7/31/2019 Poster VivianaVillamizar 10.25.12

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ASSESSMENT OF ICESat ALTIMETRY AND TIDAL GAUGE WATER ELEVATIONS WITH HYDRODYNAMIC MODEL

PREDICTIONS FOR THE CHESAPEAKE BAY

CODE 617 VIVIANA VILLAMIZAR MICHAEL F. JASINSKI

FLORIDA INTERNATIONAL UNIVERSITY, GRADUATE

OBJECTIVEThe overall objective is to assess the potential of satellite lidar to

retrieve the surface of the coastal tides during normal (non-surge)

conditions.

Specific objectives are:

1. To assess the capability of the GLAS sensor on board the ICESat

satellite platform to retrieve the spatial water surface profile during

a March 2006 transect over the Chesapeake Bay, using the 1064wavelength.

2. To validate the retrieved water levels using a calibrated, high

resolution 2D hydrodynamic model.

3. To provide insight on future altimetry observations of coastal

regions using lidar.

BACKGROUNDThe Ice Cloud and land Elevation Satellite, or ICESat, equipped with

Geoscience Laser Altimeter System (GLAS) was launched in 2002.

The ICESat sensor provided repeat along track observations for

specified reference tracks during the period 2002 -2009, with pixel sizes

of about 70 m in diameter and 170 m center-to-center spacing.

Although intended primarily to detect icecap elevation change and sea

ice, it also provided elevations over land and water bodies. Recent

studies have focused on hydrological applications including the

capability to measure coastal dynamics.

Figure 1 and 2: MIKE21 FM HD bathymetry and element grid mesh for Chesapeake Bay

MIKE 21 FM HDThe model was calibrated by DHI to account for conditions needed to

accurately model the Chesapeake Bay, where pure astronomical tide,

bed resistance, wind friction, open ocean boundary conditions, storm

surge, runoff and bottom topography are the dominant factors affecting

wave dynamics.

The MIKE 21 FM HD (Flexible Mesh Hydrodynamic Module) generates

water level variations by high resolution simulations. The model

bathymetry and grid consisted of a flexible mesh with triangular

elements ranging from 50 to 200 m as shown in Figure 1 and 2.

The tide gages along the Chesapeake Bay identified in Table 1 and

Figure 3 where used to calibrate the MIKE 21 FM HD model for water

level predictions along the Bay.

APPROACHThe present study focuses specifically on the capability to retrieve water surface

elevations of the Chesapeake Bay during a single ICESat transect in March 2006.

Validation is achieved using water surface elevations with a calibrated 2D high

resolution hydrodynamic model. This is because ICESat observations do not fall

exactly over available in situ tidal gages. Thus, it is necessary to first calibrate the

model using tide gages. Then, one can compare the ICESat elevations to those gridelements over which the satellite observations occur.

STUDY 1

NOAA TIDAL GAGE vs. MIKE 21 FM HDCalibration results are shown below during normal conditions (non-surge) from

February 24 March 12, 2006 in Figures 4 and 5. In Figures 6 and 7, results are

shown only for the first 11 days of March, 2006. These locations were strategically

chosen to include upstream and downstream gages.

-1

-0.8-0.6

-0.4

-0.2

00.2

0.4

0.6

0.81

0 48 96 144 192 240 288WaterSurfaceElevation(meter)

Time (hours)

Chesapeake Bay Bridge Tunnel 3/01/06 - 3/11/2006

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

0 48 96 144 192 240 288 336 384 432WaterSurfaceElevation(meter)

Time (hours)

Annapolis 2/24/06 - 3/12/06

Annapolis

Annapolis

MIKE21

Figure 4 and 5 compares MIKE 21s predicted water surface levels (MIKE21) fornormal conditions to NOAA verified data(red) for the Annapolis and Chesapeake Bay Bridge Tunnel gages, respectively.

Figure 6 and 7 compares MIKE 21s predicted water surface levels (MIKE21) for normal conditions to NOAA model predications

(NOAA Pred) and verified data (NOAA Verf) for the Annapolis and Chesapeake Bay Bridge Tunnel gages, respectively.

