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At least 181 records · Page 10

Thinking Outside of the Blue Marble: Novel Ocean Applications Using the VIIRS Sensor

While planning for future space-borne sensors will increase the quality, quantity, and duration of ocean observations in the years to come, efforts to extend the limits of sensors currently in orbit can help shed light on future scientific gains as well as associated uncertainties. Here, we present several applications that are unique to the polar orbiting Visual Infrared Imaging Radiometer Suite (VIIRS), each of which challenge the threshold capabilities of the sensor and provide lessons for future missions. For instance, while moderate resolution polar orbiters typically have a one day revisit time, we are able to obtain multiple looks of the same area by focusing on the extreme zenith angles where orbital views overlap, and pair these observations with those from other sensors to create pseudo-geostationary data sets. Or, by exploiting high spatial resolution (imaging) channels and analyzing patterns of synoptic covariance across the visible spectrum, we can obtain higher spatial resolution bio-optical products. Alternatively, non-traditional products can illuminate important biological interactions in the ocean, such as the use of the Day-Night-Band to provide some quantification of phototactic behavior of marine life along light polluted beaches, as well as track the location of marine fishing vessel fleets along ocean fronts. In this talk, we explore ways to take full advantage of the capabilities of existing sensors in order to maximize insights for future missions.

ocean color↗

Dustsonde and lidar measurements of stratospheric aerosols - A comparison

Comparison of lidar and in situ measurements of stratospheric aerosol profiles obtained by backscattered ruby laser light and by direct in situ sampling over Laramie, Wyoming, on two nights in mid-September 1972. The lidar backscattering and the particle number density profiles correlated well. Based on these initial comparative experiments, the ground-based lidar coupled with temperature soundings appears to be a possible method for determining the relative aerosol profile under given stratospheric loading conditions.

Northam, G. B.↗

Spaceborne SAR and sea ice

A number of remote sensing systems deployed in satellites to view the Earth which are successful in gathering data on the behavior of the world's snow and ice covers are described. Considering sea ice which covers over 10% of the world ocean, systems that have proven capable to collect useful data include those operating in the visible, near-infrared, infrared, and microwave frequency ranges. The microwave systems have the essential advantage in observing the ice under all weather and lighting conditions. Without this capability data are lost during the long polar night and during times of storm passage, periods when ice activity can be intense. The margins of the ice pack, a region of particular interest, is shrouded in cloud between 80 and 90% of the time.

Weeks, W. F.↗

Is 1220 Crocus a precessing, binary asteroid?

Photoelectric data of the asteroid 1220 Crocus over a 13 night period in 1984 revealed the presence of two separate periods. The light curves were indicative of a precessing body, but not one in free precession due to motions induced by a collision. Closer examinations revealed periods of 30.7 and 7.9 hr with amplitudes of 0.87 and 0.15 mag, respectively. An analysis of the source of an external torque which could be causing a forced precession led to the hypothesis that 1220 Crocus has a satellite. Verification of the binary asteroid configuration will depend on more detailed light curves, the possible modulation of the shorter period by the longer, and possible use of the Space Telescope.

Binzel, R. P.↗

A New Scientific use of Total Eclipses of the Moon: Studies of the Generation and Loss of Atmospheres of Primitives Bodies

This grant supported observational campaigns to record the size and brightness of the lunar atmosphere as seen in sodium gas (Na) emissions during the totality phase of lunar eclipses. Three eclipse events were attempted, two from the Mc Donald Observatory in Fort Davis Texas, and one from the site of Italy's Galileo National Telescope (GNT) in La Palma, in the Canary Islands. In all three cases, clear skies prevailed and excellent datasets were obtained. Following the observational component of the grant, a period of detailed processing and analysis began. Eclipse events were chosen for study because when the moon is in full phase it has been within the terrestrial magnetosphere for a few days, thereby shielded from solar wind impact upon its surface. Since sputtering of Na from the lunar regolith by solar wind particles had been proposed as a source of the Moon's atmosphere, this was a test of the mechanism. If the lunar Na appeared to be diminished in comparison to abundances seen at other phases (e.g., at quarter phase when the moon is directly in the solar wind), the solar wind sputtering would indeed be a major source of lunar Na. These experiments could not be conducted during any full moon night because scattering of bright moonlight is so strong that low-light-level imaging of the lunar atmosphere could not be achieved. Hence, the use of eclipses. The final result of these experiments was, for once, clear and unambiguous. The robust size and Na brightness levels measured during all of the eclipses showed that solar wind sputtering could not be a major source of the lunar atmosphere. A major paper on this conclusion was published in ICARUS, and an oral presentation of partial results given at the The Three Galileos conference in Padova (Italy) in January 1997 and at the DPS meeting in Cambridge, MA, in July 1997.

