1. ATMS 373C.C. Hennon, UNC Asheville Observing the Tropics

2. ATMS 373C.C. Hennon, UNC Asheville Buoys Two types –Drifter Attached to sub-surface anchor (“drogue”) 15 meters below surface Drogue can measure mixed layer currents Floats freely on water surface Average lifespan is 400 days Weigh between 44 and 100 lbs. Data transmitted to passing satellites –ARGOS

3. ATMS 373C.C. Hennon, UNC Asheville http://www.aoml.noaa.gov/phod/dac/gdp_drifter.html Surface Float Drogue

4. ATMS 373C.C. Hennon, UNC Asheville http://www.aoml.noaa.gov/phod/graphics/dacdata/globpop.gif

5. ATMS 373C.C. Hennon, UNC Asheville

6. ATMS 373C.C. Hennon, UNC Asheville Buoys Two types –Moored Anchored to sea floor Generally located near coastlines Provide important information for landfalling TCs Data collected and monitored by National Data Buoy Center (NDBC)

7. ATMS 373C.C. Hennon, UNC Asheville Buoy regions controlled by the National Data Buoy Center

8. ATMS 373C.C. Hennon, UNC Asheville TAO Array – Detection and observation of ENSO events - Consists of 70 buoys

9. ATMS 373C.C. Hennon, UNC Asheville

10. ATMS 373C.C. Hennon, UNC Asheville http://www.oc.nps.navy.mil/webmodules/ENSO/TAO.html

11. ATMS 373C.C. Hennon, UNC Asheville Hurricane Katrina Passage over moored buoy GDIL1

12. ATMS 373C.C. Hennon, UNC Asheville Katrina just 65 miles to the west (145 mph) Significant wave height = 16.9 m (55.5 ft) Maximum wave height (statistically derived) = 32.1 m (109 ft)!! SWH = Average of highest 1/3 of waves

13. ATMS 373C.C. Hennon, UNC Asheville Reconnaissance Flights Aircraft penetrations of TCs Performed since 1944 GPS Dropsonde most critical instrument –measures temperature, humidity, pressure, winds –data available in near-real time at National Hurricane Center

14. ATMS 373C.C. Hennon, UNC Asheville http://www.gsfc.nasa.gov/gsfc/earth/pictures/camex4/dropsonde.gif

15. ATMS 373C.C. Hennon, UNC Asheville “Hurricane Hunters” 53 rd Weather Reconnaissance Squadron –Keesler AFB, Biloxi MS –10 C-130 planes

16. ATMS 373C.C. Hennon, UNC Asheville

17. ATMS 373C.C. Hennon, UNC Asheville Tropical Rainfall Measurement Mission (TRMM) First space-borne precipitation radar Measures precipitation between 35°N and 35°S Used for a lot of purposes –surface soil moisture –lightning research –detection of Madden-Julian Oscillation –improving SST datasets

18. ATMS 373C.C. Hennon, UNC Asheville Tropical Rainfall Measurement Mission (TRMM) “Active” sensors –Precipitation Radar (PR) “Passive” sensors –TRMM Microwave Imager (TMI) http://www.atmos.washington.edu/~houze/RAHouzeWebsite/houze_files/trmmsat.gif

19. ATMS 373C.C. Hennon, UNC Asheville TRMM and Tropical Cyclones TMI used to identify circulation centers that may be obscured in IR imagery PR provides information about rain rate

20. ATMS 373C.C. Hennon, UNC Asheville TRMM pass over Tropical Cyclone Manou. The inner swath (PR) shows rainfall rates (red = highest); the outer swath (TMI) detects rainbands, and can also be used to detect circulation centers. TMI pass near landfall of the 2004 Brazilian hurricane. Red areas represent strong convection. The center of the circulation is noted with an arrow.

21. ATMS 373C.C. Hennon, UNC Asheville QuikSCAT Scatterometer –Emits pulse of radiation (13.4 GhZ) toward ocean surface –Capillary waves (1 cm) on ocean surface backscatter pulse –More roughness = higher surface wind speeds –Wind direction can be determined by varying the azimuthal “look angle” Observe same spot from at least 4 angles

22. ATMS 373C.C. Hennon, UNC Asheville 900km 53 deg 803 km 46 deg QuikSCAT Operation

23. ATMS 373C.C. Hennon, UNC Asheville

24. ATMS 373C.C. Hennon, UNC Asheville Uses of QuikSCAT Able to retrieve high resolution (25 or 12.5 km) 10-meter wind speed and direction Cross swath width of 1800 km 90% global coverage daily Accurate within 2 m/s for wind speeds of 2-20 m/s (~4 - 40 kt) Data are assimilated in global weather models and have made them more accurate Have helped TC forecasters identify tropical depressions and maximum extent of wind Identify ITCZ and other tropical wind features

25. ATMS 373C.C. Hennon, UNC Asheville TD-14 (2003). QuikSCAT resolves circulation center that is not apparent via any other means.

26. ATMS 373C.C. Hennon, UNC Asheville Limitations of QuikSCAT Unrealistic wind directions for TCs and other rainy areas Egregious wind speed errors in rainy regions Areas of ocean missed in between swaths

27. ATMS 373C.C. Hennon, UNC Asheville Rain Impacts on QuikSCAT Data Rain contaminates the QuikSCAT data: –Attenuates beam (lowers retrieved wind speed) –Increases backscatter of the beam (raises retrieved wind speed) –Splash drops on surface enhance backscatter (raises retrieved wind speed) What’s more important? –Depends on rain rate and true surface wind speed

28. ATMS 373C.C. Hennon, UNC Asheville NHC Winds = 140 kt. MSLP = 932 mb QuikSCAT surface winds Hurricane Isabel (2003)

29. ATMS 373C.C. Hennon, UNC Asheville Advanced Microwave Sounding Unit (AMSU) Passive Radiometer Onboard polar orbiting NOAA satellites Senses microwave radiation Can determine atmospheric temperatures for many layers –15 different channel sensors –Soundings Used to diagnose warm cores in TCs and TC intensity

30. ATMS 373C.C. Hennon, UNC Asheville