The dynamic range in the elevation of the Chesapeake Bay at time of overpass was

about 30 cm. The results provided in this study indicate that ICESat was able to

retrieve overall height and slope of the Chesapeake Bay for those areas within its

transect..

Initial Final

Transects Latitude Longitude Latitude Longitude Points

1 39.59793 -76.11258 39.58711 -76.11464 8

2 39.40284 -76.14855 39.34406 -76.15932 39

3 39.00801 -76.220851 38.98013 -76.22590 19

4 38.93677 -76.23382 38.84229 -76.25105 61

5 38.69669 -76.27744 38.64870 -76.28614 32

6 38.54650 -76.30467 38.51710 -76.30998 20

7 38.43347 -76.32509 38.22128 -76.36332 138

8 38.07567 -76.38951 38.01216 -76.40086 42

9 37.65441 -76.46480 37.61723 -76.47136 25

Table 3 and Figure 11: IC ESat Transect over Chesapeake Bay.

Figure 10: ICESat L3E Track 175

Figure 12: Compares ICESat Transect water surface elevation

over Chesapeake Bay to MIKE 21 model predictions.

Figure 13: Compares ICESat Transect water surface elevation over

Chesapeake Bay to NOAA model predictions and verified data.

Fluctuations in water levels are attributed tocombination of wave height, variations in

water surface fluctuations, bottom reflectance,

and atmospheric effects.

Results indicate difference in water surface

elevation at the Bay on the date and time of

overpass of ICESat L3E track 175 as shown by

Figure 16.

Figure 16: Contour map surface elevations over

Chesapeake Bay March 11, 2006 at 9 AM GMT.

REFERENCESMIKE21 & MIKE3 Flow Model FM. Hydrodynamic Module manual by DHI. 2011.

Chesapeake Bay Hydrodynamic Study. Kerper, Dale; Shen, Tao. DHI Water and Environment, Inc. 2011.

Li, M., Zhong, L., 2006. Tidal energy fluxes and dissipation in the Chesapeake Bay, Elsevier, Continental Shelf Research 26, 752-770.

ACKNOWLEDGEMENTSMentor: Michael F. Jasinski and colleague Jeremy D. Stoll

Research was supported by the NASA-GSFC Summer Intern Program.

Calibration of MIKE21 was carried out by DHI, Inc., San Francisco.

Table 1 and Figure 3: Tidal gages used in calibration

along the Chesapeake Bay

ID Name Latitude Longitude

8573927Chesapeake City, MD 3931.6' N 7548.6' W

8574680Baltimore, MD 39 16' N 7634.7' W

8573364Tolchester Beach, MD 3912.8' N 7614.7' W

8575512Annapolis, MD 38 59' N 7628.8' W

8571892Cambridge, MD 3834.4' N 764.1' W

8577330SolomonIslands, MD 3819' N 7627.1' W

8571421Bishops Head, MD 3813.2' N 762.3' W

8635750Lewisetta, VA 3759.7' N 7627.8' W

8636580WindmillPoint, VA 3736.9' N 7617.4' W

8638863Chesapeake BayBridge Tunnel, VA 36 58' N 766.8' W

Figure 14: Co mpares ICESat Transect 1 water surface

elevation to MIKE 21 model predictions.

y = 1.0086x-38.454

R =0.7566

y = 0.4169x-16.06

R =0.986

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.250.3

0.35

38.238.2538.338.3538.438.45WaterSurfaceElevation(meter)

Latitude

Transect 7. ICESat & MIKE21

ICESat

MIKE 21

Linear (ICESat)

Linear (MIKE 21)

y =0.7161x4 -110.73x 3 +6420.1x 2 -165404x+2E+06

R =0.6763

y =-0.1298x4 +19.536x 3 -1101.8x 2 +27602x-259165

R =0.9213-0.6

-0.4

-0.2

0

0.2

0.4

0.6

36.53737.53838.53939.540

WaterSurfaceElevation(meter)

Latitude

Transect 1-9 & NOAA Tidal Stations Chesapeake Bay

ICESatNOAA Pred

NOAA Verf

Poly.(ICESat)

Poly.(NOAA Pred)

y =0.7161x4 -110.73x 3 +6420.1x 2 -165404x+2E+06

R =0.6763

y =0.1039x4 -16.255x 3 +953.5x2 -24843x+242592

R =0.9772-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

37.53838.53939.540

WaterSurfaceElevation

(meter)

Latitude

ICESat Transect 1 - 9 & MIKE21 Chesapeake Bay

ICESat

MIKE21

Poly.

