Note: This page contains sample records for the topic surface weather observations from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

History of surface weather observations in the United States  

Microsoft Academic Search

In this paper, the history of surface weather observations in the United States is reviewed. Local weather observations were first documented in the 17th Century along the East Coast. For many years, the progression of a weather observation from an initial reading to dissemination remained a slow and laborious process. The number of observers remained small and unorganized until agencies

Christopher A. Fiebrich

2009-01-01

2

History of surface weather observations in the United States  

NASA Astrophysics Data System (ADS)

In this paper, the history of surface weather observations in the United States is reviewed. Local weather observations were first documented in the 17th Century along the East Coast. For many years, the progression of a weather observation from an initial reading to dissemination remained a slow and laborious process. The number of observers remained small and unorganized until agencies including the Surgeon General, Army, and General Land Office began to request regular observations at satellite locations in the 1800s. The Smithsonian was responsible for first organizing a large "network" of volunteer weather observers across the nation. These observers became the foundation for today's Cooperative Observer network. As applications of weather data continued to grow and users required the data with an ever-decreasing latency, automated weather networks saw rapid growth in the later part of the 20th century. Today, the number of weather observations across the U.S. totals in the tens of thousands due largely to privately-owned weather networks and amateur weather observers who submit observations over the internet.

Fiebrich, Christopher A.

2009-04-01

3

Revised Uniform Summary of Surface Weather Observations (RUSSWO) - Kunsan AB, Korea.  

National Technical Information Service (NTIS)

This six-part statistical summary of surface weather observations for Kunsan AB, Korea contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values); (c) Surface ...

1977-01-01

4

Kunsan AB, South Korea Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

A six-part statistical data summary of surface weather observations for: Kusan AB, Korea. Summary consists of: PART A, Weather Conditions and Atmospheric Phenomena; PART B, Precipitation; PART C, Surface Winds; PART D, Ceiling and Visibility; PART E, Psyc...

1985-01-01

5

Kunsan AB, Korea Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

A six-part statistical data summary of surface weather observations for: Kunsan AB, Korea. Summary consists of: PART A, Weather Conditions and Atmospheric Phenomena; PART B, Precipitation; PART C, Surface Winds; PART D, Ceiling and Visibility; PART E, Psy...

1987-01-01

6

Lajes Fld, Azores. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Lajes Fld, Terceira, Azores. It contains the following parts (A) Weather conditions, Atmospheric Phenomena, (B) Precipitation, Snowfall and Snow Depth (daily amounts, and ex...

1980-01-01

7

Lajes Field, Terceira, Azores. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Lajes Field, Terceira, Azores. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and ...

1972-01-01

8

Revised Uniform Summary of Surface Weather Observations (RUSSWO) - Davis Monthan AFB Tucson, Arizona.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Davis Monthan AFB, Tucson, Arizona. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts...

1976-01-01

9

Kunsan AB, Kunsan, Korea. Revised Uniform Summary of Surface Weather Observations (Russwo) Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Kunsan AB, Kunsan, Korea. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extre...

1977-01-01

10

Williams Lake Apt, British Columbia, Canada. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Williams Lake Apt, British Columbia, Canada. It contains the following parts (A) Weather conditions, Atmospheric Phenomena, (B) Precipitation, Snowfall and Snow Depth (daily...

1971-01-01

11

Wright-Patterson AFB, Dayton, Ohio. Revised Uniform Summary of Surface Weather Observations. (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Wright-Patterson AFB, Dayton, Ohio. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts...

1980-01-01

12

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.

Crane, Peter

2004-05-01

13

National Weather Service Observing Handbook No. 1: Marine Surface Weather Operations.  

National Technical Information Service (NTIS)

In writing this new edition of NWS Observing Handbook No. 1, it has been our intent to include as much useful information as possible in the available space. The compact size and design, and field guide format, should allow for easy handling and quick ref...

2004-01-01

14

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

15

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

16

A revised empirical model to estimate solar radiation using automated surface weather observations  

Microsoft Academic Search

The transition from manual to automated weather observations at US National Weather Service Offices has compromised the ability to use these data as a means for estimating global horizontal and direct solar radiation. The creation of long term model-derived solar radiation climatologies continues to rely on the in situ cloud data that these observations provide, since homogeneous and readily available

Brian N. Belcher; Arthur T. DeGaetano

2007-01-01

17

Recovery of Global Surface Weather Observations for Historical Reanalyses and International Users  

NASA Astrophysics Data System (ADS)

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 past 200-250 years (http://reanalyses.org). The workshop improved integration of the 35-40 ACRE-linked international scientific projects, institutions, and organizations working toward these ends. The meeting highlighted the broad array and international usage of ACRE-facilitated data sets and reanalysis: the International Surface Pressure Databank (ISPD; http://dss.ucar.edu/datasets/ds132.0/), the International Comprehensive Ocean-Atmosphere Data Set (http:/icoads.noaa.gov/ICOADS;), and the 20th Century Reanalysis (20CR; http://www.esrl.noaa.gov/psd/data/20thC_Rean/). The need for more data recovery for all regions of the globe during the nineteenth and early twentieth centuries was emphasized. Many regional efforts for such recovery are under way. The Arctic and maritime regions were highlighted as particular areas needing attention. As a result of the meeting, connections with existing projects were made and new efforts were started to address these needs.

Allan, Rob; Compo, Gil; Carton, Jim

2011-05-01

18

Incipient space weathering observed on the surface of Itokawa dust particles.  

PubMed

The reflectance spectra of the most abundant meteorites, ordinary chondrites, are different from those of the abundant S-type (mnemonic for siliceous) asteroids. This discrepancy has been thought to be due to space weathering, which is an alteration of the surfaces of airless bodies exposed to the space environment. Here we report evidence of space weathering on particles returned from the S-type asteroid 25143 Itokawa by the Hayabusa spacecraft. Surface modification was found in 5 out of 10 particles, which varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles exist in a thin (5 to 15 nanometers) surface layer on olivine, low-Ca pyroxene, and plagioclase, which is suggestive of vapor deposition. Sulfur-free Fe-rich nanoparticles exist deeper inside (<60 nanometers) ferromagnesian silicates. Their texture suggests formation by metamictization and in situ reduction of Fe(2+). PMID:21868670

Noguchi, T; Nakamura, T; Kimura, M; Zolensky, M 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

2011-08-26

19

Initializing Weather Research and Forecasting (WRF) model with land surface conditions from the Terrestrial Observation and PredictionSystem (TOPS)  

NASA Astrophysics Data System (ADS)

Weather forecasting models have been shown to exhibit a strong sensitivity to land surface conditions, particularly soil moisture. However, the lack of robust estimates of soil moisture at appropriate time and space scales has been a persistent problem. Terrestrial Observation and Prediction System (TOPS) integrates surface weather observations and satellite data with ecosystem simulation models to produce spatially and temporally consistent nowcasts and forecasts of land surface conditions such as soil moisture, evapotranspiration, vegetation stress and photosynthesis. To extend TOPS capabilities beyond estimating ecosystem rocesses, we integrated TOPS with Weather Research Forecasting (WRF) model to evaluate the utility of TOPS-derived surface conditions such as soil moisture in weather forecasting. TOPS land surface schemes are based on a well-calibrated ecosystem model, Biome-BGC, for simulating water and carbon budgets. One of the advantages of TOPS is its flexibility, which enables it to ingest data from a variety of sensors and surface networks, and thus we can provide the surface conditions to users from historical to near real-time, and for spatial scales ranging from 1km and up. We ran the TOPS-WRF system over California for several days during 2007. The results show TOPS-WRF simulations are consistently better than default WRF simulations, particularly over the dry season when spatial variability in soil moisture becomes a significant factor in influencing local energy balance.

Hashimoto, H.; Wang, W.; Melton, F.; Milesi, C.; Michaellis, A.; Nemani, R.

2008-12-01

20

Estimates of diabatic wind speed profiles from near-surface weather observations  

Microsoft Academic Search

In this paper we analyse diabatic wind profiles observed at the 213 m meteorological tower at Cabauw, the Netherlands. It is shown that the wind speed profiles agree with the well-known similarity functions of the atmospheric surface layer, when we substitute an effective roughness length. For very unstable conditions, the agreement is good up to at least 200 m or

A. A. M. Holtslag

1984-01-01

21

AFM Observations of Weathering and Microbiological Alterations on the Surface of Calcite Buried in Arctic Soil (Spitsbergen)  

NASA Astrophysics Data System (ADS)

This study focused on the direct observation of chemical weathering and biological activity on mineral surfaces in the newly forming arctic soil of West Spitsbergen . Chemical weathering and soil forming processes associated with glaciers may affect several geochemical cycles including global carbon cycle and as a result have negative feedbacks on the global climate. Study areas are the foreland of the Werenskiold glacier, continuously retreating by several meters a year. Several samples of freshly cleaved calcite had been buried in the soils for one year. Samples were analyzed with the use of Atomic Force Microscopy (AFM). Results of AFM investigation show changes observed on a calcite samples located respectively about 2500 meters (sample calcite 1) and 100 m (sample calcite 2) from the glacier front as compared to a control sample calcite 0, that has never been exposed to glacier environment. Samples calcite 1 and calcite 2 were recovered from Spitsbergen after 1 year. Compared to the control sample calcite 0, which displays sharp edges and smooth surfaces, both field-treated samples calcite 1 and calcite 2 display rounded edges, irregular surfaces, numerous dissolution features and rounded pitches associated with bacterial activities. The observations suggest that both samples calcite 1 and 2 undergo intensive and rapid chemical and biological weathering when exposed to relatively unsaturated with respect to calcite glacial meltwaters. Several types of analyses have been applied to various regions and lines on the calcite surface. Selected regions on the calcite surface included (a) the entire area of the observed surface (b) top step region roughness, and (c) bottom step region roughness. Selected line parameters have been calculated along: (a) three randomly selected parallel lines, (b) top step line roughness, and (c) bottom step line roughness. Both surface area roughness and line roughness are calculated as the mean deviation of the height. Significant differences have been observed between the samples in calculated roughness parameters, with increase of these parameters ranging from 28% to 241% in calcite 1 located 2500 m from the glacier front and from 100% to 486% in calcite 2 located 100m from the glacier front, as compared to calcite 0. Roughness of the entire surface area for the control calcite 0 was 5.73nm, which increased by 28% in calcite 1 and by 100% in calcite 2. Top step edge roughness increases from calcite 0 (1.82 nm) by 241% to 6.2 nm in calcite 1 and by 486% to 8.84 nm in calcite 2. Bottom step edge roughness increases from 2.08 in calcite 0 by 98% to 4.52nm in calcite 1 and by 149% to 5.67 nm in calcite 2. Line roughness for calcite 0 is 3.26, which increased by 102% in calcite 1 and by 217% in calcite 2. Top step line roughness increases from 2.04 nm in calcite 0 by 191 % to 5.93 nm in calcite 1 and by 276% to 7.67nm in calcite 2. Bottom step line roughness increases from 2.28 nm in calcite 0 by 198% to 4.52 nm in calcite 1and by 249% to 5.67 nm in calcite 2. In calcite 0

Summers, S.; Matyjasik, M.; Inglefield, C.; Manecki, M.; Plonka, A.; Paget, C.; Park, C.

2008-12-01

22

Mechanism of feldspar weathering: Some observational evidence  

Microsoft Academic Search

Scanning electron microscopy (SEM) studies of sodic plagioclase and potassium feldspars isolated from soils indicate that the dissolution of feldspar during weathering occurs primarily at sites of excess energy on the crystal surface (for example, dislocations) and not by uniform attack over the entire surface of the mineral. As a result, distinctive etch pits develop on the feldspar surface. These

Robert A. Berner; George R. Holdren Jr.

1977-01-01

23

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

NASA Astrophysics Data System (ADS)

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 Martian weathering processes are based on the types of alteration products, the mineral assemblages, and derived chemistry. The spectroscopy of alteration minerals has been studied in detail for decades; however, detecting and identifying alteration products from remotely- sensed spectra of natural surfaces is complicated by microtextural mixing of rock-forming minerals, alteration products, and void space. We are investigating the effects that low-temperature weathering has on spectral observations in order to facilitate interpretation of spectroscopic data of Martian surfaces that may be weathered. Our approach has been to characterize the infrared spectra, mineral assemblages, and textures of weathering rinds and rock coatings formed on volcanic rocks in a variety of environments. This approach enables us to witness the spectral variability that results from weathering and tie it to differences in texture or mineralogical composition. More importantly, by examining numerous rinds and coatings, we can determine what effects are common to broader weathering phenomena. For instance, basalt weathering typically leads to systematic changes in silicate vibrational absorptions that can hamper spectral modeling techniques used to assess Martian data. In addition, weathered surfaces may show little evidence of hydrated minerals in near-infrared data. Another important component of our research is the use of controlled laboratory experiments designed to simplify, yet emulate, important attributes of the naturally weathered surfaces, in order to better constrain the spectral effects of weathering. Based on our findings regarding weathering mineral detectability, assertions that Mars has lacked aqueous weathering in its latter history may be incorrect. Rather, we suggest that volumetrically small amounts of high-silica weathering products formed in aqueous environments at middle and high latitudes and that this is consistent with spectroscopic observations of Mars.

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

2007-12-01

24

Weathering reactions and protection of wood surfaces  

Microsoft Academic Search

Wood materials are sensitive to outdoor weathering. The major significant factors causing weathering, such as solar radiation (ultraviolet light), moisture, and oxygen, have been investigated. It was found that UV light cannot penetrate deeper than 75 ..mu..m, while visible light can penetrate 200 ..mu..m into wood surfaces. Loss of brightness and change of color occurred when wood was exposed outdoors.

Hon

1983-01-01

25

Comparing simulated crop yields with observed and synthetic weather data  

Microsoft Academic Search

Stochastic weather generators have been used in the development of climate scenarios which are input to agricultural simulation models that assess the climate impacts on crop growth and production. The synthetic data generated by a stochastic weather generator only mimic the observed weather data, thus discrepancies between the synthetic and the observed weather data often exist. For example, interannual variability

Budong Qian; Reinder De Jong; Jingyi Yang; Hong Wang; Sam Gameda

2011-01-01

26

Thermal Weathering on Airless Planetary Surfaces  

Microsoft Academic Search

All airless planetary surfaces in our Solar System appear to be covered by a regolith layer. There are several general processes that could form such a regolith layer, including the rain of impactors on the surface, mass wasting, sublimation degradation, and physical weathering by thermal changes. Several of these processes have been well studied on icy satellites [e.g. Moore et

N. G. Pochat; S. Vance; G. C. Collins

2009-01-01

27

Weather observations through oceanic acoustic noise recorded by gliders  

NASA Astrophysics Data System (ADS)

Offshore estimates of the meteorological parameters are unfortunately spurious when considering in-situ observtions only due to obvious observational limitations while their use would allow to calibrate satellite observations and to have better weather forecasts, if assimilated in numerical weather forecasting systems. The WOTAN (Weather Observations through Acoustic Noise) approach may be used to fill these gaps if coupled to the Global Ocean Observing Sytem which has now a global coverage thanks to many autonomous observing platforms. In this study we show first results from acoustic records collected by gliders deployed in the northwestern Mediterranean Sea in the framework of MOOSE. We show that using 3 descriptors at 5kHz, 8kHz, and 20kHz allows to extract the intensity of the wind and the precipitation when the glider is at depth. This approach based on the method presented by Barry & Nuysten (2004) is compared with meterological data from coastal weather stations and the offshore meteorological buoys from Meteo-France. We also show that there is a vane effect with the tail of the glider while at surface which allows to estimate the direction of the wind every so often. These observations coupled with the in-situ profiles on temperature and salinity profiles can allow to better study air-sea interactions.

Cauchy, Pierre; Testor, Pierre; Guinet, Christophe; Gervaise, Cedric; Di Oro, Lucia; Ioana, Cornel; Mortier, Laurent; Bouin, Marie-Noelle; Beguery, Laurent; Klein, Patrice

2013-04-01

28

Summary of Meteorological Observations, Surface (SMOS) Rota, Spain.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1978-01-01

29

Summary of Meteorological Observations, Surface (SMOS), Meridian, Mississippi.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1978-01-01

30

Summary of Meteorological Observations, Surface (SMOS) South Weymouth, Massachusetts.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1978-01-01

31

Summary of Meteorological Observations, Surface (SMOS), Camp Pendleton, California.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1978-01-01

32

Summary of Meteorological Observations, Surface (SMOS), Midway Island.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1984-01-01

33

Thermal Weathering on Airless Planetary Surfaces  

NASA Astrophysics Data System (ADS)

All airless planetary surfaces in our Solar System appear to be covered by a regolith layer. There are several general processes that could form such a regolith layer, including the rain of impactors on the surface, mass wasting, sublimation degradation, and physical weathering by thermal changes. Several of these processes have been well studied on icy satellites [e.g. Moore et al. 1999]. Weathering of craters and regolith generation on airless bodies are presumed to result from micrometeorite impacts. For instance, one could look at examples of smooth terrain on the moon and try to explain smooth terrain on Callisto by small impacts, but the crater density is well below equilibrium. This led Moore et al. (1999) to state, “…some other process is dominating its surface layer.” The question is: what process could this be? Moore et al. (1999) argue that sublimation and deposition is a dominant weathering process occurring on Callisto, but it may not be the only regolith-generating process. Vance et al. (2007) adapted a thermal expansion anisotropy and mismatch driven fracturing model for a matrix of square grains. Recently we have been looking at the stress at grain boundaries in this model. This stress term is dependent on the grain size and rate of temperature change at the surface of the body. The question we are trying to answer is whether the stress generated at grain boundaries during diurnal heating and cooling is enough to generate and propagate fractures in the surface material. We started by developing a one dimensional finite difference thermal model for the near-surface environment on an airless body, insulated on the bottom boundary and driven by insolation and radiation to space on the surface. We also assumed that density was constant with depth. The program can take the different parameters for each body (e.g. the bolometric albedo and distance from the sun) and calculate the temperature change at any depth over a diurnal cycle at any latitude. Ice is a simple material to consider in models of thermal weathering. We have developed a thermal model for airless planetary surfaces in our Solar System. By linking this thermal model to the grain boundary stress model, we are able to place limits on the smallest grain size that permits thermal weathering, and the depth to which cracking will occur on different icy bodies in our solar system. For instance, we found that cracking can occur on the surfaces of Ganymede and Callisto for grain sizes > 0.5 microns. Thermal weathering may be an important process contributing to regolith generation on airless planetary surfaces. This near-surface process may help to speed up other processes like mass wasting and sublimation degradation. We will present maps of susceptibility to thermal cracking for airless planetary surfaces in our solar system at the meeting and compare to what is known about the regolith. References: Moore et al. (1999) Icarus 140, p. 294-312; Vance et al. (2007) Astrobiology 7, p. 987-1005.

Pochat, N. G.; Vance, S.; Collins, G. C.

2009-12-01

34

Observing Space Weather towards building Predictive Capabilities  

NASA Astrophysics Data System (ADS)

Simultaneous data from multi-point space missions operating in the Sun-Earth system in conjunction with dedicated ground- based networks have facilitated major steps towards the quantification of space weather processes, better understandings of their impacts on the various high level systems of modern societal infrastructure and fundamental developments in space weather forecasting. Through the EU FP7 program and the ESA Space Situational Awareness (SSA) program several dedicated space weather projects and studies have currently been initiated, such as the AFFECTS (Advanced Forecast For Ensuring Communications Through Space), aiming in establishing prototype space weather services, instruments and missions as precursors of a future space weather operational system. This presentation provides an overview of the ongoing European activities, upcoming challenges and opportunities for international collaborations.

Bothmer, Volker

2012-07-01

35

Easter Island, Chile Limited Surface Observations Climatic Summary (LISOCS). Parts A, C-F.  

National Technical Information Service (NTIS)

A statistical data summary of surface weather observation climatology for: Easter Island Chile. This summary is similar to the Revised Uniform Summary of Surface Weather Observations (RUSSWO), but is based on data collected from limited-duty weather obser...

1985-01-01

36

Weather  

NSDL National Science Digital Library

This project will help you understand the weather and investigate weather interactively. What are the components of weather? How do you measure weather? Investigate the WeatherScholastic: Weather WatchWeatherWeather Center for Our 4th Grade ...

Lai, Ms.

2007-02-08

37

Modelling of sample surface temperature in an outdoor weathering test  

Microsoft Academic Search

A heat transfer model is constructed to derive the surface temperature of specimens in outdoor weathering. Data on thermal properties of materials and routinely collected weather data are used as inputs for the model. The model is validated against surface temperature data measured on samples of 11 different materials exposed to natural outdoor weathering in Jokioinen, Finland, over a period

P. Bijl; A. Heikkilä; S. Syrjälä; A. Aarva; A. Poikonen

2011-01-01

38

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

Education, Terc. C.; Littell, Mcdougal

2003-01-01

39

Observation impact on forecast parameters of mesoscale weather systems  

NASA Astrophysics Data System (ADS)

The sensitivity of forecast outputs to observational inputs is quantified by utilizing the adjoint formulations of a numerical weather prediction model and data assimilation system. The reduction in short term forecast error due to the assimilation of observations is investigated using a limited area model with horizontal grid spacings appropriate for mesoscale weather systems. The relative impact of observations can vary greatly depending on the physical location of the model's domain and the area over which the error is calculated. For example, observations from radiosondes and aircraft are important for reducing error over the eastern United States, but satellite derived winds and surface reports over the eastern Pacific Ocean are most important if the target area is over the western US. There are subtle differences in the observation impacts on forecasts utilizing a range of horizontal grid spacings (20-60 km). In a few cases for the smaller grid spacings, the adjoint of the limited area model fails to account for a satisfactory amount of the nonlinear model error. Impacts on metrics other than forecast error will also be presented.

Amerault, C. M.

2011-12-01

40

Surface Observation Climatic Summaries for Kunsan AB, Korean.  

National Technical Information Service (NTIS)

Surface observation climatic summaries (SOCS) provide statistical climatic summaries of surface weather observations taken and recorded at specified observing stations. Hourly observations are summarized from a 10-year period of record. Information is sum...

1991-01-01

41

Martian Weather Analysis and Forecasts from Multiple Spacecraft Observations  

NASA Astrophysics Data System (ADS)

There is now a small fleet of spacecraft orbiting Mars with instruments that make observations relevant to the atmosphere. Chief among these is the Mars Global Surveyor (MGS) Thermal Emission Spectrometer that takes up to 6 nadir infrared spectra every three seconds from a low, circular, polar orbit, with occasional limb scans. The MGS also includes a Horizon Sensor that makes side-looking broadband 15 micrometer measurements, and a Radio Science experiment that determines the atmospheric structure from occasional radio occultations. From a different orbit, at a different time of day, the Mars Odyssey THEMIS instrument makes downward looking broadband 15 micrometer measurements. The Mars Express will add infrared and ultraviolet observations of the atmosphere from a highly elliptical orbit. All of these spacecraft carry cameras that observe ice and dust clouds. While none of the instruments or observing patterns is optimized for atmospheric science, the sum total of the data is more than enough to specify all of the parameters in a low resolution Martian general circulation model. We can therefore make use of data assimilation techniques (like those used in operational weather prediction on Earth) to deduce the full atmospheric state (4-dimensional temperatures, geopotential heights, winds, water vapor, dust, clouds, and surface pressure). The payoff is enormous: retrievals of atmospheric parameters are no longer independent of each other (and underdetermined), but are constrained by physical laws; the data assimilation product is a compact physical state that can reproduce the much more extensive spectral data (to within the observational errors); calibration can be addressed from the internal consistency of the observations of a given instrument; validation (in the absence of ground truth) is performed by detailed comparison of the data from different instruments and different platforms (even when there are no co-incident observations); data quality control emerges naturally from the observation weighting scheme which rejects data that disagrees violently with both other measurements and the forecast model; and real-time weather forecasts can be made available for a host of operational purposes (aerobraking, aerocapture, gliding, ballooning, dust storm warnings). All of these are made practical---given the limited computational resources that can be devoted to Martian weather forecasting---by an observation space sequential assimilation technique, using a transformed extended Kalman filter that weights both model forecasts and observational errors by agreement with the data. Forecast errors are less than 4 K and should improve with more sophisticated predictive models.

Houben, H.

2004-05-01

42

Air Masses and Fronts - Fronts and the Surface Weather Map.  

National Technical Information Service (NTIS)

Explains the use of surface weather maps and shows how fronts form from warm and cold air. Shows how weather patterns appear on the map and discusses general wind directions, wind shifts, low pressure trough, frontal surfaces, and temperature changes. Als...

1994-01-01

43

Weather Observation Systems and Efficiency of Fighting Forest Fires  

NASA Astrophysics Data System (ADS)

Weather observation is an essential component of modern forest fire management systems. Satellite and in-situ based weather observation systems might help to reduce forest loss, human casualties and destruction of economic capital. In this paper, we develop and apply a methodology to assess the benefits of various weather observation systems on reductions of burned area due to early fire detection. In particular, we consider a model where the air patrolling schedule is determined by a fire hazard index. The index is computed from gridded daily weather data for the area covering parts Spain and Portugal. We conduct a number of simulation experiments. First, the resolution of the original data set is artificially reduced. The reduction of the total forest burned area associated with air patrolling based on a finer weather grid indicates the benefit of using higher spatially resolved weather observations. Second, we consider a stochastic model to simulate forest fires and explore the sensitivity of the model with respect to the quality of input data. The analysis of combination of satellite and ground monitoring reveals potential cost saving due to a "system of systems effect" and substantial reduction in burned area. Finally, we estimate the marginal improvement schedule for loss of life and economic capital as a function of the improved fire observing system.

Khabarov, N.; Moltchanova, E.; Obersteiner, M.

2007-12-01

44

Weathering of chemically modified wood surfaces  

Microsoft Academic Search

Summary   Scots pine wood veneers were acetylated to weight gains of 5, 10, 15 or 20% and exposed to natural weathering. Veneers acetylated\\u000a to low weight gains of 5 and 10% and exposed to the weather showed greater losses in mass and tensile strength due to increased\\u000a delignification and depolymerisation of cellulose than similarly exposed, untreated controls. Acetylation to 20%

P. D. Evans; A. F. A. Wallis; N. L. Owen

2000-01-01

45

Infrasonic Observation of a Severe Weather System.  

National Technical Information Service (NTIS)

The coherent atmospheric pressure waves traveling at sonic velocities from a squall line storm 20-75 km. distant were observed in detail for a period of 100 min. The measurements indicate that the infrasonic wave was generated in or near the leading edge ...

V. H. Goerke M. W. Woodward

1966-01-01

46

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 ...

Hyde, Mrs.

2007-02-08

47

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 ...

Bullough, Ms.

2010-06-24

48

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 ...

Stearns, Ms.

2008-10-25

49

Edmonton IAP, Canada Limited Surface Observations Climatic Summary (LISOCS). Parts 1-5.  

National Technical Information Service (NTIS)

A statistical data summary of surface weather observation climatology for: Edmonton International Airport Canada. This summary is similar to the Revised Uniform Summary of Surface Weather Observations (RUSSWO), but is based on data collected from limited-...

1986-01-01

50

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

51

National Weather Service  

MedlinePLUS

... CURRENT CONDITIONS Radar Climate Monitoring River Levels Observed Precipitation Surface Weather Upper Air Marine and Buoy Reports ... Weather Current Outlook Maps Drought Fire Weather Fronts/Precipitation Maps Current Graphical Forecast Maps Rivers Marine Offshore ...

52

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 ...

Williams, Ms.

2005-10-25

53

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.

Gore, Pamela

1995-08-29

54

Weather  

NSDL National Science Digital Library

Meteorologists study the weather by recording and analyzing data. You can become an amateur meteorologist by building your own weather station and keeping a record of your measurements. After a while, you\\'ll notice the weather patterns that allow meteorologists to forecast the weather. Tasks: 1. As a group you will build a weather station outside. 2. Your group will build instruments to measure the weather. 3. Each person will record the data in personal weather journals. Process: 1.Since weather happens outside, you\\'ll need to make ...

