the atmospheric radiation measurement (arm) program: an overview

ARMARMAtmospheric Radiation MeasurementAtmospheric Radiation Measurement

The Atmospheric Radiation Measurement (ARM) Program:

An Overview

The Atmospheric Radiation Measurement (ARM) Program:

An Overview

Robert G. EllingsonDepartment of Meteorology

Florida State UniversityTallahassee, FL

Robert G. EllingsonDepartment of Meteorology

Florida State UniversityTallahassee, FL


OutlineOutline

• Where did we start?

• What have we done?

• Where are we going?

• Where did we start?

• What have we done?

• Where are we going?


Where did we start?Where did we start?

1990: The single largest cause of variability in climate models is the treatment of clouds and their coupling to the earth radiation budget– Cess et al., JGR

– Our Changing Planet, USGCRP

=> the cloud parameterization problem

1990: The single largest cause of variability in climate models is the treatment of clouds and their coupling to the earth radiation budget– Cess et al., JGR

– Our Changing Planet, USGCRP

=> the cloud parameterization problem


ARM GoalARM Goal

To improve the performance of General Circulation Models (GCMs) by:

• Improving the treatment of radiative transfer under clear sky, general

overcast, and broken cloud conditions

• Improving the parameterization of properties and formation of clouds

To improve the performance of General Circulation Models (GCMs) by:

• Improving the treatment of radiative transfer under clear sky, general

overcast, and broken cloud conditions

• Improving the parameterization of properties and formation of clouds


ARM Questions

• If we can specify a cloud field, can we compute the radiative fluxes?

=> Requires knowledge of cloud properties

(3D structure, water path, phase, size,

etc.)


Need atmospheric observations to

-- test hypothesis in process model studies

-- analyze for empirical relationships and statistical characteristics


ARM Questions

• If we can specify a cloud field, can we compute the radiative fluxes?

=> Requires knowledge of cloud properties

(3D structure, water path, phase, size, etc.)

• If we can specify the large-scale atmospheric fields, can we predict the cloud field properties?

=> Requires 3D field of state properties and cloud

field properties


Need data sets that describe the large scale environment in which clouds form


ARM Program ComponentsARM Program Components

• Development of ground-based remote sensing facilities

• Continuous data acquisition and archival• Data analysis• Physical modeling• Parameterization development and testing

• Development of ground-based remote sensing facilities

• Continuous data acquisition and archival• Data analysis• Physical modeling• Parameterization development and testing


What have we done?What have we done?

• Sites

• Science

• Sites

• Science


Location of Current ARM Sites


Southern Great Plains Site

Central Facility


Southern Great Plains Central FacilitySouthern Great Plains Central Facility


North Slope of Alaska SiteNorth Slope of Alaska Site


Tropical Western Pacific SiteTropical Western Pacific Site


Tropical Western Pacific SiteTropical Western Pacific Site

Manus Island

Nauru


Instrumentation at SitesInstrumentation at Sites

• 35 GHz Radar (cloud properties)

• Lidar (pulsed laser; particle and thin cloud properties )

• Sky imagers (cloud cover)

• Broad-band and narrow-band radiometers (solar and infrared radiation)

• Microwave radiometer (water vapor and liquid water)

• Meteorology sensors (temp, humidity, winds)

• 35 GHz Radar (cloud properties)

• Lidar (pulsed laser; particle and thin cloud properties )

• Sky imagers (cloud cover)

• Broad-band and narrow-band radiometers (solar and infrared radiation)

• Microwave radiometer (water vapor and liquid water)

• Meteorology sensors (temp, humidity, winds)


ARM Science -- Some Examples*ARM Science -- Some Examples*

• Instrument development and data analysis

• Radiation Studies• Model testing and development

* Lots of possible choices!



* Lots of possible choices!