Mendillo, Michael↗

Visions of our Planet's Atmosphere, Land and Oceans: NASA/NOAA Electronic Theater 2002

The NASA/NOAA Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to the Olympic Medals Plaza, the new Gateway Center, and the University of Utah Stadium Site of the Olympic Opening and Closing Ceremonies in Salt Lake City. Fly in and through the Park City, and Snow Basin sites of the 2002 Winter Olympic Alpine Venues using 1 m IKONOS "Spy Satellite" data. See the four seasons of the Wasatch Front as observed by Landsat 7 at 15m resolution and watch the trees turn color in the Fall, snow come and go in the mountains and the reservoirs freeze and melt. Go back to the early weather satellite images from the 1960s and see them contrasted with the latest US and international global satellite weather movies Including hurricanes & "tornadoes". See the latest visualizations of spectacular images from NASA/NOAA remote sensing missions like Terra, GOES, TRMM, SeaWiFS, Landsat 7 including new 1 - min GOES rapid scan image sequences of Nov 9th 2001 Midwest tornadic thunderstorms and have them explained. See how High-Definition Television (HDTV) is revolutionizing the way we communicate science. (In cooperation with the American Museum of Natural History in NYC) See dust storms in Africa and smoke plumes from fires in Mexico. See visualizations featured on the covers Of Newsweek, TIME, National Geographic, Popular Science & on National & International Network TV. New computer software. tools allow us to roam & zoom through massive global images e.g. Landsat tours of the US, and Africa, showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the polar ice packs and the motion of gigantic Antarctic Icebergs from SeaWinds data. Spectacular new visualizations of the global atmosphere & oceans are shown. See vertexes and currents in the global oceans that bring up the nutrients to feed tin) algae and draw the fish, whales and fisherman. See the how the ocean blooms in response to these currents and El Nino/La Nina climate changes. See the city lights, fishing fleets, gas flares and biomass burning of the Earth at night observed by the "night-vision" DMSP military satellite. The demonstration is interactively driven by a SGI Octane Graphics Supercomputer with two CPUs, 4 Gigabytes of RAM and 0.5 Terabyte of disk using two projectors across a super sized panoramic 48 foot screen. In addition new HDTV technology will be demonstrated from a portable computer server.

Hasler, A. F.↗

Visions of our Planet's Atmosphere, Land and Oceans: NASA/NOAA Electronic-Theater 2002. Spectacular Visualizations of our Blue Marble

Spectacular Visualizations of our Blue Marble The NASA/NOAA Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to the 2002 Winter Olympic Stadium Site of the Olympic Opening and Closing Ceremonies in Salt Lake City. Fly in and through Olympic Alpine Venues using 1 m IKONOS "Spy Satellite" data. Go back to the early weather satellite images from the 1960s and see them contrasted with the latest US and international global satellite weather movies including hurricanes & "tornadoes". See the latest visualizations of spectacular images from NASA/NOAA remote sensing missions like Terra, GOES, TRMM, SeaWiFS, Landsat 7 including new 1 - min GOES rapid scan image sequences of Nov 9th 2001 Midwest tornadic thunderstorms and have them explained. See how High-Definition Television (HDTV) is revolutionizing the way we communicate science. (In cooperation with the American Museum of Natural History in NYC). See dust storms in Africa and smoke plumes from fires in Mexico. See visualizations featured on the covers of Newsweek, TIME, National Geographic, Popular Science & on National & International Network TV. New computer software tools allow us to roam & zoom through massive global images e.g. Landsat tours of the US, and Africa, showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the polar ice packs and the motion of gigantic Antarctic Icebergs from SeaWinds data. Spectacular new visualizations of the global atmosphere & oceans are shown. See vertexes and currents in the global oceans that bring up the nutrients to feed tiny algae and draw the fish, whales and fisherman. See the how the ocean blooms in response to these currents and El Nicola Nina climate changes. See the city lights, fishing fleets, gas flares and biomass burning of the Earth at night observed by the "night-vision" DMSP military satellite.

