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1

Verification of National Weather Service spot forecasts using surface observations  

NASA Astrophysics Data System (ADS)

Software has been developed to evaluate National Weather Service spot forecasts issued to support prescribed burns and early-stage wildfires. Fire management officials request spot forecasts from National Weather Service Weather Forecast Offices to provide detailed guidance as to atmospheric conditions in the vicinity of planned prescribed burns as well as wildfires that do not have incident meteorologists on site. This open source software with online display capabilities is used to examine an extensive set of spot forecasts of maximum temperature, minimum relative humidity, and maximum wind speed from April 2009 through November 2013 nationwide. The forecast values are compared to the closest available surface observations at stations installed primarily for fire weather and aviation applications. The accuracy of the spot forecasts is compared to those available from the National Digital Forecast Database (NDFD). Spot forecasts for selected prescribed burns and wildfires are used to illustrate issues associated with the verification procedures. Cumulative statistics for National Weather Service County Warning Areas and for the nation are presented. Basic error and accuracy metrics for all available spot forecasts and the entire nation indicate that the skill of the spot forecasts is higher than that available from the NDFD, with the greatest improvement for maximum temperature and the least improvement for maximum wind speed.

Lammers, Matthew Robert

2

Satellite-based observations of surface turbulent stress during severe weather  

E-print Network

Satellite-based observations of surface turbulent stress during severe weather Mark A. Bourassa and a vertical offset (i.e., displacement height) of the log-wind profile, due to wave modification The environment of severe marine weather is harsh: in situ and satellite observations of surface turbulent

3

Recovery of global surface weather observations for historical reanalyses and international users  

Microsoft Academic Search

Third International Atmospheric Circulation Reconstructions Over the Earth Initiative Workshop: Reanalysis and Applications; Baltimore, Maryland, 3-5 November 2010; The third Atmospheric Circulation Reconstructions over the Earth (ACRE) workshop advanced the goals of the international ACRE initiative (http:\\/\\/www.met-acre.org\\/) to undertake and facilitate the recovery of instrumental terrestrial and marine global surface weather observations underpinning global weather reconstructions and reanalyses spanning the

Rob Allan; Gil Compo; Jim Carton

2011-01-01

4

On Observing the Weather  

NSDL National Science Digital Library

In this article, Mount Washington Observatory meteorologist Tim Markle shares the ins and outs of his daily weather-observing routine and offers insights on making weather observations at home or at school.

Peter Crane

2004-05-01

5

Weather Observing Fundamentals  

NSDL National Science Digital Library

"Weather Observing Fundamentals" provides guidance for U.S. Navy Aerographer's Mates, Quartermasters, and civilian observers tasked with taking and reporting routine, special, and synoptic observations. Although the focus of this lesson is on shipboard observations, much of the content applies to land-based observing and reporting as well. The lesson details standard procedures for taking accurate weather observations and for encoding those observations on COMNAVMETOCCOM Report 3141/3. Exercises throughout the lesson and four weather identification drills at the end provide learners with opportunities to practice and build their skills. The lesson covers a large amount of content. You may wish to work through the material in multiple sessions.

2014-09-14

6

Evaluation of Two Ultrasonic Snow Depth Sensors for National Weather Service Automated Surface Observation System Sites  

NASA Astrophysics Data System (ADS)

In the late 1980's the National Weather Service (NWS) deployed the Automated Surface Observing System (ASOS) at airport observing sites, eliminating the need for human observers. At the time there were no reliable sensors to measure snow depth and the traditional snow measurements of 6 hour snowfall and snow water equivalent (SWE) were abandoned at most locations. The National Weather Service is currently exploring the feasibility of installing ultrasonic snow depth sensors at ASOS sites to restore snowfall measurements to the historic data record. In the 2003-2004 snow season testing of the Judd Communications ultrasonic depth sensor began at three sites: Fort Collins, CO; Stove Prairie, CO; and New Brunswick, OH. Preliminary results show that due to scattering of the sound pulse the Judd sensor performs poorly under windy conditions and when low density snow is present on the snow surface. In addition to the automated data, 6 and 24 hour manual measurements of snowfall, snow depth, snow water equivalent and gauge precipitation were collected. For the 2004-2005 snow season, 15 sites across the U.S. will test both the Judd Communications and the Campbell Scientific sensors. This poster will show three aspects of the project: i) the magnitude and characteristics of noise in the sensor data, ii) an algorithm to convert continuous sensor total snow depth data to the traditional NWS 6 hour snowfall measurements, and iii) a comparison of the performance of the two sensors.

Brazenec, W. A.; Doesken, N. J.; Fassnacht, S. R.

2004-12-01

7

On Observing the Weather  

ERIC Educational Resources Information Center

Rain, sun, snow, sleet, wind... the weather affects everyone in some way every day, and observing weather is a terrific activity to attune children to the natural world. It is also a great way for children to practice skills in gathering and recording information and to learn how to use simple tools in a standardized fashion. What better way to…

Crane, Peter

2004-01-01

8

Optimizing weather radar observations using an adaptive multiquadric surface fitting algorithm  

NASA Astrophysics Data System (ADS)

Real time forecasting of river flow is an essential tool in operational water management. Such real time modelling systems require well calibrated models which can make use of spatially distributed rainfall observations. Weather radars provide spatial data, however, since radar measurements are sensitive to a large range of error sources, often a discrepancy between radar observations and ground-based measurements, which are mostly considered as ground truth, can be observed. Through merging ground observations with the radar product, often referred to as data merging, one may force the radar observations to better correspond to the ground-based measurements, without losing the spatial information. In this paper, radar images and ground-based measurements of rainfall are merged based on interpolated gauge-adjustment factors (Moore et al., 1998; Cole and Moore, 2008) or scaling factors. Using the following equation, scaling factors (C(x?)) are calculated at each position x? where a gauge measurement (Ig(x?)) is available: Ig(x?)+-? C (x?) = Ir(x?)+ ? (1) where Ir(x?) is the radar-based observation in the pixel overlapping the rain gauge and ? is a constant making sure the scaling factor can be calculated when Ir(x?) is zero. These scaling factors are interpolated on the radar grid, resulting in a unique scaling factor for each pixel. Multiquadric surface fitting is used as an interpolation algorithm (Hardy, 1971): C*(x0) = aTv + a0 (2) where C*(x0) is the prediction at location x0, the vector a (Nx1, with N the number of ground-based measurements used) and the constant a0 parameters describing the surface and v an Nx1 vector containing the (Euclidian) distance between each point x? used in the interpolation and the point x0. The parameters describing the surface are derived by forcing the surface to be an exact interpolator and impose that the sum of the parameters in a should be zero. However, often, the surface is allowed to pass near the observations (i.e. the observed scaling factors C(x?)) on a distance a?K by introducing an offset parameter K, which results in slightly different equations to calculate a and a0. The described technique is currently being used by the Flemish Environmental Agency in an online forecasting system of river discharges within Flanders (Belgium). However, rescaling the radar data using the described algorithm is not always giving rise to an improved weather radar product. Probably one of the main reasons is the parameters K and ? which are implemented as constants. It can be expected that, among others, depending on the characteristics of the rainfall, different values for the parameters should be used. Adaptation of the parameter values is achieved by an online calibration of K and ? at each time step (every 15 minutes), using validated rain gauge measurements as ground truth. Results demonstrate that rescaling radar images using optimized values for K and ? at each time step lead to a significant improvement of the rainfall estimation, which in turn will result in higher quality discharge predictions. Moreover, it is shown that calibrated values for K and ? can be obtained in near-real time. References Cole, S. J., and Moore, R. J. (2008). Hydrological modelling using raingauge- and radar-based estimators of areal rainfall. Journal of Hydrology, 358(3-4), 159-181. Hardy, R.L., (1971) Multiquadric equations of topography and other irregular surfaces, Journal of Geophysical Research, 76(8): 1905-1915. Moore, R. J., Watson, B. C., Jones, D. A. and Black, K. B. (1989). London weather radar local calibration study. Technical report, Institute of Hydrology.

Martens, Brecht; Cabus, Pieter; De Jongh, Inge; Verhoest, Niko

2013-04-01

9

Weather induced effects on extensive air showers observed with the surface detector of the Pierre Auger Observatory  

E-print Network

The rate of events measured with the surface detector of the Pierre Auger Observatory is found to be modulated by the weather conditions. This effect is due to the increasing amount of matter traversed by the shower as the ground pressure increases and to the inverse proportionality of the Moliere radius to the air density near ground. Air-shower simulations with different realistic profiles of the atmosphere support this interpretation of the observed effects.

Carla Bleve; for the Pierre Auger Collaboration

2007-06-11

10

S-290 Unit 9: Observing the Weather  

NSDL National Science Digital Library

This webcast covers procedures for taking accurate weather observations using belt weather kits and descriptions of other common weather observing equipment used in fire weather. In addition, maintenance of the primary components of the belt weather kit are demonstrated.

2014-09-14

11

Monthly Weather Review Surface Microphysical Observations Within East Coast Winter Storms on Long Island,  

E-print Network

: Surface observations of ice habit and degree of riming were measured for twelve cyclone events over three accumulated during these storms, with an average degree of riming of 1.25 and snow-liquid ratio ranging from 3, dendrites, and plates and have similar vertical motion and synoptic characteristics inferred from 13-km

Yuter, Sandra

12

Observations of “fresh” and weathered surfaces on asteroid pairs and their implications on the rotational-fission mechanism  

NASA Astrophysics Data System (ADS)

The rotational-fission of a “rubble-pile” structured asteroid can result in an “asteroid pair” - two unbound asteroids sharing nearly identical heliocentric orbits. Models suggest that this mechanism exposes material from below the progenitor surface that previously had never have been exposed to the weathering conditions of space. Therefore, the surfaces of asteroid pairs offer the opportunity to observe non-weathered “fresh” spectra. Here we report near-infrared spectroscopic observations of 31 asteroids in pairs. In order to search for spectral indications of fresh surfaces we analyze their spectral slopes, parameters of their 1 ?m absorption band and taxonomic classification. Additionally, through backward dynamical integration we estimate the time elapsed since the disintegration of the pairs’ progenitors. Analyzing the 19 ordinary chondrite-like (S-complex) objects in our sample, we find two Q-type Asteroids (19289 and 54827) that are the first of their kind to be observed in the main-belt of asteroids over the full visible and near-infrared range. This solidly demonstrates that the Q-type taxonomy is not limited to the NEA population. The pairs in our sample present a range of fresh and weathered surfaces with no clear evidence for a correlation with the ages of the pairs. However, our sample includes “old” pairs (2 × 106 ? age ? 1 × 106 years) that present relatively low, meteoritic-like spectral slopes (<0.2% per ?m). This illustrates a timescale of at least ?2 myr before an object develops high spectral slope that is typical for S-type asteroids. We discuss three mechanisms that explain the existence of weathered pairs with young dynamical ages and find that the “secondary fission” model (Jacobson, S.-A., Scheeres, D.-J. [2011]. Icarus 214, 161-178) is the most robust with our observations. In this mechanism an additional and subsequent fission of the secondary component contributes the lion share of fresh material that re-settles on the primary’s surface and recoats it with fresh material. If the secondary breaks loose from the vicinity of the primary before its “secondary fission”, this main source of fresh dust is avoided. We prefer this secondary fission model since (i) the secondary members in our sample present “fresh” parameters that tend to be “fresher” than their weathered primaries; (ii) most of the fresh pairs in our sample have low size ratios between the secondary and the primary; (iii) 33% of the primaries in our sample are fresh, similar to the prediction set by the secondary fission model (Jacobson, S.-A., Scheeres, D.-J. [2011]. Icarus 214, 161-178); (iv) known satellites orbit two of the pairs in our sample with low size ratio (D2/D1) and fresh surface; (v) there is no correlation between the weathering state and the primary shape as predicted by other models.

Polishook, David; Moskovitz, Nicholas; Binzel, Richard P.; DeMeo, Francesca E.; Vokrouhlický, David; Žižka, Jind?ich; Oszkiewicz, Dagmara

2014-05-01

13

HISTORY OF WEATHER OBSERVATIONS MOUNT AUBURN, OHIO  

E-print Network

. This study of the history of Mount Auburn weather observations is one way to preserve that history The goal of this study is to document the primary weather observational history of Mount Auburn that recorded such an important block of knowledge of early Ohio climate. Climatic data from the weather

Maynard, J. Barry

14

SPACE WEATHER OBSERVING SYSTEMS: CURRENT CAPABILITIES AND  

E-print Network

- REPORT ON SPACE WEATHER OBSERVING SYSTEMS: CURRENT CAPABILITIES AND REQUIREMENTS FOR THE NEXT and Supporting Research National Space Weather Program Council Joint Action Group for Space Environmental Gap of the President #12;ii NATIONAL SPACE WEATHER PROGRAM COUNCIL (NSWPC) MR. SAMUEL P. WILLIAMSON, Chairman Federal

Schrijver, Karel

15

Observations and simulations improve space weather models  

E-print Network

- 1 - Observations and simulations improve space weather models June 25, 2014 Los Alamos with fast-moving particles and a space weather system that varies in response to incoming energy computer simulations of the space weather that can affect vital technology, communication and navigation

16

Observing Weather: Making the Invisible Visible  

NSDL National Science Digital Library

This presentation will help students understand that weather occurs at local, regional and global scales and that modern weather observation and forecasting makes use of both simple instruments and the most advanced technologies to measure, record and forecast the weather. They will learn the instruments and methods used to measure temperature, pressure, wind direction and speed, humidity, dew point, cloud types, and precipitation. They will also learn about the use of remotely sensed data from satellites to make weather maps and predictions.

Michael Passow

17

Statistics of link blockage due to cloud cover for free-space optical communications using NCDC surface weather observation data  

NASA Technical Reports Server (NTRS)

Cloud opacity is one of the main atmospheric physical phenomena that can jeopardize the successful completion of an optical link between a spacecraft and a ground station. Hence, the site location chosen for a telescope used for optical communications must rely on knowledge of weather and cloud cover statistics for the geographical area where the telescope itself is located.

Slobin, S. D.; Piazzolla, S.

2002-01-01

18

DETECTION OF A LARGE VARIATION IN THE DEGREE OF SPACE WEATHERING ON THE SURFACE OF ITOKAWA BY HAYABUSA/AMICA OBSERVATIONS. M. Ishiguro  

E-print Network

of micrometrorite and/or solar wind irradiation [1-3]. In the previous mission targets, the space-weathering effect is equipped with seven narrowband filters for the scientific observations as well as a wide-band filter

Hiroi, Takahiro

19

All-weather land surface skin temperatures from a combined analysis of microwave and infrared satellite observations  

Technology Transfer Automated Retrieval System (TEKTRAN)

The surface skin temperature (Ts) is a key parameter at the land-atmosphere interface. Upwelling longwave radiation directly epends upon Ts. Energy exchanges at the land-surface boundary are largely controlled by the difference between Ts and the surface air temperature, the air and the surface reac...

20

Observations of the radiation divergence in the surface layer and its implication for its parameterization in numerical weather prediction models  

Microsoft Academic Search

This paper presents the results of 5 months of in situ observations of the diurnal cycle of longwave radiative heating rate in the lower part of the atmospheric boundary layer over grassland, with a particular focus on nighttime conditions. The observed longwave radiative heating is minimal at the evening transition, with a median value of ?1.8 K h?1 between 1.3

G. J. Steeneveld; M. J. J. Wokke; C. D. Groot Zwaaftink; S. Pijlman; B. G. Heusinkveld; A. F. G. Jacobs; A. A. M. Holtslag

2010-01-01

21

Field Observations of Weathering and Mass Wasting  

NSDL National Science Digital Library

This activity requires students to locate local examples of physical and chemical weathering, as well mass wasting, for which they must identify the type of process involved and describe the resulting effects on landform development. The students must write up their observations in a brief, written report using a technical writing style, which must include labeled photographs and sketches that support their observations and descriptions.

Lisa Davis

22

Venus Surface Composition and Weathering  

NASA Astrophysics Data System (ADS)

Imagine interpreting the geologic history of the Earth from radar images at ~100 m/pixel, topography with a footprint of ~10 km and major-element analyses at 3 random sites. This is our challenge for Venus after Magellan. This abstract is a summary of a Venus III chapter, which will describe what we have learned about the Venus surface primarily from Venus Express (VEx), which has for the first time provided regional mapping of surface radiance that includes compositional variability. Critical to the interpretation of these data are measurements of the 1 ?m emissivity of rocks under Venus conditions and a better understanding of the chemistry of potential Venus surface-atmosphere interactions.

Gilmore, M.; Helbert, J.; Smrekar, S.; Treiman, A.

2014-04-01

23

Unified Surface Analysis Manual Weather Prediction Center  

E-print Network

the equator to the North Pole, including adjacent ocean areas. The Weather Prediction Center (WPC) and its on their regions of expertise. By 2002, this plan went into place between NHC, OPC, and WPC, with HFO joining the collaboration effort in 2003. The WPC contributes a surface analysis covering the area from roughly 30°N to 85°N

24

Widespread Surface Weathering on Early Mars  

NASA Astrophysics Data System (ADS)

The recent discovery of widespread hydrous clays on Mars indicates that diverse and widespread aqueous environments existed on Mars, from the surface to kilometric depths [1,2]. The study of the past habitability and past climates of the planet requires assessing the importance of sustained surface water vs. subsurface water in its aqueous history. Using remote sensing data, we propose that surface weathering existed on Mars, suggesting that Mars experienced durable episodes of sustained liquid water on its surface. Weathering profiles are identified as vertical sequences of Al-rich clays and Fe/Mg-rich clays in the top tens of meters of the surface, similar to cases of pedogenesis on Earth (e.g. [3,4]). Such localized clay sequences have been reported by other works in 3 regions of Mars [5-8] and a similar origin was also proposed. Their frequency is however likely underestimated due to limitations of orbital investigations and re-surfacing processes. A large survey of the CRISM dataset leaded to a down-selection of ~100 deposits with clear vertical sequences, widely distributed over the southern highlands and grouped in regional clusters [9]. These putative weathering sequences are found either on inter-crater plateaus, on the floor of craters and large basins, or on crater ejectas. We investigated the thickness of the altered sequences, the age of the altered units and the different geological contexts to further understand the weathering process(es). Using few HiRISE DEMs where possible, and CTX DEMs, we find that the thickness of the exposed Al clays is on average of the order of several meters to few tens of meters. The clay sequences reported here are consistent with terrestrial weathering sequences which form under wet climates over geological timescales (>105-107 years). The combined age assessment of the altered unit and the unaltered capping (where present) provides constraints on the age of the weathering itself. All investigated cases point to an active weathering limited to the late Noachian to early Hesperian. The widespread distribution of weathering sequences in different geologic contexts, and the consistency in their estimated ages are best explained if Mars experienced a period/periods between the middle Noachian and the early Hesperian during which climatic conditions allowed sustained liquid water flow on its surface, while the high degree of degradation of older terrains does not allow affirming nor infirming earlier surface weathering on Mars. Only the in-situ exploration of Phyllosian/Noachian terrains may provide an answer to this fundamental question. Some of the authors have received funding from the ERC (FP7/2007-2013)/ERC Grant agreement n° 280168. [1] Ehlmann B., et al. Nature, 479, 53-60 (2011). [2] Carter J., et al. JGR, 118, 831-858 (2013) [3] Velde B., et al. Ed. Springer, Berlin, (1995). [4] Wilson M. Clay Minerals, 39, 233-266 (2004). [5] Gaudin A., et al. Icarus, 216(1), 257-268 (2011). [6] Loizeau D., et al. Icarus, 205, 396-418 (2010). [7] Noe Dobrea E., et al. JGR, 115, E00D19 (2010). [8] Le Deit L., et al. JGR, 117, E00J05 (2012). [9] Carter J., et al. LPSC 2012, p.1755

Loizeau, Damien; Carter, John; Mangold, Nicolas; Poulet, François; Rossi, Angelo; Allemand, Pascal; Quantin, Cathy; Bibring, Jean-Pierre

2014-05-01

25

Widespread Surface Weathering on Early Mars  

NASA Astrophysics Data System (ADS)

The recent discovery of widespread hydrous clays on Mars indicates that diverse and widespread aqueous environments existed on Mars, from the surface to kilometric depths [1,2]. The study of the past habitability of the planet requires assessing the importance of sustained surface water vs. subsurface water in its aqueous history. Using remote sensing data, we propose that surface weathering existed on Mars, suggesting that Mars experienced durable episodes of sustained liquid water on its surface. Weathering profiles are identified as vertical sequences of Al-rich clays and Fe/Mg-rich clays in the top tens of meters of the surface, similar to cases of pedogenesis on Earth (e.g. [3,4]). Such localized clay sequences have been reported by other works in 3 regions of Mars [5-8] and a similar origin was also proposed. Their frequency is however likely underestimated due to limitations of orbital investigations and re-surfacing processes. A large survey of the CRISM dataset leaded to a down-selection of 104 deposits with clear vertical sequences, widely distributed over the southern highlands and grouped in regional clusters [9]. These putative weathering sequences are found either on inter-crater plateaus, on the floor of craters and large basins, or on crater ejectas. We investigated the thickness of the altered sequences, the age of the altered units and the different geological contexts to further understand the weathering process(es). Using few HiRISE DEMs where possible, and CTX DEMs, we find that the thickness of the exposed Al clays is on average of the order of several meters to few tens of meters. The clay sequences reported here are consistent with terrestrial weathering sequences which form under wet climates over geological timescales (> 105-107 years). The combined age assessment of the altered unit and the unaltered capping (where present) provides constraints on the age of the weathering itself. All investigated cases point to an active weathering limited to the late Noachian to early Hesperian. The widespread distribution of weathering sequences in different geologic contexts, and the consistency in their estimated ages are best explained if Mars experienced a period/periods between the middle Noachian and the early Hesperian during which climatic conditions allowed sustained liquid water flow on its surface, while the high degree of degradation of older terrains does not allow affirming nor infirming earlier surface weathering on Mars. Only the in-situ exploration of Phyllosian/Noachian terrains may provide an answer to this fundamental question. Some of the authors have received funding from the European Research Council (FP7/2007-2013)/ERC Grant agreement n° 280168. [1] Ehlmann B., et al. Nature, 479, 53-60 (2011). [2] Carter J., et al. JGR, 118, 831-858 (2013) [3] Velde B., et al. Ed. Springer, Berlin, (1995). [4] Wilson M. Clay Minerals, 39, 233-266 (2004). [5] Gaudin A., et al. Icarus, 216(1), 257-268 (2011). [6] Loizeau D., et al. Icarus, 205, 396-418 (2010). [7] Noe Dobrea E., et al. JGR, 115, E00D19 (2010). [8] Le Deit L., et al. JGR, 117, E00J05 (2012). [9] Carter J., et al. LPSC 2012, p.1755

Loizeau, D.; Carter, J.; Mangold, N.; Poulet, F.; Rossi, A.; Allemand, P.; Quantin, C.; Bibring, J.

2013-12-01

26

Evaluating climate models: Should we use weather or climate observations?  

SciTech Connect

Calling the numerical models that we use for simulations of climate change 'climate models' is a bit of a misnomer. These 'general circulation models' (GCMs, AKA global climate models) and their cousins the 'regional climate models' (RCMs) are actually physically-based weather simulators. That is, these models simulate, either globally or locally, daily weather patterns in response to some change in forcing or boundary condition. These simulated weather patterns are then aggregated into climate statistics, very much as we aggregate observations into 'real climate statistics'. Traditionally, the output of GCMs has been evaluated using climate statistics, as opposed to their ability to simulate realistic daily weather observations. At the coarse global scale this may be a reasonable approach, however, as RCM's downscale to increasingly higher resolutions, the conjunction between weather and climate becomes more problematic. We present results from a series of present-day climate simulations using the WRF ARW for domains that cover North America, much of Latin America, and South Asia. The basic domains are at a 12 km resolution, but several inner domains at 4 km have also been simulated. These include regions of complex topography in Mexico, Colombia, Peru, and Sri Lanka, as well as a region of low topography and fairly homogeneous land surface type (the U.S. Great Plains). Model evaluations are performed using standard climate analyses (e.g., reanalyses; NCDC data) but also using time series of daily station observations. Preliminary results suggest little difference in the assessment of long-term mean quantities, but the variability on seasonal and interannual timescales is better described. Furthermore, the value-added by using daily weather observations as an evaluation tool increases with the model resolution.

Oglesby, Robert J [ORNL; Erickson III, David J [ORNL

2009-12-01

27

Evaluating Climate Models: Should We Use Weather or Climate Observations?  

NASA Astrophysics Data System (ADS)

Calling the numerical models that we use for simulations of climate change 'climate models' is a bit of a misnomer. These 'general circulation models' (GCMs, AKA global climate models) and their cousins the 'regional climate models' (RCMs) are actually physically-based weather simulators. That is, these models simulate, either globally or locally, daily weather patterns in response to some change in forcing or boundary condition. These simulated weather patterns are then aggregated into climate statistics, very much as we aggregate observations into 'real climate statistics'. Traditionally, the output of GCMs has been evaluated using climate statistics, as opposed to their ability to simulate realistic daily weather observations. At the coarse global scale this may be a reasonable approach, however, as RCM's downscale to increasingly higher resolutions, the conjunction between weather and climate becomes more problematic. We present results from a series of present-day climate simulations using the WRF ARW for domains that cover North America, much of Latin America, and South Asia. The basic domains are at a 12 km resolution, but several inner domains at 4 km have also been simulated. These include regions of complex topography in Mexico, Colombia, Peru, and Sri Lanka, as well as a region of low topography and fairly homogeneous land surface type (the U.S. Great Plains). Model evaluations are performed using standard climate analyses (e.g., reanalyses; NCDC data) but also using time series of daily station observations. Preliminary results suggest little difference in the assessment of long-term mean quantities, but the variability on seasonal and interannual timescales is better described. Furthermore, the value-added by using daily weather observations as an evaluation tool increases with the model resolution.

Oglesby, R. J.; Rowe, C. M.; Maasch, K. A.; Erickson, D. J.; Hays, C.

2009-12-01

28

Estimation of land surface fluxes using MOIDS and weather satellites  

NASA Astrophysics Data System (ADS)

Detailed knowledge of land surface fluxes, especially latent heat flux (i.e. land surface evapotranspiration), is important for understanding land-atmosphere interactions, and for agricultural applications such as irrigation water management. The unprecedented spatial and temporal coverage of Moderate Resolution Imaging Spectroradiometer (MODIS) data offer the potential to estimate surface radiation (shortwave, longwave and net radiation) and sensible and latent heat fluxes over large heterogeneous areas. However, an exclusively MODIS-based strategy is limited by cloud cover and the twice daily MODIS overpass frequency, and therefore works best for instantaneous estimates under clear sky conditions. A simple scheme that uses radiation data derived from observations from geostationary weather satellites (as well as some products from polar orbiting weather satellites) to augment the MODIS data is proposed to estimate all weather daily land surface sensible and latent heat fluxes. It provides continuous daily land surface flux maps over large heterogeneous domains with fine spatial resolution. Radiation data derived directly from the Geostationary Operational Environmental Satellites (GOES) and derived products archived by the International Satellite Cloud Climatology Project (ISCCP) were used to estimate land surface fluxes over the conterminous U.S. The estimated surface radiation components and sensible and latent heat fluxes were evaluated using in situ observations at the AmeriFlux towers. Preliminary results show that both the GOES-derived and ISCCP data are in good agreement with ground-based observations for both clear sky and overcast days. In general, use of weather satellite data allows leveraging of MODIS data to produce credible estimates of net radiation and sensible and latent heat fluxes under all weather conditions.

Tang, Q.; Lettenmaier, D. P.

2010-12-01

29

Weather  

NSDL National Science Digital Library

You will learn how to describe and observe changes in weather patterns by completing the following activities. The students will record and report changes in weather on their data sheet. The Process: Read the information on How Air Pressure Affects You. In this article you will see the term barometer. Write its definition. Now look over Weather Facts. Now go to Investigate Climate Conditions and use the weather maker to observe the effects of certain changes. Answer the questions: How much of a change in temperature is needed to make it ...

Ms. Lauren

2010-11-17

30

Ornithology Based on Linking Bird Observations with Weather Data  

E-print Network

Ornithology Based on Linking Bird Observations with Weather Data Mikko Koho1,2 , Eero Hyv¨onen2 results of a use case of Linked Data for eScience, where 0.5 million rows of bird migration observations over 30 years time span are linked with 0.1 million rows of related weather observations and a bird

Hyvönen, Eero

31

Surface Landing Site Weather Analysis for Constellation Program  

NASA Technical Reports Server (NTRS)

Weather information is an important asset for NASA's Constellation Program in developing the next generation space transportation system to fly to the International Space Station, the Moon and, eventually, to Mars. Weather conditions can affect vehicle safety and performance during multiple mission phases ranging from pre-launch ground processing to landing and recovery operations, including all potential abort scenarios. Meteorological analysis is an important contributor, not only to the development and verification of system design requirements but also to mission planning and active ground operations. Of particular interest are the surface atmospheric conditions at both nominal and abort landing sites for the manned Orion capsule. Weather parameters such as wind, rain, and fog all play critical roles in the safe landing of the vehicle and subsequent crew and vehicle recovery. The Marshall Space Flight Center Natural Environments Branch has been tasked by the Constellation Program with defining the natural environments at potential landing zones. Climatological time series of operational surface weather observations are used to calculate probabilities of occurrence of various sets of hypothetical vehicle constraint thresholds, Data are available for numerous geographical locations such that statistical analysis can be performed for single sites as well as multiple-site network configurations. Results provide statistical descriptions of how often certain weather conditions are observed at the site(s) and the percentage that specified criteria thresholds are matched or exceeded. Outputs are tabulated by month and hour of day to show both seasonal and diurnal variation. This paper will describe the methodology used for data collection and quality control, detail the types of analyses performed, and provide a sample of the results that can be obtained,

Altino, Karen M.; Burns, K. Lee

2008-01-01

32

Observe the effects of mechanical weathering  

NSDL National Science Digital Library

In this interactive Earth science resource, students are first presented with six photographs, each featuring a different mechanical weathering event in which rock is broken down. Examples of the events include road damage due to ice heaving and the expansion of cracks in rocks due to tree growth. Students are instructed to click on each labeled image to see an enlarged version of it. In the enlarged view, brief text, often accompanied by visual cues such as arrows, explains the physical weathering process shown. Copyright 2005 Eisenhower National Clearinghouse

TERC. Center for Earth and Space Science Education

2003-01-01

33

Evidence of Space Weathering Processes Across the Surface of Vesta  

NASA Astrophysics Data System (ADS)

As NASA's Dawn spacecraft explores the surface of Vesta, it has become abundantly clear that Vesta is like no other planetary body visited to date. Dawn is collecting global data at increasingly higher spatial resolution during its one-year orbital mission. The bulk properties of Vesta have previously been linked to the HED meteorites through remote mineral characterization of its surface from Earth-based spectroscopy. A principal puzzle has been why Vesta exhibits relatively unweathered diagnostic optical features compared to other large asteroids. Is this due to the composition of this proto-planet or the space environment at Vesta? Alteration or weathering of materials in space normally develops as the products of several processes accumulate on the surface or in an evolving particulate regolith, transforming the bedrock into fragmental material with properties that may be measurably different from the original. Data from Dawn reveal that the regolith of Vesta is exceptionally diverse. Regional surface units are observed that have not been erased by weathering with time. Several morphologically-fresh craters have excavated bright, mafic-rich materials and exhibit bright ray systems. Some of the larger craters have surrounding subdued regions (often asymmetric) that are lower in albedo and relatively red-sloped in the visible while exhibiting weaker mafic signatures. Several other prominent craters have rim exposures containing very dark material and/or display a system of prominent dark rays. Most, but not all, dark areas associated with craters exhibit significantly lower spectral contrast, suggesting that either a Vesta lithology with an opaque component has been exposed locally or that the surface has been contaminated by a relatively dark impactor. Similarly, most, but not all, bright areas associated with craters exhibit enhanced mafic signatures compared to surroundings. On a regional scale, the large south polar structure and surrounding terrain exhibit relatively strong mafic absorption features, suggesting either a concentration of mafic materials or that materials exposed have been less affected by space weathering products. These combined initial observations indicate some space weathering processes are active in this part of the main asteroid belt, but are highly variable across the surface of Vesta. Such processes include: impacts from wandering asteroidal debris and local mixing at both micro- and macro-scales, irradiation by solar wind and galactic particles, production and distribution of impact breccias or melt products, and local movement of materials to gravity lows (gradual as well as sudden).

Pieters, C. M.; Blewett, D. T.; Gaffey, M.; Mittlefehldt, D. W.; De sanctis, M.; Reddy, V.; Coradini, A.; Nathues, A.; Denevi, B. W.; Li, J.; McCord, T. B.; Marchi, S.; Palmer, E. E.; Sunshine, J. M.; Filacchione, G.; Ammannito, E.; Raymond, C. A.; Russell, C. T.

2011-12-01

34

Evidence of Space Weathering Processes Across the Surface of Vesta  

NASA Technical Reports Server (NTRS)

As NASA s Dawn spacecraft explores the surface of Vesta, it has become abundantly clear that Vesta is like no other planetary body visited to date. Dawn is collecting global data at increasingly higher spatial resolution during its one-year orbital mission. The bulk properties of Vesta have previously been linked to the HED meteorites through remote mineral characterization of its surface from Earth-based spectroscopy. A principal puzzle has been why Vesta exhibits relatively unweathered diagnostic optical features compared to other large asteroids. Is this due to the composition of this proto-planet or the space environment at Vesta? Alteration or weathering of materials in space normally develops as the products of several processes accumulate on the surface or in an evolving particulate regolith, transforming the bedrock into fragmental material with properties that may be measurably different from the original. Data from Dawn reveal that the regolith of Vesta is exceptionally diverse. Regional surface units are observed that have not been erased by weathering with time. Several morphologically-fresh craters have excavated bright, mafic-rich materials and exhibit bright ray systems. Some of the larger craters have surrounding subdued regions (often asymmetric) that are lower in albedo and relatively red-sloped in the visible while exhibiting weaker mafic signatures. Several other prominent craters have rim exposures containing very dark material and/or display a system of prominent dark rays. Most, but not all, dark areas associated with craters exhibit significantly lower spectral contrast, suggesting that either a Vesta lithology with an opaque component has been exposed locally or that the surface has been contaminated by a relatively dark impactor. Similarly, most, but not all, bright areas associated with craters exhibit enhanced mafic signatures compared to surroundings. On a regional scale, the large south polar structure and surrounding terrain exhibit relatively strong mafic absorption features, suggesting either a concentration of mafic materials or that materials exposed have been less affected by space weathering products. These combined initial observations indicate some space weathering processes are active in this part of the main asteroid belt, but are highly variable across the surface of Vesta. Such processes include: impacts from wandering asteroidal debris and local mixing at both micro- and macro-scales, irradiation by solar wind and galactic particles, production and distribution of impact breccias or melt products, and local movement of materials to gravity lows (gradual as well as sudden).

Pieters, Carle M.; Blewett, David T.; Gaffey, Michael; Mittlefehldt, David W.; CristinaDeSanctis, Maria; Reddy, Vishnu; Coradini, Angioletta; Nathues, Andreas; Denevi, Brett W.; Li, Jian-Yang; McCord, Thomas B.; Marchi, Simone; Palmer, Eric E.; Sunshine, Jessica M.; Filacchione, Gianrico; Ammannito, Eleonora; Raymond, Carol A.; Russell, Christopher T.

2011-01-01

35

Rock Rinds at Meridiani and Surface Weathering Phenomena  

NASA Astrophysics Data System (ADS)

The Rock Abrasion Tool (RAT) on the Mars rover Opportunity can brush away surface dust and grind away outcrop surface, exposing presumably less altered rock at depths of several mm. Alpha particle X-ray spectrometer (APXS) and Moessbauer spectrometer (MB) analyses of pre- and post-RAT targets, thus, provide information on the chemical nature of weathering of Meridiani outcrop rocks. To date, Opportunity has analyzed some 25 undisturbed rock surfaces, brushed and then analyzed 7 more, and ground 23 targets for IDD analysis. Panoramic camera images show that outcrop surfaces are typically either buff or purple (as viewed in bands centered at 673, 535, and 432 nm, Farrand et al., JGR, in press). Relatively flat surfaces that are approximately parallel to the ground are typically buff, whereas those that slope steeply tend to be purple. Surfaces of rock interiors ground by the RAT are also commonly purple. Spectrally, these color differences correspond to more oxidized (buff) and less oxidized (purple), and appear to relate to the degree of eolian abrasion. Flat-lying surfaces are not eroded as quickly, thus surfaces chemically weathered by exposure to tenuous atmospheric vapor may be preserved. These observations are consistent with in-situ analyses of rock surfaces and interiors. Compared to interiors, rock surfaces have about 1/3 less S, and in general, surface compositions lie between those of rock interiors and average surface soil. In detail, they differ from soil-rock mixtures as follows: surfaces are relatively depleted in Mg, Fe, Mn, Ti, and Cr, and they are enriched in Al, Na, K, P, Cl, and Si. From MB analyses, surfaces are richer (compared to soil-rock mixtures) in oxidized Fe phases and poorer in magnetite, olivine, and pyroxene. Morphologically, numerous flat-lying rocks and outcrop surfaces that are at or near the ground surface have a rind of erosionally resistant material. Such rinds are also chemically distinct from outcrop interiors. A rind/subjacent rock pair analyzed in detail was "Lemon Rind" and "Strawberry," ca. sols 555-560. The rind is depleted in S (balanced mainly by increased Si and Al) and, compared to a soil-rock mixture, it is depleted in Mg, Ti, Cr, Mn, and slightly in Fe, and it is enriched in Na, Cl, K, and P. Differences between rock surfaces and interiors, and between hardened weathering rinds and rock interiors, are consistent with loss of Mg-sulfate, oxidation of mafic minerals, enrichment of siliciclastic material, e.g., feldspar, and enrichment in chloride. These changes are consistent with slow rates of chemical weathering via interaction with small amounts of atmospheric water vapor or condensation. Erosionally resistant rinds may be related to preservation of aqueous condensate by a thin cover of soil on flat, near-surface rocks.

Jolliff, B.; Knoll, A.; Farrand, W.; Sullivan, R.

2006-12-01

36

Measuring stone weathering in cities: Surface reduction on marble monuments  

SciTech Connect

The purpose of this study was to establish whether measurements of stone weathering recorded by different observers could be aggregated into a simple data base for evaluating pollution effects on calcareous building stone. Apparent differences in recorded weathering rates on marble tombstones were here found to be partly a result of lettering size measured, measuring devices used, and individual observers.

Dragovich, D. (Univ. of Sydney, New South Wales (Australia))

1987-01-01

37

Observing Weather in Venus's Lower Atmosphere  

NASA Astrophysics Data System (ADS)

The rotation rate of Venus's sulfuric acid clouds is roughly 60 times greater than that of the solid surface, a phenomenon which is only partially understood. To help learn more about the details of the cloud motions, we observed Venus on three occasions near the past two inferior conjunctions at 2.3 microns, a window which transmits thermal radiation emanating from the lower scale heights of the atmosphere. Clouds block the thermal radiation in this wavelength band and show up as silhouettes on Venus's night side. We tracked atmospheric features to estimate their rates and directions. Several previous investigators have used 2.3 micron imaging to track Venus's clouds (e.g., Carlson et al. 1991, Crisp et al. 1991, Chanover et al. 1998). We compare our results to these previous investigations and to a solid-body rotator. We find no clear trend relating rotation rate to latitude. Instead, we often see local features with different rotation rates and different meridional directions from their neighbors within a latitudinal zone. These motions suggest that we are seeing snapshots of eddies in the mid-latitudes. Thick cloud cover is nearly always present at the equatorial latitudes and at both poles. The intermediate latitudes show thin cloud cover which is often broken into several narrow latitudinal ``zones,'' although these zones are certainly unlike belts and zones seen on Jupiter and Saturn, if only because (a) they are ephemeral on timescales of days and (b) they often have orientations that are up to 15 degrees away from the horizontal. As Crisp et al. (1991) suggest, these clearer regions could be the result of downwelling, possibly a manifestation of Hadley cells in the lower cloud deck. In approximately ten percent of our images we see turbulent-looking edges of the cloudy equatorial region, suggesting significant shear between adjacent latitudinal zones. Mark Bullock acknowledges support from NASA's Planetary Atmospheres and NSF's Planetary Astronomy programs References Carlson, R.W., K.H. Baines, T. Encrenaz, F.W. Tay-lor, P. Drossart, L.W. Kamp, J.B. Pollack, E. Lellouch, A.D. Collard, S.B. Calcutt, D.H. Grinspoon, P.R. Weissman, W.D. Smythe, A.C. Ocampo, G.E. Danielson, F.P. Fanale, T.V. Johnson, H.H. Kieffer, D.L. Matson, T.B. McCord, and L.A. Soderblom, Galileo infrared imaging spectrometer measurements at Venus, Science, 253, 1541-1548, 1991. Chanover, N.J., D.A. Glenar, and J.J. Hillman, Multispectral near-IR imaging of Venus nightside cloud features, Journal of Geophysical Research, 103, 31,335-31,348, 1998. Crisp, D., S. McMuldroch, S.K. Stephens, W.M. Sinton, B. Ragent, K.W. Hodapp, R.G. Probst, L.R. Doyle, D.A. Allen, and J. Elias, Ground-based near-infrared imaging observations of Venus during the Galileo encounter, Science, 253, 1538-1541, 1991b.

Young, E. F.; Bullock, M. A.; Chanover, N. J.; Lemmon, M. T.

2003-05-01

38

Generation of Multivariate Surface Weather Series with Use of the Stochastic Weather Generator Linked to Regional Climate Model  

NASA Astrophysics Data System (ADS)

The regional-scale simulations of weather-sensitive processes (e.g. hydrology, agriculture and forestry) for the present and/or future climate often require high resolution meteorological inputs in terms of the time series of selected surface weather characteristics (typically temperature, precipitation, solar radiation, humidity, wind) for a set of stations or on a regular grid. As even the latest Global and Regional Climate Models (GCMs and RCMs) do not provide realistic representation of statistical structure of the surface weather, the model outputs must be postprocessed (downscaled) to achieve the desired statistical structure of the weather data before being used as an input to the follow-up simulation models. One of the downscaling approaches, which is employed also here, is based on a weather generator (WG), which is calibrated using the observed weather series and then modified (in case of simulations for the future climate) according to the GCM- or RCM-based climate change scenarios. The present contribution uses the parametric daily weather generator M&Rfi to follow two aims: (1) Validation of the new simulations of the present climate (1961-1990) made by the ALADIN-Climate/CZ (v.2) Regional Climate Model at 25 km resolution. The WG parameters will be derived from the RCM-simulated surface weather series and compared to those derived from observational data in the Czech meteorological stations. The set of WG parameters will include selected statistics of the surface temperature and precipitation (characteristics of the mean, variability, interdiurnal variability and extremes). (2) Testing a potential of RCM output for calibration of the WG for the ungauged locations. The methodology being examined will consist in using the WG, whose parameters are interpolated from the surrounding stations and then corrected based on a RCM-simulated spatial variability. The quality of the weather series produced by the WG calibrated in this way will be assessed in terms of selected climatic characteristics focusing on extreme precipitation and temperature characteristics (including characteristics of dry/wet/hot/cold spells). Acknowledgements: The present experiment is made within the frame of projects ALARO (project P209/11/2405 sponsored by the Czech Science Foundation), WG4VALUE (project LD12029 sponsored by the Ministry of Education, Youth and Sports) and VALUE (COST ES 1102 action).

Dubrovsky, M.; Farda, A.; Huth, R.

2012-12-01

39

Titan's seasonal weather patterns, associated surface modification, and geological implications  

NASA Astrophysics Data System (ADS)

Model predictions [e.g., 1-3] and observations [e.g., 4,5] illustrate changes in Titan's weather patterns related to the seasons (Fig. 1). In two cases, surface changes were documented following large cloud outbursts (Figs. 2, 3): the first in Arrakis Planitia at high southern latitudes in Fall 2004, during Titan's late southern summer [6]; and the second at lows southern latitudes in Concordia and Hetpet Regiones, Yalaing Terra (Fig. 3), and Adiri, in Fall 2010, just over a year after Titan's northern vernal equinox [4, 7, 8]. Not only do these storms demonstrate Titan's atmospheric conditions and processes, they also have important implications for Titan's surface process, its methane cycle, and its geologic history.

Turtle, E. P.; Perry, J. E.; Barnes, J. W.; McEwen, A. S.; Barbara, J. M.; Del Genio, A. D.; Hayes, A. G.; West, R. A.; Lorenz, R. D.; Schaller, E. L.; Lunine, J. I.; Ray, T. L.; Lopes, R. M. C.; Stofan, E. R.

2013-09-01

40

Interpreting a Weathered Mars: Investigating the Effects of Weathering on Spectroscopic Observations Through Laboratory Study  

Microsoft Academic Search

Infrared spectroscopy is a critical tool for Martian mineralogy. Because it is crucial to evaluate the history of water on Mars, mineralogical study of weathering and alteration is among the most important topics of Mars spectroscopy. The state of alteration of the Martian surface is evaluated by the presence or absence of alteration phases and their overall abundance. Interpretations of

M. D. Kraft; T. G. Sharp; J. R. Michalski; E. B. Rampe

2007-01-01

41

A New Perspective on Surface Weather Maps  

ERIC Educational Resources Information Center

A two-dimensional weather map is actually a physical representation of three-dimensional atmospheric conditions at a specific point in time. Abstract thinking is required to visualize this two-dimensional image in three-dimensional form. But once that visualization is accomplished, many of the meteorological concepts and processes conveyed by the…

Meyer, Steve

2006-01-01

42

Weather  

NSDL National Science Digital Library

This lesson is written for fourth grade students. Students will explore weather and the effects it has on their lives. What is weather? video of what is weather Let's take a walk through the weather. Put on your hats and coats! Clouds Cloud Types Clouds - Dan's Wild Weather Page What to Wear? What to Wear? What to Drink? Weather Patterns and Climatic Regions ...

Ms. Bullough

2010-06-24

43

Weather  

NSDL National Science Digital Library

This is a first grade weather unit. SEASONS Fall Winter Build a Snowman Spring Summer What things determine and effect the weather? Cloud Precipitation Sunshine Temperature Visibility Wind Direction Wind Force WEATHER VIDEOS Tornado Hurricane Hail Lightning FUN AND GAMES Dress the Bear for the Weather The Great Weather Race Game Weather coloring books for kids ...

Ms. Stearns

2008-10-25

44

Weather  

NSDL National Science Digital Library

Learn all about the aspects of weather that effect us every day. Click here to see a weather forecast for anywhere in the world World Wide Weather Watch See what happens to weather when you change conditions at your house Weather Maker Weather Games ...

Mrs. Hyde

2007-02-08

45

State of the Atmosphere: Interpreting Weather Observations  

NSDL National Science Digital Library

The purpose of this lesson is to let students analyze atmospheric radiosonde data from a balloon launched at NASA Langley Research Center by teachers attending a workshop. Other resources are included to assist in interpreting the observations. Students are asked to explain in paragraph format their interpretation of the atmospheric conditions depicted by the data and the graph produced using the data.

LaFrance, Kim

2010-08-23

46

Characteristics of Operational Space Weather Forecasting: Observations and Models  

NASA Astrophysics Data System (ADS)

In contrast to research observations, models and ground support systems, operational systems are characterized by real-time data streams and run schedules, with redundant backup systems for most elements of the system. We review the characteristics of operational space weather forecasting, concentrating on the key aspects of ground- and space-based observations that feed models of the coupled Sun-Earth system at the NOAA/Space Weather Prediction Center (SWPC). Building on the infrastructure of the National Weather Service, SWPC is working toward a fully operational system based on the GOES weather satellite system (constant real-time operation with back-up satellites), the newly launched DSCOVR satellite at L1 (constant real-time data network with AFSCN backup), and operational models of the heliosphere, magnetosphere, and ionosphere/thermosphere/mesophere systems run on the Weather and Climate Operational Super-computing System (WCOSS), one of the worlds largest and fastest operational computer systems that will be upgraded to a dual 2.5 Pflop system in 2016. We review plans for further operational space weather observing platforms being developed in the context of the Space Weather Operations Research and Mitigation (SWORM) task force in the Office of Science and Technology Policy (OSTP) at the White House. We also review the current operational model developments at SWPC, concentrating on the differences between the research codes and the modified real-time versions that must run with zero fault tolerance on the WCOSS systems. Understanding the characteristics and needs of the operational forecasting community is key to producing research into the coupled Sun-Earth system with maximal societal benefit.

Berger, Thomas; Viereck, Rodney; Singer, Howard; Onsager, Terry; Biesecker, Doug; Rutledge, Robert; Hill, Steven; Akmaev, Rashid; Milward, George; Fuller-Rowell, Tim

2015-04-01

47

Weather  

NSDL National Science Digital Library

Have you ever wondered how the weather man, or meteorolgist, on TV knows what to say about tomorrow\\'s weather? It\\'s because they have certain tools that they use that help them predict what the weather will be. Throughout this school year you are going to be making tools and predicting weather just like a meterorologist! Task You are going to be weather forcasters! You are going to record and track weather patterns throughout the year. You will also use weather tools to make predictions about the weather like real weather forecasters! The Process 1. First we need to learn a little bit about weather so ...

Ms. Williams

2005-10-25

48

Use of meteorological satellite observations in weather modification programs  

NASA Technical Reports Server (NTRS)

The potential value of weather satellite data in field operations of weather modification is appraised. It was found that satellites could play a useful role in operational weather modification projects, particularly in the recognition of treatment opportunities. Satellite cloud photographs and infrared observations appear promising in the identification of treatment opportunities in seeding orographic cloud systems for increased snowpack, in seeding convective clouds for increased rainfall, in identifying hail threats, and in tracking and observing hurricanes as an aid to timing and location of seeding treatments. It was concluded that the potential value of satellite data in the treatment and evaluation phases of operational projects is not as great as in the recognition of treatment opportunity.

Dennis, A. S.; Smith, P. L., Jr.; Biswas, K. R.

1973-01-01

49

Surface chemistry associated with the cooling and subaerial weathering of recent basalt flows  

USGS Publications Warehouse

The surface chemistry of fresh and weathered historical basalt flows was characterized using surface-sensitive X-ray photoelectron spectroscopy (XPS). Surfaces of unweathered 1987-1990 flows from the Kilauea Volcano, Hawaii, exhibited variable enrichment in Al, Mg, Ca, and F due to the formation of refractory fluoride compounds and pronounced depletion in Si and Fe from the volatilization of SiF4 and FeF3 during cooling. These reactions, as predicted from shifts in thermodynamic equilibrium with temperature, are induced by diffusion of HF from the flow interiors to the cooling surface. The lack of Si loss and solid fluoride formation for recent basalts from the Krafla Volcano, Iceland, suggest HF degassing at higher temperatures. Subsequent short-term subaerial weathering reactions are strongly influenced by the initial surface composition of the flow and therefore its cooling history. Successive samples collected from the 1987 Kilauea flow demonstrated that the fluoridated flow surfaces leached to a predominantly SiO2 composition by natural weathering within one year. These chemically depleted surfaces were also observed on Hawaiian basalt flows dating back to 1801 AD. Solubility and kinetic models, based on thermodynamic and kinetic data for crystalline AlF3, MgF2, and CaF2, support observed elemental depletion rates due to chemical weathering. Additional loss of alkalis from the Hawaiian basalt occurs from incongruent dissolution of the basalt glass substrate during weathering. ?? 1992.

White, A.F.; Hochella, M.F., Jr.

1992-01-01

50

Weather Observation and Hail Suppression system in Slovenia  

Microsoft Academic Search

A computer supported system for Weather Observation and Hail Suppression at Lisca (Slovenia, Yugoslavia) is presented. The described system is of an operational type, where the hail prevention is based on launching anti-hail rockets. The system consists of a C-band meteorological radar, computers, a grid of rocket launchers and a communication subsystem between the radar computer center and the launchers,

Z. Lemut

1989-01-01

51

Observed Weather Satellite Thermal IR Responses Prior to Earthquakes  

Microsoft Academic Search

A number of observers claim to have seen thermal anomalies prior to earthquakes, but subsequent analysis by others have failed to produce similar findings. It was the purpose of this study to determine if thermal anomalies could be found in association with known earthquakes by systematically co-registering weather satellite images at the sub-pixel level and then determining if statistically significant

N. A. Bryant; A. L. Zobrist; L. L. Logan; F. Freund; S. Nishenko

2002-01-01

52

Weathering  

NSDL National Science Digital Library

This course handout covers the processes and effects of weathering. The purpose of this handout is to contrast weathering and erosion, contrast and discuss chemical and mechanical weathering, list the products resulting from the chemical weathering of igneous rocks, and list and discuss the factors that influence the type and rate of rock weathering. Many photographs accompany this summary which depict weathered landscapes. Links are provided to the online Physical Geology resources at Georgia Perimeter College.

Pamela Gore

1995-08-29

53

Weather observations on Whistler Mountain during five storms  

NASA Astrophysics Data System (ADS)

A greater understanding of precipitation formation processes over complex terrain near the west coast of British Colombia will contribute to many relevant applications, such as climate studies, local hydrology, transportation, and winter sport competition. The phase of precipitation is difficult to determine because of the warm and moist weather conditions experienced during the wintertime in coastal mountain ranges. The goal of this study is to investigate the wide range of meteorological conditions that generated precipitation on Whistler Mountain from 4-12 March 2010 during the SNOW-V10 field campaign. During this time period, five different storms were documented in detail and were associated with noticeably different meteorological conditions in the vicinity of Whistler Mountain. New measurement techniques, along with the SNOW-V10 instrumentation, were used to obtain in situ observations during precipitation events along the Whistler mountainside. The results demonstrate a high variability of weather conditions ranging from the synoptic-scale to the macro-scale. These weather events were associated with a variation of precipitation along the mountainside, such as events associated with snow, snow pellets, and rain. Only two events associated with a rain-snow transition along the mountainside were observed, even though above-freezing temperatures along the mountainside were recorded 90 % of the time. On a smaller scale, these events were also associated with a high variability of snowflake types that were observed simultaneously near the top of Whistler Mountain. Overall, these detailed observations demonstrate the importance of understanding small-scale processes to improve observational techniques, short-term weather prediction, and longer-term climate projections over mountainous regions.

Thériault, Julie M.; Rasmussen, Kristen L.; Fisico, Teresa; Stewart, Ronald E.; Joe, Paul; Gultepe, Ismail; Clément, Marilys; Isaac, George A.

