Overview of the Atmospheric
Radiation Measurement (ARM)
Program’s Mobile Facility (AMF)
Dave Turner
University of Wisconsin – Madison
COPS Workshop
10-11 April 2006
Hohenheim, Germany
The Real People
Behind the AMF

Head Scientist: Mark Miller
 Team Members: Mary Jane Bartholomew,
Larry Jones, Kim Nitschke, Doug Sisterson
 Chief Engineer: Kevin Widener
 Program Manager: Wanda Ferrell
The ARM Mobile Facility
Initially Deployed in 2005
Pt. Reyes, California
Niamey, Niger, Africa
Charter

Detailed measurements of the cloudy
atmospheric column
– in regions of the climate system that are generally
undersampled
– in association with the international atmospheric
science community

Subset of instruments located at ARM’s fixed
sites
– Active and passive sensors
– Enhanced surface aerosol system

Deployment duration is 6-12 months
Site Selection Process

International Proposal Competition
– ARM Climate Research User Facility
(ACRF) Board selects winning proposal



Composed of 40% ARM Scientists and 60%
external scientists
Final decision is made by the ARM Program
Manager
Proposals rated on scientific merit, facility
leverage, and logistical feasibility
Active and Passive Cloud
Remote Sensors

3.2-mm Doppler Cloud Radar (WACR)
– 30-m vertical resolution
– 2-sec temporal resolution
– 256 pt. Doppler spectrum at each range gate,
–
–
–
–
continuously recorded
Polarization
Minimum detectable signal ~ -40 dBZ at 5-km
Sensitivity may exceed –60 dBZ in lowest 1-km
Internal calibration verified by corner reflector
3.2 mm Cloud Radar Doppler
Velocity from Niamey, Niger
“First light”
Active and Passive Cloud
Remote Sensors (cont.)

Vaisala Laser Ceilometer
–
–
–
–

905-nm
15-m, 15-sec resolution
Backscatter profile, cloud base height
Maximum height in cloud free atmosphere: 5.5-km
Micropulse Lidar (MPL)
–
–
–
–
–
523-nm
30-m, 30-sec resolution
Backscatter Profile, Cloud base height
Maximum height in cloud free atmosphere: 18-km
Cloud optical thickness, aerosol extinction
MPL Example From Niamey
Backscatter (arb units)
Height (km)
20
15
10
LIQUID CLOUDS
5
Biomass Burning
Dust
0
0000
1200
Time (UTC)
2400
Active and Passive Cloud
Remote Sensors (cont.)

2-Channel Microwave Radiometer (MWR)
– 23.8 and 31.4 GHz
– Precipitable water vapor and integrated liquid
water path

12-Channel Microwave Radiometer Profiler
– Vertical profiles of water vapor, temperature, and
liquid water content (coarse)
– 5 min temporal resolution
– 5 frequencies near water vapor resonance
between 22.235 and 30 GHz
– 7 frequencies in the band of oxygen resonances
between 51 and 59 GHz
ARM’s MWRs
Clear Sky Microwave Optical Depth Spectrum
Active and Passive Cloud
Remote Sensors (cont.)

Wind Profiler
–
–
–
–

75-m, 6-min resolution
915 MHz [1270-1400 MHz COPS]
Minimum Height: 120-m
Maximum height: 5.5-km
Atmospheric Emitted Radiance Interferometer
(AERI)
– 3-19.2 mm (1 cm-1 resolution)
– 6-min resolution (20-30 sec possible for COPS)
– 1.3 degree field-of-view
Clear Sky AERI Spectra
Surface Shortwave Radiation

Downwelling and Upwelling Total
– 0.3-3.0 mm global hemispheric irradiance
– Unshaded pyranometer

Downwelling Diffuse
– 0.3-3.0 mm global hemispheric irradiance
– shaded pyranometer

Direct-Normal
– 0.3-3.0 mm
– Tracking pyroheliometer with 5.7 degree field-of-
view
Surface Shortwave Radiation

Multi-filter rotating shadowband radiometer
(MFRSR)
– Total, Diffuse, and Direct-Normal
– 6 channels @ 10-nm width
Wavelength (nm)
Application
415
aerosol
500
aerosol, ozone
615
aerosol, ozone
673
aerosol, ozone
870
aerosol
940
water vapor
Surface Longwave Radiation

Downwelling and upwelling Total
– 4.0-50 mm global hemispheric irradiance
– shaded pyrgeometer
Surface Broadband Summary
Measurement
Radiometer
Model
Uncertainty
Direct Normal Beam
NIP
±3.0%
or 4.0 Wm-2
Diffuse Horizontal
(sky)
PSP
±6.0%
or 20.0 Wm-2
Downwelling
Shortwave (global)
PSP
±6.0%
or 10.0 Wm-2
Downwelling
Longwave
(atmospheric)
PIR
±2.5%
or 4.0 Wm-2
Upwelling Shortwave
(Reflected)
PSP
±6.0%
or 15.0 Wm-2
Upwelling Longwave
(terrestrial)
PIR
±2.5%
or 4.0 Wm-2
Total Sky Imager (TSI)
TSI
Boundary Layer Cloud
Cirrus
Interesting Sky Images
RV Ron Brown
Central Pacific
AOT=0.08
RV Ron Brown
AMF
Sea of Japan Niamey, Niger
AOT=0.98
AOT=2.5-3.0
Surface Aerosol System

Two 3-Wavelength Nephelometers
– 450, 550, 700 nm
– One humidified and one dry
– Total angular scattering and hemispheric backscattering
coefficients (90º-170º)
– Scattering coefficients as a function of RH

Particle Soot Absorption Photometer (PSAP)
– Absorption coefficient at 550 nm
– Extinction coefficient when combined with nephelometer
measurements

Cloud Condensation Nuclei Counter (CCN)
– 7 supersaturation set points ranging from 0.18-1.37
– 30-minutes to span range
– Measures CN and CCN
CVI
inlet
aerosol
trailer
PNNL
SMPS
PNNL
AMS
PNNL
CCN
AMF AOS
Instruments
denoted AOS
CVI
pumps
UFCN
AOS
PSAP
AOS CPC
CCN
AOSNephs
humidifier
AOS
pumps
UCDavis
Sizers
NASA Cadenza
Lidar
BNL SMPS
AOS
inlet
How it really
looked
during
MASRAD
AOS
TRAC
CVI
Neph CVI
TRAC
CVI
PSAP
hygro
CPC
http://www.cmdl.noaa.gov/gallery/AMF
UPS
Surface Meteorology

Standard variables
– T, RH, P, winds (10-m for COPS)
– Rainfall (optical rain gauge)
– Present Weather
 Optical measurement of visibility
 Fog detection

Latent, sensible, and carbon fluxes
– Eddy correlation (2-m height)
New Additions to AMF

CIMEL Sun Photometer
– Before COPS

Possibly ARM’s new 90 / 150 GHz
microwave radiometer
Data, Data, Data

AMF data are generally available within a day or two
from the ARM data archive (www.archive.arm.gov)
– True for all ARM data
– Data quality documented afterwards
– Reprocessing is occasionally required

Data are open to all investigators
 Some data streams can be accessed in real-time, if
needed (i.e., radiosonde profiles)
 Recommendation: talk with Mark Miller and/or the
“instrument mentors” when you start using various
ARM datastreams…
 ARM tracks data users (# of requests, # of different
datastreams, etc.) – this is an important metric
Summary

AMF has most of the instrumentation used
at the various ARM fixed sites
 Supplements the instrumentation provided
by our European colleagues
 Excited about COPS, and looking forward
to a fruitful experiment!