Hasler, A. F.↗

Visions of our Planet's Atmosphere, Land & Oceans

The NASA/NOAA Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to South Africa, Cape Town and Johannesburg using NASA Terra MODIS data, Landsat data and 1m IKONOS "Spy Satellite" data. Zoom in to any place South Africa using Earth Viewer 3D from Keyhole Inc. and Landsat data at 30 m resolution. Go back to the early weather satellite images from the 1960s and see them contrasted with the latest US and international global satellite weather movies including hurricanes & "tornadoes". See the latest visualizations of spectacular images from NASA/NOAA remote sensing missions like Terra, GOES, TRMM, SeaWiFS, Landsat 7 including 1 - min GOES rapid scan image sequences of Nov 9th 2001 Midwest tornadic thunderstorms and have them explained. See how High-Definition Television (HDTV) is revolutionizing the way we present science to the public. See dust storms and flooding in Africa and smoke plumes from fires in Mexico. See visualizations featured on the covers of Newsweek, TIME, National Geographic, Popular Science & on National & International Network TV. New computer software tools allow us to roam & zoom through massive global images e.g. Landsat tours of the US, and Africa, showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the north and south polar ice packs and with icebergs on the coasts of Greenland and off the coast of Antarctica. Spectacular new visualizations of the global land, atmosphere & oceans are shown. Listen to the pulse of our planet. See how land vegetation, ocean plankton, clouds and temperatures respond to the sun & seasons. See vortexes and currents in the global oceans that bring up the nutrients to feed tiny algae and draw the fish, whales and fisherman. See the how the ocean blooms in response to these currents and El Nino/La Nina climate changes. See the city lights, fishing fleets, gas flares and biomass burning of the Earth at night observed by the "night-vision" DMSP military satellite. The presentation will be made using the latest HDTV and video projection technology that is now done from a laptop computer through an entirely digital path.

Hasler, Arthur F.↗

An Hour of Spectacular Visualization

The NASA/NOAA Electronic Theater presents Earth science observations and visualizations from space in a historical perspective. Fly in from outer space to Athens and site of the 2004 Summer Olympics and the Far East using 1 m IKONOS "Spy Satellite" data. Contrast the 1972 Apollo 17 "Blue Marble" image of the Earth with the latest US and International global satellite images that allow us to view our Planet from any vantage point. See the latest spectacular images from NASA/NOAA/Commercial remote sensing missions like Terra, GOES, TRMM, SeaWiFS, & Landsat 7, QuickBird of the SE Asia Tsunami, devastation of Hurricane Katrina this year in New Orleans, and the LA/San Diego Fires of 2003. See how High Definition Television (HDTV) is revolutionizing the way we do science communication. Take the pulse of the planet on a daily, annual and 30-year time scale. See daily thunderstorms, the annual blooming of the northern hemisphere land masses and oceans, fires in Africa, dust storms in Iraq, and carbon monoxide exhaust from global burning. See visualizations featured on Newsweek, TIME, National Geographic, Popular Science covers & National & International Network TV. Spectacular new global visualizations of the observed and simulated atmosphere & oceans are shown. See the currents and vortexes in the oceans that bring up the nutrients to feed tiny plankton and draw the fish, whales and fishermen. See the how the ocean blooms in response to El Nino/La Nina climate changes. The Etheater will be presented using the latest High Definition TV (HDTV) and video projection technology on a large screen. See city lights around the globe and in your area observed by the "night-vision" DMSP satellite, Also see how Keyhole and Google Maps are using satellite and aerial photography to help you find your house and plan your vacation.

Hasler, Arthur F.↗

Comets: Very Eccentric Characters!

Comets occasionally appear in our night skies. We see them as bright or faint fuzzy balls of light, with one or two long tails streaming out. They look nothing like the stars, the moon, or any other object we see in the sky. That is because they really are quite different!

comets↗

SN2020bvc: A Broad-line Type Ic Supernova with a Double-peaked Optical Light Curve and a Luminous X-Ray and Radio Counterpart

