Overview of Sensors for Applications

Gamma Rays X Rays UV Visible NIR SWIR Thermal IR Microwave

P-band: ~0.25 – 1 GHz Microwave Region L-band: 1 -2 GHz S-band: 2-4 GHz •Sensors are 24x365 C-band: 4-8 GHz •Signal data characteristics X-band: 8-12 GHz unique to the microwave region of the EM spectrum Ku-band: 12-18 GHz K-band: 18-26 GHz •Response is primarily governed by geometric Ka-band: 26-40 GHz structures and hence V-band: 40 - 75 GHz complementary to optical W-band: 75-110 GHz imaging mm-wave: 110 – 300GHz Basic Interactions between Electromagnetic Energy and the Earth’s Surface

Incident Power reflected, ρP Reflectivity: The fractional part of the radiation, P incident radiation that is reflected by the surface.

Power absorbed, αP Absorptivity: the fractional part of the = Power emitted, εP incident radiation that is absorbed by the surface. Power transmitted, τP Emissivity: The ratio of the observed flux emitted by a body or surface to that of a P= Pr + Pt + Pa blackbody under the same condition. 푃 푃 푃 푟 + 푡 + 푎 = 1 푃 푃 푃

Transmissivity: The fractional part of the ρ + τ + α =1 radiation transmitted through the medium. At thermal equilibrium, absorption and emission are the same. Dominant mechanisms measured by sensors

1) Reflection 2) Emission

Optical cameras Radiometers LIDARs RADARs

What are passive and active sensors?

Sensors which carry their own source of illumination to measure reflection / scattering are called active sensors (LIDARs and RADARs) And, those which do not require are passive sensors (Cameras & Radiometers) EARTH OBSERVATION SATELLITES

LAND & WATER HIGH RESOLUTION OCEAN WEATHER; CLIMATE OCEANSAT-2 INSAT-3A RESOURCESAT-2, 2A CARTOSAT-2; 2A; 2B (2003) (2011, 16) (2007, 08, 10) (2009) CARTOSAT-2S KALPANA (2016, 17, 17) (2002) RISAT-1 MEGHA- TROPIQUES SARAL SCATSAT-1 RISAT-2 CARTOSAT-1 (2013) (2016) (2012) (2012) (2005) (2011) INSAT-3D (2013) INSAT-3DR (2016) 1 KM IMAGING CAPABILITY 0.8 M Microwave Remote Sensing @ SAC

Land Ocean Atmosphere Planetary

Synthetic Aperture Radar (SAR) RADIOMETERS MILLI-METER WAVE For Moon (Imaging Sensor For Land- (Used To Measure Ocean SOUNDER  Dual Frequency (L & mapping With Civilian And Parameters Like Wind Speed, Sea (Used To Measure S-BAND) SAR On Strategic Applications) Surface Temperature And Atmospheric Chandrayaan-2 Precipitation For Weather Temperature & (2017) SPACEBORNE: Forecasting) Humidity Profiles For  Ka-band Altimeter DELIVERED: Weather as Navigation and C-BAND SAR on Radar Imaging DELIVERED Forecasting) Guidance Sensor Satellite (RISAT-1) (2012) 1. SAMIR On Bhaskara-1(1978) 2. SAMIR On Bhaskara-2(1981) Temperature Ongoing .. ONGOING: 3. Microwave Scanning Microwave Sounding Unit NISAR (S-Band SAR) Radiometer (MSMR) On (TSU) For Mars RISAT-1A (Repeat of RISAT-1) Oceansat-1(1999) Humidity  P-band SAR X-BAND SAR (RISAT-2A, 2B) 4. MADRAS On Meghatrophiques Sounding Unit  Radiometer (2011) (HSU) AIRBORNE: For Venus FLOWN: SCATTEROMETERS  S-band SAR Airborne SAR (ASAR) (1992) (Used To Measure Wind  Radiometer Disaster Management SAR Velocity, On Ocean Surface  RO payload (DMSAR) – C-BAND (2005) For Weather Forecasting) L&S-band Airborne SAR (2017)

ONGOING: DELIVERED DMSAR – C-BAND 1. Ku-band Scatt onbrd Oceansat-2 DMSAR - X-BAND (2009) GB Scatt 2. Scatsat-1(2016) Ground Penetration Radar - GPR ONGOING: Oceansat-3 Scatterometer X-band SLAR – Side Looking Airborne Radar (1983-89) The ‘BASIC’ Radar

 9.6 GHZ, HH  25 KW PEAK POWER  ALTITUDE 3 KM  SWATH of 5 Kms  PLATFORM DAKOTA DC-10 (Aircraft) Synthetic Aperture Radar

•MAKES USE OF DOPPLER VARIATION BETWEEN Velocity SENSOR AND TARGET

•RESOLUTION: Rλ/2LSYN = L/2 •SAR RESOLUTION INDEPENDENT OF RANGE C-band ASAR – Airborne Synthetic Aperture Radar

The ‘BASIC’ Radar + Signal Processing for Azimuth resolution improvement = Synthetic Aperture Radar

First Flown On May 20th, 1992

Badhbasti Sabhan Kansi * * * Simra * Manlari * *Chatiriya Affected Kamrauli *Ganawli * Embankment

