Remote Sensing of the Oceans:

An Indian Perspective

Ocean Society of India OSICON’13, Indian Institute of Tropical Meteorology , Pune , Nov. 26-28, 2013

Prakash Chauhan

Space Applications Centre,

Indian Space Research Organisation

Ahmedabad

Why study the Ocean ?

• Ocean State Forecasting

• Numerical Weather Prediction – Monsoon

• Ocean Resources - Living and Non-living

• Monitoring of Coastal and Ocean Environment

• Ship Routing, Navigation

• Climate change and Simulation Modeling

Seasonal monsoons & its variability

Severe weather events & cyclones (Average 5 cyclones

per year)

Intra-seasonal(30-60day) variations

Inter-annual variations: the Indian Ocean Dipole

Decadal variability and warming trends

Ocean circulations and biogeochemistry

Phailin

Ocean circulations

Indian Ocean is the poorly sampled region of the tropics

Indian Ocean Science Drivers

Space Observations : Unique Advantages

Wavelength Regions & Oceanic Parameters

Variable Wavelength Range &

Sensors

Spatial Scale Interaction Mechanism

Ocean

Colour

Visible Radiometers

(0.4 – 0.8 mm)

250m – 1Km Absorption & Scattering of Sun light

by Sea constituents

Sea Surface

Temperature

(SST)

Infrared Radiometers

( 3.0- 12.0 mm) &

Microwave Radiometers

( 4 -11 GHz)

1.0- 4.0 Km

25 Km

Emitted IR and Microwave radiation

Ocean

Winds

Microwave Scatterometrs

13.5 GHz

12- 50 Km Measure of Sea Surface Roughness

translated to wind speed & direction

Ocean

Surface

Topography

Microwave Altimeters

5- 36 GHz

8-20 Km Ranging of reflected microwave pulse

Sea Ice Visible Radiometers

Passive Microwave Rad.

1- 25 Km Reflected light in visible

Microwave emission

Sea Surface

Salinity

Passive Microwave

Radiometers ( 1.43 GHz)

50 Km 1.43 GHz frequency is sensitive to

salinity changes in sea water

Virtual Constellations for Ocean Data

• Ocean Surface Topography

• Ocean Surface Winds

• Sea Surface Temperature

• Ocean Colour Radiometry

Ocean Remote Sensing –International Scenario

Ocean Colour Instruments

NASA-MODIS

ESA-MERIS

ISRO-OCM

NOAA-VIIRS

ISRO’s Tradition of Exploring Earth and Beyond

Thematic Series

LAND RESOURCES

Integrated Indian Ocean Observing System

Past

Satellite Variables

Bhaskara

SAMIR

Ocean State, Water Vapour, Liquid water

content

Oceansat-1 Ocean Colour, Chlorophyll, Ocean

Sediments (OCM), SST, Surface Winds

(MSMR)

Present

Oceansat-2

SARAL/Altika

INSAT-3D Imager

Ocean Colour, Chlorophyll, Ocean

Sediments (OCM-II),

Surface wind (Scatterometer), Sea Ice

Sea Surface Wind

Sea Surface Height, Currents

SST

Future

Oceansat-3

GISAT

Ocean Scat

Ocean Colour,SST

Ocean Colour, SST

Surface Winds

(Space Based & In-Situ Long-term Observation Network)

In-situ MeasurementsSatellite Systems

Oceanographic

Ship cruises

(a) (b)

Cal/Val sites

Oceansat - 2 : Payloads

Ocean Color Monitor -2

• Band 765 nm 740 nm to

avoid O2 absorption

• Band 670 nm 620 nm for

better quantification of

suspended sediments

• Ku-band 13.515 GHz

• Spatial res., 50 km

• Ocean surface wind speed

from 4 m/sec to 24 m/sec

ROSADCG(M&R

)

DACS(M&R

)

PLC(R)

RECEIVER(M&R

)

DCG(M&R

)

DACS(M&R

)

PLC(R

)

DCG(M&R

)

DACS(M&R

)

PLC(R)

RECEIVER(M&R

)

DCG(M&R

)

DACS(M&R

)

PLC(R

)

Pencil Beam Scanning

Scatterometer • Frequency of operation - LI & L2 of GPS

• Codes used - C/A and P code

• Horizontal resolution - 300 Kms

• Vertical Resolution - 0.3 Kms (lower

Troposphere)

1 – 3 Kms (high

Troposphere)

