1. Impact of Sea Surface Temperature Errors on Evaporative Duct Height
LCDR Marc C. Eckardt

2. Evaporation Duct Height Model
Motivation
Evaporation Duct Height Model

3. SPY-1 Tactical Environmental Processor
IT21
Radar Data via Passive Data Tap
Radar Products
TEDS/NITES
(CVBG, ARG)
Moriah
Shipboard MET Conditions
Ducts from Surface & Rocketsonde Obs
Complements TEP Radar Measurements
TEP
AN/SPY-1
Radar “Through the Sensor” Measurements
Real-Time METOC to 200 nmi - Day and Night
Air Defense Support
NOWCAST Support
200 nmi Surface Weather
Refractivity and Duct Height
Cloud Base/Tops †
Volumetric Wind Mapping †
Real-Time Volumetric Ducting (RFC)
Radar Doctrine TDA (SEAWASP)
Chaff Evolution
Clutter Map, N-Time Around Clutter
Automated Radar Optimization † †
Low/Slow Flyers † †
CIC Displays - VDDS Feed (CO/TAO) and RSC
† = TEP Phase II
† † = TEP Phase III
Data Distribution to CVBG or ARG
via SIPRNET and TEDS

4. SPY-1/TEP Aboard USS O’KANE
Refractivity From Clutter (SPAWAR)
Hazardous Conditions
Florida
Georgia
Offshore Wallops Island, August 28, 1999
Chaff Mapping
Hurricane Dennis
August 30, 1999
Developing Chaff
Cloud
Nighttime Squall off JAX
Sept 10, 1999
Wind Mapping
Cloud Base/Tops
Air Dropped Chaff, Hawaii OPAREA
Dec 12, 1999
Winds off JAX
Sept 10, 1999
Cloud Tops/Bases
Mar 18, 1997

5. SMOOS Measurements SMOOS Upgrade
Slide 5
SMOOS
Upgrade
Hope for the Best,
Prepare for the Worst
Air Temperature; Relative Humidity (Dew Point, Wet Bulb)
Atmospheric Pressure (Station Pressure, Sea-Level Pressure, Altimeter Setting, Density Altitude, Pressure Altitude)
Relative Wind (2 sec); True Wind (1, 2 & 10 min); Shift and Gust
Vertical PTH Profile from Rocketsonde
Upper Air PTH and Winds from UMQ-12
IR Sea Temperature (automatic); Sea Water Intake Temperature
Cloud Height and Thickness (12 kft); Visibility/Precipitation
Evaporation Duct Height; Modified Refractivity Profile (near real time)
Future – IR Extinction; Rain Rate; Sea State
Note: Derived measurements are in Italics

6. REF:
_UK.PPT

7. SST Data “Main Unit” – data output every 52 seconds
Injection temp
Boom temp
Air temp
Relative Humidity
“Bow Unit” – data sampled every 5s, output every 2 min
IR sea temp
Wind speed
Manual logs - data recorded hourly IR sea temp
Handheld IR sea temp
Handheld IR sky temp
Corrected the sea temp using   Tsea = [(Tmeas4 – (1- )Tsky4)/  ] ¼

12. SST Data Conclusions IR correction can make up to a 5% difference
Accuracy of measurement ± .5° (within 1°)
Calibration and cleaning (IR) is important

13. Evaporative Duct Evaporative Duct “Height” – actually axis height
Bulk method uses
Sea surface temp
Air temp
Relative humidity
Wind Speed
Profile dependent on stability of air-sea interface
Calculated using Paul Frederickson’s model
Limited to 100 meters

14. Different Types of Ducts
300
200
100
Height (m)
Elevated Duct
Surface-based
Duct
Evaporation Duct M

15. Evaporation Duct 15 10 5 Z0
Z (m) M
RH (%)

16. Duct Height Determination:
Profile Approach
zduct at M(z) = minimum
Typical Unstable Conditions (T < 0)
Typical Stable Conditions (T > 0)
zduct= 72 m
zduct= 7 m

18. Evaporative Duct
Calculated duct height using ship injection temperature with a 0.5° STD
Compared against wind speed and relative humidity
Compared against air-sea T

22. Evaporative Duct
2nd run calculated duct height using uncorrected ship IR temperature with observed 0.644° STD
Compared against wind speed and relative humidity
Compared against air-sea T
Results not as dramatic due to higher values (+1.7 ° mean)

27. Unstable
Stable