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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Monsoon Convection during the South China Sea Monsoon Experiment Observed from Shipboard Radar and the TRMM Satellite

A main goal of the recent South China Sea Monsoon Experiment (SCSMEX) was to study convective processes associated with the onset of the Southeast Asian summer monsoon. The NASA TOGA C-band scanning radar was deployed on the Chinese research vessel Shi Yan #3 for two 20 day cruises, collecting dual-Doppler measurements in conjunction with the BMRC C-Pol dual-polarimetric radar on Dongsha Island. Soundings and surface meteorological data were also collected with an NCAR Integrated Sounding System (ISS). This experiment was the first major tropical field campaign following the launch of the Tropical Rainfall Measuring Mission (TRMM) satellite. These observations of tropical oceanic convection provided an opportunity to make comparisons between surface radar measurements and the Precipitation Radar (PR) aboard the TRMM satellite in an oceanic environment. Nearly continuous radar operations were conducted during two Intensive Observing Periods (IOPS) straddling the onset of the monsoon (5-25 May 1998 and 5-25 June 1998). Mesoscale lines of convection with widespread regions of both trailing and forward stratiform precipitation were observed during the active monsoon periods in a southwesterly flow regime. Several examples of mesoscale convection will be shown from ship-based and spacebome radar reflectivity data during times of TRMM satellite overpasses. Further examples of pre-monsoon convection, characterized by isolated cumulonimbus and shallow, precipitating congestus clouds, will be discussed. A strong waterspout was observed very near the ship from an isolated cell in the pre-monsoon period, and was well documented with photography, radar, sounding, and sounding data.

Rickenbach, Tom↗
NASA NTRS1999

The Tropical Rainfall Measuring Mission and Vern Suomi 's Vital Role

The Tropical Rainfall Measuring Mission was a new concept of measuring rainfall over the global tropics using a combination of instruments, including the first weather radar to be flown in space. An important objective of the mission was to obtain profiles of latent heat in order to initialize large-scale circulation models and to understand the relationship between short-term climate changes in relation to rainfall variability. The idea originated in the early 1980's from scientists at the Goddard Space Flight Center/NASA who had been involved with attempts to measure rain with a passive microwave instrument on Nimbus 5 and had compared its results with rain falling in the area covered by the GATE1 radar ships. Using an imaginary satellite flying over the GATE ships, scientists showed that a satellite with an inclined orbit of 30-35 degrees could obtain monthly rainfalls with a sampling error of less than 10 percent over 5 degree by 5 degree areas. The Japanese proposed that they could build a nadir-scanning rain radar for the satellite. Vern Suomi was excited by this mission from the outset, since he recognized the great importance of adequate rainfall measurements over the tropical oceans. He was a charter member of the Science Steering Team and prepared a large part of the Report. While the mission attracted strong support in the science community, it was opposed by some of the high-level NASA management who feared its competition for funds with some much larger Earth Science satellites. Vern was able to overcome this opposition and to generate Congressional support, so that the Project finally got underway on both sides of the Pacific in 1991. The paper will discuss the design of the satellite, its data system and ground validation program. TP.NM was successfully launched in late 1997. Early results will be described. 1 GATE stands for GARP Atlantic Tropical Experiment and GARP stands for Global Atmospheric Research Program.

Simpson, Joanne↗
NASA NTRS1999

Processes Affecting Tropospheric Ozone Inferred from Ozonesonde and Other Tracer Data from the R/V R H Brown Atlantic Cruise (37N-34S) in January-February 1999