*Jalwara DARBHANGA Kadaria *Baliya * Rampur * *Bajrdpur Banauli *

Yaunga * Baluwahi Bharaul FLOOD INUNDATION * * *Mahnauli Panchobh * Baghia * *Ballapur LAHERIA SARAI Dih Rampur * Kamalpur * Ekmighat Baghla * * Chandih During Floods - ASAR dataTaralahi of 24* -Jul-2003* C-band Disaster Management SAR (DMSAR)

DMSAR Rack Inside The Aircraft

BEECHCRAFT DMSAR ANTENNA BEING INSTALLED AHMEDABAD AIRPORT C-band Radar Imaging Satellite

•India’s first spaceborne SAR, active array, indigenous •High resolution to wide swath modes •Polarimetry mode

HRS Mode

Resolution = 1 - 2 m, o = -16dB FRS-1 Mode

Resolution = 3 - 6 m, o = -17dB FRS1/FRS2 Mode FRS-2 Mode 536 km 536 Resolution = 6 m (circular), 6-9m HRS Mode (QuadPol), o = -20dB / -19dB MRS Mode CRS Mode Resolution = 25 m, o = -17dB CRS Mode MRS Mode Resolution = 50 m, o = -17dB Hybrid Polarimetry results

•Circular Transmit and Linear Receive (H &V) • Derivation of Stokes parameters and decomposition for target characterization

Odd bounce: BLUE Even bounce: RED Vol scattering: GREEN

Andaman Pali, Antarctica Tunisia Sea Ice Sea Rajasthan

Andaman SABARMA OIL SPILL, AHMEDABAD Sea TI NORWAY L & S-band NISAR (NASA-ISRO SAR)

•Dual frequency SAR based on SweepSAR technique. •High resolution (~6m) and wide swath (240km) simultaneously •Airborne version developed for technology demonstration and L & S-band science data generation

L & S-band Airborne SAR Airborne SAR L-band Full Pol Data •First phase of flight campaign over; more to follow @ Shoolpaneshwar forest, Narmada •Data analysis is in progress

Freeman-Durden Decomposition Image

EVEN VOLUME ODD Multifrequency Scanning Microwave Radiometer (MSMR) (1999)

6.6 GHz Sea surface Temperature 10.65GHz Wind speed 18GHz Precipitation 21 GHz Cloud Liquid water

Conical scan of MSMR antenna 43.3° and imaging geometry

11.2 rpm Oceansat-2 Ku-band Scatterometer (2009) (OSCAT)

Scatterometers measure surface backscatter cross- section with very high accuracy. 42.620

49.380

Surface roughness α wind velocity Roughness direction: max in the direction of the wind and min orthogonal to the wind Some of the Cyclones tracked by OSCAT SCATSAT-1: 2016

Thane Cyclone, India Neelam Cyclone, India Phailin Cyclone, India (28-12-2011) (31-10-2012) (11-10-2013)

Kabayan Cyclone, Phillipines Irene Hurricane, USA Sandy Hurricane, USA (01-08-2011) (27-08-2011) (29-10-2012)

• Wind speed range improved from 4 – 24m/s (OSCAT) to 3 – 30m/s (Scatsat-1) • Wind vector cell size improved from 40km x 40km (OSCAT) to 25km x 25km (Scatsat-1) • Other improvements include a host of system and operational features to improve overall accuracy. Ground Penetration Radar (GPR)

An initiative with a difference, this instrument looks beneath earth surface. 250-750 MHz stepped frequency subsurface imaging GPR is part of several expeditions to Antarctica for ice/snow studies

Sea Ice Thickness Testing Ice Sheet Thickness Testing Signatures in Optical and IR regions

•Interpretation of optical images requires knowledge of spectral reflectance signatures of various materials (natural or man-made)

Set of characteristics by which a material or an object may be identified on an image or photograph. SENSORS IN RESOURCESAT SATELLITE

LISS-IV

RESOURCESAT SENSORS Specification LISS-IV LISS-III AWiFS Instantaneous 5.8 at nadir 23.5 56 at nadir LISS-III Geometric Field of (Across Track) (Across Track) View (m) Spectral Bands B2: 0.52-0.59 B2: 0.52-0.59 B2: 0.52-0.59 (micrometer) B3: 0.62-0.68 B3: 0.62-0.68 B3: 0.62-0.68 B4: 0.77-0.86 B4: 0.77-0.86 B4: 0.77-0.86 B5: 1.55 – 1.70 B5: 1.55 – 1.70 Swath (km) 23.9 (MX) 141 740 (combined) 70 (mono) 370 (each head) AWiFS

SENSORS IN CARTOSAT SATELLITE HYPER SPECTRAL IMAGING SPECTROMETER

Hyperspectral Imaging More than 100 bands with high resolution (~5nm) closely spaced (continuum) bands

…. 100’s of parallel spectrometers

High spectral resolution spectroscopy has capability to detect sharp absorption features (which is averaged out in broad band) manifested due to composition and certain physical, chemical and biophysical condition of material AVIRIS-NG Airborne Hyperspectral Campaign In collaboration with JPL/NASA (Airborne Visible/Infrared Imaging Spectrometer – NextGen)

Airborne data acquisition over 57 sites in 84 days Radiance data is used to generate surface reflectance data in 425 bands (VNIR and SWIR – 380 to 2510nm with at 5 nm sampling) LIDAR REMOTE SENSING OF ATMOSPHERE

LIDAR: LIght Detection And Ranging LIDAR REMOTE SENSING OF VEGETATION LIDAR: LIght Detection And Ranging Thanks