Tuttle, Rachelle

2005-10-25

55

Weathering of rock surfaces in the Zermatt-Saas area (Swiss Alps), weathering rinds resulting from water-rock interaction  

NASA Astrophysics Data System (ADS)

The geogene component of the chemical composition of most surface waters is contributed by interaction of precipitation water with silicate rocks exposed in the catchment. Mineral solubility and rates of dissolution reaction control the water-rock interaction process. We have studied the chemical composition of surface waters and weathering crusts of exposed rocks in high Alpine catchments of the Zermatt-Saas area (Swiss Alps). Surface water in this area is predominantly controlled by the interaction of meteoric water with the exposed rocks. Water-rock interaction acquires solutes for the surface waters but also chemically and mineralogically alters the near surface volume of the exposed rocks. Exposed rocks in Zermatt-Saas area include various metamorphic oceanic rocks of the Zermatt-Saas ophiolite unit (ZSU) and continental rocks of the nappes above and below the ZSU. During early stages of Alpine orogeny, the ZSU has been subducted and transformed to eclogites and other high-pressure rocks. Fragments of the oceanic material were returned to the surface as serpentinites, eclogites, eclogite facies metagabbro and metasediments. At many outcrops exposed rocks show distinct signs of surface alteration and are coated with rust-colored weathering crusts. These crusts often display a rough surface texture and are porous as a result of intense chemical weathering. For the purpose of this study we collected typical samples of strongly weathered common rocks of the area, including serpentinite, greenschist and gneiss. The sampling locations were typically close to bodies of surface water. We found that the penetration depth of the interaction between surface water and exposed rocks ranges from 0 - 20 mm. In some strongly altered rocks the interface of the alteration reaction between altered and fresh rock was located several cm below the surface. The presence and thickness of reaction crusts is limited by access of water to the reaction sites (reaction front), specifically to the amount of reaction-created porosity and other water-conducting features. Six pairs of carefully separated weathered and fresh parts of rocks were analyzed by X-ray fluorescence to study the bulk composition evolution. 15 thin sections from the weathered part of the rock samples were examined by microscopy. Clear alteration textures were observed on most reactive minerals, like olivine, chlorite, serpentine, pyrite and others. Reaction related chemical changes of such minerals were analyzed by electron microprobe. Weathered rocks from the same lithology have texturally and chemically very similar alteration crusts throughout the area. In metabasaltic rocks like greenschist, chlorite was found to be very finely intergrown with Fe-oxyhydroxide on a µm scale in the alteration zone close to and at the weathered surface. In ultramafic rocks like serpentinite, the alteration from olivine to chrysotile was commonly found. The bulk composition differences between weathered and fresh parts of the rock samples can be correlated with the chemical characteristics of surface water from the respective catchments.

Zhou, Wei; Bucher, Kurt

2010-05-01

56

Summary of Meteorological Observations, Surface (SMOS), McMurdo Station, Antarctica.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1978-01-01

57

Surface reactions during the early stages of weathering of albite  

Microsoft Academic Search

The aim of this study is to gain a better understanding of the nature and distribution of surface species occurring during the initial stage of weathering of albite. Instead of the classical acidbase titration experiments used extensively in previous work, the surface of freshly ground mineral was titrated by adding increasing amounts of solid to pure water. The aqueous phase

Roland Wollast; Lei Chou

1992-01-01

58

Weather.  

ERIC Educational Resources Information Center

|This theme issue of "The Goldfinch" focuses on weather in Iowa and weather lore. The bulletin contains historical articles, fiction, activities, and maps. The table of contents lists: (1) "Wild Rosie's Map"; (2) "History Mystery"; (3) "Iowa's Weather History"; (4) "Weather Wonders"; (6) "Seasonal Jobs"; (7) "Fiction: Winter Courage"; (8) "Stayin'…

Ruth, Amy, Ed.

1996-01-01

59

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, Jr. , M. F.

1992-01-01

60

Personal Computers, Weather Observations, and the National Climatic Data Center  

Microsoft Academic Search

The personal computer (PC) has become an important part of meteorological observing, telecommunications, forecasting, research, and data-management systems. The National Climatic Data Center (NCDC) is the nation's quality-control and archival facility for weather data. NCDC's digital archive consists of more than 200 data sets which are stored on over 50 000 reels of high-density magnetic tape. Its size and complexity

Richard Heim Jr.

1988-01-01

61

Surface weather features associated with freezing precipitation and severe in-flight aircraft icing  

Microsoft Academic Search

Surface observations of freezing precipitation and pilot reports of severe in-flight aircraft icing for the continental United States are compared to the location of surface weather features, including airmasses of different origin and position relative to fronts, low-pressure centers and troughs. Statistics are calculated to determine where freezing precipitation and severe aircraft icing occur most often, and are produced most

Ben C Bernstein; Tiffany A Omeron; Marcia K Politovich; Frank McDonough

1998-01-01

62

Weather  

NSDL National Science Digital Library

The National Oceanic and Atmospheric Administration (NOAA) provides these two Websites on weather. The first site serves as a major hub for information related to weather, with links to primary data sources, forecasts, maps, images (such as the latest satellite imagery for North America), and a wealth of other data, including space weather. Researchers will also find links to national weather research centers and other related agencies.

63

Observations and Modeling of Space Weather Impacts on the Earth  

NASA Astrophysics Data System (ADS)

``Space weather'' refers to conditions in the solar wind, magnetosphere, ionosphere, and upper atmosphere, that influence space-borne and ground-based technological systems and can endanger human space exploration. These effects are caused by variations in solar photon and particle radiation due to flares and coronal mass ejections, and changes in the solar/interplanetary magnetic field, that impact the magnetosphere and ionosphere. Space weather can initiate satellite failures, interfere with radio communications, cause navigation errors, disrupt electrical power distribution systems, and expose astronauts to dangerous levels of radiation. Mitigation requires both a better understanding of the space environment, and developing the ability to forecast conditions in space. The development of first-principles numerical models of the solar-terrestrial system gives us insight into the causes and nature of these phenomena, and holds the promise of ultimately being able to acquire a short-term predictive capability for some of them. This presentation will describe what we do and don't understand about the basic physics behind space weather, discuss some of its aspects and effects, and describe the latest observational and modeling efforts

Solomon, Stanley C.

2006-10-01

64

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

65

Observations of upper atmospheric weather during solar minimum winter  

NASA Astrophysics Data System (ADS)

The paper reports on a wide variety of thermospheric and ionospheric observations from three consecutive January World Day campaign periods. Despite remarkably similar geophysical conditions characterizing the in situ forcing of the upper atmosphere during these solar minimum campaigns, significant variability is found in the observations of the ionosphere and thermosphere, particularly at low latitudes in the American sector. Further observational evidence is presented of the unexpected exospheric temperature suppression at low latitudes initially reported by Hagan and Salah (1988). The paper discusses the lower and upper atmospheric coupling mechanisms of plausible importance to the interpretation of the observed thermospheric weather patterns. Evidence is reported that lower thermospheric nitric oxide number density and upward propagating atmospheric tides affected the thermospheric energy and momentum budgets during the campaign periods.

Hagan, M. E.; Barth, C. A.; Tobiska, W. K.; Manson, A. H.; Vincent, R. A.; Bounsanto, M. J.; Burnside, R. G.; Wickwar, V. B.

1992-04-01

66

Observations of upper atmospheric weather during solar minimum winter  

SciTech Connect

The authors report on a wide variety of thermospheric and ionospheric observations from three consecutive January World Day campaign periods. Despite remarkably similar geophysical conditions characterizing the in situ forcing of the upper atmosphere during these solar minimum campaigns, they find significant variability in the observations of the ionosphere and thermosphere particularly at low latitudes in the American sector. In addition, they present further observational evidence of the unexpected exospheric temperature suppression at low latitudes initially reported by Hagran and Salah (1988). They discuss the lower and upper atmospheric coupling mechanisms of plausible importance to the interpretation of the observed thermospheric weather patterns. They report evidence that lower thermospheric (NO) (nitric oxide number density) and upward propagating atmospheric tides affected the thermospheric energy and momentum budgets during the campaign periods.

Hagan, M.E. (Massachusetts Inst. of Tech., Westford (United States) National Center for Atmospheric Research, Boulder, CO (United States)); Barth, C.A. (Univ. of Colorado, Boulder (United States)); Tobiska, W.K. (Univ. of California, Berkeley (United States)); Manson, A.H. (Univ. of Saskatchewan, Saskatoon (Canada)); Vincent, R.A. (Univ. of Adelaide (Australia)); Buonsanto, M.J. (Massachusetts Inst. of Tech., Westford (United States)); Burnside, R.G. (Cornell Univ., Arecibo (Puerto Rico)); Wickwar, V.B. (Utah State Univ., Logan (United States))

1992-04-01

67

Recent Near-Neutral Chemical Weathering of Martian High-Latitude Surfaces  

NASA Astrophysics Data System (ADS)

Recent scientific investigations of Mars, including those conducted by TES, OMEGA, and the MER lander missions, have expanded the discussion about aqueous alteration on Mars. Results from these missions indicate that the styles and/or intensity of water-rock interactions on Mars have changed over time, and they provide evidence for geographical differences in weathering typically associated with latitude. Work that we have done on the spectroscopy of terrestrial weathering rinds and rock coatings indicates that small volumes of weathering products mixed with primary minerals considerably change thermal emission spectra of volcanic rocks. Based on that work, we suggest that low-intensity chemical weathering leading to the formation of small volumes of weathering products can explain the global distribution of TES observations. Whereas MER results indicate acidic alteration at low latitudes since the late Noachian, we suggest that major surface- mineralogical differences observed by TES (and broadly corroborated by OMEGA) may be due to near-neutral pH chemical weathering, pedogenically driven by near-surface pore waters at mid-to-high latitudes.

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

2006-12-01

68

Observations of Heterogeneous Clouds and Weather in Substellar Atmospheres  

NASA Astrophysics Data System (ADS)

Atmospheres of cool brown dwarfs and gas giant planets share important similarities such as low temperatures, a rich molecular chemistry, condensate clouds, and rapid rotation. The combination of condensate clouds and rapid rotation has long motivated searches for weather phenomena on cool brown dwarfs. However, until recently, observations have failed to show compelling evidence for heterogeneous cloud features or giant storms that are commonplace within our own Solar System. Here we describe the most comprehensive variability survey of cool brown dwarfs to date. Our J-band search has targeted 50 isolated brown dwarfs over 60 nights at the DuPont 2.5-m telescope at Las Campanas with high cadence, high-precision photometric sequences, and is complemented by follow-up observations in additional bands in order to characterize the nature of the variations. Our data suggest that heterogeneous cloud features are responsible for variability (in one case as large as 30%) in a subset of partially cloudy brown dwarfs. Our results highlight the limitations of current 1D model atmospheres for brown dwarfs and extrasolar giant planets, and can be used to inform higher-dimensional modeling. In addition, variable brown dwarfs may provide a means of mapping winds and weather in ultracool atmospheres, thereby providing an empirical anchor for atmospheric circulation models in a new (non-irradiated, higher mass, rapidly rotating) physical regime.

Radigan, Jacqueline; Jayawardhana, R.; Lafreniere, D.; Artigau, E.

2011-09-01

69

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

70

Surface radiation balance in Antarctica as measured with automatic weather stations  

Microsoft Academic Search

We present 4 years of near-surface radiation balance observations of four Antarctic automatic weather stations (AWS). The AWS are situated along a traverse line in Dronning Maud Land, connecting the coastal ice shelf and the inland plateau via the katabatic wind zone, covering the three major climate regimes of East Antarctica. Important differences in the radiation balance of the three

Michiel van den Broeke; Carleen Reijmer; Roderik van de Wal

2004-01-01

71

Evaluation of high-resolution weather forecasts in tropics using satellite passive millimeter-wave observations  

Microsoft Academic Search

This paper evaluates high-resolution weather forecasts in tropics. The fifth-generation NCAR\\/Penn State Mesoscale Model, MM5, was used to forecast 79 storms spanning a year over Thailand and nearby regions at 5-km resolution. MM5 forecasted brightness temperatures and those coincidentally observed by the passive millimeter-wave Advanced Microwave Sounding Units (AMSU) aboard NOAA-16 satellite were compared. MM5-forecasted surface precipitation rate, peak vertical

Chinnawat Surussavadee

2011-01-01

72

Effect of accelerated weathering on surface chemistry of modified wood  

Microsoft Academic Search

In this study, the effects of UV-light irradiation and water spray on colour and surface chemistry of scots pine sapwood samples were investigated. The specimens were treated with chromated copper arsenate (CCA), a metal-free propiconazol-based formulation, chitosan, furfuryl alcohol and linseed and tall oils. The weathering experiment was performed by cycles of 2h UV-light irradiation followed by water spray for

Ali Temiz; Nasko Terziev; Morten Eikenes; Jonas Hafren

2007-01-01

73

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

74

AMSU-A Land Surface Emissivity Estimation for Numerical Weather Prediction Assimilation Schemes  

Microsoft Academic Search

This study describes the work performed at the European Centre for Medium-Range Weather Forecasts (ECMWF) to estimate the microwave land surface emissivities at Advanced Microwave Sounding Unit (AMSU)-A frequencies within the specific context and constraint of operational assimilation. The emissivities are directly calculated from the satellite observations in clear-sky conditions using the surface skin temperature derived from ECMWF and the

Catherine Prigent; Frédéric Chevallier; Fatima Karbou; Peter Bauer; Graeme Kelly

2005-01-01

75

Effect of accelerated weathering on surface chemistry of modified wood  

NASA Astrophysics Data System (ADS)

In this study, the effects of UV-light irradiation and water spray on colour and surface chemistry of scots pine sapwood samples were investigated. The specimens were treated with chromated copper arsenate (CCA), a metal-free propiconazol-based formulation, chitosan, furfuryl alcohol and linseed and tall oils. The weathering experiment was performed by cycles of 2 h UV-light irradiation followed by water spray for 18 min. The changes at the surface of the weathered samples were characterised by Fourier transform infrared spectroscopy (FT-IR); colour characterizations were performed by measuring CIELab parameters. The results show that all treatment methods except chitosan treatment provided lower colour changes than the control groups after 800 h exposure in weathering test cycle, but differences between chitosan and control were also small. The lowest colour changes were found on linseed oil (full cell process) and CCA treated wood. FT-IR results show that oil treatment (linseed and tall oil) decreased the intensities of a lignin specific peak (1500 1515 cm-1). Absorption band changes at 1630 1660 cm-1 were reduced by all treatments.

Temiz, Ali; Terziev, Nasko; Eikenes, Morten; Hafren, Jonas

2007-04-01

76

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; Mifflin, Houghton

77

Lightning Sensors for Observing, Tracking and Nowcasting Severe Weather  

PubMed Central

Severe and extreme weather is a major natural hazard all over the world, often resulting in major natural disasters such as hail storms, tornados, wind storms, flash floods, forest fires and lightning damages. While precipitation, wind, hail, tornados, turbulence, etc. can only be observed at close distances, lightning activity in these damaging storms can be monitored at all spatial scales, from local (using very high frequency [VHF] sensors), to regional (using very low frequency [VLF] sensors), and even global scales (using extremely low frequency [ELF] sensors). Using sensors that detect the radio waves emitted by each lightning discharge, it is now possible to observe and track continuously distant thunderstorms using ground networks of sensors. In addition to the number of lightning discharges, these sensors can also provide information on lightning characteristics such as the ratio between intra-cloud and cloud-to-ground lightning, the polarity of the lightning discharge, peak currents, charge removal, etc. It has been shown that changes in some of these lightning characteristics during thunderstorms are often related to changes in the severity of the storms. In this paper different lightning observing systems are described, and a few examples are provided showing how lightning may be used to monitor storm hazards around the globe, while also providing the possibility of supplying short term forecasts, called nowcasting.

Price, Colin

2008-01-01

78

Observations from remote weather stations in San Francisco Bay, California  

USGS Publications Warehouse

Weather data collected at three remote weather stations in the San Francisco Bay estuarine system between November 1979 and September 1981 are compiled in this report. Measurements include average and maximum wind speed, wind direction, air temperature, atmospheric pressure, and irradiance. Data are presented in time-series plots with each graph covering one calendar month. Daily averages of all measurements are tabulated.

Gartner, J. W.; Cheng, R. T.

1983-01-01

79

Forecasting Dew Duration at Pendleton, Oregon, Using Simple Weather Observations  

Microsoft Academic Search

The importance of dew to agriculture, together with the absence of dew measurements at standard weather station sites, resulted in the development of predictive models for dew formation in the Umatilla River Basin, Oregon. Meteorological data were obtained at the Pendleton Experiment Station in close proximity to dew-measurement devices, and from the Pendleton National Weather Service Office. Dew measurements, made

Michael J. Crowe; Stella Melugin Coakley; Robert G. Emge

1978-01-01

80

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...

81

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

82

A statistical model for road surface friction forecasting applying optical road weather measurements  

NASA Astrophysics Data System (ADS)

Road surface friction is defined as the grip between car tyre and underlying surface. Poor friction often plays a crucial role in wintertime car accidents. Friction can decrease dramatically during snowfall or when wet road surface temperature falls below zero. Even a thin layer of ice or snow can decrease friction substantially increasing the risk of accidents. Many studies have shown that road surface temperature, road conditions and friction can fluctuate dramatically within short distances under specific weather situations. Friction or grip can be improved with road maintenance activities like salting and gritting. Salting will melt the ice or snow layer, whereas gritting will improve the grip. Salting is effective only above -5C temperatures. Light snowfall together with low temperatures can result in very slippery driving conditions. Finnish Road Administration's observing network covers c. 500 road weather stations in Finland. Almost 100 of them are equipped with optical sensors (in winter 2008-2009). The number of optical sensors has increased remarkably during past few years. The optical measuring devices are Vaisala DSC111 sensors which measure the depth of water, snow and ice on the road surface and also produce an estimate of the state of road and prevailing friction. Observation data from road weather stations with optical sensors were collected from winter 2007/08, and a couple of representative (from a weather perspective) stations were selected for detailed statistical analysis. The purpose of the study was to find a statistical relationship between the observed values and, especially, the correlation between friction and other road weather parameters. Consequently, a model based on linear regression was developed. With the model friction being the dependent variable, the independent variables having highest correlations were the composite of ice and snow (water content) on the road, and the road surface temperature. In the case of a wet road surface, the amount of water was the best predictor for friction. The models were tested with an independent sample from winter 2008/09. Finnish Meteorological Institute (FMI) has been running an operational road weather prediction model for about ten years. The model predicts e.g. the road surface temperature and the layers of snow, ice and water on the road. With the addition of the statistical friction model, road surface friction will be a new forecast parameter. There are, however, some challenges to be solved before operational applicability. A major issue is how to take road maintenance activities, and especially the salting, into account. This study is carried out within the EU/FP7 Project ROADIDEA, where the major frame of reference is to develop new and innovative products for traffic and transport sectors.

Hippi, M.; Juga, I.; Nurmi, P.

2009-09-01

83

Design of a Digital Simulation of the Polar Planimeter for Calculating Areas of Echoes from Radar Weather Observations.  

National Technical Information Service (NTIS)

The effort discussed in the report was to fulfill a requirement for expediently analyzing data on radar weather prediction techniques. Data is recorded at various radar stations, which make hourly weather observations on the local weather activity within ...

R. G. Kelley

1968-01-01

84

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

85

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 ...

Caitlin, Ms.

2009-10-21

86

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

87

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

88

Solar Observations What is needed for Space Weather Monitoring ?  

Microsoft Academic Search

The Sun is our star and the prime source of space weather. Over the past decades, space missions with sophisticated payloads have led us to discover and explore the dynamics of our Sun and its impact on the heliosphere in unprecedented detail. A new level of understanding of the physics behind solar activity has been achieved and state-of-the-art missions like

Volker Bothmer

2010-01-01

89

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

90

Meteorological Parameters Derived from Space-Based Observing Systems, During the Global Weather Experiment and After.  

National Technical Information Service (NTIS)

Global coverage by geostationary and polar orbiting meteorological satellites during the Global Weather Experiment (GWE) for data collection from in situ platforms and remote sensing of the atmosphere and the earth's surface is reviewed. Quantitative data...

D. S. Johnson

1986-01-01

91

Toward Application of Lightning Observations to Weather Forecasts and Warnings  

NASA Astrophysics Data System (ADS)

Once lightning mapping systems became fast enough to locate lightning in real or near-real time, it became possible to consider applications of lightning data to weather operations. The first system to be used routinely in such a way was the LLP direction-finder network deployed around 1980 by the Bureau of Land Management to help detect range and forest fires started by cloud-to-ground lightning. In 1987, a federal interagency group collaborated with the State University of New York at Albany to put together a trial National Lightning Detection Network for a three-year evaluation of possible applications to weather operations. During this trial, the National Weather Service determined that the lightning ground-strike data are useful for detecting the presence, configuration, and evolution of storms and storm systems, and so subsequently procured lightning strike mapping data for federal use that has continued to the present. Research since then has suggested that detection of positive cloud-to-ground lightning may also be useful, when combined with radar data, to help identify some severe storms, though the conditions under which this is possible are still being investigated. Furthermore, cloud-to-ground flash data can be assimilated into forecast models to improve the initial conditions, and hence the forecasts, of the models. More recently technology has advanced to the point that mapping all types of lightning is feasible. Because typically more than 70% of the lightning flashes produced by a storm do not strike ground, such technologies, at a minimum, would increase sampling rates to identify thunderstorms more quickly and reliably. However, different types of lightning also provide different information about storms. Cloud-to-ground lightning tends to indicate the formation and descent of precipitation, while cloud flash rates appear to be associated more closely with updraft and graupel evolution. Research is underway to determine and quantify these relationships better and to develop techniques for using such relationships to warn of and forecast hazardous weather.

Macgorman, D. R.

2002-12-01

92

Comparing the simulation of climate impacts on crop yields with observed and synthetic weather data  

NASA Astrophysics Data System (ADS)

Stochastic weather generators have been used extensively in the development of climate scenarios, especially at the daily or shorter time scales, for the use as climate input to agricultural simulation models that evaluate the climate impacts on crop yields. Because generated synthetic weather data mimic the observed weather data, discrepancies between the two datasets often exist. For example, interannual variability in the synthetic data is often found to be weaker than in the observed data, i.e., the well-known overdispersion problem. Therefore, it is important to evaluate if the climate impact models are sensitive to such discrepancies between synthetic weather data and observed ones. In this study, we used a stochastic weather generator (AAFC-WG) to generate 300-yr long synthetic weather data for two Canadian sites (Swift Current on the Canadian Prairies and London in southern Ontario), based on the observed weather data for the baseline period of 1961-1990. The Decision Support System for Agrotechnology Transfer (DSSAT) v4.0 was employed to simulate crop growth and yield. Spring wheat at Swift Current and grain corn at London were simulated by the DSSAT cropping system model with three major soil types at each location, using the 30-yr observed weather data and 300-yr synthetic data, respectively. Statistical tests were performed to investigate whether differences (both mean and variance) of the simulated crop yields between the simulations with observed and synthetic weather data are statistically significant or not. Results demonstrated that the differences in simulated crop yields are often not statistically significant when synthetic weather data are used to substitute the observed data.

Qian, B.; de Jong, R.; Yang, J.; Wang, H.; Gameda, S.

2010-12-01

93

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.

94

Validation of the Space Weather Modeling Framework using observations from CHAMP and DMSP  

Microsoft Academic Search

The Space Weather Modeling Framework (SWMF) is a flexible framework for space weather simulation, which can couple magnetosphere and ionosphere processes. This work compares ionospheric outputs from SWMF with magnetic and plasma observations from CHAMP and DMSP satellites under both quiet and storm conditions, emphasizing the dependence of the model's performance for various magnetic local times, solar wind conditions, and

H. Wang; A. J. Ridley; H. Lühr

2008-01-01

95

Coastal observations of weather features in Senegal during the African Monsoon Multidisciplinary Analysis Special Observing Period 3  

NASA Astrophysics Data System (ADS)

During 15 August through 30 September 2006 (Special Observing Period 3, SOP3), key weather measurements are obtained from ground and aircraft platforms during the African Monsoon Multidisciplinary Analysis campaign. Key measurements are aimed at investigating African easterly waves (AEWs) and mesoscale convective systems in a coastal environment as they transition to the eastern Atlantic Ocean. Ground and aircraft instruments include polarimetric radar, a coarse and a high-density rain gauge network, surface chemical measurements, 12 m meteorological measurement, broadband IR, solar and microwave measurements, rawinsonde, aircraft dropsonde, lidar, and cloud radar measurements. Ground observations during SOP3 show that Senegal was influenced by 5 squall lines, 6 Saharan air layer intrusions, and 10 AEWs. Downstream tropical cyclones developed were associated with the passage of four AEWs. FA-20 aircraft measurements of microphysical aspects of 22 September squall line and several nondeveloping AEWs over the extreme eastern Atlantic Ocean are presented.

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.; Ndiaye, S. A.; Deme, A.

2010-09-01

96

Does mineral surface area affect chemical weathering rates?  

Microsoft Academic Search

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,

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

2010-01-01

97

Weather and climate analyses using improved global water vapor observations  

NASA Astrophysics Data System (ADS)

The NASA Water Vapor Project (NVAP) dataset is a global (land and ocean) water vapor dataset created by merging multiple sources of atmospheric water vapor to form a global data base of total and layered precipitable water vapor. Under the NASA Making Earth Science Data Records for Research Environments (MEaSUREs) program, NVAP is being reprocessed and extended, increasing its 14-year coverage to include 22 years of data. The NVAP-MEaSUREs (NVAP-M) dataset is geared towards varied user needs, and biases in the original dataset caused by algorithm and input changes were removed. This is accomplished by relying on peer reviewed algorithms and producing the data in multiple “streams” to create products geared towards studies of both climate and weather. We briefly discuss the need for reprocessing and extension, steps taken to improve the product, and provide some early science results highlighting the improvements and potential scientific uses of NVAP-M.

Vonder Haar, Thomas H.; Bytheway, Janice L.; Forsythe, John M.

2012-08-01

98

Radiation Chemical Weathering of Water-Rich Surfaces  

NASA Astrophysics Data System (ADS)

Water ice is known to exist on nineteen different moons of the four giant planets, and also on Pluto's moon, the rings of Saturn, trans-Neptunian objects, and comets. Other condensed volatiles have also been detected on many of these objects. These solar system ices exist in a variety of radiation environments that can include magnetospheric ions and cosmic rays. To study the radiation chemical weathering of water-rich ices, we record changes in the mid-IR spectra of low-temperature thin ice films during ion bombardment. We have completed a variety of MeV proton irradiation experiments on both pure H2O and H2O-dominated ices containing CO2, CO, CH4, and NH3. This talk will focus on the radiation chemical processes that lead to the formation of H2O2 (a detected radiation product on Europa, (Carlson et al. 1999)) and carbonic acid, H2CO3 (a candidate whose IR spectrum is similar to observed features on Callisto, (Carlson, 2001)). We will identify other radiation products that are most likely to be observed from mixtures such as H2O + CH4, H2O + CO, H2O + NH3. The role of CO2 in the formation of O2 will also be discussed. This research is funded through NRA 344-33-01 and 344-02-57 Carlson et al. (1999) Science, 283, 2062 Carlson (2001) private communication

Moore, M. H.; Hudson, R. L.; Ferrante, R. F.

