The Wisconsin Snow and Cloud Terra 2000 (WISC-T2000) Experiment was a NASA campaign that aimed to validate satellite products from the MODIS instrument onboard Terra. WISC-T2000 consisted of one deployment based out of Madison, Wisconsin, from February to March 2000. NASA ER-2 was equipped with remote sensors such as the MODIS Airborne Simulator (MAS), Air Multi-angle Imaging Spectrometer (AirMISR), and Cloud Lidar System (CLS) to collect cloud and snow properties and atmospheric measurements in the Upper Midwest for Terra validation. ER-2 also conducted flights over the Department of Energy (DoE) Atmospheric Radiation Measurements (ARM) User Facility site in Oklahoma, where ground truth observations were collected. WISC-T2000 was one of the first validation campaigns for the Terra satellite.
The Cloud Lidar System (CLS) was an airborne lidar system that operated on the ER-2 aircraft. It measured lidar backscatter to determine the height structure of clouds, cloud thickness, and other cloud properties. CLS was also used to determine aerosol properties. It used a Nd-YAG operating at 1064 and 532 nm and had a pulse repetition frequency of 10 Hz. CLS had a horizontal resolution of 20 m and a vertical sampling resolution of 7.5 m.
The Airborne Multi-angle Imaging SpectroRadiometer (AirMISR) is a remote-passive, pushbroom sensor that was developed by the Jet Propulsion Laboratory (JPL). AirMISR provides visible and infrared imagery similar to that of the MISR instrument on the Terra satellite. It collects data with a single camera at nine viewing angles and operates across four spectral bands: 443 nm, 555 nm, 670 nm, and 865 nm. AirMISR has a swath width of around 11 km and an instantaneous field of view of 7 m x 6 m at nadir. AirMISR is typically flown on the NASA ER-2 aircraft due to its high flight altitude of 20 km.
The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer designed to simulate the satellite instrument Moderate-Resolution Imaging Spectrometer (MODIS). MAS operates across 50 spectral channels in the 0.55 to 14.2 μm range to provide high-resolution imagery of clouds and surface features. MAS has a horizontal spatial resolution of 50 m and a swath width of about 36 km at an altitude of 20 km at nadir. It has a scan rate of 6.25 Hz with each scan line containing 716 pixels.
The Scanning High-resolution Interferometer Sounder (S-HIS) is an airborne cross-track scanning interferometer developed by the Space Science and Engineering Center at the University of Wisconsin-Madison. It measures the emitted thermal radiation between 3.3 and 18 microns at high spectral resolution. These measurements can be used to derive atmospheric profiles of temperature and water vapor in clear-sky conditions. S-HIS has a spatial resolution of 2 km and a swath width of 40 km at an altitude of 20 km at nadir. It has a sampling frequency of 0.5 s and an absolute radiance accuracy of 0.2 K.
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Profiles
Earth Science > Atmosphere > Atmospheric Temperature
Radiosondes are a balloon-borne instrument package used to collect profile measurements of pressure, temperature, humidity, and winds. These sensors are connected to a radio transmitter that sends the measurements to a ground receiver typically operating in the 400-406 MHz range. They typically provide measurements at 1-6 seconds, depending on the type and manufacturer of the radiosonde. Radiosondes are used for weather forecasting, ground truth satellite data, atmospheric research, and input for weather prediction models.
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Profiles
Ceilometers are ground-based, remote-sensing sensors that provide measurements of cloud ceilings and vertical visibility. They use either a laser beam or another light source to detect backscatter of clouds, precipitation, and aerosols. Ceilometers can provide detailed and accurate measurements in all types of weather conditions and have low operating costs. Ceilometers are typically used in boundary layer and cloud research applications.
Generic-Atmospheric State (Gen-AtmsState) refers to non-specific instruments on a platform used for measurements of atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed/direction. Types of atmospheric state instruments include thermometers, hygrometers, barometers, and anemometers.
