COST 723 Training School - Cargese 4 - 14 October 2005 OBS 3 Radiative transfer for thermal...

COST 723 Training School - Cargese 4 - 14 October 2005

OBS 3

Radiative transfer for thermal radiation.Instruments

Bruno Carli


Table of Contents

• Space instruments

• Recent and future instruments (IMG,

ILAS, AIRS, MIPAS, TES,

HIRDLS, ACE, IASI, CrIS, GIFTS,

GGOS, REFIR)

• General considerations


Space Instruments


IMG: Interferometric Monitor for Greenhouse Gases

Agency: NASDA

Satellite: ADEOS I

Launched on 17th August 1996. Stopped on 30th June 1997.

IMG overview


IMG

IMG is a nadir-looking Fourier transform infrared spectrometer (FTIR) operating in the spectral range from 3300 - 714 cm-1 (3.3 - 14.7 µm), with a spectral resolution of 0.1 cm-1 (apodized).

IFOV=10 mrad (8x8 km2 footprint)


ILAS I and II overview

• ILAS I and II: Improved Limb Atmospheric Spectrometer

• Agency: NASDA / JAXA

• Satellites: ADEOS I and II

• ADEOS-I launched on 17th August 1996. Stopped on 30th June 1997.

• ADEOS-II launched on 10th April 2003. Stopped on 24th October 2003.


ILAS I e IIILAS is a solar occultation grating spectrometer with two gratings, one measuring in the thermal IR with 44 channels in the range from 6.21-11.77 µm (850-1610 cm-1), the other measuring in the VIS and IR with 1024 channels in the range of 0.753 - 0.784 µm.

IFOV (at tangent height) 2 km (vertical) x 13 km (horizontal).


MIPAS: Michelson Interferomer for Passive Atmospheric Sounding

Agency: ESA

Satellite: Envisat

Launched on 1st march 2002. Operating.

MIPAS overview


MIPAS is a Fourier Transform (FT) Spectrometer that measuresthe middle infrared (MIR) emission of the atmosphere at the limb.

MIPAS


MIPAS

FT

MIPAS is a Fourier Transform (FT) Spectrometer that measuresthe middle infrared (MIR) emission of the atmosphere at the limb.


• Spectral range: 685 - 2410 cm-1, = 14.6 – 4.15 m

• Spectral resolution 0,025 cm-1 unapodized• Spectral resolution FWHM 0.035 cm-1

• Vibrational spectra of molecules

MIPASMIPAS is a Fourier Transform (FT) Spectrometer that measuresthe middle infrared (MIR) emission of the atmosphere at the limb.


• Spontaneous thermal emission (blackbody) of the atmosphere

• Continuous (day and night) measurements are possible



In a limb view the line of sight (LOS) penetrate the atmosphere down to a minimum altitude (tangent altitude) and exits again to space.

A typical limb sequence is made of a set of measurements made with different tangent altitudes (typically 3 km increments).



MIPAS Functional Description


Front End Optics (FEO)

AzimuthScan Unit

Telescope

Baseplate

ElevationScan Unit


InterferometerBeamsplitter

Corner Cube


Interferometer characteristics

• Cooled instrument

• Optical compensation of alignment errors

• Double sided interferograms

• Double input and double output


O MIPAS on ENVISAT


MIPAS Observation Principle


MIPAS measurement scenario

Characteristics:

sweep duration: 4.45 s (full resolution) sweeps per limb seq.: 17 (68km, 60km, 52km, 47km, (42 – 6) km in 3 km

steps # limb seq. per orbit: ~ 75 (deep space cal. every 5 sequences) azimuth scan range: ~ +/-150

rearward geometries: global coverage, poles visible


MIPAS coverage in one orbit


MIPAS coverage in one day


MIPAS coverage in three days


-110° long66° long-85° long91° long-60° long116° long-35° long141° long-9° long166° long16° long-160° long41° long-135° long12 h measurements

0

10

ppm

5

Ozone vertical distribution as a function of latitude and longitude


8 km11 km14 km17 km20 km23 km26 km29 km32 km35 km38 km41 km44 km47 km50 km53 km8 - 53 km

0

5

10

ppm

3D global ozone distribution


AIRS: Atmospheric InfraRed Sounder

Agency: NASA

Satellite: AQUA

Launched on the 4th of May 2002. Operating

AIRS overview


AIRSAIRS is a grating nadir-looking instruments.

3 IR wavebands (from 3.74 µm to 15.4µm) with a total of 2378 channels at spectral resolution < 1cm -1.

4 Vis/NIR channels (from 0.4 µm to 1.1 µm).

IFOV 13.5km at nadir


ACE overview

• ACE: Atmospheric Chemistry Experiment

• Agency: Canadian Space Agency

• Satellite: SCISAT-1

• Launched on 12th August 2003. Operating.