During the Aerosols-99 trans-Atlantic cruise from Norfolk, VA, to Cape Town, South Africa, 22 ozonesondes were launched from the NOAA R/V R H Brown between 17 Jan and 6 Feb 1999, with all sondes but one reaching 30 km. A composite of ozone profiles along the transect shows high free tropospheric ozone (up to 100 ppbv at 9 km) between 5N and 20S, a coherent feature straddling either side of the ITCZ. Latitudinal variations of tropospheric ozone are interpreted using correlative measurements of surface ozone, CO, water vapor, and aerosol optical thickness (column absorbance) measured from the ship. Elevated ozone in the lower troposphere results from photochemical reactions of precursors emitted by biomass burning north of the ITCZ. However, the greatest ozone mixing ratios are in the mid-troposphere south of the ITCZ, which gives evidence of interhemispheric transport. Column-integrated tropospheric ozone, 35 DU from 0-16 km, agrees with that derived from the TOMS satellite by the modified-residual method [Thompson and Hudson, 1999]. NCEP wind fields, ship-launched radiosondes and back trajectories are consistent with a picture of recirculating air parcels centered in the tropical Atlantic region which is identified with the maximum wave-one amplitude in total ozone seen in sondes and by satellite.

Thompson, Anne M.↗
NASA NTRS1997

The Atlantic Meridional Transect: Spatially Extensive Calibration and Validation of Optical Properties and Remotely Sensed Measurements of Ocean Colour

Twice a year, the Royal Research Ship (RRS) James Clark Ross (JCR) steams a meridional transect of the atlantic Ocean between Grimsly (UK) and Stanley (Falkland Islands) with a port call in Montevideo (Uruguay), as part of the annual research activities of the British Antarctic Survey (BAS). In September, the JCR sails from the UK, and the following April it makes the return trip. The ship is operated by the BAS for the Natural Environment Research Council (NERC). The Atlantic Meridional Transect (AMT) Program exploits the passage of the JCR from approximately 50 deg. N to 50 deg. S with a primary objective to investigate physical and biological processes, as well as to measure the mesi-to-basin-scale bio-optical properties of the atlantic Ocean. The calibration and validation of remotely sensed observations of ocean colour is an inherent objective of these studies: first, by relating in situ measurements of water leaving radiance to satellite measurement, and second, by measuring the bio-optically active constituents of the water.

Aiken, James↗
NASA NTRS1999

Arctic Summer Ice Processes

The primary objective of this study is to estimate the flux of heat and freshwater resulting from sea ice melt in the polar seas. The approach taken is to examine the decay of sea ice in the summer months primarily through the use of spaceborne Synthetic Aperture Radar (SAR) imagery. The improved understanding of the dynamics of the melt process can be usefully combined with ice thermodynamic and upper ocean models to form more complete models of ice melt. Models indicate that more heat is absorbed in the upper ocean when the ice cover is composed of smaller rather than larger floes and when there is more open water. Over the course of the summer, floes disintegrate by physical forcing and heating, melting into smaller and smaller sizes. By measuring the change in distribution of floes together with open water over a summer period, we can make estimates of the amount of heating by region and time. In a climatic sense, these studies are intended to improve the understanding of the Arctic heat budget which can then be eventually incorporated into improved global climate models. This work has two focus areas. The first is examining the detailed effect of storms on floe size and open water. A strong Arctic low pressure storm has been shown to loosen up the pack ice, increase the open water concentration well into the pack ice, and change the distribution of floes toward fewer and smaller floes. This suggests episodic melting and the increased importance of horizontal (lateral) melt during storms. The second focus area is related to an extensive ship-based experiment that recently took place in the Arctic called Surface Heat Budget of the Arctic (SHEBA). An icebreaker was placed purposely into the older pack ice north of Alaska in September 1997. The ship served as the base for experimenters who deployed extensive instrumentation to measure the atmosphere, ocean, and ice during a one-year period. My experiment will be to derive similar measurements (floe size, open water, temporal change) using spaceborne SAR data obtained during the summer of 1998, and compare these results with an ocean and ice model of summer melt. Additional information is contained in the original.