2014-01-01

54

Infrared spectroscopy of weathering products in a terrestrial glacial environment: Implications for cold weathering on planetary surfaces  

NASA Astrophysics Data System (ADS)

Geologic features on Mars show evidence of modification by water and water ice. Past obliquity variations are hypothesized to have allowed the formation and stability of ground ice near the equator, possibly promoting the accumulation of glaciers. Massive ice deposits, including probable glacial and periglacial features have also been observed in the east Hellas Basin and Deuteronilus Mensae regions, located at the midlatitudes of Mars. These features indicate present-day, near-surface ice has been in contact with geologic materials, creating an environment in which cold weathering processes could have been occurring, and might still be at work. Weathering processes in cold terrestrial environments are not well understood, and processes acting on subglacial and englacial sediments and rocks are not well characterized due to the remote location of many glaciers and the difficulty of collecting samples. The types of weathering products and energy sources produced in a glacial environment will drive the overall energy budget for any microbial communities present. The subglacial energy budget for microbes thus has implications in the search for life on other planets, making glacial and periglacial terrains excellent sites for future exploration. However, planetary ice deposits are difficult to study due to their sensitive nature and are thus limited to observation from orbit at present. It is therefore a key concern to better understand the types materials and alteration products that can be observed and constrained from orbital data. In this study, we characterize the types of weathering products present in a glacial system using ground-truthed remote sensing techniques. Robertson Glacier, Alberta, Canada (115°20'W, 50°44'N) provides an excellent testbed for this technique as it is accessible, and its recent and continuing retreat allows fresh subglacial and englacial sediments to be sampled. Samples of bedrock and glacially altered rock and sediments were collected from Robertson Glacier. Infrared laboratory spectra of these samples were collected and used to determine the composition and abundance of minerals in rock and sediment samples, with a primary focus on differentiating weathering products. These spectra were then correlated to multispectral images taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite instrument. Initial results from both laboratory and ASTER data indicate the presence of weathering products. Laboratory spectra of field samples are promising in that major bedrock mineral assemblages and a variety of alteration products can be identified. However, more mineralogical work is required to refine the types of weathering products present in the system.

Rutledge, A. M.; Christensen, P. R.; Havig, J. R.

2011-12-01

55

Two cases of severe weather in Catalonia (Spain): an observational study  

Microsoft Academic Search

Surface observations, satellite and radar imagery and cloud-to-ground lightning data are used in an observational study of two cases that produced severe weather in Catalonia (Spain). The first one occurred on 24 August 1993; a squall line crossed Catalonia from west to east producing heavy rain with rates of up to 100 mm h[minus sign]1 and hail of 7 cm

Clemente Ramis; Joan Arús; José Manuel López; Antoni M. Mestres

1997-01-01

56

Mobile vehicle road and weather observation quality check methods  

NASA Astrophysics Data System (ADS)

Today State Departments of Transportation rely more and more on road weather data to make maintenance decisions. Inaccurate data can result in wrong treatment applications or inadequate staffing levels to maintain the roadway at the desired level of service. Previous methods of road condition data reporting have been limited to static in situ sensor stations. These road weather information systems (RWIS) provide varied data about precipitation, winds, temperature, and more, but their siting does not always provide an accurate representation of weather and road conditions along the roadway. The use of mobile data collection from vehicles travelling the highway corridors may assist in the locations where RWIS sitings are sparse or non-existent. The United States Department of Transporation's "Connected Vehicle" (formally IntelliDrive) research project is designed to create a fully connected transportation system providing road and weather data collection from an extensive array of vehicles. While the implementation of Connected Vehicle is in the future, some of the theories and technologies are already in place today. Several states, as a part of the Pooled Fund Study Maintenance Decision Support System (MDSS), have equipped their winter maintenance vehicles with Mobile Data Collection Automated / Vehicle Location (MDC/AVL) systems. In addition, since 1996, automobiles sold in the United States are required to be equipped with an Onboard Diagnostic Version 2 (OBDII) port that streams live data from sensors located in and around the vehicle. While these sensors were designed for vehicle diagnostics, some of the data can be used to determine weather characteristics around the vehicle. The OBDII data can be collected by a smartphone and sent to a server in real time to be processed. These mobile systems may fill the information gap along the roads that stationary environmental sensor stations are not able to collect. Particular concern and care needs to be focused on data quality and accuracy, requiring the development of quality checks for mobile data collection. Using OBDII-equipped automobiles and mobile collection methods, we can begin to address issues of data quality by understanding, characterizing, and demonstrating the quality of mobile system observations from operational and research environments. Several forms of quality checking can be used, including range checks, Barnes spatial checks, comparing vehicle data to road weather models, and applying Clarus quality check methodologies and algorithms to mobile observations. Development of these quality checks can lead to the future integration of mobile data into the Clarus system, data implementation for improved forecasting, maintenance decision support, and traveler safety. This paper will discuss the benefits and challenges in mobile data collection, along with how the development and implementation of a system of quality checks will improve the quality and accuracy of mobile data collection.

Koller, Daniel Raymond

57

Observational and modelling studies of Australian severe weather  

NASA Astrophysics Data System (ADS)

The forecastability of severe weather conditions over sub-tropical Australia are tested with a mesoscale model capable of running at high resolutions over a region of interest anywhere in the world. Improved forecast output, for example, of precipitation, wind speed/direction and humidity which are required to indicate severe weather conditions are dependent on model improvements and the following areas are addressed: (1)data; (2)theory; (3)model; and, (4)computing. The initial condition uncertainty inherent in the data which is used in the analysis to initialise numerical weather prediction (NWP) models is addressed through two ensemble forecasting studies, one on rainfall from a mesoscale system and the other on the central low position, wind and rainfall distribution of an explosive east coast low. Also, relating to data, some major mesoscale phenomena are described in the form of New South Wales coastal ridging which helps produce severe weather in this area and which needs to be captured by a mesoscale NWP model in order that improved predictions can be made. In terms of theory the major focus is on the ensemble methodology and on the use of improved precipitation parameterisations, namely, those of Fritsch-Chappell and Kain-Fritsch. The mesoscale model development is extended through the use of increased resolution studies, for example, by showing statistically significant greater than operational skill in predicting details of wind, relative humidity and temperature patterns both near the surface and above the boundary layer in relation to the Sydney January 1994 bushfire weather; by including an option for a Lagrangian particle dispersion model; and by replacement of a previously inadequate representation of cumulus convection which was required to represent the effects of mesoscale downdrafts which are essential for the successful prediction of the squall-line over Sydney in Chapter 7. Mesoscale weather prediction is one of the so called `grand challenges' of computational science in that it requires large amounts of memory and very efficient use of high performance computers. In this thesis the computations ranged form multiprocessor shared memory main frames; high performance work stations; and, now state-of-the-art Pentium PCs. Each of these machines has its distinct requirements for optimisation. Much work has been dedicated in producing code that transfers easily between platforms.

Speer, Milton Samuel

1998-09-01

58

Weather  

NSDL National Science Digital Library

What are the different types of weather? In this project you will compare different types of weather by drawing pictures and making it into a flip book. First you will begin by learning about the different types of weather. Read about each topic. Then get together with your partner and draw a picture of each type of weather. 1. Thunder storm Thunder storm Thunder storm Kids 2. Lightning Lightning Lightning picture 3. Tornado Tornadoes Tornado Kids 4. ...

Miss Jennie

2009-10-22

59

A climatological link between slantwise instability and surface weather conditions  

NASA Astrophysics Data System (ADS)

Midlatitude weather phenomena including rainbands in fronts and cloud heads and the descending sting jets found in extreme windstorms have been attributed, in part, to the release of conditional symmetric instability (CSI). CSI is a slantwise parcel instability arising from the combination of inertial and gravitational instability in a baroclinic atmosphere; its release gives slantwise convection. However, to date, demonstration of the link between CSI and severe weather has been confined to a few case studies. Weather forecast models with domains big enough to encompass entire midlatitude storms do not have sufficient resolution to realistically resolve the release of CSI, and CSI release is not parameterized in these models. The consequences of this lack of representation of CSI release are currently unknown and motivate this study. We present a North Atlantic climatology of the energy available for slantwise convection due to CSI derived from the ERA-Interim re-analysis, and compare it with an equivalent climatology of CAPE (the energy available for upright convection due to conditional instability). The annual cycle of land and sea surface temperatures are shown to strongly modulate these instabilities. The statistical relationship between these instabilities and surface weather conditions are presented.

Glinton, M. R.; Gray, S. L.; Chagnon, J. M.; Morcrette, C. J.

2012-04-01

60

Does mineral surface area affect chemical weathering rates?  

NASA Astrophysics Data System (ADS)

Iceland is a basaltic volcanic island representative of the high relief, volcanic and tectonic active islands that contribute over 45% of river suspended material to the oceans worldwide (Milliman and Syvitski, 1992). These islands have enormous mechanical and chemical weathering rates due to the combined effects of high relief, high runoff, the presence of glaciers and easily weathered volcanic rocks, and a lack of sedimentary traps. In total, Iceland delivers 0.7% of the worldwide river suspended matter flux to the ocean, which is approximately one fourth that of Africa (Tómasson, 1990). River suspended matter from volcanic islands is highly reactive in seawater and might play an important role in the global carbon cycle (Gislason et al., 2006). Thus it is important to define and understand the mechanical and chemical weathering rates of these islands. Experimental dissolution experiments performed in the laboratory suggest that chemical weathering rates should be proportional to rock-water interfacial surface area. This hypothesis is tested in the present study through a study of the chemical composition of suspended material collected from rivers located in Northeast Iceland. These rivers were selected for this study because their catchments essentially monolithic, consisting of uniform compositioned and aged basalts. Gaillardet (1999) described weathering intensities of the worlds river systems to be from 1 (low weathering intensity) to 25 (high weathering intensity). These indexes were calculated to be from 1.8 to 3.2 in rivers in NE-Iceland (Eiriksdottir et al., 2008). The surface area of sediments is inversely proportional to particle size; smaller particles have larger specific surface areas. As a result, smaller particles should weather faster. This trend is confirmed by the measured compositions of analyzed suspended material. The concentration of insoluble elements (Zr, Fe, Cu, Ni, Y) is found to increase in the suspended material, whereas the concentration of soluble elements (Na, Ca, Ba, V) decrease with decreasing particle size in samples collected from various catchments. References. Eiriksdottir E.S., Louvat P., Gislason S.R., Óskarsson N., Hardardóttir J., 2008. Temporal variation of chemical and mechanical weathering in NE Iceland: Evaluation of a steady-state model of erosion. EPSL 272, 78-88 Gaillardet, J., Dupré, B., Allegre, C.J., Négrel, P., 1999b. Geochemistry of large river suspended sediments: silicate weathering or recycling tracer? Geochim. Cosmochim. Acta 63, 4037-4051. Gislason, S.R., Oelkers, E.H., Snorrason, Á., 2006. Role of river-suspended material in the global carbon cycle. Geology 34, 49-52. Milliman, J.D., Syvitski, J.P.M., 1992. Geomorphic/tectonic control of sediment discharge to the ocean: the importance of small mountainous rivers. J. Geol. 100, 525-544. Tómasson, H., 1990. Suspended material in Icelandic rivers. In: Guttormur, S. (Ed.), Vatnid og Landid. Orkustofnun, Reykjavik, pp. 169-174.

Salome Eiriksdottir, Eydis; Reynir Gislason, Sigurdur; Oelkers, Eric H.

2010-05-01

61

Surface Landing Site Weather Analysis for NASA's Constellation Program  

NASA Technical Reports Server (NTRS)

Weather information is an important asset for NASA's Constellation Program in developing the next generation space transportation system to fly to the International Space Station, the Moon and, eventually, to Mars. Weather conditions can affect vehicle safety and performance during multiple mission phases ranging from pre-launch ground processing of the Ares vehicles to landing and recovery operations, including all potential abort scenarios. Meteorological analysis is art important contributor, not only to the development and verification of system design requirements but also to mission planning and active ground operations. Of particular interest are the surface weather conditions at both nominal and abort landing sites for the manned Orion capsule. Weather parameters such as wind, rain, and fog all play critical roles in the safe landing of the vehicle and subsequent crew and vehicle recovery. The Marshall Space Flight Center (MSFC) Natural Environments Branch has been tasked by the Constellation Program with defining the natural environments at potential landing zones. This paper wiI1 describe the methodology used for data collection and quality control, detail the types of analyses performed, and provide a sample of the results that cab be obtained.

Altino, Karen M.; Burns, K. L.

2008-01-01

62

Surface ozone concentration trends and its relationship with weather types in Spain (2001-2010)  

NASA Astrophysics Data System (ADS)

This paper assesses the temporal variations of surface ozone concentrations during the period 2001-2010 in 3 regions of Spain with different geographical and socioeconomic features (northern coastland, central inland and northeast inland), as well as its link with atmospheric circulation. Specifically, daily surface atmospheric patterns over the aforementioned regions are characterized using NCEP/NCAR reanalysis data and an objective classification scheme in order to study the relationship between synoptic weather types and daily ozone levels. The results show that tropospheric ozone concentration has a tendency towards an increase during the study period, both during daytime and nighttime. Moreover, in general, this upward trend is seen throughout all of the seasons. The observed trends are in line with a reported decrease of NOX emissions and increase in surface solar radiation during the 2000s in Spain. On the other hand, interestingly, median concentrations were statistically significantly lower in days with anticyclonic weather conditions than in the rest of meteorological situations, while days with a directional weather type showed higher median levels of ozone concentration, with maximum values in days with northern and eastern component. Due to the detrimental effect that ozone has on human health, the relationship between synoptic weather patterns and daily ozone levels shown in this work could potentially be used for implementing pollution level alert protocols depending on forecast weather types.

Santurtún, Ana; González-Hidalgo, José Carlos; Sanchez-Lorenzo, Arturo; Zarrabeitia, María Teresa

2015-01-01

63

Preserving the Nation's Weather and Climate History People have observed and recorded the weather for thousands of years. Native American petroglyphs often depict rain,  

E-print Network

Preserving the Nation's Weather and Climate History People have observed and recorded the weather, colonists from Europe began recording journal entries about the weather and natural environment they observed. By the late 1700s, accurate weather instruments, such as thermometers, were available

64

Modeling apple surface temperature dynamics based on weather data.  

PubMed

The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST) dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed) was recorded for seven hours between 11:00-18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of "Fuji" apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management. PMID:25350507

Li, Lei; Peters, Troy; Zhang, Qin; Zhang, Jingjin; Huang, Danfeng

2014-01-01

65

Modeling Apple Surface Temperature Dynamics Based on Weather Data  

PubMed Central

The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST) dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed) was recorded for seven hours between 11:00–18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of “Fuji” apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management. PMID:25350507

Li, Lei; Peters, Troy; Zhang, Qin; Zhang, Jingjin; Huang, Danfeng

2014-01-01

66

Two cases of severe weather in Catalonia (Spain): an observational study  

NASA Astrophysics Data System (ADS)

Surface observations, satellite and radar imagery and cloud-to-ground lightning data are used in an observational study of two cases that produced severe weather in Catalonia (Spain). The first one occurred on 24 August 1993; a squall line crossed Catalonia from west to east producing heavy rain with rates of up to 100 mm h[minus sign]1 and hail of 7 cm diameter. The observational information provided is a good tool for monitoring the event and issuing a reasonable nowcast. The second case, which occurred on 31 August 1994, was associated with the development of a tornado (F1 in the Fujita scale) as well as hail of up to 5 cm diameter. In this case the convection was almost stationary and no clear signatures of severe weather can be identified from available satellite and radar imagery.

Ramis, Clemente; Arús, Joan; López, José Manuel; Mestres, Antoni M.

1997-09-01

67

Widespread Weathered Glass on the Surface of Mars  

NASA Technical Reports Server (NTRS)

Low albedo sediments cover >10(exp 7) sq km in the northern lowlands of Mars, but the composition and origin of these widespread deposits have remained ambiguous despite many previous investigations. Here we use near-infrared spectra acquired by the Mars Express OMEGA (Observatoire pour la Mineralogie, l'Eau, les Glaces, et l'Activite') imaging spectrometer to show that these sediments exhibit spectral characteristics that are consistent with both high abundances of iron-bearing glass and silica-enriched leached rinds on glass. This interpretation is supported by observations of low-albedo soil grains with possible rinds at the Phoenix Mars Lander landing site in the northern lowlands. By comparison with the extensive glass-rich dune fields and sand sheets of Iceland, we propose an explosive volcanic origin for these glass-rich sediments. We also propose that the glassy remnant rinds on the sediments are the result of post-depositional alteration, as these rinds are commonly formed in arid terrestrial volcanic environments during water-limited, moderately acidic leaching. These weathered, glass-rich deposits in the northern lowlands are also colocated with the strongest concentrations of a major global compositional surface type previously identified in mid-infrared spectra, suggesting that they may be representative of global processes. Our results provide potential confirmation of models suggesting that explosive volcanism has been widespread on Mars, and also raise the possibilities that glass-rich volcaniclastics are a major source of eolian sand on Mars and that widespread surficial aqueous alteration has occurred under Amazonian climatic conditions.

Horgan, Briony; Bell, James F., III

2012-01-01

68

Surface Meteorological Observation System (SMOS) Handbook  

SciTech Connect

The Surface Meteorological Observation System (SMOS) mostly uses conventional in situ sensors to obtain 1-minute, 30-minute, and 1440-minute (daily) averages of surface wind speed, wind direction, air temperature, relative humidity (RH), barometric pressure, and precipitation at the Central Facility and many of the extended facilities of the Southern Great Plains (SGP) climate research site. The SMOSs are not calibrated as systems. The sensors and the data logger (which includes the analog-to-digital converter, or A/D) are calibrated separately. All systems are installed using components that have a current calibration. SMOSs have not been installed at extended facilities located within about 10 km of existing surface meteorological stations, such as those of the Oklahoma Mesonet. The Surface Meteorological Observation Systems are used to create climatology for each particular location, and to verify the output of numerical weather forecast and other model output. They are also used to “ground-truth” other remote sensing equipment.

Ritsche, MT

2008-03-01

69

Potential Impacts of Stratospheric Observations on Weather Forecasts  

NASA Astrophysics Data System (ADS)

This study examines the potential impact of novel stratospheric measurements on tropospheric weather forecasts. We focus on the upper stratosphere, where routine measurements of temperature and winds are sparse, and where there is potential to expand the current observing system using measurements from the ARISE (Atmospheric Dynamics Research Infrastructure in Europe) network. We consider 30 day forecasts initiated just before Sudden Stratospheric Warmings (SSWs). Previous studies have shown a small but significant impact on tropospheric forecast skill, for NWP forecasts after 5 days, when stratospheric initial conditions are severely degraded, and a similar increase in forecast skill when the stratospheric state is damped towards observed conditions. Using a version of the second technique we are able to reproduce previous results, which show around a 5% increase in tropospheric forecast skill when the stratosphere is damped towards its observed state. We then use the same technique to compare the quantitative impact of damping the stratospheric state towards observations in the lower and upper stratosphere (with a boundary at 40km), and for observations in the European sector only.

Lee, Christopher; Charlton-Perez, Andrew; Harrison, R. Giles

2014-05-01

70

Weathering  

NSDL National Science Digital Library

This interactive Flash resource provides information regarding physical and chemical weathering at an introductory physical geology or Earth science level. It includes animations, diagrams, and supplementary information and is suitable for high school or undergraduate students.

Smoothstone

71

WHAT TO DO DURING SEVERE WEATHER WHILE ON CAMPUS If you observe a tornado/severe weather, you hear tornado sirens sound or receive a  

E-print Network

WHAT TO DO DURING SEVERE WEATHER WHILE ON CAMPUS If you observe a tornado/severe weather, you hear Clear Emergency Notification Text: OU Alert: The weather danger has passed. You may resume normal activity. New this season is our 2014 Severe Weather Procedure for Particularly Dangerous Storm (PDS

Oklahoma, University of

72

Tropical Ocean Surface Energy Balance Variability: Linking Weather to Climate Scales  

NASA Technical Reports Server (NTRS)

Radiative and turbulent surface exchanges of heat and moisture across the atmosphere-ocean interface are fundamental components of the Earth s energy and water balance. Characterizing the spatiotemporal variability of these exchanges of heat and moisture is critical to understanding the global water and energy cycle variations, quantifying atmosphere-ocean feedbacks, and improving model predictability. These fluxes are integral components to tropical ocean-atmosphere variability; they can drive ocean mixed layer variations and modify the atmospheric boundary layer properties including moist static stability, thereby influencing larger-scale tropical dynamics. Non-parametric cluster-based classification of atmospheric and ocean surface properties has shown an ability to identify coherent weather regimes, each typically associated with similar properties and processes. Using satellite-based observational radiative and turbulent energy flux products, this study investigates the relationship between these weather states and surface energy processes within the context of tropical climate variability. Investigations of surface energy variations accompanying intraseasonal and interannual tropical variability often use composite-based analyses of the mean quantities of interest. Here, a similar compositing technique is employed, but the focus is on the distribution of the heat and moisture fluxes within their weather regimes. Are the observed changes in surface energy components dominated by changes in the frequency of the weather regimes or through changes in the associated fluxes within those regimes? It is this question that the presented work intends to address. The distribution of the surface heat and moisture fluxes is evaluated for both normal and non-normal states. By examining both phases of the climatic oscillations, the symmetry of energy and water cycle responses are considered.

Roberts, J. Brent; Clayson, Carol Anne

2013-01-01

73

How does stratospheric variability affect surface weather and climate?  

NASA Astrophysics Data System (ADS)

Changes to the stratosphere, due to both natural variability and ozone depletion, have substantial effects on surface weather and climate, especially at middle to high latitudes. Despite clear evidence of these impacts, the primary dynamics of this phenomenon are not yet well understood. Here we show that the stratospheric meridional circulation forces the column of air above the Arctic downwards into the troposphere, acting like a mechanical plunger that controls the day-to-day thickness of the troposphere. This vertical motion directly affects temperatures and the strength of jets in the mid- to upper troposphere. Raising and lowering of the Arctic tropopause layer leads to stretching and compression of the tropospheric column and a north-south dipole in surface pressure similar to the Northern Annular Mode.

Baldwin, Mark; Birner, Thomas

2013-04-01

74

WEATHER OBSERVATIONS - SUMMARY OF THE DAY - FIRST ORDER  

EPA Science Inventory

The National Climatic Data Center makes available daily weather data for approximately 300 currently active National Weather Service stations, with a lag time (after end of data month) of about 8-10 weeks. Coverage includes the contiguous United States, Caribbean Islands, Pacific...

75

Aviation & Space Weather Policy Research: Integrating Space Weather Observations & Forecasts into Operations  

NASA Astrophysics Data System (ADS)

The American Meteorological Society and SolarMetrics Limited are conducting a policy research project leading to recommendations that will increase the safety, reliability, and efficiency of the nation's airline operations through more effective use of space weather forecasts and information. This study, which is funded by a 3-year National Science Foundation grant, also has the support of the Federal Aviation Administration and the Joint Planning and Development Office (JPDO) who is planning the Next Generation Air Transportation System. A major component involves interviewing and bringing together key people in the aviation industry who deal with space weather information. This research also examines public and industrial strategies and plans to respond to space weather information. The focus is to examine policy issues in implementing effective application of space weather services to the management of the nation's aviation system. The results from this project will provide government and industry leaders with additional tools and information to make effective decisions with respect to investments in space weather research and services. While space weather can impact the entire aviation industry, and this project will address national and international issues, the primary focus will be on developing a U.S. perspective for the airlines.

Fisher, G.; Jones, B.

2006-12-01

76

Development of a Graphical User Interface to Visualize Surface Observations  

SciTech Connect

Thousands of worldwide observing stations provide meteorological information near the earth's surface as often as once each hour. This surface data may be plotted on geographical maps to provide the meteorologist useful information regarding weather patterns for a region of interest. This report describes the components and applications of a graphical user interface which have been developed to visualize surface observations at any global location and time of interest.

Buckley, R.L.

1998-07-13

77

Weather  

NSDL National Science Digital Library

In the project you will learn about thunderstorms and tornadoes and play a weather matching game. What exactly are thunderstorms and tornadoes? Use your T- chart to explain some facts about a thunderstorm and a tornado as we review each. T-Chart Begin by reviewing what a thunderstorm is and how they form. Thunderstorm information What is a thunderstorm? What are thunderstorms most likely to occur? What causes thunder? Next review what a tornado ...

Ms. Caitlin

2009-10-21

78

Weather Radars and Lidar for Observing the Atmosphere  

NASA Astrophysics Data System (ADS)

The Earth Observing Laboratory (EOL) at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado develops and deploys state-of-the-art ground-based radar, airborne radar and lidar instruments to advance scientific understanding of the earth system. The ground-based radar (S-Pol) is equipped with dual-wavelength capability (S-band and Ka-band). S-Pol is the only transportable radar in the world. In order to capture faster moving weather events such as tornadoes and record observations of clouds over rugged mountainous terrain and ocean, an airborne radar (ELDORA) is used. It is the only airborne Doppler meteorological radar that is able to detect motions in the clear air. The EOL is in the process of building the first phase of a three phase dual wavelength W/Ka-band airborne cloud radar to be called the HIAPER Cloud Radar (HCR). This phase is a pod based W-band radar system with scanning capability. The second phase will add pulse compression and polarimetric capability to the W-band system, while the third phase will add complementary Ka-band radar. The pod-based radar is primarily designed to fly on the Gulfstream V (GV) and C-130 aircraft. The envisioned capability of a millimeter wave radar system on GV is enhanced by coordination with microwave radiometer, in situ probes, and especially by the NCAR GV High-Spectral Resolution Lidar (HSRL) which is also under construction. The presentation will describe the capabilities of current instruments and also planned instrumentation development.

(Vivek) Vivekanandan, J.

2010-05-01

79

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science  

NASA Technical Reports Server (NTRS)

We often look "through a glass, darkly" at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers are radiation crusts on cometary nuclei and iogenic components of sulfate hydrate deposits on the trailing hemisphere of Europa. Weathering processes include plasma ion implantation into surfaces, sputtering by charged particles and solar ultraviolet photons, photolytic chemistry driven by UV irradiation, and radiolytic chemistry evolving from products of charged particle irradiation. Regolith structure from impacts, and underlying deeper structures from internal evolution, affects efficacy of certain surface interactions, e.g. sputtering as affected by porosity and surface irradiation dosage as partly attenuated by local topographic shielding. These processes should be regarded for mission science planning as potentially enabling, e.g. since direct surface sputtering, and resultant surface-bound exospheres, can provide in-situ samples of surface composition to ion and neutral mass spectrometers on orbital spacecraft. Sample return for highest sensitivity compOSitional and structural analyses at Earth will usually be precluded by limited range of surface sampling, long times for return, and high cost. Targeted advancements in instrument technology would be more cost efficient for local remote and in-situ sample analysis. More realistic laboratory simulations, e.g. for bulk samples, are needed to interpret mission science observations of weathered surfaces. Space environment effects on mission spacecraft and science operations must also be specified and mitigated from the hourly to monthly changes in space weather and from longer term (e.g., solar cycle) evolution of space climate. Capable instrumentation on planetary missions can and should be planned to contribute to knowledge of interplanetary space environments. Evolving data system technologies such as virtual observatories should be explored for more interdisciplinary application to the science of planetary surface, atmospheric, magnetospheric, and interplanetary interactions.

Cooper, John F.

2011-01-01

80

Formation of the Surface Space Charge Layer in Fair Weather  

NASA Astrophysics Data System (ADS)

It is widely known that the positive space charge, caused by electrode effect action, is obtained near surface in fair weather. Space charge density depends on the different local features: meteorological conditions, aerosol particles concentration, convective transfer of the surface layer. Namely space charge determines the local variations of electric field. Space charge could be negative in condition of strong ionization rate in thin air layer near surface. The electrodynamic model, consisting of transfer equations of light ions and nucleuses, generated by interactions between lights ions and aerosol particles, and Poisson equation. The turbulent transfer members, electric field near the surface, the mobility of positive and negative ions, recombination coefficient, ionization rate, the number of elementary charges on the nuclei were took into account in the model equations. The time-space variations of positive and negative small and heavy ions, electric field, electrical conductivity, current density and space charge, depending on aerosol particles concentrations, turbulence and convective transfer ionization rate, aerosol particles size and number of charged on the particles are calculated. The mechanisms of turbulent and convection-turbulent surface layer electrodynamic structure forming in dependence of single and multi-charged aerosol particles for different physical and meteorological conditions are investigated. Increasing of turbulent mixing intensity leads to increasing of character electrode layer thickness, decreasing of space charge density value, decreasing of electric current conductivity value. The electrode effect of the whole layer remains constant. Increasing of aerosol particles concentration leads to decreasing of electrode effect within the whole electrode layer and increasing of electric field values, decreasing of space charge density values and current conductivity density. It was received that increasing of the aerosol particles concentration under weak turbulent mixing leads to increasing of the negative space charge density and its displacement to the surface level. Under severe contamination condition the electrodynamic structure of surface layer is primarily determined by negative space charge, generated by nucleuses. It was received that in case of small aerosol particles the surface layer electrodynamic structure is basically established by single- and double-charged particles. Single-charged and double-charged as triply-charged, fourfold-charged and fivefold-charged aerosol particles primarily affect on electrodynamic structure of the surface layer in case of increasing of aerosol particles size. The local variations of the electric field in different conditions were studied. Theoretical results are in a good agreement with experimental facts.

Redin, Alexander; Kupovykh, Gennady; Boldyreff, Anton

2014-05-01

81

Observations and Impact Assessments of Extreme Space Weather Events  

NASA Astrophysics Data System (ADS)

"Space weather" refers to conditions on the Sun, in the solar wind, and in Earth`s magnetosphere, ionosphere, and thermosphere. Activity on the Sun such as solar flares and coronal mass ejections can lead to high levels of radiation in space and can cause major magnetic storms at the Earth. Space radiation can come as energetic particles or as electromagnetic emissions. Adverse conditions in the near-Earth space environment can cause disruption of satellite operations, communications, navigation, and electric power distribution grids. This can lead to a variety of socioeconomic losses. Astronauts and airline passengers exposed to high levels of radiation are also at risk. Society`s vulnerability to space weather effects is an issue of increasing concern. We are dependent on technological systems that are becoming more susceptible to space weather disturbances. We also have a permanent human presence in space with the International Space Station and the President and NASA have expressed a desire to expand our human space activities with missions to the moon and Mars. This will make space weather of even greater concern in the future. In this talk I will describe many space weather effects and will describe some of the societal and economic impacts that extreme events have had.

Baker, D. N.

2007-05-01

82

Chitinophaga qingshengii sp. nov., isolated from weathered rock surface.  

PubMed

A novel mineral-weathering bacterium was isolated from weathered rock (potassic trachyte) surfaces collected from Nanjing (Jiangsu, PR China). Cells of strain JN246(T) were Gram-stain-negative, rod-shaped and non-motile. Strain JN246(T) was aerobic, catalase- and oxidase-positive, and grew optimally at 28 °C and pH 7.0. On the basis of 16S rRNA gene sequence analysis, strain JN246(T) belonged to the genus Chitinophaga and the closest phylogenetic relatives were Chitinophaga eiseniae YC6729(T) (98.5% 16S rRNA gene sequence similarity), Chitinophaga terrae KP01(T) (96.8%), and Chitinophaga jiangningensis JN53(T) (96.3?%). The major respiratory quinone was MK-7 and the major polyamine was homospermidine. The major fatty acids were iso-C15:0, C16:1?5c, C16:0 and iso-C17:0 3-OH. The polar lipid profile of strain JN246(T) consisted of phosphatidylethanolamine, unknown aminolipids and unknown lipids. The genomic DNA G+C content of strain JN246(T) was 48.8 mol%. Based on the low level of DNA-DNA relatedness of strain JN246(T) (ranging from 22.6% to 42.4%) to the type strains of other species of the genus Chitinophaga and unique phenotypic characteristics, strain JN246(T) represents a novel species of the genus Chitinophaga, for which the name Chitinophaga qingshengii sp. nov. is proposed. The type strain is JN246(T) (?=?CCTCC AB 2014201(T)?=?JCM 30026(T)). PMID:25342110

Cheng, Cheng; Wang, Qi; He, Lin-Yan; Huang, Zhi; Sheng, Xia-Fang

2015-01-01

83

Training Guide in Surface SAWRS Observations.  

ERIC Educational Resources Information Center

As a replacement of the 1949 primary training manual for supplementary aeronautical weather reports, instructions are presented in this Training Paper No. 5 for the purpose of guiding learners through their study of the Weather Service Observing Handbook (WSOH) No. 4. The content is divided into six chapters concerned with such topics as…

National Oceanic and Atmospheric Administration (DOC), Rockville, MD. National Weather Service.

84

Space Weather Monitoring for ISS Space Environments Engineering and Crew Auroral Observations  

NASA Technical Reports Server (NTRS)

Today s presentation describes how real time space weather data is used by the International Space Station (ISS) space environments team to obtain data on auroral charging of the ISS vehicle and support ISS crew efforts to obtain auroral images from orbit. Topics covered include: Floating Potential Measurement Unit (FPMU), . Auroral charging of ISS, . Real ]time space weather monitoring resources, . Examples of ISS auroral charging captured from space weather events, . ISS crew observations of aurora.

Minow, Joseph; Pettit, Donald R.; Hartman, William A.

2012-01-01

85

Data assimilation of dead fuel moisture observations from remote automated weather stations  

E-print Network

Fuel moisture has a major influence on the behavior of wildland fires and is an important underlying factor in fire risk assessment. We propose a method to assimilate dead fuel moisture content observations from remote automated weather stations (RAWS) into a time-lag fuel moisture model. RAWS are spatially sparse and a mechanism is needed to estimate fuel moisture content at locations potentially distant from observational stations. This is arranged using a trend surface model (TSM), which allows us to account for the effects of topography and atmospheric state on the spatial variability of fuel moisture content. At each location of interest, the TSM provides a pseudo-observation, which is assimilated via Kalman filtering. The method is tested with the time-lag fuel moisture model in the coupled weather-fire code WRF-SFIRE on 10-hr fuel moisture content observations from Colorado RAWS in 2013. We show using leave-one-out testing that the TSM compares favorably with inverse squared distance interpolation as u...

Vejmelka, Martin; Mandel, Jan

2014-01-01

86

Weather Information System  

NASA Technical Reports Server (NTRS)

WxLink is an aviation weather system based on advanced airborne sensors, precise positioning available from the satellite-based Global Positioning System, cockpit graphics and a low-cost datalink. It is a two-way system that uplinks weather information to the aircraft and downlinks automatic pilot reports of weather conditions aloft. Manufactured by ARNAV Systems, Inc., the original technology came from Langley Research Center's cockpit weather information system, CWIN (Cockpit Weather INformation). The system creates radar maps of storms, lightning and reports of surface observations, offering improved safety, better weather monitoring and substantial fuel savings.

1995-01-01

87

Experimental observations of the effects of bacteria on aluminosilicate weathering  

Microsoft Academic Search

Mineral dissolution experiments using batch cultures of soil and groundwater bacteria were monitored with solution chemistry and various microscopic techniques to determine the effects of these organisms on weathering reactions. Several strains of bacteria produced organic and inorganic acids and extracellular polymers in culture, increasing the release of cations from biotite (Si, Fe, Al) and plagioclase feldspar (Si, Al) by

W. W. Barker; S. A. Welch; S. Chu; J. F. Banfield

1998-01-01

88

MY NASA DATA: State of the Atmosphere - Interpreting Weather Observations  

NSDL National Science Digital Library

This lesson consists of three activities. Students will discover the effect of temperature and pressure on cloud formation, analyze weather balloon data, and interpret a graph created from the synthesis of data sets on temperature, relative humidity and dew point. This lesson uses student- and citizen science-friendly microsets of authentic NASA Earth system science data from the MY NASA DATA project. It includes related links.

89

Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroid Space Weathering Studies  

NASA Technical Reports Server (NTRS)

Understanding the composition of Mercury's crust is key to comprehending the formation of the planet. The regolith, derived from the crustal bedrock, has been altered via a set of space weathering processes. These processes are the same set of mechanisms that work to form Mercury's exosphere, and are moderated by the local space environment and the presence of an intrinsic planetary magnetic field. The alterations need to be understood in order to determine the initial crustal compositions. The complex interrelationships between Mercury's exospheric processes, the space environment, and surface composition are examined and reviewed. The processes are examined in the context of our understanding of these same processes on the lunar and asteroid regoliths. Keywords: Mercury (planet) Space weathering Surface processes Exosphere Surface composition Space environment 3

Dominque, Deborah L.; Chapman, Clark R.; Killen, Rosemary M.; Zurbuchen, Thomas H.; Gilbert, Jason A.; Sarantos, Menelaos; Benna, Mehdi; Slavin, James A.; Orlando, Thomas M.; Schriver, David; Sprague, Ann L.; Blewett, David T.; Gillis-Davis, Jeffrey J.; Feldman, William C.; Lawrence, David J.; Ho, George C.; Vilas, Faith; Pieters, Carle M.; McClintock, William E.; Helbert, Jorn

2011-01-01

90

Impact of various observing systems on weather analysis and forecast over the Indian region  

NASA Astrophysics Data System (ADS)

To investigate the potential impact of various types of data on weather forecast over the Indian region, a set of data-denial experiments spanning the entire month of July 2012 is executed using the Weather Research and Forecasting (WRF) model and its three-dimensional variational (3DVAR) data assimilation system. The experiments are designed to allow the assessment of mass versus wind observations and terrestrial versus space-based instruments, to evaluate the relative importance of the classes of conventional instrument such as radiosonde, and finally to investigate the role of individual spaceborne instruments. The moist total energy norm is used for validation and forecast skill assessment. The results show that the contribution of wind observations toward error reduction is larger than mass observations in the short range (48 h) forecast. Terrestrial-based observations generally contribute more than space-based observations except for the moisture fields, where the role of the space-based instruments becomes more prevalent. Only about 50% of individual instruments are found to be beneficial in this experiment configuration, with the most important role played by radiosondes. Thereafter, Meteosat Atmospheric Motion Vectors (AMVs) (only for short range forecast) and Special Sensor Microwave Imager (SSM/I) are second and third, followed by surface observations, Sounder for Probing Vertical Profiles of Humidity (SAPHIR) radiances and pilot observations. Results of the additional experiments of comparative performance of SSM/I total precipitable water (TPW), Microwave Humidity Sounder (MHS), and SAPHIR radiances indicate that SSM/I is the most important instrument followed by SAPHIR and MHS for improving the quality of the forecast over the Indian region. Further, the impact of single SAPHIR instrument (onboard Megha-Tropiques) is significantly larger compared to three MHS instruments (onboard NOAA-18/19 and MetOp-A).

Singh, Randhir; Ojha, Satya P.; Kishtawal, C. M.; Pal, P. K.

2014-09-01

91

Seasonal changes in Titan's weather and surface features  

NASA Astrophysics Data System (ADS)

Since Cassini's arrival at Saturn, the Titan's season has progressed from southern summer to just past the southern autumnal equinox (the equivalent of 12 January to 26 March), and accompanying changes in meteorology have been observed. Through 2004, large convective cloud systems were common over Titan's South Pole (e.g., Schaller et al., 2006); since 2005 such storms have been less common. Elongated streaks of clouds have been observed consistently at mid-southern latitudes, and became common at high northern latitudes in 2007. Only recently have clouds been detected at mid-northern latitudes. Changes have also been observed in surface features at high southern latitudes. A large dark area appeared between July 2004 and June 2005 (Turtle et al., 2009), and may have subsequently faded. Recent observations of Ontario Lacus suggest that its shoreline may have receded (e.g., Hayes et al., 2009). No changes have been observed to date in lakes and seas at high northern latitudes. Intriguingly, Cassini RADAR observations of Titan's South Pole reveal far fewer lakes than have been identified in the north (Stofan et al., 2007) and fewer than suggested by the number of dark features observed by ISS in this area (Turtle et al., 2009). This apparent discrepancy may indicate that not all of the dark south-polar features identified by ISS are filled with liquid. Alternatively, some lakes may be ephemeral: differences may be the result of precipitation and ponding of liquid methane and subsequent evaporation or infiltration thereof (Turtle et al., 2009) in the time between observations: ISS in mid-2004 and mid-2005 (equivalent of ~12 and ~25 January) and the RADAR observations starting in late 2007 (equivalent of ~28 February). We will present observations of Titan's meteorology and surface features, documenting seasonal changes and their implications for Titan's active methane cycle and atmospheric circulation.

Turtle, E. P.; Perry, J. E.; McEwen, A. S.; Barbara, J.; Del Genio, A.; West, R. A.; Hayes, A.; Schaller, E.

2010-04-01

92

Correlation of the abundance of betaproteobacteria on mineral surfaces with mineral weathering in forest soils.  

PubMed

Pyrosequencing-based analysis of 16S rRNA gene sequences revealed a significant correlation between apatite dissolution and the abundance of betaproteobacteria on apatite surfaces, suggesting a role for the bacteria belonging to this phylum in mineral weathering. Notably, the cultivation-dependent approach demonstrated that the most efficient mineral-weathering bacteria belonged to the betaproteobacterial genus Burhkolderia. PMID:22798365

Lepleux, C; Turpault, M P; Oger, P; Frey-Klett, P; Uroz, S

2012-10-01

93

Correlation of the Abundance of Betaproteobacteria on Mineral Surfaces with Mineral Weathering in Forest Soils  

PubMed Central

Pyrosequencing-based analysis of 16S rRNA gene sequences revealed a significant correlation between apatite dissolution and the abundance of betaproteobacteria on apatite surfaces, suggesting a role for the bacteria belonging to this phylum in mineral weathering. Notably, the cultivation-dependent approach demonstrated that the most efficient mineral-weathering bacteria belonged to the betaproteobacterial genus Burhkolderia. PMID:22798365

Lepleux, C.; Turpault, M. P.; Oger, P.; Frey-Klett, P.

2012-01-01

94

CHARACTERISTICS OF MICROBURST EVENTS OBSERVED WITH THE NATIONAL WEATHER RADAR TESTBED PHASED ARRAY RADAR  

E-print Network

7.8 CHARACTERISTICS OF MICROBURST EVENTS OBSERVED WITH THE NATIONAL WEATHER RADAR TESTBED PHASED events. Microbursts are small-scale ( in thunderstorms that frequently cause damage to property and are a hazard to aviators. Many severe microbursts

Smith, Travis

95

Evolution of Titan's outer icy shell: Role of ocean crystallization and surface weathering  

NASA Astrophysics Data System (ADS)

The Cassini-Huygens mission has brought evidences for an internal ocean lying under an outer ice shell. The structure and evolution of the outer ice shell and of the internal ocean are essential to understand Titan's surface morphology as well as its atmosphere evolution. The observed shape and the gravity field of Titan provide information on the present-day structure of the H2O mantle, in terms of ocean/ice interface depth and crustal density. By modeling consistently topography and gravity data, we have quantified the amplitudes of ice shell thickness and/or crustal density variations. Moreover, we have constrained the possible viscosity structure of the outer shell and thermal gradients by modeling the topography relaxation rate. Lateral variations in the thickness of the outer ice shell may be explained by heterogeneous ocean crystallization, while surface weathering by liquid hydrocarbons may generate surface erosion and crustal alteration. To determine how these processes affect Titan's dynamics, we model heat and mass transfers between the internal ocean, the ice shell and the atmosphere and we determine the time evolution of long-wavelength topography and surface stress patterns for different evolutionary scenarios. Finally, we compare our predicted maps of surface stress and heat flux anomalies with the global repartition of the morphological features observed by VIMS and Radar.

Lefevre, A.; Tobie, G.; Amit, H.; Cadek, O.; Choblet, G.; Le Mouelic, S.; Mitri, G.; Sotin, C.

2013-12-01

96

Observation of Discrete Surface Solitons  

Microsoft Academic Search

We report the first observation of discrete optical surface solitons at the interface between a nonlinear self-focusing waveguide lattice and a continuous medium. The effect of power on the localization process of these optical self-trapped states at the edge of an AlGaAs waveguide array is investigated in detail. Our experimental results are in good agreement with theoretical predictions.

S. Suntsov; K. G. Makris; D. N. Christodoulides; G. I. Stegeman; A. Haché; R. Morandotti; H. Yang; G. Salamo; M. Sorel

2006-01-01

97

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science  

Microsoft Academic Search

We often look ``through a glass, darkly'' at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers

J. F. Cooper; R. E. Hartle; E. C. Sittler; M. A. McGrath; C. J. Alexander; J. B. Dalton; D. Pascu; C. Paranicas; C. Hibbitts; M. E. Hill; P. D. Cooper; R. E. Johnson; T. A. Cassidy; T. M. Orlando; L. J. Lanzerotti; N. A. Schwadron; K. D. Retherford; R. I. Kaiser; F. Leblanc; S. J. Sturner; R. M. Killen

2009-01-01

98

Laboratory Simulations of Space Weathering of Asteroid Surfaces by Solar Wind Ions.  

NASA Astrophysics Data System (ADS)

Studies into the formation of the terrestrial planets rely on the analysis of asteroids and meteorites. Asteroids are solar system remnants from the planetary formation period. By characterizing their mineralogical composition we can better constrain the formation and evolution of the inner planets.Remote sensing is the primary means for studying asteroids. Sample return missions, such as Hayabusa, are complex and expensive, hence we rely on asteroid reflectance spectra to determine chemical composition. Links have been made and debated between meteorite classes and asteroid types [1, 2]. If such relationships can be confirmed, then meteorites would provide a low cost asteroid sample set for study. However, a major issue in establishing this link is the spectral differences between meteorite samples and asteroid surfaces. The most commonly invoked explanation for these differences is that the surfaces of asteroids are space weathered [2, 3]. The dominant mechanism for this weathering is believed to be solar-wind ion irradiation [2, 4, 5]. Laboratory simulations of space weathering have demonstrated changes in the general direction required to alter spectra from unweathered meteorite samples to asteroid observations [3, 6 -10], but many open questions remain and we still lack a comprehensive understanding. We propose to explore the alleged connection of ordinary chondrite (OC) meteorites to S-type asteroids through a series of systematic laboratory simulations of solar-wind space weathering of asteroid surface materials. Here we describe the issue in more detail and describe the proposed apparatus. [1] Chapman C. R. (1996) Meteorit. Planet. Sci., 31, 699-725. [2] Chapman C. R. (2004), Annu. Rev. Earth Planet. Sci., 32, 539-567. [3] Hapke B. (2001) J. Ge-ophys. Res., 106, 10039-10074. [4] Pieters C.M. et al. (2000) Meteorit. Planet. Sci., 35, 1101-1107. [5] Ver-nazza P. et al. (2009) Nature, 458, 993-995. [6] Stra-zulla G. et al. (2005) Icarus, 174, 31-35 (2005). [7] Brunetto R and Strazzulla G (2005) Icarus, 179, 265-273. [8] Marchi S et al. (2005) Astron. Astrophys., 443, 769-775. [9] Loeffler M. J. et al. (2009) J. Geo-phys. Res., 114, E03003. [10] Fu X. et al. (2012) Ica-rus, 219, 630-640

Miller, Kenneth A.; De Ruette, Nathalie; Harlow, George; Domingue, Deborah L.; Savin, Daniel Wolf

2014-06-01

99

Plymouth State Weather Center  

NSDL National Science Digital Library

The Plymouth State Weather Center provides a variety of weather information, including a tropical weather menu with current and archived data on tropical depressions, storms, or hurricanes in the Atlantic or Eastern Pacific Oceans. An interactive Weather Product Generator allows students to make their own surface data maps and meteograms (24-hour summaries of weather at a specific location), and view satellite imagery. There are also interactive weather maps for the U.S., Canada, and Alaska that display the latest observations, and text servers which provide current written observations for New England and North America. A set of past and current weather data products provides information on minimum and maximum temperatures, wind chill, and heat index. In addition, there are collections of satellite loops/movies, radar/lightning images, loops, and movies, and a set of tutorials on clouds, the sun and its effects on the environment, and balanced atmospheric flows.

100

Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroidal Space Weathering Studies  

NASA Astrophysics Data System (ADS)

Mercury's regolith, derived from the crustal bedrock, has been altered by a set of space weathering processes. Before we can interpret crustal composition, it is necessary to understand the nature of these surface alterations. The processes that space weather the surface are the same as those that form Mercury's exosphere (micrometeoroid flux and solar wind interactions) and are moderated by the local space environment and the presence of a global magnetic field. To comprehend how space weathering acts on Mercury's regolith, an understanding is needed of how contributing processes act as an interactive system. As no direct information (e.g., from returned samples) is available about how the system of space weathering affects Mercury's regolith, we use as a basis for comparison the current understanding of these same processes on lunar and asteroidal regoliths as well as laboratory simulations. These comparisons suggest that Mercury's regolith is overturned more frequently (though the characteristic surface time for a grain is unknown even relative to the lunar case), more than an order of magnitude more melt and vapor per unit time and unit area is produced by impact processes than on the Moon (creating a higher glass content via grain coatings and agglutinates), the degree of surface irradiation is comparable to or greater than that on the Moon, and photon irradiation is up to an order of magnitude greater (creating amorphous grain rims, chemically reducing the upper layers of grains to produce nanometer scale particles of metallic iron, and depleting surface grains in volatile elements and alkali metals). The processes that chemically reduce the surface and produce nanometer-scale particles on Mercury are suggested to be more effective than similar processes on the Moon. Estimated abundances of nanometer-scale particles can account for Mercury's dark surface relative to that of the Moon without requiring macroscopic grains of opaque minerals. The presence of nanometer-scale particles may also account for Mercury's relatively featureless visible-near-infrared reflectance spectra. Characteristics of material returned from asteroid 25143 Itokawa demonstrate that this nanometer-scale material need not be pure iron, raising the possibility that the nanometer-scale material on Mercury may have a composition different from iron metal [such as (Fe,Mg)S]. The expected depletion of volatiles and particularly alkali metals from solar-wind interaction processes are inconsistent with the detection of sodium, potassium, and sulfur within the regolith. One plausible explanation invokes a larger fine fraction (grain size <45 ?m) and more radiation-damaged grains than in the lunar surface material to create a regolith that is a more efficient reservoir for these volatiles. By this view the volatile elements detected are present not only within the grain structures, but also as adsorbates within the regolith and deposits on the surfaces of the regolith grains. The comparisons with findings from the Moon and asteroids provide a basis for predicting how compositional modifications induced by space weathering have affected Mercury's surface composition.

Domingue, Deborah L.; Chapman, Clark R.; Killen, Rosemary M.; Zurbuchen, Thomas H.; Gilbert, Jason A.; Sarantos, Menelaos; Benna, Mehdi; Slavin, James A.; Schriver, David; Trávní?ek, Pavel M.; Orlando, Thomas M.; Sprague, Ann L.; Blewett, David T.; Gillis-Davis, Jeffrey J.; Feldman, William C.; Lawrence, David J.; Ho, George C.; Ebel, Denton S.; Nittler, Larry R.; Vilas, Faith; Pieters, Carle M.; Solomon, Sean C.; Johnson, Catherine L.; Winslow, Reka M.; Helbert, Jörn; Peplowski, Patrick N.; Weider, Shoshana Z.; Mouawad, Nelly; Izenberg, Noam R.; McClintock, William E.

2014-05-01

101

Analysis of fog occurrence on E11-A75 Motorway, with weather station data in relation to satellite observation  

NASA Astrophysics Data System (ADS)

Transport is often disturbed in wintertime by fog occurrence causing delay. Fog may also be responsible for dramatic accidents causing injuries and fatalities. For meteorological weather services, fog is defined as when visibility is less than 1000 m. However, for road traffic, when visibility becomes less than 200 m, fog is considered a traffic hazard for road transport. Fog forecast remains a difficult task. Satellite observation combined with surface measurements by a network of road weather stations can provide short-term information that could be useful to assist traffic authorities in taking decisions relating to traffic control measures or drivers information. Satellite images allow to identify cloud types and to establish a map of the risk of fog occurrence. The surface measurements help to discriminate between low clouds and fog. The analysis method has already been tested last winter on some case studies on the motorway E11-A75 in Auvergne region in France, thanks to a network of 15 weather stations along the 300 km of motorway. In the highest area that is between 580 and 1100 m, the value of the relative humidity has been analysed in relation to the visibility measured by a diffusiometer and the observations of road maintenance staff. The main results will be presented and connected to the traditional synoptic network of Météo-France. In order to improve the map of fog risks, the requirement to have relevant data has been pointed out, especially for the relative humidity near the ground surface (i.e. 2 m above the ground). To go further in this investigation, one weather station, at the Col de la Fageole, has been identified as having the greatest occurrence of dense fog, i.e. less than 200 m. Then it has been decided to enrich the instrumentation at this observation point later on with a present weather sensor and with a camera. This paper will focus on the physical data of the weather station. It will be examined how the additional data of the new sensor, the meteorological visibility and the discrimination of the nature of precipitation will help to improve the analysis.

Colomb, M.; Bernardin, F.; Favier, B.; Mallet, E.; Laurantin, O.

2010-07-01

102

Surface Meteorological Observation System (SMOS)  

NSDL National Science Digital Library

These middle/junior high school activities require students to find and graph factors such as wind chill and relative humidity for up to a month, drawing from datasets available on the Internet or from local sources. Students then hypothesize relationships between pairs of factors, and test their ideas using data from a site in Oklahoma with a Surface Meteorological Observation System (SMOS). The activities are part of the Atmospheric Visualization Collection (AVC), which focuses on data from the Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) Cloud and Radiation Testbed site.

Tim McCollum

2003-01-01

103

Rates of oxidative weathering on the surface of Mars  

NASA Technical Reports Server (NTRS)

A model of acid weathering is proposed for the iron-rich basalts on Mars. Aqueous oxidation of iron sulfides released SO4(2-) and H(+) ions that initiated the dissolution of basaltic ferromagnesian silicates and released Fe(2+) ions. The Fe(2+) ions eventually underwent ferrolysis reactions and produced insoluble hydrous ferric oxide phases. Measurements of the time-dependence of acid weathering reactions show that pyrrhotite is rapidly converted to pyrite plus dissolved ferrous iron, the rate of pyrite formation decreasing with rising pH and lower temperatures. On Mars, oxidation rates of dissolved Fe(2+) ions in equatorial melt-waters in contact with the atmosphere are estimated to lie in the range 0.3-3.0 ppb Fe/yr over the pH range 2 to 6. Oxidation of Fe(2+) ions is estimated to be extremely slow in brine eutectic solutions that might be present on Mars and to be negligible in the frozen regolith.

Burns, Roger G.; Fisher, Duncan S.

1993-01-01

104

Simulation studies of the impact of advanced observing systems on numerical weather prediction  

NASA Technical Reports Server (NTRS)

To study the potential impact of advanced passive sounders and lidar temperature, pressure, humidity, and wind observing systems on large-scale numerical weather prediction, a series of realistic simulation studies between the European Center for medium-range weather forecasts, the National Meteorological Center, and the Goddard Laboratory for Atmospheric Sciences is conducted. The project attempts to avoid the unrealistic character of earlier simulation studies. The previous simulation studies and real-data impact tests are reviewed and the design of the current simulation system is described. Consideration is given to the simulation of observations of space-based sounding systems.

Atlas, R.; Kalnay, E.; Susskind, J.; Reuter, D.; Baker, W. E.; Halem, M.

1984-01-01

105

THE LINK BETWEEN CLAY MINERAL WEATHERING AND THE FORMATION OF NI SURFACE PRECIPITATES  

E-print Network

THE LINK BETWEEN CLAY MINERAL WEATHERING AND THE FORMATION OF NI SURFACE PRECIPITATES Andreas C minerals may proceed via formation of surface precipitates, which may lead to a significant long the formation of several mineral phases with distinct solubilities. While turbostratic a-type metal hydroxides

Sparks, Donald L.