Total Sky Imager -- NauruTotal Sky Imager -- Nauru

99-07-13 1150 99-07-13 1351


ARM Raman LidarARM Raman Lidar


ARM Millimeter Cloud Radar (MMCR)ARM Millimeter Cloud Radar (MMCR)


35 GHz Radar Reflectivity (Arctic)35 GHz Radar Reflectivity (Arctic)


Radar dataRadar data

ARM now has 4 radars in operation:• SGP – 4 years of data• TWP Nauru – 2.5 years• TWP Manus – 1+ years• NSA – 2 years

ARM now has 4 radars in operation:• SGP – 4 years of data• TWP Nauru – 2.5 years• TWP Manus – 1+ years• NSA – 2 years


ARM Science -- Some Examples*ARM Science -- Some Examples*






The Radiation QuestionsThe Radiation Questions

Can we compute solar transmission and infrared emission accurately– in a clear atmosphere?

– in an atmosphere with an overcast, single-layer cloud?

– in an atmosphere with broken clouds and/or multiple cloud layers?

Can we compute solar transmission and infrared emission accurately– in a clear atmosphere?

– in an atmosphere with an overcast, single-layer cloud?

– in an atmosphere with broken clouds and/or multiple cloud layers?


Clear AtmosphereClear Atmosphere

• Yes– Infrared irradiance to < 5 W/m2 (2%)

– Solar direct irradiance to < 0.5%

– Solar diffuse irradiance to < 10 W/m2

(if we account for diffuse radiometer offset)

• Remaining uncertainty probably due to absorption by trace gas species or aerosol

• Yes– Infrared irradiance to < 5 W/m2 (2%)

– Solar direct irradiance to < 0.5%

– Solar diffuse irradiance to < 10 W/m2

(if we account for diffuse radiometer offset)

• Remaining uncertainty probably due to absorption by trace gas species or aerosol


Single Layer CloudSingle Layer Cloud

• Maybe (anomalous absorption problem)– Question is whether measured atmospheric

absorption in clouds exceeds calculated absorption

– Published articles show both

Measured = 1.5 * Calculated

Measured ~ Calculated

• Maybe (anomalous absorption problem)– Question is whether measured atmospheric

absorption in clouds exceeds calculated absorption

– Published articles show both

Measured = 1.5 * Calculated

Measured ~ Calculated


Current ARM Role in the ProblemCurrent ARM Role in the Problem

• ARESE II Experiment (March, 2000)– Stratus cloud experiment at SGP site

– Instrument radiation airplane flying above cloud over central facility

– Remote sensing of cloud from ground

– Some in cloud sampling with second aircraft

• Data released to public after examination and evaluation by ARESE science team

• ARESE II Experiment (March, 2000)– Stratus cloud experiment at SGP site

– Instrument radiation airplane flying above cloud over central facility

– Remote sensing of cloud from ground

– Some in cloud sampling with second aircraft

• Data released to public after examination and evaluation by ARESE science team


Results To DateResults To Date

• Analyzed 3 cloud days• Preliminary results show

measured = 1.1 – 1.15 * calculated• Experimental uncertainty

– In individual measurements: few %

– In net flux (difference): few % to 10 %

• Evaluation continues, group of papers to be submitted by end of summer

• Analyzed 3 cloud days• Preliminary results show

measured = 1.1 – 1.15 * calculated• Experimental uncertainty

– In individual measurements: few %

– In net flux (difference): few % to 10 %

• Evaluation continues, group of papers to be submitted by end of summer


Broken Clouds Broken Clouds

• Don’t know• Work in progress

– Defining 3D cloud properties

– Developed 3D radiation codes for solar spectrum

– Comparison study of 3D codes

• Don’t know• Work in progress

– Defining 3D cloud properties

– Developed 3D radiation codes for solar spectrum

– Comparison study of 3D codes


ARM Education Outreach ProgramARM Education Outreach Program

• ARM Program mandates an education outreach program for each CART site.

• Education outreach must be relevant to the needs of the local and regional communities.

• Content and management of the program has been determined by the CART Site Manager.

• Starting in FY2000, the Education Outreach Program is now integrated across all 3 sites.

