Satellite Data Assimilation Activities at CIMSS for FY2003 Robert M. Aune

1. Satellite Data Assimilation Activities at CIMSS for FY2003 Robert M. Aune Advanced Satellite Products Team NOAA/NESDIS/ORA/ARAD Cooperative Institute for Meteorological Satellite Studies Madison, Wisconsin Research / Applications Collaborations. Concerns / Shortfalls.

2. 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

3. Retrieved Cloud Top Pressure/Effective Cloud Amount 600 hPa 300 hPa This information can be used to initialize 3D cloud fields in numerical prediction models 50% 98%

4. Cloud top pressure from GOES-8 Sounder GOES-8 IR image CRAS 15 hr forecast CRAS is currently running in real time at 20 km horizontal grid spacing to study how cloud physics software responds to finer horizontal resolution. Above (center) is a CRAS 15 hour forecast IR image valid 15UTC 06Aug01. Also shown are images of cloud top pressure (left) and IR window from GOES at the validating time. CRAS cloud forecasts are monitored for shape and position.

5. Forecast Bust in Madison, WI On April 18, 2000 the official predicted high temperature for Madison was 65 F. Persistent cloud cover kept temperatures from rising. The CIMSS Regional Assimilation System (CRAS) was the only model that predicted overcast skies which resulted in a cooler forecast. Figure 1 shows the forecast surface temperature from the CRAS and from the Aviation, Eta, and NGM models of the National Center for Environmental Prediction (NCEP), initialized at 12UTC, April 17. The observed temperatures at Madison are plotted with a solid line. Figure 2 shows the predicted cloud-top pressure from CRAS and the observed cloud-top pressure from GOES-8. The GOES-8 sounder detected higher clouds moving in after 12UTC on the 18th while the low clouds persisted The CRAS runs at 80km resolution and uses information from the GOES sounders to initialize water vapor and clouds. Daily CRAS forecasts can be viewed at: http://cimss.ssec.wisc.edu/model/daily.html Figure 1 Figure 2.

6. Using MODIS Moisture Products to Initialize Forecasts for Antarctica Cloud-top pressure and total precipitable water from the MODerate resolution Imaging Spectroradiometer (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 km resolution were used from each of the 14 satellite passes during the period. Initial and boundary conditions are provided by the NCEP Aviation model. The figure at right shows the differences in the total precipitable water (MODIS minus no 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).

7. Composite IR window channel image from AVHRR valid 07 Dec 2000. 24 hour CRAS spinnup forecast with mixing ratio and cloud adjustments using cloud-top pressure and total precipitable water retrieved from MODIS valid 07 Dec 2000.

8. 3h 20km RUC cloud-top fcst w/ GOES cloud assimilation Verification Cloud-top pressure based on NESDIS product 3h 40km RUC cloud-top fcst No GOES cloud assimilation Effect of GOES data on 3-h RUC cloud-top fcsts Valid 1200 UTC 9 Dec 2001

9. 40km RUC 20km RUC w/ cloud analysis 3h 20km RUC cloud-top fcst w/ GOES cloud assimilation Verification Cloud-top pressure based on NESDIS product Cloud-top forecast verification - correlation coefficient between forecast and NESDIS cloud-top product - much improved cloud forecasts even at 12h 28 Sept – 2 Oct 2001

10. 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.

11. Typical GOES-8 sounder retrieval coverage at 12 UTC. Coverage after forward trajectories are computed for three levels (300, 500, and 700 hPa). Information is spread in different directions due to wind shear.

12. Statistics comparing trajectory observations to actual equivalent potential temperature (K) retrievals from GOES-8. Observation count for GOES-8 drops due to increasing clouds. Statistics indicate trajectory observations retain useful information for four to five hours. Low-level trajectory observations degrade faster.

13. 700 hPa mixing ratios from GOES-8 valid 12 UTC projected forward in time and compared with corresponding GOES retrievals. initial +3 hours Fits remain good through 3 hours. Biases increase after that, especially at low levels where diurnal effects are large. +6 hours

14. 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

15. GOES Sounder Radiances in the Eta? Total precipitable water differences, GOES 3x3 (CIMSS) minus EDAS analysis for 12UTC 14Mar02 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.

16. Validating EDAS Radiance Assimilation against GOES Total Precipitable Water Retrievals PW differences (mm) at the end of the assimilation cycle (tm00) using two iterations in the RTE calculation for each insert time. PW differences (mm) at the end of the assimilation cycle (tm00) using one iteration in the RTE calculation for each insert time. Iterations used to solve RTE EDAS = 1 GDAS = 2 NESDIS Retrieval = 3