Holt, Benjamin↗
NASA NTRS2000

Sensitivity of Spacebased Microwave Radiometer Observations to Ocean Surface Evaporation

Ocean surface evaporation and the latent heat it carries are the major components of the hydrologic and thermal forcing on the global oceans. However, there is practically no direct in situ measurements. Evaporation estimated from bulk parameterization methods depends on the quality and distribution of volunteer-ship reports which are far less than satisfactory. The only way to monitor evaporation with sufficient temporal and spatial resolutions to study global environment changes is by spaceborne sensors. The estimation of seasonal-to-interannual variation of ocean evaporation, using spacebased measurements of wind speed, sea surface temperature (SST), and integrated water vapor, through bulk parameterization method,s was achieved with reasonable success over most of the global ocean, in the past decade. Because all the three geophysical parameters can be retrieved from the radiance at the frequencies measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, the feasibility of retrieving evaporation directly from the measured radiance was suggested and demonstrated using coincident brightness temperatures observed by SMMR and latent heat flux computed from ship data, in the monthly time scale. However, the operational microwave radiometers that followed SMMR, the Special Sensor Microwave/Imager (SSM/I), lack the low frequency channels which are sensitive to SST. This low frequency channels are again included in the microwave imager (TMI) of the recently launched Tropical Rain Measuring Mission (TRMM). The radiance at the frequencies observed by both TMI and SSM/I were simulated through an atmospheric radiative transfer model using ocean surface parameters and atmospheric temperature and humidity profiles produced by the reanalysis of the European Center for Medium Range Weather Forecast (ECMWF). From the same ECMWF data set, coincident evaporation is computed using a surface layer turbulent transfer model. The sensitivity of the radiance to evaporation over various seasons and geographic locations are examined. The microwave frequencies with radiance that are significant correlated with evaporation are identify and capability of estimating evaporation directly from TMI will be discussed.

Liu, Timothy W.↗
NASA NTRS2000

Producing Global Science Products for the Moderate Resolution Imaging Spectroradiometer (MODIS) in MODAPS

The MODerate resolution Imaging Spectroradiometer (MODIS) was launched on NASA's EOS-Terra spacecraft December 1999. With 36 spectral bands covering the visible, near wave and short wave infrared. MODIS produces over 40 global science data products, including sea surface temperature, ocean color, cloud properties, vegetation indices land surface temperature and land cover change. The MODIS Data Processing System (MODAPS) produces 400 GB/day of global MODIS science products from calibrated radiances generated in the Earth Observing System Data and Information System (EOSDIS). The science products are shipped to the EOSDIS for archiving and distribution to the public. An additional 200 GB of products are shipped each day to MODIS team members for quality assurance and validation of their products. In the sections that follow, we will describe the architecture of the MODAPS, identify processing bottlenecks encountered in scaling MODAPS from 50 GB/day backup system to a 400 GB/day production system and discuss how these were handled.

Masuoka, Edward J.↗
NASA NTRS1999

International Space Station Multi-Element Integrated Test

The International Space Station offers a unique challenge for integrated testing since the entire station is not launched as an integrated vehicle. The ISS design evolved for over 10 years from the station Freedom program that was based on a "ship and shoot" approach. Ship and shoot assumed the program would accept the hardware for launch and integrate the vehicle on orbit without any ground element-to-element integrated testing. Element-to-Element powered-on integrated testing is needed to identify operational problems on the ground rather than once the hardware is on orbit. The industry is accustomed to testing an integrated vehicle and then verifying it is ready for its operational missions. These tests require ground element emulators to represent on-orbit elements. The ISS Multi-Element Integrated Tests (MEIT) are element-to-element integrated tests bringing together hardware representing several flights. The major purpose of these tests is: 1) Element-to-Element interface compatibility, 2) Systems end-to-end operability and functionality and 3) utilize on-orbit procedures with the crew and mission control center. Execution of these tests is critical since the hardware is available for only a limited period of time. Test configurations are defined which test specific interfaces or functionality. These tests develop operational confidence in the Element-to-Element interfaces and identify major problems on the ground to avoid on-orbit anomalies that could threaten mission success, element survivability or assembly activities. This paper addresses the MEIT process, configurations and lessons-learned from these tests.