106

Weather impacts on space operations  

NASA Astrophysics Data System (ADS)

The efforts of the 45th Weather Squadron of the USAF to provide weather support to Patrick Air Force Base, Cape Canaveral Air Force Station, Eastern Range, and the Kennedy Space Center are discussed. Its weather support to space vehicles, particularly the Space Shuttle, includes resource protection, ground processing, launch, and Ferry Flight, as well as consultations to the Spaceflight Meteorology Group for landing forecasts. Attention is given to prelaunch processing weather, launch support weather, Shuttle launch commit criteria, and range safety weather restrictions. Upper level wind requirements are examined. The frequency of hourly surface observations with thunderstorms at the Shuttle landing facility, and lightning downtime at the Titan launch complexes are illustrated.

Madura, J.; Boyd, B.; Bauman, W.; Wyse, N.; Adams, M.

107

Convectively Driven Mesoscale Weather Systems Aloft. Part I: Observations.  

NASA Astrophysics Data System (ADS)

Examination of NMC upper tropospheric analyses (300, 200 and 150 mb charts) indicates that significant perturbations are present in the wind fields in the vicinity of intense meso- scale (250-2500 km) thunder-storm complexes (identified utilizing enhanced IR satellite imagery). This effect is investigated for each of 10 mesoscale convective complexes. Since the LFM convective adjustment procedure cannot infuse large amounts of mass, momentum and moisture into the upper troposphere and lower stratosphere, the 12 h LFM predicted winds are used as an indication of the unperturbed environmental flow. An estimate of the convective perturbation is obtained by subtracting the LFM predicted 200 mb winds from the observed winds. A large anticyclonic flow perturbation is present in each of the 10 events. Wind speed perturbations at individual sounding locations are commonly 10-20 m s1 with maximum values as great as 38 m s1. Detailed case analyses for two events are presented to illustrate these effects.The predicted and observed fields are objectively analyzed over a common grid to develop a composite field for the 10 cases. The composite difference field is not only similar to that of the individual cases but it is also found that significant perturbations occur only in the vicinity of the convective complexes. Macroscale and mesoscale characteristics of these composite flow fields are also examined utilizing an objective technique for scale separation. Other characteristics of the perturbed fields are presented and implications of the convectively forced perturbations are discussed.

Fritsch, J. M.; Maddox, R. A.

1981-01-01

108

Offline land surface temperature assimilation in mumerical weather prediction output  

Technology Transfer Automated Retrieval System (TEKTRAN)

Land surface temperature plays an important role in land surface processes, and it is a key input to physically-based retrieval algorithms of important hydrological states and fluxes, such as soil moisture and evaporation. For this reason there are many independent estimates of land surface temperat...

109

Space weathering of asteroidal surfaces. Influence on the UV-Vis spectra  

NASA Astrophysics Data System (ADS)

Context. The surfaces of airless bodies in the Solar System are continuously altered by the bombardment of micrometeoroids and irradiation by solar wind, flares, and cosmic particles. Major effects of this process - space weathering - are darkening and “reddening” of the spectra of surface materials, as well as a “degrading” of absorption features. Aims: We studied the changes induced by energetic ion irradiation in the ultraviolet-visual-near-infrared (UV-Vis-NIR) (0.2-0.98 ?m) reflectance spectra of targets selected to mimic the surfaces of airless bodies in the inner Solar System. Our chosen targets are olivine pellets, pure or covered by an organic polymer (polystyrene), which is transparent before irradiation. Polystyrene is used as a template for organic matter of low volatility that can be present on asteroidal surfaces. Moreover we measured the changes induced by ion irradiation in the absorption coefficient of the polymer. The purpose was to have a tool to better compare laboratory with observed spectra and distinguish between planetary objects with pure silicate surfaces and those whose surface is covered by organic matter exposed to cosmic ion bombardment. Methods: The samples were irradiated in vacuum, at room temperature, with 200 keV protons or 200-400 keV argon ions. Before, during, and after irradiation diffuse reflectance spectra were acquired. Polystyrene films were also deposited on quartz substrates and irradiated while transmittance spectra were recorded. Results: We measured the variations of the absorption coefficient of polystyrene as a function of ion fluence. We showed that after ion irradiation the diffuse reflectance spectra of the samples covered by organics exhibit a much more significant variation than those of pure silicates. The spectra of targets made of olivine plus polystyrene can be fitted by using the measured absorption coefficient of polystyrene. Conclusions: The results obtained for pure olivine extend to the UV the spectral range of previous experiments. The data concerning the absorption coefficient of polystyrene are available on our web site (http://web.ct.astro.it/weblab/dbindex.html) and can be used to compare laboratory with astronomical spectra. This will possibly allow us to obtain information about organic matter on the surface of a given object, as well as on the relevance of the exposure to cosmic ions (space weathering). Data table is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/517/A60

Ka?uchová, Z.; Baratta, G. A.; Garozzo, M.; Strazzulla, G.

2010-07-01

110

Porosity and surface area evolution during weathering of two igneous rocks  

NASA Astrophysics Data System (ADS)

During weathering, rocks release nutrients and store water vital for growth of microbial and plant life. Thus, the growth of porosity as weathering advances into bedrock is a life-sustaining process for terrestrial ecosystems. Here, we use small-angle and ultra small-angle neutron scattering to show how porosity develops during initial weathering under tropical conditions of two igneous rock compositions, basaltic andesite and quartz diorite. The quartz diorite weathers spheroidally while the basaltic andesite does not. The weathering advance rates of the two systems also differ, perhaps due to this difference in mechanism, from 0.24 to 100 mm kyr-1, respectively. The scattering data document how surfaces inside the feldspar-dominated rocks change as weathering advances into the protolith. In the unaltered rocks, neutrons scatter from two types of features whose dimensions vary from 6 nm to 40 ?m: pores and bumps on pore-grain surfaces. These features result in scattering data for both unaltered rocks that document multi-fractal behavior: scattering is best described by a mass fractal dimension (Dm) and a surface fractal dimension (Ds) for features of length scales greater than and less than ˜1 ?m, respectively. In the basaltic andesite, Dm is approximately 2.9 and Ds is approximately 2.7. The mechanism of solute transport during weathering of this rock is diffusion. Porosity and surface area increase from ˜1.5% to 8.5% and 3 to 23 m2 g-1 respectively in a relatively consistent trend across the mm-thick plagioclase reaction front. Across this front, both fractal dimensions decrease, consistent with development of a more monodisperse pore network with smoother pore surfaces. Both changes are consistent largely with increasing connectivity of pores without significant surface roughening, as expected for transport-limited weathering. In contrast, porosity and surface area increase from 1.3% to 9.5% and 1.5 to 13 m2 g-1 respectively across a many cm-thick reaction front in the spheroidally weathering quartz diorite. In that rock, Dm is approximately 2.8 and Ds is approximately 2.5 prior to weathering. These two fractals transform during weathering to multiple surface fractals as micro-cracking reduces the size of diffusion-limited subzones of the matrix. Across the reaction front of plagioclase in the quartz diorite, the specific surface area and porosity change very little until the point where the rock disaggregates into saprolite. The different patterns in porosity development of the two rocks are attributed to advective infiltration plus diffusion in the rock that spheroidally fractures versus diffusion-only in the rock that does not. Fracturing apparently diminishes the size of the diffusion-limited parts of the spheroidally weathering rock system to promote infiltration of meteoric fluids, therefore explaining the faster weathering advance rate into that rock.

Navarre-Sitchler, Alexis K.; Cole, David R.; Rother, Gernot; Jin, Lixin; Buss, Heather L.; Brantley, Susan L.

2013-05-01

111

Porosity and surface area evolution during weathering of two igneous rocks  

SciTech Connect

During weathering, rocks release nutrients and storewater vital for growth ofmicrobial and plant life. Thus, the growth of porosity as weathering advances into bedrock is a life-sustaining process for terrestrial ecosystems. Here, we use small-angle and ultra small-angle neutron scattering to show how porosity develops during initial weathering under tropical conditions of two igneous rock compositions, basaltic andesite and quartz diorite. The quartz diorite weathers spheroidally while the basaltic andesite does not. The weathering advance rates of the two systems also differ, perhaps due to this difference in mechanism, from 0.24 to 100 mm kyr1, respectively. The scattering data document how surfaces inside the feldspar-dominated rocks change as weathering advances into the protolith. In the unaltered rocks, neutrons scatter fromtwo types of featureswhose dimensions vary from6 nmto 40 lm: pores and bumps on pore grain surfaces. These features result in scattering data for both unaltered rocks that document multi-fractal behavior: scattering is best described by amass fractal dimension (Dm) and a surface fractal dimension (Ds) for features of length scales greater than and less than 1 lm, respectively. In the basaltic andesite, Dm is approximately 2.9 and Ds is approximately 2.7. The mechanism of solute transport during weathering of this rock is diffusion. Porosity and surface area increase from 1.5%to 8.5%and 3 to 23 m2 g1 respectively in a relatively consistent trend across themm-thick plagioclase reaction front. Across this front, both fractal dimensions decrease, consistentwith development of amoremonodisperse pore networkwith smoother pore surfaces. Both changes are consistent largely with increasing connectivity of pores without significant surface roughening, as expected for transport-limited weathering. In contrast, porosity and surface area increase from 1.3% to 9.5% and 1.5 to 13 m2 g1 respectively across a many cm-thick reaction front in the spheroidally weathering quartz diorite. In that rock, Dm is approximately 2.8 andDs is approximately 2.5 prior to weathering. These two fractals transform during weathering to multiple surface fractals as micro-cracking reduces the size of diffusion-limited subzones of thematrix.Across the reaction front of plagioclase in the quartz diorite, the specific surface area and porosity change very little until the pointwhere the rock disaggregates into saprolite. The different patterns in porosity development of the two rocks are attributed to advective infiltration plus diffusion in the rock that spheroidally fractures versus diffusion-only in the rock that does not. Fracturing apparently diminishes the size of the diffusion-limited parts of the spheroidally weathering rock system to promote infiltration of meteoric fluids, thereforeexplaining the faster weathering advance rate into that rock.

Navarre-Sitchler, Alexis [Colorado School of Mines, Golden; Cole, David [Ohio State University; Rother, Gernot [ORNL; Jin, Lixin [University of Texas, El Paso; Buss, Heather [University of Bristol, UK; Brantley, S. L. [Pennsylvania State University, University Park, PA

2013-01-01

112

Optimal Sites for Supplementary Weather Observations: Simulation with a Small Model  

Microsoft Academic Search

ABSTRACT Anticipating the opportunity to make,supplementary,observations at locations that can depend upon the current weather situation, the question is posed as to what strategy should be adopted to select the locations, if the greatest improvement in analyses and forecasts is to be realized. To seek a preliminary answer, the authors introduce a model consisting of 40 ordinary differential equations, with

Edward N. Lorenz; Kerry A. Emanuel

1998-01-01

113

Weather Observations and a Tentative Meteorological Analysis of the Period May  

E-print Network

Weather Observations and a Tentative Meteorological Analysis of the Period May to July 1588 K. CRU RP6 (1978) Douglas KS, Lamb HH & Loader C A meteorological study of July to October 1588 Meteorological Analysis of the Period May to July 1588. CRU RP7 (1980) Perry AH & Fearnside T Northern Hemisphere

Feigon, Brooke

114

Total Lightning Observations of Extreme Weather Events over the Contiguous United States  

Microsoft Academic Search

The overall objective is to investigate total lightning characteristics of extreme weather events over the contiguous United States (CONUS) using TRMM (Tropical Rainfall Measuring Mission) LIS (Lightning Image Sensor) and OTD (Optical Transient Detector) satellite observations. A large LIS (10+ years) and OTD (5 years) data base is available to study the instantaneous total or cloud-to-ground (CG) plus intracloud (IC)

L. D. Carey; W. A. Petersen; H. J. Christian

2008-01-01

115

Climatological weather observations Rainfall records at the University date back to 1901, with comprehensive  

E-print Network

Climatological weather observations Rainfall records at the University date back to 1901 1974 ­ a small whirlwind was sighted at Earley Gate ­ there was a `roaring' sound but no damage collaborations The Observatory also enables industrial and external collaborations by providing a controlled

Matthews, Adrian

116

VALIDATION OF RAIN RATE RETRIEVALS FROM SEVIRI USING WEATHER RADAR OBSERVATIONS  

E-print Network

VALIDATION OF RAIN RATE RETRIEVALS FROM SEVIRI USING WEATHER RADAR OBSERVATIONS R. A. Roebeling, The Netherlands ABSTRACT This paper presents a method to detect precipitation and estimate rain rates using cloud calculates rain rates from cloud liquid water path (LWP), particle effective radius, cloud thermodynamic

Stoffelen, Ad

117

Comments on: Antarctic Automatic Weather Station Program: 30 Years of Polar Observations  

E-print Network

Recently Lazzara et al. (2012) presented a review of the technical and scientific progress in deployment, data collection and analysis of the Automated Weather Stations (AWS) in the Antarctic. In the subsection entitled Science Applications using AWS Observations, the authors briefly account for several scientific occurrences of meteorological data collected by AWS.

Sienicki, Krzysztof

2013-01-01

118

Evolution of Stratocumulus Over Land: Comparison of Ground and Aircraft Observations with Numerical Weather Prediction Simulations  

NASA Astrophysics Data System (ADS)

Forecasting of low cloud continues to challenge numerical weather prediction. With this in mind, surface and airborne observations were made over East Anglia, UK, during March 2011 to investigate stratus and stratocumulus advecting from the sea over land. Four surface sites were deployed at various distances inland aligned approximately along the flow. In situ data include cloud-droplet measurements from an aircraft operating off the coast and a tethered balloon 100 km inland. Comparisons of thermodynamic and cloud properties are made with Met Office operational model simulations at horizontal resolutions of 4 and 1.5 km. The clouds contained droplet concentrations up to 600 cm^{-3} within polluted outflow off Europe. These measurements were compared to three different model schemes for predicting droplet concentration: two of them perform well at low to moderate concentrations but asymptote to 375 cm^{-3} . Microwave radiometers at the ground sites retrieved liquid water paths that reduced with distance inland and were generally below 200 g m^{-2} . The modelled water path performs well upstream but more erratically far inland. Comparisons of thermodynamic profiles are made within both Lagrangian and Eulerian frameworks and show the model predicted changes in equivalent potential temperature generally within 1 K, with occasional errors of 2 K or more. The modelled cloud-top temperatures were in good agreement with the observations down to - 7° C, but the magnitude of the temperature inversion, although good at times, was too small by on average 1.6 K. The different simulations produced different cloud-top water contents due to a combination of resolution and scientific upgrades to the model, but they generally underestimate the amount of cloud water. Major changes, such as the mesoscale temporary cloud breaks on 2 March 2011 and the complete clearance on 4 March, were seemingly predicted by the model for the correct reasons.

Osborne, Simon R.; Abel, Steven J.; Boutle, Ian A.; Marenco, Franco

2014-07-01

119

Ensemble Data Assimilation to Characterize Surface-Layer Errors In Numerical Weather Prediction Models  

NASA Astrophysics Data System (ADS)

Experiments with the single-column implementation of the Weather Research and Forecasting mesoscale model provide a basis for deducing land-atmosphere coupling errors in the model. Coupling occurs both through heat and moisture fluxes through the land-atmosphere interface and roughness sub-layer, and turbulent heat, moisture, and momentum fluxes through the atmospheric surface layer. This work primarily addresses the turbulent fluxes, which are parameterized following Monin-Obukhov similarity theory applied to the atmospheric surface layer. By combining ensemble data assimilation and parameter estimation, the model error can be characterized. Ensemble data assimilation of 2-m temperature and water vapor mixing ratio, and 10-m wind components, forces the model to follow observations during a month-long simulation for a column over the well-instrumented ARM Central Facility near Lamont, OK. One-hour errors in predicted observations are systematically small but non-zero, and the systematic errors measure bias as a function of local time of day. Analysis increments for state elements nearby (15-m AGL) can be too small or have the wrong sign, indicating systematically biased covariances and model error. Experiments using the ensemble filter to objectively estimate a parameter controlling the thermal land-atmosphere coupling show that the parameter adapts to offset the model errors, but that the errors cannot be eliminated. Results suggest either structural error or further parametric error that may be difficult to estimate. Experiments omitting atypical observations such as soil and flux measurements lead to qualitatively similar deductions, showing potential for assimilating common in-situ observations as an inexpensive framework for deducing and isolating model errors. We finish by presenting recent results from a deeper examination of the second-moment ensemble statistics, which demonstrate the effect of assimilation on the coupling through the stability function in the atmospheric surface layer scheme.

Hacker, Joshua; Angevine, Wayne

2013-04-01

120

Conversion of bedrock to soil and feedback processes between the surface and the weathering front in a deeply weathered regolith, Central Sri Lankan Highlands  

NASA Astrophysics Data System (ADS)

In the Sri Lankan highlands denudation rates and chemical weathering rates represent the low-end-member in global weathering rates [1, 2]. Here we explore the causes for these low rates by a detailed soil-mineralogical study of a highly weathered deep saprolite profile developed from charnockite bedrock. Spheroidal weathering of the bedrock characterized the weathering front where rounded corestones are produced at the rock-saprolite interface. The first mineral attacked by weathering was found to be pyroxene but plagioclase is the first mineral depleted to near-completion at the corestone-saprolite-boundary. Weathering of pyroxene is initiated by in situ iron oxidation, leading to an increase of porosity due to micro-cracking [3]. The accrued micro cracks allow for fluid transport and the dissolution of biotite and plagioclase. The strong plagioclase weathering leads to formation of high secondary porosity over a small distance and the final disaggregation of bedrock to saprolite. Sequential extraction showed that the first secondary phases are amorphous oxides from which secondary minerals (gibbsite, kaolinite, goethite and minor amounts of smectites) precipitate. Modeling of the strain formation due to increasing volume during iron oxidation in pyroxene and biotite showed that spheroidal weathering can be explained with this process only if the formation of secondary porosity, due to a negative volume budget during primary mineral weathering to secondary phases, occurs. As oxidation is the first occurring reaction, O2 is a rate limiting factor for chemical weathering in this setting. Hence the supply of oxygen and the consumption at depth connects processes at the weathering front with those at the surface as a feedback mechanism. Advective and diffusive transport modeling shows that the feedback will be much more pronounced with dominating diffusive transport. Due to the low porosity of the bedrock the O2 transport in the pristine bedrock occurs via diffusion. The slow weathering rate is, beside tectonic quiescence, related to this feedback and to lithological factors such as low porosity and the amount of Fe-bearing primary minerals. 1. Hewawasam, T., et al., Slow advance of the weathering front during deep, supply-limited saprolite formation in the tropical Highlands of Sri Lanka. Geochimica et Cosmochimica Acta, 2013. 118: p. 202-230. 2. von Blanckenburg, F., T. Hewawasam, and P. Kubik, Cosmogenic nuclide evidence for low weathering and denudation in the wet tropical Highlands of Sri Lanka. J. Geoph. Res., 2004. 109: p. doi10.1029/2003JF000049. 3. Buss, H.L., et al., Weathering of the Rio Blanco quartz diorite, Luquillo Mountains, Puerto Rico: Coupling oxidation, dissolution, and fracturing. Geochimica et Cosmochimica Acta, 2008. 72(18): p. 4488-4507.

Behrens, Ricarda; Bouchez, Julien; Schuessler, Jan A.; Dultz, Stefan; Hewawasam, Tilak; von Blanckenburg, Friedhelm

2014-05-01

121

JPL's Real-Time Weather Processor project (RWP) metrics and observations at system completion  

NASA Technical Reports Server (NTRS)

As an integral part of the overall upgraded National Airspace System (NAS), the objective of the Real-Time Weather Processor (RWP) project is to improve the quality of weather information and the timeliness of its dissemination to system users. To accomplish this, an RWP will be installed in each of the Center Weather Service Units (CWSUs), located in 21 of the 23 Air Route Traffic Control Centers (ARTCCs). The RWP System is a prototype system. It is planned that the software will be GFE and that production hardware will be acquired via industry competitive procurement. The ARTCC is a facility established to provide air traffic control service to aircraft operating on Instrument Flight Rules (IFR) flight plans within controlled airspace, principally during the en route phase of the flight. Covered here are requirement metrics, Software Problem Failure Reports (SPFRs), and Ada portability metrics and observations.

Loesh, Robert E.; Conover, Robert A.; Malhotra, Shan

1990-01-01

122

How to Use the Weather Program  

NSDL National Science Digital Library

This undergraduate meteorology tutorial introduces The Weather Program, available from NCAR (the National Center for Atmospheric Research). The Weather program obtains weather data for requested stations and times. This tutorial provides students with experience with the interfaces, Netscape and a shell window. Students learn to access surface observations both decoded and raw and National Weather Service forecasts, watches and warnings. They learn to determine where warnings are active and to find specific requested weather information.

John Nielsen-Gammon

1996-01-01

123

Draft Genome Sequence of Rhizobium sp. H41, a Rock-Weathering Bacterium from a Weathered Rock Surface.  

PubMed

Rhizobium sp. H41 isolated from weathered tuff can weather tuff and release Fe, Si, and Al from the rock under nutrient-poor conditions. Here, we report the draft genome sequence of strain H41, which may facilitate a better understanding of the molecular mechanism involved in rock weathering by the bacterium. PMID:25377707

Xi, Jun; Sheng, Xiafang; He, Linyan

2014-01-01

124

Weathering pits as indicators of the relative age of granite surfaces in the Cairngorm mountains, Scotland  

USGS Publications Warehouse

Weathering pits 1-140 cm deep occur on granite surfaces in the Cairngorms associated with a range of landforms, including tors, glacially exposed slabs, large erratics and blockfields. Pit depth is positively correlated with cosmogenic exposure age, and both measures show consistent relationships on individual rock landforms. Rates of pit deepening are non-linear and a best fit is provided by the sigmoidal function D = b1+ exp(b2+b3/t). The deepest pits occur on unmodified tor summits, where 10 Be exposure ages indicate that surfaces have been exposed to weathering for a minimum of 52-297 ka. Glacially exposed surfaces with pits 10-46 cm deep have given 10 Be exposure durations of 21-79 ka, indicating exposure by glacial erosion before the last glacial cycle. The combination of cosmogenic exposure ages with weathering pit depths greatly extends the area over which inferences can be made regarding the ages of granite surfaces in the Cairngorms. Well-developed weathering pits on glacially exposed surfaces in other granite areas are potential indicators of glacial erosion before the Last Glacial Maximum. ?? Swedish Society for Anthropology and Geography.

Hall, A.M.; Phillips, W.M.

2006-01-01

125

The Main Pillar: Assessment of Space Weather Observational Asset Performance Supporting Nowcasting, Forecasting and Research to Operations  

NASA Astrophysics Data System (ADS)

Sporadically, the Sun unleashes severe magnetic activity into the heliosphere. The specific solar/heliospheric phenomena and their effects on humans, technology and the wider geospace environment include a) high-intensity emissions from the Sun causing radio blackouts and (surface) charging, b) particle acceleration in the solar corona leading to high dose rates of ionizing radiation in exposed materials that can trigger single event upsets in electronic components of space hardware, or temporal/permanent damage in tissue, c) arrivals of fast-moving coronal mass ejections with embedded enhancements of magnetic fields that can cause strong ionospheric disturbances affecting radio communications and induce out-of-spec currents in power lines near the surface. Many of the effects could now be forecast with higher fidelity than ever before. However, forecasting critically depends upon availability of timely and reliable observational data. It is therefore crucial to understand how observational assets perform during periods of severe space weather. This paper analyzes and documents the status of the existing and upcoming observational capabilities for forecasting, and discusses how the findings may impact space weather research and its transition to operations.

Posner, A.; Hesse, M.; St. Cyr, C.

2012-12-01

126

Chemical Weathering of Black Shales and Rare Earth Element Composition of Surface Waters and Groundwater  

NASA Astrophysics Data System (ADS)

Weathering processes dominate the dissolved and suspended loads of most of the world's major rivers. Among sedimentary rocks, black shales are particularly sensitive to chemical weathering. Therefore, shale systems are useful for investigating the partitioning of chemical elements during chemical weathering. Recent studies, such as those by Peucker-Ehrenbrink, Ravizza and others, link chemical weathering of black shales to changes in marine isotopic composition. Rare earth elements (REE) have a unique chemistry and are ideal for such tracer studies. We explored the effect of modern chemical weathering of black shales on the hydrochemistry of surface and groundwaters in the Mohawk Valley of New York State. This region provides an ideal site for the investigation of trace element remobilization during the chemical weathering of black shales. In this region, surface and groundwaters, in intimate contact with black shales and have high dissolved metal concentrations presumably due to water-rock interactions. The extent to which the dissolved REE composition of the surface and ground waters retains the rock signature is, in someway related to the length of time that the water remains in contact with the rock. We compared the REE compositions of surface and groundwaters in areas draining black shale to those of waters draining regions of dolostone-limestone to explore the extent of metal release due to chemical weathering. Shale normalized REE patterns for stream waters exhibit slight heavy REE enrichments and, at some locations, LREE depletion. REE patterns of the waters normalized to their respective sediments show some LREE depletion. However, waters associated with the Little Falls dolomite show fractionation predominantly enriched in the heavy REEs. Differences between the black shale sites, recorded as light REE depletion and/or middle REE enrichment, may be related to the discharge of the streams and the total dissolved solids. The dissolved REE chemistry of rivers draining the limestone-dolostone facies to the north and west of the black shale facies is dominated by the Ln-carbonate species. REE speciation in the black shale sites when compared to the dolomitic sites show interesting features. For example, the "dolomite" lake exhibits a significant amount of free metal species as well as lanthanide-fluoride complexation. Our preliminary results indicate that the surface and groundwaters discretely record metal release from black shales. These data lend further credence to the hypothesis that black shale weathering may significantly contribute to the ocean metal budget.

Hannigan, R. E.; Johannesson, K. H.

2001-05-01

127

Superhydrophobic Aluminum Surfaces: Preparation routes, properties and artificial weathering impact  

Microsoft Academic Search

Among the materials that can show superhydrophobic properties are hydrophilic metals which must undergo a sequential treatment, including roughening and hydrophobic coating. This contribution presents various preparation routes along with characterization work employing dynamic contact angle measurements (CA), scanning electron microscopy (SEM) and spec- trometric techniques (FT-IRRAS, XPS, EIS). Micro-rough surfaces of pure and alloyed aluminum were generated most easily

M. Thieme; C. Blank; A. Pereira de Oliveira; H. Worch; R. Frenzel; S. Höhne

128

Cockpit weather information needs  

NASA Technical Reports Server (NTRS)

The primary objective is to develop an advanced pilot weather interface for the flight deck and to measure its utilization and effectiveness in pilot reroute decision processes, weather situation awareness, and weather monitoring. Identical graphical weather displays for the dispatcher, air traffic control (ATC), and pilot crew should also enhance the dialogue capabilities for reroute decisions. By utilizing a broadcast data link for surface observations, forecasts, radar summaries, lightning strikes, and weather alerts, onboard weather computing facilities construct graphical displays, historical weather displays, color textual displays, and other tools to assist the pilot crew. Since the weather data is continually being received and stored by the airborne system, the pilot crew has instantaneous access to the latest information. This information is color coded to distinguish degrees of category for surface observations, ceiling and visibilities, and ground radar summaries. Automatic weather monitoring and pilot crew alerting is accomplished by the airborne computing facilities. When a new weather information is received, the displays are instantaneously changed to reflect the new information. Also, when a new surface or special observation for the intended destination is received, the pilot crew is informed so that information can be studied at the pilot's discretion. The pilot crew is also immediately alerted when a severe weather notice, AIRMET or SIGMET, is received. The cockpit weather display shares a multicolor eight inch cathode ray tube and overlaid touch panel with a pilot crew data link interface. Touch sensitive buttons and areas are used for pilot selection of graphical and data link displays. Time critical ATC messages are presented in a small window that overlays other displays so that immediate pilot alerting and action can be taken. Predeparture and reroute clearances are displayed on the graphical weather system so pilot review of weather along the route can be accomplished prior to pilot acceptance of the clearance. An ongoing multiphase test series is planned for testing and modifying the graphical weather system. Preliminary data shows that the nine test subjects considered the graphical presentation to be much better than their current weather information source for situation awareness, flight safety, and reroute decision making.

Scanlon, Charles H.

1992-01-01

129

Total Lightning Observations of Extreme Weather Events over the Contiguous United States  

NASA Astrophysics Data System (ADS)

The overall objective is to investigate total lightning characteristics of extreme weather events over the contiguous United States (CONUS) using TRMM (Tropical Rainfall Measuring Mission) LIS (Lightning Image Sensor) and OTD (Optical Transient Detector) satellite observations. A large LIS (10+ years) and OTD (5 years) data base is available to study the instantaneous total or cloud-to-ground (CG) plus intracloud (IC) lightning characteristics of extreme weather events. More specifically, the LIS and OTD data are combined with National Lightning Detection Network (NLDN) observations to examine the total and CG lightning flash rate and density, the IC:CG ratio, and positive CG percentage. These instantaneous lightning characteristics can be used for basic science studies to better understand the physical and dynamical linkages between lightning and precipitation and their environmental controls. They can also provide a first-look of extreme weather events leading up to future satellite observations (e.g., NOAA GOES-R Geostationary Lightning Mapper [GLM]) for use in climate studies and the short-term prediction and warning process. Extreme weather events are defined by the NOAA Storm Data reports of tornadoes, large hail (at least 0.75 inch) and strong straight-line winds (at least 50 kts). Over CONUS, there are over 70,000 severe storm reports in the TRMM spatial domain (< 35 degrees N) from 1998-2007 and over 100,000 storm reports in the OTD spatial domain (5/1995-4/2000). Temporal co-location is on the order of 1% (i.e., 1000's of coincident overpasses), providing a statistically significant sample of instantaneous total lightning properties. This instantaneous behavior of lightning in extreme weather is then compared to that of typical thunderstorm events, or randomly sampled LIS/OTD events in which the extreme events have been eliminated from the population. Results describing the instantaneous behavior of total lightning within a large sample of extreme and typical thunderstorms over CONUS will be presented. When possible, coincident VHF lightning observations from the ground-based Northern Alabama Lightning Mapping Array (LMA) are compared to the LIS/OTD optical lightning signatures, providing a validation source for instantaneous space-based optical lightning properties and a means to extend lightning inferences over the life-cycle of extreme weather.

Carey, L. D.; Petersen, W. A.; Christian, H. J.

2008-12-01

130

Planetary Space Weather: Long term prediction based on observations of hidden sunspot development  

NASA Astrophysics Data System (ADS)

Space weather phenomena at the Earth or other planets are caused by activities on the solar surface. These are accompanied by intensified Lyman alpha radiation which can be used to monitor active solar regions even when they move behind the Sun as seen from Earth. Using the Lyman alpha mapper SWAN on SOHO one can follow the development of these active regions and thereby predict their state long before they re-appear around the limb of the Sun. This information can be used to prepare for possible adverse effects on infrastructures up to 15 days before the solar wind particles start interacting with the near-Earth environment. In a similar way the space weather situation can be predicted for the environment around other planets in the Solar system.

Schmidt, W.; Quémerais, E.; Kyrölä, E.

2014-04-01

131

On the sensitivity of numerical weather prediction to remotely sensed marine surface wind data - A simulation study  

NASA Technical Reports Server (NTRS)

The reported investigation has the objective to assess the potential impact on numerical weather prediction (NWP) of remotely sensed surface wind data. Other investigations conducted with similar objectives have not been satisfactory in connection with a use of procedures providing an unrealistic distribution of initial errors. In the current study, care has been taken to duplicate the actual distribution of information in the conventional observing system, thus shifting the emphasis from accuracy of the data to the data coverage. It is pointed out that this is an important consideration in assessing satellite observing systems since experience with sounder data has shown that improvements in forecasts due to satellite-derived information is due less to a general error reduction than to the ability to fill data-sparse regions. The reported study concentrates on the evaluation of the observing system simulation experimental design and on the assessment of the potential of remotely sensed marine surface wind data.

Cane, M. A.; Cardone, V. J.; Halem, M.; Halberstam, I.

1981-01-01

132

Combining solar science and asteroid science with the space weather observation network (SWON)  

NASA Astrophysics Data System (ADS)

The peculiarity of space weather for Earth orbiting satellites, air traffic and power grids on Earth and especially the financial and operational risks posed by damage due to space weather, underline the necessity of space weather observation. The importance of such observations is even more increasing due to the impending solar maximum. In recognition of this importance we propose a mission architecture for solar observation as an alternative to already published mission plans like Solar Probe (NASA) or Solar Orbiter (ESA). Based upon a Concurrent Evaluation session in the Concurrent Engineering Facility of the German Aerospace Center, we suggest using several spacecraft in an observation network. Instead of placing such spacecraft in a solar orbit, we propose landing on several asteroids, which are in opposition to Earth during the course of the mission and thus allow observation of the Sun's far side. Observation of the far side is especially advantageous as it improves the warning time with regard to solar events by about 2 weeks. Landing on Inner Earth Object (IEO) asteroids for observation of the Sun has several benefits over traditional mission architectures. Exploiting shadowing effects of the asteroids reduces thermal stress on the spacecraft, while it is possible to approach the Sun closer than with an orbiter. The closeness to the Sun improves observation quality and solar power generation, which is intended to be achieved with a solar dynamic system. Furthermore landers can execute experiments and measurements with regard to asteroid science, further increasing the scientific output of such a mission. Placing the spacecraft in a network would also benefit the communication contact times of the network and Earth. Concluding we present a first draft of a spacecraft layout, mission objectives and requirements as well as an initial mission analysis calculation.

Maiwald, Volker; Weiß, André; Jansen, Frank

2012-12-01

133

Using MSG-SEVIRI Cloud Physical Properties and Weather Radar Observations for the Detection of Cb/TCu Clouds  

E-print Network

Using MSG-SEVIRI Cloud Physical Properties and Weather Radar Observations for the Detection of Cb (SEVIRI) on board Meteosat Second Generation (MSG) satellites and weather radar reflectivity factors/TCu clouds for the collection of pixels that pass the CCM. In this model, MSG-SEVIRI cloud physical

Schmeits, Maurice

134

Low Cloud Type over the Ocean from Surface Observations. Part I: Relationship to Surface Meteorology and the Vertical Distribution of Temperature and Moisture  

Microsoft Academic Search

Surface cloud observations and coincident surface meteorological observations and soundings from five ocean weather stations are used to establish representative relationships between low cloud type and marine boundary layer (MBL) properties for the subtropics and midlatitudes by compositing soundings and meteorological ob- servations for which the same low cloud type was observed. Physically consistent relationships are found to exist between

Joel R. Norris

1998-01-01

135

WORLD SURFACE CURRENTS FROM SHIP'S DRIFT OBSERVATIONS  

SciTech Connect

Over 4 million observations of ship's drift are on file at the U.S. National Oceanographic Data Centre, in Washington, D. C., representing a vast amount of information on ocean surface currents. The observed drift speeds are dependent on the frequency of occurence of the particular current speeds and the frequency of observation. By comparing frequency of observation with the drift speeds observed it is possible to confirm known current patterns and detect singularities in surface currents.

Duncan, C.P.; Schladow, S.G.

1980-11-01

136

Turning rock into saprolite: Linking observations and models of vadose zone dynamics and chemical weathering  

NASA Astrophysics Data System (ADS)

Chemical weathering of rock into saprolite requires contact between water and unweathered rock, which occurs frequently but discontinuously in the unsaturated zone. Saprolite is a direct precursor to mobile regolith, and the distribution and rate of saprolite development play a role in sediment production on hillslopes. We strive to understand both the timing and spatial distribution of saprolite development in the subsurface, which is controlled by the delivery of fresh water to unweathered rock. We hypothesize that climate has a strong control on delivery of water to saprolite in the vadose zone, and hence on the rate of saprolite formation. In addition, the rate of water delivery is strongly modulated by the local fracture field, lending a strong heterogeneity to water delivery and weathering rates. To test this hypothesis, we link observations of moisture content in soil and saprolite with a numerical model of vadose zone dynamics. The moisture measurements are taken in the Boulder Creek watershed in central Colorado. This 1160 km2 catchment, which is underlain by fractured crystalline rocks (mainly granodiorite), ranges in elevation from high alpine peaks at 4120 m to the Colorado piedmont at 1480 m. The complex hydrologic architecture of the unsaturated zone necessitates a model that can incorporate multiple permeabilities to represent the variable flow paths in the soil, saprolite, and fractures. Therefore, we employed VS2DI, a Richards equation-based model, on two-dimensional hillslopes to visualize flow paths in the unsaturated zone and calculate volumetric moisture content at observation points. We ran multiple simulations investigating the relative roles of fracture spacing and variable timing and intensity of precipitation. Model experiments suggest that fractures are the primary pathway for delivering water deep below the subsurface. Where fracture density is higher, more water is delivered to the deep subsurface, allowing more chemical weathering at depth. Our results also indicate that both the intensity and total magnitude of precipitation events affect the flow paths of water in the subsurface. The effects of water flux in the subsurface on chemical weathering are modeled using a linear first-order reactive-transport model for albite dissolution. This reactive-transport model reveals the importance of timing and magnitude of precipitation on chemical weathering rates, as well as the importance of fractures on the spatial distribution of weathering in the unsaturated zone. The results indicate that the development of saprolite is strongly controlled by the temporal distribution of precipitation throughout the year. Water reaches deeper into unweathered rock when precipitation is concentrated during one season rather than being evenly distributed throughout the year. This finding suggests an intriguing link between the saprolite development and changing climate in mountain environments.

Langston, A. L.; Tucker, G. E.; Anderson, R. S.; Anderson, S. P.

2011-12-01

137

Antarctic Weather  

NSDL National Science Digital Library

Visitors to this site can read a discussion about the weather in Anarctica, including why it is so cold, how weather observations are conducted there, and what role the continent plays in the global weather system. Links to related topics, a wind chill calculator, and a Fahrenheit-Celsius-Kelvin temperature converter are also provided.

138

Antarctic Weather  

NSDL National Science Digital Library

Visitors to this site can read a discussion about the weather in Antarctica, including why it is so cold, how weather observations are conducted there, and what role the continent plays in the global weather system. Links to related topics, a wind chill calculator, and a Fahrenheit-Celsius-Kelvin temperature converter are also provided.

2010-01-01

139

Surface clear-sky shortwave radiative closure intercomparisons in the Weather Research and Forecasting model  

NASA Astrophysics Data System (ADS)

The ability of the Rapid Radiative Transfer Model for GCMs (RRTMG) and Goddard shortwave (SW) radiative schemes to reproduce global (GHI), direct (DNI), and diffuse (DIF) fluxes at the surface in clear-sky conditions is examined within the Weather Research and Forecasting (WRF) modeling framework. The models were forced using measurements of precipitable water and aerosol optical properties from five AERONET sites and were evaluated against high-quality observations of GHI, DNI, and DIF at four nearby or coincident sites of the SURFRAD network and one at the Atmospheric Radiation Measurement Central Facility in the contiguous US. In addition, the performance has been intercompared against the Dudhia broadband SW parameterization together with a regressive model to calculate DNI and DIF and the top-class SMARTS2 SW spectral model. The role of aerosols has been investigated by running the models with and without aerosols. All of them have shown outstanding skill at predicting GHI within the range of the expected observational error, regardless of whether aerosol information is provided as input. When aerosol information is not provided, DNI and DIF are affected by strong biases. In contrast, providing observed aerosols as input solves the bias issue for DNI and nearly does for DIF using the RRTMG scheme. The RRTMG has also proven to have high potential skill for long-term assessment of clear-sky GHI, DNI, and DIF irradiance, as long as reliable aerosol inputs are provided. Considering its simplicity, the Dudhia scheme has also shown a remarkable ability for solar resource assessment in clear-sky conditions.

Ruiz-Arias, José A.; Dudhia, Jimy; Santos-Alamillos, Francisco J.; Pozo-Vázquez, David

2013-09-01

140

Observed change for the atmosphere and surface, and for extremes  

NASA Astrophysics Data System (ADS)

The evidence of climate change from observations of the atmosphere and surface has grown significantly during recent years. Advances in the global climate observing system (in particular using satellites and reanalyses) have contributed to improved monitoring capabilities. At the same time, new dataset developments since AR4 have improved understanding of data issues and observational uncertainties. Developing homogeneous long-term global and regional data records from different sources remains a challenge. Instrumental observations since about 1850 and satellite observations since 1979 indicate changes in atmospheric composition, radiation budgets, temperature, the hydrological cycle (including precipitation and clouds) and atmospheric circulation. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850. Confidence in precipitation change averaged over global land areas since 1901 is low prior to 1951 and medium afterwards. Changes in many extreme weather and climate events (such as cold spells, heat waves, heavy precipitation events, droughts and tropical cyclones) have been observed since about 1950, consistent with the warming. For some of these extremes, a revised global-scale assessment from previous IPCC reports is provided. Especially for extremes, assessments of recent observed changes are hampered by limited availability of long-term observations, changes in observing capabilities and practices over time, and methodological differences in the assessed studies.

Klein Tank, Albert M. G.; Rusticucci, Matilde; Hartmann, Dennis L.; Alexander, Lisa V.; Thorne, Peter W.

2014-05-01

141

Cirrus cloud diagnosis using numerical weather-prediction model and a comparison with observations  

NASA Astrophysics Data System (ADS)

Cirrus clouds in the upper troposphere and lower stratosphere (UTLS) can impact the efficiency and effectiveness of infrared directed energy (laser) applications, including laser communications systems, due to attenuation (absorption and scattering) of energy. The accurate prediction of cirrus clouds, including subvisual cirrus, is often difficult for operational numerical weather prediction (NWP) models because the models require high resolution and advanced cloud microphysics schemes. We solved the fully three-dimensional, moist, compressible, non-hydrostatic Navier-Stokes equations using a vertically-stretched adaptive grid nested within the Weather Research and Forecasting (WRF) model over a geographical region of interest. We used an adaptive time-split integration scheme for the temporal discretization. We used the Thompson cloud microphysical parameterization scheme for the cirrus cloud development. The initial conditions and boundary conditions for the WRF simulations were extracted from the European Centre for Medium Range Weather Forecasting (ECMWF) T799L91 global analyses. We ran the simulation for a domain centered on the coast of Southern California and the results are compared to meteorological satellite and radiosonde observations for selected locations.

Mahalov, A.; Lefevre, R.; Cocks, S.

2009-02-01

142

Evaluating the Impacts of NASA/SPoRT Daily Greenness Vegetation Fraction on Land Surface Model and Numerical Weather Forecasts  

NASA Technical Reports Server (NTRS)

The NASA Short-term Prediction Research and Transition (SPoRT) Center develops new products and techniques that can be used in operational meteorology. The majority of these products are derived from NASA polar-orbiting satellite imagery from the Earth Observing System (EOS) platforms. One such product is a Greenness Vegetation Fraction (GVF) dataset, which is produced from Moderate Resolution Imaging Spectroradiometer (MODIS) data aboard the NASA EOS Aqua and Terra satellites. NASA SPoRT began generating daily real-time GVF composites at 1-km resolution over the Continental United States (CONUS) on 1 June 2010. The purpose of this study is to compare the National Centers for Environmental Prediction (NCEP) climatology GVF product (currently used in operational weather models) to the SPoRT-MODIS GVF during June to October 2010. The NASA Land Information System (LIS) was employed to study the impacts of the new SPoRT-MODIS GVF dataset on land surface models apart from a full numerical weather prediction (NWP) model. For the 2010 warm season, the SPoRT GVF in the western portion of the CONUS was generally higher than the NCEP climatology. The eastern CONUS GVF had variations both above and below the climatology during the period of study. These variations in GVF led to direct impacts on the rates of heating and evaporation from the land surface. The second phase of the project is to examine the impacts of the SPoRT GVF dataset on NWP using the Weather Research and Forecasting (WRF) model. Two separate WRF model simulations were made for individual severe weather case days using the NCEP GVF (control) and SPoRT GVF (experimental), with all other model parameters remaining the same. Based on the sensitivity results in these case studies, regions with higher GVF in the SPoRT model runs had higher evapotranspiration and lower direct surface heating, which typically resulted in lower (higher) predicted 2-m temperatures (2-m dewpoint temperatures). The opposite was true for areas with lower GVF in the SPoRT model runs. These differences in the heating and evaporation rates produced subtle yet quantifiable differences in the simulated convective precipitation systems for the selected severe weather case examined.

Bell, Jordan R.; Case, Jonathan L.; Molthan, Andrew L.

2011-01-01

143

A High-Resolution 3D Weather Radar, MSG, and Lightning Sensor Observation Composite  

NASA Astrophysics Data System (ADS)

Within the research group 'Object-based Analysis and SEamless prediction' (OASE) of the Hans Ertel Centre for Weather Research programme (HerZ), a data composite containing weather radar, lightning sensor, and Meteosat Second Generation observations is being developed for the use in object-based weather analysis and nowcasting. At present, a 3D merging scheme combines measurements of the Bonn and Jülich dual polarimetric weather radar systems (data provided by the TR32 and TERENO projects) into a 3-dimensional polar-stereographic volume grid, with 500 meters horizontal, and 250 meters vertical resolution. The merging takes into account and compensates for various observational error sources, such as attenuation through hydrometeors, beam blockage through topography and buildings, minimum detectable signal as a function of noise threshold, non-hydrometeor echos like insects, and interference from other radar systems. In addition to this, the effect of convection during the radar 5-minute volume scan pattern is mitigated through calculation of advection vectors from subsequent scans and their use for advection correction when projecting the measurements into space for any desired timestamp. The Meteosat Second Generation rapid scan service provides a scan in 12 spectral visual and infrared wavelengths every 5 minutes over Germany and Europe. These scans, together with the derived microphysical cloud parameters, are projected into the same polar stereographic grid used for the radar data. Lightning counts from the LINET lightning sensor network are also provided for every 2D grid pixel. The combined 3D radar and 2D MSG/LINET data is stored in a fully documented netCDF file for every 5 minute interval, and is made ready for tracking and object based weather analysis. At the moment, the 3D data only covers the Bonn and Jülich area, but the algorithms are planed to be adapted to the newly conceived DWD polarimetric C-Band 5 minute interval volume scan strategy. An extension of the 3D composite to all of Germany is therefore possible and set as a goal.

Diederich, Malte; Senf, Fabian; Wapler, Kathrin; Simmer, Clemens

2013-04-01

144

Space Weathering Impact on Solar System Surfaces - Community White Paper for Planetary Science Decadal Survey 2009 - 2011  

Microsoft Academic Search

Universal processes of space weathering within and beyond the solar system include plasma ion implantation into surfaces, surface sputtering by plasma and energetic ions, surface volume ionization by penetrating charged particles, and radiolytic chemistry evolved from radiation products. Surface regolith layers on bodies with very thin or no significant atmospheres evolve structurally and chemically from impact processing by micrometeroids and

Kurt D. Retherford; J. F. Cooper; C. Paranicas; R. E. Johnson; E. C. Sittler; R. E. Hartle; M. A. McGrath; D. Pascu

2009-01-01

145

An observed database to characterize the weather conditions associated with subtropical cyclogenesis over southern-southeastern Brazil  

NASA Astrophysics Data System (ADS)

A project to study the climatic, dynamic and synoptic aspects of subtropical cyclones that develop in southern-southeastern coast of Brazil is in development. The weather conditions associated with such cyclones is an important question that must be answered in this project. However, for such characterization it is necessary to use the local meteorological observations of wind, wind gust, rainfall, air temperature, etc. The NCEP (National Center for Environmental Prediction) reanalysis have spatial and time resolutions that provide elements to study the synoptic and dynamics of meteorological events (cyclone, anticyclones, troughs, ridges, monsoons circulations, etc) until the production of complex climatology. However, this analysis has coarse horizontal resolution (~250 Km) that often does not allow the identification of intense meteorological phenomena. A more precise characterization of location and intensity of weather conditions associated with subtropical cyclones would be performed using local observations. Therefore, this work describes the methodology to construct a database of surface weather observations using a relational database management system (RDBMS) MySQL. The data source are SYNOP (Surface Synoptic Observations), METAR (Meteorological Aerodrome Report), NCDC (National Climatic Data Center) and CETESB (Environmental Agency of Sao Paulo State) that are available online through dynamic web page. An iterative algorithm robot was developed to automate the data extraction. Most of the data source are encoded or at non-standard format, hence was developed an algorithm in C++, using the REGEX library, an engine of text pattern search, for decode and handle the exception (erroneous and corrupted data). After the data decoding and formatting it is stored into the MySQL database. The structure of database was divided into categories of tables: a table with the source of data definition, a table with stations information and two sets of tables (for hourly and daily data) for each variable (temperature, pressure, wind, rain, etc). The data in NCDC, SYNOP, METAR, and CETESB are available from 1942, 1999, 1997 and 1997, respectively. The work was extended to a data set that included the entire Latin America using the MySQL that give us a simple and versatile platform allowing the continued growth of the database. The next step is to establish a web interface to make the data available to general public.

Yamamoto, R.; Porfirio da Rocha, R.

2012-04-01

146

Widespread surface weathering on early Mars: A case for a warmer and wetter climate  

NASA Astrophysics Data System (ADS)

Early Mars (>3 Ga) underwent aqueous alteration as evidenced by fluvial/lacustrine morphologies and the recent discovery of widespread hydrous clays. Despite compelling evidence for diverse and localized aqueous environments, the possibility for sustained liquid water globally on the martian surface and over geological timescales is still highly debated. Instead, a durably cold and dry Mars scenario is often proposed. By studying specific Fe/Mg and Al-rich clay stratigraphies on Mars by means of a planetary scale orbital investigation, we present new evidence that Mars experienced an early era (>3.7 Ga) of widespread aqueous alteration consistent with surface weathering.

Carter, John; Loizeau, Damien; Mangold, Nicolas; Poulet, François; Bibring, Jean-Pierre

2015-03-01

147

A much warmer Earth surface for most of geologic time: implications to biotic weathering  

NASA Technical Reports Server (NTRS)

The authors present two scenarios for the temperature history of Earth. One scenario is conventional, the other relies on a warmer history. Both scenarios include surface cooling determined by the evolution of the biosphere and are similar until the Proterozoic period. The warmer scenario requires a higher plant/lichen terrestrial biota to increase weathering intensity. Justification for a warmer surface includes period temperatures from the oxygen isotope record of coexisting phosphates and cherts, an upper limit of 58 degrees C from primary gypsum precipitation, and the lack of fractionation of sulfur isotopes between sulfide and sulfates in Archean sediments.

Schwartzman, D. W.; McMenamin, M.

1993-01-01

148

State of Art in space weather observational activities and data management in Europe  

NASA Astrophysics Data System (ADS)

One of the primary scientific and technical goals of space weather is to produce data in order to investigate the Sun impact on the Earth and its environment. Studies based on data mining philosophy yield increase the knowledge of space weather physical properties, modelling capabilities and gain applications of various procedures in space weather monitoring and forecasting. Exchanging tailored individually and/or jointly data between different entities, storing of the databases and making data accessible for the users is the most important task undertaken by investigators. National activities spread over Europe is currently consolidated pursuant to the terms of effectiveness and individual contributions embedded in joint integrated efforts. The role of COST 724 Action in animation of such a movement is essential. The paper focuses on the analysis of the European availability in the Internet near-real time and historical collections of the European ground based and satellite observations, operational indices and parameters. A detailed description of data delivered is included. The structure of the content is supplied according to the following selection: (1) observations, raw and/or corrected, updated data, (2) resolution, availability of real-time and historical data, (3) products, as the results of models and theory including (a) maps, forecasts and alerts, (b) resolution, availability of real-time and historical data, (4) platforms to deliver data. Characterization of the networking of stations, observatories and space related monitoring systems of data collections is integrated part of the paper. According to these provisions operational systems developed for these purposes is presented and analysed. It concerns measurements, observations and parameters from the theory and models referred to local, regional collections, European and worldwide networks. Techniques used by these organizations to generate the digital content are identified. As the reference pan-European and some national data centres and bases are described and compared with currently available data information provided worldwide and by relevant entities outside Europe. Current, follow up and expected future European space weather observational activities and data management perspectives in respect to European main lines of policy is the subject of the conclusions.

Stanislawska, Iwona

149

Data Assimilation of SMAP Observations and the Impact on Weather Forecasts and Heat Stress  

NASA Technical Reports Server (NTRS)

SPoRT produces real-time LIS soil moisture products for situational awareness and local numerical weather prediction over CONUS, Mesoamerica, and East Africa ?Currently interact/collaborate with operational partners on evaluation of soil moisture products ?Drought/fire ?Extreme heat ?Convective initiation ?Flood and water borne diseases ?Initial efforts to assimilate L2 soil moisture observations from SMOS (as a precursor for SMAP) have been successful ?Active/passive blended product from SMAP will be assimilated similarly and higher spatial resolution should improve on local-scale processes

Zavodsky, Bradley; Case, Jonathan; Blankenship, Clay; Crosson, William; White, Khristopher

2014-01-01

150

On the dynamic estimation of relative weights for observation and forecast in numerical weather prediction  

NASA Technical Reports Server (NTRS)

The problem of merging direct and remotely sensed (indirect) data with forecast data to get an estimate of the present state of the atmosphere for the purpose of numerical weather prediction is examined. To carry out this merging optimally, it is necessary to provide an estimate of the relative weights to be given to the observations and forecast. It is possible to do this dynamically from the information to be merged, if the correlation structure of the errors from the various sources is sufficiently different. Some new statistical approaches to doing this are described, and conditions quantified in which such estimates are likely to be good.

Wahba, Grace; Deepak, A. (editor)

1988-01-01

151

Winter Weather  

MedlinePLUS

... weather presents hazards including slippery roads/surfaces, strong winds and environmental cold. Employers must prevent illnesses, injuries, ... from surfaces) Use extreme caution when working near power lines Prevent harmful exposure to cold temperatures and ...

152

Space Weather Observations by GNSS Radio Occultation: From FORMOSAT-3/COSMIC to FORMOSAT-7/COSMIC-2  

NASA Astrophysics Data System (ADS)

The joint Taiwan-United States FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission, hereafter called COSMIC, is the first satellite constellation dedicated to remotely sense Earth's atmosphere and ionosphere using a technique called Global Positioning System (GPS) radio occultation (RO). The occultations yield abundant information about neutral atmospheric temperature and moisture as well as space weather estimates of slant total electron content, electron density profiles, and an amplitude scintillation index, S4. With the success of COSMIC, the United States and Taiwan are moving forward with a follow-on RO mission named FORMOSAT-7/COSMIC-2 (COSMIC-2), which will ultimately place 12 satellites in orbit with two launches in 2016 and 2019. COSMIC-2 satellites will carry an advanced Global Navigation Satellite System (GNSS) RO receiver that will track both GPS and Russian Global Navigation Satellite System signals, with capability for eventually tracking other GNSS signals from the Chinese BeiDou and European Galileo system, as well as secondary space weather payloads to measure low-latitude plasma drifts and scintillation at multiple frequencies. COSMIC-2 will provide 4-6 times (10-15X in the low latitudes) the number of atmospheric and ionospheric observations that were tracked with COSMIC and will also improve the quality of the observations. In this article we focus on COSMIC/COSMIC-2 measurements of key ionospheric parameters.