ACE

ACE is a high spectral resolution (0.02 cm-1) occultation FT spectrometer operating from 750–4400 cm-1 (about from 2.2 to 13.3 µm) with a spectral resolution of 0.02 cm-1.


TES: Tropospheric Emission Spectrometer

Agency: NASA

Satellite: AURA

Launched on 15th July 2004. Operating.

TES overview


TES

TES is an infrared-imaging Fourier transform spectrometer operating in a combination of limb and nadir modes.


TES

• TES is an infrared-imaging Fourier transform spectrometer operating in a combination of limb and nadir modes.

• Spectral range 650 – 3050 cm-1 (about 3.3 – 15.4 m).

• Spectral resolution 0.02 cm-1


TES

• TES is an infrared-imaging Fourier transform spectrometer operating in a combination of limb and nadir modes.

1x16 element focal plane arrays


HIRDLS: High Resolution Dynamics Limb Sounder

Agency: NASA-UK

Satellite: AURA

Launched on 15th July 2004. Operating.

HIRDLS overview


HIRDLS

HIRDLS is a multi-channel limb-viewing infrared (IR) radiometer operating in the spectral range from 6 to 18 m


IASI overview

• IASI: Infrared Atmospheric Sounding Interferometer

• Agency: CNES

• Satellite: Metop 1, 2 and 3 by EUMETSAT

• Launch scheduled for 2006, 2010 and 2015.


IASIIASI is a nadir-sounding imaging FT spectrometer operating in the spectral range 645 to 2760 cm-1 (15.5 to 3.62 µm) with a spectral resolution of 0.25 cm-1.

IFOV=10 mrad (8x8 km2 footprint). A 2 x 2 array in each of its three bands.


CrIS overview

• CrIS: Cross-track Infrared Sounder

• Agency: NOAA

• Satellite: NPOESS (National Polar-orbiting Operational Environmental Satellite System)

• Launch scheduled for 2008.


CrIS CrIS is an imaging interfereometer with a 3 x 3 array covering 3 bands over a spectral range of 3.92 µm to 15.38 µm (650 cm -1 to 2550 cm -1 ).The instrument resolution varies from 0.625 cm-1 to 2.5 cm -1. Picture of prototype

TelescopePorchswingMechanism

Detector Dewar

Focal PlaneElectronics

Primary Structure

SceneSelectionModule

Composite Optical Bench


GIFTS overview

• GIFTS: Geosynchronous Imaging Fourier Transform Spectrometer.

• Agency: NASA

• Satellite: GIFTS-IOMI

• Launch scheduled for ?? .


GIFTSGIFTS is a geostationary, nadir sounding, imaging interferometer with a detector arrays 128 x 128, operating in the spectral ranges 685 - 1130 cm-1 and 1650 - 2250 cm-1 with a spectral resolution of 0.6 cm-1.


GGOS overview

• GGOS: Greenhouse Gas Observing Sensor

• Agency: JAXA

• Satellite: GOSAT

• Launch scheduled for August 2008.


Greenhouse Gas Observing SensorThe Greenhouse Gas Observing Sensor is a nadir-sounding FT spectrometer operating in the visible (three bands) and in the spectral range 645 to 2760 cm-1 (14.3 to 0.75 µm) with a spectral resolution from 0.5 to 0.2 cm-1. IFOV 10 km


REFIRREFIR is a nadir-sounding FT spectrometer operating from balloon in the spectral range from 100 to 1400 cm-1 with a spectral resolution of 0.5 cm-1.

Room temperature detectors. First balloon flight on 1st July 2005


Summary of recent and planned missions

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

IMG

ILAS

MIPAS

AIRS

ACE

TES

HIRDLS

IASI

CrIS

GIFTS

GOSAT

occultation nadir limb emission limb/nadir


General considerationsspectral resolutionspectral resolution

On going evolution from radiometers to multichannel grating spectrometer, and to high resolution FT spectrometers.

Data analysis is performed with either channel or microwindow selection


General considerationsemission measurementsemission measurements

Few missions use occultation measurements, which, with their high S/N, are best suited for the understanding of radiative transfer.

Most of the new mission use emission measurements, which, with their continuous and global coverage, are best suited for the understanding of atmospheric processes.

Thermal radiation


General considerationsimagingimaging

Array detectors are providing imaging capabilities to FT spectrsocpy.

IASI TES


General considerationsspatial resolutionspatial resolution

The large number of observations (both in space and spectral domain) improve the conditioning of the inversion problem.

In nadir sounding the good conditioning can be exploited for attaining 1 km vertical resolution.

In limb sounding the good conditioning can be exploited for attaining 50 km horizontal resolution.


General considerationsspacecraft orbitspacecraft orbit

Polar platforms are usually the preferred choice because of global coverage requirements.

Meteorological and now-casting applications require frequent observations from geostationary platforms.

COST 723 Training School - Cargese 4 - 14 October 2005 OBS 3 Radiative transfer for thermal...

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