We present optical, radio, and X-ray observations of SN 2020bvc (=ASASSN-20bs, ZTF 20aalxlis), a nearby (z = 0.0252; d = 114Mpc) broad-line (BL) Type Ic supernova (SN) and the first double-peaked Ic-BL discovered without a gamma-ray burst (GRB) trigger. Our observations show that SN 2020bvc shares several properties in common with the Ic-BL SN 2006aj, which was associated with the low-luminosity gamma-ray burst (LLGRB) 060218. First, the 10 GHz radio luminosity (L(radio) ≈ 10^(37) erg/s) is brighter than ordinary core-collapse SNe but fainter than LLGRB SNe such as SN 1998bw (associated with LLGRB 980425). We model our VLA observations (spanning 13–43 days) as synchrotron emission from a mildly relativistic (v ≳ 0.3c) forward shock. Second, with Swift and Chandra, we detect X-ray emission (L(X) ≈ 10^(41) erg/s) that is not naturally explained as inverse Compton emission or part of the same synchrotron spectrum as the radio emission. Third, high-cadence (6 × per night) data from the Zwicky Transient Facility (ZTF) show a double-peaked optical light curve, the first peak from shock cooling of extended low-mass material (mass Me < 10^(-2) Mꙩ at radius Re > 10^(12) cm) and the second peak from the radioactive decay of 56Ni. SN 2020bvc is the first double-peaked Ic-BL SN discovered without a GRB trigger, so it is noteworthy that it shows X-ray and radio emission similar to LLGRB SNe. For four of the five other nearby (z ≲ 0.05) Ic-BL SNe with ZTF high-cadence data, we rule out a first peak like that seen in SN 2006aj and SN 2020bvc, i.e., that lasts ≈1 day and reaches a peak luminosity M ≈ −18. Follow-up X-ray and radio observations of Ic-BL SNe with well-sampled early optical light curves will establish whether double-peaked optical light curves are indeed predictive of LLGRB-like X-ray and radio emission.

Anna Y. Q. Ho↗

Detection of 10 (10) GeV Cosmic Neutrinos with a Space Station

The potential value of SOCRAS (Space Observatory of Cosmic Ray Air Showers) for studying the highest energy cosmic rays, including the neutrinos produced in collisions of cosmic ray protons with photons of the 3 deg background radiation is examined. This instrument would look down at the atmosphere from a space station orbiting the Earth at an altitude of 500 to 600 km. During the night portion of each orbit, air showers would be imaged in the fluorescent light they produce. Progress toward the eventual realization of this scheme is described, including a suggestion by Torii for improving the vertical resolution, measurements of the terrestrial background light by Halverson, and especially an application of the LPM effect, expected to increase the sensitivity for upward moving neutrinos by several orders of magnitude.

Linsley, J.↗

STS-97 Crew Activity Report/Flight Day 11 Highlights

On this eleventh day of the STS-97 mission, Commander Brent W. Jett, Pilot Michael J. Bloomfield, and Mission Specialists Joseph R. Tanner, Carlos I. Noriega, and Marc Garneau remain docked with the International Space Station (ISS) on board the Endeavour Orbiter. Jett and Bloomfield are seen performing a check of the shuttle flight controls in preparation for tomorrow's landing. Jett, Noriega, and Tanner answer questions about the mission and the goals fulfilled. Footage shows the Earth at night as the camera on Endeavour sweeps the Mediterranean coastline, outlined by city lights, showing Spanish/French border, the French Riviera, the Alps, Italy, Switzerland, and the German/Austrian border.

Source record↗

Optical Microvariability of Blazars

We present the results of optical differential photometry of five blazers [PKS0219+428 (3C66A), PKS 0235+164 (AO 0235+16), H0414+019, PKS 0851+202 (OJ 187) and QSO 1807+698 (3C 371)] that were observed on 7 nights between November 05, 1997 and December 29, 1998, using the B and the V band filters. We have detected microvariations in four blazers (3C66A, AO 0235+16, H0414+019, and OJ 287). In addition, the light curve of AO 0235+16 has displayed a mini-flare when the brightness of this source was decreasing. Night-to-night variations have also been detected in 3C66A, H0414+019, and OJ 287. The results of our observations are discussed in the framework of accretion disk phenomena (magnetic flares or hot spots in accretion disks) and jet phenomena (plasma instabilities in jets).

Ghosh, K. K.↗

High- and low-altitude AVIRIS observations of nocturnal lighting

Elvidge et al. (1997) developed methods to locate and define the spatial extent of nocturnal lighting across large land areas using low-light imaging data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). This sensor has a unique capability to detect low levels of visible - near infrared radiance at night (Figure 1). The primary function of the DMSP-OLS is to provide global imagery of cloud cover. At night the observed visible - near infrared (VNR) radiance is intensified, for the purpose of cloud detection using moonlight. In addition to moonlit clouds, the light intensification makes it possible to detect VNIR emissions emanating from the earth's surface, from cities, towns, industrial sites, gas flares, and ephemeral events such as fires. In the latter part of this decade NOAA, NASA and DoD plan to fly a new sensor (Visible Infrared Imaging Radiometer Suite - VIJRS) which will continue the record of low-light imaging earth observations, with improved spatial and radiometric properties over the OLS.