Yue, Xinan; Schreiner, William S.; Pedatella, Nicholas; Anthes, Richard A.; Mannucci, Anthony J.; Straus, Paul R.; Liu, Jann-Yenq

2014-11-01

153

The land surface-atmosphere interaction: A review based on observational and global modeling perspectives  

Microsoft Academic Search

This review discusses the land-surface-atmosphere interaction using observations from two North American field experiments (First International Satellite Land Surface Climatology Project Field Experiment (FIFE) and Boreal Ecosystem Atmosphere Study (BOREAS)) and the application of research data to the improvement of land surface and boundary layer parameterizations in the European Centre for Medium-Range Weather Forecast (ECMWF) global forecast model. Using field

Alan K. Betts; John H. Ball; Anton C. M. Beljaars; Martin J. Miller; Pedro A. Viterbo

1996-01-01

154

Assessing the Impact of Observations on Numerical Weather Forecasts Using the Adjoint Method  

NASA Technical Reports Server (NTRS)

The adjoint of a data assimilation system provides a flexible and efficient tool for estimating observation impacts on short-range weather forecasts. The impacts of any or all observations can be estimated simultaneously based on a single execution of the adjoint system. The results can be easily aggregated according to data type, location, channel, etc., making this technique especially attractive for examining the impacts of new hyper-spectral satellite instruments and for conducting regular, even near-real time, monitoring of the entire observing system. This talk provides a general overview of the adjoint method, including the theoretical basis and practical implementation of the technique. Results are presented from the adjoint-based observation impact monitoring tool in NASA's GEOS-5 global atmospheric data assimilation and forecast system. When performed in conjunction with standard observing system experiments (OSEs), the adjoint results reveal both redundancies and dependencies between observing system impacts as observations are added or removed from the assimilation system. Understanding these dependencies may be important for optimizing the use of the current observational network and defining requirements for future observing systems

Gelaro, Ronald

2012-01-01

155

Surface degradation of CeO2 stabilized acrylic polyurethane coated thermally treated jack pine during accelerated weathering  

NASA Astrophysics Data System (ADS)

The thermally treated wood is a new value-added product and is very important for the diversification of forestry products. It drew the attention of consumers due to its attractive dark brown color. However, it loses its color when exposed to outside environment. Therefore, development of a protective coating for this value added product is necessary. In the present study, the efficiency of CeO2 nano particles alone or in combination with lignin stabilizer and/or bark extracts in acrylic polyurethane polymer was investigated by performing an accelerated weathering test. The color measurement results after accelerated weathering demonstrated that the coating containing CeO2 nano particles was the most effective whereas visual assessment suggested the coating containing CeO2 nano particles and lignin stabilizer as the most effective coating. The surface polarity changed for all the coatings during weathering and increase in contact angle after weathering suggested cross linking and reorientation of the polymer chain during weathering. The surface chemistry altered during weathering was evaluated by ATR-FTIR analysis. It suggested formation of different carbonyl byproducts during weathering. The chain scission reactions of the urethane linkages were not found to be significant during weathering.

Saha, Sudeshna; Kocaefe, Duygu; Boluk, Yaman; Pichette, Andre

2013-07-01

156

Biochemical evolution II: Origin of life in tubular microstructures on weathered feldspar surfaces  

PubMed Central

Mineral surfaces were important during the emergence of life on Earth because the assembly of the necessary complex biomolecules by random collisions in dilute aqueous solutions is implausible. Most silicate mineral surfaces are hydrophilic and organophobic and unsuitable for catalytic reactions, but some silica-rich surfaces of partly dealuminated feldspars and zeolites are organophilic and potentially catalytic. Weathered alkali feldspar crystals from granitic rocks at Shap, north west England, contain abundant tubular etch pits, typically 0.4–0.6 ?m wide, forming an orthogonal honeycomb network in a surface zone 50 ?m thick, with 2–3 × 106 intersections per mm2 of crystal surface. Surviving metamorphic rocks demonstrate that granites and acidic surface water were present on the Earth’s surface by ?3.8 Ga. By analogy with Shap granite, honeycombed feldspar has considerable potential as a natural catalytic surface for the start of biochemical evolution. Biomolecules should have become available by catalysis of amino acids, etc. The honeycomb would have provided access to various mineral inclusions in the feldspar, particularly apatite and oxides, which contain phosphorus and transition metals necessary for energetic life. The organized environment would have protected complex molecules from dispersion into dilute solutions, from hydrolysis, and from UV radiation. Sub-micrometer tubes in the honeycomb might have acted as rudimentary cell walls for proto-organisms, which ultimately evolved a lipid lid giving further shelter from the hostile outside environment. A lid would finally have become a complete cell wall permitting detachment and flotation in primordial “soup.” Etch features on weathered alkali feldspar from Shap match the shape of overlying soil bacteria. PMID:9860941

Parsons, Ian; Lee, Martin R.; Smith, Joseph V.

1998-01-01

157

Modeling COSMO-SkyMed measurements of precipitating clouds over the sea using simultaneous weather radar observations  

NASA Astrophysics Data System (ADS)

Several satellite missions employing X-band synthetic aperture radar (SAR) have been activated to provide high-resolution images of normalized radar cross-sections (NRCS) on land and ocean for numerous applications. Rainfall and wind affect the sea surface roughness and consequently the NRCS from the combined effects of corrugation due to impinging raindrops and surface wind. X-band frequencies are sensitive to precipitation: intense convective cells result in irregularly bright and dark patches in SAR images, masking changes in surface NRCS. Several works have modeled SAR images of intense precipitation over land; less adequately investigated is the precipitation effect over the sea surface. These images are analyzed in this study by modeling both the scattering and attenuation of radiation by hydrometeors in the rain cells and the NRCS surface changes using weather radar precipitation estimates as input. The reconstruction of X-band SAR returns in precipitating clouds is obtained by the joint utilization of volume reflectivity and attenuation, the latter estimated by coupling ground-based radar measurements and an electromagnetic model to predict the sea surface NRCS. Radar signatures of rain cells were investigated using X-band SAR images collected from the COSMO-SkyMed constellation of the Italian Space Agency. Two case studies were analyzed. The first occurred over the sea off the coast of Louisiana (USA) in summer 2010 with COSMO-SkyMed (CSK®) ScanSar mode monitoring of the Deepwater Horizon oil spill. Simultaneously, the NEXRAD S-band Doppler radar (KLIX) located in New Orleans was scanning the same portion of ocean. The second case study occurred in Liguria (Italy) on November 4, 2011, during an extraordinary flood event. The same events were observed by the Bric della Croce C-band dual polarization radar located close to Turin (Italy). The polarimetric capability of the ground radars utilized allows discrimination of the composition of the precipitation volume, in particular distinguishing ice from rain. Results shows that for space-borne SAR at X-band, effects due to precipitation on water surfaces can be modeled using coincident ground-based weather radar measurements.

Roberto, N.; Baldini, L.; Facheris, L.; Chandrasekar, V.

2014-07-01

158

Micro-mapping Meteorite Surfaces on Mars using Microscopic Imager Mosaics — A Tool for Unraveling Weathering History at Meridiani Planum  

NASA Astrophysics Data System (ADS)

Meteorites found on Mars provide valuable insights into martian surface processes. During the course of Mars Exploration Rover (MER) extended missions, Spirit and Opportunity have identified 17 confirmed and candidate meteorites on Mars, most of which are irons. The iron meteorites exhibit morphologies and coatings that communicate complex post-fall exposure histories relevant to an understanding of climate near the martian equator [1-4]. Both chemical and mechanical weathering effects are represented. Among the more significant of these are: 1) cm-scale hollowing, 2) surficial rounding, 3) mass excavation/dissolution and removal, 4) differential etching of kamacite plates and taenite lamellae, revealing Widmanstätten patterns, 5) discontinuous iron oxide coatings, and 6) the effects of cavernous weathering, which often penetrate to rock interiors. Determining the nature, magnitude, and timing of each process and its associated features is a complex problem that will be aided by laboratory experiments, image processing, and careful surface evaluation. Because some features appear to superpose others in ways analogous to stratigraphic relationships, Microscopic Imager (MI) mosaics are useful for sketching "geologic maps" of meteorite surfaces. Employing the techniques of conventional planetary mapping [5], each map was drafted manually using full-resolution MI mosaics and Adobe Photoshop software. Units were selected to represent the oxide coating, dust-coated surfaces, sand-coated surfaces, taenite lamellae, and uncoated metal. Also included are areas in shadow, and regions of blooming caused by specular reflection of metal. Regmaglypt rim crests are presented as lineations. As with stratigraphic relationships, noting embayments and other cross-cutting relationships assists with establishing the relative timing for observed weathering effects. In addition to suggesting alternating sequences of wind and water exposure [1], patterns in oxide coating occurrence show evidence that coating deposition (interpreted as a result of water interaction) was geologically recent: Because the margins of many oxide coating deposits are concentric to and slightly removed from regmaglypt rim crests, the latest cycle is interpreted as a time of coating removal, not deposition, with these topographic high points representing zones of greatest erosional attack. Assuming the oxide coating has a low to moderate hardness, this observation implies relative geologic youth for the coating. However, it is unknown whether oxide deposits are stable or actively eroded by free basaltic sand grains [e.g., 6] in the modern epoch. The high science return from ongoing meteorite studies at MER landing sites supports their consideration if meteorites are also encountered by the Mars Science Laboratory Curiosity rover in Gale Crater.

Ashley, J. W.; Herkenhoff, K. E.; Golombek, M. P.; Johnson, J. R.

2012-12-01

159

Reprinted from: Proceedings, International Workshop on Observations/Forecasting of Meso-scale Severe Weather and  

E-print Network

-scale Severe Weather and Technology of Reduction of Relevant Disasters (Tokyo, Japan), 22-26 February 1993, 181 on the ingredients for particular severe weather events, a focus is provided for the forecasting process of forecasters is discussed also, as a necessary component in a balanced approach to weather forecasting

Doswell III, Charles A.

160

Accurately Estimating the State of a Geophysical System with Sparse Observations: Predicting the Weather  

E-print Network

Utilizing the information in observations of a complex system to make accurate predictions through a quantitative model when observations are completed at time $T$, requires an accurate estimate of the full state of the model at time $T$. When the number of measurements $L$ at each observation time within the observation window is larger than a sufficient minimum value $L_s$, the impediments in the estimation procedure are removed. As the number of available observations is typically such that $L \\ll L_s$, additional information from the observations must be presented to the model. We show how, using the time delays of the measurements at each observation time, one can augment the information transferred from the data to the model, removing the impediments to accurate estimation and permitting dependable prediction. We do this in a core geophysical fluid dynamics model, the shallow water equations, at the heart of numerical weather prediction. The method is quite general, however, and can be utilized in the analysis of a broad spectrum of complex systems where measurements are sparse. When the model of the complex system has errors, the method still enables accurate estimation of the state of the model and thus evaluation of the model errors in a manner separated from uncertainties in the data assimilation procedure.

Zhe An; Daniel Rey; Henry D. I. Abarbanel

2014-05-11

161

Severe Weather  

NSDL National Science Digital Library

Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. The National Weather Service (NWS)--which is part of NOAA and its parent agency, the Department of Commerce--is charged with the critical responsibility of observing and reporting the weather and with issuing forecasts and warnings of weather and floods in the interest of national safety and economy. Through a massive network of weather-monitoring and reporting stations around the globe, including land, sea, air, and space-borne instruments, NWS scientists constantly assimilate all of the reliable weather data available. Much of this data are then used in numerical computer models of the atmosphere that help to accurately describe and interpret current conditions and produce the best possible forecasts of future weather.

Evan B. Forde

2004-04-01

162

Weatherability Evaluation of Nanocomposite Polymeric Treatments for Surface Protection of Construction Materials  

SciTech Connect

In this work the protective efficacy and stability against UV weathering of polymeric nanocomposites for concrete (CLS) surface protection have been evaluated. In particular, nanocomposite hybrids were prepared dispersing a commercial organomodified montmorillonite (Cloisite 30B) in two different polymeric matrices, one based on fluoroelastomers (Fluoline CP), the other on silane and siloxane (Antipluviol S). The obtained systems were characterized by several techniques (SAXD, DSC, TGA, FT-IR, contact angle measurements, colorimetry), before and after accelerated aging due to UV exposure, in order to evaluate the effect of the nanoscale dispersion of the organoclay on the properties and the UV stability of the treatments.

Scarfato, Paola; Letizia Fariello, Maria; Di Maio, Luciano; Incarnato, Loredana [University of Salerno, Department of Chemical and Food Engineering, Via Ponte don Melillo, 84084 Fisciano (Italy)] [Research Centre NANO lowbar MATES, University of Salerno, Via Ponte don Melillo, 84084 Fisciano (Italy)

2010-06-02

163

Surface degradation of polymer insulators under accelerated climatic aging in weather-ometer  

SciTech Connect

Climatic aging experiments were conducted on two types of outdoor polymer insulators by using a programmable weather-ometer. The housing materials for the insulators were silicone rubber (SR) and ethylene propylene diene monomer (EPDM). The accelerated aging stresses were comprised of ultraviolet radiation, elevated temperature, temperature cycling, thermal shock and high humidity. Their effects on the insulator surface conditions and electrical performance wee examined through visual inspection and SEM studies, contact angle measurements, thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS) analysis, and 50% impulse flashover voltage tests. The results showed a significant damage on the insulator surface caused by some of the imposed aging stresses. The EDS analysis suggested a photooxidation process that happened on the insulator surface during the aging period.

Xu, G.; McGrath, P.B. [Clarkson Univ., Potsdam, NY (United States). Electrical and computer Engineering Dept.; Burns, C.W. [Niagara Mohawk Power Corp., Syracuse, NY (United States). Research and Development Dept.

1996-12-31

164

Low Cloud Type over the Ocean from Surface Observations. Part III: Relationship to Vertical Motion and the Regional Surface Synoptic Environment  

Microsoft Academic Search

Composite large-scale dynamical fields contemporaneous with low cloud types observed at midlatitude Ocean Weather Station (OWS) C and eastern subtropical OWS N are used to establish representative relationships between low cloud type and the synoptic environment. The composites are constructed by averaging meteo- rological observations of surface wind and sea level pressure from volunteering observing ships (VOS) and analyses of

Joel R. Norris; Stephen A. Klein

2000-01-01

165

Observing System Simulation Experiments to evaluate the potential impact of alternative technologies for space-based lidar winds on numerical weather prediction (Invited)  

NASA Astrophysics Data System (ADS)

Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. Extensive OSSEs have been conducted at NASA/ GSFC and NOAA/AOML in collaboration with Simpson Weather Associates and operational data assimilation centers from 1985-2005. As described below, these OSSEs determined correctly the quantitative potential for several proposed satellite observing systems to improve weather analysis and prediction prior to their launch, evaluated trade-offs in orbits, coverage and accuracy for space-based wind lidars, and were used in the development of the methodology that led to the first beneficial impacts of satellite surface winds on numerical weather prediction. More recent OSSEs have continued to demonstrate potential for a space-based wind lidar to improve atmospheric analyses and forecasts, especially in the tropics. In this paper, we will report on new OSSEs designed to assess the potential impact of different lidar technologies.

Atlas, R. M.; Emmitt, G. D.; Tucker, S.; Riishojgaard, L.

2013-12-01

166

A twenty-first century California observing network for monitoring extreme weather events  

USGS Publications Warehouse

During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. In order to improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, is required. Here we describe how California is addressing their most important and costliest environmental issue – water management – in part, by installing a state-of-the-art observing system to better track the area’s most severe wintertime storms.

White, A.B.; Anderson, M.L.; Dettinger, M.D.; Ralph, F.M.; Hinojosa, A.; Cayan, D.R.; Hartman, R.K.; Reynolds, D.W.; Johnson, L.E.; Schneider, T.L.; Cifelli, R.; Toth, Z.; Gutman, S.I.; King, C.W.; Gehrke, F.; Johnston, P.E.; Walls, C.; Mann, D.; Gottas, D.J.; Coleman, T.

2013-01-01

167

Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition  

NASA Technical Reports Server (NTRS)

Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

Zhang, Shouliang; Keller, Lindsay P.

2011-01-01

168

Venus surface mineralogy - Observational and theoretical constraints  

NASA Technical Reports Server (NTRS)

Earth-based, earth-orbital, and spacecraft observations of the atmosphere and surface of Venus, thermodynamic models of atmosphere-lithosphere interactions, and where available kinetic data on relevant gas-solid reactions to place constraints on the mineralogy of the surface of Venus are used. Which minerals and mineral assemblages are stable on the surface of Venus and which, if any, of these minerals are involved in controlling the abundances of reactive gases in the atmosphere of Venus. It is concluded by identifying key issues facing us today about the mineralogy and geochemistry of the surface of Venus and suggest experimental, observational, and theoretical studies that can improve knowledge of these important questions are discussed.

Fegley, Bruce, Jr.; Treiman, Allan H.; Sharpton, Virgil L.

1992-01-01

169

Statistical relationship between surface PM10 concentration and aerosol optical depth over the Sahel as a function of weather type, using neural network methodology  

NASA Astrophysics Data System (ADS)

work aims at assessing the capability of passive remote-sensed measurements such as aerosol optical depth (AOD) to monitor the surface dust concentration during the dry season in the Sahel region (West Africa). We processed continuous measurements of AODs and surface concentrations for the period (2006-2010) in Banizoumbou (Niger) and Cinzana (Mali). In order to account for the influence of meteorological condition on the relationship between PM10 surface concentration and AOD, we decomposed the mesoscale meteorological fields surrounding the stations into five weather types having similar 3-dimensional atmospheric characteristics. This classification was obtained by a clustering method based on nonlinear artificial neural networks, the so-called self-organizing map. The weather types were identified by processing tridimensional fields of meridional and zonal winds and air temperature obtained from European Centre for Medium-Range Weather Forecasts (ECMWF) model output centered on each measurement station. Five similar weather types have been identified at the two stations. Three of them are associated with the Harmattan flux; the other two correspond to northward inflow of the monsoon flow at the beginning or the end of the dry season. An improved relationship has been found between the surface PM10 concentrations and the AOD by using a dedicated statistical relationship for each weather type. The performances of the statistical inversion computed on the test data sets show satisfactory skills for most of the classes, much better than a linear regression. This should permit the inversion of the mineral dust concentration from AODs derived from satellite observations over the Sahel.

Yahi, H.; Marticorena, B.; Thiria, S.; Chatenet, B.; Schmechtig, C.; Rajot, J. L.; Crepon, M.

2013-12-01

170

IDENTIFYING THE ROTATION RATE AND THE PRESENCE OF DYNAMIC WEATHER ON EXTRASOLAR EARTH-LIKE PLANETS FROM PHOTOMETRIC OBSERVATIONS  

E-print Network

IDENTIFYING THE ROTATION RATE AND THE PRESENCE OF DYNAMIC WEATHER ON EXTRASOLAR EARTH-LIKE PLANETS of hundreds of extrasolar planets, the search for planets like Earth and life in the uni- verse is quickly rocky planets, but they would not be able to spatially resolve a planet's surface. Using reflectance

Seager, Sara

171

SURFACE MATERIAL ANALYSIS OF S-TYPE ASTEROIDS: REMOVING THE SPACE WEATHERING EFFECT FROM REFLECTANCE SPECTRUM. Y. Ueda1  

E-print Network

SURFACE MATERIAL ANALYSIS OF S-TYPE ASTEROIDS: REMOVING THE SPACE WEATHERING EFFECT FROM of asteroid reflectance spec- tra in the UV, visible to NIR at wavelength region [e.g., 1-4]. Reflectance spectroscopy of asteroid at this range should bring us a lot of information about its surface materials

Hiroi, Takahiro

172

Space Weather Monitoring for ISS Space Environments Engineering and Crew Auroral Observations  

NASA Technical Reports Server (NTRS)

The awareness of potentially significant impacts of space weather on spaceand ground ]based technological systems has generated a strong desire in many sectors of government and industry to effectively transform knowledge and understanding of the variable space environment into useful tools and applications for use by those entities responsible for systems that may be vulnerable to space weather impacts. Essentially, effectively transitioning science knowledge to useful applications relevant to space weather has become important. This talk will present proven methodologies that have been demonstrated to be effective, and how in the current environment those can be applied to space weather transition efforts.

Minow, Joseph I.; Pettit, Donald R.; Hartman, William A.

2012-01-01

173

The Modulation of Potential Vorticity Streamers and Surface Weather Patterns by the Madden Julian Oscillation  

NASA Astrophysics Data System (ADS)

The Madden Julian Oscillation (MJO), a large-scale coupled pattern between tropical deep convection and atmospheric circulation, is known to be the dominant source of intraseasonal variability in the tropics. Its impacts, however, are not limited to tropical regions: latent heat release associated with MJO convection can force planetary scale Rossby wave trains that propagate over the globe. On the synoptic scale, propagating Rossby wave trains can culminate in Rossby wave breaking, a process that generates so-called potential vorticity (PV) streamers. PV streamers have been linked to positive upper-level PV anomalies that can influence surface weather, extreme precipitation events and the enhanced exchange between the stratosphere and troposphere. The primary goal of the present study is to investigate the possible relationship between the MJO and PV streamers. Ten MJO indices (representing MJO activity at ten specific tropical longitudes) have been obtained from the Climate Prediction Center for the boreal winter between 1978 and 2001. The data are subsequently separated into terciles (allowing for the designation of convectively active and suppressed periods of the MJO) and compared with a unique PV streamer dataset that has been previously computed from ECMWF Re-analysis data (ERA-40). The streamer dataset allows for the dynamically useful separation of streamers into cyclonically and anticyclonically breaking waves, referred to as LC2 and LC1 streamers, respectively. Statistically significant differences are found regarding the amount, location and type of PV streamers during different phases of the MJO. When the MJO is convectively active over the Indian Ocean and Indonesia, the North Central Pacific is dominated by a positive 500 hPa height anomaly, a co-located reduction in LC2 streamers and increased LC1 streamers to the south and southeast. As the convection enters the Western Pacific warm pool and approaches the international dateline, a distinct regime shift occurs: over an approximately 10-15 day period, a negative 500 hPa height anomaly forms, supplanting the previous positive anomaly. Subsequent to this time, the negative height anomaly strengthens and there is a significant increase (decrease) in LC1 (LC2) streamers. To illustrate the connection between the MJO, Rossby wave breaking and surface weather in the extratropics, a comparison between PV streamers and surface cyclone frequency (also computed from ERA-40 data; see Wernli et al. 2006) is made. A fairly good agreement between LC2 streamer and surface cyclone frequency anomalies throughout the life cycle of the MJO is found in the North Pacific basin, further highlighting the ability of organized tropical convection to modulate extratropical weather.

Moore, R.; Martius, O.

2007-12-01

174

Space Weather Measurements from the Surface of Mars with the RAD Instrument on the Mars Science Laboratory  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) is a compact, lightweight energetic particle analyzer currently operating on the surface of Mars as part of the Mars Science Laboratory (MSL) Mission. These are the first measurements of the radiation environment on the surface of another planet, and specifically Mars. RAD is providing synoptic measurements of GCR & SEP at a 2nd location in heliosphere (other than near-Earth or L1), and will aid heliospheric modeling over solar cycle. These observations of SEP fluxes will contribute to a SEP event database at Mars and Martian surface to aid prediction of Solar Energetic Particle (SEP) Events, including onset, temporal & size predictions. This presentation will provide an overview of the RAD investigation and present the early measurements of the radiation environment on the surface of Mars and discuss the importance of providing broad heliospheric coverage and situational awareness of space weather as we plan to send humans out into deep space and to Mars. RAD is supported by NASA (HEOMD) under JPL subcontract #1273039 to SwRI, and by DLR in Germany under contract with Christian-Albrechts-Universitat (CAU).

Hassler, D.; Zeitlin, C. J.; Wimmer-Schweingruber, R.; Mars Science Laboratory Science Team

2013-05-01

175

Monitoring ionospheric plasmas in space weather context via DSLP observations on board Proba-2  

NASA Astrophysics Data System (ADS)

The experiment Dual Segmented Langmuir Probe (DSLP) on board Proba-2 spacecraft (ESA) provides a long-term continual survey of basic plasma properties measured in situ in the dawn and dusk sectors of the upper terrestrial ionosphere. DSLP observations are acquired by two identical segmented spherical Langmuir probes representing a novel approach to a well developed plasma diagnostic technique. Starting its nominal operations in May 2010 almost four years of regular observations are currently being available providing a substantial data set for monitoring observed ionospheric disturbances and irregularities in view of potential space weather drivers. Here we present initial DSLP data scientific applications including seasonal or immediate variations of derived plasma properties in comparison with possible effects of sudden solar events or long term trends in the overall solar activity. In addition we present an on-line data archive build on complete DSLP data set where all raw measurements are routinely being processed into calibrated higher level data products derived from the PDS and CDF standards and made available throughout web interface.

Travnicek, Pavel; Stverak, Stepan; Hercik, David; Pavelka, Roman

2014-05-01

176

Weather Instruments.  

ERIC Educational Resources Information Center

This booklet presents some activities to measure various weather phenomena. Directions for constructing a weather station are included. Instruments including rain gauges, thermometers, wind vanes, wind speed devices, humidity devices, barometers, atmospheric observations, a dustfall jar, sticky-tape can, detection of gases in the air, and pH of…

Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

177

Weather Forecasting  

NSDL National Science Digital Library

This activity (on page 2 of the PDF) is a full inquiry investigation into meteorology and forecasting. Learners will research weather folklore, specifically looking for old-fashioned ways of predicting the weather. Then, they'll record observations of these predictors along with readings from their own homemade barometer, graphing the correct predictions for analysis. Relates to linked video, DragonflyTV: Forecasting.

Twin Cities Public Television, Inc.

2005-01-01

178

A systematic review and meta-analysis of the effects of extreme weather events and other weather-related variables on Cryptosporidium and Giardia in fresh surface waters.  

PubMed

Global climate change is expected to impact drinking water quality through multiple weather-related phenomena. We conducted a systematic review and meta-analysis of the relationship between various weather-related variables and the occurrence and concentration of Cryptosporidium and Giardia in fresh surface waters. We implemented a comprehensive search in four databases, screened 1,228 unique citations for relevance, extracted data from 107 relevant articles, and conducted random-effects meta-analysis on 16 key relationships. The average odds of identifying Cryptosporidium oocysts and Giardia cysts in fresh surface waters was 2.61 (95% CI = 1.63-4.21; I(2) = 16%) and 2.87 (95% CI = 1.76-4.67; I(2) = 0%) times higher, respectively, during and after extreme weather events compared to baseline conditions. Similarly, the average concentration of Cryptosporidium and Giardia identified under these conditions was also higher, by approximately 4.38 oocysts/100 L (95% CI = 2.01-9.54; I(2) = 0%) and 2.68 cysts/100 L (95% CI = 1.08-6.55; I(2) = 48%). Correlation relationships between other weather-related parameters and the density of these pathogens were frequently heterogeneous and indicated low to moderate effects. Meta-regression analyses identified different study-level factors that influenced the variability in these relationships. The results can be used as direct inputs for quantitative microbial risk assessment. Future research is warranted to investigate these effects and potential mitigation strategies in different settings and contexts. PMID:25719461

Young, Ian; Smith, Ben A; Fazil, Aamir

2015-03-01

179

Anti-weathering treatments to protect mineral surfaces: Hybrid sol-gel and biomimetic strategies  

NASA Astrophysics Data System (ADS)

The natural weathering of stone is accelerated by the combined effects of acid rain, salt crystallization and the freeze-thaw cycles of water. This dissertation describes the development of two anti-weathering preservation treatments that are specific to limestone surfaces. The first strategy involves the application of a surface-specific, bifunctional, passivating, coupling agent that binds to both the limestone surface and to a consolidating inorganic polymeric silica matrix by a sol-gel process. The second strategy involves biomimetic process that converts the exposed limestone surface into a nonreactive calcium oxalate hydrate ceramic layer found in kidney stones and lichen deposits. The microreactor environment of a scanning probe microscope (SPM) fluid cell was used to simulate acid rain effects on treated and untreated calcite surfaces, seen as etch pits and crystal step movement. The treatment process was also monitored at near molecular scale resolution using the SPM. Calcite crystals treated with aminoethylaminopropyltrimethoxysilane (25% AEAPS) passivating coupling agent and a silica consolidating solution (50%w/w), are resistant to the leaching action of deionized water equilibriated with atmospheric COsb2 to pH 5. The aminoalkoxylsilane coupling agent catalyses the condensation reaction and also reacts with the surface to offer the coupling mechanism. Modulus of rupture strength tests on limestone cores treated with the AEAPS and silica-based consolidant showed a 25-35% increase in strength. Environmental scanning electron microscopy of treated limestone exposed to concentrated sulfuric acid showed degradation of the surface except in areas where thick layers of the consolidant were deposited. Powder leach tests using a pH-stat apparatus yielded quantitative proof of the efficacy of the biomimetic calcium oxalate process. The dissolution rates (2.14×10sp{-9} mmol/cmsp2/sec) of treated calcite were two orders of magnitude less than untreated calcium carbonate (3.7×10sp{-7} mmol/cmsp2/sec) and an order of magnitude better than the sol-gel approach (3.5×10sp{-8} mmol/cmsp2/sec). Thus, we can extrapolate these results into a hybrid treatment of biomimetic calcium oxalate hydrate ceramic that provides the chemical leach resistance while a sol-gel passivation and consolidation step using aminoalkylsilane and silica, respectively, provides for improved strength and hydrophobicity.

Rao, Sudeep Motupalli

1998-12-01

180

Weather Instruments  

NSDL National Science Digital Library

This Topic in Depth discusses the variety of instruments used to collect climate and weather data. The first two websites provide simple introductions to the many weather instruments. Bethune Academy's Weather Center (1) discusses the functions of psychrometers, anemometers, weather balloons, thermometers, and barometers. The Illinois State Water Survey (2) furnishes many images of various instruments that collect data daily for legal issues, farmers, educators, students, and researchers. The third website (3), created by the Center for Improving Engineering and Science Education (CIESE), provides a classroom activity to educate users on how to build and use weather instruments. By the end of the group project, students should know all about wind vanes, rain gauges, anemometers, and thermometers. Next, the Miami Museum of Science provides a variety of activities to help students learn about the many weather instruments including wind scales and wind chimes (4). Students can learn about the wind, air pressure, moisture, and temperature. At the fifth website, the Tyson Research Center at Washington University describes the devices it uses in its research (5). At the various links, users can find out the center's many projects that utilize meteorological data such as acid rain monitoring. The sixth website, a pdf document created by Dr. John Guyton at the Mississippi State University Extension Service, provides guidance to teachers about the education of weather patterns and instruments (6). Users can find helpful information on pressure systems, humidity, cloud patterns, and much more. Next, the University of Richmond discusses the tools meteorologists use to learn about the weather (7). While providing materials about the basic tools discussed in the other websites, this site also offers information about weather satellites, radar, and computer models. After discovering the many weather instruments, users can learn about weather data output and analysis at the Next Generation Weather Lab website (8). This expansive website provides an abundance of surface data and upper air data as well as satellite and radar images for the United States.

181

Groundwater/surface-water interactions on deeply weathered surfaces of low relief: evidence from Lakes Victoria and Kyoga, Uganda  

NASA Astrophysics Data System (ADS)

Little is known of the interactions between groundwater and surface water on deeply weathered landscapes of low relief in the Great Lakes Region of Africa (GLRA). The role of groundwater in sustaining surface-water levels during periods of absent rainfall is disputed and groundwater is commonly excluded from estimations of surface-water balances. Triangulated piezometers installed beside lake gauging stations on Lake Victoria and Lake Kyoga in Uganda provide the first evidence of the dynamic interaction between groundwater and surface water in the GLRA. Stable isotope ratios (2H:1H, 18O:16O) support piezometric evidence that groundwater primarily discharges to lakes but show further that mixing of groundwater and lake water has occurred at one site on Lake Victoria (Jinja). Layered-aquifer heterogeneity, wherein fluvial-lacustrine sands overlie saprolite, gives rise to both rapid and slow groundwater fluxes to lakes which is evident from the recession of borehole hydrographs following recharge events. Darcy throughflow calculations suggest that direct contributions from groundwater to Lake Victoria comprise <1% of the total inflows to the lake. Groundwater/surface-water interactions are strongly influenced by changing drainage base (lake) levels that are controlled, in part, by regional climate variability and dam releases from Lake Victoria (Jinja).

Owor, Michael; Taylor, Richard; Mukwaya, Christine; Tindimugaya, Callist

2011-11-01

182

Temporal and spatial variation of surface reaction rates in porous media: Applications to silicate weathering  

NASA Astrophysics Data System (ADS)

Percolation theory provides a promising framework for modeling transport in heterogeneous porous media, including hydraulic and electrical conductivity, air permeability, gas diffusivity, and solute transport. Using percolation concepts (e.g., critical path analysis, fractal scaling of percolation clusters, and cluster statistics), we developed a physically-based model for predicting solute transport. Our model predicted spatial solute distributions as a function of time, and arrival time distributions as a function of system size. Our solute transport predictions gave good matches to a wide range of experiments. We now apply our solute transport model to silicate weathering. We assume that surface chemical reactions are at equilibrium at the scale of a single pore, but that at larger length scales, reactions are limited by transport of reactants or products. Using results from published field experiments, we find that the temporal and spatial dependence derived from solute velocity successfully predicts the measured time- and length-dependence of reaction rates and weathering of silicate minerals over a wide range of time and length scale. A similar analysis of lab experiments (uranium breakthrough curves measured in two short and long columns from the Hanford site) indicates that normalized reaction rate versus normalized time follow 2D invasion and 3D random percolation.

Ghanbarian, B.; Hunt, A. G.; Skinner, T. E.; Ewing, R. P.

2013-12-01

183

Observation of local cloud and moisture feedbacks over high ocean and desert surface temperatures  

NASA Technical Reports Server (NTRS)

New data on clouds and moisture, made possible by reanalysis of weather satellite observations, show that the atmosphere reacts to warm clusters of very high sea surface temperatures in the western Pacific Ocean with increased moisture, cloudiness, and convection, suggesting a negative feedback limiting the sea surface temperature rise. The reverse was observed over dry and hot deserts where both moisture and cloudiness decrease, suggesting a positive feedback perpetuating existing desert conditions. In addition, the observations show a common critical surface temperature for both oceans and land; the distribution of atmospheric moisture is observed to reach a maximum value when the daily surface temperatures approach 304 +/- 1 K. These observations reveal complex dynamic-radiative interactions where multiple processes act simultaneously at the surface as well as in the atmosphere to regulate the feedback processes.

Chahine, Moustafa T.

1995-01-01

184

Daymet: Daily Surface Weather Data on a 1-km Grid for North America, Version 2.  

SciTech Connect

More information: http://daymet.ornl.gov Presenter: Ranjeet Devarakonda Environmental Sciences Division Oak Ridge National Laboratory (ORNL) Daymet: Daily Surface Weather Data and Climatological Summaries provides gridded estimates of daily weather parameters for North America, including daily continuous surfaces of minimum and maximum temperature, precipitation occurrence and amount, humidity, shortwave radiation, snow water equivalent, and day length. The current data product (Version 2) covers the period January 1, 1980 to December 31, 2013 [1]. The prior product (Version 1) only covered from 1980-2008. Data are available on a daily time step at a 1-km x 1-km spatial resolution in Lambert Conformal Conic projection with a spatial extent that covers the conterminous United States, Mexico, and Southern Canada as meteorological station density allows. Daymet data can be downloaded from 1) the ORNL Distributed Active Archive Center (DAAC) search and order tools (http://daac.ornl.gov/cgi-bin/cart/add2cart.pl?add=1219) or directly from the DAAC FTP site (http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1219) and 2) the Single Pixel Tool [2] and THREDDS (Thematic Real-time Environmental Data Services) Data Server [3]. The Single Pixel Data Extraction Tool allows users to enter a single geographic point by latitude and longitude in decimal degrees. A routine is executed that translates the (lon, lat) coordinates into projected Daymet (x,y) coordinates. These coordinates are used to access the Daymet database of daily-interpolated surface weather variables. Daily data from the nearest 1 km x 1 km Daymet grid cell are extracted from the database and formatted as a table with one column for each Daymet variable and one row for each day. All daily data for selected years are returned as a single (long) table, formatted for display in the browser window. At the top of this table is a link to the same data in a simple comma-separated text format, suitable for import into a spreadsheet or other data analysis software. The Single Pixel Data Extraction Tool also provides the option to download multiple coordinates programmatically. A multiple extractor script is freely available to download at http://daymet.ornl.gov/files/daymet.zip. The ORNL DAAC s THREDDS data server (TDS) provides customized visualization and access to Daymet time series of North American mosaics. Users can subset and download Daymet data via a variety of community standards, including OPeNDAP, NetCDF Subset service, and Open Geospatial Consortium (OGC) Web Map/Coverage Service. The ORNL DAAC TDS also exposes Daymet metadata through its ncISO service to facilitate harvesting Daymet metadata records into 3rd party catalogs. References: [1] Thornton, P.E., M.M. Thornton, B.W. Mayer, N. Wilhelmi, Y. Wei, R. Devarakonda, and R.B. Cook. 2014. Daymet: Daily Surface Weather Data on a 1-km Grid for North America, Version 2. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. [2] Devarakonda R., et al. 2012. Daymet: Single Pixel Data Extraction Tool. Available on-line [http://daymet.ornl.go/singlepixel.html]. [3] Wei Y., et al. 2014. Daymet: Thematic Real-time Environmental Data Services. Available on-line [http://daymet.ornl.gov/thredds_tiles.html].

Thornton, Peter E [ORNL; Thornton, Michele M [ORNL; Mayer, Benjamin W [ORNL; Wilhelmi, Nate [National Center for Atmospheric Research (NCAR); Wei, Yaxing [ORNL; Devarakonda, Ranjeet [ORNL; Cook, Robert B [ORNL

2014-01-01

185

Surface studies of asteroids from earthbound observations  

NASA Astrophysics Data System (ADS)

The angular diameter of minor planets under the best observation conditions of about one arcsec (seeing) at ground-based observatories usually is too small to be resolved for surface studies or diameter determinations with direct photographic or similar imaging methods. Nevertheless, the rough geometry and/or small-scale structures on the asteroid surfaces can be studied with light curve observations using high-precision photoelectric photometry and the fact that the rotation of an asteroid during a spin period is now determined for slightly more than 200 minor planets. For only a few selected asteroids (63 Ausonia, 88 Thisbe, 92 Undina, 110 Lydia, 118 Peitho, 128 Nemesis, 139 Juewa, 337 Devosa, and 599 Luisa) it is shown from details detected in the light curves, how observations of this type were carried out successfully. From the small scale features, rough linear extensions on the asteroid surface are obtained from differences in magnitude and time. Such observations will be more useful and important in the future with respect to the optimum selection of objects for a possible direct asteroid spacecraft mission.

Schober, H. J.; Scaltriti, F.; Zappala, V.

1980-04-01

186

The Main Pillar: Assessment of Space Weather Observational Asset Performance Supporting Nowcasting, Forecasting and Research to Operations  

NASA Technical Reports Server (NTRS)

Space weather forecasting critically depends upon availability of timely and reliable observational data. It is therefore particularly important to understand how existing and newly planned observational assets perform during periods of severe space weather. Extreme space weather creates challenging conditions under which instrumentation and spacecraft may be impeded or in which parameters reach values that are outside the nominal observational range. This paper analyzes existing and upcoming observational capabilities for forecasting, and discusses how the findings may impact space weather research and its transition to operations. A single limitation to the assessment is lack of information provided to us on radiation monitor performance, which caused us not to fully assess (i.e., not assess short term) radiation storm forecasting. The assessment finds that at least two widely spaced coronagraphs including L4 would provide reliability for Earth-bound CMEs. Furthermore, all magnetic field measurements assessed fully meet requirements. However, with current or even with near term new assets in place, in the worst-case scenario there could be a near-complete lack of key near-real-time solar wind plasma data of severe disturbances heading toward and impacting Earth's magnetosphere. Models that attempt to simulate the effects of these disturbances in near real time or with archival data require solar wind plasma observations as input. Moreover, the study finds that near-future observational assets will be less capable of advancing the understanding of extreme geomagnetic disturbances at Earth, which might make the resulting space weather models unsuitable for transition to operations.

Posner, Arik; Hesse, Michael; SaintCyr, Chris

2014-01-01

187

Oscillation Responses to an Extreme Weather Event from a Deep Moored Observing System  

NASA Astrophysics Data System (ADS)

In June 2007 tropical Cyclone Gonu passed directly over an ocean observing system consisting of four, deep autonomous mooring stations along the 3000 m isobath in the northern Arabian Sea. Gonu was the largest cyclone known to have occurred in the Arabian Sea or to strike the Arabian Peninsula. The mooring system was designed by Lighthouse R & D Enterprises, Inc. and installed in cooperation with the Oman Ministry of Agriculture and Fisheries Wealth. The instruments on the moorings continuously recorded water velocities, temperature, conductivity, pressure, dissolved oxygen and turbidity at multiple depths and at hourly intervals during the storm. Near-inertial oscillations at all moorings from thermocline to seafloor are coincident with the arrival of Gonu. Sub-inertial oscillations with periods of 2-10 days are recorded at the post-storm relaxation stage of Gonu, primarily in the thermocline. These oscillations consist of warm, saline water masses, likely originating from the Persian Gulf. Prominent 12.7-day sub-inertial waves, measured at a station ~300 km offshore, are bottom-intensified and have characteristics of baroclinic, topographically-trapped waves. Theoretical results from a topographically-trapped wave model are in a good agreement with the observed 12.7-day waves. The wavelength of the 12.7-day waves is about 590 km calculated from the dispersion relationship. Further analysis suggests that a resonant standing wave is responsible for trapping the 12.7-day wave energy inside the Sea of Oman basin. The observational results reported here are the first measurements of deepwater responses to a tropical cyclone in the Sea of Oman/Arabian Sea. Our study demonstrates the utility of sustained monitoring for studying the impact of extreme weather events on the ocean.

Wang, Z.; Dimarco, S. F.; Stoessel, M. M.; Zhang, X.; Ingle, S.

2011-12-01

188

Sensitivity of Spacebased Microwave Radiometer Observations to Ocean Surface Evaporation  

NASA Technical Reports Server (NTRS)

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.; Li, Li

2000-01-01

189

The rate of chemical weathering of pyrite on the surface of Venus  

NASA Technical Reports Server (NTRS)

This abstract reports results of an experimental study of the chemical weathering of pyrite (FeS2) under Venus-like conditions. This work, which extends the earlier study by Fegley and Treiman, is part of a long range research program to experimentally measure the rates of thermochemical gas-solid reactions important in the atmospheric-lithospheric sulfur cycle on Venus. The objectives of this research are (1) to measure the kinetics of thermochemical gas-solid reactions responsible for both the production (e.g., anhydrite formation) and destruction (e.g., pyrrhotite oxidation) of sulfur-bearing minerals on the surface of Venus and (2) to incorporate these and other constraints into holistic models of the chemical interactions between the atmosphere and surface of Venus. Experiments were done with single crystal cubes of natural pyrite (Navajun, Logrono, Spain) that were cut and polished into slices of known weight and surface area. The slices were isothermally heated at atmospheric pressure in 99.99 percent CO2 (Coleman Instrument Grade) at either 412 C (685 K) or 465 C (738 K) for time periods up to 10 days. These two isotherms correspond to temperatures at about 6 km and 0 km altitude, respectively, on Venus. The reaction rate was determined by measuring the weight loss of the reacted slices after removal from the furnace. The reaction products were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy on the SEM.

Fegley, B., Jr.; Lodders, K.

1993-01-01

190

Observing Global Surface Water Flood Dynamics  

NASA Astrophysics Data System (ADS)

Flood waves moving along river systems are both a key determinant of globally important biogeochemical and ecological processes and, at particular times and particular places, a major environmental hazard. In developed countries, sophisticated observing networks and ancillary data, such as channel bathymetry and floodplain terrain, exist with which to understand and model floods. However, at global scales, satellite data currently provide the only means of undertaking such studies. At present, there is no satellite mission dedicated to observing surface water dynamics and, therefore, surface water scientists make use of a range of sensors developed for other purposes that are distinctly sub-optimal for the task in hand. Nevertheless, by careful combination of the data available from topographic mapping, oceanographic, cryospheric and geodetic satellites, progress in understanding some of the world's major river, floodplain and wetland systems can be made. This paper reviews the surface water data sets available to hydrologists on a global scale and the recent progress made in the field. Further, the paper looks forward to the proposed NASA/CNES Surface Water Ocean Topography satellite mission that may for the first time provide an instrument that meets the needs of the hydrology community.

Bates, Paul D.; Neal, Jefferey C.; Alsdorf, Douglas; Schumann, Guy J.-P.

2014-05-01

191

Global surface-based cloud observation for ISCCP  

NASA Technical Reports Server (NTRS)

Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight. Ten years of nighttime weather observations from the northern hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6 degrees or from a partial moon at higher elevation, or twilight from the sun less than 9 degrees below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon. The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is now found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans far from the continents, particularly in summer. However, near noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night, by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a few regions; they are generally in better agreement if the moonlight criterion is imposed on the surface observations. Using the moonlight criterion, we have analyzed ten years (1982-1991) of surface weather observations over land and ocean, worldwide, for total cloud cover and for the frequency of occurrence of clear sky, fog and precipitation The global average cloud cover (average of day and night) is about 2% higher if we impose the moonlight criterion than if we use all observations. The difference is greater in winter than in summer, because of the fewer hours of darkness in the summer. The amplitude of the annual cycle of total cloud cover over the Arctic Ocean and at the South Pole is diminished by a few percent when the moonlight criterion is imposed. The average cloud cover for 1982-1991 is found to be 55% for northern hemisphere land, 53% for southern hemisphere land, 66% for northern hemisphere ocean, and 70% for southern hemisphere ocean, giving a global average of 64%. The global average for daytime is 64.6% for nighttime 63.3%.

1994-01-01

192

Sensitivity of free tropospheric carbon monoxide to atmospheric weather states and their persistency: an observational assessment over the Nordic countries  

NASA Astrophysics Data System (ADS)

Among various factors that influence the long-range transport of pollutants in the free troposphere (FT), the prevailing atmospheric weather states probably play the most important role in governing characteristics and efficacy of such transport. The weather states, such as a particular wind pattern, cyclonic or anticyclonic conditions, and their degree of persistency determine the spatio-temporal distribution and the final fate of the pollutants. This is especially true in the case of Nordic countries, where baroclinic disturbances and associated weather fronts primarily regulate local meteorology, in contrast to the lower latitudes where a convective paradigm plays a similarly important role. Furthermore, the long-range transport of pollutants in the FT has significant contribution to the total column burden over the Nordic countries. However, there is insufficient knowledge on the large-scale co-variability of pollutants in the FT and atmospheric weather states based solely on observational data over this region. The present study attempts to quantify and understand this statistical co-variability while providing relevant meteorological background. To that end, we select eight weather states that predominantly occur over the Nordic countries and three periods of their persistency (3 days, 5 days, and 7 days), thus providing in total 24 cases to investigate sensitivity of free tropospheric carbon monoxide, an ideal tracer for studying pollutant transport, to these selected weather states. The eight states include four dominant wind directions (namely, NW, NE, SE and SW), cyclonic and anticyclonic conditions, and the enhanced positive and negative phases of the North Atlantic Oscillation (NAO). For our sensitivity analysis, we use recently released Version 6 retrievals of CO at 500 hPa from the Atmospheric Infrared Sounder (AIRS) onboard Aqua satellite covering the 11-year period from September 2002 through August 2013 and winds from the ECMWF's ERA-Interim project to classify weather states for the same 11-year period. We show that, among the various weather states studied here, southeasterly winds lead to highest observed CO anomalies (up to +8%) over the Nordic countries while transporting pollution from the central and eastern parts of Europe. The second (up to +4%) and third highest (up to +2.5%) CO anomalies are observed when winds are northwesterly (facilitating inter-continental transport from polluted North American regions) and during the enhanced positive phase of the NAO respectively. Higher than normal CO anomalies are observed during anticyclonic conditions (up to +1%) compared to cyclonic conditions. The cleanest conditions are observed when winds are northeasterly and during the enhanced negative phases of the NAO, when relatively clean Arctic air masses are transported over the Nordic regions in the both cases. In the case of nearly all weather states, the CO anomalies consistently continue to increase or decrease as the degree of persistency of a weather state is increased. The results of this sensitivity study further provide an observational basis for the process-oriented evaluation of chemistry transport models, especially with regard to the representation of large-scale coupling of chemistry and local weather states and its role in the long-range transport of pollutants in such models.

Thomas, M. A.; Devasthale, A.

2014-11-01

193

Sensitivity of free tropospheric carbon monoxide to atmospheric weather states and their persistency: an observational assessment over the Nordic countries  

NASA Astrophysics Data System (ADS)

Among various factors that influence the long-range transport of pollutants in the free troposphere (FT), the prevailing atmospheric weather states probably play the most important role in governing characteristics and efficacy of such transport. The weather states, such as a particular wind pattern, cyclonic or anticyclonic conditions etc, and their degree of persistency determine the spatio-temporal distribution and the final fate of the pollutants. This is especially true in the case of Nordic countries, where baroclinic disturbances and associated weather fronts primarily regulate local meteorology, in contrast to the lower latitudes where convective paradigm plays similar important role. Furthermore, the long-range transport of pollutants in the FT has significant contribution to the total column burden over the Nordic countries. However, there is insufficient knowledge on the large-scale co-variability of pollutants in the FT and atmospheric weather states based solely on observational data over this region. The present study attempts to quantify and understand this statistical co-variability while providing relevant meteorological background. To that end, we select eight weather states that predominantly occur over the Nordic countries and three periods of their persistency (3 days, 5 days, and 7 days), thus providing in total 24 cases to investigate sensitivity of free tropospheric carbon monoxide, an ideal tracer for studying pollutant transport, to these selected weather states. The eight states include four dominant wind directions (namely, NW, NE, SE and SW), cyclonic and anticyclonic conditions, and the enhanced positive and negative phases of the North Atlantic Oscillation (NAO). For our sensitivity analysis, we use recently released Version 6 retrievals of CO at 500 hPa from the Atmospheric Infrared Sounder (AIRS) onboard Aqua satellite covering 11 yr period from September 2002 through August 2013 and winds from the ECMWF's ERA-Interim project to classify weather states for the same 11 yr period. We show that, among the various weather states studied here, southeasterly winds lead to highest observed CO anomalies (up to +8%) over the Nordic countries while transporting pollution from the central and eastern parts of Europe. The second (up to +4%) and third highest (up to +2.5%) CO anomalies are observed when winds are northwesterly (facilitating inter-continental transport from polluted North American regions) and during the enhanced positive phase of the NAO respectively. Higher than normal CO anomalies are observed during anticyclonic conditions (up to +1%) compared to cyclonic conditions. The cleanest conditions are observed when winds are northeasterly and during the enhanced negative phases of the NAO, when relatively clean Arctic air masses are transported over the Nordic regions in the both cases. In case of nearly all weather states, the CO anomalies consistently continue to increase or decrease as the degree of persistency of a weather state is increased. The results of this sensitivity study further provide an observational basis for the process-oriented evaluation of chemistry transport models, especially with regard to the representation of large-scale coupling of chemistry and local weather states and its role in the long-range transport of pollutants in such models.

Thomas, M. A.; Devasthale, A.

2014-04-01

194

Understanding Aviation Meteorology and Weather Hazards with Ground-Based Observations  

Microsoft Academic Search

\\u000a Meteorology is no doubt important for aviation, as weather hazards have a significant negative impact on aircraft safety and\\u000a traffic delay. Based on recent surveys, 20–30% of worldwide air accidents and as much as 22% of air traffic delays are due\\u000a to to adverse weather conditions. Information on thunderstorms, ceiling and visibility, wind shear, turbulence, and aircraft\\u000a icing conditions are

Christian Pagé

195

Exploring Weather  

NSDL National Science Digital Library

Second Grade Standard 3: Students will develop an understanding of their environment. Objective 2: Observe and describe weather. Indicator a: Observe and describe patterns of change in weather. Monday, February 1st: Look at the five-day forecast for Salt Lake City, Utah at Five day forecasts. The high temperature for the day will be in red and the low temperature will be in blue. Make sure you look at the temperature listed in degrees Farenheit (F) not degrees Celcius (C). Make ...

Miss Emily

2010-01-29

196

Space Weathering of Small Bodies  

NASA Astrophysics Data System (ADS)

Space weathering is defined as any process that wears away and alters surfaces, here confined to small bodies in the Solar System. Mechanisms which possibly alter asteroid and comet surfaces include solar wind bombardment, UV radiation, cosmic ray bombardment, micrometeorite bombardment. These processes are likely to contribute to surface processes differently. For example, solar wind bombardment would be more important on a body closer to the Sun compared to a comet where cosmic ray bombardment might be a more significant weathering mechanism. How can we measure the effects of space weathering? A big problem is that we don't know the nature of the surface before it was weathered. We are in a new era in the study of surface processes on small bodies brought about by the availability of spatially resolved, color and spectral measurements of asteroids from Galileo and NEAR. What processes are active on which bodies? What physics controls surface processes in different regions of the solar system? How do processes differ on different bodies of different physical and chemical properties? What combinations of observable parameters best address the nature of surface processes? Are there alternative explanations for the observed parameters that have been attributed to space weathering? Should we retain the term, space weathering? How can our understanding of space weathering on the Moon help us understand it on asteroids and comets? Finally, we have to leave behind some presuppositions, one being that there is evidence of space weathering based on the fact that the optical properties of S-type asteroids differs from those of ordinary chondrites.

McFadden, L. A.

2002-12-01

197

Intersatellite calibration of AMSU-A observations for weather and climate applications  

NASA Astrophysics Data System (ADS)

Long-term observations from the Advanced Microwave Sounding Unit-A (AMSU-A) onboard polar-orbiting satellites NOAA 15, 16, 17, and 18 and European Meteorological Operational satellite program-A (MetOp-A) were intercalibrated using their overlap observations. Simultaneous nadir overpasses (SNOs) and global ocean mean differences between these satellites were used to characterize calibration errors and to obtain calibration coefficients. Calibration errors were found manifesting themselves as certain scatter or temporal patterns of intersatellite biases, such as well-defined seasonal cycles in the Arctic and Antarctic SNO difference time series or a unique pattern closely correlated to the instrument temperature variability induced by Solar Beta Angle (SBA) variations in global ocean mean difference time series. Analyses of these patterns revealed five different types of biases that need to be removed from existing prelaunch-calibrated AMSU-A observations, which include relatively stable intersatellite biases between most satellite pairs, bias drifts on NOAA 16 and channel 7 of MetOp-A, sun-heating-induced instrument temperature variability in radiances, scene temperature dependency in biases due to inaccurate calibration nonlinearity, and biases due to channel frequency shift from its prelaunch measurement in certain satellite channels. Level-1c time-dependent calibration offsets and nonlinear coefficients were introduced and determined from SNO and global ocean mean temperature regressions to remove or minimize the first four types of biases. Channel frequency shift in NOAA 15 channel 6 was obtained from the radiative transfer model simulation experiments. The new calibration coefficients and channel frequency values have significantly reduced the five different types of biases and resulted in more consistent multisatellite radiance observations for intercalibrated satellite channels. The intercalibrated AMSU-A observations have been merged with its precursor, the intercalibrated microwave sounding unit (MSU), to generate the NOAA/Center for Satellite Applications and Research (STAR) version 2.0 upper-air temperature climate data record (CDR) for climate trend and variability monitoring from 1979 to the present. The intercalibrated AMSU-A radiance data are expected to further improve accuracies of numerical weather prediction and consistencies in climate reanalysis and CDR developments.

