Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit espo.nasa.gov for information about our current projects.

 

Associated content: 

Hydration of the upper troposphere by tropical cyclones

Ray, E., and K. Rosenlof (2007), Hydration of the upper troposphere by tropical cyclones, J. Geophys. Res., 112, D12311, doi:10.1029/2006JD008009.

Microwave Temperature Profiler

The Microwave Temperature Profiler (MTP) is a passive microwave radiometer, which measures the natural thermal emission from oxygen molecules in the earth’s atmosphere for a selection of elevation angles between zenith and nadir. The current observing frequencies are 55.51, 56.65 and 58.80 GHz. The measured "brightness temperatures" versus elevation angle are converted to air temperature versus altitude using a quasi-Bayesian statistical retrieval procedure. The MTP has no ITAR restrictions, has export compliance classification number EAR99/NLR. An MTP generally consists of two assemblies: a sensor unit (SU), which receives and detects the signal, and a data unit (DU), which controls the SU and records the data. In addition, on some platforms there may be a third element, a real-time analysis computer (RAC), which analyzes the data to produce temperature profiles and other data products in real time. The SU is connected to the DU with power, control, and data cables. In addition the DU has interfaces to the aircraft navigation data bus and the RAC, if one is present. Navigation data is needed so that information such as altitude, pitch and roll are available. Aircraft altitude is needed to perform retrievals (which are altitude dependent), while pitch and roll are needed for controlling the position of a stepper motor which must drive a scanning mirror to predetermined elevation angles. Generally, the feed horn is nearly normal to the flight direction and the scanning mirror is oriented at 45-degrees with respect to receiving feed horn to allow viewing from near nadir to near zenith. At each viewing position a local oscillator (LO) is sequenced through two or more frequencies. Since a double sideband receiver is used, the LO is generally located near the "valley" between two spectral lines, so that the upper and lower sidebands are located near the spectral line peaks to ensure the maximum absorption. This is especially important at high altitudes where "transparency" corrections become important if the lines are too "thin." Because each frequency has a different effective viewing distance, the MTP is able to "see" to different distances by changing frequency. In addition, because the viewing direction is also varied and because the atmospheric opacity is temperature and pressure dependent, different effective viewing distances are also achieved through scanning in elevation . If the scanning is done so that the applicable altitudes (that is, the effective viewing distance times the sine of the elevation angle) at different frequencies and elevation angles are the same, then inter-frequency calibration can also be done, which improves the quality of the retrieved profiles. For a two-frequency radiometer with 10 elevation angles, each 15-second observing cycle produces a set of 20 brightness temperatures, which are converted by a linear retrieval algorithm to a profile of air temperature versus altitude, T(z). Finally, radiometric calibration is performed using the outside air temperature (OAT) and a heated reference target to determine the instrument gain. However, complete calibration of the system to include "window corrections" and other effects, requires tedious analysis and comparison with radiosondes near the aircraft flight path. This is probably the most important single factor contributing to reliable calibration. For stable MTPs, like that on the DC8, such calibrations appear to be reliable for many years. Such analysis is always performed before MTP data are placed on mission archive computers.

Instrument Type: 
Measurements: 
Aircraft: 
DC-8 - AFRC, ER-2 - AFRC, Global Hawk - AFRC, L-188C, M-55, Gulfstream V - NSF, WB-57 - JSC
Point(s) of Contact: 

Research Environment for Vehicle-Embedded Analysis on Linux

Instrument Type: 
Measurements: 
Point(s) of Contact: 

MODIS Airborne Simulator

The MODIS Airborne Simulator (MAS) is a multispectral scanner configured to approximate the Moderate-Resolution Imaging Spectrometer (MODIS), an instrument to be orbited on the NASA EOS-AM1 platform. MODIS is designed to measure terrestrial and atmospheric processes. The MAS was a joint project of Daedalus Enterprises, Berkeley Camera Engineering, and Ames Research Center. The MODIS Airborne Simulator records fifty spectral bands.

Instrument Type: 
Measurements: 
Aircraft: 
Point(s) of Contact: 

Lightning Instrument Project

The LIP (Lightning Instrument Package) measures lightning, electric fields, electric field changes, air conductivity. LIP provides real time electric field data for science and operations support.