2002-12-01

99

Martian Weathering Environments of the Amazonian Indicated by Correlated Morphologic and Spectral Observation in Acidalia Planitia  

NASA Astrophysics Data System (ADS)

While much attention has been given to chemical alteration and the state of water on early Mars, it remains important to understand aqueous processes throughout Martian history, including the recent geologic past. It has been suggested that the Amazonian was marked primarily by anhydrous, oxidative weathering because Amazonian surfaces, such as the northern plains, lack hydration features in near-infrared spectra [1]. But high-silica materials (Surface Type 2, ST2) discovered by the Thermal Emission Spectrometer [2] that occur in the northern plains attest to aqueous alteration of silicate minerals. The questions are when did this occur and by what process? ST2 correlates spatially with outflow sediments and high-silica materials may have formed in large amounts of water related to outflow flooding events of the late Hesperian [3,4]. ST2 also may correspond to global ice-rich mantles, indicating formation in icy environments related to geologically recent climate fluctuations [3]. Can these very different mechanisms and environments be discerned? In a global study of TES spectra, Rogers et al. (2007) [5] found significant spectral differences between ST2 surfaces in northern and southern Acidalia Planitia that occur near 40-50° N. Several geomorphic transitions occur across latitudes, and many of these are directly or potentially related to Amazonian periglacial activity and occur in the 40-50° N range. This potential link between composition and periglacial morphology needs further exploration. We examined this relationship from 40-50° N in Acidalia Planitia, using Thermal Emission Imaging System (THEMIS) multispectral data to measure the local spectral properties of the surface. We identified a boundary between two surface spectral types that match closely the spectra of north and south Acidalia derived by Rogers et al. [2007]. This boundary is diffuse, occurring between 47-48° N in our study region in western Acidalia, and correlates with observed morphologic and thermophysical differences. Close examination of those surfaces with High Resolution Imaging Science Experiment (HiRISE) images shows that the area north of the boundary is a modified version of the southern surface, subdued and overprinted by periglacial polygonal ground. Thus, we think that ground ice has modified the surface morphology and, furthermore, that periglacial processing also modified the silicate composition of the northern surface materials. Weathering that created the northern Acidalia composition involved ground ice, and was likely similar to weathering in Antarctic soils, in which silica is mobilized by thin water films and deposited as gels [6]. By this mechanism, aqueous weathering on Mars has probably persisted into, and throughout, the Amazonian. References: [1] Bibring et al. (2006) Science, 312, 400-404. [2] Bandfield et al. (2000) Science, 287, 1626-1630. [3] Wyatt et al. (2004) Geology, 32, 645-648. [4] Tanaka et al. (2005) USGS Sci. Invest. Map 2888. [5] Rogers et al. (2007) J. Geophys. Res.,112, E02004. [6] Ugolini and Anderson (1973), Soil Sci., 105, 461-470.

Kraft, M. D.; Rogers, D.; Fergason, R. L.; Michalski, J. R.; Sharp, T. G.

2009-12-01

100

Characterization of bacterial community inhabiting the surfaces of weathered bricks of Nanjing Ming city walls.  

PubMed

Nanjing Ming city wall, one of the important historic heritages in China, has greatly suffered weathering. Microbes play an important role in the weathering of historic buildings. However, little is known about the microbial community inhabiting naturally weathered brick minerals and their roles in the mineral weathering. To examine the associations between microorganisms and brick weathering process, we compare the phylogenetic diversity, abundance, community structure, and specific functional groups of bacteria existing in weathered bricks by using a coupled approach involving cultivation-independent analysis of denaturing gradient gel electrophoresis (DGGE) as well as cultivation-based analysis of Si-releasing bacteria. DGGE and sequence analyses show that the bacterial communities were different along a weathering gradient and the abundance of bacterial communities positively and significantly correlates with the extent of brick weathering. Laboratory brick mineral dissolution experiments indicate that bacteria isolated from the surfaces of weathered brick were very effective in enhancing brick dissolution. Phylogenetic analyses show that the weathered bricks were inhabited by specific functional groups of bacteria (Bacillus, Massillia, Brevibacillus, Glacialice, Acinetobacter, Brachysporum, and Achromobacter) that contribute to the brick weathering. PMID:21112073

Qi-Wang; Ma, Guang-You; He, Lin-Yan; Sheng, Xia-Fang

2010-11-26

101

Surface roughness and color characteristics of wood treated with preservatives after accelerated weathering test  

Microsoft Academic Search

Wood samples treated with ammonium copper quat (ACQ 1900 and ACQ 2200), chromated copper arsenate (CCA), Tanalith E 3491 and Wolmanit CX-8 have been studied in accelerated weathering experiments. The weathering experiment was performed by cycles of 2h UV-light irradiation followed by water spray for 18min. The changes on the surface of the weathered samples were characterized by roughness and

Ali Temiz; Umit C. Yildiz; Ismail Aydin; Morten Eikenes; Gry Alfredsen; Gürsel Çolakoglu

2005-01-01

102

Surface characterization of weathered wood-plastic composites ...  

Treesearch

High-density polyethylene (HDPE) based WPCs made from modified wood flour ... The study showed that longer exposure time caused higher oxidation, lower wood ... wood flour, color fading, mechanical properties, polyethylene, weathering, ...

103

Weather Specialist/Aerographer's Mate.  

ERIC Educational Resources Information Center

|This course trains Air Force personnel to perform duties prescribed for weather specialists and aerographer's mates. Training includes meteorology, surface and ship observation, weather radar, operation of standard weather instruments and communications equipment, and decoding and plotting of surface and upper air codes upon standard maps and…

Chanute AFB Technical Training Center, IL.

104

Characterizing the process and quantifying the rate of subaerial rock weathering on desert surfaces using roughness analysis  

NASA Astrophysics Data System (ADS)

Subaerial weathering of rocks is a common process observed on desert surfaces on Earth and other planetary terrestrial surfaces such as on Mars. On Earth, this weathering process has been previously identified as one of the key erosion agent driving geomorphic surface evolution and the development of desert pavements. And yet, fundamental aspects of the process, such as the relative contribution of the different weathering modes that drive it (e.g., mechanical breakdown of rocks, chemical weathering, aeolian abrasion and exfoliation) as well as the rate by which this weathering process occurs have not been systematically examined. Here, we present a new approach for quantitatively addressing these fundamental aspects of process geomorphology on desert surfaces. We focus here on co-genetic desert alluvial surfaces of different ages, i.e. alluvial chronosequences, which provide excellent recorders for the evolution of boulder-strewn surfaces into smooth desert pavements through in-situ subaerial weathering of rocks. Our approach combines independent measures of two different surface attributes: High resolution (mm-scale) 3D ground-based laser scanning (LiDAR) of surface micro-topography, and numerical dating of surface age. Roughness analysis of the LiDAR data in power spectral density (PSD) space allows us to characterize the geometric manifestation of rock weathering on the surface and to distinguish between the different weathering modes. Numerical age constraints provide independent estimates for the time elapsed since the process began. Accordingly, we are able to constrain surface roughness evolution on alluvial fan desert chronosequences through time, and present PSD analysis of surface roughness as a new quantitative tool to examine the process of subaerial rock weathering in desert environments. In this study we present results from two late Quaternary alluvial chronosequences along the Dead Sea Transform in the hyper-arid Negev desert of southern Israel. LiDAR scanning was applied on representative areas (~30-50 m2) of 10 separate surfaces ranging from rough Holocene surfaces to fairly smooth surfaces with well-developed pavements displaying an OSL age of 87 kyr. We find typical and recurring time-dependent changes in the offset as well as shape of the PSD curves in both chronosequences: PSD offset is continuously reduced over time reflecting the overall reduction in the amplitude of roughness at all wavelengths. The PSD curves display progressive moderation of slopes at the longer wavelengths with the moderation point itself systematically shifted to shorter wavelengths. This characteristic evolution of PSD offset and slope moderation at longer wavelengths reflects the typical break up of boulder-sized clasts through time as the surfaces mature into well-developed desert pavements and points towards mechanical breakdown as the dominant weathering mode. In addition, we are able to determine the rate by which the larger clasts are removed from the system. We build on these new insights into process and rate of rock weathering to propose PSD analysis of surface roughness as a complementary method for constraining the age of desert alluvial surfaces in places where 'conventional' dating cannot be applied.

Mushkin, Amit; Sagy, Amir; Trabelci, Eran

2013-04-01

105

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.

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

2012-01-01

106

Change of black shale organic material surface area during oxidative weathering: Implications for rock-water surface evolution  

NASA Astrophysics Data System (ADS)

Black shale oxidative weathering plays a significant role in a variety of processes including acid mine drainage and atmospheric CO 2 control. The modeling of weathering is highly dependent on reactive surface area. In this study it is shown that black shale oxidative weathering is regulated mainly by the external, geometrical surface area of rock polyhedrons and the organic matter's (OM) internal surface area. The internal rock surface area decreases dramatically during OM dissolution from ˜15 m 2/g to ˜5 m 2/g. A linear relationship was found between the decrease of internal rock surface area and quantity of OM dissolved. Optical roughness analyses of black and bleached shale surface area reveal the formation of macropores due to the dissolution of mesoporous and probably microporous OM. However, due to deconsolidation, the geometrical external rock polyhedron surface area increases during weathering. Black shale polyhedrons show a doubling of their external surface area as OM decreases. This provokes an increase of the shale volume which is easily accessible by fluids. The increase of the external rock surface area seems to be self-accelerating during weathering. The upscaling of external and internal rock surface area evolution during weathering presented in this study demonstrates the possible application of these results to the improved understanding of a chemical transport in a variety of natural systems.

Fischer, Cornelius; Gaupp, Reinhard

2005-03-01

107

Research of polarization imaging detection method for water surface target in foggy weather  

NASA Astrophysics Data System (ADS)

According to problems of the intensity imaging target detection on water surface in foggy weather such as the indistinction of the target and greatly loss of the target detail, a target detection method based on the target polarization characteristics for water surface target in foggy weather is proposed in this paper. To validate the method's effectiveness, the indoor experiment is performed by using the simulation environment in foggy weather and the outdoor experiment is performed by using the water surface real fog environment. A lot of different intensity images and polarization images are got and then analysed and compared. The experimental results demonstrate that the polarization imaging detection can effectively obtain the polarization information of targets on water surface, and we can detect the water surface targets in foggy weather by polarization information retrieving and the target information restoring.

Wang, Feng; Yin, Cheng-liang; Wang, Yong

2013-09-01

108

18 years of Energy Balance Observations on Antarctica using Automatic Weather Stations  

NASA Astrophysics Data System (ADS)

Since 1995, the Institute for Marine and Atmospheric research, Utrecht (IMAU) operates Automatic Weather Stations (AWS) on Antarctica. A total of 17 stations of which three located on the Larsen ice shelf, one on Berkner Island, and 13 in Dronning Maud Land (DML), are or have been operational. The obtained records are fairly complete and between 4 and 14 years long. The observed quantities include air temperature, relative humidity, wind speed, air pressure and incoming and outgoing short- and longwave radiation. These data are used to calculate the surface turbulent heat fluxes and study the temporal and spatial variability of meteorological quantities and the surface energy budget. The turbulent heat fluxes are calculated using the aerodynamic 'bulk' method between a single AWS sensor level and the surface, where the surface temperature is calculated using a surface energy balance closure assumption for a surface skin layer. At all sites the annual mean net radiation is negative and the near-surface air is on average stably stratified. The negative net radiative flux is largely balanced by a positive sensible heat flux. The latent heat flux is on average small and negative indicating a small net mass loss through sublimation. The spatial variations reflect differences in elevation, cloud cover and wind speed. The temporal variability on annual time scales is fairly similar from site to site. The three sites with the longest records (>8 years) show an increase in annual average temperature. The largest temperature change occurs in DML on the Plateau. For this station the annual mean fluxes also show a trend towards less negative net radiation, smaller sensible heat flux and larger latent heat flux. However, these trends are not significant.

Reijmer, Carleen; Van den Broeke, Michiel; Smeets, Paul; Boot, Wim

2013-04-01

109

Effects Of Fungal-Mineral Interactions On Chemical Weathering And Denudation Processes - Observations From Experimental Ecosystems  

NASA Astrophysics Data System (ADS)

A mesoscale (`sandbox') lysimeter experiment was performed at Hubbard Brook Experimental Forest, New Hampshire, to study plant-growth influences on chemical weathering and chemical denudation. Weathering was estimated by mass balance for 5 and 15-year intervals, and denudation was monitored as the product of drainage flow and concentration for 20 years in large (7.5x7.5x1.5m) fully lined sandboxes a.) planted with red pine (Pinus resinosa Ait.), and b.) kept free of vascular vegetation. Mass-balance equations included base cations (Ca, Mg, and K) in precipitation inputs and drainage outputs, and changes of base cation contents in biomass and soil. Scanning Electron Microscopy (SEM) and Environmental-SEM studies of the coarse sandbox soils were used for detection of mycorrhizal fungal association with roots, fungal development and attachment features on mineral grain surfaces. In the non-vascular system chemical weathering and denudation fluxes did not change significantly during the monitored period, but denudation fluxes were 1.3-1.4 times higher than weathering fluxes. In the vascular ecosystem the chemical weathering flux was 3 and 1.8 times greater than the denudation flux over 5 and 15 years, respectively, but both rates decreased over time. In our experiment the pines retarded denudation and accelerated weathering relative to the nonvascular system, thereby increasing available nutrient pools. The SEM and ESEM studies indicated more weathering features (etch pits, cracks, wholes, channels, and secondary minerals) in the mineral surfaces of the vascular system associated with the mycorrhizal fungal hyphae. Profiles of base-cation concentrations in soil water suggest that hyphal-mineral surface attachment might also insulate cation uptake from bulk soil water and hydrologic loss. The sandbox study offers insight into short-term effects of ecosystems on global biogeochemical processes.

Balogh, Z.; Keller, C.; Dickinson, J.

2003-12-01

110

On The Dynamical Basis of Targeting Weather Observations  

Microsoft Academic Search

We developed and tested a new electromagnetic sounding system. It is called EM- ACROSS (ElectroMagnetic - Accurately Controlled Routinely Operated Signal Sys- tem), and originally Ogawa and Kumazawa (1996) proposed. The essential points of this method are the transmission of accurately controlled electromagnetic waves, and precise synchronization between the source and observation points, and acquisition the transfer function between the

I. Szunyogh; A. V. Zimin; D. J. Patil; B. R. Hunt; E. Kalnay; E. Ott; J. A. Yorke

2002-01-01

111

Martian Weathering Environments of the Amazonian Indicated by Correlated Morphologic and Spectral Observation in Acidalia Planitia  

Microsoft Academic Search

While much attention has been given to chemical alteration and the state of water on early Mars, it remains important to understand aqueous processes throughout Martian history, including the recent geologic past. It has been suggested that the Amazonian was marked primarily by anhydrous, oxidative weathering because Amazonian surfaces, such as the northern plains, lack hydration features in near-infrared spectra

M. D. Kraft; D. Rogers; R. L. Fergason; J. R. Michalski; T. G. Sharp

2009-01-01

112

On The Dynamical Basis of Targeting Weather Observations  

NASA Astrophysics Data System (ADS)

We developed and tested a new electromagnetic sounding system. It is called EM- ACROSS (ElectroMagnetic - Accurately Controlled Routinely Operated Signal Sys- tem), and originally Ogawa and Kumazawa (1996) proposed. The essential points of this method are the transmission of accurately controlled electromagnetic waves, and precise synchronization between the source and observation points, and acquisition the transfer function between the source and receivers. This transfer function includes the information of the area where the electromagnetic waves propagates. We developed hardware to establish an EM-ACROSS system. To generate the accu- rately controlled source signal and to synchronize the receivers with the source, we utilize GPS clock. The time-keeping for the transmission and data recordings is better than micro seconds. We examined this system by the transmission from the current dipole (moment 200Am) at the frequencies below 100Hz and the observations at the distances up to 3km in Tono area. We transmitted the controlled source signal which the signal-to-noise ratio of the spectrum from 200 seconds data attained up to 104. The accuracy of the synchronization was ascertained in data stacking of the received signal. The longer stacking reduced the error of the received signal as theoretically expected. From the observed transfer function, the resistivity of the experimental site was estimated as about 100 m, which is the typical value at the test site. We represent that the exploration using the accurately controlled electromagnetic sig- nal is realized. We come to convince ACROSS has a potential for explorations.

Szunyogh, I.; Zimin, A. V.; Patil, D. J.; Hunt, B. R.; Kalnay, E.; Ott, E.; Yorke, J. A.

113

Indication of Insensitivity of Planetary Weathering Behavior and Habitable Zone to Surface Land Fraction  

NASA Astrophysics Data System (ADS)

It is likely that unambiguous habitable zone terrestrial planets of unknown water content will soon be discovered. Water content helps determine surface land fraction, which influences planetary weathering behavior. This is important because the silicate-weathering feedback determines the width of the habitable zone in space and time. Here a low-order model of weathering and climate, useful for gaining qualitative understanding, is developed to examine climate evolution for planets of various land-ocean fractions. It is pointed out that, if seafloor weathering does not depend directly on surface temperature, there can be no weathering-climate feedback on a waterworld. This would dramatically narrow the habitable zone of a waterworld. Results from our model indicate that weathering behavior does not depend strongly on land fraction for partially ocean-covered planets. This is powerful because it suggests that previous habitable zone theory is robust to changes in land fraction, as long as there is some land. Finally, a mechanism is proposed for a waterworld to prevent complete water loss during a moist greenhouse through rapid weathering of exposed continents. This process is named a "waterworld self-arrest," and it implies that waterworlds can go through a moist greenhouse stage and end up as planets like Earth with partial ocean coverage. This work stresses the importance of surface and geologic effects, in addition to the usual incident stellar flux, for habitability.

Abbot, Dorian S.; Cowan, Nicolas B.; Ciesla, Fred J.

2012-09-01

114

Severe weather observed by infrasound, lidar and airglow measurements during the ARISE OHP Campaign  

NASA Astrophysics Data System (ADS)

In the frame of the ARISE project dedicated to provide a new 3D image of the atmospheric dynamics in the different atmospheric layers, an observation campaign using infrasound, lidar and airglow measurements started in July 2012 in the Observatoire de Haute Provence. This paper is dedicated to present first observations of severe weather, including sprite producing thunderstorms and a tornado. The study considers acoustic waves but also focuses on gravity waves at the origin of larger scale disturbances. The coupling between atmospheric layers during these events is analyzed using numerical weather simulations. The presentation discusses the benefits of the use of the three different technologies for a better description of these events.

Blanc, Elisabeth; Farges, Thomas; Le Pichon, Alexis; Hauchecorne, Alain; Wüst, Sabine; Heinrich, Philippe; Keckhut, Philippe; Costantino, Lorenzo; Bittner, Michael; Schmidt, Carsten

2013-04-01

115

Spectral evidence of size dependent space weathering processes on asteroid surfaces  

Microsoft Academic Search

Most compositional characterizations of the minor planets are derived from analysis of visible and near-infrared reflectance spectra. However, such spectra are derived from light which has only interacted with a very thin surface layer. Although regolith processes are assumed to mix all near-surface lithologic units into this layer, it has been proposed that space weathering processes can alter this surface

M. J. Gaffey; J. F. Bell; R. H. Brown; T. H. Burbine; J. L. Piatek; K. L. Reed; D. A. Chaky

1993-01-01

116

Advances in Doppler Weather Radar Observing Methods and Data Processing Techniques.  

National Technical Information Service (NTIS)

A continuing objective of the Navy-sponsored, Doppler radar studies has been to develop the operational utility of the radar, both as a weather research tool and as an observing instrument useful for specialized, short-term forecasting. To fill this role ...

C. C. Easterbrook

1971-01-01

117

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

118

Spatial interpolation of atmospheric pressure observations from automatic weather stations in complex alpine terrain  

Microsoft Academic Search

ARPA Lombardia is the environmental protection agency for the administrative region Lombardia and manages a high resolution meteorological network composed by hundreds of automatic weather stations. Among these, about one hundred are equipped with barometers. The historical barometric dataset is however affected by many large systematic errors. Thus, an effort is done to recover information from such observations. A bias

C. Lussana; F. Uboldi; M. R. Salvati; M. Ranci

2010-01-01

119

NEXRAD Weather Radar Observations of the 2006 Augustine Volcanic Eruption Clouds  

NASA Astrophysics Data System (ADS)

The 2006 eruption of Augustine Volcano, Alaska provided an exceptional opportunity to detect and measure explosive volcanic events and to track drifting volcanic clouds using WRS-88D (NEXRAD) weather radar data. Radar data complemented the real-time seismic monitoring by providing rapid confirmation of ash generation and cloud height. The explosive phase of the eruption consisted of thirteen discrete Vulcanian explosions from January 11 to 28, with seismic durations that ranged from one to eleven minutes. The ash columns and drifting clouds from all of the events were observed via a NEXRAD located 185 km NE of the volcano on the Kenai Peninsula (site PAHG). The radar was operated in both precipitation and clear air modes, resulting in a temporal resolution of 4.1 to 10 minutes per complete scan, respectively. Scan elevation angles for the radar beam centroid varied slightly depending upon mode of operation, but values of 0.5, 1.5, 2.5, and 3.5 degrees were typically used, corresponding to altitudes over the volcano of 3.8, 7.2, 10.5, and 13.8 km above sea level. Estimates of eruption cloud height were made by the National Weather Service (NWS) Anchorage Forecast Office using range-height indication cross-sections and radar echo tops (the altitude of the +18.5 dBZ reflectance surface). The observed cloud heights typically ranged from 7.5 to 10.5 km above sea level, with the exception of the January 17 event which briefly had an echo top of about 14 km. Most of the eruption clouds reached their maximum height in the first scan in which they were visible, suggesting an energetic and impulsive initial event, and were at lower heights in subsequent views. These height estimates may be minimum values because very fine-grained ash at the top of eruption clouds has low radar reflectance, and thus may not be observed. Height estimates were rapidly communicated to the NWS Alaska Aviation Weather Unit and the Alaska Volcano Observatory for use in hazard statements and related cloud dispersion modeling. Base reflectivity images at four scan angles provided additional insight into the vertical ash distribution. Generally, the eruption column and associated volcanic clouds had the greatest areal coverage and highest reflectivity values (as high as +60 dBZ) at the two lowest scan elevation angles (0.5 and 1.5 degrees or heights of about 3.8 to 7.2 km above sea level). The explosions on January 13 and 17 produced volcanic clouds that propagated upwind for ten to twenty minutes before dispersing, suggesting that some of the ash was being generated by pyroclastic flows on the flanks. Drifting volcanic clouds were tracked in the data for as long as two hours after the start of the eruption, with reflectivity values as low as -4 dBZ observed. Retrospective analyses of level-3 NEXRAD data from the Kenai (PAHG) and King Salmon (PAKC) radars (200 km SW of Augustine) examined radial base velocity and spectrum width (a measure of the velocity variance within a scan volume) at four scan angles. The highest base velocities observed were for the January 17 event, which reached 33 m/s, the maximum value computed by the level-3 algorithm. This event, and similar ones on January 13, were characterized by moderately high spectrum widths (as large as 9.8 m/s), indicative of turbulence and wind shear.

Schneider, D. J.; Scott, C.; Wood, J.; Hall, T.

2006-12-01

120

Rates of oxidative weathering on the surface of Mars  

NASA Astrophysics Data System (ADS)

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, R. G.; Fisher, D. S.

1993-02-01

121

Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects  

Microsoft Academic Search

Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact

Lindsay P. Keller; Susan J. Wentworth; David S. McKay

1998-01-01

122

Monitoring Inland Ice Cover under All-weather Conditions with the Combined Use of Microwave and GOES-R Observations  

NASA Astrophysics Data System (ADS)

The cryosphere exists at all latitudes and in about one hundred countries. Not only does the cryosphere play a significant role in climate, but also it has profound socio-economic value, especially over inland water, including lakes and rivers, due to its role in water resources and its impact on transportation, fisheries, hunting, herding, and agriculture. A number of ice characterization algorithms have been improved and/or developed for the next generation Geostationary Operational Environmental Satellite (GOES-R) Advanced Baseline Imager (ABI), including ice identification, ice concentration, ice thickness and age, and ice motion. These products will play an important role in monitoring ice cover over inland water considering its high spatial, temporal, and spectral resolution. However, the effectiveness of such products is constrained by cloud cover. Lake ice products from microwave observations are less affected by clouds, but their quality is hindered by coarse spatial and temporal resolution as well as contamination by the land surface. Optimization of all-weather ice products from microwave observations, and ice products with higher spatial and temporal resolutions from GOES-R enables us to monitor the ice characteristics over the inland water surfaces, e.g., the Great Lakes, effectively in real time under all-weather conditions, and improves the products that are being developed for ABI. The combined used of both products provides accurate, timely information on ice characteristics over inland water surfaces to meet the needs of transportation and winter weather forecasting. An overview of the ice cover, concentration, and motion products for both GOES-R and microwave observation will be given, and case studies of combining both products for monitoring ice characteristics over inland water will be presented.

Liu, Y.; Key, J. R.; Wang, X.

2010-12-01

123

Weathering Animation  

NSDL National Science Digital Library

Weathering is the term that describes all the processes that break down rocks in the environment near the Earth's surface. This module will help you to understand two weathering processes: mechanical and chemical.

2002-01-01

124

Characterization of surface carbon films on weathered Japaneseroof tiles by soft x-ray spectroscopy  

SciTech Connect

The effects of weathering on carbon films deposited onJapanese smoked roof tileswere investigated by soft x-ray absorption andemission spectroscopy using synchrotron radiation. X-ray absorptionmeasurements revealed that weathering oxidizes the carbon films and thatpartial carboxy chemical bonding occurs. Incident angle-dependent x-rayabsorption spectra in the C K region confirmed that the degree of theorientation at the surface of the oxidized carbon films decreases withweathering. However, the take-off angle-dependent C K x-ray emissionspectra showed that the orientation of the layered carbon structure ismaintained in the bulk portion when weathered. Therefore, it is confirmedthat oxidation proceeds from the surface of the carbon films. Weatheringdegrades and oxidizes the surface carbon films, which causes the metallicsilver color to change to darker gray.

Muramatsu, Y.; Yamashita, M.; Motoyama, M.; Hirose, M.; Denlinger, J.D.; Gullikson, E.M.; Perera, R.C.

2004-07-15

125

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

126

Observation and Research on Strong Meteor Showers and Their Catastrophic Space Weather Events  

NASA Astrophysics Data System (ADS)

During the first international joint observation of the Leo strong meteor shower, multidisciplinary and multi-media synthetic observation of Leo and Draco strong meteor showers and their catastrophic space weather events were carried out. The comprehensive analysis of the observed and related data of the Leo, Perseus and Draco strong meteor showers obtained for near half a century (from 1957 to 2003) fully verifies that the non-sporadic periodic strong meteor shower may lead to catastrophic space weather events. Preliminary identification is made of the following: the mechanism of formation of strong meteor showers, the law of occurrence of the fbEs abnormal peak and serious safety hazards for astronavigation. Also discussed in this paper are the evolutionary process of cometary dust, the law of occurrence and loss of cosmic dust storm and the mechanism of maintaining cosmic dust in the mid-latitude Es layer.

Ma, Yue-Hua; He, You-Wen; Xu, Pin-Xin; Zhao, Hai-Bin

2008-04-01

127

Changes in the weathering of rock surfaces in different geomorphological environments: glacial, nival and coastal.  

NASA Astrophysics Data System (ADS)

The sclerometer or Schmidt Rock Test Hammer has been broadly applied in geomorphology to estimate the strength of different rock types and to measure the degree of rock weathering. It has been proved that for a rock type, the rebound values are lower in weathered than in fresh rock surfaces. This evidence suggests that if there is any factor that causes a gradual change in the weathering degree, it must be possible to identify a distinctive tendency with the sclerometer. There are two types of factors that can cause gradual changes in the weathering degree. First, those related with the time of exposure of a rock surface, which are the basis of works that attempt to use the sclerometer as a tool for relative chronology. Second, those related with the frequency or duration at which the weathering agents operate, which are the basis for the studies focused on the efficacy of weathering. In both cases it is essential to understand how the factors of weathering are spatially distributed in order to achieve a good sampling procedure. We applied the sclerometer in three different environments: rock coasts, glacially exposed surfaces and rock surfaces subjected to nival processes. The sclerometer was used in a receding glacier in Tierra de Fuego, Argentina, assuming that the rock surface must be more weathered as more time passed since the exposure. The hypothesis was confirmed by the negative correlation between rebound values and the distance to the glaciar front. In rocky coasts, it was proved by field and laboratory data that one of the main factors responsible for variations in rock strength is the degree of weathering by tidally-induced wetting and drying. We found negative correlations between rebound values and tidal elevation in very different coastal environments in the NW of Spain and in the Beagle Channel. We also found that the absence of this relationship may be caused by processes of mechanical erosion, but they also can respond to disequilibrium of the intertidal surfaces with tidal range. The research on nival processes was conducted in an ancient glacial cirque in the western mountains of Galicia (NW Spain). The hypothesis here was that weathering degree of rock surface is related with the abrasion produced when a late-lying snow cover slides in the spring. The frequency and extent to which abrasion and other erosional processes take place depends mainly on the thickness of the snow accumulated in a rock wall. Therefore, the rock surfaces are more weathered as frequency and intensity of abrasion decreases with the distance to the rock wall. The experience in three different types of environment suggests that when the sclerometer is used to measure the weathering degree, the sampling method arises as one of the most important factors. The distribution of the sampling points must respond to the characteristics of each area, which needs a previous understanding of the processes and factors responsible of the variations in the degree of weathering. Aknowledgements This work was supported by the research projects GL2004-3380/BOS (Ministerio de Educación y Ciencia) and PGIDIT06PXIB239226PR and PGDIT05PXIC21001PN (Xunta de Galicia). A. Feal Pérez is supported by the grant AP2006-03854

Feal-Pérez, A.; Blanco-Chao, R.; Pérez-Alberti, A.; López-Bedoya, J.; Valcárcel-Díaz, M.