Zou, Cheng-Zhi; Wang, Wenhui

2011-12-01

198

Chemical weathering rates of a soil chronosequence on granitic alluvium: I. Quantification of mineralogical and surface area changes and calculation of primary silicate reaction rates  

USGS Publications Warehouse

Mineral weathering rates are determined for a series of soils ranging in age from 0.2-3000 Ky developed on alluvial terraces near Merced in the Central Valley of California. Mineralogical and elemental abundances exhibit time-dependent trends documenting the chemical evolution of granitic sand to residual kaolinite and quartz. Mineral losses with time occur in the order: hornblende > plagioclase > K-feldspar. Maximum volume decreases of >50% occur in the older soils. BET surface areas of the bulk soils increase with age, as do specific surface areas of aluminosilicate mineral fractions such as plagioclase, which increases from 0.4-1.5 m2 g-1 over 600 Ky. Quartz surface areas are lower and change less with time (0.11-0.23 m2 g-1). BET surface areas correspond to increasing external surface roughness (?? = 10-600) and relatively constant internal surface area (??? 1.3 m2 g-1). SEM observations confirm both surface pitting and development of internal porosity. A numerical model describes aluminosilicate dissolution rates as a function of changes in residual mineral abundance, grain size distributions, and mineral surface areas with time. A simple geometric treatment, assuming spherical grains and no surface roughness, predicts average dissolution rates (plagioclase, 10-17.4; K-feldspar, 10-17.8; and hornblende, 10-17.5 mol cm-1 s-1) that are constant with time and comparable to previous estimates of soil weathering. Average rates, based on BET surface area measurements and variable surface roughnesses, are much slower (plagioclase, 10-19.9; K-feldspar, 10-20.5; and hornblende 10-20.1 mol cm-2 s-1). Rates for individual soil horizons decrease by a factor of 101.5 over 3000 Ky indicating that the surface reactivities of minerals decrease as the physical surface areas increase. Rate constants based on BET estimates for the Merced soils are factors of 103-104 slower than reported experimental dissolution rates determined from freshly prepared silicates with low surface roughness (?? <10). This study demonstrates that the utility of experimental rate constants to predict weathering in soils is limited without consideration of variable surface areas and processes that control the evolution of surface reactivity with time.

White, A.F.; Blum, A.E.; Schulz, M.S.; Bullen, T.D.; Harden, J.W.; Peterson, M.L.

1996-01-01

199

Chemical weathering rates of a soil chronosequence on granitic alluvium: I. Quantification of mineralogical and surface area changes and calculation of primary silicate reaction rates  

NASA Astrophysics Data System (ADS)

Mineral weathering rates are determined for a series of soils ranging in age from 0.2-3000 Ky developed on alluvial terraces near Merced in the Central Valley of California. Mineralogical and elemental abundances exhibit time-dependent trends documenting the chemical evolution of granitic sand to residual kaolinite and quartz. Mineral losses with time occur in the order: hornblende > plagioclase > K-feldspar. Maximum volume decreases of >50% occur in the older soils. BET surface areas of the bulk soils increase with age, as do specific surface areas of aluminosilicate mineral fractions such as plagioclase, which increases from 0.4-1.5 m 2 g -1 over 600 Ky. Quartz surface areas are lower and change less with time (0.11-0.23 m 2 g -1). BET surface areas correspond to increasing external surface roughness (? = 10-600) and relatively constant internal surface area (? 1.3 m 2 g -1). SEM observations confirm both surface pitting and development of internal porosity. A numerical model describes aluminosilicate dissolution rates as a function of changes in residual mineral abundance, grain size distributions, and mineral surface areas with time. A simple geometric treatment, assuming spherical grains and no surface roughness, predicts average dissolution rates (plagioclase, 10 -17.4; K-feldspar, 10 -17.8; and hornblende, 10 -17.5 mol cm -1 s -1) that are constant with time and comparable to previous estimates of soil weathering. Average rates, based on BET surface area measurements and variable surface roughnesses, are much slower (plagioclase, 10 -19.9; K-feldspar, 10 -20.5; and hornblende 10 -20.1 mol cm -2 s -1). Rates for individual soil horizons decrease by a factor of 10 1.5 over 3000 Ky indicating that the surface reactivities of minerals decrease as the physical surface areas increase. Rate constants based on BET estimates for the Merced soils are factors of 10 3-104 slower than reported experimental dissolution rates determined from freshly prepared silicates with low surface roughness (? < 10). This study demonstrates that the utility of experimental rate constants to predict weathering in soils is limited without consideration of variable surface areas and processes that control the evolution of surface reactivity with time.

White, Art F.; Blum, Alex E.; Schulz, Marjorie S.; Bullen, Tom D.; Harden, Jennifer W.; Peterson, Maria L.

1996-07-01

200

Soil, snow, weather, and sub-surface storage data from a mountain catchment in the rain-snow transition zone  

Technology Transfer Automated Retrieval System (TEKTRAN)

A comprehensive hydroclimatic data set is presented for the 2011 water year to improve understanding of hydrologic processes in the rain-snow transition zone. Catchment soil depths and surface texture from 57 points are presented along with soil moisture, snow cover, weather data, and associated hy...

201

Observation and research for strong meteor shower and related catastrophic space weather  

NASA Astrophysics Data System (ADS)

During the first international joint observation for strong meteor shower, we made multi-subject observations for Leonids and Draconids and their disaster space weather events by several methods. Combining the synthetical analysis of Leonids, Perseids and Draconids and their related data from 1957 to 2003, we sufficiently confirm that the periodic strong meteor showers can result in the formation of catastrophic space weather events. The following summing-up is confirmed basically: 1.The formation mechanism of the strong meteor shower There are meteoroids with high density and uneven distribution close the cometary nucleus, especially in the direction of opposite the Sun and backside of the nucleus. They can stretch 1-11AU along the cometary orbit and 1-5 (&sim10^3AU) cross the orbit. Therefore good displays of meteor shower (10---100 times as usual) or storms (103---104 times as usual) can occur when the Earth passes a high density meteoroid stream during the period of 3 years before and 5 years after the perihelion passage of the comet. During that period, bolides or shooting stars which are serious harmful to spaceflight security increase greatly to 3%~10%. This corrects the wrong point of view that the harmful micro-meteoroids to spaceflight security in period meteor showers are <1 g only. 2. The cosmic dust maintaining mechanism of long-life Es layer in mid-latitude area It is proved the life of Es layer increased greatly when most ions are long-life metal type ions (Fe +, Mg + ?? ) which composite coefficient is much smaller than that of molecule type ions(O2 + , NO + ?? ). The observation for about 50 years roughly approves that the blanketing frequency of Es layer (fb Es) abnormally increase in large area (>105km2) and lasting long time (>15 min) only when strong meteor shower occurred at night. It is not f, l and c type Es layer evolved from sequence Es layer. This shows that the cause of fb Es increase is that the ionosphere was bombarded by an additional swarm of cometary dusts, much smaller than those which produce an ionization trail that can be detected by radio detectors. 3. Spaceflight security During the strong meteor shower, bolides or shooting stars which mass may >1 g increase obviously. Since its kinetic energy is great, a bolide will explode when impacting on spacecraft to produce compress waves passing to inner wall, therefore possibly result in break, except for bringing sunken marks on the outer wall. In a word, the possible damage of strong meteor showers to big spacecraft and long time staying spacecraft can not be neglect. Launch of spaceflight should be evaded and security step for spaceflight in orbit should be taken during the strong meteor shower.

Ma, Y. H.; He, Y. W.; Xu, P. X.; Zhao, H. B.

2007-07-01

202

Near-Real Time Satellite-Retrieved Cloud and Surface Properties for Weather and Aviation Safety Applications  

NASA Technical Reports Server (NTRS)

Cloud properties determined from satellite imager radiances provide a valuable source of information for nowcasting and weather forecasting. In recent years, it has been shown that assimilation of cloud top temperature, optical depth, and total water path can increase the accuracies of weather analyses and forecasts. Aircraft icing conditions can be accurately diagnosed in near-­-real time (NRT) retrievals of cloud effective particle size, phase, and water path, providing valuable data for pilots. NRT retrievals of surface skin temperature can also be assimilated in numerical weather prediction models to provide more accurate representations of solar heating and longwave cooling at the surface, where convective initiation. These and other applications are being exploited more frequently as the value of NRT cloud data become recognized. At NASA Langley, cloud properties and surface skin temperature are being retrieved in near-­-real time globally from both geostationary (GEO) and low-­-earth orbiting (LEO) satellite imagers for weather model assimilation and nowcasting for hazards such as aircraft icing. Cloud data from GEO satellites over North America are disseminated through NCEP, while those data and global LEO and GEO retrievals are disseminated from a Langley website. This paper presents an overview of the various available datasets, provides examples of their application, and discusses the use of the various datasets downstream. Future challenges and areas of improvement are also presented.

Minnis, Patrick; Smith, William L., Jr.; Bedka, Kristopher M.; Nguyen, Louis; Palikonda, Rabindra; Hong, Gang; Trepte, Qing Z.; Chee, Thad; Scarino, Benjamin; Spangenberg, Douglas A.; Sun-Mack, Szedung; Fleeger, Cecilia; Ayers, J. Kirk; Chang, Fu-Lung; Heck, Patrick M.

2014-01-01

203

GONG Observations of Solar Surface Flows  

PubMed

Doppler velocity observations obtained by the Global Oscillation Network Group (GONG) instruments directly measure the nearly steady flows in the solar photosphere. The sun's differential rotation is accurately determined from single observations. The rotation profile with respect to latitude agrees well with previous measures, but it also shows a slight north-south asymmetry. Rotation profiles averaged over 27-day rotations of the sun reveal the torsional oscillation signal-weak, jetlike features, with amplitudes of 5 meters per second, that are associated with the sunspot latitude activity belts. A meridional circulation with a poleward flow of about 20 meters per second is also evident. Several characteristics of the surface flows suggest the presence of large convection cells. PMID:8662460

Hathaway; Gilman; Harvey; Hill; Howard; Jones; Kasher; Leibacher; Pintar; Simon

1996-05-31

204

An atomic force microscopy study of weathering of polyester\\/melamine paint surfaces  

Microsoft Academic Search

The use of an atomic force microscope (AFM) for rapid assessment of the durability of exterior polyester\\/melamine paints has been investigated. The study established an AFM imaging technique that produces data representative of weathering rates of paint films under a range of weathering regimes of varying severity. The effect of scan size on the average roughness parameter was investigated, leading

Simon Biggs; Christopher A Lukey; Geoffrey M Spinks; Siu-Tung Yau

2001-01-01

205

Satellite-based albedo, sea surface temperature and effective land roughness maps used in the HIRLAM model for weather and climate scenarios  

NASA Astrophysics Data System (ADS)

A study is conducted on the effect of introducing maps of geophysical parameters retrieved from satellite Earth Observation data into the atmospheric model HIRLAM (HIgh Resolution Limited Area Model). . The HIRLAM system was developed by the HIRLAM project group, a cooperative project of the national weather services in Denmark, Finland, Iceland, Ireland, the Netherlands, Norway and Sweden. It is currently used by weather services in several European countries. The exchanges of sensible heat, water vapour and momentum between the land- and ocean surface and the atmosphere are very important dynamical processes in this type of model. The results from the HIRLAM model when using the improved surface boundary conditions is validated from wind and temperature data at synoptic weather stations and surface flux data from land- and ocean meteorological masts in Denmark. The results from a set of scenarios covering the hurricane in Denmark in December 1999 and several springtime cases in 2000 show improved weather forecasts. The methodology on retrieving improved boundary conditions is based on satellite image data. Maps on the geophysical parameters albedo and sea surface temperature are retrieved at a 1 km spatial resolution from NOAA AVHRR. Furthermore, land cover maps based on Landsat TM satellite data are used to assess the regional roughness. The high-resolution land roughness map (Areal Systems Information in a 25 m pixel resolution) is area-averaged into effective roughness values (15 km grid) by using a non-linear aggregation technique (QJRMS 1999, vol 125, 2075-2102). The area-averaging is highly non-linear due to the turbulent physical processes involved. Thus the effective surface conditions cannot be obtained by simple averaging but only by a flow model taking horizontal advection into consideration. The effect of hedges in the landscape is included as a correction index based on a vector-based map. The land surface fluxes of heat and water vapour is also estimated from a new concept using vegetation state and surface temperatures from either NOAA AVHRR satellite data or HIRLAM model results. Furthermore, a one-year climate simulation will be carried out with the seasonal land surface effects included in the input conditions. This work is basic to improvements in global climate change predictions. Funding from Danish Research Agency to the SAT-MAP-CLIMATE project (5006-00-0063) is acknowledged.

Hasager, C. B.; Nielsen, N. W.; Christensen, J. H.; Soegaard, H.; Boegh, E.; Rasmussen, M. S.; Jensen, N. O.

2001-12-01

206

The Themis-Beagle families: Investigation of space-weathering processes on primitive surfaces  

NASA Astrophysics Data System (ADS)

In the past 20 years, enormous progress has been reached in the study of space-weathering (SW) effects on silicates and silicate asteroids. The so-called ordinary chondrite paradox, that is, lack of asteroids similar to the ordinary chondrites, which represent 80 % of meteorite falls, has been solved. These meteorites are now clearly related to S-type asteroids, as proved also by the direct measurements of the NEAR and HAYABUSA missions on the near-Earth asteroids Eros and Itokawa. Spectral differences between S-type asteroids and ordinary chondrites are caused by space-weathering effects, which produce a darkening in the albedo, a reddening of the spectra, and diminish the silicate absorption bands on the asteroids surfaces, exposed to cosmic radiation and solar wind. On the other hand, our understanding of space-weathering effects on primitive asteroids is still poor. Only few laboratory experiments have been devoted to the investigation of SW effects on dark carbonaceous chondrites and on complex organic materials. Irradiation of transparent organic materials produces firstly redder and darker materials that upon further processing turn flatter-bluish and darker (Kanuchova et al. 2012; Moroz et al. 2004). The Themis family is a natural laboratory to study primitive asteroids and space-weathering effects. The Themis family is located between 3.05 and 3.24 au, beyond the snow line, and it is composed of primitive asteroids. Themis is one of the most statistically reliable families in the asteroid belt. First discovered by Hirayama (1918), it has been identified as a family in all subsequent works, and it has 550 members as determined by Zappalà et al. (1995) and more than 4000 as determined by Nesvorny et al. (2010). The family formed probably about 2.3 Gyr ago as a result of a large-scale catastrophic disruption event of a parent asteroid 400 km in diameter colliding with a 190-km projectile (Marzari et al. 1995). Several Themis family members show absorption features associated to hydrated silicates, and, recently, water-ice and organics features have been detected on the surface of (24) Themis (Campins et al. 2010, Rivkin & Emery 2010). Hydrated silicates are produced by the aqueous-alteration process, which require low temperature (< 320 K) and the presence of liquid water in the past. The Themis family may be an important reservoir of water ice. Moreover, the main-belt comets 133P, 238P, and 176P seem to be related to the Themis family because of orbital proximities and spectral properties analogies. Within the old Themis family members, a young sub-family, Beagle, formed less than 10 Myr ago, has been identified. This sub-family has 65 members up to 2 km of diameter (Nesvorny et al. 2008). So, the Themis family is very important to shed light on the asteroid-comet continuum, to constrain the abundances of water ices in the outer part of the main belt, and to probe space-weathering effects on old Themis and young Beagle families' members. To investigate all these aspects, we carried out a spectroscopic survey in the visible and near-infrared range at the 3.6-m Italian telescope TNG (La Palma, Spain) during 6 nights in February and December 2012. We got new spectra of 8 Beagle and 22 Themis members using the DOLORES (with the LR-R and LR-B grisms) and the NICS (with the Amici prism) instruments. To look for possible coma around the targets, we also performed deep imaging in the R filter. Data are currently under analysis, and the results will be presented at the ACM meeting. None of the investigated spectra show water-ice absorption features at 1.5 and 2 microns, while few Themis members have visible absorption bands associated with hydrated silicates. The best meteoritic analogues to both Themis and Beagle members are the carbonaceous chondrites, especially CM2. The spectra of Beagle and Themis asteroids show significant differences: 'old' Themis members exhibit a wide range of spectra, including asteroids with blue/neutral and moderately red spectra (relative to the Sun), while the young Beagle members in

Fornasier, S.; Perna, D.; Lantz, C.; Barucci, M.

2014-07-01

207

Weather Forecasting  

NSDL National Science Digital Library

Weather Forecasting is a set of computer-based learning modules that teach students about meteorology from the point of view of learning how to forecast the weather. The modules were designed as the primary teaching resource for a seminar course on weather forecasting at the introductory college level (originally METR 151, later ATMO 151) and can also be used in the laboratory component of an introductory atmospheric science course. The modules assume no prior meteorological knowledge. In addition to text and graphics, the modules include interactive questions and answers designed to reinforce student learning. The module topics are: 1. How to Access Weather Data, 2. How to Read Hourly Weather Observations, 3. The National Collegiate Weather Forecasting Contest, 4. Radiation and the Diurnal Heating Cycle, 5. Factors Affecting Temperature: Clouds and Moisture, 6. Factors Affecting Temperature: Wind and Mixing, 7. Air Masses and Fronts, 8. Forces in the Atmosphere, 9. Air Pressure, Temperature, and Height, 10. Winds and Pressure, 11. The Forecasting Process, 12. Sounding Diagrams, 13. Upper Air Maps, 14. Satellite Imagery, 15. Radar Imagery, 16. Numerical Weather Prediction, 17. NWS Forecast Models, 18. Sources of Model Error, 19. Sea Breezes, Land Breezes, and Coastal Fronts, 20. Soundings, Clouds, and Convection, 21. Snow Forecasting.

John Nielsen-Gammon

1996-09-01

208

Characterization of space weathering from Lunar Reconnaissance Orbiter Camera ultraviolet observations of the Moon  

NASA Astrophysics Data System (ADS)

We investigate the effects of space weathering at ultraviolet wavelengths using a near-global seven-band (321-689 nm) mosaic from the Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC). We confirm that for moderate- to high-iron compositions (? 5 wt % FeO), the steeply positive UV slope at wavelengths <415 nm shallows with increasing exposure to space weathering. We measure these differences in LROC WAC data as variations in the 321/415 nm ratio, which has low values for fresh craters in the mare and moderate-iron highlands. For low-iron highland compositions, the break in slope occurs at shorter wavelengths, and it is instead the 321/360 nm ratio that increases with exposure to the space-weathering environment, whereas the 321/415 nm ratio appears to be largely controlled by the degree of shock experienced during the impact. The effects of shock may be more important at highland craters because modest shock pressures result in the solid-state transformation of plagioclase to its glass equivalent, maskelynite, and can help distinguish between primary shocked ejecta and locally exposed fresh material in rays. While all of the "fresh" craters we examined have UV spectral properties consistent with substantial alteration due to space weathering, the UV spectra of lunar swirls (magnetically shielded from the solar wind) are consistent with exposure of immature, crystalline material. Together these results suggest that lunar space weathering is dominated by the solar wind and "saturates" in the UV at Is/FeO values of ~40 (submature).

Denevi, Brett W.; Robinson, Mark S.; Boyd, Aaron K.; Sato, Hiroyuki; Hapke, Bruce W.; Hawke, B. Ray

2014-05-01

209

Lunar mare soils: Space weathering and the major effects of surface-correlated nanophase Fe  

NASA Astrophysics Data System (ADS)

Lunar soils form the ``ground truth'' for calibration and modeling of reflectance spectra for quantitative remote sensing. The Lunar Soil Characterization Consortium, a group of lunar sample and remote sensing scientists, has undertaken the extensive task of characterization of lunar soils, with respect to their mineralogical and chemical makeup. This endeavor is aimed at deciphering the effects of space weathering of soils from the Moon, and these results should apply to other airless bodies. Modal abundances and chemistries of minerals and glasses in the <45 ?m size fractions of nine selected mare soils have been determined, along with the bulk chemistry of each size fraction, and their IS/FeO values. These data can be addressed at http:/web.utk.edu/~pgi/data.html. As grain size decreases, the bulk composition of each size fraction continuously changes and approaches the composition of the agglutinitic glasses. Past dogma had it that the majority of the nanophase Fe0 resides in the agglutinitic glasses. However, as grain size of a soil decreases, the percentage of the total iron present as nanophase-sized Fe0 increases dramatically, while the agglutinitic glass content rises only slightly. This is evidence for a large contribution to the IS/FeO values from surface-correlated nanophase Fe0, particularly in the <10 ?m size fraction. This surficial nanophase Fe0 is present largely as vapor-deposited patinas on the surfaces of almost every particle of the mature soils. It is proposed that these vapor-deposited, nanophase Fe0-bearing patinas may have far greater effects upon reflectance spectra of mare soils than the agglutinitic Fe0.

Taylor, Lawrence A.; Pieters, Carlé M.; Keller, Lindsay P.; Morris, Richard V.; McKay, David S.

2001-11-01

210

Environmental Education Tips: Weather Activities.  

ERIC Educational Resources Information Center

Provides weather activities including questions, on weather, heating the earth's surface, air, tools of the meteorologist, clouds, humidity, wind, and evaporation. Shows an example of a weather chart activity. (RT)

Brainard, Audrey H.

1989-01-01

211

The Effects of Chemical Weathering on Thermal-Infrared Spectral Data and Models: Implications for Aqueous Processes on the Martian Surface  

NASA Astrophysics Data System (ADS)

Chemical and mineralogical data from Mars shows that the surface has been chemically weathered on local to regional scales. Chemical trends and the types of chemical weathering products present on the surface and their abundances can elucidate information about past aqueous processes. Thermal-infrared (TIR) data and their respective models are essential for interpreting Martian mineralogy and geologic history. However, previous studies have shown that chemical weathering and the precipitation of fine-grained secondary silicates can adversely affect the accuracy of TIR spectral models. Furthermore, spectral libraries used to identify minerals on the Martian surface lack some important weathering products, including poorly-crystalline aluminosilicates like allophane, thus eliminating their identification in TIR spectral models. It is essential to accurately interpret TIR spectral data from chemically weathered surfaces to understand the evolution of aqueous processes on Mars. Laboratory experiments were performed to improve interpretations of TIR data from weathered surfaces. To test the accuracy of deriving chemistry of weathered rocks from TIR spectroscopy, chemistry was derived from TIR models of weathered basalts from Baynton, Australia and compared to actual weathering rind chemistry. To determine how specific secondary silicates affect the TIR spectroscopy of weathered basalts, mixtures of basaltic minerals and small amounts of secondary silicates were modeled. Poorly-crystalline aluminosilicates were synthesized and their TIR spectra were added to spectral libraries. Regional Thermal Emission Spectrometer (TES) data were modeled using libraries containing these poorly-crystalline aluminosilicates to test for their presence on the Mars. Chemistry derived from models of weathered Baynton basalts is not accurate, but broad chemical weathering trends can be interpreted from the data. TIR models of mineral mixtures show that small amounts of crystalline and amorphous silicate weathering products (2.5-5 wt.%) can be detected in TIR models and can adversely affect modeled plagioclase abundances. Poorly-crystalline aluminosilicates are identified in Northern Acidalia, Solis Planum, and Meridiani. Previous studies have suggested that acid sulfate weathering was the dominant surface alteration process for the past 3.5 billion years; however, the identification of allophane indicates that alteration at near-neutral pH occurred on regional scales and that acid sulfate weathering is not the only weathering process on Mars.

Rampe, Elizabeth Barger

2011-12-01

212

Fluorescent beeswax for surface flow velocity observations  

NASA Astrophysics Data System (ADS)

Watershed surface processes control downstream runoff phenomena, waste and pollutant diffusion, erosion mechanics, and sediment transport. A quantitative understanding of the flow physics is currently limited by the lack of effective tracing techniques suitable for basin-scale observations. More specifically, field experiments require environmentally resilient, non-invasive, and low cost measurement systems that can potentially operate in remotely-controlled or unmanned conditions. Traditional tracing methodologies are largely not capable to cope with extreme in-situ conditions, including practical logistic challenges as well as inherent flow complexity. Specifically, most of available technologies need physical sampling to estimate the tracer concentration and do not allow for continuous-time measurements. In addition, commonly used tracers, such as isotopes, dyes, and chemicals, are not directly applicable to monitor surface hillslope processes and large-scale microchannel networks due to elaborate detection processes and dispersion issues. In this context, the feasibility of using buoyant fluorescent microspheres as particle tracers in natural water flows is investigated. Specifically, a novel fabrication methodology is designed to manufacture particles from natural beeswax and a highly diluted solution of a nontoxic fluorescent red dye. The fabrication procedure allows for adjusting the size of the particles from tens of microns up to a few millimeters and their density from positively to negatively-buoyant with respect to water. An array of experimental techniques is employed to conduct a thorough characterization of the fluorescence and morphology of the tracers. In addition, ad-hoc experiments are designed to assess the fluorescence response due to Ultra Violet (UV) exposure and thermal processes. Proof-of-concept laboratory analysis are conducted to illustrate the integration of the novel particle tracers in existing tracing methods for surface flow analysis.

Grimaldi, S.; Tauro, F.; Petroselli, A.; Mocio, G.; Capocci, I.; Rapiti, E.; Rapiti, R.; Cipollari, G.; Porfiri, M.

2012-12-01

213

BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment  

USGS Publications Warehouse

BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 ?m) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

2014-01-01

214

Weather Maps in Motion  

NSDL National Science Digital Library

In this activity, students learn to interpret current weather maps. They will observe weather map loop animations on the internet, learn the concept of Zulu time (Universal Time Coordinated, UTC) and visualize the movement of fronts and air masses. They will then analyze a specific weather station model, generate a meteogram from their observations, and answer a set of questions about their observations.

Charles Burrows

215

Simulation studies of the impact of future observing systems on weather prediction  

NASA Technical Reports Server (NTRS)

The features and preliminary results from a simulation system being implemented to develop realistic estimates of the impacts future data acquisition systems will have on large-scale numerical weather simulation are described. The new instruments may include advanced passive IR and microwave satellite sensors, as well as active scatterometer and lidar sounders. A main goal of the impact study is to identify those sensor systems which will provide the most benefit. The realism of the study is being enhanced by assimilating as much real-world data as possible and generating global weather maps for comparison with maps generated on the bases on the projected new, higher resolution data. Early results have indicated a preference for higher resolution wind data than for temperature data for making 1-5 day forecasts. The prime instrument candidate for collecting the data is lidar, provided the sensor resolution design goals are met.

Atlas, R.; Kalnay, E.; Baker, W. E.; Susskind, J.; Reuter, D.; Halem, M.

1985-01-01

216

What's the Weather?  

NSDL National Science Digital Library

In this lesson, students use daily observations, videos, and activities to learn about meteorology and the changing nature of weather. They will also identify weather events that are commonly reported in the news and discuss how weather affects lives. They should understand that weather can change daily and weather patterns change over the seasons, and that it has characteristics that can be measured and predicted. Suggestions for an optional field trip are also provided.

2005-01-01

217

Australian Severe Weather  

NSDL National Science Digital Library

The Australian Severe Weather Web site is maintained by self proclaimed severe weather enthusiasts Michael Bath and Jimmy Deguara. Other weatherphobes will fully appreciate what the authors have assembled. Everything from weather images, storm news, tropical cyclone data, bush fire and wild fire information, weather observation techniques, and even video clips and Web cam links. Although these other items make the site well rounded, the extensive amount of categorized weather pictures (which are quite extraordinary) are reason enough to visit.

218

SPACE WEATHERING OF ROCK SURFACE WITHOUT REGOLITH: LABORATORY SIMULATION OF SPECTRAL CHANGE, S. Sasaki1  

E-print Network

of nanophase metallic iron particles [1], existence of which wa confirmed in the rim of lunar soil grains [2- 4 are explained by the so-called "space weathering". One proven mechanism of such spectral change is production

Hiroi, Takahiro

219

Surface deterioration of wood-flour polypropylene composites by weathering trials  

Microsoft Academic Search

The market for wood-fiber plastic composites (WPCs) is expanding rapidly in many countries including Japan, where WPCs are\\u000a mainly used for exterior products. In such applications, WPCs undergo undesirable color change, chalking, and shrinkage and\\u000a swelling, and accordingly there is a need to better understand the mechanisms responsible for the weathering of WPC and develop\\u000a methods of improving their weathering

Makoto Kiguchi; Yutaka Kataoka; Hiroshi Matsunaga; Koichi Yamamoto; Philip D. Evans

2007-01-01

220

Observation and modelling of stable isotopes in precipitation for midlatitude weather systems in Melbourne, Australia  

NASA Astrophysics Data System (ADS)

The application of stable water isotopes as tracers of moisture throughout the hydrological cycle is often hindered by the relatively coarse temporal and spatial resolution of observational data. Intensive observation periods (IOPs) of isotopes in precipitation have been valuable in this regard enabling the quantification of the effects of vapour recycling, convection, cloud top height and droplet reevaporation (Dansgaard, 1953; Miyake et al., 1968; Gedzelman and Lawrence, 1982; 1990; Pionke and DeWalle, 1992; Risi et al., 2008; 2009) and have been used as a basis to develop isotope models of varying complexity (Lee and Fung, 2008; Bony et al., 2008). This study took a unified approach combining observation and modelling of stable isotopes in precipitation in an investigation of three key circulation types that typically bring rainfall to southeastern Australia. The observational component of this study involved the establishment of the Melbourne University Network of Isotopes in Precipitation (MUNIP). MUNIP was devised to sample rainwater simultaneously at a number of collection sites across greater Melbourne to record the spatial and temporal isotopic variability of precipitation during the passage of particular events. Samples were collected at half-hourly intervals for three specific rain events referred to as (1) mixed-frontal, (2) convective, and (3) stratiform. It was found that the isotopic content for each event varied over both high and low frequencies due to influences from local changes in rain intensity and large scale rainout respectively. Of particular note was a positive relationship between deuterium excess and rainfall amount under convective conditions. This association was less well defined for stratiform rainfall. As a supplement to the data coverage of the observations, the events were simulated using a version of NCAR CAM3 running with an isotope hydrology scheme. This was done by periodically nudging the model dynamics with data from the NCEP Reanalysis (Noone, 2006). Results from the simulations showed that the model represented well the large scale evolution of vapour profiles of deuterium excess and 18O for the mixed-frontal and stratiform events. Reconstruction of air mass trajectories provided further detail of the evolution and structure of the vapour profiles revealing a convergence of air masses from different source regions for the mixed-frontal event. By combining observations and modelling in this way, much detail of the structure and isotope moisture history of the observed events was provided that would be unavailable from the sampling of precipitation alone. References Bony, S., C. Risi, and F. Vimeux (2008), Influence of convective processes on the isotopic composition (?18O and ?D) of precipitation and water vapor in the tropics: 1. Radiative-convective equilibrium and Tropical Ocean-Global Atmosphere-Coupled Ocean-Atmosphere Response (TOGA-COARE) simulations, J. Geophys. Res., 113, D19305, doi:10.1029/2008JD009942. Dansgaard, W. (1953), The abundance of 18O in atmospheric water and water vapor. Tellus, 5, 461-469. Gedzelman, S. D., and J. R. Lawrence (1982), The isotopic composition of cyclonic precipitation. J. App. Met., 21, 1385-1404. Gedzelman, S. D., and J. R. Lawrence (1990), The isotopic composition of precipitation from two extratropical cyclones, Mon. Weather Rev., 118 , 495-509. Lee, J., and I. Fung (2008), 'Amount effect' of water isotopes and quantitative analysis of post-condensation processes, Hydrol. Process., 22, 1-8. Miyake, Y., O. Matsubaya, and C. Nishihara (1968), An isotopic study on meteoric precipitation, Pap. Meteorol. Geophys., 19, 243-266. Noone, D. (2006), Isotopic composition of water vapor modeled by constraining global climate simulations with reanalyses, in Research activities in atmospheric and oceanic modeling, J. Côté (ed.), Report No. 36, WMO/TD-No. 1347, p. 2.37-2.38. Pionke, H. B., and D. R. DeWalle (1992), Intra- and inter-storm 18O trends for selected rainstorms in Pennsylvania. J. Hydrol., 138, 131-143. Risi, C., S. Bony, and F. Vimeux (20

Barras, Vaughan; Simmonds, Ian

2010-05-01

221

Space Weathering Products Found on the Surfaces of the Itokawa Dust Particles: A Summary of the Initial Analysis  

NASA Technical Reports Server (NTRS)

Surfaces of airless bodies exposed to interplanetary space gradually have their structures, optical properties, chemical compositions, and mineralogy changed by solar wind implantation and sputtering, irradiation by galactic and solar cosmic rays, and micrometeorite bombardment. These alteration processes and the resultant optical changes are known as space weathering [1, 2, 3]. Our knowledge of space weathering has depended almost entirely on studies of the surface materials returned from the Moon and regolith breccia meteorites [1, 4, 5, 6] until the surface material of the asteroid Itokawa was returned to the Earth by the Hayabusa spacecraft [7]. Lunar soil studies show that space weathering darkens the albedo of lunar soil and regolith, reddens the slopes of their reflectance spectra, and attenuates the characteristic absorption bands of their reflectance spectra [1, 2, 3]. These changes are caused by vapor deposition of small (<40 nm) metallic Fe nanoparticles within the grain rims of lunar soils and agglutinates [5, 6, 8]. The initial analysis of the Itokawa dust particles revealed that 5 out of 10 particles have nanoparticle-bearing rims, whose structure varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles (npFe) exist in a thin (5-15 nm) surface layer (zone I) on olivine, low-Ca pyroxene, and plagioclase, suggestive of vapor deposition. Sulfur-free npFe exist deeper inside (<60 nm) ferromagnesian silicates (zone II). Their texture suggests formation by amorphization and in-situ reduction of Fe2+ in ferromagnesian silicates [7]. On the other hand, nanophase metallic iron (npFe0) in the lunar samples is embedded in amorphous silicate [5, 6, 8]. These textural differences indicate that the major formation mechanisms of the npFe0 are different between the Itokawa and the lunar samples. Here we report a summary of the initial analysis of space weathering of the Itokawa dust particles.

Noguchi, T.; Kimura, M.; Hashimoto, T.; Konno, M.; Nakamura, T.; Ogami, T.; Ishida, H.; Sagae, R.; Tsujimoto, S.; Tsuchiyama, A,; Zolensky, M. E.; Tanaka, M.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

2012-01-01

222

Weathering Experiments  

NSDL National Science Digital Library

This experiment is designed to allow students to observe and understand chemical and physical weathering of simulated "rocks". They will place the materials in plastic bags, one wet and one dry, and store them for 3-4 days. At the end of the storage period, they will observe the contents of both bags and answer some questions about what they see.

223

Comparative Analysis of Thunderstorm Activity in the West Caucasus According to the Instrumental Measurements and Weather Stations Observations  

NASA Astrophysics Data System (ADS)

The number of thunderstorms days is one of the main characteristics of thunderstorms. In most cases, the number of days with different meteorological phenomena are the climate characteristic of the area. This characteristic is a common climate indicator. The comparative analysis of thunderstorms days quantity, received with lightning detector LS 8000 by Vaisala and weather stations of Krasnodar District (Russia), is presented. For this purpose the Krasnodar region was divided into 19 sites. The thunderstorm days amount and their comparison were conducted for each site according to the data of weather stations and LS 8000 lightning detectors. Totally 29 weather stations are located in this area. The number of thunderstorm days per year for the period of 2009-2012 was determined according to data, received from stations. It was received that average annual number of thunderstorm days for this area was from 33 to 39 days. The majority of thunderstorm days per year (up to 77) was registered in the south of Krasnodar region and on the Black Sea coast. The lowest thunderstorm activity (about 20 days) was observed in the North of the region. To compare visual and voice data for calculating thunderstorm days quantity of the Krasnodar region, the day was considered thundery if at least one weather station registered a storm. These instrumental observations of thunderstorms allow to obtain the basic characteristics and features of the distribution of thunderstorm activity over a large territory for a relatively short period of time. However, some characteristics such as thunderstorms intensity, damages from lightning flashes and others could be obtained only with instrumental observations. The territory of gathering thunderstorm discharges data by system LS8000 is limited by perimeter of 2250 km and square of 400 000 km2. According to the instrumental observations, the majority of storm activity also takes place on the Black Sea coast, near the cities of Sochi and Tuapse. Thus the number of thunderstorm days data characterized by the values from 49 to 158. To compare instrumental and visual-voice observations the difference between thunderstorms days quantity, obtained with visual-voice and instrumental methods, was selected as an indicator of thunderstorm activity. Total number of thunderstorm days in the Krasnodar region during 4 years is 565 according to the lightning detectors and 519 according to the weather stations. The presence of significant differences was revealed to compare number of thunderstorm days between instrumental observations and weather stations data. Thus the value of the average number of thunderstorms days on 29 meteorological stations of the Krasnodar region is reached 33-39 days. At the same time, 49-138 thunderstorm days were recorded according to the LS8000 system. This difference is caused by two factors: 1) limitations of visual-audio thunderstorms detection method at weather stations; 2) development of thunderstorms in a limited areas of the Krasnodar region, which is not the whole territory.

Knyazeva, Zalina; Gergokova, Zainaf; Gyatov, Ruslan; Boldyreff, Anton

2014-05-01

224

Comparative study of pulsed laser cleaning applied to weathered marble surfaces  

NASA Astrophysics Data System (ADS)

The removal of unwanted matter from surface stones is a demanding task in the conservation of cultural heritage. This paper investigates the effectiveness of near-infrared (IR) and ultraviolet (UV) laser pulses for the cleaning of surface deposits, iron oxide stains and different types of graffiti (black, red and green sprays and markers, and black cutting-edge ink) on dolomitic white marble. The performance of the laser techniques is compared to common cleaning methods on the same samples, namely pressurized water and chemical treatments. The degree of cleaning achieved with each technique is assessed by means of colorimetric measurements and X-ray microfluorescence. Eventual morphological changes induced on the marble substrate are monitored with optical and electronic microscopy. It is found that UV pulsed laser ablation at 266 nm manages to clean all the stains except the cutting-edge ink, although some degree of surface erosion is produced. The IR laser pulses at 1064 nm can remove surface deposits and black spray acceptably, but a yellowing is observed on the stone surface after treatment. An economic evaluation shows that pulsed laser cleaning techniques are advantageous for the rapid cleaning of small or inaccessible surface areas, although their extensive application becomes expensive due to the long operating times required.

Ortiz, P.; Antúnez, V.; Ortiz, R.; Martín, J. M.; Gómez, M. A.; Hortal, A. R.; Martínez-Haya, B.

2013-10-01

225

The Surface of Titan: Arecibo Radar Observations  

NASA Astrophysics Data System (ADS)

The Arecibo 12.6 cm radar system was used to obtain echo spectra for Titan in late 2001 and late 2002. A circularly polarized signal was transmitted with the Arecibo 305 m antenna and the echo was received in both the OC (expected for a mirror like reflection) and SC senses of circular polarization. For most of the observations Arecibo was used to receive the echo but for one observation in 2001 and for most of the 2002 observations the new 100 m Green Bank Telescope (GBT) was also used. Arecibo's limited tracking time combined with the 2 hr 15 min round-trip-light time to the Saturn system meant that it could only receive the echo for about 30 min corresponding to 0.5 deg of Titan rotation. For echo reception with the GBT the signal-to-noise ratio is lower but the echo can be received for the full round-trip-time corresponding to over 2 deg of motion of the sub-earth point on Titan. Sixtenn spectra were obtained in 2001 at sub-earth points uniformly spaced over the full range of longitudes. The 9 Arecibo/Arecibo and 15 Arecibo/GBT observations in 2002 did not provide uniform coverage. The latitudes of the sub-earth tracks in 2001 and 2002 were 25.9S and 26.2S, respectively. Most of the echo power is contained in a broad diffuse component. However, about 70% of the spectra show a weak specular echo that varies in width and amplitude with sub-earth longitude. The disk averaged normalized radar backscatter cross section varies from about 0.12 near 270 deg to about 0.19 at 90 deg, the longitude of the high near-IR albedo feature. The errors on these values are dominated by systematic errors of about 30%. The circular polarization ratio varies from about 0.4 to 0.6. The OC cross sections as a function of sub-earth longitude correlate very strongly with the disk integrated 2 micron albedoes from Griffith et al (1998). Fits of combined diffuse and specular scattering laws to the 16 2001 spectra resulted in 12 statistically significant specular echoes with the normalized cross sections ranging from 0.007 to 0.04 and rms slopes from 0.5 deg to 3.5 deg. These values for the cross sections are generally consistent with those expected for reflections from liquid hydrocarbons. A mix of liquid ethane, methane and nitrogen at Titan's surface temperature has a dielectric constant in the range of 1.65 to 1.81 (Thompson and Squyres, 1990) corresponding to radar cross sections between 0.016 to 0.022. The measured cross sections are also consistent with reflections from a higher dielectric constant surface of which only a fraction is smooth enough to give a specular echo. References: Griffith, C.A., T. Owen, G.A. Miller and T. Geballe, Nature, 395, 575-578, 1998. Thompson, W.R. and S.W. Squyres, Icarus, 86, 336-354, 1990.

Campbell, D. B.; Black, G. J.; Carter, L. M.; Ostro, S. J.

2003-12-01

226

Spectral observations of 19 weathered and 23 fresh NEAs and their correlations with orbital parameters  

NASA Astrophysics Data System (ADS)

Results of our visible to near-infrared spectrophotometric observations of 41 near-Earth asteroids (NEAs) are reported. These moderate-resolution spectra, along with 14 previously published spectra from our earlier survey [Hicks, M.D., Fink, U., Grundy, W.M., 1998. Icarus 133, 69-78] show a preponderance of spectra consistent with ordinary chondrites (23 NEAs with this type of spectrum, along with 19 S-types and 13 in other taxonomic groups). There exists statistically significant evidence for orbit-dependent trends in our data. While S-type NEAs from our survey reside primarily in (1) Amor orbits or (2) Aten or Apollo orbits which do not cross the asteroid main-belt, the majority of objects with spectra consistent with ordinary chondrites in our survey are in highly eccentric Apollo orbits which enter the asteroid main-belt. This trend toward fresh, relatively unweathered NEAs with ordinary chondrite type spectra in highly eccentric Apollo orbits is attributed to one or a combination of three possible causes: (1) the chaotic nature of NEA orbits can easily result in high eccentricity orbits/large aphelion distances so that they can enter the collisionally enhanced environment in the main-belt, exposing fresh surfaces, (2) they have recently been injected into such orbits after a collision in the main-belt, or (3) such objects cross the orbits of several terrestrial planets, causing tidal disruption events that expose fresh surfaces.

Fevig, Ronald A.; Fink, Uwe

2007-05-01

227

Martian Weather: Approximately 5 Mars Years of MOC and MARCI Observations  

NASA Astrophysics Data System (ADS)

From its nearly circular, polar orbit, the Mars Reconnaissance Orbiter (MRO) spacecraft provides the Mars Color Imager (MARCI) a daily global view of Mars. This permits MARCI observations to extend the 5 Mars year record of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) global, visible-wavelength observations of Martian meteorological events. It was fortunate that MGS lasted long enough to provide 3 weeks of overlapping coverage with MARCI. During this period in northern summer, the peak water-ice opacity of the orographic clouds over Olympus Mons increased from 0.7 to 1.4 between 1400 and 1500 LMST. MARCI also extended the monitoring of the year-to-year repeatable northern summer/southern winter dust storm and water-ice cloud phenomena observed by Cantor et al. (2002). As forecast, all three atmospheric events (Melas dust storm, spiral storm in the caldera of Arsia Mons, and the northern hemisphere extratropical annular water-ice cloud) reoccurred again in 2006-2007. The onset of the annular cloud appears to be the most highly repeatable from year-to-year, suggesting a strong thermal and/or topographic control. The Arsia Mons spiral storm occurred earlier this Mars year (Ls=150), while the Melas storm occurred later (Ls=146) than in previous years. In terms of large-scale atmospheric events, MOC (2001) and MARCI (2007) were fortunate to observe the formation of planet obscuring dust cloud events. Due to past observational limitations, such events have been called "Global" or "Planet-Encircling" dust storms. MOC and MARCI observations clearly show such events are not single storms, but are comprised of a number of regional and local dust storms that appear to be causally linked. These storms loft dust high into the atmosphere, where it is quickly circulated around the planet, obscuring the surface from orbital views for weeks to months at a time. This research was supported by NASA/JPL contracts NNH07CC11C and 1275776.

Cantor, Bruce; Malin, M. C.

2007-10-01

228

Wonderful Weather  

NSDL National Science Digital Library

Second Grade Standard 3: Students will develop an understanding of their environment. Objective 2: Observe and describe weather. Indicator a: Observe and describe patterns of change in weather. Monday November 6th: Look at the five-day forecast for Logan Utah at Five Day Forecast in Utah. The high temperature for the day will be in red and the low temperature will be in blue. Look at the temperature listed in degrees Farenheit (F) not degrees Celcius (C). Make a bar graph for the ...

Ms. Broadhead

2007-11-06

229

Assimilation of GOES Land Surface Data: Benefits to Numerical Weather Prediction  

NASA Technical Reports Server (NTRS)

A technique has been developed for assimilating GOES-derived skin temperature tendencies and insolation into the surface energy budget equation of a mesoscale model so that the simulated rate of temperature change closely agrees with the satellite observations. A critical assumption of the technique is that the availability of moisture (either from the soil or vegetation) is the least known term in the model's surface energy budget. Therefore, the simulated latent heat flux, which is a function of surface moisture availability, is adjusted based upon differences between the modeled and satellite observed skin temperature tendencies. An advantage of this technique is that satellite temperature tendencies are assimilated in an energetically consistent manner that avoids energy imbalances and surface stability problems that arise from direct assimilation of surface shelter temperatures. The fact that the rate of change of the satellite skin temperature is used rather than the absolute temperature means that sensor calibration is not as critical. The technique has been employed on a semi-operational basis at the GHCC within the PSU/CAR MM5 since 1 November 1998. A one-way nested grid configuration was employed with a 75 kin CONUS domain and a 25 km grid over the southeastern United States. Initial conditions were obtained from the 12 UTC Early Eta Data Assimilation System analyses and lateral boundary conditions from the Early Eta forecast available at 3 hour intervals. The satellite-derived land surface temperature tendencies and insolation were assimilated between two and five hours (1400 and 1650 UTC) of the forecast. We performed the assimilation on the Southeastern domain only. In addition, a control run without assimilation was performed to provide insight into the performance of the assimilation technique.

Lapenta, William M.; Suggs, Ron; McNider, Richard T.; Jedlovec, Gary; Dembek, Scott; Goodman, H. Michael (Technical Monitor)

2001-01-01

230

The influence of weather conditions on the activity of high-arctic arthropods inferred from long-term observations  

PubMed Central

Background Climate change is particularly pronounced in the High Arctic and a better understanding of the repercussions on ecological processes like herbivory, predation and pollination is needed. Arthropods play an important role in the high-arctic ecosystem and this role is determined by their density and activity. However, density and activity may be sensitive to separate components of climate. Earlier emergence due to advanced timing of snowmelt following climate change may expose adult arthropods to unchanged temperatures but higher levels of radiation. The capture rate of arthropods in passive open traps like pitfall trap integrates density and activity and, therefore, serves as a proxy of the magnitude of such arthropod-related ecological processes. We used arthropod pitfall trapping data and weather data from 10 seasons in high-arctic Greenland to identify climatic effects on the activity pattern of nine arthropod taxa. Results We were able to statistically separate the variation in capture rates into a non-linear component of capture date (density) and a linear component of weather (activity). The non-linear proxy of density always accounted for more of the variation than the linear component of weather. After accounting for the seasonal phenological development, the most important weather variable influencing the capture rate of flying arthropods was temperature, while surface-dwelling species were principally influenced by solar radiation. Conclusion Consistent with previous findings, air temperature best explained variation in the activity level of flying insects. An advancement of the phenology in this group due to earlier snowmelt will make individuals appear earlier in the season, but parallel temperature increases could mean that individuals are exposed to similar temperatures. Hence, the effect of climatic changes on the activity pattern in this group may be unchanged. In contrast, we found that solar radiation is a better proxy of activity levels than air temperature in surface-dwelling arthropods. An advancement of the phenology may expose surface-dwelling arthropods to higher levels of solar radiation, which suggest that their locomotory performance is enhanced and their contribution to ecological processes is increased. PMID:18454856

Høye, Toke T; Forchhammer, Mads C

2008-01-01

231

Seasonal changes in Titan's weather patterns and the evolution and implications of accompanying surface changes  

NASA Astrophysics Data System (ADS)

Post-equinox changes in Titan's atmospheric circulation brought clouds and extensive methane rain to low latitudes [1,2]. Observations by Cassini ISS over the ensuing ~1.5 yr revealed surface changes to be short-lived; few rain-darkened areas persisted through 2011. In an unsaturated permeable medium, infiltration rates are >20 mm/week [3], so persistence of surface liquids over several months suggests that either an impermeable layer or the local methane table lies close to the surface. Evaporation rates >1 mm/week are predicted at low latitudes [4] and 20 mm/week has been documented at Titan's poles [5], thus areas where darkening persisted must be saturated ground at the level of a methane table or have had ponded liquid 2.5-50 cm deep. Several smaller areas of surface brightening were also observed, a phenomenon that is less well understood. Cassini VIMS spectra of these regions do not match clouds or other surface units [6]. Interpretations include cleaning by runoff [2] or deposition of a fine-grained volatile solid as the result of evaporative cooling of the surface [6]. In general, brightening has persisted longer than darkening, but these areas are also reverting to their original appearance, possibly due to evaporation/sublimation of the bright material or re-deposition of darker hydrocarbons by aeolian transport or precipitation from the atmosphere. Cassini and Earth-based observers monitor Titan frequently, but few clouds have been observed since Fall 2010, which may indicate that enough methane was removed from the atmosphere and the lapse rate stabilized sufficiently that activity will not resume until the onset of convection at mid-northern latitudes later in northern spring. A similar lapse followed a 2004 outburst of south-polar clouds [7], which also appeared to produce significant rainfall [8]. [1] Turtle et al., GRL 38, L03203, doi:10.1029/2010GL046266, 2011. [2] Turtle et al., Science 331, 10.1126/science.1201063. 2011. [3] Hayes et al., GRL 35, L09204, 2008. [4] Schneider et al., Nature 481, doi:10.1038/nature10666, 2012. [5] Hayes et al., Icarus 211, 2011. [6] Barnes et al., LPSC XXXXIII, 2012. [7] Schaller et al., Icarus 184, 2006. [8] Turtle et al., GRL 36, L02204, doi:10.1029/2008GL036186, 2009.

Turtle, Elizabeth; McEwen, Alfred

2012-07-01

232

Quaternary environment change in Taiwan: the typhoon events observation by weather data in mountainous region  

NASA Astrophysics Data System (ADS)

Typhoons events are classic extreme events, and due to the location, Taiwan has high probability been hit by typhoons. About the occurrence and intensity of typhoons, they are related with quaternary environment change. To know the change about typhoons and how it relating to environment change, that is an important topic in Taiwan. In addition, there is another index of environment change: temperature. Temperature is very sensitive, if there has environment changes, it's very easy to see the temperature becomes hot or cold. Especially in mountainous region, without human interference, the data is more easily to show environment changes. This study uses the weather data from weather station at mountain Ali, because the environment in mountain is more sensitive than in urban. We will collect all historical typhoon rainfall data from 1960, and ranking the data with 3 years, 5 years, 10 years, 20 years, to find the trend of typhoons from short to long period. Second, we will do the same things about temperature data, finding its own trend. Third, comparing the trends of rainfall and temperature data, then see if they have relation or not.

Cheng, Yeuan Chang; Chung Lin, Jiun; Jen, Chia Hung

2010-05-01

233

Frost Monitoring and Forecasting Using MODIS Land Surface Temperature Data and a Numerical Weather Prediction Model Forecasts for Eastern Africa  

NASA Technical Reports Server (NTRS)

Frost is a major challenge across Eastern Africa, severely impacting agricultural farms. Frost damages have wide ranging economic implications on tea and coffee farms, which represent a major economic sector. Early monitoring and forecasting will enable farmers to take preventive actions to minimize the losses. Although clearly important, timely information on when to protect crops from freezing is relatively limited. MODIS Land Surface Temperature (LST) data, derived from NASA's Terra and Aqua satellites, and 72-hr weather forecasts from the Kenya Meteorological Service's operational Weather Research Forecast model are enabling the Regional Center for Mapping of Resources for Development (RCMRD) and the Tea Research Foundation of Kenya to provide timely information to farmers in the region. This presentation will highlight an ongoing collaboration among the Kenya Meteorological Service, RCMRD, and the Tea Research Foundation of Kenya to identify frost events and provide farmers with potential frost forecasts in Eastern Africa.

Kabuchanga, Eric; Flores, Africa; Malaso, Susan; Mungai, John; Sakwa, Vincent; Shaka, Ayub; Limaye, Ashutosh

2014-01-01

234

Surface analysis and anti-graffiti behavior of a weathered polyurethane-based coating embedded with hydrophobic nano silica  

NASA Astrophysics Data System (ADS)

In this study, a permanent anti-graffiti polyurethane coating was prepared using concomitant loading of an OH-functional silicone modified polyacrylate additive ranging from 2 to 15 mol% and hydrophobic silica nanoparticles from 1 to 5 wt%. UV-visible spectroscopy, contact angle measurement and dynamic mechanical thermal analysis (DMTA) analysis were conducted on selected samples to study the weathering performance of samples containing various amounts of silica nanoparticles before and after accelerated weathering conditions. The results showed that higher amounts of additive had inferior effects on the anti-graffiti performance of the coating samples after exposure. However, silica nanoparticles could positively affect the anti-graffiti performance against ageing cycles. This improvement was attributed to lower degradation of samples containing silica nanoparticles and barrier property of nanoparticles against graffiti penetration. The presence of silica nanoparticles did not have any significant effect on the surface free energy of the samples prior and after ageing.