Filler, Russell E.↗
NASA NTRS2001

The Continuation of Cloud Statistics for NASA Climate Change Studies

The weather systems, cyclones, and anticyclones, along with air trajectories and cloud forms, are compared to past studies of the Arctic to assess compatibility of the four month study of the Arctic Cloud Experiment flights of the First ISCCP Regional Experiment (FIRE/ACE) with past climatologies. The frequency and movement of cyclones (lows) and anticyclones (highs) followed the general eastward and northeastward directions indicated by past studies. Most cyclones (lows) came from eastern Siberia and the Bering Sea to the south and moved north across the Bering Straight or Alaska into the Arctic Ocean. They generally weakened in central pressure as they moved poleward. Anticyclones (highs) were most common in the eastern Beaufort Sea near Canada in June and July as predicted from previous studies. However, many cyclones and anticyclones moved in westward directions which is rare in other latitudes. Erratic changes in shape and intensity on a daily basis also were observed. The National Center for Environmental Prediction (NCEP) analysis generally reflected the Surface Heat Budget in the Arctic (SHEBA) Ship World Meteorological Organization (WMO) observations which it used. However, NCEP temperatures were biased warm by 1.0 to 1.5 C in April and early May. In July when the surface temperature were at the freezing/thawing point, the NCEP analysis changed to a cold bias of -1.0 C. Dew points had smaller biases except for July where they were biased cold by -1.4 C. Wind speeds had a -2 m/s low bias for the six windiest days. Surface barometric pressures had consistently low biases from -1.2 to -2.8 hPa in all four months. Air parcel historical trajectories were mainly from the south or from local anticyclonic gyres in the Beaufort Sea. Most air came to the SHEBA Ship from the north Pacific Ocean or from Alaska and Canada and occasionally from eastern Siberia. Very few trajectories traced back across the pole to Europe and Central Asia. Cloud cover was high, as expected, from 69-86% of the time. Satellite data also indicate frequent stratus, altostratus, and cirrus clouds (occurring 61% of the time) above the expected boundary layer fog and Arctic stratus clouds.

Wylie, Donald P.↗
NASA NTRS2000

Automated Traffic Management System and Method

A data management system and method that enables acquisition, integration, and management of real-time data generated at different rates, by multiple heterogeneous incompatible data sources. The system achieves this functionality by using an expert system to fuse data from a variety of airline, airport operations, ramp control, and air traffic control tower sources, to establish and update reference data values for every aircraft surface operation. The system may be configured as a real-time airport surface traffic management system (TMS) that electronically interconnects air traffic control, airline data, and airport operations data to facilitate information sharing and improve taxi queuing. In the TMS operational mode, empirical data shows substantial benefits in ramp operations for airlines, reducing departure taxi times by about one minute per aircraft in operational use, translating as $12 to $15 million per year savings to airlines at the Atlanta, Georgia airport. The data management system and method may also be used for scheduling the movement of multiple vehicles in other applications, such as marine vessels in harbors and ports, trucks or railroad cars in ports or shipping yards, and railroad cars in switching yards. Finally, the data management system and method may be used for managing containers at a shipping dock, stock on a factory floor or in a warehouse, or as a training tool for improving situational awareness of FAA tower controllers, ramp and airport operators, or commercial airline personnel in airfield surface operations.

Glass, Brian J.↗
NASA NTRS2001

TRMM Validation: Integration of TRMM Satellite and Ground-Validation Data to Determine Tropical Heating

Steiner and Houze showed from ground validation data that the Tropical Rain Measuring Mission (TRMM) satellite Precipitation Radar's (PR's) twice daily only sampling should lead to an uncertainty of approximately 20% in rain estimates. They further showed that the uncertainties are smallest at the 5-7.5 km level. Schumacher and Houze used Kwajalein ground validation data to show that the TRMM PR misses only 2.3% of the near surface rainfall but does not see 46% of the area where rain occurs, because of the 17 dBZ PR reflectivity threshold. Houze discusses how the TRMM data extend earlier tropical convective studies to global coverage of the vertical profile of latent heating via the TRMM PR''s ability to distinguish and globally map convective and stratiform precipitation. Process studies carried out under this TRMM grant Yuter and Houze and Yuter et al. studied ship-based radar observations in the tropical eastern Pacific ITCZ. The eastern Pacific precipitation process is different from the western Pacific (the COARE area); rain is heavier but the clouds are not as deep. These process differences may affect the ability to remotely sense precipitation accurately in the two regions. Satellite microwave data were able to detect the precipitation as long as the rain areas exceeded 10 km in dimension. However, the microwave algorithms had difficulty distinguishing light and heavy rain. Satellite IR algorithms only partially detected the rain because the tops of the smaller and more short-lived rain clouds were sometimes not cold enough for the IR algorithms to detect them. Houze et al. focused on the west Pacific precipitating mesoscale convective systems and showed how their precipitation and internal dynamics vary in relation to the slowly varying large-scale heating-driven circulation, which has a structure described by a combination of Kelvin and Rossby wave response to the near-equatorial convective heating constituted by the mesoscale convective systems. Ship and aircraft radar data were used in this study.