• Accuracy - 1K for Temperature

- 10 % or 0.2 g/Kg for

Humidity

Mesoscale Oceanography using SARAL/Altika

INSAT-3D for Atmospheric & Ocean Observation

6 Channel IMAGER

Spectral Bands (µm)

Visible : 0.55 - 0.75

Short Wave Infra Red : 1.55 - 1.70

Mid Wave Infra Red : 3.70 - 3.95

Thermal Infra Red – 1 : 6.50 - 7.10

Thermal Infra Red – 2 : 10.30 - 11.30

Water Vapour : 11.30 - 12.50

• Resolution : 1 km for Vis & SWIR

4 km for MIR & TIR

8 km for WV

Spectral Bands (µm)

Short Wave Infra Red : 6

Mid Wave Infra Red : 5

Long Wave Infra Red : 7

Visible : 1

Resolution (km : 10

19 Channel IR SOUNDER

Ocean Surface Winds (OCEANSAT-2 Scatterometer)

• Ocean Surface winds provides momentum to ocean

circulation.Winds also impact oceanic surface currents

• OCEANSAT-2 Scatterometer is operationally providing

Global Ocean surface wind vector with in 3 hrs

• NRT global winds at 50km resolution are used by ocean

and atmospheric community

• High resolution wind product at 12.5 km scale

developed

Winds from OSCAT (a) standard wind product (50 km) and (b)

High-resolution-wind as value-added product for Thane Cyclone

Prediction of Global Tropical Cyclogenesis using OSCAT

Data

(Average Lead Time = 96 H)

Cyclone

Name

Formation

Time

(mm/dd/hh)

Prediction

Time

(mm/dd/hh)

Prediction

Lead Time

(hours)

EMILY 08/01/23Z 07/28/13Z 104

HARVEY 08/19/18Z 08/15/17Z 97

IRENE 08/20/23Z 08/19/15Z 32

KATIA 08/30/09Z 08/26/09Z 91

LEE 09/02/18Z 09/01/18Z 24

MARIA 09/06/21Z 09/04/00Z 69

NATE 09/07/21Z 09/05/18Z 51

OPHELIA 09/21/03Z 09/12/14Z 205

Cyclone

Name

Formation

Time

(mm/dd/hh)

Prediction

Time

(mm/dd/hh)

Prediction

Lead Time

(hours)

MUIFA 07/28/00Z 07/26/03Z 45

MERBOK 08/03/12Z 08/01/03Z 57

FERNANDA 08/16/15Z 08/12/19Z 92

GREG 08/17/06 08/12/04Z 123

ROKE 09/13/18Z 09/09/03Z 111

SONCA 09/15/12Z 09/14/02Z 34

HILLARY 09/21/18Z 09/14/18Z 167

HAITANG 09/25/06Z 09/20/04Z 122

EMILYHARVEY

IRENE KATIALEE

MARIA

NATE

MUIFA

MERBOKHAITANG ROKE

HILLARY

GREGFERNANDA OPHELIA

SONCA

Peak Intensity

achieved by TC

after formation

Tropical Storm

Hurricane-1

Hurricane-2

Hurricane-3

Hurricane-4

Hurricane-5

9-10-2013 (Noon) 09-10-2013 ( Mid Night)

Cyclogenesis for Cyclone Phailin using OSCAT

10-10-2013 ( Mid Night)

11-10-2013 ( Mid Night) 12-10-2013 (Noon)

Wind Speed

Advance forewarning

of cyclones using

OSCAT data

based on

Cyclogenesis studies

Severe Cyclonic storm LEHAR

Captured by OSCAT, INSAT-3D

INSAT-3D Imager

25-11-2013 1600 hrs

Cyclone Phailin: As Seen by SARAL/Altika

( Significant Wave Height)

Before Cyclone During Cyclone

3rd to 7th October, 2013 8th to 12th October, 2013

Ocean Currents

OSCAT & Altimeter derived ocean currents

Ocean Surface Currents (m/s) derived from satellite

Observations for October 12, 2013.

(a) (b)

N1

N2

N3N4N5

F1F2

F5

F3

F4

Climatic (1979-2002) maximum SIE

OSCAT derived Sea Ice Extent (SIE)

Land-ice-ocean contamination mask

Sea ice extent overlaid on the OSCAT data

(a) November 2009 spring month and (b) February 2010, a summer month.

Regions marked by N1 to N5 and F1 to F5 denote some important Antarctic

sectors experiencing changes

November 2009 February 2010

Basis:

Sigma-0,

APR

(NO GR?)

