IMPACT OF

OCEAN OBSERVATIONS

ON HURRICANE IRENE

INTENSITY FORECASTS

S. Glenn, O. Schofield,

J. Kohut, H. Roarty, J. Kerfoot,

M. Oliver, H. Seim, G. Seroka,

L. Palamara, L. Bowers,

R. Dunk, M. Crowley,

W. Boicourt, W. Brown,

L. Atkinson

U..

Cape Cod

Cape Hatteras

NJ

MA CT

VA

DE

NY

NC

RI

MD

PA 10 States

MIDDLE

ATLANTIC

REGIONAL

ASSOCIATION

COASTAL

OCEAN

OBSERVING

SYSTEM

1000 km Cape to Cape

Gliders Forecasts L-Band X-Band CODAR

Regional Association –

2004

Regional Coastal Ocean

Observing System – 2007

Satellite SST Products • Real-Time Global (RTG)

– 1/12 degree (~9.25 km)

– Most recent 24 hrs of in situ (buoys, ships) and satellite (AVHRR and METOP) data

Gemmill et al. (2007)

Satellite SST Products • Short-term Prediction Research and Transition Center (SPoRT)

– 1 km resolution

– Previous 14 days (weighted) of MODIS, AMSR-E, GOES/POES, OSTIA

Haines et al. (2007)

AVHRR+SPoRT Composite

• AVHRR declouding algorithm specific to Mid-Atlantic Bight, summer (for now)

– <10°C removed (cloud)

– near IR albedo >2.3% removed (clouds)

– Other tests on changes (within ~3km X 3km grid boxes) of SST (1°C) and near IR albedo (0.15%)

• 3-day AVHRR coldest pixel composite

• Then, coldest pixel composite with SPoRT

AVHRR+SPoRT Composite Example

Existing Product

New Product

39.5N 73W Surface Current Time Series

Total Current Near-Inertial Current

Wave & Wind Direction Time Series

Hurricane Irene

Hurricane Irene

Direct Wind Forcing Inertial Response

Two Gliders

Deployed by MARACOOS

in Hurricane Irene

RU16

• Deployed for EPA.

• Map bottom dissolved

oxygen.

• Provided data on

mixing during storm.

RU23

• Deployed for MARACOOS.

• Map subsurface T/S

structure for fisheries.

• Damaged early - drifter

• Recovered by fisherman

• Provided data on inertial

currents during storm.

14

33

29

105

60

salinity

% oxygen

temperature 55

55

0

0

55 depth

depth

depth

8/12 9/07 date

26 0

Hurricane Irene Hurricane Irene

Temp. Vert. Vel. Temp. Vert. Vel. Temp. Vert. Vel.

RU16

Temp.

Section

Upcast

Downcast

For Each 2-hour Segment:

1) Calculate the Average

Temperature Profile

2) Calculate the Vertical Velocity

Standard Deviation Profile and

Smooth Vertically.

Pre-Irene During Irene Post-Irene

Temp

S.D. w’

Time History of Mixing During Irene:

Profiles of the Standard Deviation

Vertical Velocity Profile

Time Progresses from Red to Blue

Temp

S.D. w’

Time History of Mixing During Irene:

Profiles of the Standard Deviation

Vertical Velocity Profile

Time Progresses from Red to Blue

Eddy viscosity

Linear

Linear * Exponential Decay

Glider RU16

Thermocline Depth

Surface Temp

Max S.D. w’

Max S.D. w’ Depth

Glider, CODAR &

Calculated Bottom Currents

NDBC Waves Bottom Orbital Velocity

NDBC Winds

MARACOOS Network Observations:

Hurricane Irene

3540455055606570758085

Win

d S

peed

(kts

)

Date

Maximum Sustained Wind Speed (10m)

NHC Best Track

NHC Forecast

RU-WRF

Atmospheric

Forecast Model

NHC Best Track

Even coupled models (e.g. HWRF) overpredicted Irene

27/120028/0600 28/060029/0600

WRF Model Run: SST Update

WARM (RTG only) COLD “Update” (AVHRR)

Run Comparison

Maximum Wind Speed Error (knots)

Date/Time (UTC)

NHC Intensity Forecast

RU-WRF Warm SST (RTG) only

RU-WRF Warm SST (RTG) + OML Model

RU-WRF Cold SST (RTG+SPoRT+ AVHRR)

27/1200 5 -17.22 -17.23 -6.17

27/1800 10 4.1 4.2 5.88

28/0000 10 1.39 -2.14 3.96

28/0600 5 -1.2 -1.04 -1.21

28/1200 15 2.39 4.79 0.5

28/1800 15 4.97 3.51 -2.67

29/0000 15 3.62 1.93 -0.89

29/0600 10 10.48 9.84 4.52

Sum of Squares 800 457 452 118

RMSE 9.43 7.13 7.09 3.61

Wind Speed Error

Date/Time (UTC)

NHC Forecast

Warm (RTG only)

Warm (RTG only, OML Model)

Cold “Update” (AVHRR)

27/1200 5 -17.22 -17.23 -6.17

27/1800 10 4.1 4.2 5.88

28/0000 10 1.39 -2.14 3.96

28/0600 5 -1.2 -1.04 -1.21

28/1200 15 2.39 4.79 0.5

28/1800 15 4.97 3.51 -2.67

29/0000 15 3.62 1.93 -0.89

29/0600 10 10.48 9.84 4.52

Sum of Squares 800 457 452 118

RMSE 9.43 7.13 7.09 3.61

• U.S. IOOS interactive network helps close a gap in storm science.

• Coastal surface & bottom boundary layer interactions influence mixing.

• The resulting cooling occurs rapidly during the peak in the storm waves.

• Cooler sea surface temperatures reduce hurricane forecast intensities.

• U.S. IOOS can help produce better hurricane forecasts now.

Hurricane Irene - U.S. IOOS as it is designed – A multi-agency activity.

Make Observations > Advance the Science > Improve the Forecasts