The LIP is comprised of a set of optical and electrical sensors with a wide range of temporal, spatial, and spectral resolution to observe lightning and investigate electrical environments within and above thunderstorms. The instruments provide measurements of the air conductivity and vertical electric field above thunderstorms and provide estimates of the storm electric currents. In addition, LIP will detect total storm lightning and differentiate between intracloud and cloud-to-ground discharges. This data is used in studies of lightning/storm structure and lightning precipitation relationships.

Point(s) of Contact: 

High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer

The High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a microwave atmospheric sounder developed by JPL under the NASA Instrument Incubator Program. Operating with 25 spectral channels in 3 bands (50-60 Ghz, 118 Ghz, 183 Ghz), it provides measurements that can be used to infer the 3-D distribution of temperature, water vapor, and cloud liquid water in the atmosphere, even in the presence of clouds. The new UAV-HAMSR with 183GHz LNA receiver reduces noise to less than a 0.1K level improving observations of small-scale water vapor. HAMSR is mounted in payload zone 3 near the nose of the Global Hawk.

HAMSR was designed and built at the Jet Propulsion Laboratory under the NASA Instrument Incubator Program and uses advanced technology to achieve excellent performance in a small package. It was first deployed in the field in the 2001 Fourth Convection and Moisture Experiment (CAMEX-4) - a hurricane field campaign organized jointly by NASA and the Hurricane Research Division (HRD) of NOAA in Florida. HAMSR also participated in the Tropical Cloud Systems and Processes (TCSP) hurricane field campaign in Costa Rica in 2005. In both campaigns HAMSR flew as a payload on the NASA high-altitude ER-2 aircraft. It was also one of the payloads in the 2006 NASA African Monsoon Multidisciplinary Activities (NAMMA) field campaign in Cape Verde - this time using the NASA DC-8. HAMSR provides observations similar to those obtained with microwave sounders currently operating on NASA, NOAA and ESA spacecraft, and this offers an opportunity for valuable comparative analyses.

Instrument Type: 
Measurements: 
Point(s) of Contact: 

ER-2 Doppler Radar

EDOP is an X-band (9.6 GHz) Doppler radar nose-mounted in the ER-2. The instrument has two antennas: one nadir-pointing with pitch stabilization, and the other forward pointing. The general objectives of EDOP are the measurement of the vertical structure of precipitation and air motions in mesoscale precipitation systems and the development of spaceborne radar algorithms for precipitation estimation.

EDOP measures high-resolution time-height sections of reflectivity and vertical hydrometeor velocity (and vertical air motion when the hydrometeor fall speed and aircraft motions are removed). An additional capability on the forward beam permits measurement of the linear depolarization ratio (LDR) which provides useful information on orientation of the hydrometeors (i.e., the canting angle), hydrometeor phase, size, etc. The dual beam geometry has advantages over a single beam. For example, along-track horizontal air motions can be calculated by using the displacement of the ER-2 to provide dual Doppler velocities (i.e., forward and nadir beams) at a particular altitude.

EDOP is designed as a turn-key system with real-time processing on-board the aircraft. The RF system consists of a coherent frequency synthesizer which generates the transmitted and local oscillator frequencies used in the system, a pulse modulated (0.5 to 2.0 micro-second pulse) high gain 20 kW Traveling Wave Tube Amplifier which is coupled through the duplexer to the antenna, and the receiver which is comprised of a low-noise (~1dB) GaAs preamplifier followed by a mixer for each of the receive channels. The composite system generates a nadir oriented beam with a co-polarized receiver and a 350 forward directed beam with co- and cross- polarized receivers. The antenna design consists of two separate offset-fed parabolic antennas, with high polarization isolation feed horns, mounted in the nose radome of the ER-2. The antennas are 0.76 m diameter resulting in a 30 beamwidth and a spot size of about 1.2 km at the surface (assuming a 20 km aircraft altitude). The two beams operate simultaneously from a single transmitter.

Instrument Type: 
Aircraft: 
Point(s) of Contact: 

Pages

Subscribe to RSS - TCSP