2009-04-01

128

Laboratory simulations of space weathering and impact heating of planetary surfaces: the TEM studies.  

NASA Astrophysics Data System (ADS)

Space weathering (SW) is alteration of optical and physical properties of the surface layers of airless solar system bodies due to exogenic processes such as micrometeorite bombardment and interaction with solar wind plasma. Understanding the nature of physical/chemical alteration produced by the SW processes is crucial to derive reliable mineralogical information from remote sensing data. Although natural space weathered samples collected from the surface of the Moon are available for study, the SW of other targets in different environments may produce different effects. Therefore, laboratory simulation experiments on various analogue materials and detailed characterisation of the produced effects are important.

Rout, S. S.; Moroz, L. V.; Baither, D.; van der Bogert, C. H.; Bischoff, A.

2008-09-01

129

Uijongbu, Camp LaGuardia, Korea, Limited Surface Observations Climatic Summary (LISOCS).  

National Technical Information Service (NTIS)

This report is similar to a Revised Uniform Summary of Surface Weather Observations (RUSSWO) except the summary generated is from data observed at limited-duty observation sites. This summary is blocked based on the normal hours of observation and only th...

1983-01-01

130

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

131

Using Space Weathering Models to Match Observed Spectra to Predicted Spectra  

NASA Astrophysics Data System (ADS)

Materials exposed to space weathering have exhibited marked spectral changes which include both a darkening and "reddening" of the spectra. For many years, we have conducted research into the physics behind these phenomena. This research (in the wavelength region of 0.4-0.9 microns (um)) has been fruitful and has resulted in a graphics-interface based application which produces expected spectra of materials which closely match observations. In addition, we have also established a link between basic physics of the optical properties of submicroscopic particles and the resulting spectra, and have implemented the first phase of a library of statistical analysis techniques designed to aid in object and material classification of ground-based observations of space weathered materials. We are continuing to extend our research scope by increasing the wavelengths under consideration to include near-infrared (0.4 - 2.5 um). The research utilizes data fusion techniques to aid in linking the a priori information gained from basic physics to the observed phenomena and to aid in determining spectral features that are unique to a specific space weathering environment or material. The research team is also utilizing data fusion techniques coupled with an augmented graphical interface application which will allow development of a system of algorithms which will provide accurate prediction of (and accurate categorization of) space environmental spectral effects.

Guyote, M.; Abercromby, K. J.; Okada, J.

132

Electrical Resistivity and Induced Polarization as Tools for Mapping Near-Surface Weathered Hydrocarbon Bodies  

NASA Astrophysics Data System (ADS)

Induced polarization (IP) and electrical resistivity (ER) surveys were conducted at two legacy oil refinery sites in central Alberta during the fall of 2005 and summer of 2006. The first site had areas of near surface weathered hydrocarbons, and the second site had areas of saline soil and groundwater and areas of weathered hydrocarbons. The conductive saline environment of the second site posed significant challenges for the IP investigation. At the both sites, ER imaged weathered hydrocarbon bodies as resistive anomalies above background values. IP inversions yielded high values of chargeability at the boundaries of the resistive hydrocarbon bodies. At the second site, a resistivity high was associated with a change in subsurface lithology. Unlike the anomalies resulting from weathered hydrocarbons, there was no corresponding increase in chargeability associated with the high resistivity due to the lithology change. The results from these two surveys indicate that a combination of ER and IP is an effective tool for both mapping weathered hydrocarbons and in differentiating between resistivity increases associated with near surface hydrocarbons and resistivity increases due to subsurface lithology.

MacDonald, J.; Forte, S.; Bentley, L.

2006-12-01

133

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

134

Chemical weathering in Malay Peninsula and North Borneo: Clay mineralogy and element geochemistry of river surface sediments  

Microsoft Academic Search

Weathering products of silicate rocks are particularly useful for evaluating the continental chemical weathering on the Earth’s\\u000a surface and its mechanism. Clay mineralogy and major-element geochemistry of surface sediment samples collected in major rivers\\u000a of Malay Peninsula and North Borneo in the tropical Southeast Asian region are used to study the present chemical weathering\\u000a process and its controlling factors of

Hao Wang; ZhiFei Liu; Edlic Sathiamurthy; Christophe Colin; JianRu Li; YuLong Zhao

2011-01-01

135

Surface weathering of rapakivi granite outcrops – implications for natural stone exploration and quality evaluation  

Microsoft Academic Search

Implications of surface weathering of rapakivi granite outcrops for natural stone evaluation were studied in the Wiborg rapakivi granite batholith in southeastern Finland. The study was performed as field mapping, comprising the whole batholith and as detailed investigations on selected outcrops. The Wiborg batholith is composed of wiborgite, pyterlite, even-grained rapakivi granite, porphyritic rapakivi granite, porphyry aplite, and gabbro-anorthosite. Wiborgite

Paavo Härmä; Olavi Selonen

2008-01-01

136

The link between clay mineral weathering and the stabilization of Ni surface precipitates  

SciTech Connect

The formation of transition-metal surface precipitates may occur during sorption to clay minerals under ambient soil conditions. This process may lead to significant long-term stabilization of the metal within the soil profile. However, the rates and mechanisms controlling surface precipitate formation are poorly understood. The authors monitored changes in the reversibility of Ni sorbed to a clay mineral, pyrophyllite, in model batch experiments maintained at pH 7.5 for up to 1 year. The macroscopic sorption and dissolution study was complemented by a time-resolved characterization of the sorbed phase via spectroscopic and thermal methods. They found that nickel became increasingly resistant, over time, to extraction with EDTA. Initially, the sorbed phase consisted of a Ni-Al layered double hydroxide (LDH). With time, the anionic species in the interlayer space of the LDH changed from nitrate to silica polymers transforming the LDH gradually into a precursor Ni-Al phyllosilicate. The authors believe that this phase transformation is responsible for a substantial part of the observed increase in dissolution resistance. Thus, clay mineral weathering and the time-dependent release of Al and Si ions controlled Ni precipitate nucleation and transformation. The results suggest a potential pathway for long-term Ni stabilization in soil.

Ford, R.G.; Scheinost, A.C.; Scheckel, K.G.; Sparks, D.L. [Univ. of Delaware, Newark, DE (United States). Dept. of Plant and Soil Sciences

1999-09-15

137

Real-Time Detection of Small Surface Objects Using Weather Effects  

Microsoft Academic Search

\\u000a Small surface objects, usually containing important information, are difficult to be identified under realistic atmospheric\\u000a conditions because of weather degraded image features. This paper describes a novel algorithm to overcome the problem, using\\u000a depth-aware analysis. Because objects-participating local patches always contain low intensities in at least one color channel,\\u000a we detect suspicious small surface objects using the dark channel prior.

Baojun Qi; Tao Wu; Hangen He; Tingbo Hu

2010-01-01

138

Mars weather and predictability: Modeling and ensemble data assimilation of spacecraft observations  

NASA Astrophysics Data System (ADS)

Combining the perspectives of spacecraft observations and the GFDL Mars General Circulation Model (MGCM) in the framework of ensemble data assimilation leads to an improved understanding of the weather and climate of Mars and its atmospheric predictability. The bred vector (BV) technique elucidates regions and seasons of instability in the MGCM, and a kinetic energy budget reveals their physical origins. Instabilities prominent in the late autumn through early spring seasons of each hemisphere along the polar temperature front result from baroclinic conversions from BV potential to BV kinetic energy, whereas barotropic conversions dominate along the westerly jets aloft. Low level tropics and the northern hemisphere summer are relatively stable. The bred vectors are linked to forecast ensemble spread in data assimilation and help explain the growth of forecast errors. Thermal Emission Spectrometer (TES) temperature profiles are assimilated into the MGCM using the Local Ensemble Transform Kalman Filter (LETKF) for a 30-sol evaluation period during the northern hemisphere autumn. Short term (0.25 sol) forecasts compared to independent observations show reduced error (3--4 K global RMSE) and bias compared to a free running model. Several enhanced techniques result in further performance gains. Spatially-varying adaptive inflation and varying the dust distribution among ensemble members improve estimates of analysis uncertainty through the ensemble spread, and empirical bias correction using time mean analysis increments help account for model biases. With bias correction, we estimate a predictability horizon of about 5 sols during which temperature, wind, and surface pressure forecasts initialized from an assimilation analysis are superior to a free running model forecast. LETKF analyses, when compared with the UK reanalysis, show a superior correspondence to independent radio science temperature profiles. Traveling waves in both hemispheres share a correspondence in phase, and temperature differences between the analyses are generally less than 5 K. Assimilation of Mars Climate Sounder (MCS) temperature profiles reveals the importance of vertical distributions of dust and water ice aerosol in reducing model bias. A strategy for assimilation of TES and MCS aerosol products is outlined for future work.

Greybush, Steven J.

139

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.

140

A new weather generator based on spectral properties of surface air temperatures  

Microsoft Academic Search

We present a new weather generator, which simulates daily precipitation occurrence and daily maximum and minimum air temperature. Precipitation occurrence is simulated with a two-state, second-order Markov process, while maximum and minimum daily temperatures are simulated using spectral methods. Data generated at nine stations in the Southeastern USA are then compared to: (1) observed station data, and (2) data generated

J. T. Schoof; A. Arguez; J. Brolley; J. J. O’Brien

2005-01-01

141

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

142

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

143

Influence of targeted observations on short-term forecasts of high-impact weather events in the Mediterranean  

NASA Astrophysics Data System (ADS)

The influence of targeted observations on short-range forecasts is tested over two different periods of PREVIEW (2008) and MEDEX (2009) Data Targeting field campaigns for a set of Mediterranean high-impact weather events. As targeted observations we have used not only extra radiosondes, but also enhanced satellite data observed in Singular Vectors (SVs) based sensitive regions. Three parallel observing system experiments, based on the High Resolution Limited-Area Model (HIRLAM) data assimilation and forecast system, have been conducted. Forecasts of the three experiments have been assessed using both verifying analyses for upper air fields, and surface observations for several meteorological parameters. Furthermore, quantitative precipitation forecasts (QPF) have been objectively verified using the novel feature oriented Structure-Amplitude-Location (SAL) method. The results obtained show that targeted observations have a generally positive impact. When enhanced satellite data are assimilated, the overall forecast skill is doubled. However, a distinct behaviour is found between PREVIEW and MEDEX cases. While for MEDEX cases the improvement is slight, for PREVIEW cases it is significant. It is suggested that this is due to the location of the target areas and the spatial distribution of the composite observing system and to the different atmospheric predictability in these two periods.

Campins, J.; Navascués, B.; Santos, C.; Amo-Baladrón, A.

2013-06-01

144

New observational strategies for reconstructing the solar UV flux for space weather applications  

NASA Astrophysics Data System (ADS)

Many applications in space weather and in space situational awareness require continuous solar spectral irradiance measurements in the UV range. However the continuous monitoring of the solar UV irradiance is a difficult task. Present Si photodetectors exhibit serious limitations in performance and lifetime. Moreover filters suffer from a rapid degradation which limit the duty cycle of the mission. Here we give a theoretical view of one kind of degradation based on the formation of pinholes on the optical surfaces. We propose a solution which is expected to overcome, at least partially, these problems. We propose a new approach based on the idea that it is not necessary to measure the all spectrum but that a few bands suffice to retrieve all the other wavelengths. Then we propose a new instrumental concept with detectors using only wide band gap materials. Those new detectors select directly the desired spectral range without using upstream filters which are the main source of measurement degradation. Five channels are at least needed to retrieve the full UV spectrum with an accuracy as good as the actual spectrometers for space weather applications. We strongly believe that this work could be an asset to the definition of future instruments in the framework of the Space situational Awareness raised by the European Space Agency.

Cessateur, Gaël.; Lilensten, Jean; Dudok De Wit, Thierry; Kretzschmar, Matthieu; BenMoussa, Ali

2012-07-01

145

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

146

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

147

Earth surface erosion and weathering from the 10Be (meteoric)/9Be ratio  

NASA Astrophysics Data System (ADS)

The isotope ratio of the meteoric cosmogenic nuclide 10Be to the mineral-derived stable isotope 9Be discloses both the Earth surface denudation rate and its weathering intensity. We develop a set of steady state mass balance equations that describes this system from a soil column over the hillslope scale to an entire river basin. The prerequisites making this new approach possible are: (1) the 9Be concentration of parent rock (typically 2.5±0.5 ppm in granitic and clastic sedimentary lithologies) is known; (2) both Be isotopes equilibrate between the fluids decomposing rock and reactive solids formed during weathering; and (3) a critical spatial scale is exceeded at which the fluxes of both isotopes into and out of the weathering zone are at steady state over the time scale of weathering (typically ˜10 kyr). For these cases the isotope ratios can be determined in bulk sediment or soil, on leachates from the reactive (adsorbed and pedogenic mineral-bound) phase in sediment or soil, and even on the dissolved phase in river water. The 10Be/9Be ratio offers substantial advantages over the single-isotope system of meteoric 10Be. The latter system allows to directly determine erosion rates only in the case that 10Be is fully retentive in the weathering zone and that riverine sorting has not introduced grain size-dependent 10Be concentration gradients in sediments. We show the feasibility of the 10Be/9Be tracer approach at the river scale for sediment and water samples in the Amazon basin, where independent estimates of denudation rates from in situ-produced 10Be exist. We furthermore calculate meaningful denudation rates from a set of published 10Be/9Be ratios measured in the dissolved load of globally distributed rivers. We conclude that this isotope ratio can be used to reconstruct global paleo-denudation from sedimentary records.

von Blanckenburg, Friedhelm; Bouchez, Julien; Wittmann, Hella

2012-10-01

148

Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects  

NASA Astrophysics Data System (ADS)

Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact and reworking, implantation of solar wind and flare particles, radiation damage and chemical effects from solar particles and cosmic rays, interactions with the lunar atmosphere, and sputtering erosion and deposition. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Understanding these effects is critical in order to fully integrate the lunar sample collection with remotely sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, Galileo). Our objective is to determine the origin of space weathering effects in lunar soils through combined electron microscopy and microspectrophotometry techniques applied to individual soil particles from <20 pm size factions (dry-sieved) of mature lunar soils. It has been demonstrated that it is the finest size fraction (<25 pm) of lunar soils that dominates the optical properties of the bulk soils.

Keller, Lindsay P.; Wentworth, Susan J.; McKay, David S.

1998-01-01

149

Weather service upgrade too costly?  

NASA Astrophysics Data System (ADS)

America needs timely and accurate weather forecasting, said Ernest F. Hollings (D-S.C.), chairman of the Senate Committee on Commerce, Science, and Transportation on National Ocean Policy. Calling the existing warning and forecast system dangerously obsolete, Hollings said that new technology “should dramatically improve the accuracy and timeliness of weather predictions,” as we face the new challenge of bringing the National Weather Service into the 21st century. Hollings' committee heard testimony to consider the modernization of the NWS and pending legislation (S98, S916) on June 18.Major components of the Weather Service Modernization program, according to John A. Knauss, administrator of the National Oceanic and Atmospheric Administration, are the Next Generation Weather Radar (NEXRAD), a new generation of Geostationary Operational Environmental Satellites (GOES-NEXT), the Automated Surface Observing System (ASOS), and the Advanced Weather Interactive Processing System (AWIA). The best defense against severe weather—early warnings—is probably hampered by outdated equipment, he added.

Bush, Susan

150

Iron weathering products in a CO 2 + (H 2O or H 2O 2) atmosphere: Implications for weathering processes on the surface of Mars  

NASA Astrophysics Data System (ADS)

Various iron-bearing primary phases and rocks have been weathered experimentally to simulate possible present and past weathering processes occurring on Mars. We used magnetite, monoclinic and hexagonal pyrrhotites, and metallic iron as it is suggested that meteoritic input to the martian surface may account for an important source of reduced iron. The phases were weathered in two different atmospheres: one composed of CO 2 + H 2O, to model the present and primary martian atmosphere, and a CO 2 + H 2O + H 2O 2 atmosphere to simulate the effect of strong oxidizing agents. Experiments were conducted at room temperature and a pressure of 0.75 atm. Magnetite is the only stable phase in the experiments and is thus likely to be released on the surface of Mars from primary rocks during weathering processes. Siderite, elemental sulfur, ferrous sulfates and ferric (oxy)hydroxides (goethite and lepidocrocite) are the main products in a water-bearing atmosphere, depending on the substrate. In the peroxide atmosphere, weathering products are dominated by ferric sulfates and goethite. A kinetic model was then developed for iron weathering in a water atmosphere, using the shrinking core model (SCM). This model includes competition between chemical reaction and diffusion of reactants through porous layers of secondary products. The results indicate that for short time scales, the mechanism is dominated by a chemical reaction with second order kinetics ( k = 7.75 × 10 -5 g -1/h), whereas for longer time scales, the mechanism is diffusion-controlled (De A = 2.71 × 10 -10 m 2/h). The results indicate that a primary CO 2- and H 2O-rich atmosphere should favour sulfur, ferrous phases such as siderite or Fe 2+-sulfates, associated with ferric (oxy)hydroxides (goethite and lepidocrocite). Further evolution to more oxidizing conditions may have forced these precursors to evolve into ferric sulfates and goethite/hematite.

Chevrier, V.; Mathé, P.-E.; Rochette, P.; Grauby, O.; Bourrié, G.; Trolard, F.

2006-08-01

151

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.

Forde, Evan B.

2004-04-01

152

The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation  

SciTech Connect

The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation is studied through the use of the Simple Biosphere Model (SiB) and the Center for Ocean-Land-Atmosphere interactions (COLA) GCM. Tests for the SiB sensitivity to the conversion of the forest to other short vegetation or bare soil were performed at Amazonian and Great Plains sites, and a North Wales spruce forest site respectively. The results show that deforestation has a significant influence on the local surface energy budget and surface weather. The influence is especially prominent at the Amazon and Great Plains sites, and larger in summer than in other seasons. The influence on the partitioning of surface incoming radiative energy is generally constrained by the local atmospheric boundary condition. The sensitivity of the COLA GCM to changes in initial soil wetness (ISW) is determined by repeating three 10-day model integrations with the same initial and boundary conditions as the control runs except the values of ISW, which are revised at 69 model grid points covering much of the continental U.S. It is found that the relations between the changes in the 5-day mean forecast surface air temperature/surface specific humidity and the changes in ISW depend upon vegetation type and the values of ISW, and can be approximated by regression equations. These relations are also confirmed with independent data. With the ISW revised based on these regression equations the surface forecasts of the revised runs are consistently improved. The spatial scale of the ISW anomaly determines the degree and range of the influence. The influence of a small regional ISW change is mainly confined to the local region and to low atmospheric levels. The influence on surface fluxes is strong and persists for more than one month, but the effects on precipitation are relatively weak, changeable, and complex, particularly when an interactive cloud scheme is used.

Yang, R.

1992-01-01

153

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

154

Development of a surface-specific, anti-weathering stone preservative treatment  

SciTech Connect

We are testing an anti-weathering preservation strategy that is specific to limestone surfaces. The strategy involves the application of a mineral-specific, bifunctional, passivating/coupling agent that binds to both the limestone surface and to the consolidating inorganic polymer matrix. The sol-gel based reactions form composite materials with desirable conservation and anti-weathering properties. We present the results of our efforts, the highlights of which are: (1) scanning probe microscopy of moisture-free calcite crystals treated with the trisilanol form of silylalkylaminocarboxylate (SAAC), reveals porous agglomerates that offer no significant resistance to the mild leaching action of deionized water. When the crystals are further consolidated with a silica-based consolidant (A2**), no dissolution is seen although the positive role of the passivant molecule is not yet delineated. (2) Modulus of rupture tests on limestone cores treated with an aminoalkylsilane (AEAPS) and A2** showed a 25-35% increase in strength compared to the untreated samples. (3) Environmental scanning electron microscopy of treated limestone subjected to a concentrated acid attack showed degradation of the surface except in areas where thick layers of the consolidant were deposited.

Rao, S.M.; Brinkar, C.J. [Sandia National Lab., Albuquerque, NM (United States); Rao, S.M.; Ross, T.J. [Univ. of New Mexico, Albuquerque, NM (United States)] [and others

1997-04-01

155

Snow on the Ross Ice Shelf: comparison of reanalyses and observations from automatic weather stations  

NASA Astrophysics Data System (ADS)

Snow accumulation measurements from automatic weather stations (AWS) around the Ross Ice Shelf (RIS), Antarctica, are used to provide a new set of ground-based observations which are compared to precipitation from the ECMWF ERA-Interim and NCEP/NCAR Reanalysis-2 datasets. The high temporal resolution of the AWS snow accumulation measurements allow for an event-based comparison of reanalyses precipitation to the in situ observations. Snow accumulation records from nine AWS provide multiple years of accumulation data between 2008 and 2012 over a relatively large, homogeneous region of Antarctica, and also provide the basis for a statistical evaluation of accumulation and precipitation events. The complex effects of wind on snow accumulation (which can both limit and enhance accumulation) complicate the use of the accumulation measurements, but this analysis shows that they can provide a valuable source of ground-based observations for comparisons to modelled precipitation on synoptic timescales. The analysis shows that ERA-Interim reproduces more precipitation events than NCEP-2, and these events correspond to an average 8.2% more precipitation. Significant correlations between reanalyses and AWS event sizes are seen at several stations and show that ERA-Interim consistently produces larger precipitation events than NCEP-2.

Cohen, L.; Dean, S.

2013-09-01

156

Ultramicroscopic observations on morphological changes in hair during 25 years of weathering  

Microsoft Academic Search

Weathering or long-term burial may cause profound morphological and histological changes in hair, which may affect the results of forensic and archaeological investigations. We therefore used ultramicroscopic techniques to assay the changes in weathering hair shafts caused by burial for up to 25 years. We found that the middle portion of hair shafts from living individuals shows the expected histological

Byung Soo Chang; Wan Sung Hong; Eunju Lee; Sung Moon Yeo; In Seok Bang; Yoon Hee Chung; Do Sun Lim; Ga Hee Mun; Jaehyup Kim; Sang Ock Park; Dong Hoon Shin

2005-01-01

157

Sublimation on the Greenland ice sheet from automated weather station observations  

Microsoft Academic Search

Greenland Climate Network (GC-Net) surface meteorological observations are used to estimate net surface water vapor flux at ice sheet sites. Results from aerodynamic profile methods are compared with eddy correlation and evaporation pan measurements. Two profile method types are applied to hourly data sets spanning 1995.4 to 2000.4. One method type is shown to accurately gauge sublimation using two humidity

Jason E. Box; Konrad Steffen

2001-01-01

158

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. Students also identify weather events that are commonly reported in the news and discuss how weather affects lives.

Foundation, Wgbh E.

2009-07-21

159

Utilizing map pattern classification and surface weather typing to relate climate to the Air Quality Index in Cleveland, Ohio  

NASA Astrophysics Data System (ADS)

Employing both map pattern classification and weather typing, this study examines the role of climate in impacting air quality in Cleveland, Ohio from 1998 to 2007. This research creates a large-scale map pattern-classification of 500 mb geopotential heights that characterizes the broad scale flow of the atmosphere and the Spatial Synoptic Classification (SSC), which typifies the weather situation at the surface, where pollutants ultimately interact with the population. Surface weather types are found to have a greater impact on the Air Quality Index (AQI) than typical circulation patterns. Warm (cool) weather types and circulation patterns with a ridge (trough) consistently relate to poor (better) air quality in Cleveland. When weather types and circulation patterns are considered in tandem, these relationships are reinforced. Circulation patterns appear to have considerable influence on air quality in conjunction with moderate surface weather types, with impacts differing by the primary pollutant considered. Spike days of high AQIs (days with an AQI of at least 100) show similar results.

Lee, Cameron C.; Ballinger, Thomas J.; Domino, Natalia A.

2012-12-01

160

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.

161

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

162

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.

163

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

164

Terminal Doppler Weather Radar Observation of Atmospheric Flow over Complex Terrain during Tropical Cyclone Passages.  

NASA Astrophysics Data System (ADS)

A Terminal Doppler Weather Radar (TDWR) started operation in Hong Kong, China, in 1997 for monitoring wind shear associated with thunderstorms affecting the Hong Kong International Airport. The airport was built on land reclaimed from the sea and lies to the immediate north of the mountainous Lantau Island, which has hills rising to nearly 1000 m. Since 1997, the airport experienced a number of tropical cyclone passages, some bringing strong southerly winds across these hills. Under these conditions the TDWR captured interesting but complex flow patterns in the lower atmosphere. The TDWR Doppler velocity datasets reveal features not previously observed with conventional instruments. These include shear lines, reverse flow, small-scale vortices, streaks of low-speed flow set against a high-speed background, as well as gap-related downslope high-speed flow. Hovmöller diagrams constructed from the Doppler velocity data bring out in considerable detail periodic shedding of vortices and transient wind patterns in the wake of the hills.

Shun, C. M.; Lau, S. Y.; Lee, O. S. M.

2003-12-01

165

Carbon mineralization: insights from field observations, experiments and modeling of accelerated weathering in mine tailings (Invited)  

NASA Astrophysics Data System (ADS)

Carbon exchange through kinetically controlled mineral-microbe-fluid-gas reactions in mine waste occurs on a scale that can rival the generation of greenhouse gases in large industrial operations. Field observations from four Canadian and Australian mine sites demonstrate carbon mineralization by natural weathering of mine tailings at inactive mines and as a by-product of mineral processing and tailings deposition at active mines. Carbon is trapped within magnesium carbonate minerals. Rates of carbon exchange between geologic, industrial, and atmospheric reservoirs varies by several orders of magnitude and are influenced by local climate and tailings handling practices. Stable isotopic data and laboratory experiments of kinetically limited carbon dioxide exchange between air and aqueous solution indicate that the rate of carbon uptake may be limited by the rate of carbon supply to some mine sites, making them prime candidates for acceleration. Silicate mineral depletions in vertical profiles through mine tailings deposits are consistent with dissolution of serpentine and brucite as the primary source of magnesium for carbon mineralization. Geochemical reactive transport models suggest that the rates of mineral dissolution inferred from field data are consistent with laboratory-determined mineral dissolution rate laws. Incorporation of these rate laws into geochemical models for carbon sequestration during underground injection into ultramafic rocks provides estimates of the rates of carbon mineralization that are significant but remain untested.

Dipple, G. M.; Wilson, S. A.; Bea, S.; Mayer, K. U.; Power, I. M.; Barker, S. L.; Southam, G.

2010-12-01

166

Plateau Weather: A Synoptic Study of IAGO and ANARE Observations in East Antarctica.  

National Technical Information Service (NTIS)

Automatic weather stations (AWS) have been operated for a number of years by U.S. and French scientists cooperating in Project Interactions Atmosphere, Glace, Ocean (IAGO) and by the Australian National Antarctic Research Expeditions (ANARE). Six of these...

U. Radok G. Wendler

1992-01-01

167

Program to Improve Performance of AFGL (Air Force Geophysical Laboratory) Automated Present Weather Observing Sensors.  

National Technical Information Service (NTIS)

Under a prior Air Force (AFGL) program two prototype Automated Present Weather Sensors were developed. The present program supported hardware and software upgrades Sensors were developed. The present program supported hardware and software upgrades to tho...

