (tm00) using oneiteration in the RTE calculation for each insert time.

Validating EDAS RadianceAssimilation against GOESTotal Precipitable WaterRetrievals

PW differences (mm) at the end of theassimilation cycle (tm00) using twoiterations in the RTE calculation foreach insert time.

Iterations used to solve RTEEDAS = 1GDAS = 2NESDIS Retrieval = 3