Rabea, A. Mohammad; Mohseni, M.; Mirabedini, S. M.; Tabatabaei, M. Hashemi

2012-03-01

235

IRAC Observations of Weather and Tidal Heating on Gliese 436 b  

NASA Astrophysics Data System (ADS)

We propose to use IRAC at 8 microns to observe eight successive secondary eclipses of the P=2.644d, Neptune-mass planet that transits the red dwarf star Gliese 436. Initial measurements of the Gliese 436b secondary transits suggested that the planet's high (e=0.15) eccentricity is generating signficant tidal luminosity. The eccentric orbit of the planet will lead to 83-percent variations in received flux over the course of half an orbit. Additionally, the planet will be rotating pseudo-synchronously, with a spin period P ~2.3 days that is significantly less than the orbital period. These factors will contribute to interesting global flow patterns on the planetary surface. Our hydrodynamical model predicts a sinusoidal time-dependent flux variation of amplitude 0.00012 and period ~ 3 days. By measuring the 8-micron flux at successive secondary transits, we will detect this oscillation, and obtain a data set that can be compared with both our model as well as models being developed by other workers in the field. In addition, our flux measurements can be averaged to obtain an improved estimate of the planet's tidal luminosity. This quantity allows us to derive a tidal quality factor, Q, which in turn gives important clues to the interior structure of this remarkable planet.

Laughlin, Gregory; Deming, Drake; Langton, Jonathan

2008-03-01

236

Two Rare Northern Entoloma Species Observed in Sicily under Exceptionally Cold Weather Conditions  

PubMed Central

The biology and ecology of many Entoloma species is still poorly known as well as their geographical distribution. In Italy, there are no studies on the influence of weather on fungal abundance and richness and our knowledge on the ecology and distribution of Entoloma species needs to be improved. The discovery of two Entoloma species in Sicily (southern Italy), reported in the literature as belonging to the habitat of north European countries, was the basis leading to the assumption that anomalous climatic conditions could stimulate the growth of northern entolomas in the southernmost Mediterranean regions. The results of this study show that the presence of northern Entoloma species in Sicily is not influenced by the Mediterranean type of vegetation, by edaphic or altitudinal factors but by anomalous climatic trends of precipitations and temperatures which stimulate the fructification of basidiomata in correspondence with a thermal shock during autumn. PMID:22645481

Venturella, Giuseppe; Saitta, Alessandro; Mandracchia, Gerlando; Gargano, Maria Letizia

2012-01-01

237

Evaluating the Impacts of NASA/SPoRT Daily Greenness Vegetation Fraction on Land Surface Model and Numerical Weather Forecasts  

NASA Technical Reports Server (NTRS)

The NASA Short-term Prediction Research and Transition (SPoRT) Center has developed a Greenness Vegetation Fraction (GVF) dataset, which is updated daily using swaths of Normalized Difference Vegetation Index data from the Moderate Resolution Imaging Spectroradiometer (MODIS) data aboard the NASA EOS Aqua and Terra satellites. NASA SPoRT began generating daily real-time GVF composites at 1-km resolution over the Continental United States (CONUS) on 1 June 2010. The purpose of this study is to compare the National Centers for Environmental Prediction (NCEP) climatology GVF product (currently used in operational weather models) to the SPoRT-MODIS GVF during June to October 2010. The NASA Land Information System (LIS) was employed to study the impacts of the SPoRT-MODIS GVF dataset on a land surface model (LSM) apart from a full numerical weather prediction (NWP) model. For the 2010 warm season, the SPoRT GVF in the western portion of the CONUS was generally higher than the NCEP climatology. The eastern CONUS GVF had variations both above and below the climatology during the period of study. These variations in GVF led to direct impacts on the rates of heating and evaporation from the land surface. In the West, higher latent heat fluxes prevailed, which enhanced the rates of evapotranspiration and soil moisture depletion in the LSM. By late Summer and Autumn, both the average sensible and latent heat fluxes increased in the West as a result of the more rapid soil drying and higher coverage of GVF. The impacts of the SPoRT GVF dataset on NWP was also examined for a single severe weather case study using the Weather Research and Forecasting (WRF) model. Two separate coupled LIS/WRF model simulations were made for the 17 July 2010 severe weather event in the Upper Midwest using the NCEP and SPoRT GVFs, with all other model parameters remaining the same. Based on the sensitivity results, regions with higher GVF in the SPoRT model runs had higher evapotranspiration and lower direct surface heating, which typically resulted in lower (higher) predicted 2-m temperatures (2-m dewpoint temperatures). Portions of the Northern Plains states experienced substantial increases in convective available potential energy as a result of the higher SPoRT/MODIS GVFs. These differences produced subtle yet quantifiable differences in the simulated convective precipitation systems for this event.

Bell, Jordan R.; Case, Jonathan L.; LaFontaine, Frank J.; Kumar, Sujay V.

2012-01-01

238

Seasonal changes in Titan's weather patterns and the evolution and implications of accompanying surface changes  

NASA Astrophysics Data System (ADS)

Post-equinox changes in Titan's atmospheric circulation brought clouds and extensive methane rain to Titan's low latitudes [1,2]. Observations by Cassini ISS over the ~2 years since the storm revealed most of the changes to be short-lived; only a few darkened patches persisted through Fall 2011. In an unsaturated permeable medium, infiltration rates exceed 20 mm/week [3], so persistence of surface liquids over several months suggests either a shallow impermeable layer or that the local methane table lies close to the surface. Evaporation rates greater than 1 mm/week are predicted in equatorial regions [4] and rates of 20 mm/week have been documented at Titan's poles [5], thus areas where darkening persisted must be saturated ground at the level of a methane table or have had liquid ponded to depths of 2.5-50 cm. Several smaller areas of surface brightening were also observed, a phenomenon that is less well understood. Cassini VIMS spectra of these regions do not match those of clouds or other surface units [6, 7]. Interpretations include cleaning by runoff [2] or deposition of a fine-grained volatile solid as the result of evaporative cooling [6, 7]. In general, brightening has persisted longer than darkening, but these areas are also reverting to their original appearance, which could constrain rates of evaporation/sublimation of the bright material or re-deposition of darker hydrocarbons by aeolian transport or precipitation from the atmosphere. Cassini and Earth-based observers monitor Titan frequently (typically at least a few times per month), but few clouds have been observed since Fall 2010, which may indicate that enough methane was removed from the atmosphere and the lapse rate stabilized sufficiently that activity will not resume until the onset of convection at mid-northern latitudes later in northern spring. A similar lapse followed a 2004 outburst of south-polar clouds [8], which also appeared to produce significant rainfall [9]. [1] Turtle et al., GRL 38, L03203, doi:10.1029/2010GL046266, 2011. [2] Turtle et al., Science 331, 10.1126/science.1201063. 2011. [3] Hayes et al., GRL 35, L09204, 2008. [4] Schneider et al., Nature 481, doi:10.1038/nature10666, 2012. [5] Hayes et al., Icarus 211, 2011. [6] Barnes et al., LPSC XXXXIII, 2012. [7] Barnes et al., in revision. [8] Schaller et al., Icarus 184, 2006. [9] Turtle et al., GRL 36, L02204, doi:10.1029/2008GL036186, 2009.

Turtle, E. P.; Perry, J.; McEwen, A. S.; Barbara, J. M.; Del Genio, A. D.; West, R. A.; Barnes, J. W.; Hayes, A.; Lorenz, R. D.; Lunine, J. I.; Stofan, E. R.; Schaller, E. L.; Lopes, R. M.; Ray, T. L.

2012-12-01

239

Yellowstone Weather  

NSDL National Science Digital Library

Yellowstone National Park's high altitude and mountainous terrain makes weather prediction very difficult. This website provides seasonal weather information, average temperature and precipitation data, links to weather forecasts, and other weather links.

Yellowstone National Park

240

Cassini ISS observations of seasonal changes in Titan's meteorology and surface features (Invited)  

NASA Astrophysics Data System (ADS)

Since Cassini's arrival at Saturn the season has progressed from northern winter to just past the northern vernal equinox (the equivalent of ~mid-January to late March on Earth), driving changes in the weather patterns. Until shortly after Cassini arrived at Saturn, large convective cloud systems were common over the South Pole. Since 2005, such storms have been less common and elongated streaks of clouds have been observed further and further to the north, becoming common at high northern latitudes by 2007. Cassini's Imaging Science Subsystem (ISS) has also observed changes in surface features at high southern latitudes: a new large dark area appeared between July 2004 and June 2005 and may have subsequently faded; recent observations of Ontario Lacus suggest that its boundary may have receded somewhat as well. Such changes are interpreted to be the result of precipitation and ponding of liquid methane and the subsequent evaporation thereof. Intriguingly, Cassini RADAR observations of areas near Titan's south pole reveal far fewer lakes than are observed by RADAR at high northern latitudes and fewer than suggested by the number of dark features observed by ISS in this area. This apparent discrepancy may simply be a result of the fact that not all dark features identified by ISS are liquid-filled; however another possible explanation is that evaporation has occurred between the ISS observations in mid-2005 and RADAR observations of similar territory starting in 2007. Further investigation of comparison of ISS and RADAR observations is underway to better understand the implications of the differences observed. We will present observations of Titan's atmospheric behavior and surface features, documenting changes that have resulted from weather and seasonal change.

Turtle, E. P.; Perry, J.; McEwen, A. S.; Barbara, J.; Del Genio, A. D.; West, R. A.; Hayes, A. G.

2009-12-01

241

Evaluation of beryllium surface defects observed following chemical milling  

Microsoft Academic Search

Surface defects referred to as protrusions and depressions were observed on parts made from commercial quality beryllium after chemical milling. Surface defects referred to as a depression, mottling, and pitting were observed on parts made from 35 ksi yield strength beryllium after chemical milling. This paper summarizes the results of the metallographic and tensile testing performed to characterize the surface

Ferrera

1985-01-01

242

Evolution of Titan's equinoctial weather patterns and accompanying surface changes and implications thereof  

NASA Astrophysics Data System (ADS)

Post-equinox changes in Titan's atmospheric circulation brought clouds and extensive methane rain to Titan's low latitudes [1,2]. Observations by Cassini ISS over the ~1.5 years since the storm revealed most of the changes to be short-lived; only a few darkened patches persisted through Fall 2011. In an unsaturated permeable medium, infiltration rates are >20 mm/week [3], so persistence of surface liquids over several months suggests either a shallow impermeable layer or that the local methane table lies close to the surface. Evaporation rates >1 mm/week are predicted in equatorial regions [4] and rates of 20 mm/week have been documented at the poles [5], thus areas where darkening persisted must be saturated ground at the level of a methane table or have had liquid ponded to depths of 2.5-50 cm. Several smaller areas of surface brightening were also observed, a phenomenon that is less well understood. Cassini VIMS spectra of these regions do not match those of clouds or other surface units [6, 7]. Interpretations include cleaning by runoff [2] or deposition of fresh methane ice [6, 7]. In general, brightening has persisted longer than darkening, but these areas are also reverting to their original appearance, which could constrain the rate of re-deposition of darker hydrocarbon materials by aeolian transport or possibly precipitation of aerosols from the atmosphere. Although we monitor Titan frequently (at least a few times per month), little cloud activity has been observed since Fall 2010. This lack of clouds may indicate that the outbreak removed enough methane from the atmosphere and the lapse rate stabilized sufficiently that activity will not resume until the onset of convection at mid-northern latitudes later in northern spring. A similar lapse followed a large outbreak of south-polar clouds in Fall 2004 [8], which also appeared to produce significant rainfall [9]. References: [1] Turtle et al., GRL 38, L03203, doi: 10.1029/2010GL046266, 2011. [2] Turtle et al., Science 331, p. 1414, 10.1126/science.1201063. 2011. [3] Hayes et al., GRL 35, L09204, 2008. [4] Schneider et al., Nature 481, doi:10.1038/nature10666, 2012. [5] Hayes et al., Icarus 211, p. 655, 2011. [6] Barnes et al., LPSC XXXXIII, 2012. [7] Barnes et al., Titan Through Time, 3-5 April 2012. [8] Schaller et al., Icarus 184, p. 517, 2006. [9] Turtle et al., GRL 36, L02204, doi:10.1029/ 2008GL036186, 2009.

Turtle, E. P.; Perry, J. E.; Barnes, J. W.; McEwen, A. S.; Barbara, J. M.; Del Genio, A. D.; Hayes, A. G.; West, R. A.; Lorenz, R. D.; Schaller, E. L.; Lunine, J. I.; Ray, T. L.; Lopes, R. M. C.; Stofan, E. R.

2012-04-01

243

OBSERVATIONS OF LAND SURFACE PASSIVE MICROWAVE POLARIMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

The launch of WindSat and potential designs of future operational passive microwave sensors such as Conical Scanning Microwave Imager/Scanner (CMIS) have prompted an examination of what additional information about land surface features may be present in the 3rd and 4th Stokes parameters beyond the ...

244

Natural weathering mechanisms of almandine garnet  

NASA Astrophysics Data System (ADS)

The weathering of almandine garnet in the oxidized, vadose zone of saprolite near Otto, North Carolina, begins at grain boundaries and along fractures traversing the garnet grains. Radially oriented fibrous intergrowths of gibbsite and goethite form layers of uniform thickness, which grow by centripetal replacement as weathering proceeds. The contact between the garnet surface and the layer of weathering products is sharp and smooth, and garnet corners are rounded. Large, well-defined etch pits are absent on the underlying garnet surface. These observations suggest that diffusion (transport) of reactants and/or products through the gibbsite-goethite layer is the rate-limiting step in the weathering of almandine garnet in the oxidizing environment of the saprolite. In soils overlying the saprolite, garnet surfaces are directly exposed to weathering solutions without the intervening surface layer. Such “unprotected” grains in soils (and stream sediments) exhibit numerous large, well-developed etch pits. Surface-reaction control, rather than transport control, prevails during weathering of almandine garnet in the absence of protective surface layers of weathering products. Biochemical or biological processes in the soil apparently prevent the gibbsite-goethite layer from forming or persisting. Soil solutions can therefore react directly with the garnet surface, rather than requiring reactants or products to diffuse through the gibbsite-goethite coating as in the saprolite. The mechanism, and rate-limiting step, of almandine garnet weathering is apparently strongly dependent on the chemical environment in which weathering occurs. *Present address: Department of Geological Sciences, Michigan State University, East Lansing, Michigan 48824-1115

Velbel, Michael Anthony

1984-10-01

245

Deeply weathered basement rocks in Norway  

NASA Astrophysics Data System (ADS)

Recent studies show that, in addition to tectonic processes, surface processes have also had a profound impact on the topography of Norway. This is especially obvious for the northernmost part of the Nordland county and for western Norway, where the current immature Alpine-type topography cannot be easily explained by tectonic processes only. Erosion of the sedimentary succession also does not seem sufficient to explain the observed relief. Common remnants of deeply weathered basement rocks, however, indicate a history of deep alteration and later erosion of the bedrock, which needs to be considered as another important factor in the development of the topographic relief. Most of the sites with deeply weathered basement exhibit a clay-poor grussy type of weathering, which is generally considered to be of relatively young age (Plio-/Pleistocene) and thought to represent an intermediate stage of weathering. Unfortunately, small amounts or complete absence of clay minerals in these weathering products precluded the accurate dating of this weathered material. Scandinavia was exposed to a large range of glaciations and the once extensive sedimentary successions have been almost entirely eroded, which impedes a minimum age estimate of the weathering profile. Although several sites preserving remnants of deep weathering can still be observed onshore Norway, they are all covered by Quaternary overburden and the age of the regolith remains thus unconstrained and a matter of debate. The only exception is a small Mesozoic basin on Andøya, northern Norway, where weathered and clay-poor saprolite was found underlying Jurassic and Cretaceous sedimentary rocks. Over the last few years the Geological Survey of Norway (NGU) has mapped and investigated deep weathering onshore Norway to better understand weathering processes and to constrain the age of the weathering remnants. The combined interpretation of geophysical, mineralogical and geochemical data, together with recent observations from the Norwegian shelf, where grussy type of weathered bedrock was found buried under Mesozoic sediments, leads to the conclusion that coarse-grained, clay-poor saprolite does not necessarily indicate a young age of weathering but could in fact be of Early Mesozoic age or even older. The Late Jurassic to Early Cretaceous faults in the Lofoten-Vesterålen area are for instance little affected by weathering processes. With the goal to refine our understanding of the complex weathering processes and to constrain them in time, the NGU is establishing a new K-Ar laboratory for the dating and characterization of illite grown authigenically in the saprolites. It is expected that the data generated therein will contribute new quantitative constraints to the long-lasting debate as to the age of weathering processes in Scandinavia.

Bönner, Marco; Knies, Jochen; Fredin, Ola; Olesen, Odleiv; Viola, Giulio

2014-05-01

246

Observations of Ultracool dwarfs with ULTRACAM on the VLT: a search for weather  

E-print Network

We present multi-colour photometry of four field ultracool dwarfs with the triple-beam photometer ultracam. Data were obtained simultaneously in the Sloan-g' band and a specially designed narrow-band NaI filter. The previously reported 1.8-hr period of Kelu-1 is here recovered in the g'-band, but the lack of any significant variability in the NaI light of this object precludes any conclusion as to the cause of the variability. 2MASS 2057-0252 and DENIS 1441-0945 show no convincing evidence for variability. 2MASS 1300+1912, on the other hand, shows good evidence for gradual trends in both bands at the 5% level. These trends are anti-correlated at a high level of significance, a result which is incompatible with models of starspot-induced variability. It would seem likely that dust cloud "weather" is responsible for the short-term variability in this object.

S. P. Littlefair; V. S. Dhillon; T. R. Marsh; T. Shahbaz; E. L. Martin

2006-05-09

247

Rainfall forecasting in a mountainous region using a weather radar and ground meteorological observations  

NASA Astrophysics Data System (ADS)

Weather radars provide several types of information useful for defining the state and evolution of a rain system: the rainfall rate, the vertically integrated rainwater content, and the advection velocity. The very short-term rainfall forecasting models dedicated to the survey of catchments (particularly those subject to flash-floods) are typically designed to include one or more of these information types. A general formulation of these models associating an advective term and a dynamical term is proposed by Lee and Georgakakos (1991). The model proposed in this work extends the simplified dynamical formulation developed by Seo and Smith (1992) and French and Krajewski (1994) by explicitly accounting for orographic enhancement and by combining the dynamical component with an advection-diffusion scheme (Smolarkiewicz 1983). This paper presents an initial evaluation of the model for two rain events in the mountainous Cevennes region located in the South of France. One-hour and two-hour lead-time forecasts for four catchments are performed and compared with two simple methods: persistence and advection.

Dolciné, L.; Andrieu, H.; French, M. N.

248

The Role of Model and Initial Condition Error in Numerical Weather Forecasting Investigated with an Observing System Simulation Experiment  

NASA Technical Reports Server (NTRS)

A series of experiments that explore the roles of model and initial condition error in numerical weather prediction are performed using an observing system simulation experiment (OSSE) framework developed at the National Aeronautics and Space Administration Global Modeling and Assimilation Office (NASA/GMAO). The use of an OSSE allows the analysis and forecast errors to be explicitly calculated, and different hypothetical observing networks can be tested with ease. In these experiments, both a full global OSSE framework and an 'identical twin' OSSE setup are utilized to compare the behavior of the data assimilation system and evolution of forecast skill with and without model error. The initial condition error is manipulated by varying the distribution and quality of the observing network and the magnitude of observation errors. The results show that model error has a strong impact on both the quality of the analysis field and the evolution of forecast skill, including both systematic and unsystematic model error components. With a realistic observing network, the analysis state retains a significant quantity of error due to systematic model error. If errors of the analysis state are minimized, model error acts to rapidly degrade forecast skill during the first 24-48 hours of forward integration. In the presence of model error, the impact of observation errors on forecast skill is small, but in the absence of model error, observation errors cause a substantial degradation of the skill of medium range forecasts.

Prive, Nikki C.; Errico, Ronald M.

2013-01-01

249

Introduction to Space Weather  

NASA Astrophysics Data System (ADS)

Adverse space weather is one of the principal threats to modern human technology. Solar coronal mass ejections, large solar flares, and high-speed solar wind streams often lead to sequences of damaging disturbances within the Earth's magnetosphere, in the atmosphere, and even on the Earth's surface. Powerful and long-lasting geomagnetic storms can develop following solar disturbances and enhancements of the highly relativistic electron populations throughout the outer terrestrial radiation zone can also result. High-energy protons and heavier ions arriving in near-earth space - or trapped in the magnetosphere and having clearest effect in the South Atlantic Anomaly (SAA) - can damage satellite solar power panels, confuse optical trackers, and deposit harmful charges into sensitive electronic components. Recent international space science programs have made a concerted effort to study activity on the Sun, the propagation of energy bursts from the Sun to near-Earth space, energy coupling into the magnetosphere, and its redistribution and deposition in the upper and middle atmosphere. Extreme solar, geomagnetic and solar wind conditions can be observed by a large array of international satellites and ground-based sensors. Many types of space weather-related problems have been identified in recent years. This chapter presents examples of space weather-induced anomalies and failures and discusses community efforts to propose technical and operational solutions to space weather problems now and in the future.

Baker, Daniel N.

250

Space Weathering of Rocks  

NASA Technical Reports Server (NTRS)

Space weathering discussions have generally centered around soils but exposed rocks will also incur the effects of weathering. On the Moon, rocks make up only a very small percentage of the exposed surface and areas where rocks are exposed, like central peaks, are often among the least space weathered regions we find in remote sensing data. However, our studies of weathered Ap 17 rocks 76015 and 76237 show that significant amounts of weathering products can build up on rock surfaces. Because rocks have much longer surface lifetimes than an individual soil grain, and thus record a longer history of exposure, we can study these products to gain a deeper perspective on the weathering process and better assess the relative impo!1ance of various weathering components on the Moon. In contrast to the lunar case, on small asteroids, like Itokowa, rocks make up a large fraction of the exposed surface. Results from the Hayabusa spacecraft at Itokowa suggest that while the low gravity does not allow for the development of a mature regolith, weathering patinas can and do develop on rock surfaces, in fact, the rocky surfaces were seen to be darker and appear spectrally more weathered than regions with finer materials. To explore how weathering of asteroidal rocks may differ from lunar, a set of ordinary chondrite meteorites (H, L, and LL) which have been subjected to artificial space weathering by nanopulse laser were examined by TEM. NpFe(sup 0) bearing glasses were ubiquitous in both the naturally-weathered lunar and the artificially-weathered meteorite samples.

Noble, Sarah

2011-01-01

251

Climate, weather, and north polar observations from the Mars Reconnaissance Orbiter Mars Color Imager  

Microsoft Academic Search

The Mars Reconnaissance Orbiter observes Mars from a nearly circular, polar orbit. From this vantage point, the Mars Color Imager extends the ?5 Mars years record of Mars Global Surveyor global, visible-wavelength multi-color observations of meteorological events and adds measurements at three additional visible and two ultraviolet wavelengths. Observations of the global distribution of ozone (which anti-correlates with water vapor)

Michael C. Malin; Wendy M. Calvin; Bruce A. Cantor; R. Todd Clancy; Robert M. Haberle; Philip B. James; Peter C. Thomas; Michael J. Wolff; James F. Bell; Steven W. Lee

2008-01-01

252

Climate, weather, and north polar observations from the Mars Reconnaissance Orbiter Mars Color Imager  

Microsoft Academic Search

The Mars Reconnaissance Orbiter observes Mars from a nearly circular, polar orbit. From this vantage point, the Mars Color Imager extends the ˜5 Mars years record of Mars Global Surveyor global, visible-wavelength multi-color observations of meteorological events and adds measurements at three additional visible and two ultraviolet wavelengths. Observations of the global distribution of ozone (which anti-correlates with water vapor)

Michael C. Malin; Wendy M. Calvin; Bruce A. Cantor; R. Todd Clancy; Robert M. Haberle; Philip B. James; Peter C. Thomas; Michael J. Wolff; James F. Bell; Steven W. Lee

2008-01-01

253

Do spaceborne aerosol observations limit the accuracy of modeled surface solar irradiance?  

NASA Astrophysics Data System (ADS)

play a primary role in the global climate system and the solar radiation budget at the Earth surface. Here we analyze the role of spaceborne aerosol observations and their uncertainties in the expected accuracy of the modeled cloudless surface shortwave downward radiation using a state-of-the-art numerical weather prediction model over the continental U.S. We compare five different modeling approaches for the aerosol optical effects with differing sophistication. Overall, we show that, counterintuitively, the direct and diffuse irradiances predicted by solar radiation models that use empirically adjusted fixed aerosol extinction may be more accurate than more sophisticated radiative transfer models that require inputs of aerosols. We conclude that, compared to ground observations, the mean absolute error in satellite-retrieved aerosol optical depth over the U.S., and possibly elsewhere, should be reduced to less than 0.025 aerosol optical depth unit to assure improvement over the predictions of a simpler, aerosol-insensitive radiation model.

Ruiz-Arias, José A.; Gueymard, Christian A.; Santos-Alamillos, Francisco J.; Pozo-Vázquez, David

2015-01-01

254

Observation and modelling of stable isotopes in precipitation for midlatitude weather systems in Melbourne, Australia  

Microsoft Academic Search

The application of stable water isotopes as tracers of moisture throughout the hydrological cycle is often hindered by the relatively coarse temporal and spatial resolution of observational data. Intensive observation periods (IOPs) of isotopes in precipitation have been valuable in this regard enabling the quantification of the effects of vapour recycling, convection, cloud top height and droplet reevaporation (Dansgaard, 1953;

Vaughan Barras; Ian Simmonds

2010-01-01

255

Observations of electrons at the lunar surface  

Microsoft Academic Search

Observations of electrons at the Apollo 12 and 15 sites by the Alsep Solar Wind Spec- trometer experiments showed qualitative differehces. In the geomagnetic tail the Apollo 15 instrument provided measurements of lunar photoelectron flux from 5 to 40 eV; at 20 eV the flux was 2 X 106 el.\\/cm a sec eV ster. The estimated height-integrated conductivity of th

Bruce E. Goldstein

1974-01-01

256

Age calibration of weathering fractures in desert clasts: A new approach to dating geomorphic surfaces in arid landscapes  

NASA Astrophysics Data System (ADS)

Advances in geomorphological and sedimentological research depend on the availability of reliable exposure age constraints. Establishing robust age models at a high spatial and temporal resolution is crucial for measuring rates of geomorphological change and decoding complex landscapes shaped by time-dependent forces, e.g. climate fluctuations. A number of isotopic and luminescence techniques are now available for dating geomorphic surfaces, however they remain expensive and time-consuming to deploy with detailed coverage over space and time in many study areas. For this reason, quick and accessible methods for correlating and extrapolating these chronologies are needed. In arid landscapes, among others, a variety of weathering-induced changes occur to geomorphic and sedimentary surfaces, and many of these processes occur at predictable rates and can be quantified using objective, field based measurements. One example is the gradual widening of fractures that exist within boulders on desert surfaces, by a combination of processes including salt weathering and freeze-thaw cycles. The recent emergence of very detailed exposure age models in a number of locations means it is now possible to measure the rates of desert weathering processes, and use them as fully calibrated age indicators themselves. With the potential to significantly extend the coverage of existing age constraints, this kind of quantitative age correlation would enable a broad range of geomorphological and sedimentological research that depends on detailed absolute age models. We have measured the mean widths of hundreds of vertical fractures that dissect granitic boulders, on a variety of alluvial surfaces in Owens Valley, California, which have themselves been independently dated in detail using cosmogenic nuclides. Our data demonstrates for the first time that these fractures widen at a predictable, steady rate of approximately 1 mm ka-1 for at least the last 150 ka, in this arid study area in the south-western United States. This finding, which is repeatable at a number of test sites, allows clast fracture widths to be exploited as a simple and powerful technique for the inexpensive dating of geomorphic surfaces in the field. We introduce a robust statistical method for this new approach to exposure dating, perform a full uncertainty analysis on its results, and discuss the potential usefulness of this technique in other arid landscapes.

D'Arcy, Mitch; Roda Boluda, Duna; Whittaker, Alex

2014-05-01

257

Plasmon switching: Observation of dynamic surface plasmon steering by  

E-print Network

Plasmon switching: Observation of dynamic surface plasmon steering by selective mode excitation a plasmon steering method that enables us to dynamically control the direction of surface plasmons generated surface plasmons are launched can be controlled. Experiments confirm that it is possible to distribute

Visser, Taco D.

258

Observed and CAM3 GCM Sea Surface Wind  

E-print Network

Observed and CAM3 GCM Sea Surface Wind Speed Distributions: Characterization, Comparison, and Bias climatological surface wind speed probability density functions (PDFs) estimated from observations and use them to evaluate, for the first time, contemporaneous wind PDFs predicted by a GCM. The ob- servations include NASA

Zender, Charles

259

Comparison of Historical CMIP5 Surface Temperatures to the Berkeley Earth Gridded Observational Temperature Field  

NASA Astrophysics Data System (ADS)

The Berkeley Earth surface temperature research program uses observations from nearly 40,000 weather stations to reconstruct monthly land-surface temperature fields over a longer duration (250 years) and with higher resolution than other comparable global efforts. This submission will compare and contrast the observation-based Berkeley Earth temperature fields to the land component of historical CMIP5 climate model temperature fields. Emphasis will be given to examining long-term trends and spatial variations in climate response. Though the models all broadly reproduce the historical warming of the last 150 years, we observe numerous differences among them. When compared to observations, many models overpredict warming at high northern latitudes and underpredict warming at mid northern latitudes. Similarly, most models predict a greater surface temperature response to volcanic eruptions than has been observed. By using these and other comparisons between models and observations, it is possible to identify both strengths and weaknesses in the current generation of models. It is hoped that such comparisons can help guide the development of the next generation of models. In addition, identifying models that are relatively more accurate in reproducing the climate change of the historical period may also suggest which models might be more reliable in their predictions of future climate change. The implications for constraining climate sensitivity will be discussed.

Rohde, R. A.; Mosher, S.; Hausfather, Z.

2013-12-01

260

Solid Surface Combustion Experiment Yields Significant Observations  

NASA Technical Reports Server (NTRS)

The spread of a flame over solid fuel is not only a fundamental textbook combustion phenomenon, but also the central element of destructive fires that cause tragic loss of life and property each year. Throughout history, practical measures to prevent and fight fires have been developed, but these have often been based on lessons learned in a costly fire. Since the 1960 s, scientists and engineers have employed powerful tools of scientific research to understand the details of flame spread and how a material can be rendered nonflammable. High-speed computers have enabled complex flame simulations, whereasand lasers have provided measurements of the chemical composition, temperature, and air velocities inside flames. The microgravity environment has emerged as the third great tool for these studies. Spreading flames are complex combinations of chemical reactions and several physical processes including the transport of oxygen and fuel vapor to the flame and the transfer of heat from the flame to fresh fuel and to the surroundings. Depending on its speed, air motion in the vicinity of the flame can affect the flame in substantially different ways. For example, consider the difference between blowing on a campfire and blowing out a match. On Earth, gravity induces air motion because of buoyancy (the familiar rising hot gases); this process cannot be controlled experimentally. For theoreticians, buoyant air motion complicates the problem modeling of flame spread beyond the capacity of modern computers to simulate. The microgravity environment provides experimental control of air motion near spreading flames, with results that can be compared with detailed theory. The Solid Surface Combustion Experiment (SSCE) was designed to obtain benchmark flame spreading data in quiescent test atmospheres--the limiting case of flames spreading. Professor Robert Altenkirch, Vice President for Research at Mississippi State University, proposed the experiment concept, and the NASA Lewis Research Center designed, built, and tested the SSCE hardware. It was the first microgravity science experiment built by Lewis for the space shuttle and the first combustion science experiment flown in space.

Sacksteder, Kurt R.; Koudelka, John M.; Vergilii, Franklin

1999-01-01

261

Annual carbon dioxide cycle in a montane soil: observations, modeling, and implications for weathering  

Microsoft Academic Search

Profiles of COâ concentrations in soil and snow, soil respiration, soil and snow temperatures, and shallow ground water chemistry were monitored from March 1984 to July 1985 in a montane region neat Brighton, Utah. Significant seasonal variations in the concentrations of COâ in soil and snow occurred, and two principal rise-decline cycles were observed. During the first cycle the concentration

D. Kip Solomon; Thure E. Cerling

1987-01-01

262

Plot-scale observations of snow surface roughness (Invited)  

NASA Astrophysics Data System (ADS)

The snow surface is the interface between the atmosphere and the snowpack, and the characteristics of its roughness influences the movement of air. This roughness interface can be observed at different scales. While the influence of crystal morphology is important to the micro-scale features, it likely does not alter the surface-atmosphere interaction. Measurements of snow surface roughness have been taken at the crystal scale using digital photography and at the vegetation scale using snow depth probes combined with survey equipment. This paper illustrates i) techniques to assess snow surface roughness, and ii) the overlapping scales of variability between snow surface depth through topography, as related to snow surface roughness.

Fassnacht, S. R.

2010-12-01

263

Doppler weather radar observations of the 2009 eruption of Redoubt Volcano, Alaska  

USGS Publications Warehouse

The U.S. Geological Survey (USGS) deployed a transportable Doppler C-band radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska that provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data captured during the Redoubt eruption. The MiniMax 250-C (MM-250C) radar detected seventeen of the nineteen largest explosive events between March 23 and April 4, 2009. Sixteen of these events reached the stratosphere (above 10 km) within 2–5 min of explosion onset. High column and proximal cloud reflectivity values (50 to 60 dBZ) were observed from many of these events, and were likely due to the formation of mm-sized accretionary tephra-ice pellets. Reflectivity data suggest that these pellets formed within the first few minutes of explosion onset. Rapid sedimentation of the mm-sized pellets was observed as a decrease in maximum detection cloud height. The volcanic cloud from the April 4 explosive event showed lower reflectivity values, due to finer particle sizes (related to dome collapse and related pyroclastic flows) and lack of significant pellet formation. Eruption durations determined by the radar were within a factor of two compared to seismic and pressure-sensor derived estimates, and were not well correlated. Ash dispersion observed by the radar was primarily in the upper troposphere below 10 km, but satellite observations indicate the presence of volcanogenic clouds in the stratosphere. This study suggests that radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions.

Schneider, David J.; Hoblitt, Richard P.

2013-01-01

264

Understanding midlatitude space weather: Storm impacts observed at Bear Lake Observatory on 31 March 2001  

Microsoft Academic Search

On 30 March 2001 in the late evening an auroral display was observed over the United States of America. The Bear Lake Observatory (BLO) magnetometer in Utah measured changes of 550 nT in less than 30 min. During the same period, BLO ionosonde measurements showed deep high-frequency radio wave absorption up to 7 MHz. BLO's GPS single-frequency receiver experienced geolocation

J. J. Sojka; D. Rice; J. V. Eccles; F. T. Berkey; P. Kintner; W. Denig

2004-01-01

265

Winter Weather  

MedlinePLUS

... Matters What's New A - Z Index Disasters & Severe Weather Earthquakes Extreme Heat Floods Hurricanes Landslides Tornadoes Tsunamis Volcanoes Wildfires Winter Weather Winter Weather Language: English Español (Spanish) Recommend on Facebook Tweet ...

266

Weather Watch  

ERIC Educational Resources Information Center

Suggests a number of ways in which Federal Aviation Agency weather report printouts can be used in teaching the weather section of meteorology. These weather sequence reports can be obtained free of charge at most major airports. (JR)

Bratt, Herschell Marvin

1973-01-01

267

Coastal Observations of Weather Features in Senegal during the AMMA SOP-3 Period  

NASA Technical Reports Server (NTRS)

During 15 August through 30 September 2006, ground and aircraft measurements were obtained from a multi-national group of students and scientists in Senegal. Key measurements were aimed at investigating and understanding precipitation processes, thermodynamic and dynamic environmental conditions, cloud, aerosol and microphysical processes and spaceborne sensors (TRMM, CloudSat/Calipso) validation. Ground and aircraft instruments include: ground based polarimetric radar, disdrometer measurements, a course and a high-density rain gauge network, surface chemical measurements, a 10 m flux tower, broadband IR, solar and microwave measurements, rawinsonde and radiosonde measurements, FA-20 dropsonde, in situ microphysics and cloud radar measurements. Highlights during SOP3 include ground and aircraft measurements of squall lines, African Easterly Waves (AEWs), Saharan Air Layer advances into Senegal, and aircraft measurements of AEWs -- including the perturbation that became Hurricane Isaac.

Jenkins, G.; Kucera, P.; Joseph, E.; Fuentes, J.; Gaye, A.; Gerlach, J.; Roux, F.; Viltard, N.; Papazzoni, M.; Protat, A.; Bouniol, D.; Reynolds, A.; Arnault, J.; Badiane, D.; Kebe, F.; Camara, M.; Sall, S.

2009-01-01

268

Studying geoeffective interplanetary coronal mass ejections between the Sun and Earth: Space weather implications of Solar Mass Ejection Imager observations  

NASA Astrophysics Data System (ADS)

Interplanetary coronal mass ejections (ICMEs) are the primary cause of severe space weather at Earth because they drive shocks and trigger geomagnetic storms that can damage spacecraft and ground-based systems. The Solar Mass Ejection Imager (SMEI) is a U. S. Air Force experiment with the ability to track ICMEs in white light from near the Sun to Earth and beyond, thus providing an extended observational range for forecasting storms. We summarize several studies of SMEI's detection and tracking capability, especially of the ICMEs associated with the intense (peak Dst ? -100 nT) geomagnetic storms that were the focus of the NASA Living With a Star Geostorm Coordinated Data Analysis Workshop. We describe the SMEI observations and analyses for the 18 intense storms observed from May 2003-2007 with adequate SMEI coverage and identified solar and interplanetary source regions. SMEI observed the associated ICMEs for 89% of these intense storms. For each event we extracted the time differences between these sets of times at 1 AU for shock arrival time, predicted ICME arrival time, onset of high-altitude aurora observed by SMEI, and storm onset. The mean intervals between successive pairs of these data were found to each be ˜4 hours. On average, SMEI first detected the geoeffective ICME about 1 day in advance, yielding a prediction lead time of ˜18 hours. Finally, the RMS values for the ICME-shock and storm-ICME time differences were determined, and provide at least a 1-hour improvement compared to similar observational and model-dependent studies.

Webb, D. F.; Howard, T. A.; Fry, C. D.; Kuchar, T. A.; Mizuno, D. R.; Johnston, J. C.; Jackson, B. V.

2009-05-01

269

Surface Plasmon Lasing Observed in Metal Hole Arrays  

NASA Astrophysics Data System (ADS)

Surface plasmons in metal hole arrays have been studied extensively in the context of extraordinary optical transmission, but so far these arrays have not been studied as resonators for surface plasmon lasing at optical frequencies. We experimentally study a metal hole array with a semiconductor (InGaAs) gain layer placed in close (20 nm) proximity of the metal hole array. As a function of increasing pump power, we observe an intense and spectrally narrow peak, with a clear threshold. This laser emission is donut shaped and radially polarized. Three experimental observations support that the system shows surface plasmon lasing. First, the full wavelength dispersion of the observed resonances can be understood by using a single surface plasmon mode of the system. Second, the polarization of these resonances is as expected for surface plasmons. Third, the magnitude of the avoided crossing, which results from mode coupling at the holes, has a similar magnitude as found in simulations using surface plasmons.

van Beijnum, Frerik; van Veldhoven, Peter J.; Geluk, Erik Jan; de Dood, Michiel J. A.; 't Hooft, Gert W.; van Exter, Martin P.

2013-05-01

270

Weather Stations: Phase Change  

NSDL National Science Digital Library

In this activity, learners observe the water cycle in action! Water vapor in a tumbler condenses on chilled aluminum foil — producing the liquid form of water familiar to us as rain and dew. Learners discuss how Jupiter's lack of a surface simplifies its water cycle. Learners then consider the roles ammonia and ammonia compounds play in Jupiter's more complicated atmosphere. This activity is one station that can be combined with other stations for an hour and half lesson on weather patterns on Jupiter and Earth.

2014-07-11

271

Cosmic weather and cybernetics  

NASA Astrophysics Data System (ADS)

The use of computer techniques to study cosmic weather (i.e., manifestations of solar activity in near-earth space, the ionosphere, and the lower atmosphere) is examined. A scheme of observational facilities for the acquisition of data on cosmic weather is described; the basic types of observations that yield information on the state of the ionosphere at different altitudes are considered; and the role of computers in the prediction of cosmic weather is assessed.

Avdiushin, Sergei Ivanovich; Danilov, Aleksei Dmitrievich; Dlikman, Fishel'l'vovich

1987-09-01

272

The Surface Composition and Temperature of Asteroid 21 Lutetia As Observed by Rosetta/VIRTIS  

NASA Astrophysics Data System (ADS)

The Visible, InfraRed, and Thermal Imaging Spectrometer (VIRTIS) on Rosetta obtained hyperspectral images, spectral reflectance maps, and temperature maps of the asteroid 21 Lutetia. No absorption features, of either silicates or hydrated minerals, have been detected across the observed area in the spectral range from 0.4 to 3.5 micrometers. The surface temperature reaches a maximum value of 245 kelvin and correlates well with topographic features. The thermal inertia is in the range from 20 to 30 joules meter-2 kelvin-1 second-0.5, comparable to a lunarlike powdery regolith. Spectral signatures of surface alteration, resulting from space weathering, seem to be missing. Lutetia is likely a remnant of the primordial planetesimal population, unaltered by differentiation processes and composed of chondritic materials of enstatitic or carbonaceous origin, dominated by iron-poor minerals that have not suffered aqueous alteration.

Coradini, A.; Capaccioni, F.; Erard, S.; Arnold, G.; De Sanctis, M. C.; Filacchione, G.; Tosi, F.; Barucci, M. A.; Capria, M. T.; Ammannito, E.; Grassi, D.; Piccioni, G.; Giuppi, S.; Bellucci, G.; Benkhoff, J.; Bibring, J. P.; Blanco, A.; Blecka, M.; Bockelee-Morvan, D.; Carraro, F.; Carlson, R.; Carsenty, U.; Cerroni, P.; Colangeli, L.; Combes, M.; Combi, M.; Crovisier, J.; Drossart, P.; Encrenaz, E. T.; Federico, C.; Fink, U.; Fonti, S.; Giacomini, L.; Ip, W. H.; Jaumann, R.; Kuehrt, E.; Langevin, Y.; Magni, G.; McCord, T.; Mennella, V.; Mottola, S.; Neukum, G.; Orofino, V.; Palumbo, P.; Schade, U.; Schmitt, B.; Taylor, F.; Tiphene, D.; Tozzi, G.

2011-10-01

273

The surface composition and temperature of asteroid 21 Lutetia as observed by Rosetta/VIRTIS.  

PubMed

The Visible, InfraRed, and Thermal Imaging Spectrometer (VIRTIS) on Rosetta obtained hyperspectral images, spectral reflectance maps, and temperature maps of the asteroid 21 Lutetia. No absorption features, of either silicates or hydrated minerals, have been detected across the observed area in the spectral range from 0.4 to 3.5 micrometers. The surface temperature reaches a maximum value of 245 kelvin and correlates well with topographic features. The thermal inertia is in the range from 20 to 30 joules meter(-2) kelvin(-1) second(-0.5), comparable to a lunarlike powdery regolith. Spectral signatures of surface alteration, resulting from space weathering, seem to be missing. Lutetia is likely a remnant of the primordial planetesimal population, unaltered by differentiation processes and composed of chondritic materials of enstatitic or carbonaceous origin, dominated by iron-poor minerals that have not suffered aqueous alteration. PMID:22034430

Coradini, A; Capaccioni, F; Erard, S; Arnold, G; De Sanctis, M C; Filacchione, G; Tosi, F; Barucci, M A; Capria, M T; Ammannito, E; Grassi, D; Piccioni, G; Giuppi, S; Bellucci, G; Benkhoff, J; Bibring, J P; Blanco, A; Blecka, M; Bockelee-Morvan, D; Carraro, F; Carlson, R; Carsenty, U; Cerroni, P; Colangeli, L; Combes, M; Combi, M; Crovisier, J; Drossart, P; Encrenaz, E T; Federico, C; Fink, U; Fonti, S; Giacomini, L; Ip, W H; Jaumann, R; Kuehrt, E; Langevin, Y; Magni, G; McCord, T; Mennella, V; Mottola, S; Neukum, G; Orofino, V; Palumbo, P; Schade, U; Schmitt, B; Taylor, F; Tiphene, D; Tozzi, G

2011-10-28

274

Observation of Fermi arc surface states in a topological metal.  

PubMed

The topology of the electronic structure of a crystal is manifested in its surface states. Recently, a distinct topological state has been proposed in metals or semimetals whose spin-orbit band structure features three-dimensional Dirac quasiparticles. We used angle-resolved photoemission spectroscopy to experimentally observe a pair of spin-polarized Fermi arc surface states on the surface of the Dirac semimetal Na3Bi at its native chemical potential. Our systematic results collectively identify a topological phase in a gapless material. The observed Fermi arc surface states open research frontiers in fundamental physics and possibly in spintronics. PMID:25593189

Xu, Su-Yang; Liu, Chang; Kushwaha, Satya K; Sankar, Raman; Krizan, Jason W; Belopolski, Ilya; Neupane, Madhab; Bian, Guang; Alidoust, Nasser; Chang, Tay-Rong; Jeng, Horng-Tay; Huang, Cheng-Yi; Tsai, Wei-Feng; Lin, Hsin; Shibayev, Pavel P; Chou, Fang-Cheng; Cava, Robert J; Hasan, M Zahid

2015-01-16

275

Space Weathering of Lunar Rocks  

NASA Technical Reports Server (NTRS)

All materials exposed at the lunar surface undergo space weathering processes. On the Moon, boulders make up only a small percentage of the exposed surface, and areas where such rocks are exposed, like central peaks, are often among the least space weathered regions identified from remote sensing data. Yet space weathered surfaces (patina) are relatively common on returned rock samples, some of which directly sample the surface of larger boulders. Because, as witness plates to lunar space weathering, rocks and boulders experience longer exposure times compared to lunar soil grains, they allow us to develop a deeper perspective on the relative importance of various weathering processes as a function of time.

Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

2012-01-01

276

SEM and TEM Observation of the Surfaces of the Fine-Grained Particles Retrieved from the Muses-C Regio on the Asteroid 25413 Itokawa  

NASA Technical Reports Server (NTRS)

Surface materials on airless solar system bodies exposed to interplanetary space are gradually changed their visible to near-infrared reflectance spectra by the process called "space weathering", which makes the spectra darker and redder. Hapke et al. proposed a model of space weathering: vapor deposition of nanophase reduced iron (npFe(sup 0)) on the surfaces of the grains within the very surface of lunar regolith. This model has been proved by detailed observation of the surfaces of the lunar soil grains by transmission electron microscope (TEM). They demonstrated that npFe(sup 0) was formed by a combination of vapor deposition and irradiation effects. In other words, both micrometeorite impacts and irradiation by solar wind and galactic cosmic ray play roles on the space weathering on the Moon. Because there is a continuum of reflectance spectra from those of Q-type asteroids (almost the same as those of ordinary chondrites) to those of S-type asteroids, it is strongly suggested that reflectance spectra of asteroids composed of ordinary chondrite-like materials were modified over time to those of S-type asteroids due to space weathering. It is predicted that a small amount of npFe(sup 0) on the surface of grains in the asteroidal regolith composed of ordinary chondrite-like materials is the main agent of asteroidal space weathering.

Noguchi, T.; Nakamura, T.; Zolensky, Michael E.; Tanaka, M.; Hashimoto, T.; Konno, M.; Nakato, A.; Ogami, T.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

2011-01-01

277

External Resource: Erosion and Weathering  

NSDL National Science Digital Library

This is a Teachers' Domain photo essay with images that depict surface features on Earth that result from weathering and erosion, as well as measures designed to mitigate their unwanted effects. Topics: weathering, erosion, sediments, dunes, deltas, glaci

1900-01-01

278

Observation of Fermi surface deformation in a dipolar quantum gas  

NASA Astrophysics Data System (ADS)

In the presence of isotropic interactions, the Fermi surface of an ultracold Fermi gas is spherical. Introducing anisotropic interactions can deform the Fermi surface, but the effect is subtle and challenging to observe experimentally. Here, we report on the observation of a Fermi surface deformation in a degenerate dipolar Fermi gas of erbium atoms. The deformation is caused by the interplay between strong magnetic dipole-dipole interaction and the Pauli exclusion principle. We demonstrate the many-body nature of the effect and its tunability with the Fermi energy. Our observation provides a basis for future studies on anisotropic many-body phenomena in normal and superfluid phases.

Aikawa, K.; Baier, S.; Frisch, A.; Mark, M.; Ravensbergen, C.; Ferlaino, F.

2014-09-01

279

Observational and theoretical studies of the evolving structure of baroclinic waves: Attractor dynamics of global weather systems  

NASA Technical Reports Server (NTRS)

Significant progress was made in developing a six-component dry model of mid-latitude baroclinic wave evolution, and a ten-component moist model. These models include representations of airflow over mountians and non-adiabatic processes. As a first step, the properties of a reduced, three component, baroclinic system are studied. The classical baroclinic stability criteria emerge as the properties of one of the three equilibria admitted, with the remaining two equilibria forming the attractor region for the observed weather activity. Passive tracer evolution in a baroclinic wave was studied. A model in which only constituents trapped within low atmospheric levels are considered, has been extended to include the possibility for fluxes into the upper levels of the atmosphere. The reported results for the lower levels achieved previously are shown to be qualitatively similar to those obtained by these new calculations in which the vertical flux constraint is removed. An extensive study of an 8-year record of global outgoing longwave radiation for the Northern Hemisphere reveals that blocking events exhibit only a weak signature of blocking highs, as measured by relatively low values of the ratio of the standard deviation to the mean value of the observed long wave outgoing radiation. Though present in many cases, the signature is not a strongly distinctive feature of the blocking episodes.

Saltzman, B.; Hansen, A. R.; Nagle, R. N.; Tang, C. M.

1985-01-01

280

Site characterization summary report for dry weather surface water sampling upper East Fork Poplar Creek characterization area Oak Ridge Y-12 Plant, Oak Ridge, Tennessee  

SciTech Connect

This report describes activities associated with conducting dry weather surface water sampling of Upper East Fork Poplar Creek (UEFPC) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. This activity is a portion of the work to be performed at UEFPC Operable Unit (OU) 1 [now known as the UEFPC Characterization Area (CA)], as described in the RCRA Facility Investigation Plan for Group 4 at the Oak- Ridge Y-12 Plant, Oak Ridge, Tennessee and in the Response to Comments and Recommendations on RCRA Facility Investigation Plan for Group 4 at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, Volume 1, Operable Unit 1. Because these documents contained sensitive information, they were labeled as unclassified controlled nuclear information and as such are not readily available for public review. To address this issue the U.S. Department of Energy (DOE) published an unclassified, nonsensitive version of the initial plan, text and appendixes, of this Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) Plan in early 1994. These documents describe a program for collecting four rounds of wet weather and dry weather surface water samples and one round of sediment samples from UEFPC. They provide the strategy for the overall sample collection program including dry weather sampling, wet weather sampling, and sediment sampling. Figure 1.1 is a schematic flowchart of the overall sampling strategy and other associated activities. A Quality Assurance Project Plan (QAPJP) was prepared to specifically address four rounds of dry weather surface water sampling and one round of sediment sampling. For a variety of reasons, sediment sampling has not been conducted and has been deferred to the UEFPC CA Remedial Investigation (RI), as has wet weather sampling.

NONE

1996-08-01

281

Understanding the assimilation of dual-polarimetric radar observations and their impact on convective weather forecasting in mesoscale models  

NASA Astrophysics Data System (ADS)

Dual-polarimetric radars typically transmit/receive both horizontally and vertically polarized radio wave pulses. Owing to the enhanced measurement, dual-pol Doppler variables can provide more information about the liquid and solid cloud and precipitation particles, hence obtain more accurate estimate of rainfall and hydrometeors than non-polarimetric weather radars. The assimilation of dual-pol radar data may be a potential way to improve the performance of short-term forecast of numerical models. At present, not much effort has been given into the dual-pol radar data assimilation research field. With the ongoing upgrade of the current U.S. NEXRAD radar network to include dual-polarimetric capabilities, the dual-pol radar network will cover the whole country within the next couple years. The time is upon us to begin exploring how to best use the polarimetric data to improve forecast of severe storm and forecast initialization. The assimilation of dual-pol data for real cases is a challenging work. In this study, high-resolution (~1 km) WRF model and its 3DVAR data assimilation system are used. The dual-polarimetric radar data used in our studies was collected by the C-band Advanced Radar for Meteorological and Operational Research (ARMOR) radar (located at Huntsville International Airport (34.6804N, 86.7743W)), yet the emphasis now is toward using S-Band data from the upgraded NEXRAD network. Our presentation will highlight our recent work on assimilating the ARMOR radar data for real case convective storms, as well as new work using S-Band observations. Details of the methodology of data assimilation, the influences of different dual-pol variables on model initial condition and on the short-term prediction of precipitation, and the results for the real case storms, will be presented. In addition, before including a new observing system in an assimilation system, (dual-pol observations in this case) it is important to first assess the information content and uncertainty of the observations and forward model. An estimate of the information content in a set of observations requires knowledge of the relationship between measurements and forward observations. If the range of possible values of the measurements and forward observations is represented as a probability distribution, then the information content can be computed from the joint probability density function of the forward observations conditioned on the set of available measurements and on whatever forward model is chosen to relate them. Preliminary results will be shown toward understanding the information content of dual-polarimetric radar observations and their relationship to WRF model physics uncertainty.

Li, X.; Mecikalski, J. R.; Posselt, D. J.

2011-12-01

282

Climatological characteristics of fronts in the western North Pacific based on surface weather charts  

NASA Astrophysics Data System (ADS)

Composite front climatology in the western North Pacific is determined using a newly developed 1.0° gridded data set. Here we propose a research strategy for determining the spatiotemporal distribution of fronts using weather chart images published by the Japan Meteorological Agency, one of the major data providers in the region. A preliminarily investigation of the internal data characteristics for the period of 2000-2010 is undertaken, and the final 4 years of data are used for an analysis of front climatology to avoid the effect of any spurious trends. This enables in-depth analyses to be conducted, which have not previously been possible in the region, including the composites of cross-sectional patterns for the thermal fields and precipitation near fronts, front length seasonality, and the significance of the thermal gradient near the fronts, in addition to determining the frontal frequency and spatial distribution of frontal precipitation. Pixel-wise analysis reveals that 56% of the local precipitation maximum is located on the warm side of a cold front caused by less tilted upward motion on the warm side, with the intrusion of the upper level cold dry air into the warm side. This new data set also enables a further analysis of the occluded fronts, which are not correctly distinguished in the existing objective detection method.

Utsumi, Nobuyuki; Kim, Hyungjun; Seto, Shinta; Kanae, Shinjiro; Oki, Taikan

2014-08-01

283

Modeling the dry-weather tidal cycling of fecal indicator bacteria in surface waters of an intertidal wetland.  