Algo-AS-OSAlgo-AS-OS

OSCAT +

OS/AS GR

3-10 10-15 15-20 20-25 >25

Melting Index

MI = Σ (σw - σsi)Where, σw =Winter Average winter

Sigma-0 (Match-September); and σsi =

Sigma-0 of summer months (i=

Oct,Nov,Dec & Jan)Drop in Sigma-0 is an indicator of surface melting (of snow/ice).

Hence, MI, which is an accumulated drop in Sigma-0, is an indicator of

total surface melting observed during the summer period

Data used: 4.45 km

enhanced resolution

OSCAT Sigma(VV)

obtained from BYU site.

Year-to-Year Change in Antarctica Surface MeltingObserved from Oceansat-2 OSCAT Scatterometer

Image is showing the

average winter Sigma-0

MI (2012-13) > MI(2011-

12)

2011-122012-13

1

2

3

Sea Surface Temperature from Geo Platform Diurnal Variation of SST using INSAT-3D Imager data

Six Band Imager of INSAT-3D has split channel SST bands at

10.2-11.2 mm & 11.5-12.5 mm

RISAT Data RV Polarisation

June 28, 2012

Dominant wave

lengths & Directions

WL (m) Dir (deg)

115.2 0.0

158.0 354.0

86.8 356.7

139.6 0.0

182.0 350.9

179.2 346.5

Subset of the RISAT Image

2-D Ocean Wave Spectrum

by Synthetic Aperture Radar

Ocean Surface Waves

• Ocean Surface waves using RISAT-1 SAR data has

been estimated

• Two dimensional wave spectrum of RISAT SAR data

shows dominant wavelengths and direction

• Algorithms for Significant wave height (SWH) using

altimeters have been developed

16.2 0

130

110

90

70

Wavelength

(meters)

Ocean Surface Waves using RISAT-1 SAR data

& Coastal Bathymetry

Island Wake effect detected

using RISAT-1 FRS Data over

Waya Island, Fiji, Pacific Ocean

Little Islands Big wakes

Island wakes

RISAT-1 FRS DATA VV

28-8-2012

• Waya Island in Fiji is a volcanic

feature having max. height of

1300 ft

• Such feature obstructs wind flow

on the Lee ward side

• The surface roughness reduction

on the Lee ward side is captured

in RISAT-1 FRS data

• This ocean-atmospheric

process is called Island wake

effect

Island wakes around

Hawaii

Waya Island

Hawai

RISAT20 Aug 2012

Sea Surface Salinity & Fresh water Flux

• Inputs on fresh water flux in ocean model

enhance prediction of ISV of SSS

• Satellite derived precipitation estimates

improves ocean model predictability

• Efforts are being done to validated SMOS

and Aquarius data for Indian Ocean region

R² = 0.791

30

32

34

36

38

40

30 32 34 36 38 40

AQ

UA

RIU

S S

SS

(p

su

)

ARGO SSS (psu)Annual Averaged SSS (psu) from Aquarius

Salinity image of Aquarius

Ocean State Forecast models at NODPAC, Indian Navy

Biological Oceanography

• ISRO has launched two Ocean Colour

Monitor (OCM) sensors

• Algorithms for atmospheric correction

of bio-optical algorithms developed

• Ocean Colour data is operationally

used to asses marine living resources,

primary productivity, algal bloom

detection and bio-physical coupling

studies

OCM – Global Area Coverage (GAC)