Green, Robert O.↗

Sleep, Circadian Rhythms, and Performance During Space Shuttle Missions

Sleep and circadian rhythms may be disturbed during spaceflight, and these disturbances can affect crewmembers' performance during waking hours. The mechanisms underlying sleep and circadian rhythm disturbances in space are not well understood, and effective countermeasures are not yet available. We investigated sleep, circadian rhythms, cognitive performance, and light-dark cycles in five astronauts prior to, during, and after the 16-day STS-90 mission and the IO-day STS-95 mission. The efficacy of low-dose, alternative-night, oral melatonin administration as a countermeasure for sleep disturbances was evaluated. During these missions, scheduled rest activity cycles were 20-35 minutes shorter than 24 hours. Light levels on the middeck and in the Spacelab were very low; whereas on the flight deck (which has several windows), they were highly variable. Circadian rhythm abnormalities were observed. During the second half of the missions, the rhythm of urinary cortisol appeared to be delayed relative to the sleep-wake schedule. Performance during wakefulness was impaired. Astronauts slept only about 6.5 hours per day, and subjective sleep quality was lower in space. No beneficial effects of melatonin (0.3 mg administered prior to sleep episodes on alternate nights) were observed. A surprising finding was a marked increase in rapid eye movement (REM) sleep upon return to Earth. We conclude that these Space Shuttle missions were associated with circadian rhythm disturbances, sleep loss, decrements in neurobehavioral performance, and alterations in REM sleep homeostasis. Shorter than 24-hour rest-activity schedules and exposure to light-dark cycles inadequate for optimal circadian synchronization may have contributed to these disturbances.

Neri, David F.↗

Raman Lidar Measurements of Pinatubo Aerosols over Southeastern Kansas During November-december 1991

The eruptions of the Philippine volcano Pinatubo during June 1991 produced large amounts of stratospheric aerosols that could significantly affect earth's climate as well as trigger stratospheric ozone depletion through heterogeneous chemical reactions. Information regarding the physical and optical properties of these aerosols is required to quantify those effects. By measuring both the elastically backscattered signal and the inelastic signal produced by Raman scattering from nitrogen molecules, Raman lidar can provide some of this information. In this presentation we discuss Raman lidar measurements of the scattering ratio, backscattering, extinction, extinction/backscattering ratio, and optical thickness of the Pinatubo aerosols over southeastern Kansas made on 10 nights during November and December, 1991. The Raman lidar developed at GSFC is a trailer-based system which uses an XeF excimer laser to transmit light at 351 nm. The light backscattered by molecules and aerosols at this wavelength is detected as well as Raman scattered light from water vapor, nitrogen, and oxygen molecules. Since background skylights interfere with the detection of the Raman signals the data discussed in this paper were acquired only at night.

Ferrare, R. A.↗

Ion composition and drift observations in the nighttime equatorial ionosphere

The first in situ measurements of ion composition in the nighttime equatorial E and F region ionospheres (90-300 km) are presented and discussed. These profiles were obtained by two rocket-borne ion mass spectrometers launched from Thumba, India on March 9-10, 1970 at solar zenith angles of 112 deg and 165 deg. Ionosonde data established that the composition was measured at times bounding a period of F region downward drift. During this period the ions O(+) and N(+) were enhanced by one to three orders of magnitude between 220 and 300 km. Below the drift region (200 km), O(+) ceased to be the major ionic constituent, but the concentrations of O(+) and N(+) remained larger than predicted from known radiation sources and loss processes. Here also, both the O2(+) and NO(+) profiles retained nearly the same shape and magnitude throughout the night in agreement with theories assuming scattered UV radiation to be the maintaining source. Light metallic ions including Mg(+), Na(+) and possibly Si(+) were observed to altitude approaching 300 km, while the heavier ions Ca(+) and K(+) were seen in reduced quantity to 200 km. All metal ion profiles exhibited changes which can be ascribed to vertical drifting.

Goldberg, R. A.↗