PubMed

Recreational water quality at beaches in California and elsewhere is often poor near the outlets of rivers, estuaries, and lagoons. This condition has prompted interest in the role of wetlands in modulating surface water concentrations of fecal indicator bacteria (FIB), the basis of water quality standards internationally. A model was developed and applied to predict the dry-weather tidal cycling of FIB in Talbert Marsh, an estuarine, intertidal wetland in Huntington Beach, California, in response to loads from urban runoff, bird feces, and resuspended sediments. The model predicts the advection, dispersion and die-off of total coliform, Escherichia coli, and enterococci using a depth-integrated formulation. We find that urban runoff and resuspension of contaminated wetland sediments are responsible for surface water concentrations of FIB in the wetland. Model predictions show that urban runoff controls surface water concentrations at inland sites and sediment resuspension controls surface water concentrations near the mouth. Direct wash-off of bird feces into the surface water is not a significant contributor, although bird feces can contribute to the sediment bacteria load. The key parameters needed to accurately predict FIB concentrations, using a validated hydrodynamic model, are: the load due to urban runoff, sediment erodibility parameters, and sediment concentrations and surface water die-off rates of enteric bacteria. In the present study, literature values for sediment erodibility and water column die-off rates are used and average concentrations of FIB are predicted within 1/2 log unit of measurements. Total coliform are predicted more accurately than E. coli or enterococci, both in terms of magnitude and tidal variability. Since wetland-dependent animals are natural sources of FIB, and FIB survive for long periods of time and may multiply in wetland sediments, these results highlight limitations of FIB as indicators of human fecal pollution in and near wetlands. PMID:16051310

Sanders, Brett F; Arega, Feleke; Sutula, Martha

2005-09-01

284

Shortwave surface radiation budget network for observing small-scale cloud inhomogeneity fields  

NASA Astrophysics Data System (ADS)

As part of the High Definition Clouds and Precipitation for advancing Climate Prediction Observational Prototype Experiment (HOPE), a high spatial density network of 99 silicon photodiode pyranometers was set up around Jülich (10 km x 12 km area) from April to July 2013, to capture the variability in the radiation field at the surface induced by small-scale cloud inhomogeneity. Each of these autonomously operated pyranometer stations was equipped with weather sensors for simultaneous measurements of ambient air temperature and relative humidity. In this paper, we provide the details of this unique setup of the pyranometer network and the data analysis with initial quality screening procedure we adopted. We also present some exemplary cases consisting of the days with clear, broken cloudy and overcast skies to assess our spatio-temporal observations from the network, and validate their consistency with other collocated radiation measurements available during the HOPE period.

Madhavan, B. L.; Kalisch, J.; Macke, A.

2015-03-01

285

Spectroscopic analyses of Fe and water in clays: A Martian surface weathering study  

NASA Technical Reports Server (NTRS)

Martian surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the Martian surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic studies of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification.

Bishop, J. L.; Pieters, Carle M.; Edwards, J. O.; Coyne, L. M.; Chang, S.

1991-01-01

286

Greenland surface albedo changes 1981-2012 from satellite observations  

Technology Transfer Automated Retrieval System (TEKTRAN)

Significant melt over Greenland has been observed during the last several decades associated with extreme warming events over the northern Atlantic Ocean. An analysis of surface albedo change over Greenland is presented, using a 32-year consistent satellite albedo product from the Global Land Surfac...

287

Sea Surface Height Variability Observed by Pressure-recording Inverted  

E-print Network

Sea Surface Height Variability Observed by Pressure-recording Inverted Echo Sounders and Satellite echo sounders (PIESs) 7 moored profilers 48 profiling floats 1 moored surface buoy (KEO buoy) #12;03/07/08 Park/URI 3 PIES (Pressure-recording Inverted Echo Sounder) Emits 12 kHz sound pulses Measures - round

Rhode Island, University of

288

Observed twentieth century land surface air temperature and precipitation covariability  

E-print Network

consequences [IPCC, 2001]. Rising SATs and changes in precipitation patterns, phases, and intensity will affect temperatures (SATs) and precipitation were observed over 71% and 27%, respectively, of the global land surface annual values of SAT and precipitation exist over 24% of the global land surface. Regional

Dery, Stephen

289

Severe Weather  

ERIC Educational Resources Information Center

Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This article deals with a poster entitled, "Severe Weather," that has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in…

Forde, Evan B.

2004-01-01

290

Severe Weather  

ERIC Educational Resources Information Center

Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This month's insert, Severe Weather, has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in this poster are hurricanes,…

Forde, Evan B.

2004-01-01

291

Weather Forecasting  

NSDL National Science Digital Library

Students consider how weather forecasting plays an important part in their daily lives. They learn about the history of weather forecasting — from old weather proverbs to modern forecasting equipment — and how improvements in weather technology have saved lives by providing advance warning of natural hazards.

2014-09-18

292

Next Generation Weather Lab  

NSDL National Science Digital Library

Users can learn about weather data output and analysis at the Next Generation Weather Lab website. This expansive website provides an abundance of surface data and upper air data as well as satellite and radar images for the United States. Types of data include plotting maps, contoured images, soundings, and cross sections.

293

UM Weather  

NSDL National Science Digital Library

Sponsored by The Weather Underground at the University of Michigan at Ann Arbor, UM Weather bills itself as the "Internet's premier source of weather information." The site offers several general audience tools such as the Fast Forecast for any city in the US, ski weather, and weather cams. But, it also provides access to over two dozen weather software packages, a new computer model forecasts page, and most impressively a list of close to 400 other weather related Web sites. Professionals and researchers will appreciate the non-technical feel of the site and the valuable information they can procure from it.

294

BBC Weather  

NSDL National Science Digital Library

At this website, the BBC offers an array of materials dealing with weather. Meteorologists can discover employment opportunities. Individuals with spectacular photographs of weather phenomenon can submit their images to the photo gallery. Students and educators can find introductory materials on basic weather concepts, forecasting, extreme events, and broadcasting the weather. The website offers fun weather-related games and projects, a meteorology glossary, and links to other educational websites.

295

Winter Weather  

NSDL National Science Digital Library

This project explores factors that help create severe winter weather. An interactive simulation provides hands-on experience, followed by guiding questions and resource exploration. Weather affects our everyday lives. Some days it's sunny and some days its not. The years weather is split up into seasons. 1. What are the four seasons? 2. What kind of weather do you see in the summer? 3. What kind of weather is unique to winter? 4. ...

Mrs. Bellows

2009-09-28

296

Weather and climate  

NASA Technical Reports Server (NTRS)

Recommendations for using space observations of weather and climate to aid in solving earth based problems are given. Special attention was given to: (1) extending useful forecasting capability of space systems, (2) reducing social, economic, and human losses caused by weather, (3) development of space system capability to manage and control air pollutant concentrations, and (4) establish mechanisms for the national examination of deliberate and inadvertent means for modifying weather and climate.

1975-01-01

297

Sunspots, Space Weather and Climate  

NASA Technical Reports Server (NTRS)

Four hundred years ago this year the telescope was first used for astronomical observations. Within a year, Galileo in Italy and Harriot in England reported seeing spots on the surface of the Sun. Yet, it took over 230 years of observations before a Swiss amateur astronomer noticed that the sunspots increased and decreased in number over a period of about 11 years. Within 15 years of this discovery of the sunspot cycle astronomers made the first observations of a flare on the surface of the Sun. In the 150 years since that discovery we have learned much about sunspots, the sunspot cycle, and the Sun s explosive events - solar flares, prominence eruptions and coronal mass ejections that usually accompany the sunspots. These events produce what is called Space Weather. The conditions in space are dramatically affected by these events. Space Weather can damage our satellites, harm our astronauts, and affect our lives here on the surface of planet Earth. Long term changes in the sunspot cycle have been linked to changes in our climate as well. In this public lecture I will give an introduction to sunspots, the sunspot cycle, space weather, and the possible impact of solar variability on our climate.

Hathaway, David H.

2009-01-01

298

Weather Photography  

NSDL National Science Digital Library

Ph.D. student Harald Edens describes himself as a "photographer of lightning, clouds, atmospheric optical phenomena and astronomy". His Web site entitled Weather Photography proves this by providing a stunning collection of photographs and movies of atmospheric optics, lightning, clouds, and astronomy. The author describes how the photographs were taken, what equipment was used, and even discusses many of the phenomenon being observed such as mirages and halos. An added bonus of this very interesting site is that the author generously allows free personal use of the photographs.

299

Mountain Weather  

NSDL National Science Digital Library

Mountains can be awe-inspiring both for the vistas they provide and for the weather events and long-term climate systems they support. This interactive feature illustrates how a moisture-laden air mass interacts with a mountain slope to produce characteristic patterns of precipitation over the mountain and surrounding areas. Viewers can see how clouds and precipitation form as the air mass ascends the windward side of the peak, and observe the rain shadow created on the leeward side by the descending, warmed, and moisture-depleted air. A background essay and list of discussion questions supplement the interactive feature.

300

An assessment of buoy-derived and numerical weather prediction surface heat fluxes in the tropical Pacific  

NASA Astrophysics Data System (ADS)

As part of the Eastern Pacific Investigation of Climate Processes program, from 2000 through 2003, the easternmost 95°W Tropical Atmosphere Ocean (TAO) moorings were enhanced to provide time series of net surface heat flux, and the National Oceanic and Atmospheric Administration ship maintaining the 95°W and 110°W TAO lines was enhanced to monitor surface heat fluxes and atmospheric boundary layer structure. In this study we compare the ship-based and buoy-based radiative, bulk latent, and sensible heat fluxes, as well as the meteorological state variables used to compute the turbulent heat fluxes. The buoy net surface heat flux measurements appear to have an overall uncertainty near the target 10 W m-2, when careful attention is paid to the state variables. When hourly averaged data were unavailable, the telemetered daily averaged data were used in combination with an estimate of the mesoscale gustiness. In the eastern tropical Pacific a warm layer correction to account for stratification above 1-m depth was important only during the warm season (January-May) near the equator. These high-quality, cross-validated buoy heat flux time series are then used to assess the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), NCEP/Department of Energy, and 40-year European Centre for Medium-Range Weather Forecasts reanalyses' surface heat fluxes. All reanalyses show that over warm water where deep convection is prominent, latent heat loss is too large and net solar radiation is too weak; conversely, in regions of stratocumulus over cool water, net solar radiation is too strong, and for NCEP/NCAR, latent heat loss is too weak.

Cronin, Meghan F.; Fairall, Christopher W.; McPhaden, Michael J.

2006-06-01

301

Estimating long-term surface hydrological components by coupling remote sensing observation with surface flux model.  

SciTech Connect

A model framework for parameterized subgrid-scale surface fluxes (PASS) has been applied to use satellite data, models, and routine surface observations to infer root-zone available moisture content and evapotranspiration rate with moderate spatial resolution within Walnut River Watershed in Kansas. Biweekly composite normalized difference vegetative index (NDVI) data are derived from observations by National Oceanic and Atmospheric Administration (NOAA) satellites. Local surface observations provide data on downwelling solar irradiance, air temperature, relative humidity, and wind speed. Surface parameters including roughness length, albedo, surface water conductance, and the ratio of soil heat flux to net radiation are estimated; pixel-specific near-surface meteorological conditions such as air temperature, vapor pressure, and wind speed are adjusted according to local surface forcing. The PASS modeling system makes effective use of satellite data and can be run for large areas for which flux data do not exist and surface meteorological data are available from only a limited number of ground stations. The long-term surface hydrological budget is evaluated using radar-derived precipitation estimates, surface meteorological observations, and satellite data. The modeled hydrological components in the Walnut River Watershed compare well with stream gauge data and observed surface fluxes during 1999.

Song, J.; Wesely, M. L.

2002-05-02

302

Weather automation studies at the Otis Weather Test Facility  

Microsoft Academic Search

A description of the Otis Weather Test Facility (WTF) is presented, taking into account the distribution of surface-based and tower-mounted instrumentation at the WTF, the automation of the rotating beam ceilometer, the present weather decision tree, and slant visual range techniques. A demonstration model of a Modular Automated Weather System (MAWS) is also considered. The versatility of MAWS results from

D. A. Chisholm

1978-01-01

303

Surface Turbulent Fluxes Over Pack Ice Inferred from TOVS Observations  

NASA Technical Reports Server (NTRS)

A one-dimensional, atmospheric boundary layer model is coupled to a thermodynamic ice model to estimate the surface turbulent fluxes over thick sea ice. The principal forcing parameters in this time-dependent model are the air temperature, humidity, and wind speed at a specified level (either at 2 m or at 850 mb) and the downwelling surface radiative fluxes. The free parameters. are the air temperature, humidity, and wind speed profiles below the specified level, the surface skin temperature, the ice temperature profile, and the surface turbulent fluxes. The goal is to determine how well we can estimate the turbulent surface heat and momentum fluxes using forcing parameters from atmospheric temperatures and radiative fluxes retrieved from the TIROS-N Operational Vertical Sounder (TOVS) data. Meteorological observations from the Lead Experiment (LeadEx, April 1992) ice camp are used to validate turbulent fluxes computed with the surface observations and the results are used to compare with estimates based on radio-sonde observations or with estimates based on TOVS data. We find that the TOVS-based estimates of the stress are significantly more accurate than those found with a constant geostrophic drag coefficient, with a root-mean-square error about half as large. This improvement is due to stratification effects included in the boundary layer model. The errors in the sensible heat flux estimates, however, are large compared to the small mean values observed during the field experiment.

Lindsay, R. W.; Francis, J. A.; Persson, P. O. G.; Rothrock, D. A.; Schweiger, A. J.

1996-01-01

304

A scheme for computing surface layer turbulent fluxes from mean flow surface observations  

NASA Technical Reports Server (NTRS)

A physical model and computational scheme are developed for generating turbulent surface stress, sensible heat flux and humidity flux from mean velocity, temperature and humidity at some fixed height in the atmospheric surface layer, where conditions at this reference level are presumed known from observations or the evolving state of a numerical atmospheric circulation model. The method is based on coupling the Monin-Obukov surface layer similarity profiles which include buoyant stability effects on mean velocity, temperature and humidity to a force-restore formulation for the evolution of surface soil temperature to yield the local values of shear stress, heat flux and surface temperature. A self-contained formulation is presented including parameterizations for solar and infrared radiant fluxes at the surface. Additional parameters needed to implement the scheme are the thermal heat capacity of the soil per unit surface area, surface aerodynamic roughness, latitude, solar declination, surface albedo, surface emissivity and atmospheric transmissivity to solar radiation.

Hoffert, M. I.; Storch, J.

1978-01-01

305

Reconstructing CMEs with Coordinated Imaging and In Situ Observations: Global Structure, Kinematics, and Implications for Space Weather Forecasting  

NASA Astrophysics Data System (ADS)

We reconstruct the global structure and kinematics of coronal mass ejections (CMEs) using coordinated imaging and in situ observations from multiple vantage points. A forward modeling technique, which assumes a rope-like morphology for CMEs, is used to determine the global structure (including orientation and propagation direction) from coronagraph observations. We reconstruct the corresponding structure from in situ measurements at 1 AU with the Grad-Shafranov (GS) method, which gives the flux-rope orientation, cross section and a rough knowledge of the propagation direction. CME kinematics (propagation direction and radial distance) during the transit from the Sun to 1 AU are studied with a geometric triangulation technique, which provides an unambiguous association between solar observations and in situ signatures; a track fitting approach is invoked when data are available from only one spacecraft. We show how the results obtained from imaging and in situ data can be compared by applying these methods to some events, especially Earth-directed ones. This merged imaging and in situ study shows important consequences and implications for CME research as well as space weather forecasting: (1) CME propagation directions can be determined to a relatively good precision as shown by the consistency between different methods; (2) the geometric triangulation technique shows a promising capability to link solar observations with corresponding in situ signatures at 1 AU and to predict CME arrival at the Earth; (3) the flux rope within CMEs, which has the most hazardous southward magnetic field, cannot be imaged at large distances due to expansion; (4) the flux-rope orientation derived from in situ measurements at 1 AU may have a large deviation from that determined by coronagraph image modeling; (5) we find, for the first time, that CMEs undergo a westward migration with respect to the Sun-Earth line at their acceleration phase, which we suggest as a universal feature produced by the magnetic field connecting the Sun and ejecta. Importance of having dedicated spacecraft at L4 and L5, which are well situated for the triangulation concept, is also discussed based on the results.

Liu, Y.; Thernisien, A. F.; Luhmann, J. G.; Vourlidas, A.; Davies, J. A.; Lin, R. P.; Bale, S.

2010-12-01

306

Observations During GRIP from HIRAD: Ocean Surface Wind Speed and Rain Rate  

NASA Technical Reports Server (NTRS)

HIRAD (Hurricane Imaging Radiometer) flew on the WB-57 during NASA's GRIP (Genesis and Rapid Intensification Processes) campaign in August - September of 2010. HIRAD is a new C-band radiometer using a synthetic thinned array radiometer (STAR) technology to obtain cross-track resolution of approximately 3 degrees, out to approximately 60 degrees to each side of nadir. By obtaining measurements of emissions at 4, 5, 6, and 6.6 GHz, observations of ocean surface wind speed and rain rate can be inferred. This technique has been used for many years by precursor instruments, including the Stepped Frequency Microwave Radiometer (SFMR), which has been flying on the NOAA and USAF hurricane reconnaissance aircraft for several years. The advantage of HIRAD over SFMR is that HIRAD can observe a +/- 60-degree swath, rather than a single footprint at nadir angle. Results from the flights during the GRIP campaign will be shown, including images of brightness temperatures, wind speed, and rain rate. To the extent possible, comparisons will be made with observations from other instruments on the GRIP campaign, for which HIRAD observations are either directly comparable or are complementary. Potential impacts on operational ocean surface wind analyses and on numerical weather forecasts will also be discussed.

Miller, Timothy L.; James, M. W.; Jones, L.; Ruf, C. S.; Uhlhorn, E. W.; Bailey, M. C.; Buckley, C. D.; Simmons, D. E.; Johnstone, S.; Peterson, A.; Schultz, L. A.; Biewas, S.; Johnson, J. W.; Shah, G.; Feingstein, D.; Cleveland, W. H.; Johnson, J.; Hood, R. E.

2011-01-01

307

Constructing design weather data for future climates  

Microsoft Academic Search

We develop a method, here called ‘morphing’, to produce design weather data for building thermal simulations that accounts for future changes to climate. Morphing combines present-day observed weather data with results from climate models. The procedure yields weather time series that encapsulate the average weather conditions of future climate scenarios, whilst preserving realistic weather sequences. In this sense the method

SE Belcher; JN Hacker; DS Powell

2005-01-01

308

An observational correlation between stellar brightness variations and surface gravity.  

PubMed

Surface gravity is a basic stellar property, but it is difficult to measure accurately, with typical uncertainties of 25 to 50 per cent if measured spectroscopically and 90 to 150 per cent if measured photometrically. Asteroseismology measures gravity with an uncertainty of about 2 per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for more than 150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity: if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and root mean squared brightness variations on timescales of less than eight hours for stars with temperatures of 4,500 to 6,750?kelvin, log surface gravities of 2.5 to 4.5 (cgs units) and overall brightness variations of less than three parts per thousand. A straightforward observation of optical brightness variations therefore allows a determination of the surface gravity with a precision of better than 25 per cent for inactive Sun-like stars at main-sequence to giant stages of evolution. PMID:23969460

Bastien, Fabienne A; Stassun, Keivan G; Basri, Gibor; Pepper, Joshua

2013-08-22

309

Observations of Land Surface Variability Using Passive Microwave Sensing  

NASA Technical Reports Server (NTRS)

Understanding the global variability of land surface wetness (soil moisture), skin temperature, and related surface fluxes of heat and moisture is key to assessing the importance of the land surface in influencing climate. The feasibility of producing model estimates of these quantities is being studied as part of the International Satellite Land Surface Climatology Project (ISLSCP) Global Soil Wetness Project (GSWP). In the GSWP approach, meteorological observations and analyses are used to drive global circulation models. Satellite measurements can provide independent estimates of key land surface parameters that are needed for initializing and validating the climate models and for monitoring long-term change. Satellite observations of the land surface can also be assimilated into soil models to estimate moisture in the root zone. In our research, passive microwave satellite data recorded during 1978-1987 from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) are being used to examine spatial and temporal trends in surface soil moisture, vegetation, and temperature. These data include observations at C and X bands (6.6 and 10.7 GHz), which are not available on the current Special Sensor Microwave/Imager (SSM/I) and are precursors to data that will become available from the Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth Observing Satellite (ADEOS-II) and Earth Observing System (EOS) PM1 in the year 2000. A chart shows a time-series of SMMR-derived surface temperature, T-e and surface soil moisture M, retrieved on a 0.5 deg x 0.5 deg grid and further averaged over a 4 deg x 10 deg study region in the African Sahel. Also shown are National Center for Environmental Prediction (NCEP) model outputs of surface temperature, T-sfc, and soil wetness, Soil-w. The variables have been scaled to have similar dynamic ranges on the plots. The NCEP data from the NCEP Reanalysis Project are monthly averages on a 2.5 deg x 2.5 deg grid averaged over the 4 deg x 10 deg study area. Comparisons of SMMR retrievals with forecast model output show the potential of the satellite data for validating model output and monitoring long-term trends. Continuing work will extend these results to other regions to validate the retrievals more quantitatively. In preparation for the launch of AMSR, field experiments are planned in collaboration with the Global Energy and Water Cycle Experiment (GEWEX) Coordinated Enhanced Observing Period (CEOP) experiments to evaluate the satellite-derived soil moisture measurements and to demonstrate their usefulness for land surface hydrology and climate. Additional information is contained in the original.

Njoku, Eni G.

1999-01-01

310

Soil, snow, weather, and sub-surface storage data from a mountain catchment in the rain-snow transition zone  

NASA Astrophysics Data System (ADS)

A comprehensive hydroclimatic data set is presented for the 2011 water year to improve understanding of hydrologic processes in the rain-snow transition zone. This type of data set is extremely rare in scientific literature because of the quality and quantity of soil depth, soil texture, soil moisture, and soil temperature data. Standard meteorological and snow cover data for the entire 2011 water year are included, which include several rain-on-snow (ROS) events. Surface soil textures and soil depths from 57 points are presented as well as soil texture profiles from 14 points. Meteorological data include continuous hourly shielded, unshielded, and wind-corrected precipitation, wind speed and direction, air temperature, relative humidity, dew point temperature, and incoming solar and thermal radiation data. This data is often viewed as "forcing data", and is gap filled and serially complete. Sub-surface data included are hourly soil moisture data from multiple depths from seven soil profiles within the catchment, and soil temperatures from multiple depths from two soil profiles. Hydrologic response data include hourly stream discharge from the catchment outlet weir, continuous snow depths from one location, intermittent snow depths from 5 locations, and snow depth and density data from ten weekly snow surveys. Snow and hydrologic response data are meant to provide data on the catchment hydrologic response to the weather data. This data is mostly presented "as measured" although snow depths from one sensor and streamflow at the catchment outlet have been gap filled and are serially complete. Though the weather, snow, and hydrologic response data only covers one water year, the presentation of the additional subsurface data (soil depth, texture, moisture, and temperature) makes it one of the most detailed and complete hydro-climatic data sets from the climatically sensitive rain-snow transition zone. The data presented are appropriate for a wide range of modeling (energy balance snow modeling, soil capacitance parametric modeling, etc.) and descriptive studies. Data is available at doi:10.1594/PANGAEA.819837.

Kormos, P. R.; Marks, D.; Williams, C. J.; Marshall, H. P.; Aishlin, P.; Chandler, D. G.; McNamara, J. P.

2014-04-01

311

Lunar surface roughness derived from LRO Diviner Radiometer observations  

NASA Astrophysics Data System (ADS)

Sunlit and shaded slopes have a variety of temperatures based on their orientation with respect to the Sun. Generally, greater slope angles lead to higher anisothermality within the field of view. This anisothermality is detected by measuring changing emitted radiance as a function of viewing angle or by measuring the difference in brightness temperatures with respect to observation wavelength. Thermal infrared measurements from the Lunar Reconnaissance Orbiter Diviner Radiometer were used to derive lunar surface roughness via two observation types: (1) nadir multispectral observations with full diurnal coverage and (2) multiple emission angle targeted observations. Measurements were compared to simulated radiance from a radiative equilibrium thermal model and Gaussian slope distribution model. Nadir observations most closely match a 20° RMS slope distribution, and multiple emission angle observations can be modeled using 20-35° RMS slope distributions. Limited sampling of the lunar surface did not show any clear variation in roughness among surface units. Two-dimensional modeling shows that surfaces separated by distances greater than 0.5-5 mm can remain thermally isolated in the lunar environment, indicating the length scale of the roughness features. Non-equilibrium conditions are prevalent at night and near sunrise and sunset, preventing the use of the equilibrium thermal model for roughness derivations using data acquired at these local times. Multiple emission angle observations also show a significant decrease in radiance at high emission angles in both daytime and nighttime observations, and hemispherical emissivity is lower than is apparent from nadir observations. These observations and models serve as a basis for comparison with similar measurements of other airless bodies and as an initial template for the interpretation of TIR measurements acquired under a variety of geometric conditions.

Bandfield, Joshua L.; Hayne, Paul O.; Williams, Jean-Pierre; Greenhagen, Benjamin T.; Paige, David A.

2015-03-01

312

Estimating Long Term Surface Soil Moisture in the GCIP Area From Satellite Microwave Observations  

NASA Technical Reports Server (NTRS)

Soil moisture is an important component of the water and energy balances of the Earth's surface. Furthermore, it has been identified as a parameter of significant potential for improving the accuracy of large-scale land surface-atmosphere interaction models. However, accurate estimates of surface soil moisture are often difficult to make, especially at large spatial scales. Soil moisture is a highly variable land surface parameter, and while point measurements are usually accurate, they are representative only of the immediate site which was sampled. Simple averaging of point values to obtain spatial means often leads to substantial errors. Since remotely sensed observations are already a spatially averaged or areally integrated value, they are ideally suited for measuring land surface parameters, and as such, are a logical input to regional or larger scale land process models. A nine-year database of surface soil moisture is being developed for the Central United States from satellite microwave observations. This region forms much of the GCIP study area, and contains most of the Mississippi, Rio Grande, and Red River drainages. Daytime and nighttime microwave brightness temperatures were observed at a frequency of 6.6 GHz, by the Scanning Multichannel Microwave Radiometer (SMMR), onboard the Nimbus 7 satellite. The life of the SMMR instrument spanned from Nov. 1978 to Aug. 1987. At 6.6 GHz, the instrument provided a spatial resolution of approximately 150 km, and an orbital frequency over any pixel-sized area of about 2 daytime and 2 nighttime passes per week. Ground measurements of surface soil moisture from various locations throughout the study area are used to calibrate the microwave observations. Because ground measurements are usually only single point values, and since the time of satellite coverage does not always coincide with the ground measurements, the soil moisture data were used to calibrate a regional water balance for the top 1, 5, and 10 cm surface layers in order to interpolate daily surface moisture values. Such a climate-based approach is often more appropriate for estimating large-area spatially averaged soil moisture because meteorological data are generally more spatially representative than isolated point measurements of soil moisture. Vegetation radiative transfer characteristics, such as the canopy transmissivity, were estimated from vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and the 37 GHz Microwave Polarization Difference Index (MPDI). Passive microwave remote sensing presents the greatest potential for providing regular spatially representative estimates of surface soil moisture at global scales. Real time estimates should improve weather and climate modelling efforts, while the development of historical data sets will provide necessary information for simulation and validation of long-term climate and global change studies.

Owe, Manfred; deJeu, Vrije; VandeGriend, Adriaan A.

2000-01-01

313

Assessment of the Level-3 MODIS daily aerosol optical depth in the context of surface solar radiation and numerical weather modeling  

NASA Astrophysics Data System (ADS)

The Level-3 MODIS aerosol optical depth (AOD) product offers interesting features for surface solar radiation and numerical weather modeling applications. Remarkably, the Collection 5.1 dataset extends over more than a decade, and provides daily values of AOD over a global regular grid of 1°×1° spatial resolution. However, most of the validation efforts so far have focused on Level-2 products (10-km, at original resolution) and only rarely on Level-3 (at aggregated spatial resolution of 1°×1°). In this contribution, we compare the Level-3 Collection 5.1 MODIS AOD dataset available since 2000 against observed daily AOD values at 550 nm from more than 500 AERONET ground stations around the globe. One aim of this study is to check the advisability of this MODIS dataset for surface shortwave solar radiation calculations using numerical weather models. Overall, the mean error of the dataset is 0.03 (17%, relative to the mean ground-observed AOD), with a root mean square error of 0.14 (73%, relative to the same), albeit these values are found highly dependent on geographical region. For AOD values below about 0.3 the expected error is found very similar to that of the Level-2 product. However, for larger AOD values, higher errors are found. Consequently, we propose new functions for the expected error of the Level-3 AOD, as well as for both its mean error and its standard deviation. Additionally, we investigate the role of pixel count vis-à-vis the reliability of the AOD estimates. Our results show that a higher pixel count does not necessarily turn into a more reliable AOD estimate. Therefore, we recommend to verify this assumption in the dataset at hand if the pixel count is meant to be used. We also explore to what extent the spatial aggregation from Level-2 to Level-3 influences the total uncertainty in the Level-3 AOD. In particular, we found that, roughly, half of the error might be attributable to Level-3 AOD sub-pixel variability. Finally, we use a~radiative transfer model to investigate how the Level-3 AOD uncertainty propagates into the calculated direct normal (DNI) and global horizontal (GHI) irradiances. Overall, results indicate that, for Level-3 AODs smaller than 0.5, the induced uncertainty in DNI due to the AOD uncertainty alone is below 15% on average, and below 5% for GHI (for a solar zenith angle of 30°. However, the uncertainty in AOD is highly spatially variable, and so is that in irradiance.

Ruiz-Arias, J. A.; Dudhia, J.; Gueymard, C. A.; Pozo-Vázquez, D.

2012-09-01

314

Progress in Space Weather Modeling and Observations Needed to Improve the Operational NAIRAS Model Aircraft Radiation Exposure Predictions  

NASA Astrophysics Data System (ADS)

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting commercial aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Thus, the NAIRAS model addresses an important national need with broad societal, public health and economic benefits. The processes responsible for the variability in the solar wind, interplanetary magnetic field, solar energetic particle spectrum, and the dynamical response of the magnetosphere to these space environment inputs, strongly influence the composition and energy distribution of the atmospheric ionizing radiation field. During the development of the NAIRAS model, new science questions were identified that must be addressed in order to obtain a more reliable and robust operational model of atmospheric radiation exposure. Addressing these science questions require improvements in both space weather modeling and observations. The focus of this talk is to present these science questions, the proposed methodologies for addressing these science questions, and the anticipated improvements to the operational predictions of atmospheric radiation exposure. The overarching goal of this work is to provide a decision support tool for the aviation industry that will enable an optimal balance to be achieved between minimizing health risks to passengers and aircrew while simultaneously minimizing costs to the airline companies.

Mertens, C. J.; Kress, B. T.; Wiltberger, M. J.; Tobiska, W.; Xu, X.

2011-12-01

315

Comparison of ECMWF operational surface meteorology and buoy observations in the Ligurian Sea  

Microsoft Academic Search

Since numerical weather prediction (NWP) models are usually used to force circulation models over the ocean it is important to investigate their skill in reproducing surface meteorological parameters in open sea conditions. Near-surface meteorological data (air temperature, relative humidity, barometric pressure, wind speed and direction) have been acquired from several sensors installed onboard an offshore large spar buoy in the

R. Bozzano; A. Siccardi; M. E. Schiano; M. Borghini; S. Castellari

2003-01-01

316

Comparison of ECMWF surface meteorology and buoy observations in the Ligurian Sea  

Microsoft Academic Search

. Since numerical weather prediction (NWP) models are usually used to force ocean circulation models, it is important to investigate their skill in reproducing surface meteorological parameters in open sea conditions. Near-surface meteorological data (air temperature, relative humidity, barometric pressure, wind speed and direction) have been acquired from several sensors deployed on an offshore large spar buoy in the Ligurian

R. Bozzano; A. Siccardi; M. E. Schiano; M. Borghini; S. Castellari

2004-01-01

317

Technical Note: Surface water velocity observations from a camera: a case study on the Tiber River  

NASA Astrophysics Data System (ADS)

Monitoring surface water velocity during flood events is a challenging task. Techniques based on deploying instruments in the flow are often unfeasible due to high velocity and abundant sediment transport. A low-cost and versatile technology that provides continuous and automatic observations is still not available. LSPIV (large scale particle imaging velocimetry) is a promising approach to tackle these issues. Such technique consists of developing surface water velocity maps analyzing video frame sequences recorded with a camera. In this technical brief, we implement a novel LSPIV experimental apparatus to observe a flood event in the Tiber river at a cross-section located in the center of Rome, Italy. We illustrate results from three tests performed during the hydrograph flood peak and recession limb for different illumination and weather conditions. The obtained surface velocity maps are compared to the rating curve velocity and to benchmark velocity values. Experimental findings confirm the potential of the proposed LSPIV implementation in aiding research in natural flow monitoring.

Tauro, F.; Olivieri, G.; Petroselli, A.; Porfiri, M.; Grimaldi, S.

2014-10-01

318

World weather program  

NASA Technical Reports Server (NTRS)

A brief description of the Global Weather Experiment is presented. The world weather watch program plan is described and includes a global observing system, a global data processing system, a global telecommunication system, and a voluntary cooperation program. A summary of Federal Agency plans and programs to meet the challenges of international meteorology for the two year period, FY 1980-1981, is presented.

1980-01-01

319

The Home Weather Station.  

ERIC Educational Resources Information Center

Described is how an amateur weather observer measures and records temperature and precipitation at a well-equipped, backyard weather station. Directions for building an instrument shelter and a description of the instruments needed for measuring temperature and precipitation are included. (KR)

Steinke, Steven D.

1991-01-01

320

Complete Genome Sequence of Dyella jiangningensis Strain SBZ3-12, Isolated from the Surfaces of Weathered Rock  

PubMed Central

Dyella jiangningensis strain SBZ3-12 can weather biotite and release Al and Fe from biotite under nutrient-poor conditions. Here, we report the first complete genome sequence of D. jiangningensis strain SBZ3-12, which may facilitate a better understanding of the molecular mechanism behind mineral weathering. PMID:24831147

Bao, Yuanyuan; Kwok, Amy Ho Yan; Jiang, Jingwei; Huang, Zhi; Leung, Frederick Chi-ching; Sheng, Xiafang

2014-01-01

321

Assessment and ground-based correction of the Level-3 MODIS daily aerosol optical depth: Implications in the context of surface solar radiation prediction and numerical weather modeling  

NASA Astrophysics Data System (ADS)

The Level-3 MODIS (L3M) aerosol optical depth (AOD) product offers interesting features for surface solar radiation and numerical weather modeling applications. However, most of the validation efforts so far have been focused on Level-2 (L2M) products and only rarely on L3M. We compare the Collection 5.1 L3M AOD (Terra dataset) available since 2000 against observed daily AOD values at 550 nm from more than 500 AERONET ground stations. The aim is to check the advisability of this dataset for surface solar radiation calculations using numerical weather models. Overall, the mean error (ME) is 0.03 (17%, relative to the mean observed AOD), with a root mean square error (RMSE) of 0.14 (73%), albeit these values are found highly dependent on geographical region. For AOD values above about 0.3 the expected error (EE) is found higher than that of the L2M product. We propose specific parameterizations for the EE of the L3M AOD, as well as for both its ME and its standard deviation. We also found that, roughly, half of the uncertainty of the L3M AOD dataset might be attributable to its sub-pixel variability. Finally, we used a radiative transfer model to investigate how the L3M AOD uncertainty propagates into the direct normal (DNI) and global horizontal (GHI) irradiances evaluation. Overall, for AODs smaller than 0.5, the induced uncertainty in DNI due to AOD alone is below 15% on average, and below 5% for GHI (for a solar zenith angle of 30 degrees). But the uncertainty in AOD is highly spatially variable, so is that in irradiance. These results suggest the necessity of a correction method to reduce the bias of the L3M AOD. Ground-based AOD measurements can be also used in a data fusion procedure. We present the results of a preliminary study using optimal interpolation of L3M daily AOD data based on daily AERONET AOD measurements in the US in the period since June to August 2009. The method removes the data gaps in the original dataset, assesses the spatial distribution of uncertainty and corrects the resultant gridded-AOD based on point-wise ground measurements. Overall, based on a cross-validation procedure, the method was able to reduce the ME from 0.013 (9%) to -0.002 (-2%), the RMSE from 0.084 (59%) to 0.070 (49%) and increase the correlation coefficient from 10% to 92%. Fig 1 shows the time series of the mean daily AOD for the original (blue) and the data-fused (red) datasets over the study region. The methodology shall allow creating an accurate and long-term gridded-AOD database suitable to be ingested in numerical weather models so that the effect in the atmospheric system of AOD and its daily variability can be better assessed. Such a dataset is crucial for DNI calculations at surface.

Ruiz-Arias, J. A.; Dudhia, J.; Pozo-Vazquez, D.

2012-12-01

322

Weather Scope : An Investigative Study of Weather and Climate  

NSDL National Science Digital Library

During the course of this project, students will learn how to build instruments to measure weather, access online weather observations, collect weather data for an extended period, analyze weather data to reveal trends, and make predictions. They will develop a basic understanding of how weather can be described in measurable quantities such as temperature, wind and precipitation. The module contains five lessons relating to weather, five relating to climate, and three enrichment activities. Project information, a teacher guide, reference materials, and an ask an expert feature are also provided.

2007-12-12

323

Weather Report  

NSDL National Science Digital Library

This printable weather report is designed to help students easily note a field site's important meteorological details. The one-page PDF form asks for the following information: date, temperature, precipitation, weather type, and wind speed (based on environmental clues).

324

Weathering patterns in high latitude regolith  

NASA Astrophysics Data System (ADS)

Large areas distributed on the Earth's surface are covered by regolith, an unconsolidated heterogeneous material overlying bedrock. In high latitude areas, most of the land surface has been reworked and eroded by both glacial and fluvial processes, leaving only remnants of formerly extensive regolith covers. In an effort to further the understanding of weathering patterns and processes in old regolith covers, a comprehensive study of localities spread across Norway was carried out. Based on the distribution of minerals and elements within regolith, as well as its internal structure and geomorphologic setting, we ascertained that it was formed in situ and originated in pre-Quaternary times. There are similarities between the study sites with respect to regolith thickness, zonation, and composition. The Chemical Index of Alteration (CIA) and the Weathering Index of Parker (WIP) suggests that the degree of chemical weathering in the regolith is advanced compared to the parental bedrock with a maximum change of over 80%, which indicates a substantial increase in the proportion of secondary versus primary minerals. Mineral analysis identified kaolinite and gibbsite, which are considered indicative of advanced weathering and therefore support this observation. On the basis of statistical relationships between different grain size fractions (<125 ?m), we observed a consistent pattern, which revealed that physical weathering becomes progressively less important in the production of grains smaller than 32 ?m. Based on this finding, we infer that chemical weathering progressively dominates the production of fine silt, very fine silt, and clay, whereas physical weathering primarily controls the production of grain size fractions larger than 32 ?m. This particular pattern is suggested to be an intrinsic feature in the formation of weathered high latitude regolith.

Stromsoe, J.; Paasche, O.

2011-12-01

325

Weathering patterns in high-latitude regolith  

NASA Astrophysics Data System (ADS)

Large areas distributed on the Earth's surface are covered by regolith, an unconsolidated heterogeneous material overlying bedrock. In high-latitude areas, most of the land surface has been reworked and eroded by both glacial and fluvial processes, leaving only remnants of formerly extensive regolith covers. In an effort to further the understanding of weathering patterns and processes in old regolith covers, a comprehensive study of localities spread across Norway was carried out. On the basis of the distribution of minerals and elements within regolith, as well as its internal structure and geomorphologic setting, we ascertained that it was formed in situ and originated in pre-Quaternary times. There are similarities between the study sites with respect to regolith thickness, zonation, and composition. The Chemical Index of Alteration (CIA) and the Weathering Index of Parker (WIP) suggests that the degree of chemical weathering in the regolith is advanced compared to the parental bedrock with a maximum change of over 80%, which indicates a substantial increase in the proportion of secondary versus primary minerals. Mineral analysis identified kaolinite and gibbsite, which are considered indicative of advanced weathering and therefore support this observation. On the basis of statistical relationships between different grain size fractions (<125 ?m), we observed a consistent pattern, which revealed that physical weathering becomes progressively less important in the production of grains smaller than 32 ?m. On the basis of this finding, we infer that chemical weathering progressively dominates the production of fine silt, very fine silt, and clay, whereas physical weathering primarily controls the production of grain size fractions larger than 32 ?m. This particular pattern is suggested to be an intrinsic feature in the formation of weathered high-latitude regolith.

StrøMsøE, JøRund Raukleiv; Paasche, Øyvind

2011-09-01

326

Weather Forecasting  

NSDL National Science Digital Library

This website, supplied by Annenberg / CPB, discusses weather satellites, Doppler radar, and additional tools forecasters use to predict the weather. Students can find a wind chill calculator along with a brief discussion of the history of forecasting and weather lore. Once you have a firm grasp on the science of weather forecasting, be sure to check out the other sections of this site, which include: "ice and snow," "our changing climate," "the water cycle," and "powerful storms."

327

Emergent relation between surface vapor conductance and relative humidity profiles yields evaporation rates from weather data.  

PubMed

The ability to predict terrestrial evapotranspiration (E) is limited by the complexity of rate-limiting pathways as water moves through the soil, vegetation (roots, xylem, stomata), canopy air space, and the atmospheric boundary layer. The impossibility of specifying the numerous parameters required to model this process in full spatial detail has necessitated spatially upscaled models that depend on effective parameters such as the surface vapor conductance (C(surf)). C(surf) accounts for the biophysical and hydrological effects on diffusion through the soil and vegetation substrate. This approach, however, requires either site-specific calibration of C(surf) to measured E, or further parameterization based on metrics such as leaf area, senescence state, stomatal conductance, soil texture, soil moisture, and water table depth. Here, we show that this key, rate-limiting, parameter can be estimated from an emergent relationship between the diurnal cycle of the relative humidity profile and E. The relation is that the vertical variance of the relative humidity profile is less than would occur for increased or decreased evaporation rates, suggesting that land-atmosphere feedback processes minimize this variance. It is found to hold over a wide range of climate conditions (arid-humid) and limiting factors (soil moisture, leaf area, energy). With this relation, estimates of E and C(surf) can be obtained globally from widely available meteorological measurements, many of which have been archived since the early 1900s. In conjunction with precipitation and stream flow, long-term E estimates provide insights and empirical constraints on projected accelerations of the hydrologic cycle. PMID:23576717

Salvucci, Guido D; Gentine, Pierre

2013-04-16

328

Emergent relation between surface vapor conductance and relative humidity profiles yields evaporation rates from weather data  

PubMed Central

The ability to predict terrestrial evapotranspiration (E) is limited by the complexity of rate-limiting pathways as water moves through the soil, vegetation (roots, xylem, stomata), canopy air space, and the atmospheric boundary layer. The impossibility of specifying the numerous parameters required to model this process in full spatial detail has necessitated spatially upscaled models that depend on effective parameters such as the surface vapor conductance (Csurf). Csurf accounts for the biophysical and hydrological effects on diffusion through the soil and vegetation substrate. This approach, however, requires either site-specific calibration of Csurf to measured E, or further parameterization based on metrics such as leaf area, senescence state, stomatal conductance, soil texture, soil moisture, and water table depth. Here, we show that this key, rate-limiting, parameter can be estimated from an emergent relationship between the diurnal cycle of the relative humidity profile and E. The relation is that the vertical variance of the relative humidity profile is less than would occur for increased or decreased evaporation rates, suggesting that land–atmosphere feedback processes minimize this variance. It is found to hold over a wide range of climate conditions (arid–humid) and limiting factors (soil moisture, leaf area, energy). With this relation, estimates of E and Csurf can be obtained globally from widely available meteorological measurements, many of which have been archived since the early 1900s. In conjunction with precipitation and stream flow, long-term E estimates provide insights and empirical constraints on projected accelerations of the hydrologic cycle. PMID:23576717

Salvucci, Guido D.; Gentine, Pierre

2013-01-01

329

Coastal sea surface current observation with GOCI imagery  

NASA Astrophysics Data System (ADS)

Measurements of sea surface currents are important in understanding the dynamic of ocean processes especially in coastal waters, and satellite remote sensing has been used to derive sea surface advective velocities with visible or infrared imagery. Yet satellite remote sensing suffered from lack of high temporal imagery in dynamic coastal waters and from frequent cloud cover. In this study, using measurements from the Geo-stationary Ocean Color Imager (GOCI), we observed the sea surface currents in the East China Sea on 29 May 2011 by applying the Maximum Cross-Correlation (MCC) technique. The hourly ocean color images on 29 May 2011 (8 images per day from 8:30 am to 15:30 pm) showed water pattern movement and evolution through the course of a day, and 7 sequence sea surface velocity fields were derived. The results show that there were significant diurnal changes of the sea surface currents in the coastal waters. The average current velocity was 30~40 cm/s during the measurements, with maximum velocity of 50~60 cm/s observed between 9:30 and 10:30 am. The short-term changes of the surface velocities are mainly a result of the horizontal dilution due to tides. The case study here demonstrates the unique value of a geostationary satellite ocean color sensor in revealing short-term dynamics in coastal waters.

Lou, Xiulin; Shi, Aiqin; Zhang, Huaguo

2013-10-01

330

Surface heat budget at the Nordic Seas in Lagrangian observations  

NASA Astrophysics Data System (ADS)

In the Nordic Seas, the warm, inflowing Atlantic Water is cooled until it is dense enough to sink. Thereafter it circulates at depth, eventually feeding the North Atlantic Deep Water. The air-sea interaction which facilitates this cooling is a complex process involving diverse phenomena, from surface heating to turbulent entrainment at the base of the ocean surface mixed layer. In the present study, we use 486 freely-drifting surface buoys to observe temperature changes on water parcels and the response to air-sea heat fluxes. Such Lagrangian observations advantageously 'filter out' horizontal heat fluxes, since the buoys are advected by the flow, allowing one to focus on the vertical exchanges. We examine the temporal evolution of temperature on the drifters and the correlations with surface heat fluxes, obtained from ECMWF ERA-Interim reanalyses. The frequency spectra indicate a clear ?-2 dependence at frequencies higher than roughly 1/40 days-1. The temperature fluctuations on the other hand are correlated with surface fluxes only at the longer time scales. We then show how the Lagrangian temperature can be represented as a stochastic process, with a deterministic portion determined by the low frequency atmospheric forcing and a white noise perturbation. This is in line with previous studies of the ocean surface response to stochastic wind forcing. What distinguishes the present model is the deterministic part, which must account for the gradual cooling of the water parcels.

de La Lama, Marta S.; Isachsen, Pål E.; Koszalka, Inga; Lacasce, Joseph H.

2014-05-01

331

SOLAR AND METEOROLOGICAL SURFACE OBSERVATION NETWORK (SAMSON) FOR NC, VA  

EPA Science Inventory

Solar and Meteorological Surface Observational Network (SAMSON) v1.0 data for 6 NWS stations in North Carolina and 4 in Virginia. Hourly solar elements are: extraterrestrial horizontal and extraterrestrial direct normal radiation; global, diffuse, and direct normal radiation. Met...

332

Evaluation of beryllium surface defects observed following chemical milling  

Microsoft Academic Search

Several types of surface defects have been observed at Rockwell International's Rocky Flats Plant on beryllium parts following chemical milling. Metallography, scanning electron microscopy (SEM), and wave length dispersive spectroscopy (WDS) were used to characterize the defects. The defects were generally associated with microchemical segregation of impurities, or the chemical milling process itself. Tensile tests showed no degradation of properties

S. P. Abeln; C. L. Ferrera

1982-01-01

333

Marine surface temperature: Observed variations and data requirements  

Microsoft Academic Search

Measurements of temperature at the ocean surface are an indispensible part of the Global Climate Observing System (GCOS). We describe the varying coverage of these measurements from the mid-nineteenth century through to the present era of satellite data, along with ongoing attempts to augment the available digitized data base. We next survey attempts to remove systematic biases from both sea

D. E. Parker; C. K. Folland; M. Jackson

1995-01-01

334

Comparison of laboratory testing protocols to field observations of the weathering of sulfide-bearing mine tailings  

Microsoft Academic Search

A laboratory weathering study using a humidity cell procedure was conducted on two sulfide-bearing tailing samples from a metallurgical site in Ontario (Canada). The test was accompanied by microbiological studies to enumerate the major groups of sulfur-oxidizing bacteria and determine their potential role at different stages during the oxidation process. To evaluate the utility of this method, results were compared

Carla Ardau; David W. Blowes; Carol J. Ptacek

2009-01-01

335

Using Forecast and Observed Weather Data to Assess Performance of Forecast Products in Identifying Heat Waves and Estimating Heat Wave Effects on Mortality  

PubMed Central

Background: Heat wave and health warning systems are activated based on forecasts of health-threatening hot weather. Objective: We estimated heat–mortality associations based on forecast and observed weather data in Detroit, Michigan, and compared the accuracy of forecast products for predicting heat waves. Methods: We derived and compared apparent temperature (AT) and heat wave days (with heat waves defined as ? 2 days of daily mean AT ? 95th percentile of warm-season average) from weather observations and six different forecast products. We used Poisson regression with and without adjustment for ozone and/or PM10 (particulate matter with aerodynamic diameter ? 10 ?m) to estimate and compare associations of daily all-cause mortality with observed and predicted AT and heat wave days. Results: The 1-day-ahead forecast of a local operational product, Revised Digital Forecast, had about half the number of false positives compared with all other forecasts. On average, controlling for heat waves, days with observed AT = 25.3°C were associated with 3.5% higher mortality (95% CI: –1.6, 8.8%) than days with AT = 8.5°C. Observed heat wave days were associated with 6.2% higher mortality (95% CI: –0.4, 13.2%) than non–heat wave days. The accuracy of predictions varied, but associations between mortality and forecast heat generally tended to overestimate heat effects, whereas associations with forecast heat waves tended to underestimate heat wave effects, relative to associations based on observed weather metrics. Conclusions: Our findings suggest that incorporating knowledge of local conditions may improve the accuracy of predictions used to activate heat wave and health warning systems. Citation: Zhang K, Chen YH, Schwartz JD, Rood RB, O’Neill MS. 2014. Using forecast and observed weather data to assess performance of forecast products in identifying heat waves and estimating heat wave effects on mortality. Environ Health Perspect 122:912–918;?http://dx.doi.org/10.1289/ehp.1306858 PMID:24833618

Chen, Yeh-Hsin; Schwartz, Joel D.; Rood, Richard B.; O’Neill, Marie S.

2014-01-01

336

An attempt to comprehend Martian weathering conditions through the analysis of terrestrial palagonite samples  

NASA Technical Reports Server (NTRS)

Spectroscopic observations of the Martian surface in the invisible to near infrared (0.4-1.0 micron), coupled with measurements made by Viking, have shown that the surface is composed of a mixture of fine-grained weathered and nonweathered minerals. The majority of the weathered components are thought to be materials like smectite clays, scapolite, or palagonite. Until materials are returned for analysis there are two possible ways of proceeding with an investigation of Martian surface processes: (1) the study of weathering products in meteorites that have a Martian origin (SNC's), and (2) the analysis of certain terrestrial weathering products as analogs to the material found in SNC's, or predicted to be present on the Martian surface. We describe some preliminary measurements of the carbon chemistry of terrestrial palagonite samples that exhibit spectroscopic similarities with the Martian surface. The data should aid the understanding of weathering in SNC's and comparisons between terrestrial palagonites and the Martian surface.

Douglas, C.; Wright, I. P.; Bell, J. B.; Morris, R. V.; Golden, D. C.; Pillinger, C. T.

1993-01-01

337

World Weather  

NSDL National Science Digital Library

What's going on in the world of weather? Are there storms around Sri Lanka? What about the snows of Kilimanjaro? These can be pressing questions, indeed, and the World Weather app is a great way to stay in touch with weather patterns around the globe. Users will find that they can just type in a city name to see the current weather and also zoom around the globe as they see fit. It's a remarkable addition to the world of existing weather tracking apps and is compatible with all operating systems.

Elias, Jaume Sanchez

2014-02-20

338

On comparison of modeled surface flux variations to aircraft observations.  

SciTech Connect

Evaluation of models of air-surface exchange is facilitated by an accurate match of areas simulated with those seen by micrometeorological flux measurements. Here, spatial variations in fluxes estimated with the parameterized subgrid-scale surface (PASS) flux model were compared to flux variations seen aboard aircraft above the Walnut River Watershed (WRW) in Kansas. Despite interference by atmospheric eddies, the areas where the modeled sensible and latent heat fluxes were most highly correlated with the aircraft flux estimates were upwind of the flight segments. To assess whether applying a footprint function to the surface values would improve the model evaluation, a two-dimensional correlation distribution was used to identify the locations and relative importance of contributing modeled surface pixels upwind of each segment of the flight path. The agreement between modeled surface fluxes and aircraft measurements was improved when upwind fluxes were weighted with an optimized footprint parameter {var_phi}, which can be estimated from wind profiler data and surface eddy covariance. Variations of the flight-observed flux were consistently greater than those modeled at the surface, perhaps because of the smoothing effect of using 1 km pixels in the model. In addition, limited flight legs prevented sufficient filtering of the effects of atmospheric convection, possibly accounting for some of the more prominent changes in fluxes measured along the flight paths.

Song, J.; Wesely, M. L.; Environmental Research; Northern Illinois Univ.

2003-07-30

339

Improving Numerical Weather Predictions of Summertime Precipitation Over the Southeastern U.S. Through a High-Resolution Initialization of the Surface State  

NASA Technical Reports Server (NTRS)

It is hypothesized that high-resolution, accurate representations of surface properties such as soil moisture and sea surface temperature are necessary to improve simulations of summertime pulse-type convective precipitation in high resolution models. This paper presents model verification results of a case study period from June-August 2008 over the Southeastern U.S. using the Weather Research and Forecasting numerical weather prediction model. Experimental simulations initialized with high-resolution land surface fields from the NASA Land Information System (LIS) and sea surface temperature (SST) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) are compared to a set of control simulations initialized with interpolated fields from the National Centers for Environmental Prediction 12-km North American Mesoscale model. The LIS land surface and MODIS SSTs provide a more detailed surface initialization at a resolution comparable to the 4-km model grid spacing. Soil moisture from the LIS spin-up run is shown to respond better to the extreme rainfall of Tropical Storm Fay in August 2008 over the Florida peninsula. The LIS has slightly lower errors and higher anomaly correlations in the top soil layer, but exhibits a stronger dry bias in the root zone. The model sensitivity to the alternative surface initial conditions is examined for a sample case, showing that the LIS/MODIS data substantially impact surface and boundary layer properties.

Case, Jonathan L.; Kumar, Sujay V.; Krikishen, Jayanthi; Jedlovec, Gary J.