(ICESat)

Poly.

(MIKE21 )

y =-8.6862x+343.91

R =0.2702

y = 0.1753x-7.1635

R =0.9968

-0.3

-0.2

-0.1

0

0.1

0.2

39.58639.58839.5939.59239.59439.59639.59839.6WaterSurfaceElevation(meter)

Latitude

Transect 1. ICESat & MIKE21

ICESat

MIKE 21

Linear (ICESat)

Linear (MIKE 21)

Figure 15: Co mpares ICESat Transect 7 water surface

elevation to MIKE 21 model predictions.

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 48 96 144 192 240 288 336 384 432

WaterSurfaceElevation(meters)

Time (hours)

Chesapeake Bay Bridge Tunnel 2/24/06 - 3/12/06

Chesapeake

Bay Bridge

Tunnel

Chesapeake

BBTMIKE21

The good statistical agreement, as indicated by the

low RMSE values between the model elevations and

tidal gages, indicate that the model has been

successfully calibrated. Results for five tidal gages

along the Chesapeake Bay are shown in Table 2.

-0.6

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-0.10

0.1

0.2

240 244 249 254 259 264 268WaterSurfaceElevation(

meter)

Time (hours)

Annapolis - 3/11/2006

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

240 244 249 254 259 264 268WaterSurfaceElevation(meter)

Time (hours)

Chesapeake Bay Bridge Tunnel - 3/11/2006

-0.6

-0.4

-0.2

0

0.2

0.4

0 48 96 144 192 240 288WaterSurfaceElevation(meter)

Time (hours)

Annapolis 3/01/06 - 3/11/06

Figure 8 and 9 compares MIKE 21s predicted water surface levels (MIKE21) fornormal conditions to NOAA model predications

(NOAA Pred) and verified data (NOAA Verf) for the Annapolis and Chesapeake Bay Bridge Tunnel gages, respectively.

STUDY 2

ICESat ALTIMETRY vs. MIKE 21 FM HDSaturation index for data provided by NASA indicates that some recordings exceed the

limit of detector therefore analysis was performed only for specific sections within the

transects identified in Table 3 and shown in Figure 10 and 11.

CONCLUSIONThis study has shown that the ICESat sensor can observe the overall tidal profile of the Chesapeake Bay at the time of satellite overpass. Elevations of any one ICESat elevation,

however, are less certain due to a variety of instrument and environmental factors which results in higher saturation for the altimetry observations.

Overall correlation of Mike 21 model predictions and tidal gage water surface elevations was successful, thus validating the high resolution 2D hydrodynamic model as an

excellent tool for simulating coastal and estuarine hydrodynamic conditions.

Future lidar altimeters, that will provide higher vertical precision and spatial coverage, should be of significant benefit not only to hydrodynamic modelers, but also to a wide

range of applications including water resources planning, weather forecasting, ecosystem monitoring, and disaster prevention and management.

Results shown below in Figure 8 and 9 represent a close-up of MIKE 21 model

prediction for the date of ICESat overpass along the Chesapeake Bay (March 11,

2006), in comparison with NOAA tidal gage predicted and verified data.

Table 2: RMSE, Quantification of

Error for five tidal gages.

LocationRMSE

NOAA Verf NOAA Pred

Baltimore 4.808 6.456

Annapolis 1.497 2.533

Cambridge 0.770 1.431

WindmillPoint 0.549 2.036

Chesapeake BayBridge Tunnel 0.539 0.620