• ARM Program mandates an education outreach program for each CART site.

• Education outreach must be relevant to the needs of the local and regional communities.

• Content and management of the program has been determined by the CART Site Manager.

• Starting in FY2000, the Education Outreach Program is now integrated across all 3 sites.


Check out our Scavenger Hunt !!

http://www.arm.gov/docs/education/


NSA Classroom visits NSA Classroom visits

Classroom visits in Barrow

Classroom visits in Atqasuk


Curriculum Workshops in the TropicsCurriculum Workshops in the Tropics

ARM scientists and regional collaborators present background materials. Teachers practice activities that demonstrate concepts for later use in their classrooms.


TWP Teacher ParticipationTWP Teacher Participation

Manus: “Atmospheric Pressure”

(Module 1, Book 1)

Manus: “Making Clouds”

(Module 2, Book 1)


TWP Teacher ParticipationTWP Teacher Participation

Manus: “When Land Ice Melts”

(Module 4, Book 1)

Port Moresby: “Plant Growth and Carbon Dioxide”

(Module 3, Book 2)


The educational outreach portion of the ARM Program seeks to provide schools with the materials necessary to use environmental data in the classroom.

ARM data is available online through these web pages.

http://outreach.ocs.ou.edu/arm


www.arm.gov

ARM Web Site


Is ARM Still Needed?Is ARM Still Needed?

• IPCC Report (2001) cites largest areas of uncertainty in climate change scenarios:– Cloud feedbacks

– Effect of changing particle loading on cloud properties

• Too much of what we have learned is not yet incorporated into climate models

• Climate models need to be evaluated quantitatively and ARM data are part of the necessary tools

• IPCC Report (2001) cites largest areas of uncertainty in climate change scenarios:– Cloud feedbacks

– Effect of changing particle loading on cloud properties

• Too much of what we have learned is not yet incorporated into climate models

• Climate models need to be evaluated quantitatively and ARM data are part of the necessary tools


ARM FutureARM Future

• Continue to operate ground-based sites– 10 year time series

– Transition some sites to permanent facility

– Construct mobile facility

• Expand science activities in parameter-ization and model development– ARM Fellows at NCEP and ECMWF

– Promote model comparison studies

– Link to operational testing of climate models

• Continue to operate ground-based sites– 10 year time series

– Transition some sites to permanent facility

– Construct mobile facility

• Expand science activities in parameter-ization and model development– ARM Fellows at NCEP and ECMWF

– Promote model comparison studies

– Link to operational testing of climate models


ARM Future (2)ARM Future (2)

• Forge stronger links with national programs in hydrology, human health, and satellite remote sensing

– NASA Earth Observing System (EOS)

– DOE Tropospheric Aerosol Program (TAP)

• Forge links with international programs

– World Climate Research Programme (GEWEX)

– NASA Cloud Radar (Canada) and Lidar (France)

– European Space Agency

• Forge stronger links with national programs in hydrology, human health, and satellite remote sensing

– NASA Earth Observing System (EOS)

– DOE Tropospheric Aerosol Program (TAP)

• Forge links with international programs

– World Climate Research Programme (GEWEX)

– NASA Cloud Radar (Canada) and Lidar (France)

– European Space Agency


In Conclusion, ARM …In Conclusion, ARM …

• Has a well defined mission in the climate research community

• Is a highly successful program in terms of its science impact

• Has important questions to address over the next 10 years

• Has a well defined mission in the climate research community

• Is a highly successful program in terms of its science impact

• Has important questions to address over the next 10 years


For More Information Please Contact

For More Information Please Contact

Tom Ackerman

Chief Scientist

Pacific Northwest National Laboratory

Tom Ackerman

Chief Scientist

Pacific Northwest National Laboratory

the atmospheric radiation measurement (arm) program: an overview

Documents

knowledge of cloud properties

singlelayer cloud

parameterization of

d field of state properties

clear sky

instrument development

solar diffuse irradiance

solar direct irradiance