Houze, Robert A., Jr.↗
NASA NTRS2002

Application of Mobile Router to Military Communications

Cisco Systems and NASA Glenn Research Center under a NASA Space Act Agreement have been performing joint networking research to apply Internet technologies and protocols to space-based communications. During this time, Cisco Systems developed the mobile-router which NASA and Cisco jointly tested. The early field trials of this technology have been successfully completed. The mobile-router is software code that resides in a network router. A Mobile-Router allows entire networks to roam while maintaining connectivity to the Internet. This router code is pertinent to a myriad of applications for both the government and commercial sectors. This technology will be applied to the wireless battlefield. NASA and the Department of Defense will utilize this technology for near-planetary observation and sensing spacecraft. It is the enabling technology for communication via the Internet or Intranets to aircraft. Information such as weather, air traffic control, voice and video can be easily and inexpensively transmitted to the aircraft using Internet protocols. The mobile router can be incorporated into emergency vehicles particularly ambulances and life-flight aircraft to provide real-time connectivity back to the hospital and healthcare experts. Commercial applications include entertainment services, IP telephone, and Internet connectivity for cruise ships, commercial shipping, tour busses, aircraft, and eventually cars. This paper will briefly describe the mobile router operation. An upcoming wide area network field test with application to US Coast Guard communications will be described. The paper will also highlight military and government networks that will benefit from the deployment of mobile router and the associated applications.

Stewart, David H.↗
NASA NTRS2002

Status and Progress on the Upgraded Infrared Spatial Interferometer

The U.C. Berkeley Infrared Spatial Interferometer is a two telescope stellar interferometer operating in the 9-12 micron atmospheric window, utilizing heterodyne detection with CO2 laser local oscillators. Science with the ISI has been focused on the measurements of the spatial distribution of dust and molecules around mass-losing late type stars, and more recently precision measurements of stellar diameters in the mid-infrared avoiding molecular lines. Also during the past few years, a NSF sponsored program of expansion from two to three telescopes has been underway. This expansion will allow the ISI to make visibility observations on three simultaneous baselines and a measure a closure phase. The third telescope was completed last year and shipped to Mt. Wilson, and more recently a Central Control Facility and Master Laser Oscillator Facility were also completed and recently shipped to Mt. Wilson. In this talk we report progress on this program and highlight some of the most recent astrophysical results.

Danchi, W. C.↗
NASA NTRS1994

Reflective Packaging

The aluminized polymer film used in spacecraft as a radiation barrier to protect both astronauts and delicate instruments has led to a number of spinoff applications. Among them are aluminized shipping bags, food cart covers and medical bags. Radiant Technologies purchases component materials and assembles a barrier made of layers of aluminized foil. The packaging reflects outside heat away from the product inside the container. The company is developing new aluminized lines, express mailers, large shipping bags, gel packs and insulated panels for the building industry.

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NASA NTRS1984

Firefighting Module

Firefly II pump module is NASA's Marshall Space Flight Center's commercial offshoot of a NASA/US Coast Guard program involving development of a lightweight, helicopter-transportable firefighting module for a quick response in combating shipboard or harbor fires. Operable on land or water, the Amphib One is equipped with 3 water cannons. When all 3 are operating, unit pumps more than 3,000 gallons a minute. Newly developed model used by U.S. Coast Guard can pump 5,000 gallons per minute. It was designed for applications such as firefighting onboard ship fires, emergency dockside water pumping, dewatering ships in danger of sinking, flood control, and emergency water supply at remote locations.