D. F. Hansen W. K. Shubert D. R. Rohleder

1988-01-01

168

The composition and crystallinity of the near-surface regions of weathered alkali feldspars  

NASA Astrophysics Data System (ADS)

Our ability to identify thin non-stoichiometric and amorphous layers beneath mineral surfaces has been tested by undertaking X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) work on alkali feldspars from pH 1 dissolution experiments. The outcomes of this work were used to help interpret XPS and TEM results from alkali feldspars weathered for <10,000 years in soils overlying the Shap Granite (north-west England). The chemistry of effluent solutions indicates that silica-rich layers a few nanometers in thickness formed during the pH 1 experiments. These layers can be successfully identified by XPS and have lower Al/Si, Na/Si, K/Si and Ca/Si values than the outermost ˜9 nm of unweathered controls. Development of Al-Si non-stoichiometry is coupled with loss of crystal structure to produce amorphous layers that are identifiable by TEM where >˜2.5 nm thick, whereas the crystallinity of albite is retained despite leaching of Na to depths of tens to hundreds on nanometers. Integration of XPS data over the outermost 6-9 nm of naturally weathered Shap feldspars shows that they have stoichiometric Al/Si and K/Si ratios, which is consistent with findings of previous TEM work on the same material that they lack amorphous layers. There is some XPS evidence for loss of K from the outermost couple of nanometers of Shap orthoclase, and the possibility of leaching of Na from albite to greater depths cannot be excluded using the XPS or TEM results. This study demonstrates that the leached layer model, as formulated from laboratory experiments, is inapplicable to the weathering of alkali feldspars within acidic soils, which is an essentially stoichiometric reaction.

Lee, Martin R.; Hodson, Mark E.; Brown, David J.; MacKenzie, Maureen; Smith, Caroline L.

2008-10-01

169

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

170

eHeroes and Swiff: EC-Funded FP7 networks for modelling and observation of space weather events  

NASA Astrophysics Data System (ADS)

We report on two EC-FP7 funded projects: Swiff and eHeroes. Swiff (swiff.eu) is a modelling effort that aims at producing an integrated space weather modelling and forecasting network. We are unifying into a single approach fluid and kinetic models to track space weather events from their solar origin to their impact on the Earth environment, eHeores (eheroes.eu) is a observational and modelling effort that collects and processes data to produce new data services and new models to track and predict space weather. eHeores focuses on the impact of space weather on space exploration including the effects on spacecraft, on the exploration of the Moon and Mars. We will report on the results obtained in these projects highlighting their relevance to space weather and its impact on the Earth and on space exploration. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SWIFF (project n° 263340, www.swiff.eu).

Lapenta, Giovanni

2013-04-01

171

Forecasting near-surface weather conditions and precipitation in Alaska's Prince William Sound with the PWS-WRF modeling system  

NASA Astrophysics Data System (ADS)

In the summer of 2009, several scientific teams engaged in a field program in Prince William Sound (PWS), Alaska to test an end-to-end atmosphere/ocean prediction system specially designed for this region. The "Sound Predictions Field Experiment" (FE) was a test of the PWS-Observing System (PWS-OS) and the culmination of a five-year program to develop an observational and prediction system for the Sound. This manuscript reports on results of an 18-day high-resolution atmospheric forecasting field project using the Weather Research and Forecasting (WRF) model. Special attention was paid to surface meteorological properties and precipitation. Upon reviewing the results of the real-time forecasts, modifications were incorporated in the PWS-WRF modeling system in an effort to improve objective forecast skill. Changes were both geometric (model grid structure) and physical (different physics parameterizations). The weather during the summer-time FE was typical of the PWS in that it was characterized by a number of minor disturbances rotating around an anchored low, but with no major storms in the Gulf of Alaska. The basic PWS-WRF modeling system as implemented operationally for the FE performed well, especially considering the extremely complex terrain comprising the greater PWS region. Modifications to the initial PWS-WRF modeling system showed improvement in predicting surface variables, especially where the ambient flow interacted strongly with the terrain. Prediction of precipitation on an accumulated basis was more accurate than prediction on a day-to-day basis. The 18-day period was too short to provide reliable assessment and intercomparison of the quantitative precipitation forecasting (QPF) skill of the PWS-WRF model variants.

Olsson, Peter Q.; Volz, Karl P.; Liu, Haibo

172

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

173

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

174

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

NASA Astrophysics Data System (ADS)

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 larger impactors. Regolith and porosity formation by such impacts have major affects on surface properties. Surface-bound exospheres arise on bodies such as the Moon and Europa from space irradiation and impact effects, and these atmospheres in turn interact chemically with the surfaces. Ejection of surface materials by sputtering, impacts, or volcanism (Io, Enceladus) becomes a local source of plasma, neutral gas, and dust. Systems of bodies, e.g., asteroids, Galilean moons, and Kuiper Belt Objects, can exchange surface materials through the intervening space environments via such processes. Orbiting or landed spacecraft missions to space-weathered bodies must survive those environments, account for processes that may hide the intrinsic composition of those bodies below a patina of space-weathering products, and exploit space environment interactions (e.g., sputtering) for measurements of surface and sub-surface properties. For potentially habitable environments such as Europa and Enceladus, the harmful and helpful effects may impact the search for biosignatures and prebiotic materials. Key mission and instrumental objectives recommended for the next decade include (1) measurement of full elemental and key isotope composition, (2) assessment of composition and radiation aging correlations to surface geology and topography, including any protected refugia of organics, (3) comparative compositional analysis of system bodies as records of system origins and evolution, (4) development of advanced remote sensing and in-situ analysis instruments for such analyses, and (5) supporting laboratory analyses to characterize surface properties under realistic conditions involving space weathering processes. White Paper Lead: John Cooper.

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

2009-09-01

175

Meteorological evaluation of a weather-chemistry forecasting model using observations from the TEXAS AQS 2000 field experiment  

NASA Astrophysics Data System (ADS)

Meteorological forecasts for the period of 25-30 August 2000 from a coupled weather-chemistry model are evaluated both qualitatively and quantitatively using the observations from different instruments that were deployed in metropolitan Houston during the Texas Air-Quality Study 2000 field experiment. The qualitative comparison is carried out with respect to the meteorological processes associated with the influence of the large-scale flow on the sea breeze that are essential to the development of the surface ozone exceedances over Houston, while the quantitative comparison is focused on the errors and uncertainties of the forecasts. The qualitative comparison is performed with respect to a conceptual model for the influence of the large-scale flow on the sea breeze. The comparison shows that although the overall forecasted influence of the large-scale flow on the sea breeze compares qualitatively well to the observations, quantitative differences do exist between the forecasted and observed wind speed and direction, as well as with temperature and moisture. It is found that the forecasted low-level winds have a systematic easterly bias and the forecasted low-level temperature has a cold bias. The errors in the forecasted low-level moisture appear relatively small, but with a cold bias they lead to higher relative humidity in the forecast than in reality. There is great sensitivity of the model forecasted low-level winds to different initial conditions. The quantitative comparison also indicates that the model's effective horizontal resolution corresponding to 1.67-km grid spacing is actually about 10 km.

Bao, J.-W.; Michelson, S. A.; McKeen, S. A.; Grell, G. A.

2005-11-01

176

The impact of observation systems on medium-range weather forecasting in a global forecast system  

NASA Astrophysics Data System (ADS)

To investigate the impact of various types of data on medium-range forecasts, observing system experiments are performed using an assimilation algorithm based on the National Centers for Environmental Prediction (NCEP)/Department of Energy (DOE) reanalysis system. Data-denial experiments for radiosonde, satellite, aircraft, and sea surface observations, and selected data experiments for radiosonde and surface data, are conducted for the boreal summer of 1997 and the boreal winter of 1997/1998. The data assimilation system used in this study is remarkably dependent on radiosonde data, which provides information about the three-dimensional structure of the atmosphere. As expected, the impact of radiosonde observations on medium-range forecasts is strongly positive over the Northern Hemisphere and tropics, whereas the satellite system is most beneficial over the Southern Hemisphere. These results are also found in experiments simulating historical changes in observation systems. Over the tropics, assimilation without radiosonde observations generates unbalanced analyses resulting in unrealistic forecasts that must be corrected by the forecast model. Forecasts based on analysis from the observation data before the era of radiosonde observation are found to be less meaningful. In addition, the impacts on forecasts are closely related to the geographical distribution of observation data. The memory of observation data embedded in the analysis tends to persist throughout forecasts. However, cases exist where the effect of forecast error growth is more dominant than that of analysis error, e.g., over East Asia in summer, and where the deficiency in observations is supplemented or the imbalance in analysis is adjusted by the forecast model during the period of forecasts. Forecast error growth may be related to the synoptic correction performed by the data assimilation system. Over data-rich areas, analysis fields are corrected to a greater extent by the data assimilation system than are those over data-poor areas, which can cause the forecast model to produce more forecast errors in medium-range forecasts. It is found that even one month per season is sufficient for forecast skill verification in data impact experiments. Additionally, the use of upper-air observations is found to benefit areas that are downstream of observation data-rich areas.

Hwang, Seung-On; Hong, Song-You

2012-05-01

177

Observation of a monthly variation in global surface temperature data  

Microsoft Academic Search

An analysis of global surface temperature data is described. The data originates from the European Centre for Medium Range Weather Forecasting, and covers the period 1986-1991 with a spatial resolution of 1.125 degrees. A global average temperature, Tav, defined as the area weighted average of local temperatures, has been calculated for each day in this time period. In addition to

Clive H. Best

1994-01-01

178

Observation of a monthly variation in global surface temperature data  

Microsoft Academic Search

An analysis of global surface temperature data is described. The data originates from the European Centre for Medium Range Weather Forecasting, and covers the period 1986–1991 with a spatial resolution of 1.125 degrees. A global average temperature, Tav, defined as the area weighted average of local temperatures, has been calculated for each day in this time period. In addition to

Clive H. Best

1994-01-01

179

Observation of a monthly variation in global surface temperature data  

Microsoft Academic Search

An analysis of global surface temperature data is described. The data originates from the European Center for Medium Range Weather Forecasting (ECMWF), and covers the period 1986-1991 with a spatial resolution of 1.125 degrees. A global average temperature, Tav, defined as the area weighted average of local temperatures, has been calculated for each day in this time period. In addition

Clive H. Best

1994-01-01

180

Unisys Weather  

NSDL National Science Digital Library

The Unisys weather website offers a host of weather analyses and forecasts. In the Analyses link, visitors can find satellite images as well as surface, upper air, and radar images. Visitors can learn the intricacies of Unisys's many forecast models such as the Nested Grid Model (NGM), Aviation Model, and the Rapid Update Cycle (RUC) Model. Users can find archived hurricane data for the Atlantic, the Eastern Pacific, and the Western Pacific. The site also furnishes archived surface maps, infrared satellite images, upper air charts, and sea surface temperature (SST) plots.

181

Terminal Doppler Weather Radar Observation of Atmospheric Flow over Complex Terrain during Tropical Cyclone Passages  

Microsoft Academic Search

To facilitate warning of low-level wind shear associated with convective storms, a Terminal Doppler Weather Radar (TDWR) was installed about 12 km to the northeast of the Hong Kong International Airport (HKIA). The HKIA is located just off the northern shore of an island known as Lantau. The HKIA lies on the lee side of the complex terrain of Lantau

C. M. Shun; S. Y. Lau; O. S. M. Lee

2003-01-01

182

Terminal Doppler Weather Radar Observation of Atmospheric Flow over Complex Terrain during Tropical Cyclone Passages  

Microsoft Academic Search

A Terminal Doppler Weather Radar (TDWR) started operation in Hong Kong, China, in 1997 for monitoring wind shear associated with thunderstorms affecting the Hong Kong International Airport. The airport was built on land reclaimed from the sea and lies to the immediate north of the mountainous Lantau Island, which has hills rising to nearly 1000 m. Since 1997, the airport

C. M. Shun; S. Y. Lau; O. S. M. Lee

2003-01-01

183

Terminal Doppler Weather Radar (TDWR) observation of atmospheric flow over complex terrain during tropical cyclone passages  

Microsoft Academic Search

To facilitate warning of low-level wind shear associated with convective storms, a Terminal Doppler Weather Radar (TWDR) was installed about 12 km to the northeast of the Hong Kong International Airport (HKIA). The HKIA is located just off the northern shore of an island known as Lantau. The HKIA lies on the lee side of the complex terrain of Lantau

Chi M. Shun; Sharon S. Lau

2000-01-01

184

NEXRAD Weather Radar Observations of the 2006 Augustine Volcanic Eruption Clouds  

Microsoft Academic Search

The 2006 eruption of Augustine Volcano, Alaska provided an exceptional opportunity to detect and measure explosive volcanic events and to track drifting volcanic clouds using WRS-88D (NEXRAD) weather radar data. Radar data complemented the real-time seismic monitoring by providing rapid confirmation of ash generation and cloud height. The explosive phase of the eruption consisted of thirteen discrete Vulcanian explosions from

D. J. Schneider; C. Scott; J. Wood; T. Hall

2006-01-01

185

Architecture vision and technologies for post-NPOESS weather prediction system: two-way interactive observing and modeling: Part II. Use case scenario  

NASA Astrophysics Data System (ADS)

This is a companion paper to "Architecture Vision and Technologies for post-NPOESS Weather Prediction System: Two-way Interactive Observing and Modeling". Our recently completed two-year NASA-sponsored study on Advanced Weather Forecasting Technologies concluded that it may be possible in the future to significantly extend the skill range of model based weather forecasting via a direct real-time two-way feedback between computer forecast models and highly networked, intelligent observing systems (Sensor Webs). The study group developed a high-level Weather Architecture to describe the system (see the companion paper). This paper describes application of the proposed Weather Architecture to a particular weather scenario-the US east coast Blizzard of January 24 and 25, 2000. The objective of the scenario exercise was to help clarify thinking on the architecture functions in light of realistic, tractable (1 to 5 day) forecast situations, and infrastructure and technologies that might be reasonably projected for 2015.

Higgins, Glenn J.; Kalb, Michael W.; Mahoney, Robert L.; Lutz, Robert; Mauk, Robin Y.; Seablom, Michael; Talabac, Stephen J.

2005-01-01

186

A dynamical history of the inner Neptunian satellites, and, Martian weather: Viking observations and M.O. data assimilation techniques  

NASA Astrophysics Data System (ADS)

We examine a scenario involving the capture origin of Triton, and infer the dynamical history of the Neptune satellite system. Triton's postcapture orbit forced chaotic perturbations on the original inner satellites of Neptune, leading to their mutual collisions and self-destruction. Neptune's current inner satellite system reformed equatorially after Triton's orbital circularization. The 4.7 deg inclination of 1989N6 is probably due to a temporary inclination resonance. The 2:1 secondary resonance of the 1989N6-1989N3 12:10 resonance would eject 1989N6 at 4.7 deg matching the observations. We have established limits for Neptune's Q:12,000 is less than QN is less than 330,000. We examine a steady-state scheme for data assimilation in the context of a single, sun-synchronous, polar-orbiting satellite. The optimal (Wiener) gains are steady in time, and equivalent to those of a Kalman filter. The gains are computed by iteration using prior estimates to assimilate simulated observations of one model run ('Truth') into another run. The resulting prediction errors then form the next estimate of the gains. In model tests, the scheme works well even if only the mass field is observed. Although the scheme was developed for Mars Observer, it should be applicable to data retrieved from Earth atmosphere satellites, e.g., UARS. Spring and fall Viking IRTM T15 observations are used to estimate the Martian weather correlation length scale in the range 0.5-1 mbar. The results are important in providing a benchmark for validating Martian GCMs, determining the optimal placement of a network of landers, and guiding data assimilation efforts. Atmospheric temperature observations are used to compute an atmospheric mean state, which is subtracted from the observations to yield weather temperature residuals. These residuals are correlated with each other to determine the weather temperature correlation length scale (approximately 1500km) and the weather temperature variance (approximately 4 11K2). This work suggests that approximately 110 landers are needed to globally observe Mars' weather.

Banfield, Donald J.

1994-01-01

187

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

Microsoft Academic Search

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

Brett F. Sanders; Feleke Arega; Martha Sutula

2005-01-01

188

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

189

The ELDORA\\/ASTRAIA Airborne Doppler Weather Radar: High-Resolution Observations from TOGA COARE  

Microsoft Academic Search

The ELDORA\\/ASTRAIA (Electra Doppler Radar\\/Analyese Stereoscopic par Impulsions Aeroporte) airborne Doppler weather radar was recently placed in service by the National Center for Atmospheric Research and the Centre d'étude des Environnements Terrestre et Planetaires in France. After a multiyear development effort, the radar saw its first field tests in the TOGA COARE (Tropical Oceans-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment) field

Peter H. Hildebrand; Wen-Chau Lee; Craig A. Walther; Charles Frush; Mitchell Randall; Eric Loew; Richard Neitzel; Richard Parsons; Jacques Testud; François Baudin; Alain Lecornec

1996-01-01

190

Spatial Variability of the Depth of Weathered and Engineering Bedrock using Multichannel Analysis of Surface Wave Method  

NASA Astrophysics Data System (ADS)

In this paper an attempt has been made to evaluate the spatial variability of the depth of weathered and engineering bedrock in Bangalore, south India using Multichannel Analysis of Surface Wave (MASW) survey. One-dimensional MASW survey has been carried out at 58 locations and shear-wave velocities are measured. Using velocity profiles, the depth of weathered rock and engineering rock surface levels has been determined. Based on the literature, shear-wave velocity of 330 ± 30 m/s for weathered rock or soft rock and 760 ± 60 m/s for engineering rock or hard rock has been considered. Depths corresponding to these velocity ranges are evaluated with respect to ground contour levels and top surface levels have been mapped with an interpolation technique using natural neighborhood. The depth of weathered rock varies from 1 m to about 21 m. In 58 testing locations, only 42 locations reached the depths which have a shear-wave velocity of more than 760 ± 60 m/s. The depth of engineering rock is evaluated from these data and it varies from 1 m to about 50 m. Further, these rock depths have been compared with a subsurface profile obtained from a two-dimensional (2-D) MASW survey at 20 locations and a few selected available bore logs from the deep geotechnical boreholes.

Anbazhagan, P.; Sitharam, T. G.

2009-03-01

191

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.

Nielsen-Gammon, John

1996-09-01

192

Reshaping of sandstone surfaces by cryptoendolithic cyanobacteria: bioalkalization causes chemical weathering in arid landscapes  

Microsoft Academic Search

We report a novel weathering mechanism in South African sandstone formations, where cryptoendolithic cyanobacteria induce weathering by substrate alkalization during photosynthesis. As a result, the upper rock part is loosened and then eroded away by physical forces such as wind, water, trampling. This special type of 'exfoliation' is widely distributed and affects the geomorphology of whole sandstone mountain ranges and

B. Budel; B. Weber; M. Kuhl; H. Pfanz; D. Sultemeyer; D. Wessels

2004-01-01

193

Observation of surface dark photovoltaic solitons.  

PubMed

Surface dark solitons in photovoltaic nonlinear media are reported. Taking advantage of diffusion and photovoltaic nonlinearities we demonstrated the surface dark solitons and their behaviors near surface theoretically and experimentally in LiNbO? crystal. It is very interesting that surface dark soliton is just half of dark soliton in bulk. Another interesting thing is that transverse modulation instability can be perfectly suppressed by surface dark soliton in virtue of surface. In addition, surface waveguides were written successfully utilizing surface dark soliton. PMID:23482012

Yang, Xi; Chen, Weiqiang; Yao, Peng; Zhang, Tianhao; Tian, Jianguo; Xu, Jingjun

2013-02-25

194

Modelled and observed continental surface heat fluxes  

NASA Astrophysics Data System (ADS)

Heat fluxes in the continental subsurface were estimated from general circulation model (GCM) simulations of the climate of the last millennium and compared to those obtained from subsurface geothermal data. Since GCMs have bottom boundary conditions (BBCs) that are less than 10 m deep and thus may be thermodynamically restricted in the continental subsurface, we used an idealized land surface model (LSM) with a very deep BBC to estimate the potential for realistic subsurface heat storage in the absence of bottom boundary constraints. Results indicate that there is good agreement between observed fluxes and GCM simulated fluxes for the 1780-1980 period when the GCM simulated temperatures are coupled to the LMS with deep BBC. These results emphasize the importance of placing a deep BBC in GCM soil components for the proper simulation of the overall continental heat budget. In addition, the agreement between the LSM surface fluxes and the borehole temperature reconstructed fluxes lends additional support to the overall quality of the GCM (ECHO-G) paleoclimatic simulations. Simulations to 2100 show a divergence between the LSM simulated subsurface heat content and the heat gain in the ECHO-G soil model, with the placement of the BBCs surpassing the thermodynamical effect of the choice of emission scenario as the most important factor determining heat absorption in the simulated subsurface.

Beltrami, H.; MacDougall, A. H.; Gonzalez-Rouco, F. J.; Stevens, M. B.; Bourlon, E.

2009-12-01

195

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

196

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

197

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

198

Mechanism of feldspar weathering--II. Observations of feldspars from soils  

Microsoft Academic Search

Examination of the surface morphology (via scanning electron microscopy) and surface composition (via X-ray photoelectron spectroscopy) of sodic plagioclase and potash feldspar grains taken from four different soils, provides little or no evidence for the existence of a tightly adhering protective surface layer of altered composition on the feldspar surface. Grains, from which all adhering clay has been removed by

Robert A. Berner; George R. Holdren Jr.

1979-01-01

199

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.

200

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.

Burrows, Charles

201

Failure Behaviour of High Density Polyethylene with an Embrittled Surface Layer Due to Weathering.  

National Technical Information Service (NTIS)

Weathering often leads to brittle failure of otherwise ductile plastic products and hence may strongly reduce the service life of plastic products used or stored outdoors. Therefore, the ultimate objective of the research was to predict the mechanical fai...

J. C. M. de Bruijn

1992-01-01

202

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.

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

2012-01-01

203

Automated Weather Observing System (Awos) Data Acquisition System (Adas) Operational Test and Evaluation (OT/E) Integration and OT/E Operational Test Plan.  

National Technical Information Service (NTIS)

The attached document delineates the various plans associated with the preparation and conduct of Operational Test and Evaluation (OT&E) Integration and OT&E Operational testing of the Automated Weather Observing System (AWOS) Data Acquisition System (ADA...

J. Barab J. Stratton

1992-01-01

204

Automated Weather Observing System (AWOS) Data Acquisition System (ADAS) Operational Test and Evaluation (OT and E) Integration and OT and E Operational Test Plan.  

National Technical Information Service (NTIS)

The attached document delineates the various plans associated with the preparation and conduct of Operational Test and Evaluation (OT and E) Integration and OT and E Operational testing of the Automated Weather Observing System (AWOS) Data Acquisition Sys...

J. Barab J. Stratton

1992-01-01

205

Weather Forecasting  

NSDL National Science Digital Library

Weather Forecasting is one of several online guides produced by the Weather World 2010 project at the University of Illinois. These guides use multimedia technology and the dynamic capabilities of the web to incorporate text, colorful diagrams, animations, computer simulations, audio, and video to introduce topics and concepts in the atmospheric sciences. This module introduces forecast methods and the numerous factors one must consider when attempting to make an accurate forecast. Sections include forecasting methods for different scenarios, surface features affecting forecasting, forecasting temperatures for day and night, and factors for forecasting precipitation.

2010-01-01

206

A regression-based statistical correction of mesoscale simulations for near-surface wind speed using remotely sensed surface observations  

NASA Astrophysics Data System (ADS)

Wind speed is an important meteorological variable for various scientific communities. In this study, numerical mesoscale simulations were performed over the Republic of Korea in 2006, to produce wind information distributed homogeneously with space. Then, an attempt was made to statistically correct the simulated nearsurface wind speed using remotely sensed surface observations. The weak wind season (WWS, from May to October) and strong wind season (SWS, from November to April) were classified on the basis of the annual mean wind speed. Although the spatial features and monthly variation pattern of the near-surface wind speed were reasonably simulated in the Weather Research and Forecasting (WRF) model, the simulations overestimated the observed values. To correct the simulated wind speeds, a regression-based statistical algorithm with different constants and coefficients for WWS and SWS was developed using match-up datasets of wind observations and satellitederived variables (land surface temperature and normalized difference water index). The corrected wind speeds showed reasonable performance for both WWS and SWS with respect to observed values. The monthly variation in the corrected wind speeds over the Republic of Korea also matched better with observations throughout the year, within a monthly bias range of approximately ± 0.2 m s-1. The proposed algorithm using remotely sensed surface observations may be useful for correcting simulated near-surface wind speeds and improving the accuracy of wind assessments over the Republic of Korea.

Kim, Do-Yong; Kim, Jin-Young; Kim, Jae-Jin

2012-11-01

207

Heterogeneous distribution of nanophase aluminosilicate weathering products: Interpreting Martian weathering  

NASA Astrophysics Data System (ADS)

Nanocrystalline alteration products form in a range of soil and regolith weathering environments on Earth. In some weathering systems, poorly crystalline aluminosilicates such as allophane are distributed heterogeneously, as a function of depth in a vertical weathering profile or as a function of micro-environmental factors. Both of these factors can be important for understanding weathering processes on Earth and are particularly important to consider when interpreting allophane on Mars. Chemical and mineralogical measurements of Mars could be confounded by a vertical heterogeneity common to many weathering systems, because what is observed at the surface by spacecraft may not be representative of the complete weathering system. Appropriate caution should be taken to compare surface measurements of Mars to terrestrial weathering environments that examine soil columns. Also, nanocrystalline aluminosilicates are known to form coatings on regolith particles and rock fragments and can be compositionally distinct from weathering products formed in the greater regolith matrix. These types of coatings are particularly important to consider for interpreting remotely sensed spectral measurements because fragmented rocks, from sand to boulders, comprise much of the relatively dust-free surfaces of Mars. Due to their strong influence on spectral observations, coatings could be strongly detectable by thermal infrared spectroscopy relative to coexisting, weakly aggregated fine-grained weathering products, resulting in the oversampling of coatings. Consequently, detected nanocrystalline aluminosilicates phases may not represent the overall weathering system. As an example of these influences, we will consider the high-silica material(s) detected in Mars northern plains. Although there are several models for how this material formed, if it formed by in situ regolith weathering then the high-silica material was precipitated from dissolved regolith materials. Evidence for extensive cryoturbation in the northern plains indicates that subsurface materials have been brought to the surface, thus any vertical compositional heterogeneity resulting from weathering may have been subsequently homogenized. However, small-scale compositional heterogeneities could persist. Although high-silica material may coat particulates that comprise much of the surface, it may only represent only a micro-environment of the subsurface weathering. For example, although we suggest that the northern plains contain a silica-rich allophanic phase, weathering may also have produced more aluminous phases that are undetected in spectra because they do not form coatings. In addition, we will consider the possibility that Martian weathering produces poorly crystalline aluminosilicate phases that are structurally different from true allophane. We will report on the thermal infrared spectral difference between these phases. The details of Martian weathering processes that can be inferred from detection of allophane are limited by how well vertical and micro-environmental heterogeneities are understood and compensated for, for which input from the terrestrial weathering and soil science communities is essential.

Kraft, M. D.; Sharp, T. G.; Rampe, E. B.

2011-12-01

208

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

209

Space weather risk  

Microsoft Academic Search

The importance of space weather to society is in a continuous increase since we are more and more dependent on reliable spaceborne and ground-based technological systems. Physical processes involved in space weather constitute a complicated chain from the Sun to the Earth's surface, so the management of space weather risks requires expertise in many disciplines of science and technology. In

Risto Pirjola; Kirsti Kauristie; Hanna Lappalainen; Ari Viljanen; Antti Pulkkinen

2005-01-01

210

Enhancing model-based land surface temperature estimates using multiplatform microwave observations  

NASA Astrophysics Data System (ADS)

Land surface temperature plays an important role in surface processes and is a key input for physically based retrieval algorithms of soil moisture and evaporation. This study presents a framework for using independent estimates of land surface temperature from five microwave satellite sensors to improve the accuracy of land surface temperature output from a numerical weather prediction system in an off-line (postprocessing) analysis. First, structural differences in timing and amplitude of the temperature signal were addressed. Then, satellite observations were assimilated into an auto-regressive error model, formulated to estimate errors in the numerical weather prediction output. Errors in daily minimum and amplitude were treated separately. Results of this study provide new insights about potential added benefits of preprocessing and off-line assimilation of microwave remote sensing-based and model-based temperature retrievals. It is shown that the satellite observations may be used to reduce errors in surface temperature, particularly for day-time hours. Preprocessing is responsible for the bulk of this reduction in temperature error; data assimilation is shown to further reduce the random temperature error by a few tenths of a Kelvin, accounting for a 10% reduction in RMSE.

