satellite atmospheric science at kiruna space campus mathias milz luleå university of technology...
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Satellite Atmospheric Science at Kiruna Space Campus
Mathias Milz
Luleå University of Technology
Department of Space Science
Kiruna
The Satellite Atmospheric Science Group at Kiruna Space Campus
Head of the group: Prof. Stefan Buehler
Currently:one Ex-jobb student
four PhD students (1-2 coming this fall) three Assistant Professors
one software engineer
Young group (since fall 2006)
Close collaboration with IRF, Chalmers, Met Office (UK), Observatoire de Paris, SMHI, etc.
Focus:- atmospheric humidity- cloud ice- radiative transfer
http://www.sat.ltu.se
Stefan Buehler, Mathias Milz, www.sat.ltu.se 3
Our Research Program
Radiative Transfer
New Satellite Sensors
In Situ Measurements
Atmospheric Science
Motivation
Earth is getting warmer.
Climate predictions have large uncertainty.
(One) main reason: we do not know enough on clouds and humidity in the atmosphere.
Best studied by satellite sensors.
IPCC 4th assessment report, 2007
Figure 3.1. Annual anomalies of global land-surface air temperature (°C), 1850 to 2005, relative to the 1961 to 1990 mean for CRUTEM3 updated from Brohan et al. (2006). The smooth curves show decadal variations (see Appendix 3.A). The black curve from CRUTEM3 is compared with those from NCDC (Smithand Reynolds, 2005; blue), GISS (Hansen et al., 2001; red) and Lugina et al. (2005; green).
Why this Focus?
Humidity and clouds have strong influence on Earth radiation balance.
They create strong feedbacks, which can amplify or attenuate anthropogenic forcings, such as CO2 increase.
Currently one of the largest uncertainties in climate predictions.
Sun
Earth
Requires good data and modeling to achieve progress.
Stefan Buehler, Mathias Milz, www.sat.ltu.se 6
Radiative Transfer
http://www.sat.ltu.se/arts
ARTS - Atmospheric Radiative Transfer Simulator
• Public domain
• In collaboration with Chalmers
• Microwave to IR
• With scattering
Instrument simulation
Radiation flux simulation
Advanced Microwave Sounding Unit (AMSU)
On NOAA satellites. Similar instruments
on Metop and many other satellites.
Microwave temperature and humidity sensor.
The Metop satellite, image: ESA.
AMSU-B
Buehler, S. A. and V. O. John (2005), A Simple Method to Relate Microwave Radiances to Upper Tropospheric Humidity,J. Geophys. Res., 110, D02110, doi:10.1029/2004JD005111.
Water vapor
Oxygen Upper tropospheric humidity
Atmospheric Science
Buehler, S. A., M. Kuvatov, V. O. John, M. Milz, B. J. Soden and J. Notholt (2008), An Upper Tropospheric Humidity Data Set From Operational Satellite Microwave Data,J. Geophys. Res., 113, D14110, doi:10.1029/2007JD009314.
Upper tropospheric humidity (UTH) climatology from AMSU data
Data processed from 2000 SSM-T2 data since 1994 will be processed next
Humidity in the Climate System:Comparing infrared and microwave measurements
Infrared: • Operational measurements since 1979
• Different instruments with different properties
• Very sensitive to all clouds
Microwave: • Operational measurements since 1994
• Different instruments but all using the same spectral line
• Insensitive to thin clouds
Thorough characterisation of infrared and microwave datasets is necessary to use the data.
The Role of Cirrus Clouds: Shortwave
Cirrus clouds reflect sunlight and thus increase the planetary albedo.
Cooling effect
(AVHRR, Channel 1, 580-680nm, 25.1.2002, 13:30 UTC, Data Source: Met Office / Dundee Receiving Station)
The Role of Cirrus Clouds: Longwave Cirrus clouds are radiatively cold and
thus reduce the OLR. Heating effect
Attention: grayscale is normally reversed for IR images so that clouds look white.
Net cooling or heating effect of cirrus depends on physical properties• Thickness• Opacity• Particles• …
(AVHRR, Channel 4, 10.3-11.3μm, 25.1.2002, 13:30 UTC, Data source: Met Office / Dundee Receiving Station)
Stefan Buehler, Mathias Milz, www.sat.ltu.se 14
New Satellite SensorsBetter measurements of ice clouds
(Buehler et al., CIWSIR Mission Proposal, 2005, figure by Viju O. John)
Figure: Sula Systems
new ESA Mission Proposal “CloudIce”
Slow ascend of balloon-borne stereo imager through cloud
Understanding Ice Clouds in the Climate System:Ice Particle In-Situ Imaging
Climate Models SatelliteObservationsAnnual mean ice water path from different climate
models: Large discrepancies!
A priori assumptions on size, shape, volume of ice particles
Climate changeRole of ice particles in radiative budget andhydrological cycle
Instrument setup In-situMeasurementsCCD
First implementation of in-situ ice crystal stereo imaging:
Microscopeobjectives
(Flash lamp)Optical fiberFocusing lens
Captures of single-microscope imager
Ice Particle Measurements Size, Shape, Volume,
Concentration
Use measurements for Study cloud processes
(formation, growth,
precipitation, ...) Derive parameterizations of
shape/size distributions for
satellite retrievals and
climate models
(e.g., EarthCARE, SMILES, SPIDER, ...)
/aircraft/balloon/ground-based
- two microscope imaging probes triggered by detection system- allows reconstruction of 3D shape and improves size and volume estimate
Summary
Atmospheric humidity in its different phases (gas, liquid, solid) is a key parameter for understanding and predicting the climate system.
Approached by our group in different ways:- satellite humidity measurements- satellite cloud ice measurements- in situ cloud ice measurements- development of new satellite and in situ instruments- radiative transfer
Questions?