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Diapositivo 1

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Title: Diapositivo 1 Author: Maria da Luz Last modified by: Muacho Created Date: 2/12/2011 2:35:25 PM Document presentation format: Apresenta o no Ecr (4:3) – PowerPoint PPT presentation

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Title: Diapositivo 1


1
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Sérgio Muacho - IPMA
2
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Altimetry applications for oceans and seas
  • Operational oceanography
  • (waves and wind)
  • Mean Sea Level
  • Tides
  • Ocean large-scale circulation
  • Ocean currents and eddies
  • Bathymetry
  • Tsunamis

3
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Altimetry applications for oceans and seas
here we will focus on
  • Operational oceanography
  • (waves and wind)
  • Mean Sea Level
  • Tides
  • Ocean large-scale circulation
  • Ocean currents and eddies
  • Bathymetry
  • Tsunamis

4
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Do you know other applications of altimetry? Yes
No
5
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Do you know other applications of altimetry? Yes
No
- Ice (Ice sheets Sea ice) - Climate (ENSO
NAO Decadal oscillations) - Atmosphere
(Cyclones Rain) - Hydrology land (Lake level
River level)
6
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Chapter I Introduction Jason-2 radar
http//www.eumetsat.int/Home/Main/Satellites/Jason
-2/MissionOverview/index.htm?len
7
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Some considerations about altimetry
  • Satellite does not measure individual waves
  • Satellite beam is about 1-2 km minimum in
    diameter
  • Measurements are averaged (over 1s, 7km along
    the track) to remove noise.

8
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
The radar altimeter receives the reflected wave
(echo), which varies in intensity over time. If
sea surface is flat (a), the reflected wave's
amplitude increases sharply from the moment the
leading edge of the radar signal strikes the
surface. In rough seas (b), the wave strikes
the crest of one wave and then a series of other
crests which cause the reflected wave's amplitude
to increase more gradually.
Satellite Radar wave Radar wave as seen from
above the surface Shape of the power as
received back by the onboard radar
We can derive ocean wave height from the
information in this reflected wave the slope of
the curve representing its amplitude over time is
proportional to wave height. from
http//www.altimetry.info/html/alti/principle/wave
form/ocean_en.html
9
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
How do satellite altimeters measure ocean waves?
10
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
How do satellite altimeters measure ocean waves?
  • Over ocean surface, the echo waveform has a
    characteristic shape that can be described
    analytically (Brown model)
  • The edge slope is related to the significant
    wave height (SWH)

power
time
11
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
12
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
This is an ascending or descending orbit?
Ascending Descending
13
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Can we use altimetry data in an operation way?
Yes No
14
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Can we use altimetry data in an operation way?
Yes No
No, because the satellite goes over the same
point every cycle (10 days at least, up to 35
days depending on the satellite)
15
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Can we use altimetry data in an operation way?
Yes No
In my opinion, yes! If a satellite goes
over your region of interest (ROI), you can have
data 2 hours after the measurements. This is
relevant in oceans and sea zones with a lack of
observations (buoys), such as West Iberian coast
and more off-shore areas.
16
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
The Atlantic wave storm (17 20 April 2012)
17
Wave storm life cycle The early stages (synoptic
conditions)
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Plot surface wind gt10 m/s
Azores
18
Wave storm life cycle The early stages (synoptic
conditions)
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Plot surface wind gt10 m/s
Azores
Steady southwesterly flow with several
cyclogenesis, some of them originate deep lows
with very strong winds
19
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Wave storm life cycle The early stages (synoptic
conditions)
Omega Block between 14 and 20th april 2012 with
some minor changes in position
Azores
B
B
A
20
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Wave storm generation and propagation
Adapted for http//www.co.fc.ul.pt/
21
Wave storm propagation (03UTC 17 April-12)
model results (WAM/ECMWF) and Jason-2
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
22
Wave storm propagation (17 and 18 Apr 2012)
model results (WAM/ECMWF)
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
23
Approaching shore in Bay of Biscay and West
Iberian coast (19 and 20 Apr 2012) model
results (WAM/ECMWF)
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
24
Lets track the storm with Jason-2!
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
25
Jason-2 data and wave model forecast (03 UTC
17-Apr)
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
26
Jason-2 data and wave model forecast (03 UTC
17-Apr)
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
27
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (03 UTC
18-Apr)
28
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (03 UTC
18-Apr)
29
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (18 UTC
18-Apr)
30
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (21 UTC
18-Apr)
31
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (06 UTC
19-Apr)
32
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Important ideas
  • We collect 5 passages during a three days period
    (17, 18 and 19 April 2012) in our ROI
  • Jason-2 data is in good agreement with wave
    model and buoys (2400 points with a mean
    difference of 3,5cm)
  • We can use altimetry information to supply the
    lack of buoys in off-shore areas (we can monitor
    sea conditions!).

33
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Important ideas
  • We collect 5 passages during a three days period
    (17, 18 and 19 April 2012) in our ROI
  • Jason-2 data is in good agreement with wave
    model and buoys (2400 points with a mean
    difference of 3,5cm)
  • We can use altimetry information to supply the
    lack of buoys in off-shore areas (we can monitor
    sea conditions!).
  • But. It is difficult to track a storm only with
    the altimetry data
  • Altimetry doesnt give you an idea of sea
    conditions in all your ROI
  • Miss important information for marine
    forecasters, such as wave direction.

34
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data against buoys data in West Iberian
coast
35
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (03 UTC
18-Apr)
º
36
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data against buoys data
1,4m 02h45m, 18-Apr
º
37
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data and wave model forecast (18 UTC
18-Apr)
º
38
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 data against buoys data
º
7,8m 17h17m, 18-Apr
39
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Additional issues
40
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 near costal regions (e.g., NW Iberian
coast)
41
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Jason-2 near islands (e.g., Azores)
North swell Wave refraction is well represented
by altimetry
42
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Update Atlantic ePort !
43
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Atlantic ePort (http//eumetrain.org)
Archive 10 April 2012 onwards
44
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
Acknowledges
Portuguese Hydrographical Institute
(www.hidrografico.pt) Spanish Hydrographical
Institute (www.puertos.es)
45
Tracking an Atlantic Wave Storm with Jason-2
Altimeter
- Thank you! -
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