Holmes, Thomas R. H.; Crow, Wade T.; Tugrul Yilmaz, M.; Jackson, Thomas J.; Basara, Jeffrey B.

2013-01-01

211

Terminal Doppler Weather Radar (TDWR) observation of atmospheric flow over complex terrain during tropical cyclone passages  

NASA Astrophysics Data System (ADS)

To facilitate warning of low-level wind shear associated with convective storms, a Terminal Doppler Weather Radar (TWDR) was installed about 12 km to the northeast of the Hong Kong International Airport (HKIA). The HKIA is located just off the northern shore of an island known as Lantau. The HKIA lies on the lee side of the complex terrain of Lantau when winds come from the east through the southwest. With the commissioning of the TDWR in 1997, interesting high-resolution radar data were collected in strong southerly flows during tropical cyclone passages. These data sets reveal the complex low-level atmospheric flow in the vicinity of the HKIA, including streaks of low-speed flow, reverse flows, small-scale vortices and high-speed gap flows. Animation sequences of the radar images suggest existence of von Karman vortex streets and vortex shedding in the wake regions. These phenomena could induce strong shear regions which led to significant low-level wind shear for landing/departing aircraft. Analysis of on-board flight data for a wind shear event experienced by a landing aircraft in strong southeasterly flow revealed that terrain- induced features with horizontal scale less than 1 km brought significant air speed changes to the aircraft over a short duration of time.

Shun, Chi M.; Lau, Sharon S.

2000-12-01

212

Rapid Retrieval and Assimilation of Ground Based GPS-Met Observations at the NOAA Forecast Systems Laboratory: Impact on Weather Forecasts  

NASA Astrophysics Data System (ADS)

This year, 2003, marks the tenth anniversary of ground-based Global Positioning System meteorology. GPS-Met as we now know it started in 1992 with the definition of the essential techniques to retrieve integrated (total column) precipitable water vapor (IPW) from zenith-scaled neutral atmospheric signal delays (Bevis et al., 1992). It culminated with the GPS/Storm experiment in 1993, which demonstrated the ability to make IPW measurements with about the predicted accuracy under warm-weather conditions (Rocken et al., 1995). Since then, most of the major advances in GPS-Met data processing have been in the form of improved mapping functions (Niell, 1996), the estimation of GPS signal delays in an absolute (Duan et al., 1996) versus a relative sense (Rocken et al., 1993), and improved GPS satellite orbit accuracy with reduced latency (Fang et al., 1998). Experiments with other GPS-Met data processing techniques, such as the estimation of line-of-sight GPS signal delays using a double-difference to zero-difference technique described by Alber et al. (2000) and Braun et al. (2001) are noted, but lingering questions about the validity of this approach (Gutman, 2002), and not the potential value of a slant-path measurements per se, (as enumerated by MacDonald and Xie, 2001 or Ha et al., 2002) have thus far precluded its routine implementation at the National Oceanic and Atmospheric Administration Forecast Systems Laboratory (NOAA/FSL). Since 1994, NOAA/FSL has concentrated on evaluating the scientific and engineering bases of ground-based GPS-Met and assessing its utility for operational weather forecasting, climate monitoring, satellite calibration and validation, and improved differential GPS positioning and navigation. The term “rapid” in the title of this paper is defined as “available in time to be used for a specific application.” The requirement for high accuracy GPS-Met retrievals with lower latency is primarily driven by two factors: the trend toward shorter forecast cycles and higher spatial resolution in mesoscale numerical weather prediction (NWP) models, and the use by weather forecasters in subjective forecasting and/or model verification. GPS and ancillary surface meteorological observations, and improved satellite orbits, must be available on demand. Data processing hardware and techniques must provide GPS-Met retrievals in sufficient time to be assimilated into the current model cycle. Model data assimilation techniques must minimize the errors in estimating the initial state of a numerical forecast that come from spatial and temporal aliasing when interpolating discrete observations into an "analysis increment" field. While more GPS-Met retrievals can minimize horizontal aliasing, they can do little to minimize vertical aliasing that comes from assimilating any vertically integrated quantity (e.g. satellite radiances, zenith tropospheric signal delays, or GPS-IPW retrievals) into an NWP model. This is primarily because the forecast background error at a discrete vertical level must be estimated from the difference between observed and forecast integrated quantities. Absent the development of a new observing system or measurement technique, we must rely on improved data assimilation techniques, coupled with the more efficient use of complementary observing systems, to improve the three-dimensional description of moisture in the atmosphere. NOAA/FSL has conducted data denial experiments since 1998 to determine the statistical impact that GPS-IPW retrievals have on 3-hour moisture and precipitation forecasts in the central United States. Results from 5-years of experiments indicate more or less continuous improvement in forecast skill as the GPS-Met network expands. Improvements are observed in relative humidity forecast accuracy at all levels below 500 hPa, and all precipitation levels above “trace”. The impact steadily decreases with the length of the forecast; it is usually substantial from 0-3 hours, and negligible from 6-12 hours. The largest impacts usually occur during active weather

Gutman, S.

2003-04-01

213

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.

Park, Yellowstone N.

214

Tracking tropical cloud systems - Observations for the diagnosis of simulations by the Weather Research and Forecasting (WRF) Model  

SciTech Connect

To aid in improving model parameterizations of clouds and convection, we examine the capability of models, using explicit convection, to simulate the life cycle of tropical cloud systems in the vicinity of the ARM Tropical Western Pacific sites. The cloud life cycle is determined using a satellite cloud tracking algorithm (Boer and Ramanathan, 1997), and the statistics are compared to those of simulations using the Weather Research and Forecasting (WRF) Model. Using New York Blue, a Blue Gene/L supercomputer that is co-operated by Brookhaven and Stony Brook, simulations are run at a resolution comparable to the observations. Initial results suggest a computational paradox where, even though the size of the simulated systems are about half of that observed, their longevities are still similar. The explanation for this seeming incongruity will be explored.

Vogelmann, A.M.; Lin, W.; Cialella, A.; Luke, E.; Jensen, M.; Zhang, M.

2010-03-15

215

Space Weather  

NASA Astrophysics Data System (ADS)

This volume provides a comprehensive overview of our current observational knowledge, theoretical understanding, and numerical capability with regard to the phenomena known as space weather. Space weather refers to conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems, and can endanger human life or health. The rapid advance in these technologies has provided us with unprecedented capability and convenience, and we have come to rely on them more and more. Technology has reduced society's risk to many kinds of natural disasters, but through its own vulnerability, it has actually increased society's risk to space weather. Adverse conditions in the space environment can cause disruption of satellite operations, communications, navigation, and electric power distribution grids, leading to a variety of socioeconomic losses.

Song, Paul; Singer, Howard J.; Siscoe, George L.

216

Artificial weathering of Spanish granites subjected to salt crystallization tests: Surface roughness quantification  

Microsoft Academic Search

For hundreds of years, two types of granite (Zarzalejo and Alpedrete) from the Madrid region, Spain, have been extensively used as building stones. Fresh specimens of both stone types have been sampled from their respective quarries and subjected to sodium sulphate salt crystallization test (SCT). The resulting physical and chemical weathering patterns have been characterized by polarized light optical and

P. López-Arce; M. J. Varas-Muriel; B. Fernández-Revuelta; M. Álvarez de Buergo; R. Fort; C. Pérez-Soba

2010-01-01

217

Observations on "Nonradiating surface sources": comment  

NASA Astrophysics Data System (ADS)

The proof, established in a recent paper [A. J. Devaney, "Nonradiating surface sources," J. Opt. Soc. Am. A21, 2216 (2004)], of the existence of nonradiating surface sources formed by singlet-plus-doublet components whose generated fields vanish in either of the regions separated by a closed or infinite surface where the source resides is corroborated by means of an equivalent but slightly different formalism based on treatment of partial differential operators in a weak derivative or distributional sense. This approach yields a construction procedure applicable to a broad class of singular nonradiating sources. A fundamental question raised in that paper concerning the nonexistence of nontrivial nonradiating infinite planar sources that generate vanishing fields at both associated half-spaces is re-examined, with the conclusion that it is actually possible to mathematically construct such singular nonradiating sources as long as one allows for higher-order singularities such as certain combinations of singlet and triplet components.

Marengo, Edwin A.

2006-01-01

218

Observations on "nonradiating surface sources": comment.  

PubMed

The proof, established in a recent paper [A. J. Devaney, "Nonradiating surface sources," J. Opt. Soc. Am. A 21, 2216 (2004)], of the existence of nonradiating surface sources formed by singlet-plus-doublet components whose generated fields vanish in either of the regions separated by a closed or infinite surface where the source resides is corroborated by means of an equivalent but slightly different formalism based on treatment of partial differential operators in a weak derivative or distributional sense. This approach yields a construction procedure applicable to a broad class of singular nonradiating sources. A fundamental question raised in that paper concerning the nonexistence of nontrivial nonradiating infinite planar sources that generate vanishing fields at both associated half-spaces is re-examined, with the conclusion that it is actually possible to mathematically construct such singular nonradiating sources as long as one allows for higher-order singularities such as certain combinations of singlet and triplet components. PMID:16478070

Marengo, Edwin A

2006-01-01

219

A sub-regional climate cluster analysis over Italy from regional climate model simulation and weather station observations  

NASA Astrophysics Data System (ADS)

High resolution Regional Climate Models (RCMs) are a key tools in producing downscaled and calibrated outputs for impact studies where local scale climate information are needed. Recent studies suggest that in the processing chain that goes from the global scale climate projection to the local scale information, the use of an intermediate scale RCM increases the quality of the climate information produced at the local scale. We propose a direct assessment of the type of improvements achieved by using RCMs for producing the intermediate scale climate information required for example in impact studies. We use relatively long (50 years) daily climate records of 64 weather stations in Italy the evaluate how the ENEA-PROTHEUS system reconstruct the sub-regional climate clusters emerging from observation at a spatial scale finer than the one of the global driver. Specifically, on one side we tested the capability of ENEA-PROTHEUS regional coupled model, run in a 'perfect boundaries' mode using ERA-40, to capture the pattern of sub-regional climate spatial clusters relative to maximum/minimum temperature and rainfall. On the other hand, we considered the spatial averages of these parameters on the sub-regional climate spatial clusters. We compare the model output and the weather station data in terms of their representation of the mean seasonal cycle, the corresponding interannual variability and large deviations. We find a close agreement between model and observations. In particular, although biases in the modelled seasonal cycle are present, the model is able to reproduce the frequency and the seasonality of intense events for all seasons, including hot and cold spells and intense rainfalls, especially for alpine regions.

Calmanti, Sandro; Maimone, Filippo; Dell'Aquila, Alessandro; Ciciulla, Fabrizio

2013-04-01

220

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

221

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

222

Venus NIR Surface Emissivity estimated from VIRTIS on Venus Express Observations  

NASA Astrophysics Data System (ADS)

Spectral window regions close to 1?m allow for the transfer of thermal radiation from the surface through the atmosphere of Venus. Results of radiative transfer modeling are used to invert VIRTIS images at 1.02, 1.10 and 1.18?m for thermal emission of the surface. Local atmospheric transmittance is derived from the VIRTIS band at 1.31?m. Several hundreds of VIRTIS images covering in total most of the southern hemisphere of Venus have thus been analyzed and stacked for improvement of signal to noise ratio. The results of this approach are to some extent ambiguous since neither surface emissivity nor surface temperature are well known. Furthermore aerosols or a gradient of absorbing gaseous constituents near the surface might affect the interpretation. But neglecting any effects of the near surface atmosphere and assuming parameters of the radiative transfer model within reasonable ranges it is possible to estimate either surface emissivity or surface temperature. Temperature of surface and atmosphere is mostly a function of altitude, no large diurnal, seasonal or latitudinal variations are expected in the lower atmosphere. The lapse rate is constrained by the adiabatic lapse rate. A hint for global average of surface emissivity is given by the dominance of probably basaltic volcanic plains on the southern hemisphere. It is however imaginable that temperature dependant weathering leads to a trend of emissivity with altitude similar to that seen in the Magellan radiothermal emissivity observations. Regardless of any global variations of lapse rate or emissivity with altitude, spatial variations of emissivity independent from topography can be examined by assuming constant emissivity and fitting surface temperature accordingly to the global relation of thermal emission to topography. This spatial variation of thermal emission is assumed to be due to variation of surface emissivity and shows correlation with some geological features known from Magellan radar images. In the Lada Terra region large lava streams, Cavillaca - and Juturna Fluctus, show increased emissivity with respect to neighboring regions of the same altitude. Other large lava streams in the region show a similar but less obvious relative emissivity. Large areas of tessera terrain on the contrary consistently show relative low emissivity. While this variation of emissivity might be related to content of mafic minerals it is also conceivable that weathering and thus age of the terrain in question is responsible. The accumulation of observations by VIRTIS during the Venus Express mission will allow us to study with a larger database these correlations and to further disentangle possible atmospheric from surface contributions and thus to increase understanding of surface composition as well as of composition and temperature of the atmosphere in contact with the surface.

Mueller, N.; Helbert, J.; Hashimoto, G.; Kostama, P.; Marinangeli, L.; Erard, S.; Piccioni, G.; Drossart, P.; Venus Express Team

2007-12-01

223

An assessment of surface soil temperature products from numerical weather prediction models using ground-based measurements  

NASA Astrophysics Data System (ADS)

Surface soil temperature estimates at approximately 0.05 m depth are needed to retrieve soil moisture from the planned Soil Moisture Active Passive (SMAP) L-band (1.4 GHz) satellite. Numerical weather prediction (NWP) systems as operated by various weather centers produce global estimates of soil temperature. In this study in situ data collected over the state of Oklahoma are used to assess surface (soil) temperature from three NWP systems: (1) the integrated forecast system from the European Center for Medium range Weather Forecasts (ECMWF), (2) the modern-era retrospective analysis for research and applications (MERRA) from the NASA Global Modeling and Assimilation Office, and (3) the global data assimilation system used by the National Center for Environmental Prediction (NCEP). The results are presented by hour of day with specific attention directed to the SMAP early morning overpass time at around 6 A.M. local time, and the period of 1 April to 1 October 2009. It was found that the NWP systems estimate the 0.05 m soil temperature at this time of day with an overall root mean square error of 1.9 to 2.0 K. It is shown that this error can be reduced to 1.6 to 1.8 K when differences between the modeling and measurement depth are accounted for by synchronizing each NWP set to match the mean phase of the in situ data and adjusting the amplitude in accordance with heat flow principles. These results indicate that with little calibration all products meet the SMAP error budget criteria over Oklahoma.

Holmes, Thomas R. H.; Jackson, Thomas J.; Reichle, Rolf H.; Basara, Jeffrey B.

2012-02-01

224

In situ observations from STEREO/PLASTIC: a test for L5 space weather monitors  

NASA Astrophysics Data System (ADS)

Stream interaction regions (SIRs) that corotate with the Sun (corotating interaction regions, or CIRs) are known to cause recurrent geomagnetic storms. The Earth's L5 Lagrange point, separated from the Earth by 60 degrees in heliographic longitude, is a logical location for a solar wind monitor - nearly all SIRs/CIRs will be observed at L5 several days prior to their arrival at Earth. Because the Sun's heliographic equator is tilted about 7 degrees with respect to the ecliptic plane, the separation in heliographic latitude between L5 and Earth can be more than 5 degrees. In July 2008, during the period of minimal solar activity at the end of solar cycle 23, the two STEREO observatories were separated by about 60 degrees in longitude and more than 4 degrees in heliographic latitude. This time period affords a timely test for the practical application of a solar wind monitor at L5. We compare in situ observations from PLASTIC/AHEAD and PLASTIC/BEHIND, and report on how well the BEHIND data can be used as a forecasting tool for in situ conditions at the AHEAD spacecraft with the assumptions of ideal corotation and minimal source evolution. Preliminary results show the bulk proton parameters (density and bulk speed) are not in quantitative agreement from one observatory to the next, but the qualitative profiles are similar.

Simunac, K. D. C.; Kistler, L. M.; Galvin, A. B.; Popecki, M. A.; Farrugia, C. J.

2009-10-01

225

Modeling convective-stratiform precipitation processes on a Mei-Yu front with the Weather Research and Forecasting model: Comparison with observations and sensitivity to cloud microphysics parameterizations  

NASA Astrophysics Data System (ADS)

Deep convective-scale simulations of the linear mesoscale convective systems (MCSs) formed on a Mei-Yu front over the Huai River basin in China on 7-8 July 2007 were conducted using the Advanced Research Weather Research and Forecasting model to investigate impacts of cloud microphysics parameterizations on simulated convective-stratiform precipitation processes. Eight simulations were performed with identical configurations, except for differences in the cloud microphysics parameterizations. Measurements from rain gauges, ground-based weather radars, and the Tropical Rainfall Measuring Mission satellite Precipitation Radar were used to quantitatively evaluate the model results. While all of the simulations largely capture the observed large-scale characteristics of the precipitation event, notable differences among the simulations are found in the morphology and evolution of the MCSs at mesoscale and cloud scale. Significant influences on the coupling between dynamical and microphysical processes at the resolved deep convective scale by the various microphysical parameterizations are evident. On the one hand, the different microphysical schemes produce not only substantial differences in intensity of convective precipitation but also distinguishable vertical distributions of latent heating and condensate loading in the deep convective regions, which in turn results in significant differences in the vertical distributions of vertical air velocity and in the heights and strength of detrainment from deep convective regions. Consequently, detrainment of hydrometeors and positively buoyant air from the deep convective regions to the stratiform regions is significantly different, which impacts the formation and growth of ice-phase hydrometeors at the upper levels and thus surface rainfall rates in the stratiform regions. On the other hand, prediction of rain size distribution significantly impacts the simulated rain evaporation rates and mass-weighted rain fall speeds, and hence rain flux. Improper determination of the intercept parameter of rain size distribution can result in unrealistic features in the morphology of the storm and can have substantial impacts on precipitation distribution and evolution.

Luo, Yali; Wang, Yanjie; Wang, Hongyan; Zheng, Yongjun; Morrison, Hugh

2010-09-01

226

Impacts of weather conditions modified by urban expansion on surface ozone: Comparison between the Pearl River Delta and Yangtze River Delta regions  

Microsoft Academic Search

In this paper, the online weather research and forecasting and chemistry (WRF-Chem) model is used to explore the impacts of\\u000a urban expansion on regional weather conditions and its implication on surface ozone concentrations over the Pearl River Delta(PRD)\\u000a and Yangtze River Delta(YRD) regions. Two scenarios of urban maps are used in the WRF-Chem to represent the early 1990s (pre-urbanization)\\u000a and

Xuemei Wang; Fei Chen; Zhiyong Wu; Meigen Zhang; Mukul Tewari; Alex Guenther; Christine Wiedinmyer

2009-01-01

227

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

228

Observed Near-Surface Currents Under High Wind Speeds.  

National Technical Information Service (NTIS)

From the Surface Velocity Program (SVP) drifter current and QuikSCAT wind data, the relationship between the observed near-surface current vectors and surface wind vectors for the northwestern Pacific Ocean under high winds (20 50 m s expn -1) are obtaine...

G. Chen L. R. Centurioni P. C. Chu R. Tseng Y. Chang

2012-01-01

229

Plasmon Surface Polariton Dispersion by Direct Optical Observation.  

ERIC Educational Resources Information Center

|Describes several simple experiments that can be used to observe directly the dispersion curve of plasmon surface polaritons (PSP) on flat metal surfaces. A method is described of observing the increonental change in the wave vector of the PSP due to coatings that differ in thickness by a few nanometers. (Author/CS)|

Swalen, J. D.; And Others

1980-01-01

230

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

231

Studying the Space Weather Features of the High-Latitude Ionosphere by Using a Physics-Based Data Assimilation Model and Observational Data from Ground Magnetometer Arrays  

NASA Astrophysics Data System (ADS)

The high-latitude ionosphere is a very dynamic region in the solar-terrestrial environment. Frequent disturbances in the region can adversely affect numerous military and civilian technologies. Accurate specifications and forecasts of the high-latitude electrodynamic and plasma structures have fundamental space weather importance for enabling mitigation of adverse effects. Presently, most of the space-weather models use limited observations and/or indices to define a set of empirical drivers for physical models to move forward in time. Since the empirical drivers have a "climatological" nature and there are significant physical inconsistencies among various empirical drivers due to independent statistical analysis of different observational data, the specifications of high-latitude space environment from these space weather models cannot truthfully reflect the weather features. In fact, unrealistic small- and large-scale structures could be produced in the specifications and forecasts from these models. We developed a data assimilation model for the high-latitude ionospheric plasma dynamics and electrodynamics to overcome these hurdles. With a set of physical models and an ensemble Kalman filter, the data assimilation model can determine the self-consistent structures of the high-latitude convection electric field, ionospheric conductivity, and the key drivers associated with these quantities by ingesting data from multiple observations. These ingested data include the magnetic perturbation from the ground-based magnetometers in the high-latitude regions, magnetic measurements of IRIDIUM satellites, SuperDARN line-of-sight velocity, and in-situ drift velocity measured by DMSP satellites. As a result, the assimilation model can capture the small- and large-scale plasma structures and sharp electrodynamic boundaries, thus, can provide a more accurate picture of the high-latitude space weather. In this presentation, we will first briefly describe the data-assimilation model of high-latitude electrodynamics and its strengths over the other space-weather models. Then we will present the space weather features produced by the model for quiet and storm periods constrained by the data from ground magnetometer arrays. This will demonstrate the dynamic variability of the high-latitude ionosphere. Finally, we will present high-resolution ionospheric modeling results of the time-evolution and spatial features of the high-latitude plasma structures to further demonstrate the model's capability in producing the space weather features in the high-latitude ionosphere. These results will illuminate the importance of real-time data availability and data assimilation models for accurate specification and forecasting of space weather.

Zhu, L.; Schunk, R. W.; Scherliess, L.; Sojka, J. J.; Eccles, J. V.

2011-12-01

232

Initializing numerical weather prediction models with satellite-derived surface soil moisture: Data assimilation experiments with ECMWF's Integrated Forecast System and the TMI soil moisture data set  

Microsoft Academic Search

Satellite-derived surface soil moisture data sets are readily available and have been used successfully in hydrological applications. In many operational numerical weather prediction systems the initial soil moisture conditions are analyzed from the modeled background and 2 m temperature and relative humidity. This approach has proven its efficiency to improve surface latent and sensible heat fluxes and consequently the forecast

M. Drusch

2007-01-01

233

Distribution of major elements in Atlantic surface sediments (36°N-49°S): Imprint of terrigenous input and continental weathering  

NASA Astrophysics Data System (ADS)

Numerous studies use major element concentrations measured on continental margin sediments to reconstruct terrestrial climate variations. The choice and interpretation of climate proxies however differ from site to site. Here we map the concentrations of major elements (Ca, Fe, Al, Si, Ti, K) in Atlantic surface sediments (36°N-49°S) to assess the factors influencing the geochemistry of Atlantic hemipelagic sediments and the potential of elemental ratios to reconstruct different terrestrial climate regimes. High concentrations of terrigenous elements and low Ca concentrations along the African and South American margins reflect the dominance of terrigenous input in these regions. Single element concentrations and elemental ratios including Ca (e.g., Fe/Ca) are too sensitive to dilution effects (enhanced biological productivity, carbonate dissolution) to allow reliable reconstructions of terrestrial climate. Other elemental ratios reflect the composition of terrigenous material and mirror the climatic conditions within the continental catchment areas. The Atlantic distribution of Ti/Al supports its use as a proxy for eolian versus fluvial input in regions of dust deposition that are not affected by the input of mafic rock material. The spatial distributions of Al/Si and Fe/K reflect the relative input of intensively weathered material from humid regions versus slightly weathered particles from drier areas. High biogenic opal input however influences the Al/Si ratio. Fe/K is sensitive to the input of mafic material and the topography of Andean river drainage basins. Both ratios are suitable to reconstruct African and South American climatic zones characterized by different intensities of chemical weathering in well-understood environmental settings.

Govin, Aline; Holzwarth, Ulrike; Heslop, David; Ford Keeling, Lara; Zabel, Matthias; Mulitza, Stefan; Collins, James A.; Chiessi, Cristiano M.

2012-01-01

234

Observed near-surface currents under high wind speeds  

NASA Astrophysics Data System (ADS)

From the Surface Velocity Program (SVP) drifter current and QuikSCAT wind data, the relationship between the observed near-surface current vectors and surface wind vectors for the northwestern Pacific Ocean under high winds (20-50 m s-1) are obtained with quantitative estimations of near-surface drift ratio (current speed versus wind speed)r(˜2%) and near-surface drift angle? (˜0°-10° to the right of the winds). These estimations keep unchanged after removing the surface geostrophic component. From the SVP drifter current and daily WindSat wind data, the estimated ris still approximately 2%. Three linear regression equations are obtained between the observed near-surface current speeds and the surface wind stress for the high wind range.

Chang, Y.-C.; Chen, G.-Y.; Tseng, R.-S.; Centurioni, L. R.; Chu, Peter C.

2012-11-01

235

The impact of land surface temperature on soil moisture anomaly detection from passive microwave observations  

NASA Astrophysics Data System (ADS)

For several years passive microwave observations have been used to retrieve soil moisture from the Earth's surface. Low frequency observations have the most sensitivity to soil moisture, therefore the current Soil Moisture and Ocean Salinity (SMOS) and future Soil Moisture Active and Passive (SMAP) satellite missions observe the Earth's surface in the L-band frequency. In the past, several satellite sensors such as the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and WindSat have been used to retrieve surface soil moisture using multi-channel observations obtained at higher microwave frequencies. While AMSR-E and WindSat lack an L-band channel, they are able to leverage multi-channel microwave observations to estimate additional land surface parameters. In particular, the availability of Ka-band observations allows AMSR-E and WindSat to obtain coincident surface temperature estimates required for the retrieval of surface soil moisture. In contrast, SMOS and SMAP carry only a single frequency radiometer and therefore lack an instrument suited to estimate the physical temperature of the Earth. Instead, soil moisture algorithms from these new generation satellites rely on ancillary sources of surface temperature (e.g. re-analysis or near real time data from weather prediction centres). A consequence of relying on such ancillary data is the need for temporal and spatial interpolation, which may introduce uncertainties. Here, two newly-developed, large-scale soil moisture evaluation techniques, the triple collocation (TC) approach and the Rvalue data assimilation approach, are applied to quantify the global-scale impact of replacing Ka-band based surface temperature retrievals with Modern Era Retrospective-analysis for Research and Applications (MERRA) surface temperature output on the accuracy of WindSat and AMSR-E based surface soil moisture retrievals. Results demonstrate that under sparsely vegetated conditions, the use of MERRA land surface temperature instead of Ka-band radiometric land surface temperature leads to a relative decrease in skill (on average 9.7%) of soil moisture anomaly estimates. However the situation is reversed for highly vegetated conditions where soil moisture anomaly estimates show a relative increase in skill (on average 13.7%) when using MERRA land surface temperature. In addition, a pre-processing technique to shift phase of the modelled surface temperature is shown to generally enhance the value of MERRA surface temperature estimates for soil moisture retrieval. Finally, a very high correlation (R2 = 0.95) and consistency between the two evaluation techniques lends further credibility to the obtained results.

Parinussa, R. M.; Holmes, T. R. H.; Yilmaz, M. T.; Crow, W. T.

2011-10-01

236

NOAA Daily Weather Maps  

NSDL National Science Digital Library

The charts on this website are the principal charts of the former Weather Bureau publication, "Daily Weather Map." They are the Surface Weather Map, the 500-Millibar Height Contours chart, the Highest and Lowest Temperatures chart, and the Precipitation Areas and Amounts chart. For each day, simple charts are arranged on a single page. These charts are the surface analysis of pressure and fronts, color shading, in ten degree intervals,of maximum and minimum temperature, 500-Millibar height contours, and color shaded 24-hour total precipitation. These charts act as links to their respective Daily Weather Map charts. All charts are derived from the operational weather maps prepared at the National Centers for Environmental Prediction, Hydrometeorological Prediction Center, National Weather Service.

