The Arctic Winter Millimeter-Wave Radiometric Experiment 2004
Long-term, high resolution measurements of atmospheric properties in
the Arctic
are critical to efforts to observe and predict changes in the global
climate.
Measurement of water vapor during the cold arctic winter is very
difficult because of the lack of sensitivity of conventional water
vapor radiometers to low amounts of water vapor and because of
the uncertainties of radiosondes during these conditions as well.
There is a concern that instruments currently used for climate
observations may be inadequate to measure low amounts of
total-column precipitable water vapor (PWV) in the Arctic.
An Intensive Operating Period (IOP) was conducted at U. S. Department of
Energy's Atmospheric Radiation Measurement (ARM) Program's field site near
Barrow, Alaska, during March 9 to April 9 2004. Instruments deployed
include the Ground-based Scanning Radiometer of NOAA's Environmental
Technology Laboratory (with frequencies ranging from 50 to 380 GHz),
the Microwave Radiometer and the Radiometric Profiler of the Atmospheric
Radiation Measurement (ARM) Program (frequencies from 22.235 to 60 GHz),
and the Infrared Cloud Imager operated by Montana State University.
These instruments were supplemented by 4-times-a-day Vaisala RS90
radiosonde observations and other in situ observations, including several
"Snow White" Chilled Mirror radiosondes. In addition, all of the ARM active
cloud sensors (radar and lidar) were operating.
The major goals were to demonstrate that millimeter wavelength
radiometers can substantially improve water vapor observations during
the Arctic winter. Secondary goals included forward model studies over a
broad frequency range, demonstration of recently developed calibration
techniques, the comparison of several types of in situ water vapor
sensors, and the application of infrared imaging techniques.
Goals
- Compare microwave vs. millimeterwave
radiometric response to low amounts of water vapor
and arctic clouds
- Obtain data for forward model radiative transfer studies at frequencies ranging from 18 to 340 GHz
- Demonstrate new radiometric receiver and calibration technology
- Inter-comparison with ARM instruments: Water Vapor Radiometer (MWR),
Microwave Profiler (MWRP), Atmospheric Emitted Radiance Interferometer
(AERI), Micropulse Lidar (MPL), Millimeter-Wavelength Cloud Radar (MMCR)
Instruments Deployed
Platform |
Frequencies (GHz) |
Parameters Derived |
ARM Radiometrics WVR (MWR) |
23.8, 31.4 |
Precipitable Water Vapor (PWV), Integrated Cloud Liquid (ICL) |
Ground-based Scanning Radiometer (GSR) |
50-56 (11 channels) |
Temperature (T) profile, ICL |
89H, 89V |
ICL |
183.31 ± ( 0.5, ± 1, ± 3, ± 5, ± 7,
± 12, ± 15) |
PWV |
340H, 340V |
PWV, ICL |
380.2 + (±4, ±9, ±17) |
PWV |
10 microns |
Cloud presence |
ARM Microwave Profiler (MWRP) {Radiomerics Site} |
22.235, 23.035 ,23.835, 26.235, 30.000, 51.250, 52.280, 53.850, 54.940, 56.660, 57.290, 58.800 |
T profile, PWV, ICL |
Infrared Cloud Imager (ICI) |
8-14 microns |
Spatial cloud coverage |
Global Positioning System (GPS) |
|
PWV |
Radiosonde |
Number of Launches |
Parameters Derived |
Vaisala RS90 sondes |
4-times a day at ARM duplex |
T, Pressure (P) and Humidity (RH) profiles |
1-time a day at Great White site |
T, P and RH profiles |
Snow White (with chilled mirror) sondes |
10 total |
T, P and RH profiles |
National Weather Service sondes |
2-times a day |
T, P and RH profiles |
|