Earth Science > Atmosphere > Atmospheric Water Vapor
Earth Science > Atmosphere > Atmospheric Pressure
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Humidity
Earth Science > Atmosphere > Atmospheric Temperature > Surface Temperature > Air Temperature
The Ultra-High Frequency (UHF) Wind Profiler is a ground-based Doppler radar. It measures electromagnetic signals to detect wind speed and direction. UHF Wind Profilers operate at the 300-1000 MHz frequency range. Due to operating at a high frequency, they allow for high-resolution wind measurements within the boundary layer.
The Millimeter-Wavelength Cloud Radar (MMCR) is a ground-based radar developed by the NOAA Environmental Technology Laboratory (ETL) for the Department of Energy (DoE) Atmospheric Radiation Measurement (ARM) sites. MMCR provides long-term observations of radar reflectivity, Doppler velocity, spectrum width, and other radar parameters for precipitating and nonprecipitating clouds up to 20 km above ground level (AGL). It is a vertically pointing, single-polarization radar system that operates at around 35 GHz. MMCR has a beamwidth of 0.2 degrees and typical vertical resolutions of 45 and 90 meters.
The microwave radiometers (MWRs) are ground-based radiometers manufactured by Radiometrics Corporation and operated by the Atmospheric Radiation Measurement (ARM) Research Facility. MWR measures brightness temperature at 23.8 and 31.4 GHz to derive column-integrated amounts of water vapor and liquid water in the atmosphere. MWR has a field of view (FOV) from about 5.9 to 4.5 degrees depending on the channel and has a typical time resolution of 20 s for sky-view observations.
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Water Vapor
Earth Science > Spectral/engineering > Microwave > Brightness Temperature
Earth Science > Atmosphere > Atmospheric Water Vapor
The Atmospheric Emitted Radiance Interferometer (AERI) is a ground-based passive interferometer developed by the University of Wisconsin Space Science and Engineering Center (UW-SSEC) for the Department of Energy (DoE) Atmospheric Radiation Measurement (ARM) Program. It uses Fourier transform spectroscopy to measure downwelling thermal infrared emissions from the atmosphere. These measurements can be used to provide profile measurements of atmospheric temperature and water vapor and detect trace gases. AERI operates across the 3.3-19 μm spectral range and up to 25 μm for the extended range version of the instrument. It has an optimal vertical resolution of 100 meters and completes a full sky scan about every 20 seconds.
Generic-Radiometers refer to non-specific radiometers on a platform. These are typically passive microwave radiometers that measure brightness temperature. Radiometers can be used to retrieve temperature and water vapor profiles, soil moisture content, ocean salinity, precipitation and cloud properties, and vegetation.
Earth Science > Spectral/engineering > Microwave > Brightness Temperature
The Micropulse Lidar (MPL) is a ground-based lidar system used for cloud detection. It measures lidar backscatter at 532 nm to retrieve cloud properties such as cloud top and base height. It can also be used for the detection of aerosols. MPL has a vertical resolution of 15 m and a maximum range of 18 km. MPL can operate autonomously and typically provides 10-second averaged data.
Earth Science > Spectral/engineering > Lidar > Lidar Depolarization Ratio
Sunphotometers are passive optical sensors that measure the amount of sunlight. They are pointed directly at the sun to measure direct sunlight and not sunlight scatter from aerosols. These measurements can be used to determine the aerosol optical depth by following Beer’s Law. Sunphotometers have been deployed on aircraft, research vessels, and field sites for aerosol research and monitoring.
The Multifilter Rotating Shadowband Radiometer (MFRSR) is a ground-based passive radiometer used to measure the global and diffuse components of solar irradiance. It measures solar irradiance across six narrowband channels and one broadband channel. The nominal wavelengths of the narrowband channels are 415, 500, 615, 673, 870, and 940 nm. MFRSR has a typical sampling interval of 20 seconds and takes measurements at four different shadowband positions: nadir, first side-band, sun-blocked, and second side-band. MFRSR is deployed across several of the Department of Energy’s Atmospheric Radiation Measurement (ARM) User Facility sites.