Center, Hydrometeorological P.

2011-01-01

237

Comparisons of Surface Meteorology and Turbulent Heat Fluxes over the Atlantic: NWP Model Analyses versus Moored Buoy Observations  

Microsoft Academic Search

Surface meteorological variables and turbulent heat fluxes in the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalyses 1 and 2 (NCEP1 and NCEP2) and the analysis from the operational system of the European Centre for Medium-Range Weather Forecasts (ECMWF) are compared with high-quality moored buoy observations in regions of the Atlantic including the eastern North Atlantic, the coastal

Bomin Sun; Lisan Yu; Robert A. Weller

2003-01-01

238

Plymouth State Weather Center  

NSDL National Science Digital Library

The Plymouth State Weather Center offers the latest observations and forecasts for the United States and Southern Canada. By simply selecting a state, individuals can find data on the temperature, wind direction and speed, cloud cover, and other weather information for stations throughout the selected region. The website provides a state forecast as well. The map on the homepage allows users to observe the overall weather patterns throughout the continental United States and Southern Canada.

239

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

240

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

241

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

242

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 â from old weather proverbs to modern forecasting equipment â and how improvements in weather technology have saved lives by providing advance warning of natural hazards.

Integrated Teaching And Learning Program

243

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

244

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

245

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…

Forde, Evan B.

2004-01-01

246

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.

1994-01-01

247

Weather Predictions  

NSDL National Science Digital Library

Students will use the internet to learn about weather and play games enhancing their knowledge and interest. Using the knowledge they learned students will write out their prediction of their next 5 days of weather. Intro Task Resources Evaluation Conclusion Teacher Guide Intro Look at the current weather forecast-Click here Current Weather-CNN Task Search for information about what causes different kinds of weather and what instruments people use to predict weather. What is a person called who predicts weather? Resources Resource 1 Resource 2 Resource 3 Resource 4 Resource 5 Resource 6 Evaluation Rubric Conclusion After researching, create your ...

Burr, Miss

2009-03-27

248

Isolation and characterization of silicate mineral-solubilizing Bacillus globisporus Q12 from the surfaces of weathered feldspar.  

PubMed

A silicate mineral-solubilizing bacterial strain Q12 was isolated from the surfaces of weathered feldspar and identified as Bacillus globisporus Q12 based on the 16S rDNA gene sequence analysis. Three silicate minerals (feldspar, muscovite, and biotite) were used to investigate potassium and silicon mobilization by strain Q12. In liquid cultures, the strain showed better growth on the biotite than on feldspar and muscovite. The biotite was the best potassium source for growth of the strain. Solubilization of potassium and silicon from the silicate minerals by the strain resulted mostly from the action of organic acids. Gluconic acid seemed to be the most active agent for the solubilization of the 3 silicate minerals. Gluconic and acetic acids were likely involved in the solubilization of feldspar. The strain could be acid or alkali and salt tolerant and temperature resistant. PMID:19096461

Sheng, Xia Fang; Zhao, Fei; He, Lin Yan; Qiu, Gang; Chen, Liang

2008-12-01

249

Mechanism of surface microcracking of matrix in glass-reinforced polyester by artificial weathering  

Microsoft Academic Search

The first stage in the deterioration of glass-fibre reinforced polyester (GRP) composites, fibre prominence, has been reported. The mechanism of the second stage, surface microcracking, is now described. Under controlled conditions GRP sheets were subjected to cyclic variation of moisture and temperature and to radiation. It is proposed that surface microcracking takes place under the combined action of radiation-induced tensile

A. Blaga; R. S. Yamasaki

1973-01-01

250

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

251

Infrared Land Surface Remote Sensing using High Spectral Resolution Observations  

NASA Astrophysics Data System (ADS)

The authors will describe results of combining high spectral resolution infrared observations with high spatial resolution observations to provide an improved assessment of land surface characteristics. In particular, the high spectral resolution observations of the airborne Scanning-High-resolution Interferometer Sounder (S-HIS)and NPOESS Airborne Sounder Testbed - Interferometer (NAST-I) will be used to derive land surface temperature and infrared emissivity measurements. The MODIS Airborne Simulator (MAS) observations will be used to quantify the sub-pixel land surface variability. Ground truth observations from the Atmospheric Emitted Radiance Interferometer will be presented. The remote sensing techniques will be extended to the satellite based observations of the Interferometeric Monitor for greenhouse Gases (IMG) as well as to simulations of the AIRS and MODIS measurements from the NASA EOS Aqua platform.

Knuteson, R.; Deslover, D.; Larar, A.; Osborne, B.; Revercomb, H.; Short, J.; Smith, W.; Tanamachi, R.

252

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

253

Observing Titan's Surface by Bistatic-Scattering: Cassini's Potential  

NASA Astrophysics Data System (ADS)

Bistatic-scattering is a well-established technique for determination of the nature and physical properties of planets and their satellites. Cassini offers an unprecedented opportunity to observe quasi-specular bistatic-scattering from an icy satellite, potentially at three coherent wavelengths. Circularly-polarized X-, S-, and Ka-band Radio Science signals transmitted from Cassini are observed at the NASA/DSN ground receiving stations after scattering from Titan's surface. Information regarding surface properties is recovered from analysis of the received echo intensity, polarization, and spectral properties. In particular, echo polarization over the Brewster-angle-range of icy surfaces (50-65 deg.) yields direct estimates of the (composite) surface dielectric constant independent of surface roughness (if surface scattering is dominant). Observations over a range of scattering angles yield additional diagnostic information regarding the nature of the scattering mechanism and related physical surface properties (liquid vs. solid, surface vs. volume, surface roughness, etc). The relatively low-altitude of many Titan flybys (950 km) yields excellent to good SNR within 15 minutes from closest-approach (C/A), even for surface reflectivity of only a few percent. In addition, the close flybys enhance potential echo detectability at all three wavelengths, yielding a wealth of information regarding dispersive characteristics of the scattering mechanism. More limited X-band-only observations may be achieved at fair SNR within roughly 40 minutes from C/A. The bistatic-scattering observations over a range of quasi-specular scattering angles provide excellent synergy to the backscattering-limited Earth-based-radar as well as Cassini RADAR observations. Support by the NASA/JPL Cassini Project is acknowledged.

Marouf, E.; French, R.; Rappaport, N.; Kliore, A.

2000-10-01

254

Weather & Weather Maps. Teacher's Manual.  

ERIC Educational Resources Information Center

This guide is intended to provide an opportunity for students to work with weather symbols used for reporting weather. Also included are exercises in location of United States cities by latitude and longitude, measurement of distances in miles and kilometers, and prediction of weather associated with various types of weather fronts. (RE)

Metro, Peter M.; Green, Rachel E.

255

Using Forecasting to Teach Weather Science  

NASA Astrophysics Data System (ADS)

Weather affects our lives and hence, is a popular topic in daily conversations and in the media. Therefore, it is not only important to teach weather, but is also a good idea to use 'weather' as a topic in science teaching. Science education has two main objectives: to acquire scientific concepts and methods. Weather forecasting is an adequate theme to teach scientific methods because it is dependent on observation. However, it is not easy to forecast weather using only temporal observation. We need to know the tendency of 'weather change' via consecutive and/or continuous weather observation. Students will acquire scientific-observation skills through weather observation. Data-processing skills would be enhanced through a weather-forecasting contest. A contest should be announced within 5 days of school events, such as a school excursion and field day. Students submit their own weather forecast by gathering weather information through the internet, news paper and so on. A weather-forecasting contest compels the student to observe the weather more often. We currently have some different weather forecasts. For example, American weather-related companies such as ACCU weather and Weather Channel provide weather forecast for the many locations all over the world. Comparing these weather forecasting with actual weather, participants such as students could evaluate the differences between forecasted and actual temperatures. Participants will judge the best weather forecast based on the magnitude of the difference. Also, participants evaluate the 'hitting ratio' of each weather forecast. Students can learn elementary statistics by comparing various weather forecasts. We have developed our weather web-site that provides our own weather forecasting and observation. Students acquire science skills using our weather web-site. We will report our lessen plans and explain our weather web-site.

Tsubota, Y.; Takahashi, T.

2009-09-01

256

Spectral Evidence of Size Dependent Space Weathering Processes on Asteroid Surfaces.  

National Technical Information Service (NTIS)

Most compositional characterizations of the minor planets are derived from analysis of visible and near-infrared reflectance spectra. However, such spectra are derived from light which has only interacted with a very thin surface layer. Although regolith ...

M. J. Gaffey J. F. Bell R. H. Brown T. H. Burbine J. L. Piatek

1993-01-01

257

Correlation between ground weather radar and satellite observations at microwaves for the Grímsvötn volcanic eruption on May 2011  

NASA Astrophysics Data System (ADS)

The potential use of passive and active microwaves sensors to provide quantitative information about near-source volcanic ash cloud parameters during an eruptive event is analyzed in this work from an experimental point of view. To this aim ground-based microwave (MW) weather radar and satellite MW radiometer observations are used together. The target area where the collected measurements are compared is the Icelandic subglacial volcanic region and the analyzed case study is that of the Grímsvötn eruption on May 2011. The analyzed weather radar data include those of the Keflavík (Iceland) site (260 km far from the volcano vent) operating at single polarization and working at the frequency of 5.6 GHz with a range resolution of 2 km and that of a portable radar system positioned 70 km far from the volcano vent with polarimetry capabilities (i.e. able to measure signals from both the orthogonal polarizations of the backscattered power as well as the phase shift returns) and working at the frequency of 10 GHz with a range spatial resolution of 0.25 km. On the other hand, the measurements from the satellite passive radiometer are derived from the Special Sensor Microwave Imager/Sounder (SSMIS) in terms of brightness temperature. SSMIS is a conically scanning passive microwave radiometer aboard of a low-earth- orbit platform with several channels (from about 19 GHz to 189 GHz) and with a ground resolution variable from 12.5 and 25 km depending from the frequency channel used. The diversity in terms of spatial scale, frequency, polarization and observation point of view of the collected data gives an original contribution to the characterization of the near source parameters of the Grímsvötn eruption in May 2011 highlighting the advantages and drawbacks of microwave sensors used for volcanic purposes. Traditionally, the monitoring of ash plumes is performed exploiting thermal infrared (TIR) and optical channels of spaceborne radiometers. These measurements can be obtained from sensors aboard geosynchronous-earth-orbit (GEO) and low-earth- orbit (LEO) satellites, thus offering different spatial and temporal resolutions for ash cloud remote sensing. For GEO platforms the advantage of rapid sampling of the earth scene is paid with lower resolution (typically larger than few kilometers), whereas for LEO the revisit time may be even longer than 12 hours. Moreover, TIR and optical channels may suffer from strong ash cloud opacity (very often mixed with water cloud) due to the significant radiation extinction especially in the proximity of the volcanic source. In this respect, the exploitation of the microwave (MW) passive sensors may represent a good opportunity due to their capability to sound the ash cloud, though with some inherent limitations. The results of this work will be shown in terms of correlation between the passive satellite-based brightness temperatures and active ground based retrievals of ash content. The latter is obtained applying the Volcanic Ash Radar Retrieval (VARR) technique both on single and dual polarization mode. The advantage of using the ground based radar orthogonal-polarization measurements will be preliminarily discussed.

Montopoli, Mario; Cimini, Domenico; Vulpiani, Gianfranco; Marzano, Frank S.

2013-04-01

258

STM observation of steps and terraces on tungsten (211) surface.  

PubMed

Thermally cleaned W(211) surface with 0.7 degrees miscut consists of (211) terraces separated by monoatomic steps. When the surface is exposed to oxygen and subsequently annealed at 1100-1900 K, the width of (211) terraces increases and multilayer steps are formed. Similar step bunching is observed during routine cleaning of the sample by annealing in oxygen and thermal flashing in ultra high vacuum. During such cleaning procedure islands of c(6 x 4) reconstruction are observed. PMID:12535561

Zuber, S M; Szczud?o, Z; Szczepkowicz, A; Losovyi, Ya B; Ciszewski, A

259

Backyard Weather Stations  

NSDL National Science Digital Library

Learn how to build your own backyard weather station with complete directions provided by FamilyEducation.com's Web site, Backyard Weather Stations. The site shows exactly what you'll need and how to build the necessary components (e.g., rain gauge and barometer), as well as how to keep records of the data collected. Parents and teachers will enjoy watching the kids "learn the basics of scientific observation and record-keeping while satisfying their natural curiosity about weather."

Randall, Dennis.

260

U. S. Naval Weather Service Command Summary of Synoptic Meteorological Observations: East African and Selected Island Coastal Marine Areas. Volume 2. Area 7 - Red Sea South, Area 8 - Red Sea South Central, Area 9 - Red Sea Central, Area 11 Red Sea North Central, Area 11 - Red Sea North, Area 12 - Gulf of Suez.  

National Technical Information Service (NTIS)

The data contained in these tables were obtained from tape data Family 11 (TDF-11), Marine Surface observations. TDF-11 was primarily funded by the Naval Weather Service Command and selected by NWSED Asheville as the most comprehensive collection of marin...

1974-01-01

261

U.S. Naval Weather Service Command Summary of Synoptic Meteorological Observations - East African and Selected Island Coastal Marine Areas. Volume 3. Area 13 - Gulf of Aden, SW, Area 14 - Gulf of Aden, SE, Area 15 - Somali Coast, NE, Area 16 - Somali Coast East, Area 17 - Somali Coast, SE, Area 18 - Somali Coast South.  

National Technical Information Service (NTIS)

The data contained in these tables were obtained from tape data Family 11 (TDF-11), Marine Surface observations. TDF-11 was primarily funded by the Naval Weather Service Command and selected by NWSED Asheville as the most comprehensive collection of marin...

1974-01-01

262

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

263

Small-scale diffusion experiments in the Baltic surface-mixed layer under different weather conditions  

Microsoft Academic Search

During the experiment “Baltic '75” east of Bornholm, in May 1975 dye mixing experiments were carried out in the surface-mixed layer on scales of less than a few hundred meters. The dye was measured by aerial photography and synoptic concentration distributions were calculated from the colour photographs by a computerized processing method and by use of a towed fluorometer for

Friedrich Schott; Mafred Ehlers; Lutz Hubrich; Detlef Quadfasel

1978-01-01

264

Observation of water condensate on hydrophobic micro textured surfaces  

NASA Astrophysics Data System (ADS)

We visually observed that a dropwise condensation occurred initially and later changed into a filmwise condensation on hydrophobic textured surface at atmosphere pressure condition. It was observed that the condensate nucleated on the pillar side walls of the micro structure and the bottom wall adhered to the walls and would not be lifted to form a spherical water droplet using environmental scanning electron microscope.

Kim, Ki Wook; Do, Sang Cheol; Ko, Jong Soo; Jeong, Ji Hwan

2013-07-01

265

SPECIFIC CONTRIBUTIONS TO THE OBSERVING SYSTEM: SEA SURFACE TEMPERATURES  

Microsoft Academic Search

Sea surface temperature (SST) observations have been made from in situ (ship and buoy) and satellites. SST analyses used for climate purposes must be constant in time and not influenced by the changes that have occurred in the type and number of SST observations. In particular, biases due to in situ instrument changes and satellite aerosol and cloud contamination must

Richard W. REYNOLDS

266

Contrail Frequency over the United States from Surface Observations  

Microsoft Academic Search

Contrails have the potential for affecting climate because they impact the radiation budget and the vertical distribution of moisture. Estimating the effect requires additional knowledge about the temporal and spatial variations of contrails. The mean hourly, monthly, and annual frequencies of daytime contrail occurrence are estimated using 2 yr of observations from surface observers at military installations scattered over the

Patrick Minnis; J. Kirk Ayers; Michele L. Nordeen; Steven P. Weaver

2003-01-01

267

Studying Two Extreme Years Using Both Surface-Satellite Observations and NCEP Reanalysis  

NASA Astrophysics Data System (ADS)

A total of 11 years (1997-2007) surface and satellite observations have been collected over the DOE ARM SGP site, including the two extreme years: dry 2006 and wet 2007. The observations include the cloud fraction derived from both ARM radar/lidar and GOES satellite observations, surface precipitation measured by rain gauge, and surface radiation budget and temperature. The NCEP North American Regional Reanalysis (NARR) dataset has also been collected for studying the impact of large-scale dynamics on the dry and wet extremes over SGP. Preliminary results have shown that the cloud fraction during the dry 2006 is 10% (relative) below and precipitation is 40% less than the 11-yr (1997-2007) averages. The feedback mechanisms have been reflected as follow: with less clouds and precipitation, the downwelling SW flux increased 7.1 Wm-2 and surface temperature rose 1.1 K during the dry 2006. This additional warming can strengthen an existing drought. The general circulation over Central U.S. is the west-to-east circulation pattern during normal years. During the dry 2006, however, an abnormal high located over Southwest of U.S. with subsidence of dry/cold air and little chance for precipitation. This abnormal high blocked the inflow of low-level moisture from Gulf of Mexico and further reinforced the dry weather pattern. In this study, we will use combined satellite-surface observations and NCEP reanalysis to explore two primary questions: 1. How do seasonal and diurnal cycles of observed water and energy change in dry versus wet years, as well as their severities compared to the normal years? 2. To what extent do the large-scale dynamics play a role in controlling the extremes?

Dong, X.; Xi, B.; Kennedy, A.

2008-05-01

268

Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations  

Microsoft Academic Search

Historic sandstone structures carry an inheritance, or a `memory', of past stresses that the stone has undergone since its placement in a façade. This inheritance, which conditions present day performance, may be made up of long-term exposure to a combination of low magnitude background environmental factors (for example, salt weathering, temperature and moisture cycling) and, superimposed upon these, less frequent

S. McCabe; B. J. Smith; P. A. Warke

2007-01-01

269

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

Microsoft Academic Search

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,

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

2009-01-01

270

Lunar Far-UV Dayside Albedo Maps: LRO/LAMP Investigations of Surface Hydration and Space Weathering  

NASA Astrophysics Data System (ADS)

The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is currently mapping the lunar albedo at far-UV wavelengths. LAMP primarily measures faint interplanetary HI Lyman-alpha sky-glow and far-UV starlight reflected from the nightside lunar surface to pioneer an innovative technique for studying the permanently shadowed regions (PSRs) near the poles. Far-UV reflectance measurements of the bright lunar dayside are also frequently obtained. LAMP dayside measurements utilize a "pinhole" aperture with a factor of 736 less throughput to obtain a comparable dynamic range of detector count rates as for the nightside measurements. Initial spectral analysis of broad ( 10 deg latitude) regions within the dayside dataset indicate evidence for latitudinal and diurnal trends that are diagnostic of surface hydration and space weathering, as reported by Hendrix et al. 2012. We report initial results from follow on analyses of high spatial resolution maps produced using the LAMP dayside reflectance dataset.

Retherford, Kurt D.; Hendrix, A. R.; Gladstone, G. R.; Stern, S. A.; Miles, P. F.; Egan, A. F.; Kaufmann, D. E.; Feldman, P. D.; Hurley, D. M.; Greathouse, T. K.; Parker, J. W.; Bayless, A. J.; Davis, M. W.; Cook, J. C.; Mukherjee, J.

2012-10-01

271

Chemical weathering and related controls on surface water chemistry in the Absaroka Mountains, Wyoming  

Microsoft Academic Search

Chemical relationships among surface waters, soils and rocks were investigated in the drainage basin of the North Fork of the Shoshone River in northwestern Wyoming. The area is underlain entirely by andesitic volcanic rocks. Smectite is the only clay mineral forming in soils over much of the area, although minor kaolinite occurs in a few areas of higher-than-average rainfall. Mass-balance

William R. Miller; James I. Drever

1977-01-01

272

Mars surface phase function constrained by orbital observations  

NASA Astrophysics Data System (ADS)

The bidirectional photometric properties of the surface of Mars describe how remote measurements of surface reflectance can be linked to hemispherical albedo used for energy balance calculations. A simple Lambert's law is frequently assumed for global data processing, even though several local studies have revealed the complexity of Mars surface phase functions. In this paper, we derive a mean Bidirectional Reflectance Distribution Function (BRDF) representative of widespread typical Martian terrains. OMEGA and CRISM orbital observations are used to provide observational constraints at solar wavelengths over a wide range of viewing conditions all over the planet. Atmospheric contribution is quantified and removed using a radiative transfer model. We observe a common phase behavior consisting of a 5%-10% backscattering peak and, outside the backscattering region, a 10%-20% reflectance increase with emergence angles. Consequently, nadir measurements of surface reflectance typically underestimate hemispherical reflectance, or albedo, by 10%. We provide a parameterization of our mean Mars surface phase function based on Hapke formalism (?=0.85, ?=17, c=0.6, b=0.12, B0=1 and h=0.05), and quantify the impact of the diffuse illumination conditions which change surface albedo as a function of local time and season. Our average phase function can be used as a refinement compared to the Lambertian surface model in global data processing and climate modeling.

Vincendon, Mathieu

2013-02-01

273

Weather Watchers  

NSDL National Science Digital Library

In this lesson, students learn how meteorologists measure the weather by examining some online, real-time data resources and collaborating to create an in-class weather station that tracks local weather patterns for one week. Students compare this information to weather patterns in two other locations. After completing this lesson, students should be able to explain ways that meteorologists measure and predict weather and use the Internet to research information about weather conditions in various locations in the United States, including their hometown. Students will also collaborate on creating some weather-measurement instruments and keep a weather journal for one week. This site provides an overview of the lesson, detailed procedures for the teacher, including a list of research sites, and an organizational path for students.

274

Mechanical Weathering  

NSDL National Science Digital Library

This activity was designed to give students an opportunity to realize that all rocks weather mechanically and each specific rock type has its own particular rate of weathering. Students discover that mechanical weathering is the process of breaking down bedrock into smaller fragments by physical as opposed to chemical means and that rock weathering, although it seems to occur slowly in human terms, is an extremely significant part of the rock cycle. They will learn that weathered rock materials are called sediments and are the structural basis for soils and can also be compacted into sedimentary rock. Students will realize that rock weathering rates vary widely depending on mineral content, texture, rock type, and climate and that differential weathering (varying weathering rates for two or more rock types in physical contact with each other) has given rise to some of the world's most breathtaking scenery.

275

Weather Talk  

NSDL National Science Digital Library

Weather Talk is a primer on weather and naval meteorology. It provides a brief overview of major weather elements and is presented in a non-mathematical way, so that the reader will have a better understanding of the basic mechanisms of weather and use it to their advantage and safety in planning and carrying out their own activities. The site explains temperature, wind, pressure, atmospheric moisture, air masses and fronts, thunderstorms, tornadoes, hurricanes, and climatology.

276

Dynamic Characteristics of the Main Indexes of Space Weather and Their Application to the Analysis Monitoring Observations Flux Densities of Power Radio Sources on RT  

NASA Astrophysics Data System (ADS)

On radio telescope "URAN-4" of the Odessa observatory of Radio-astronomical Institute during twenty five years (since 1987 till present) monitoring of power galactic and extragalactic radio sources on frequencies 25 and 20MHz has been carried out. Data of the observation was spent in a current of the 22-23th cycles of solar activity and in the beginning of the 24th cycle. Long-term variations density fluxes of radio sources connection with change of a condition of ionosphere in a cycle of solar activity are considered. Means Fourier and Wavelet analysis determine dynamics of changes of the main indexes of space weather and the basic periods of activity are revealed. The obtained data will be used for interpretation of the observation changes flux of radio sources for during all investigated cycle of activity and periods of extreme developments of space weather.

Guglya, L.; Ryabov, M.; Panishko, S.; Suharev, A.

277

Surface-Atmosphere exchanges in urban areas: Observations and models  

NASA Astrophysics Data System (ADS)

Increasing attention is being directed to the climates of urban areas given a large and increasing proportion of the worlds population live in cities, and urban settings are the locations of some of the most profound human impacts on the natural environment. Although understanding of urban effects on climate is incomplete, over the last decade much has been learnt about how urbanization modifies the climate system at micro, local and meso-scales, and the variability both within and between cities. This paper will attempt to summarize the most significant findings of this research. Data on the fundamental energy, mass and momentum exchanges will be presented from measurements campaigns from cities across North America (Vancouver, Mexico City, Los Angeles, Chicago, Sacramento, Tucson, Oklahoma City, Baltimore); Europe (Lodz, Marseille); and Africa (Ouagadougou), along with results of evaluations of simple (LUMPS-NARP and UK Met-Office) to more complex (TEB) surface-atmosphere exchange schemes, appropriate for use in global circulation, numerical weather prediction, and regional land-atmosphere models.

Grimmond, S.; Oke, T. R.

2003-12-01

278

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

279

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

280

Thermophysics During the MER Spirit Winter Campaign: Observing Complex Surfaces Through Seasonal and Diurnal Cycles  

Microsoft Academic Search

In this work, we quantify the response of surface temperature to subsurface layers, local weather variations, and seasonal processes at the MER Spirit landing site region. Previous thermophysical work at the MER landing sites include deriving thermal inertia values of dusty, sandy, and rocky surfaces, and comparing the thermally derived particle size with those measured directly using Pancam and MI

R. L. Fergason; P. R. Christensen; R. E. Arvidson

2006-01-01

281

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

282

Observation of Surface Layering in a Nonmetallic Liquid  

SciTech Connect

Oscillatory density profiles (layers) have previously been observed at the free surfaces of liquid metals but not in other isotropic liquids. We have used x-ray reflectivity to study a molecular liquid, tetrakis(2-ethylhexoxy)silane. When cooled to T/T{sub c}{approx}0.25 (well above the freezing point for this liquid), density oscillations appear at the surface. Lateral order within the layers is liquidlike. Our results confirm theoretical predictions that a surface-layered state will appear even in dielectric liquids at sufficiently low temperatures, if not preempted by freezing.

Mo,H.; Evmenenko, G.; Kewalramani, S.; Kim, K.; Ehrlich, S.; Dutta, P.

2006-01-01

283

Magnetopause surface waves: THEMIS observations compared to MHD theory  

NASA Astrophysics Data System (ADS)

On 5 and 6 October 2011, the three inner THEMIS spacecraft observed oscillatory magnetopause (MP) motion in the early afternoon sector over extended periods of time, caused by the passage of surface waves. The close configuration of the spacecraft tangential to the MP allowed for determination of wave propagation velocities via cross-correlation analysis. This enabled us to compare observations with solutions of the surface wave dispersion relation derived in the framework of ideal MHD theory. We find that observations and theoretical predictions are in quantitative agreement if a high plasma flow velocity (of around 340 km/s) can be assumed in the plasma depletion layer on the magnetosheath side of the MP. Although the surface waves propagated more slowly than the plasma on the magnetosheath side, they were not subject to the Kelvin-Helmholtz instability. We suggest that waves generated in the quasi-parallel bow shock or upstream foreshock regions may have impinged on the MP generating the surface waves. Additionally, the spacecraft separation in the boundary normal direction enabled us to infer directly the waveform and MP boundary layer structure. Interestingly, the trailing edges of the waves were more inclined than the leading edges, contrary to theory and prior observations of Kelvin-Helmholtz-driven surface waves.

Plaschke, F.; Angelopoulos, V.; Glassmeier, K.-H.