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NASA NTRS2002

Enhancement of Cloud Cover and Suppression of Nocturnal Drizzle in Stratocumulus Polluted by Haze

Recent satellite observations indicate a significant decrease of cloud water in ship tracks, in contrast to an ensemble of in situ ship-track measurements that show no average change in cloud water relative to the surrounding clouds. We find through large-eddy simulations of stratocumulus that the trend in the satellite data is likely an artifact of sampling only overcast clouds. The simulations instead show cloud cover increasing with droplet concentrations. Our simulations also show that increases in cloud water from drizzle suppression (by increasing droplet concentrations) are favored at night or at extremely low droplet concentrations.

Ackerman, Andrew S.↗
NASA NTRS2002

Convection and Easterly Wave Structure Observed in the Eastern Pacific Warm-Pool during EPIC-2001

During September-October 2001, the East Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System (EPIC-2001) ITCZ field campaign focused on studies of deep convection in the warm-pool region of the East Pacific. In addition to the TAO mooring array, observational platforms deployed during the field phase included the NOAA ship RN Ronald H. Brown, the NSF ship RN Horizon, and the NOAA P-3 and NCAR C-130 aircraft. This study combines C-band Doppler radar, rawinsonde, and surface heat flux data collected aboard the RN Brown to describe ITCZ convective structure and rainfall statistics in the eastern Pacific as a function of 3-5 day easterly wave phase. Three distinct easterly wave passages occurred during EPIC-2001. Wind and thermodynamic data reveal that the wave trough axes exhibited positively correlated U and V winds and a slight westward phase tilt with height. A relatively strong (weak) northeasterly deep tropospheric shear followed the trough (ridge) axis. Temperature and humidity perturbations exhibited mid-to upper level cooling (warming) and drying (moistening) in the northerly (trough and southerly) phase. At low levels warming (cooling) occurred in the northerly (southerly) phase with little change in the relative humidity, though mixed layer mixing ratios were larger during the northerly phase. When composited, radar, sounding, lightning and surface heat flux observations suggest the following systematic behavior as a function of wave phase: approximately zero to one quarter wavelength ahead of (behind) the wave trough in northerly (southerly) flow, larger (smaller) CAPE, lower (higher) CIN, weaker (stronger) tropospheric shear, higher (lower) conditional mean rain rates, higher (lower) lightning flash densities, and more (less) robust convective vertical structure occurred. Latent and sensible heat fluxes reached a minimum in the northerly phase and then increased through the trough, reaching a peak during the ridge phase (leading the peak in CAPE). From a radar echo coverage perspective, larger areas of light rain and slightly larger (10%) area averaged rain rates occurred in the vicinity of, and just behind, the trough axes in southerly flow. Importantly, the transition in convective structure observed across the trough axis when considered with the relatively small change in area mean rain rates suggests the presence of a transition in the vertical structure of diabatic heating across the easterly waves examined. The inferred transition in heating structure is supported by radar diagnosed divergence profiles that exhibit convective (stratiform) characteristics ahead of (behind) the trough.

Peterson, Walter A.↗
NASA NTRS1980

Liquefied Natural Gas Transfer

Chicago Bridge & Iron Company's tanks and associated piping are parts of system for transferring liquefied natural gas from ship to shore and storing it. LNG is a "cryogenic" fluid meaning that it must be contained and transferred at very low temperatures, about 260 degrees below Fahrenheit. Before the LNG can be pumped from the ship to the storage tanks, the two foot diameter transfer pipes must be cooled in order to avoid difficulties associated with sharp differences of temperature between the supercold fluid and relatively warm pipes. Cooldown is accomplished by sending small steady flow of the cryogenic substance through the pipeline; the rate of flow must be precisely controlled or the transfer line will be subjected to undesirable thermal stress.

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