July-2012 OCM2 destriped nLw -443 nm MODIS (July 2012) nLw (4km) -443 nm

Global

Coverage

in 8 days

Global Data by OCM : Coral Reefs of Bahamas

03APR2012

05JUN2012

Great

Barrier Reefs

Australia

Space Based Potential Fishries Forecast

• Oceanic fronts are associated with zones of

elevated primary and secondary productivity

and fishery grounds

• Upwelling zones, eddies and rings are

known to be rich in nutrients leading to higher

productivity

• Persistence ocean features are relatively

good for fishing for longer duration

• PFZ activity in mission mode and various

modes of dissemination

PFZ Text Page PFZ Web-GIS Page

Noctiluca Bloom

Remote Sensing for Algal Blooms

Extensive Noctiluca bloom

March 2008

OCM-2

10 Feb 2010

Arabian Sea

Goa

Trichodesmium

Bloom

•Ocean Colour Data from OCM and

MODIS has been used to Monitor

Noctiluca Bloom in Arabian Sea

• Nitrogen fixing Trichodesmium

bloom in the Arabian Sea occurs in

April-May

• This bloom is captured using

Ocean colour data

• Oceanic Primary Production is important for

ocean carbon cycle, carrying capacity of marine

eco-system & climate-change studies

• Operational column primary production

estimates are generated using OCM data

• New production using satellite PP images and

modeled f-ratio based on in-situ data

• Bio-geographic provinces identified for carbon

source and sinks

Ocean Primary Productivity

mgCm-2 d-1

New ProductionEuphotic Production

100 500 1000 1500 2000 50 100 150 200 300 400 600 1000

Bio-Geographic Provinces of the Arabian Sea

Primary Productivity map

Northern Indian Ocean

Cyclone Induced

Ocean Productivity

Cyclone Phailin

Capture by

OCEANSAT-2 OCM

Satellite Gravity using Altimeter

Subsurface Modeling over Sumatran

Earthquake Region

seamounts

Identification of new seamounts and paleo-propagators in

Arabian Basin

• Satellite Altimeter

data over oceans

have been used

for Gravity

Anomaly

• Sea Mounts and

Paleo-propagators

have been

identified

OCM -2 & OSCAT

Using Kavaratti site (in-situ) data

Vicarious Gain Coefficients computed from site

using RT Model

Lunar Calibration

Comparison of sensor measured with modeled

Lunar surface radiance for Highland, moon-disc and

mare soil targets

Geo-physical product validation

Using Kavaratti, coastal and Aeronet-OC sites

Calibration of OSCAT º

Saral/Altika – Tide gauges being installed

Development of Land site

Thar & Kutch sites identified using HySI & Multi-date

LISS-3

Site characterization initiated

Megha-Tropiques

Micro rain radar & Disdrometer installed at Kavaratti

Calibration/Validation

Activities Kavaratti

AWSMicro Rain

Radar

Disdrometer

Radar

Gauge

Cyclone detection and prediction Extended range prediction for (15-day ahead)

cyclogenesis and cyclone tracks with Multi-

model approach

GIS based cyclone analysis system &

SCARPIO web portal

Image-based nowcasting ofUttarakhand Heavy Rain

MOSDAC Portal for Atmospheric & Ocean Data Dissemination

MOSDAC : NEW VERSION RELEASED

Data Released: MEGHATROPIQUES & SARAL DATA

PRODUCTS

Validated Products released

• OSCAT VALUE ADDED PRODUCTS

• WRF FORECAST (5X5 km grid)

• KALPANA Winds & Hydro Estimator Rain

• INSAT-3D Geophysical Products

OCEANSAT-3Global Ocean Coverage

Payloads

• 13 Band Ocean Colour Monitor

• 2 Bands for SST

• Ku Band Scatterometer

Status

• PSLV Launch 2015/16

Future EO Satellites for Ocean Observation

OCEANSAT-1 OCEANSAT-2 RISAT-1 SARAL INSAT-3D OCEANSAT-3 INSAT-3DR GISAT

Ocean

&

Atm

os

ph

ere

Continuity of space observations…..

1999 2009 2015

• India contributes to science working groups of

IOCCG to enhance the science of ocean colour

• Contributions towards ocean colour data sharing

with global community

• Mission requirements for future ocean colour

sensors

• ISRO is CEOS chair for 2012

• Actively contributing towards virtual constellation for

- Ocean Surface Winds (OSW-VC)

- Ocean Surface Topography (OST-VC)

- Ocean Colour Radiometry (OCR-VC)

International Ocean-Colour

Coordinating Group (IOCCG)

Committee on Earth

Observation Satellites (CEOS)

International Initiatives

• Collaboration on OCEANSAT-2 OCM &

Sctterometry

• Development of dual frequency L & S

band SAR

• Coordination on Coastal &

Ocean Applications

Challenges Ahead

• Next generation of satellite altimetry with high

spatial & temporal resolution

• Direct observations for ocean surface currents

using high frequency radars and

interferometers

•Improved coverage of SAR instruments for

operational ocean waves

•Need for high resolution SST (< 2 km) without

cloud cover for weather prediction and feature

identification

•Ocean Salinity at better spatial scales

•Continuity of space observations for long term

calibrated Climate Data Records generation

Thank You

Light reflectance ratio

865 nm

26 Oct 2009 30 Oct 2009

Plume Extent

Detection of Jaipur Oil Fire Plume using

OCEANSAT-2 OCM data