2011-01-01

340

On surface temperature, greenhouse gases, and aerosols: models and observations  

SciTech Connect

The effect of changes in atmospheric carbon dioxide concentrations and sulphate aerosols on near-surface temperature is investigated using a version of the Hadley Centre atmospheric model coupled to a mixed layer ocean. The scattering of sunlight by sulphate aerosols is represented by appropriately enhancing the surface albedo. On doubling atmospheric carbon dioxide concentrations, the global mean temperature increases by 5.2 K. An integration with a 39% increase in CO{sub 2}, giving the estimated change in radiative heating due to increases in greenhouse gases since 1900, produced an equilibrium warming of 2.3 K, which, even allowing for oceanic inertia, is significantly higher than the observed warming over the same period. Furthermore, the simulation suggests a substantial warming everywhere, whereas the observations indicate isolated regions of cooling, including parts of the northern midlatitude continents. The addition of an estimate of the effect of scattering by current industrial aerosols (uncertain by a factor of at least 3) leads to improved agreement with the observed pattern of changes over the northern continents and reduces the global mean warming by about 30%. Doubling the aerosol forcing produces patterns that are still compatible with the observations, but further increase leads to unrealistically extensive cooling in the midlatitudes. The diurnal range of surface temperature decreases over most of the northern extratropics on increasing CO{sub 2}, in agreement with recent observations. The addition of the current industrial aerosol had little detectable effect on the diurnal range in the model because the direct effect of reduced solar heating at the surface is approximately balanced by the indirect effects of cooling. Thus, the ratio of the reduction in diurnal range to the mean warming is increased, in closer agreement with observations. Results from further sensitivity experiments with larger increases in aerosol and CO{sub 2} are presented.

Mitchell, J.F.B.; Davis, R.A.; Ingram, W.J.; Senior, C.A. [Hadley Centre for Climate Prediction and Research, Berkshire (United Kingdom)] [Hadley Centre for Climate Prediction and Research, Berkshire (United Kingdom)

1995-10-01

341

Global chemical weathering and associated P-release  

NASA Astrophysics Data System (ADS)

Chemical weathering releases phosphorus to soils and ecosystems. To improve understanding of the spatial distribution of the global P-release characteristics, a model framework for estimating global chemical weathering rates was coupled with geochemical information. Results suggest that the global soil shielding reduces chemical weathering fluxes by about 44%, compared to an Earth surface with no deeply weathered soils but relatively young rock surfaces (e.g. as in volcanic arc and other tectonically active areas). About 70% of the weathering fluxes globally derive from 10% of the land area, with Southeast Asia being a primary "hot spot" of chemical weathering and for P-release. In contrast, only 50% of runoff is attributed to 10% of the land area; thus the global chemical weathering rating curve is to some extent disconnected from the global runoff curve due to the spatially heterogeneous climate as well as differences in rock and soil properties. In addition to total chemical weathering fluxes, the release of P, a nutrient that controls biological productivity at large spatial scales, is affected by the spatial correlation between runoff, lithology, temperature and soil properties. The areal abundance of deeply weathered soils in Earth's past may have influenced weathering fluxes and P-fuelled biological productivity significantly, specifically in the case of larger climate shifts when high runoff fields shift to areas with thinner soils or areas with more weatherable rocks and relatively increased P-content. This observation may be particularly important for spatially resolved Earth system models targeting geological time scales. The full research text can be found in: Hartmann, J., N. Moosdorf, R. Lauerwald, M. Hinderer, A.J. West (2014) Global chemical weathering and associated P-release - the role of lithology, temperature and soil properties. Chemical Geology 363, 145-163. doi: 10.1016/j.chemgeo.2013.10.025 (open access)

Hartmann, Jens; Moosdorf, Nils; Lauerwald, Ronny; Hinderer, Matthias; West, A. Joshua

2014-05-01

342

Global Surface Thermal Inertia Derived from Dawn VIR Observations  

NASA Astrophysics Data System (ADS)

Comparisons of surface temperatures, derived from Dawn [1] Visible and Infrared Mapping Spectrometer (VIR-MS) [2] observations , to thermal models suggest that Vesta generally has a low-thermal-inertia surface, between 25 and 35 J m^-2 K^-1 s^-½, consistent with a thick layer of fine-grain material [3]. Temperatures were calculated using a Bayesian approach to nonlinear inversion as described by Tosi et al. [4]. In order to compare observed temperatures of Vesta to model calculations, several geometric and photometric parameters must be known or estimated. These include local mean solar time, latitude, local slope, bond bolometric albedo, and the effective emissivity at 5?m. Local time, latitude, and local slope are calculated using the USGS ISIS software system [5]. We employ a multi-layered thermal-diffusion model called 'KRC' [6], which has been used extensively in the study of Martian thermophysical properties. This thermal model is easily modified for use with Vesta by replacing the Martian ephemeris input with the Vesta ephemeris and disabling the atmosphere. This model calculates surface temperatures throughout an entire Vesta year for specific sets of slope, azimuth, latitude and elevation, and a range of albedo and thermal-inertia values. The ranges of albedo and thermal inertia values create temperature indices that are closely matched to the dates and times observed by VIR. Based on observed temperatures and best-fit KRC thermal models, estimates of the annual mean surface temperatures were found to range from 176 K - 188 K for flat zenith-facing equatorial surfaces, but these temperatures can drop as low as 112 K for polar-facing slopes at mid-latitudes. [7] In this work, we will compare observed temperatures of the surface of Vesta (using data acquired by Dawn VIR-MS [2] during the approach, survey, high-altitude mapping and departure phases) to model temperature results using the KRC thermal model [5]. Where possible, temperature observations from multiple times of day or seasons will be used to better constrain the thermal inertia. The authors gratefully acknowledge the support of the Dawn Instrument, Operations, and Science Teams. This work was funded by the Dawn at Vesta Participating Science Program. [1] C.T. Russell et al. (2004) P&SS, 52, 465-489. [2] M.C. De Sanctis et al. (2011) SSRv 163, 329. [3] M.T. Capria et al. (2012) LPSC XLIII #1863 [4] F. Tosi et al. (2012) LPSC XLIII #1886. [5] J. Anderson et al. (2011) AGU Fall Meeting, #U31A-0009. [6] H.H. Kieffer H., et al. (1977) JGR, 82, 4249-4291. [7] Titus et al. (2012) EPSC, #800.

Titus, T. N.; Becker, K. J.; Anderson, J.; Capria, M.; Tosi, F.; Prettyman, T. H.; De Sanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.; McCord, T. B.; Li, J. Y.; Russell, C. T.; Raymond, C. A.

2012-12-01

343

Linking the Weather Generator with Regional Climate Model  

NASA Astrophysics Data System (ADS)

One of the downscaling approaches, which transform the raw outputs from the climate models (GCMs or RCMs) into data with more realistic structure, is based on linking the stochastic weather generator with the climate model output. The present contribution, in which the parametric daily surface weather generator (WG) M&Rfi is linked to the RCM output, follows two aims: (1) Validation of the new simulations of the present climate (1961-1990) made by the ALADIN-Climate Regional Climate Model at 25 km resolution. The WG parameters are derived from the RCM-simulated surface weather series and compared to those derived from weather series observed in 125 Czech meteorological stations. The set of WG parameters will include statistics of the surface temperature and precipitation series (including probability of wet day occurrence). (2) Presenting a methodology for linking the WG with RCM output. This methodology, which is based on merging information from observations and RCM, may be interpreted as a downscaling procedure, whose product is a gridded WG capable of producing realistic synthetic multivariate weather series for weather-ungauged locations. In this procedure, WG is calibrated with RCM-simulated multi-variate weather series in the first step, and the grid specific WG parameters are then de-biased by spatially interpolated correction factors based on comparison of WG parameters calibrated with gridded RCM weather series and spatially scarcer observations. The quality of the weather series produced by the resultant gridded WG will be assessed in terms of selected climatic characteristics (focusing on characteristics related to variability and extremes of surface temperature and precipitation). Acknowledgements: The present experiment is made within the frame of projects ALARO-Climate (project P209/11/2405 sponsored by the Czech Science Foundation), WG4VALUE (project LD12029 sponsored by the Ministry of Education, Youth and Sports of CR) and VALUE (COST ES 1102 action).

Dubrovsky, Martin; Farda, Ales; Skalak, Petr; Huth, Radan

2013-04-01

344

Observing the surface of Venus with VIRTIS on Venus Express  

NASA Astrophysics Data System (ADS)

The M channel of VIRTIS will allow the first systematic mapping of the surface and of the near-surface atmosphere of Venus in the near infrared wavelengths range This will be done using the atmospheric windows located at 1 10 1 18 mu m and if possible additionally using the window at 1 02 mu m Wattson and Rothman 1986 Kamp et al 1988 Moroz 2002 The latter is unfortunately right at the low end of the wavelength range of the IR channel and at the upper end of the VIS channel Therefore the usability of this window is unclear until first data from Venus are obtained The atmospheric windows will allow measuring the thermal emission of the surface as was demonstrated by Galileo NIMS Carlson et al 1991 and Cassini VIMS Baines et al 2000 While the atmospheric windows show no or little CO 2 absorption the radiance from the surface is still affected by scattering in the clouds This effect varies based on the optical thickness of the clouds We have developed a quicklook processing procedure which allows deriving surface emissivity variations from nighttime observations correcting for the atmospheric effects We will present the first version of this algorithm During the mission the algorithm will be refined based on the data returned from the different instruments on Venus Express The final goal is to derive maps of the absolute surface emissivity Based on these data two main science tasks for the surface analysis will be pursued Classification of the surface composition and study the interaction between low atmosphere and

Helbert, J.; Mariangeli, L.; Baines, K. H.; Garcia, R.; Erard, S.; Piccioni, G.; Drossart, P.; Müller, N.; Hashimoto, G.; Kostama, P.; Virtis Team

345

High-frequency radar observations of ocean surface currents.  

PubMed

This article reviews the discovery, development, and use of high-frequency (HF) radio wave backscatter in oceanography. HF radars, as the instruments are commonly called, remotely measure ocean surface currents by exploiting a Bragg resonant backscatter phenomenon. Electromagnetic waves in the HF band (3-30 MHz) have wavelengths that are commensurate with wind-driven gravity waves on the ocean surface; the ocean waves whose wavelengths are exactly half as long as those of the broadcast radio waves are responsible for the resonant backscatter. Networks of HF radar systems are capable of mapping surface currents hourly out to ranges approaching 200 km with a horizontal resolution of a few kilometers. Such information has many uses, including search and rescue support and oil-spill mitigation in real time and larval population connectivity assessment when viewed over many years. Today, HF radar networks form the backbone of many ocean observing systems, and the data are assimilated into ocean circulation models. PMID:22809196

Paduan, Jeffrey D; Washburn, Libe

2013-01-01

346

Titan's Surface Temperatures Maps from Cassini - CIRS Observations  

NASA Astrophysics Data System (ADS)

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 ?m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature profile by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). In future, application of our methodology over wide areas should greatly increase the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L105, 2009.

Cottini, Valeria; Nixon, C. A.; Jennings, D. E.; Anderson, C. M.; Samuelson, R. E.; Irwin, P. G. J.; Flasar, F. M.

2009-09-01

347

ATLAS-3 correlative measurement opportunities with UARS and surface observations  

NASA Technical Reports Server (NTRS)

The third ATmospheric Laboratory for Applications and Science (ATLAS-3) mission was flown aboard the Space Shuttle launched on November 3, 1994. The mission length was approximately 10 days and 22 hours. The ATLAS-3 Earth-viewing instruments provided a large number of measurements which were nearly coincident with observations from experiments on the Upper Atmosphere Research Satellite (UARS). Based on ATLAS-3 instrument operating schedules, simulations were performed to determine when and where correlative measurements occurred between ATLAS and UARS instruments, and between ATLAS and surface observations. Results of these orbital and instrument simulations provide valuable information for scientists to compare measurements between various instruments on the two satellites and at selected surface sites.

Harrison, Edwin F.; Denn, Fred M.; Gibson, Gary G.

1995-01-01

348

Rates of Chemical Weathering  

NSDL National Science Digital Library

In this activity, students will investigate the weathering of rocks by chemical processes. They will use effervescent cleansing tablets as a model for rock, and vary surface area, temperature, and acidity to see how rapidly the "rock" dissolves. This investigation will help them understand three of the factors that affect the rate of chemical weathering and develop better understanding of how to design controlled experiments by exploring only one experimental variable at a time.

Michael Passow

349

Observation of surface dark solitons in nonlocal nonlinear media.  

PubMed

We investigated surface dark solitons (SDSs) at the interface between a self-defocusing nonlocal nonlinear medium and a linear medium, both theoretically and experimentally. We demonstrate that fundamental and higher-order SDSs can exist when the linear refractive index of the self-defocusing medium is much greater than that of the linear medium. The fundamental and second-order solitons are observed at the interface between air and a weakly absorbing liquid. PMID:24978730

Gao, XingHui; Wang, Jing; Zhou, Luohong; Yang, ZhenJun; Ma, Xuekai; Lu, Daquan; Guo, Qi; Hu, Wei

2014-07-01

350

The Impact of Ensemble Kalman Filter Assimilation of Near-Surface Observations on the Predictability of Atmospheric Conditions over Complex Terrain: Results from Recent MATERHORN Field Program  

NASA Astrophysics Data System (ADS)

Near-surface atmospheric observations are the main conventional observations for weather forecasts. However, in modern numerical weather prediction, the use of surface observations, especially those data over complex terrain, remains a unique challenge. There are fundamental difficulties in assimilating surface observations with three-dimensional variational data assimilation (3DVAR). In our early study[1] (Pu et al. 2013), a series of observing system simulation experiments was performed with the ensemble Kalman filter (EnKF) and compared with 3DVAR for its ability to assimilate surface observations with 3DVAR. Using the advanced research version of the Weather Research and Forecasting (WRF) model, results demonstrate that the EnKF can overcome some fundamental limitations that 3DVAR has in assimilating surface observations over complex terrain. Specifically, through its flow-dependent background error term, the EnKF produces more realistic analysis increments over complex terrain in general. Over complex terrain, the EnKF clearly performs better than 3DVAR, because it is more capable of handling surface data in the presence of terrain misrepresentation. With this presentation, we further examine the impact of EnKF data assimilation on the predictability of atmospheric conditions over complex terrain with the WRF model and the observations obtained from the most recent field experiments of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program. The MATERHORN program provides comprehensive observations over mountainous regions, allowing the opportunity to study the predictability of atmospheric conditions over complex terrain in great details. Specifically, during fall 2012 and spring 2013, comprehensive observations were collected of soil states, surface energy budgets, near-surface atmospheric conditions, and profiling measurements from multiple platforms (e.g., balloon, lidar, radiosondes, etc.) over Dugway Proving Ground (DPG), Utah. With the near-surface observations and sounding data obtained during the MATERHORN fall 2012 field experiment, a month-long cycled EnKF analysis and forecast was produced with the WRF model and an advanced EnKF data assimilation system. Results are compared with the WRF near real-time forecasting during the same month and a set of analysis with 3DVAR data assimilation. Overall evaluation suggests some useful insights on the impacts of different data assimilation methods, surface and soil states, terrain representation on the predictability of atmospheric conditions over mountainous terrain. Details will be presented. References [1] Pu, Z., H. Zhang, and J. A. Anderson,. 'Ensemble Kalman filter assimilation of near-surface observations over complex terrain: Comparison with 3DVAR for short-range forecasts.' Tellus A, vol. 65,19620. 2013. http://dx.doi.org/10.3402/tellusa.v65i0. 19620.

Pu, Z.; Zhang, H.

2013-12-01

351

Where fast weathering creates thin regolith and slow weathering creates thick regolith  

SciTech Connect

Weathering disaggregates rock into regolith the fractured or granular earthmaterial that sustains life on the continental land surface. Here, we investigate what controls the depth of regolith formed on ridges of two rock compositions with similar initial porosities in Virginia (USA).A priori, we predicted that the regolith on diabasewould be thicker than on granite because the dominant mineral (feldspar) in the diabase weathers faster than its granitic counterpart. However, weathering advanced 20deeper into the granite than the diabase. The 20-thicker regolith is attributed mainly to connected micron-sized pores, microfractures formed around oxidizing biotite at 20m depth, and the lower iron (Fe) content in the felsic rock. Such porosity allows pervasive advection and deep oxidation in the granite. These observations may explainwhy regolithworldwide is thicker on felsic compared tomafic rock under similar conditions. To understand regolith formationwill require better understanding of such deep oxidation reactions and how they impact fluid flow during weathering.

Bazilevskaya, Ekaterina [Pennsylvania State University, University Park, PA; Lebedeva, Marina [Pennsylvania State University, University Park, PA; Pavich, Milan [U.S. Geological Survey, Reston, VA; Rother, Gernot [ORNL; Parkinson, D. Y. [Advanced Light Source, LBNL; Cole, David [Ohio State University; Brantley, S. L. [Pennsylvania State University, University Park, PA

2012-01-01

352

Chemical Weathering  

NSDL National Science Digital Library

This tombstone weathering lab is designed to provide students with tangible understanding of chemical weathering and weathering rates. To prepare for this lab, students will have learned in previous labs to identify common minerals and rocks and will have attended lectures about the process of chemical weathering. During the first part of the lab we travel to the city cemetery to collect data on the age and extent of chemical weathering of tombstones that are made of limestone and igneous rocks. After collecting data for ~1 hour, we return to the computer lab where students use Microsoft Excel to analyze and interpret their data. Their task is to calculate a chemical weathering rate for limestone for our region and compare that rate to those from other regions. This activity gives students experience in the process of scientific inquiry: data collection, data analysis and data interpretation. Students develop Microsoft Excel skills: writing formulas, producing charts, understanding trendlines and R2 values.

Kira Lawrence

353

Hyperspectral Observations of Land Surfaces Using Ground-based, Airborne, and Satellite Sensors  

NASA Astrophysics Data System (ADS)

The University of Wisconsin-Madison Space Science and Engineering Center (UW-SSEC) has helped pioneer the use of high spectral resolution infrared spectrometers for application to atmospheric and surface remote sensing. This paper is focused on observations of land surface infrared emission from high spectral resolution measurements collected over the past 15 years using airborne, ground-based, and satellite platforms. The earliest data was collected by the High-resolution Interferometer Sounder (HIS), an instrument designed in the 1980s for operation on the NASA ER-2 high altitude aircraft. The HIS was replaced in the late 1990s by the Scanning-HIS instrument which has flown on the NASA ER-2, WB-57, DC-8, and Scaled Composites Proteus aircraft and continues to support field campaigns, such as those for EOS Terra, Aqua, and Aura validation. Since 1995 the UW-SSEC has fielded a ground-based Atmospheric Emitted Radiance Interferometer (AERI) in a research vehicle (the AERIBAGO) which has allowed for direct field measurements of land surface emission from a height of about 16 ft above the ground. Several ground-based and aircraft campaigns were conducted to survey the region surrounding the ARM Southern Great Plains site in north central Oklahoma. The ground- based AERIBAGO has also participated in surface emissivity campaigns in the Western U.S.. Since 2002, the NASA Atmospheric InfraRed Sounder (AIRS) has provided similar measurements from the Aqua platform in an afternoon sun-synchronous polar orbit. Ground-based and airborne observations are being used to validate the land surface products derived from the AIRS observations. These cal/val activities are in preparation for similar measurements anticipated from the operational Cross-track InfraRed Sounder (CrIS) on the NPOESS Preparatory Platform (NPP), expected to be launched in 2008. Moreover, high spectral infrared observations will soon be made by the Infrared Atmospheric Sounder Interferometer (IASI) on the European MetOp platform as well as a planned series of Chinese polar orbiting satellites. The detailed understanding of the land surface infrared emission is a crucial step in the effective utilization of these advanced sounder instruments for the extraction of atmospheric composition information (esp. water vapor vertical profile) over land, which is a key goal for numerical weather prediction data assimilation.

Knuteson, R. O.; Best, F. A.; Revercomb, H. E.; Tobin, D. C.

2006-12-01

354

Weather Data  

NSDL National Science Digital Library

The listed websites are recommended safe kid friendly sites that may be used when gathering data for the at home data project. Use the websites listed to learn more about daily weather patterns in different cities around the world. After you have collected and organized your data, create a graph representing the different weather patterns in that city. Use this site to record the daily high temperature for your assigned city. The Weather Channel Use this ...

Ms. Harris

2011-01-24

355

Predicting Weather  

NSDL National Science Digital Library

By performing the activities presented in this website, fourth grade students can learn about weather instruments and data collection. This website, produced by the Government of Saskatchewan, also explores how the weather can impact local communities. Each activity presented here includes both objectives and assessment techniques for the lesson. Sixteen different activity suggestions provide students and teachers with ample opportunities to explore weather in the classroom.

356

Weather Watch  

NSDL National Science Digital Library

The weather watch activity is designed to provide instruction on how to collect weather data from on-line databases. Following completion of this activity the user will be able to look up weather conditions for any city in North America, know what radar maps are used for and how to access them, and know how to access satellite images and make estimated guesses on cloud conditions for their area from them.

R. Hopson

357

Weather Experiments  

NSDL National Science Digital Library

Looking for fun ways to learn about weather? Weather Wiz Kids has 39 fun weather related experiments for you to try. These experiments can be done in the classroom with your friends or even at home! Some of the experiments on the site include: tornado in a bottle, make lightning, make it rain, cloud in a bottle, what's in the wind, the Doppler Effect, and baking soda volcano.

2010-01-01

358

Observation of dynamic water microadsorption on Au surface  

SciTech Connect

Experimental and theoretical research on water wettability, adsorption, and condensation on solid surfaces has been ongoing for many decades because of the availability of new materials, new detection and measurement techniques, novel applications, and different scales of dimensions. Au is a metal of special interest because it is chemically inert, has a high surface energy, is highly conductive, and has a relatively high melting point. It has wide applications in semiconductor integrated circuitry, microelectromechanical systems, microfluidics, biochips, jewelry, coinage, and even dental restoration. Therefore, its surface condition, wettability, wear resistance, lubrication, and friction attract a lot of attention from both scientists and engineers. In this paper, the authors experimentally investigated Au{sub 2}O{sub 3} growth, wettability, roughness, and adsorption utilizing atomic force microscopy, scanning electron microscopy, reflectance spectrometry, and contact angle measurement. Samples were made using a GaAs substrate. Utilizing a super-hydrophilic Au surface and the proper surface conditions of the surrounding GaAs, dynamic microadsorption of water on the Au surface was observed in a clean room environment. The Au surface area can be as small as 12??m{sup 2}. The adsorbed water was collected by the GaAs groove structure and then redistributed around the structure. A model was developed to qualitatively describe the dynamic microadsorption process. The effective adsorption rate was estimated by modeling and experimental data. Devices for moisture collection and a liquid channel can be made by properly arranging the wettabilities or contact angles of different materials. These novel devices will be very useful in microfluid applications or biochips.

Huang, Xiaokang, E-mail: xiaokang.huang@tqs.com; Gupta, Gaurav; Gao, Weixiang; Tran, Van; Nguyen, Bang; McCormick, Eric; Cui, Yongjie; Yang, Yinbao; Hall, Craig; Isom, Harold [TriQuint Semiconductor, Inc., 500 W Renner Road, Richardson, Texas 75080 (United States)

2014-05-15

359

Assimilation of Smos Observations to Generate a Prototype SMAP Level 4 Surface and Root-Zone Soil Moisture Product  

NASA Technical Reports Server (NTRS)

The Soil Moisture Active and Passive (SMAP; [1]) mission is being implemented by NASA for launch in October 2014. The primary science objectives of SMAP are to enhance understanding of land surface controls on the water, energy and carbon cycles, and to determine their linkages. Moreover, the high-resolution soil moisture mapping provided by SMAP has practical applications in weather and seasonal climate prediction, agriculture, human health, drought and flood decision support. The Soil Moisture and Ocean Salinity (SMOS; [2]) mission was launched by ESA in November 2009 and has since been observing L-band (1.4 GHz) upwelling passive microwaves. In this paper we describe our use of SMOS brightness temperature observations to generate a prototype of the planned SMAP Level 4 Surface and Root-zone Soil Moisture (L4_SM) product [5].

Reichle, Rolf H.; De Lannoy, Gabrielle J. M.; Crow, Wade T.; Koster, Randal D.; Kimball, John

2012-01-01

360

Sensitivity of surface meteorological analyses to observation networks  

NASA Astrophysics Data System (ADS)

A computationally efficient variational analysis system for two-dimensional meteorological fields is developed and described. This analysis approach is most efficient when the number of analysis grid points is much larger than the number of available observations, such as for large domain mesoscale analyses. The analysis system is developed using MATLAB software and can take advantage of multiple processors or processor cores. A version of the analysis system has been exported as a platform independent application (i.e., can be run on Windows, Linux, or Macintosh OS X desktop computers without a MATLAB license) with input/output operations handled by commonly available internet software combined with data archives at the University of Utah. The impact of observation networks on the meteorological analyses is assessed by utilizing a percentile ranking of individual observation sensitivity and impact, which is computed by using the adjoint of the variational surface assimilation system. This methodology is demonstrated using a case study of the analysis from 1400 UTC 27 October 2010 over the entire contiguous United States domain. The sensitivity of this approach to the dependence of the background error covariance on observation density is examined. Observation sensitivity and impact provide insight on the influence of observations from heterogeneous observing networks as well as serve as objective metrics for quality control procedures that may help to identify stations with significant siting, reporting, or representativeness issues.

Tyndall, Daniel Paul

361

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations  

NASA Astrophysics Data System (ADS)

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L105, 2009.

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

362

Advanced Methods of Observing Surface Plasmon Polaritons and Magnons  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Requires signed TDF. The primary objectives of this thesis are the investigation of the theoretical and experimental aspects of the design and construction of advanced techniques for the excitation of surface plasmon-polaritons, surface magneto -plasmon-polaritons and surface magnons. They involve on -line observation of these phenomena and to accomplish these goals, analytical studies of the characteristic behaviour of these phenomena have been undertaken. For excitations of surface plasmon- and surface magneto-plasmon-polaritons the most robust and conventional configuration, namely Prism-Medium-Air, coupled to a novel angle scan (prism spinning) method was employed. The system to be described here can automatically measure the reflectivity of a multilayer system over a range of angles that includes the resonance angle in an Attenuated Total Reflection (ATR) experiment. The computer procedure that controls the system is quite versatile so that it allows any right-angle prism of different angle or refractive index to be utilised. It also provided probes to check for optical alignment within the system. Moreover, it performs the angular scan many times and then averages the results in order to reduce the environmental and other possible sources of noise within the system. The mechanical side of the system is unique and could eventually be adopted as a marketable piece of equipment. It consists of a turntable for holding the prism-sample assembly and a drive motor in conjunction with a servo-potentiometer whose output not only operates the turntable but also sends a signal to a computer to measure accurately its position. The interface unit enables a computer to control automatically an angular scan ATR experiment for measuring the resonance reflectivity spectrum of a multilayer system. The interface unit uses an H-bridge switch formed by four bipolar power transistor and two small signal MOSFETs to convert the digital signal from the computer into a voltage drive for the motor. Surface plasmon-polaritons can become surface magneto-plasmon-polaritons in the presence of an external magnetic field. The metal used for this purpose was a nickel film. Observation of these effects permits a measurement of certain magneto-optical coefficients that are potentially of technological importance. The mechanical side of the surface plasmon (zero field) equipment was redesigned and reconstructed for the excitation and observation of surface magneto-plasmon polaritons. The final part of the thesis is concerned with excitation of magneto-static waves (MSW) and their observation by Brillouin light scattering. Optical set up has been designed that can be used for simultaneous forward and backscattering geometries. This was then used with a multiple pass advanced Fabry-Perot interferometer together with a conventional multichannel analyser to observe MSW. (Abstract shortened by UMI.).

Moghaddam, Abolghasem Mobaraki

363

TES Observations of Chryse and Acidalia Planitiae: Multiple Working Hypotheses for Distributions of Surface Compositions  

NASA Technical Reports Server (NTRS)

A gradation of surface units represents either (1) an influx of basaltic sediment from southern highlands, deposited on andesitic volcanics, or (2) incompletely weathered basalt marking the geographic extent of submarine alteration of basaltic crust. Additional information is contained in the original extended abstract.

Wyatt, M. B.; Bandfield, J. L.; McSween, H. Y., Jr.; Christensen, P. R.; Moersch, J.

2002-01-01

364

The WegenerNet observing weather and climate at 1 km-scale resolution: a new look at convective precipitation and other local-scale processes  

NASA Astrophysics Data System (ADS)

The region Feldbach in Eastern Styria, Austria, characteristic for experiencing a rich variety of weather and climate patterns, has been selected by the WegCenter as a focus area for a pioneering weather and climate observation experiment at very high resolution: The WegenerNet climate station network region Feldbach (in brief WegenerNet) is comprised of 151 meteorological stations, which measure temperature, humidity, precipitation, and other parameters, with high accuracy in a tightly spaced grid (one station per ~2 km2; each with 5-min time sampling; ~1.4 km x 1.4 km grid in an ~20 km x 15 km area centered near the City of Feldbach at 46.93 °N, 15.90 °E). Since Jan 2007 the WegenerNet is providing, as part of the pilot and demonstration phase, regular measurements from the entire grid and since fall 2008 a complete quality-controlled data stream is available in near real time (data latency less than 1-2 hours) for visualization and download via the WegenerNet data portal (www.wegenernet.org). Currently (early 2009) the network demonstration is moving into its final phase, with consolidating maintenance procedures, advancing weather and climate data product development and completing the data portal bilingually (German, English). Full operations is foreseen to be reached mid 2009, from which on the net is scheduled as a long-term field experiment serving as a high-resolution monitoring and validation site for weather and climate research and applications. Adding further value, the WegenerNet data are complemented by lightening measurements in cooperation with the Inst. of Physics/Univ. of Munich (European LiNet network, including dedicated stations in Feldbach and Graz). In addition, a 3D-steerable Doppler weather radar (of the Styrian Hail Protection Society at Reicherhöhe near Graz) is available with un-obscured view of clouds and rain over the WegenerNet area, focusing its measurements on hail and heavy rainfall. Complementary hailpad measurements are planned as well (as of 2009). Many research projects investigating climate and environmental change and impacts, as well as local weather (extremes), will benefit from WegenerNet data covering the local scales from 1-10 km. This is a key domain for future high-resolution climate modeling and analysis, currently mainly covering the 10-50 km scale, for meeting the needs of climate impact models and studies in heterogeneous orography such as the Alpine region. Applications include validation of non-hydrostatic climate models operated at 1-10 km resolution for dynamical downscaling, validation of statistical climate downscaling techniques, in particular for precipitation, "ground-truth" provision for and validation of high-resolution atmospheric and hydrologic Earth observation data from satellites, validation of weather radar rain rate estimates, study of orography-local climate relationships, basin-scale and local water balance assessments, and many others. The presentation will introduce the WegenerNet and its characteristics and capabilities along the lines above and will show example applications of its (1 km x 1 km) weather and climate products, with focus on the highly-variable convective summer precipitation. On-line access will also be demonstrated (www.wegcenter.at/wegenernet, www.wegenernet.org).

Kirchengast, G.; Kabas, T.; Stieb, C.; Leuprecht, A.; Bichler, C.

2009-04-01

365

A systematic evaluation of the lagged effects of spatiotemporally relative surface weather types on wintertime cardiovascular-related mortality across 19 US cities  

NASA Astrophysics Data System (ADS)

Previous research using varying methods has shown that the day-to-day variability in cardiovascular (CV)-related mortality is correlated with a number of different meteorological variables, though these relationships can vary geographically. This research systematically examines the relationship between anomalous winter CV-related mortality and geographically and seasonally relative multivariate surface weather types derived from a recently developed gridded weather typing classification (GWTC) for cities in varying climate regions of the United States of America (USA). Results indicate that for all locations examined, during winter, a dry and cool (DC) weather type is significantly related to increased CV-related mortality, especially in the 2 weeks immediately after it occurs, with no apparent mortality displacement. Across the USA as a whole, the peak of this relationship is a 4.1% increase in CV-related mortality at a lag of 3 days. Spike days in CV-related mortality show similar trends, being over 50% more likely 2 to 4 days after the DC type occurs. A humid and warm (HW) weather type exhibited a significant and opposite relationship to that of DC. While these results for DC and HW were statistically significant at every location examined, the magnitudes were larger in the warmer locations. Among other weather types, Warm Front Passages (WFP) were also related to significant increases in CV-related mortality, especially 1 day after they occurred. Though this link was much more varied geographically than results found with DC or HW, it suggests that sequences of multiple DC days followed by WFP may result in increased CV-related mortality.

Lee, Cameron C.

2015-02-01

366

Utilization of satellite imagery by in-flight aircraft. [for weather information  

NASA Technical Reports Server (NTRS)

Present and future utilization of satellite weather data by commercial aircraft while in flight was assessed. Weather information of interest to aviation that is available or will become available with future geostationary satellites includes the following: severe weather areas, jet stream location, weather observation at destination airport, fog areas, and vertical temperature profiles. Utilization of this information by in-flight aircraft is especially beneficial for flights over the oceans or over remote land areas where surface-based observations and communications are sparse and inadequate.

Luers, J. K.

1976-01-01

367

Assimilating Soil Moisture Using Surface Observations Coupled with a Land Surface Model  

NASA Astrophysics Data System (ADS)

To improve the accuracy of atmospheric boundary layer simulation, we propose and have validated an inverse technique for assimilating soil moisture using surface observations. We followed a thermodynamical approach to perform a continuous data assimilation of surface-layer temperature and water vapor mixing ratio to develop dynamically consistent surface-atmosphere coupling. First, we used the analyzed surface data to directly assimilate surface-layer temperature and water vapor mixing ratio. We then used the difference between the observations and model predictions to calculate adjustments to the surface fluxes of sensible and latent heat. These adjustments were used to calculate a new estimate of the ground temperature, thereby affecting the predicted surface fluxes in the subsequent time step. We also used the adjusted latent heat fluxes to calculate changes in soil moisture using an inverse method. This indirect data assimilation of ground temperature and soil moisture was applied simultaneously with the direct assimilation of surface data in the model's surface layer, thereby maintaining greater consistency between the surface layer mass-field variables and the ground temperature and moisture. This technique was tested for two different land surface models: a diagnostic scheme based on land use and prespecified soil moisture availability, Ma, following Carlson and Boland as used in the Mesoscale Model Version 5 (MM5); and a prognostic scheme suggested by Noilhan and Planton that is being used in many mesoscale land surface models. In the first case, we showed that direct and indirect assimilation of surface observations can be efficiently used to modulate the Ma term and thus develop more realistic soil moisture feedback in the Carlson and Boland scheme. For the second (Noilhan and Planton) scheme, this assimilation approach was used to estimate adjustments for equitable evapotranspiration which were then translated into corresponding soil moisture adjustments in the soil moisture prognostic equations. Our technique was validated using a 1-D model along with special field observations over different landscapes with a variety of vegetation and soil moisture stress levels, and was found to be an efficient approach that can be easily adopted in various mesoscale models.

Alapaty, K.; Niyogi, D. S.

2001-05-01

368

Thermophysical Properties of the Lunar Surface from Diviner Observations  

NASA Astrophysics Data System (ADS)

Orbital thermal infrared measurements are sensitive to a variety of properties of the Moon's surface layer, including rock abundance, regolith cover and porosity, and small-scale surface roughness. With its multiple spectral channels and large dynamic temperature range, the Diviner Lunar Radiometer [1] on NASA's LRO spacecraft has enabled the first global, high-resolution maps of these important thermophysical properties. Here we present a summary of the results of Diviner's thermophysical investigation thus far. Maps of surface rock abundance show low typical values of <1% with higher abundances for recent craters and their blocky ejecta, as well as mass wasting on crater walls, rilles, and impact melt features [2]. The extent and abundance of surface rocks decrease systematically with crater age, and rocky surfaces are only preserved on the youngest craters (<1 Ga). We used nighttime regolith surface temperatures and eclipse cooling observations to constrain profiles of density and conductivity in the upper ~1 m, revealing a remarkably homogeneous subsurface structure [3]. Geographic variations in upper regolith density are nonetheless apparent. For example, buried rocks are suggested within young impact ejecta showing strong radar backscatter, high subsurface density, and a lack of surface rocks [2,4]. Rock fragmentation and regolith accumulation rates can be quantified by comparison of the Diviner data with published crater ages, yielding typical erosion rates which rapidly decrease from ~10 kg m-2 yr-1 for crater ages of ~1 Ma to ~1 mg m-2 yr-1 at ~1 Ga [4]. Variations in upper regolith density correlate with the ages of individual mare basalt units, suggesting this layer is actively processed by impacts on geologically short timescales, which may reveal age relationships previously unseen [5]. Vast cold regions surrounding fresh impact craters during lunar night (termed "cold spots") are only apparent in thermal infrared data [2]. These features cannot be explained by the emplacement of ejecta, and instead are well modeled by the in situ decompression of the top ~1-10 cm of regolith. Among a variety of explanations for this phenomenon, a model of grain lifting and turbulent mixing within an expanding vapor cloud best matches observations. The Diviner observations suggest impact vaporization leads to prominent yet ephemeral scars in the upper regolith that may be common on airless bodies in the Solar System. Surface roughness at scales smaller than the ~250 m Diviner footprint affects the measured spectral slope in brightness temperatures. We used Diviner brightness temperature spectra measured at a variety of solar illumination and viewing geometries to constrain and map the RMS slopes of the Moon's surface [6]. Due to the general increase in roughness at smaller scales, the RMS slopes of ~20-30° derived from Diviner data are likely dominated by the smallest scales where strong temperature gradients can exist, which are of order millimeters for typical lunar regolith [7,8]. Thus, these measurements complement those acquired by other techniques, such as laser altimetry [9], which typically measure surface roughness at scales larger than one meter. [1] Paige D. A., et al. (2009) Space Sci. Rev., 150, 135-160. [2] Bandfield J. L., et al. (2011) J. Geophys. Res., 116, E00H02. [3] Vasavada A. R., et al. (2012), J. Geophys. Res., 117, E00H18. [4] Ghent R., et al. (2012) AGU Fall Mtg., #P42A-07. [5] Hayne P. O., et al. (2013) Lunar and Planet. Sci. Conf. XLIV. [6] Hayne P. O., et al. (2013) Lunar and Planet. Sci. Conf. XLIII, #2829. [7] Buhl D., et al. (1968) J. Geophys. Res., 73, 5281-5295. [8] Williams J-P., et al. (2012) EPSC-DPS2011, vol. 6, 1678. [9] Rosenburg M. A., et al (2011), J. Geophys. Res., 116, E02001.

Hayne, Paul; Bandfield, Joshua; Vasavada, Ashwin; Ghent, Rebecca; Siegler, Matthew; Williams, Jean-Pierre; Greenhagen, Benjamin; Aharonson, Oded; Paige, David

2013-04-01

369

Forecast atmospheric surface fields versus in-situ and remote observations from Agulhas region to 57°S in 2008  

NASA Astrophysics Data System (ADS)

The region south of South Africa, encompassing the Agulhas Current and Retroflection, and part of the Southern Ocean, is known for its severe meteorological conditions. The in-situ observations are thus rare. Consequently, remote-sensing satellite observations and high-resolution weather forecasts at the ocean surface are difficult to assess. However, atmospheric data collected in the southern hemisphere summer of 2008 during the International Polar Year-BONUS-Good Hope cruise were used to validate two satellite data sets: the twice daily QuikSCAT winds and the daily OA flux data set of latent and sensible heat fluxes. The surface winds and heat fluxes forecasts produced by a regional atmospheric model were also assessed along the ship track. The two remote data sets exhibited a very good accordance with daily in-situ observations for wind speed and direction as well as for latent and sensible heat fluxes. Large differences in heat fluxes in both OAflux and the atmospheric model were observed when crossing the Subtropical Front and a warm eddy, as well as during a storm, when gale force winds reached more than 20 m/s. The two remote data sets were then used to assess the regional model forecasts over a larger area south of South Africa, not limited to the ship track. It was found that most of the model errors were located in a region north of the Subtropical Front, where the sea surface temperature used by the model was not accurate enough to reproduce the relevant mesoscale oceanic features. Finally, compared to in-situ and remote sensing observations, the numerical modelling weather forecast produced realistic atmospheric conditions over the sea south of the subtropical front.

Messager, C.; Faure, V.

2012-04-01

370

Surface orientation from texture: ideal observers, generic observers and the information content of texture cues.  

PubMed

Perspective views of textured, planar surfaces provide a number of cues about the orientations of the surfaces. These include the information created by perspective scaling of texture elements (scaling), the information created by perspective foreshortening of texels (foreshortening) and, for textures composed of discrete elements, the information created by the effects of both scaling and foreshortening on the relative positions of texels (position). We drive a general form for ideal observers for each of these cues as they appear in images of spatially extended textures, (e.g. those composed of solid 2-D figures). As an application of the formulation, we derive a set of 'generic' observers which we show perform near optimally for images of a broad range of surface textures, without special prior knowledge about the statistics of the textures. Using simulations of ideal observers, we analyze the informational structure of texture cues, including a quantification of lower bounds on reliability for the three different cues, how cue reliability varies with slant angle and how it varies with field of view. We also quantify how strongly the reliability of the foreshortening cue depends on a prior assumption of isotropy. Finally, we extend the analysis to a naturalistic class of textures, showing that the information content of textures particularly suited to psychophysical investigation can be quantified, at least to a first-order approximation. The results provide an important computational foundation for psychophysical work on perceiving surface orientation from texture. PMID:9747502

Knill, D C

1998-06-01

371

Land surface thermal environment during heat wave event measured by satellite observation  

NASA Astrophysics Data System (ADS)

In summer 2013, mainly from July to August, most parts of China continued to experience an unusually severe heat wave with exceptionally high air temperatures, based on the records measured at meteorological stations. As a supplement to the weather station networks, remotely sensed observation can quantify detailed variation of surface temperature at relatively high spatial resolution, owing to its ability to provide a complete and homogeneous data sources. In addition to the GHCN CAMS gridded land air surface temperature, land surface temperature products of MODIS including MOD11C3/MYD11C3 and MOD11A2/MYD11A2 were used to evaluate the anomaly of summertime thermal environment over the South China in 2013. To investigate the impacts of heat wave event on built environment, the MODIS Land Cover Type yearly product (MCD12Q1) was collected. Regional thermal anomaly was observed in both air and surface temperature measurements, especially for August. Statistics based on MOD11A2/MYD11A2 shows the spatio-temporal variation of land surface temperature at regional scale, and the heterogeneous characteristics in diurnal cycle are also shown. Compared with other types, the urban and built-up generally presents larger surface temperature at daytime. Detailed analyses were further conducted for three selected regions roughly covering the Yangtze River Delta, the Pearl River Delta, and the areas around Wuhan City respectively. Findings indicate that urban and built-up exhibits more distinct thermal contrast to its surroundings at daytime, in contrast to the situation at nighttime. This thermal contrast was defined as surface urban heat island intensity (UHII) calculated using a newly proposed procedure, in this paper. The UHII shows both time- and geography-dependent variations. Meanwhile, the UHII over medium and small cities was even more obvious and larger than that over megalopolitan areas. These preliminary findings suggest that land use and land cover changes as a consequence of rapid urbanization possibly gives positive feedback to warming anomaly during heat wave event. The exacerbated warming of built-up environment, not only over megalopolitan areas but also over medium and small cities, deserves our attention in urban management.

Chen, Feng; Yang, Song

2014-11-01

372

Surface contour radar observations of the directional wave spectrum during Fasinex  

NASA Technical Reports Server (NTRS)

The surface control radar (SCR), a 36-GHz computer-controlled airborne radar which generates a false-color coded elevation map of the sea surface below the aircraft in real time, is described. The SCR turned out to be ideal for documenting the wave spectra during Fasinex (the Frontal Air-Sea Interaction Experiment) due to its high spatial resolution and rapid mapping capability over extensive areas. Synoptic weather maps for February 15-18, 1986 are presented.

Walsh, E. J.; Hancock, D. W., III; Hines, D. E.; Swift, R. N.; Scott, J. F.

1988-01-01

373

Wacky Weather  

ERIC Educational Resources Information Center

What do a leaf blower, water hose, fan, and ice cubes have in common? Ask the students who participated in an integrative science, technology, engineering, and mathematics (I-STEM) education unit, "Wacky Weather," and they will tell say "fun and severe weather"--words one might not have expected! The purpose of the unit…

Sabarre, Amy; Gulino, Jacqueline

2013-01-01

374

Atomic force microscopic observation of surface-supported human erythrocytes  

NASA Astrophysics Data System (ADS)

The nanomechanical characteristics of the membrane cytoskeleton of human erythrocytes were studied using atomic force microscopy (AFM). The self-assembly, fine structure, cell diameter, thickness, and reticulate cytoskeleton of erythrocytes on the mica surface were investigated. The adhesive forces that correspond to the membrane elasticity of various parts of the erythrocyte membrane surface were measured directly by AFM to be 0.64±0.14nN for cell indentation, 4.2±0.7nN for cell hump, and 11.5nN for side waist, respectively. The deformation of erythrocytes was discussed. Standing waves on the membrane that were set up by increased AFM amplitude were observed. The propagating velocity on the erythrocyte membrane was estimated to be ˜2.02×10-2m/s. Liquid physiological conditions were considered throughout.

Ho, Mon-Shu; Kuo, Feng-Jia; Lee, Yu-Siang; Cheng, Chao-Min

2007-07-01

375

Coupled atmosphere and land-surface assimilation of surface observations with a single column model and ensemble data assimilation  

NASA Astrophysics Data System (ADS)

Numerical weather prediction and data assimilation models are composed of coupled atmosphere and land-surface (LS) components. If possible, the assimilation procedure should be coupled so that observed information in one module is used to correct fields in the coupled module. There have been some attempts in this direction using optimal interpolation, nudging and 2/3DVAR data assimilation techniques. Aside from satellite remote sensed observations, reference height in-situ observations of temperature and moisture have been used in these studies. Among other problems, difficulties in coupled atmosphere and LS assimilation arise as a result of the different time scales characteristic of each component and the unsteady correlation between these components under varying flow conditions. Ensemble data-assimilation techniques rely on flow dependent observations-model covariances. Provided that correlations and covariances between land and atmosphere can be adequately simulated and sampled, ensemble data assimilation should enable appropriate assimilation of observations simultaneously into the atmospheric and LS states. Our aim is to explore assimilation of reference height in-situ temperature and moisture observations into the coupled atmosphere-LS modules(simultaneously) in NCAR's WRF-ARW model using the NCAR's DART ensemble data-assimilation system. Observing system simulation experiments (OSSEs) are performed using the single column model (SCM) version of WRF. Numerical experiments during a warm season are centered on an atmospheric and soil column in the South Great Plains. Synthetic observations are derived from "truth" WRF-SCM runs for a given date,initialized and forced using North American Regional Reanalyses (NARR). WRF-SCM atmospheric and LS ensembles are created by mixing the atmospheric and soil NARR profile centered on a given date with that from another day (randomly chosen from the same season) with weights drawn from a logit-normal distribution. Three types of one-week long numerical experiments are performed: (a) free ensemble runs; (b) ensemble assimilation that directly impacts the atmospheric-state vector only; (c) ensemble assimilation that directly impacts the coupled atmospheric-LS-state vector. The WRF-SCM is run in two modes: with and without inclusion of externally imposed horizontal advection terms in the atmospheric column (derived from the NARR, too). Preliminary examination of analyses and 30-min forecasts of reference height temperature and moisture, soil temperature and moisture at four depths (0.05m, 0.25m, 0.7m and 1.5m), fluxes at the surface, and planetary boundary layer (PBL) height shows that: 1. Horizontal advection is important to the realism of PBL heights and fluxes in the "truth", and affects the depth of influence of the assimilation on the soil state; a deeper effect (that could be non-realistic) is more often observed when advection is not included. 2. Inclusion of soil variables in the state vector can be beneficial to estimates of soil temperature and moisture,of moisture- and net latent heat fluxes at the surface, and of atmospheric variables (for the latter especially when no advection is included), However, no benefit is observed on PBL heights. Further analysis and improvement of the WRF-SCM/DART system (in particular the treatment of advection) is under way.

Rostkier-Edelstein, Dorita; Hacker, Joshua P.; Snyder, Chris

2014-05-01

376

Evaluation of sea-surface salinity observed by Aquarius  

NASA Astrophysics Data System (ADS)

Sea-surface salinity (SSS) observed by Aquarius was compared with global observations from Argo floats and offshore moored buoys to evaluate the quality of satellite SSS data and to assess error structures. Aquarius products retrieved by different algorithms (Aquarius Official Release version 3.0 [V3.0], Combined Active-Passive [CAP] algorithm version 3.0, and Remote Sensing Systems test bed algorithm version 3) were compared. The Aquarius SSS was in good agreement with in situ salinity measurements for all three products. Root-mean-square (rms) differences of the salinity residual, with respect to Argo salinity, ranged from 0.41 to 0.52 psu. These three Aquarius products exhibit high SSS deviation from Argo salinity under lower sea-surface temperature conditions (<10°C) due to lower sensitivity of microwave emissivity to SSS. The CAP product deviates under strong wind conditions (>10 m s-1), probably due to model bias and uncertainty associated with sea-surface roughness. Furthermore, significant SSS differences between ascending (south-to-north) and descending (north-to-south) paths were detected. The monthly averaged Aquarius SSS (1° × 1° grid) was also compared with outputs from the ocean data optimal interpolation (OI) system operated by the Japan Agency for Marine-Earth Science Technology (JAMSTEC) and the ocean data assimilation system used by the Meteorological Research Institute, Japan Meteorological Agency (MRI/JMA). Negative bias, attributed to near-surface salinity stratification by precipitation, was detected in tropical regions. For 40°S-40°N, rms difference, with respect to JAMSTEC OI, is 0.27 psu for the V3.0, while the CAP product rms difference is only 0.22 psu, which is close to the Aquarius mission goal.

Abe, Hiroto; Ebuchi, Naoto

2014-11-01

377

Assimilation of Satellite-Derived Skin Temperature Observations into Land Surface Models  

NASA Technical Reports Server (NTRS)

Land surface (or "skin") temperature (LST) lies at the heart of the surface energy balance and is a key variable in weather and climate models. Here we assimilate LST retrievals from the International Satellite Cloud Climatology Project (ISCCP) into the Noah and Catchment (CLSM) land surface models using an ensemble-based, off-line land data assimilation system. LST is described very differently in the two models. A priori scaling and dynamic bias estimation approaches are applied because satellite and model LST typically exhibit different mean values and variability. Performance is measured against 27 months of in situ measurements from the Coordinated Energy and Water Cycle Observations Project at 48 stations. LST estimates from Noah and CLSM without data assimilation ("open loop") are comparable to each other and superior to that of ISCCP retrievals. For LST, RMSE values are 4.9 K (CLSM), 5.6 K (Noah), and 7.6 K (ISCCP), and anomaly correlation coefficients (R) are 0.62 (CLSM), 0.61 (Noah), and 0.52 (ISCCP). Assimilation of ISCCP retrievals provides modest yet statistically significant improvements (over open loop) of up to 0.7 K in RMSE and 0.05 in anomaly R. The skill of surface turbulent flux estimates from the assimilation integrations is essentially identical to the corresponding open loop skill. Noah assimilation estimates of ground heat flux, however, can be significantly worse than open loop estimates. Provided the assimilation system is properly adapted to each land model, the benefits from the assimilation of LST retrievals are comparable for both models.

Reichle, Rolf H.; Kumar, Sujay V.; Mahanama, P. P.; Koster, Randal D.; Liu, Q.

2010-01-01

378

Observation of 2nd Schumann eigenmode on Titan's surface  

NASA Astrophysics Data System (ADS)

This work presents the results obtained from an updated data analysis of the observations of extremely low frequency (ELF) electromagnetic waves performed with the HASI-PWA (Huygens Atmospheric Structure and Permittivity, Wave and Altimetry) instrumentation after Huygens Probe landing on Titan's surface in January 2005. The most significant signals observed at around 36 Hz throughout the descent in the atmosphere have been extensively analyzed for several years, and subsequently interpreted as the signature of a Schumann resonance, although the latter exhibits atypical peculiarities compared with those known on Earth. The usual depicting methods of space wave data used so far could not allow for retrieving the presence of weak signals when Huygens was at rest for 32 min on Titan's surface. Whereas the expected signal seems hidden within the instrumental noise, we show that a careful statistical analysis of the amplitude distribution of the 418 spectral density samples of the 36 Hz line reveals abnormal characteristics compared to other frequencies. This behavior is shown to occur under propitious circumstances due to the characteristics of the onboard data conversion processes into digital telemetry counts, namely 8-bit dynamic after logarithm compression of the DFT (Discrete Fourier Transform) of ELF waveforms. Since this phenomenon is observed only at the frequency bin around 36 Hz, we demonstrate that the Schumann resonance, seen in the atmosphere within the same band is still present on the surface, albeit with a much smaller amplitude compared to that measured before and a few seconds after the impact, because the electric dipole is thought to have been stabilized ten seconds later almost horizontally until the end of the measurements.

Béghin, C.; Wattieaux, G.; Grard, R.; Hamelin, M.; Lebreton, J. P.

2013-10-01

379

Observation of 2nd Schumann eigenmode on Titan's surface  

NASA Astrophysics Data System (ADS)

This works presents the results obtained from an updated data analysis of the observations of Extremely Low Frequency (ELF) electromagnetic waves performed with the HASI-PWA (Huygens Atmospheric Structure and Permittivity, Wave and Altimetry) instrumentation after Huygens Probe landing on Titan surface in January 2005. The most significant signals observed at around 36 Hz throughout the descent in the atmosphere have been extensively analyzed for several years, and subsequently interpreted as the signature of a Schumann resonance, although the latter exhibits atypical peculiarities compared with those known on Earth. The usual depicting methods of space wave data used so far could not allow retrieving the presence of weak signals when Huygens was at rest for 32 min on Titan's surface. Whereas the expected signal seems hidden within the instrumental noise, we show that a careful statistical analysis of the amplitude distribution of the 418 spectral density samples of the 36 Hz line reveals abnormal characteristics compared to other frequencies. This behavior is shown to occur under propitious circumstances due to the characteristics of the onboard data conversion processes into digital telemetry counts, namely 8-bit dynamic after logarithm compression of the DFT (Discrete Fourier Transform) of ELF waveforms. Since this phenomenon is observed only at the frequency bin around 36 Hz, we demonstrate that the Schumann resonance, seen in the atmosphere within the same band, is still present on the surface, albeit with a much smaller amplitude compared to that measured before and a few seconds after the impact, because the electric dipole is thought to have been stabilized ten seconds later almost horizontally until the end of the measurements.

Béghin, C.; Wattieaux, G.; Grard, R.; Hamelin, M.; Lebreton, J. P.

2013-04-01

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Experimental observation of dark solitons on the surface of water.  

PubMed

We present the first ever observation of dark solitons on the surface of water. It takes the form of an amplitude drop of the carrier wave which does not change shape in propagation. The shape and width of the soliton depend on the water depth, carrier frequency, and the amplitude of the background wave. The experimental data taken in a water tank show an excellent agreement with the theory. These results may improve our understanding of the nonlinear dynamics of water waves at finite depths. PMID:25166807

Chabchoub, A; Kimmoun, O; Branger, H; Hoffmann, N; Proment, D; Onorato, M; Akhmediev, N

2013-03-22