2013-04-01

284

Observation and modeling of land surface state and convective activity over the Qinghai - Tibet Plateau  

NASA Astrophysics Data System (ADS)

The Qinghai - Tibet Plateau is characterized by a significant intra-annual variability and spatial heterogeneity of surface conditions. Snow and vegetation cover, albedo, surface temperature and wetness change very significantly during the year and from place to place. The influence of temporal changes on convective events and the onset of the monsoon has been documented by ground based measurements of land - atmosphere exchanges of heat and water. The state of the land surface over the entire Plateau can be determined by space observation of surface albedo, temperature, snow and vegetation cover and soil moisture. This provides spatial patterns in the land surface drivers of atmospheric instability: radiative forcing, land surface temperature and soil moisture contribute to trigger convective events. Heat and vapour fluxes at the land surface have been mapped at high spatial resolution and over periods of time representative of seasonal variability using MODIS and AATSR multispectral radiometric data. The response of surface temperature to vegetation phenology has been studied by using 25 years of AVHRR observations. Snow cover has been monitored by improving and re-calibrating the MODIS snow cover product. The snow water equivalent has been monitored over a period of 28 years using SMMR and SSM/I 18 and 37 GHz data and an improved algorithm. Linkages between land surface conditions, convective events and the onset of the Asian Monsoon have been investigated using two Numerical Weather Prediction Models: GRAPES in China and WRF in Japan to analyze a set of case-studies. These first experiments were aimed at evaluating the linkages of land surface conditions with intense rainfall events in the region. Using the modeling and data assimilation system GRAPES a series of experiments was performed to assess the sensitivity to different types of Land Surface Models. Combined use of medium resolution thermal infrared sensors like AATSR or MODIS with GRAPES in a Multi-Scale Surface Energy Balance System has provided turbulent flux maps at a kilometric resolution on the entire Tibetan Plateau. Both meso and local scale approaches are compared and discussed to analyse the effect of sub-grid heterogeneity on land surface and turbulent flux parameterisation.

Menenti, M.; Colin, J.; Jia, L.; Ma, Y.; Foken, T.; Sobrino, J.; Wang, J.; Ueno, K.

2010-12-01

285

Observation and modeling of land surface state and convective activity over the Qinghai - Tibet Plateau  

NASA Astrophysics Data System (ADS)

The Qinghai - Tibet Plateau is characterized by a significant intra-annual variability and spatial heterogeneity of surface conditions. Snow and vegetation cover, albedo, surface temperature and wetness change very significantly during the year and from place to place. The influence of temporal changes on convective events and the onset of the monsoon has been documented by ground based measurements of land - atmosphere exchanges of heat and water. The state of the land surface over the entire Plateau can be determined by space observation of surface albedo, temperature, snow and vegetation cover and soil moisture. This provides spatial patterns in the land surface drivers of atmospheric instability: radiative forcing, land surface temperature and soil moisture contribute to trigger convective events. Heat and vapour fluxes at the land surface have been mapped at high spatial resolution and over periods of time representative of seasonal variability using MODIS and AATSR multispectral radiometric data. The response of surface temperature to vegetation phenology has been studied by using 25 years of AVHRR observations. Snow cover has been monitored by improving and re-calibrating the MODIS snow cover product. The snow water equivalent has been monitored over a period of 28 years using SMMR and SSM/I 18 and 37 GHz data and an improved algorithm. Linkages between land surface conditions, convective events and the onset of the Asian Monsoon have been investigated using two Numerical Weather Prediction Models: GRAPES in China and WRF in Japan to analyze a set of case-studies. These first experiments were aimed at evaluating the linkages of land surface conditions with intense rainfall events in the region. Using the modeling and data assimilation system GRAPES a series of experiments was performed to assess the sensitivity to different types of Land Surface Models. Combined use of medium resolution thermal infrared sensors like AATSR or MODIS with GRAPES in a Multi-Scale Surface Energy Balance System has provided turbulent flux maps at a kilometric resolution on the entire Tibetan Plateau. Both meso and local scale approaches are compared and discussed to analyse the effect of sub-grid heterogeneity on land surface and turbulent flux parameterisation.

Menenti, M.; Colin, J.; Jia, L.; Ma, Y.; Foken, T.; Sobrino, J. A.; Wang, J.; Shen, X.; Ueno, K.

2012-04-01

286

Generation of global surface albedo data set from archived geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Monitoring and understanding climate changes of the Earth require the generation of long-term and consistent global data set from observation. In this context, geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives, often covering more than two decades. In particular, their frequent cycle of acquisition can be used to document the anisotropy of the surface and thereby surface albedo. Hence, EUMETSAT has developed the so-called Geostationary Surface Albedo (GSA) algorithm based on an algorithm proposed by Pinty et al. This algorithm is capable of processing observations of any geostationary satellites to derive the surface albedo, accounting for the effects of the surface anisotropy and the aerosols. This algorithm has been implemented in the Operational reprocessing facility of EUMETSAT in order to generate reliable albedo dataset starting from the 1982, through the analysis of data acquired by the six different Meteosat first generation platforms for the satellites located at the 0 degree longitude. Observations acquired by the EUMETSAT satellites located over the Indian Ocean since 1998 have also been processed. The GSA algorithm has also been implemented at the Japanese Meteorological Agency (JMA) for the processing of the GMS-5 archive. EUMETSAT has the responsibility to integrate all these level-2 products into a unique level-3 broadband surface albedo product. The evaluation of this global surface albedo product relies on the comparison of pairs of contemporaneous products generated from two adjacent satellites sharing a common observation area and with the equivalent MODIS product. This latter comparison has revealed that both products agree within 10% relative difference. This study is performed under the framework of the Co-Ordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) project, a WMO initiative to establish a network of facilities ensuring continuous and sustained provision of high-quality satellite products related to the Essential Climate Variables (ECV), on a global scale, responding to the requirements of the Global Climate Observing system (GCOS). It demonstrates the contribution of operational weather satellites into the generation of consistent time series of surface albedo.

Govaerts, Yves; Okuyama, Arata; Latanzio, Alessio

2010-05-01

287

Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations  

Microsoft Academic Search

Historic sandstone structures carry an inheritance, or a ‘memory’, of past stresses that the stone has undergone since its\\u000a placement in a façade. This inheritance, which conditions present day performance, may be made up of long-term exposure to\\u000a a combination of low magnitude background environmental factors (for example, salt weathering, temperature and moisture cycling)\\u000a and, superimposed upon these, less frequent

S. McCabe; B. J. Smith; P. A. Warke

2007-01-01

288

Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations  

NASA Astrophysics Data System (ADS)

Historic sandstone structures carry an inheritance, or a ‘memory’, of past stresses that the stone has undergone since its placement in a façade. This inheritance, which conditions present day performance, may be made up of long-term exposure to a combination of low magnitude background environmental factors (for example, salt weathering, temperature and moisture cycling) and, superimposed upon these, less frequent but potentially high magnitude events or ‘exceptional’ factors (for example, lime rendering, severe frost events, fire). The impact of complex histories on the decay pathways of historic sandstone is not clearly understood, but this paper seeks to improve that understanding through the use of a laboratory ‘process combination’ study. Blocks of quartz sandstone (Peakmoor, from NW England) were divided into subsets that experienced different histories (lime rendering and removal, fire and freeze-thaw cycles in isolation and combination) that reflected the event timeline of a real medieval sandstone monument in NE Ireland, Bonamargy Friary (McCabe et al. 2006b). These subsets were then subject to salt weathering cycles using a 10% salt solution of NaCl and MgSO4 that represents the ‘every-day’ stress environment of, for example, sandstone structures in coastal, or polluted urban, location. Block response to salt weathering was monitored by collecting, drying and weighing the debris that was released as blocks were immersed in the salt solution at the beginning of each cycle. The results illustrate the complexity of the stone decay system, showing that seemingly small variations in stress history can produce divergent response to salt weathering cycles. Applied to real-world historic sandstone structures, this concept may help to explain the spatial and temporal variability of sandstone response to background environmental factors on a single façade, and encourage conservators to include the role of stress inheritance when selecting and implementing conservation strategies.

McCabe, S.; Smith, B. J.; Warke, P. A.

2007-03-01

289

Unmanned aerial observation of the Planetary Boundary Layer for model evaluation and weather prediction purposes in support of UAV operation  

NASA Astrophysics Data System (ADS)

Meteorological information is a key factor in aviation, especially in unmanned (UAV) operations where actual intervention is not possible in case of unforeseen weather hazards. For the development of an aviation meteorology system in support of UAV operation, various research activities have been initiated recently in Hungary. This activity included statistical analysis of historical weather data, numerical weather prediction model development and in situ measurements with the UAV airframe itself. The aim of our current presentation is the introduction of the planned meteorological survey system. Model development includes the comparison test of different model setup in various selected meteorological situations (widespread precipitation, strong wind condition, strong inversions, significant wind veering, deep convection, frontal activity, icing, mid-tropopause cold vortex). The output of meteorological forecast model is post-processed for the special needs of aviation, including the forecast of visibility/low cloudbase, icing, turbulence, windshear, etc. The model results can be verified using UAV based measurements. The airframe, which is a special Hungarian development light unmanned aircraft, is also introduced. The first results of measurements and their comparison to model predictions are also presented.

Zeno Gyongyosi, Andras; Kurunczi, Rita; Kardos, Peter; Bottyan, Zsolt; Weidinger, Tamas; Istenes, Zoltan; Szabo, Zoltan

2013-04-01

290

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

291

Wind Measurement and Archival under the Automated Surface Observing System (ASOS): User Concerns and Opportunity for Improvement.  

NASA Astrophysics Data System (ADS)

The National Weather Service, as a part of its modernization effort, is implementing the Automated Surface Observing System (ASOS). Much discussion has occurred about various aspects of ASOS versus the current system of manual and automated observations. Based upon a study of the ASOS specifications and an informal survey of potential ASOS winddata users, defects of the wind sampling and archival strategy chosen for ASOS are discussed in terms of their impact on various user groups. Limitations include: 1) hourly observation average periods that do not conform to international recommendations for wind reporting made by the World Meteorological Organization, 2) no regular archival of high-resolution data-potentially valuable research data are destroyed if not identified within a 12-h period, and 3) no emergency power for operation in severe weather conditions. An alternative sampling and archiving strategy is recommended that benefits a wider cross section of users, without detracting from aviation and forecast service requirements, at a cost of less than 1% of the original ASOS portion of the weather service modernization budget.

Powell, Mark D.

1993-04-01

292

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.

Salvucci, Guido D.; Gentine, Pierre

2013-01-01

293

Calibrating riverbed friction using remotely sensed observations of surface currents  

NASA Astrophysics Data System (ADS)

Reliable estimates of bed friction coefficients are essential for numerical prediction of river currents and sediment transport. One approach of estimating bed friction involves iterative calibration of the friction coefficient until the numerically predicted water level profile matches a set of observed water levels. Alternatively, the numerical model can be calibrated by matching predicted and observed depth-averaged velocity across a set of cross-sections. Motivated by recent advances in high resolution remote sensing, we investigate whether surface currents, either estimated from remotely sensed imagery or measured in situ from drifters, can be used to calibrate bed friction in river flow simulations with the FASTMECH numerical model. Remotely sensed and in situ observations were performed on the Kootenai River near Bonners Ferry, Idaho during August 2010. We use in situ measurements of velocity profiles obtained with an acoustic Doppler current profiler to relate measured surface currents and depth averaged velocity. Friction estimates based on surface velocity calibration are compared to estimates based on in situ water level measurements. Additionally, using surface velocity measurements to calibrate friction leads to simulated surface water level estimates that have an associated error and vice versa. We will discuss the difference in relative errors and the advantages/disadvantages of each approach to estimating bed roughness.

Holland, K.; Simeonov, J.; Calantoni, J.

2011-12-01

294

STS Observations of Landau Levels at Graphite Surfaces  

Microsoft Academic Search

Scanning tunneling spectroscopy (STS) measurements were made on surfaces of two different kinds of graphite samples, Kish graphite and highly oriented pyrolytic graphite (HOPG), at very low temperatures and in high magnetic fields. We observed a series of peaks in the tunnel spectra associated with Landau quantization of the quasi-two-dimensional electrons and holes. A comparison with the calculated local density

T. Matsui; H. Kambara; Y. Niimi; K. Tagami; M. Tsukada; Hiroshi Fukuyama

2005-01-01

295

Supergranular waves observed using MDI surface Doppler shift data  

NASA Astrophysics Data System (ADS)

Recently Gizon, Duvall and Schou (2002) suggested that supergranulation has a wave-like component. Here I show that the phenomenon can also be observed using surface Doppler shift data and extend their results. I also show results for rotation and meridional flows beyond ±70° latitude inferred using the supergranular waves and look for temporal variations in the various properties.

Schou, Jesper

2003-02-01

296

Diurnal variations of Titan's surface temperatures from Cassini - CIRS observations  

Microsoft Academic Search

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 micron (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered

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

2010-01-01

297

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

Microsoft Academic Search

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

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

2010-01-01

298

Titan's Surface Temperatures Maps from Cassini - CIRS Observations  

Microsoft Academic Search

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 mum (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered

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

2009-01-01

299

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...

300

Large Scale Surface Radiation Budget from Satellite Observation  

NASA Astrophysics Data System (ADS)

During the current reporting period, the focus of our work was on preparing and testing an improved version of our Surface Radiation Budget algorithm for processing the ISCCP D1 data routinely at the SRB Satellite Data Analysis Center (SDAC) at NASA Langley Research Center. The major issues addressed are related to gap filling and to testing whether observations made from ERBE could be used to improve current procedures of converting narrowband observations, as available from ISCCP, into broadband observations at the TOA. The criteria for selecting the optimal version are to be based on results of intercomparison with ground truth.

Pinker, R. T.

1995-12-01

301

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)

1995-10-01

302

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 micron (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). 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.

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

2010-04-01

303

Weather and Climate.  

National Technical Information Service (NTIS)

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 lo...

1975-01-01

304

Experimental observation of quantum oscillation of surface chemical reactivities  

PubMed Central

Here we present direct observation of a quantum reactivity with respect to the amounts of O2 adsorbed and the rates of surface oxidation as a function of film thickness on ultrathin (2–6 nm) Pb mesas by scanning tunneling microscopy. Simultaneous spectroscopic measurements on the electronic structures reveal a quantum oscillation that originates from quantum well states of the mesas, as a generalization of the Fabry–Pérot modes of confined electron waves. We expect the quantum reactivity to be a general phenomenon for most ultrathin metal films with broad implications, such as nanostructure tuning of surface reactivities and rational design of heterogeneous catalysts.

Ma, Xucun; Jiang, Peng; Qi, Yun; Jia, Jinfeng; Yang, Yu; Duan, Wenhui; Li, Wei-Xue; Bao, Xinhe; Zhang, S. B.; Xue, Qi-Kun

2007-01-01

305

Soil weathering rates in 21 catchments of the Canadian Shield  

NASA Astrophysics Data System (ADS)

Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K) for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha-1 yr-1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64) with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51 %. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas as well as adequately predict absolute weathering rates values for the sum of base cations, Ca and Mg.

Houle, D.; Lamoureux, P.; Bélanger, N.; Bouchard, M.; Gagnon, C.; Couture, S.; Bouffard, A.

2011-06-01

306

Soil weathering rates in 21 catchments of the Canadian Shield  

NASA Astrophysics Data System (ADS)

Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K) for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha-1 yr-1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64) with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51%. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas as well as adequately predict absolute weathering rates values for the sum of base cations, Ca and Mg.

Houle, D.; Lamoureux, P.; Bélanger, N.; Bouchard, M.; Gagnon, C.; Couture, S.; Bouffard, A.

2012-03-01

307

Ensemble square root filter assimilation of near-surface soil moisture and reference-level observations into a coupled land surface-boundary layer model  

NASA Astrophysics Data System (ADS)

The potential for using the ensemble square root filter data assimilation technique to estimate soil moisture profiles, surface heat fluxes, and the state of the planetary boundary layer (PBL) is explored. An observing system simulation experiment is designed to mimic the assimilation of near-surface soil moisture observations ( ?°) and in-situ measurements of 2-m temperature ( T°), 2-m specific humidity ( Q°), and 10-m horizontal winds [ V°=( U°, V°)]. The background forecasts are generated by a one-dimensional coupled land surface-boundary layer model (CLS-BLM) with soil, surface-layer and PBL parameterization schemes similar to those used in the Weather Research and Forecasting (WRF) model. Soil moisture, surface heat fluxes, and the state of the PBL evolve on different characteristic timescales, so the minimum assimilation time intervals required for skillful estimates of each target component are different. Correct estimates of the soil moisture profile are obtained effectively when a 6-h update time interval is used, while skillful estimates of surface fluxes and the PBL state require more frequent updates. The CLS-BLM requires a shorter assimilation time interval to correctly estimate the soil moisture profile than previously indicated by experiments using an off-line land surface model (LSM). Results from assimilating different subsets of observations show that ?° makes a larger contribution to soil moisture estimates, while T°, ?°, and V° are more important for estimates of surface heat fluxes and the PBL state. It is therefore necessary to combine these variables to accurately estimate the states of both the land surface and the PBL. Experimentation with different prescribed observational errors shows that the assimilation system is more sensitive to increases in observational errors than to reductions in observational errors.

Zhang, Shuwen; Liu, Yanhua; Zhang, Weidong

2013-08-01

308

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

309

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 ...

Harris, Ms.

2011-01-24

310

Combined Satellite- and Surface-Based Observations of Clouds.  

NASA Astrophysics Data System (ADS)

A new method for combining satellite and surface-based cloud observations into a self-consistent three-dimensional field is presented. This method derives the probabilities of the cloud states, which are most consistent with all of the observations and assumptions concerning the nature and relative uncertainties of the observations. It is applied to a three-layer atmosphere using monthly satellite- and surface-based cloud observations. The reconstructions of the observed fields usually lead to modifications of the surface-observed low cloud amount of less than 0.008 fractional cloud cover. Over the ocean the satellite-view low cloud amounts are usually decreased by between 0.06 and 0.12 for most of the middle latitudes and southeastern tropical Pacific. Over land the adjustments in the satellite low cloud amounts are generally smaller. The method leads to increases in satellite high cover of between 0.03 and 0.09 over most regions, and increases in middle cloud cover of up to around 0.03 over the subtropical oceans. Comparisons between derived total cloud cover and that calculated with the commonly used random and mixed overlap assumptions suggest that the mixed assumption generally better fits the results. On the whole there is overall fairly good agreement between the percent low cloud relative to total cloud cover in the reconstructed observations and a global climate model, but the model has a far larger percentage of high clouds nearly everywhere, especially in the tropical convective regions and over the Indian subcontinent.

Weare, Bryan C.

1999-03-01

311

OBSERVED POLARIZATION OF BROWN DWARFS SUGGESTS LOW SURFACE GRAVITY  

SciTech Connect

Light scattering by atmospheric dust particles is responsible for the polarization observed in some L dwarfs. Whether this polarization arises from an inhomogeneous distribution of dust across the disk or an oblate shape induced by rotation remains unclear. Here, we argue that the latter case is plausible and, for many L dwarfs, the more likely one. Furthermore, evolutionary models of mature field L dwarfs predict surface gravities ranging from about 200 to 2500 m s{sup -2} (corresponding to masses of {approx}15-70 M {sub Jupiter}). Yet comparison of observed spectra to available synthetic spectra often does not permit more precise determination of the surface gravity of individual field L dwarfs, leading to important uncertainties in their properties. Since rotationally induced non-sphericity, which gives rise to non-zero disk-integrated polarization, is more pronounced at lower gravities, polarization is a promising low gravity indicator. Here, we combine a rigorous multiple scattering analysis with a self-consistent cloudy atmospheric model and observationally inferred rotational velocities and find that the observed optical polarization can be explained if the surface gravity of the polarized objects is about 300 m s{sup -2} or less, potentially providing a new method for constraining L dwarf masses.

Sengupta, Sujan [Indian Institute of Astrophysics, Koramangala 2nd Block, Bangalore 560 034 (India); Marley, Mark S., E-mail: sujan@iiap.res.i, E-mail: Mark.S.Marley@NASA.go [NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States)

2010-10-20

312

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.

Passow, Michael

313

Determination of Precipitable Water Vapors by Combining Ground-based GPS Measurements and Automatic Weather Station Observations  

NASA Astrophysics Data System (ADS)

Recently, the Korea Meteorological Administration (KMA) has initiated a research project to obtain near-real-time estimates of precipitable water vapor (PWV) based on ground-based GPS measurements. About 80 GPS permanent stations are being utilized to calculate GPS PWV. Currently, however, only 10 GPS permanent stations have their own weather sensors connected to the GPS receiver. To overcome this limitation, interpolation of pressures and temperatures from nearby Automatic Weather Station (AWS) is needed for the GPS station without a meteorological sensor. There are approximately 500 operational AWSs in Korea. In this study, we tried the geostatistical interpolation method called Kriging and Reverse Sea Level Correction (RSLC) as interpolation strategies. As a result, the root-mean-square error (RMSE) of the Kriging interpolation were 1.3 hPa and 1.8 °C. On the other hand, the RMSE of the RSLC were 0.2 hPa and 1.2 °C. Therefore, the RSLC was chosen as our interpolation method. For the geoid model for RSLC interpolation, EGM2008 geoid model used. The RMS accuracy of GPS PWV from interpolated meteorological data was about 0.5 mm. We also found that differences of GPS PWVs and pressures have an inverse correlation of -0.88.

Kim, D.; Won, J.; Kim, H.; Kim, K.; Park, K.

2010-12-01

314

Neutron monitor observations of cosmic rays as a tool for space weather monitoring -the European NMDB database  

NASA Astrophysics Data System (ADS)

European operators of neutron monitors created the Real time database for high-resolution neutron monitor measurements(NMDB), with support by the 7th Framework Programme of the European Commission. NMDB hosts data on cosmic rays in the GeV range from European and some non-European neutron monitor stations, with time resolution as high as 1 min. Most stations update their data in real time, so that they can be used for space weather applications. Besides neutron monitor count rates the database offers a variety of user-friendly applications ranging from the representation and retrieval of cosmic ray data over solar energetic particle alerts to the calculation of ionisation rates in the atmosphere and effective radiation dose rates at aircraft altitudes. Access to the data and data products is provided through a web interface. Direct access can be granted upon request. This contribution will present the data and data products, and will illustrate their use for space weather purposes.

Klein, Karl-Ludwig; Steigies, Christian

315

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

316

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

2012-09-04

317

Observations of Ocean surface response to Hurricane Igor: A Salty Tropical Cyclone Wake observed from Space  

NASA Astrophysics Data System (ADS)

The upper ocean response to a moving hurricane is studied using satellite and in situ observations. Sea surface salinity response is emphasized using Soil Moisture and Ocean Salinity Sensor data acquired before and after the passing of Igor, a category 5 hurricane that attained wind speeds of 136 knots in September 2010. Post minus pre-hurricane satellite estimates of sea surface salinity reveal a strong surface salinity enhancement of ~1 practical salinity unit over a ~89000 km2 ocean surface area located on the right-hand side quadrant of the storm as it passed over the Amazon and Orinoco freshwater plume. The presence of this salty wake is associated with the erosion of the freshwater plume by the hurricane-induced mixing. The strong surface layer erosion as detected from space on the right-hand side storm quadrant is confirmed by in situ observation from Argo float profilers. The thermal, density and ocean color wakes are also evaluated and exhibit very consistent patterns with the sea surface salinity wake. As Igor over passed the plume on its left-hand side quadrants, the presence of a thick barrier layer below the plume inhibited mixing and significantly reduced the surface cooling in the wake of the storm, which limited the surface cooling negative feedback on Igor intensification. With this demonstrative example, we show that the new sea surface salinity measurements from space can be very useful as a complementary dataset to help predicting Tropical cyclone intensification in thick barrier layer area, such as the western tropical Atlantic.

Reul, N.; Quilfen, Y.; Chapron, B.; Vialard, J.; Vincent, E.; Tenerelli, J.; Boyer de Montégut, C.; Vandemark, D.; Lengaigne, M.

2012-04-01

318

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

319

Surface dynamics as part of the European Plate Observing System  

NASA Astrophysics Data System (ADS)

The European Plate Observing System proposal includes a "surface dynamics" part to its objectives. EPOS will create and integrate "Dedicated observatories for multidisciplinary local data acquisition (volcanoes, in-situ fault-zone monitoring experiments, geothermal and deep drilling experiments, including the application of geophysics to Earth's surface dynamics and environmental changes)". As geologists and geophysicists we have a good idea how to measure ground motions related to earth quakes, volcanoes, landslides etc. We also know that through integration of these measurements in large arrays we gain resolution and general background information that allows a much better understanding of ground motion, rates of deformation and the driving forces. How can these geophysical measurements be applied to other environmental geoscience problems? What sorts of observations might one include in EPOS? Surface dynamic processes that can be measured by geophysical techniques include permafrost changes, coastline retreat, catchment morphology, post-glacial ice rebound, groundwater variation etc.. Some of these processes are driven by factors inherent to the deep Earth (lithosphere, mantle) interaction with surface processes (erosion, climate, sea level) which control the development of topography and are the focus of the TopoEurope project an ILP and an ESF-sponsored multidisciplinary research addresses within EPOS. Others processes are driven by climate change, population dynamics and people living on and interacting with the Earth's surface and subsurface. Where should the EPOS role focus? When do these problems become global in impact? When does geological engineering become a focus for EPOS - should it? The aim of this paper is to stimulate discussion on how surface dynamics should be integrated into EPOS.

Ludden, John

2010-05-01

320

Locating potential biosignatures on Europa from surface geology observations.  

PubMed

We evaluated the astrobiological potential of the major classes of geologic units on Europa with respect to possible biosignatures preservation on the basis of surface geology observations. These observations are independent of any formational model and therefore provide an objective, though preliminary, evaluation. The assessment criteria include high mobility of material, surface concentration of non-ice components, relative youth, textural roughness, and environmental stability. Our review determined that, as feature classes, low-albedo smooth plains, smooth bands, and chaos hold the highest potential, primarily because of their relative young age, the emplacement of low-viscosity material, and indications of material exchange with the subsurface. Some lineaments and impact craters may be promising sites for closer study despite the comparatively lower astrobiological potential of their classes. This assessment will be expanded by multidisciplinary examination of the potential for habitability of specific features. PMID:14987486

Figueredo, Patricio H; Greeley, Ronald; Neuer, Susanne; Irwin, Louis; Schulze-Makuch, Dirk

2003-01-01

321

Molecular basis for solvent dependent morphologies observed on electrosprayed surfaces.  

PubMed

We study the causes of the observed tunable hydrophobicity of poly(styrene-co-perfluoroalkyl ethylacrylate) electrosprayed in THF, DMF, and THF?:?DMF (1?:?1) solvents. Under the assumption that equilibrium morphologies in the solvent significantly affect the patterns observed on electrosprayed surfaces, we use atomistic and coarse-grained simulations supported by dynamic light scattering (DLS) experiments to focus on the parameters that affect the resulting morphology of superhydrophobic electrosprayed beads. The differing equilibrium chain size distributions in these solvents examined by DLS are corroborated by chain dimensions obtained via molecular dynamics simulations. Mesoscopic morphologies monitored by dissipative particle dynamics simulations explain experimental observations; in particular, the preference of the polymer for THF over DMF in the binary mixture rationalizes the dual scale roughness driven by stable microphase separation. Drying phenomena that affect resultant dual-scale roughness are described in three stages, each interpreted by concentration dependent diffusion and surface mass transfer coefficients of the solvents. Irrespective of the presence of polar groups in the structure, a conflict between the lower-boiling point solvent adhering to the polymer and the less volatile solvent abundant in the bulk leads to perfectly hydrophobic surfaces. PMID:24056882

Ozden-Yenigun, Elif; Simsek, Eren; Menceloglu, Yusuf Ziya; Atilgan, Canan

2013-10-01

322

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

323

Effects of Weathering on Basaltic Rocks and Their Thermal Emission Spectra: Implications for Evaluating Mars Mineralogy and Weathering  

NASA Astrophysics Data System (ADS)

Thermal emission spectroscopy has provided crucial information about the mineralogical composition of the Martian surface. Portions of that surface may be chemically weathered, and it is, therefore, important that the influence of chemical weathering on thermal infrared observations be recognized and understood. To this end, we have examined a suite of weathered rocks collected from the Columbia River Basalt Group. Weathering causes distinct changes to the thermal emissivity spectra of these basalts, which will be discussed in detail by J. R. Michalski et al. (this meeting). Here, we document physical and mineralogical features of weathering rinds to understand how weathering affects infrared spectra. Chemical weathering of basalts forms microcracks, dissolves primary minerals, and produces secondary phases. In the rocks examined, the relative abundance of primary minerals is the same in the weathering rind and corresponding unweathered rock. This is true even for olivine, the least stable phase in the rocks studied. Thus, preferential dissolution is not a controlling factor in the observed spectral changes. Microcracks form by expansion and dissolution and represent <20 vol% of the weathering rinds studied. While they potentially act as blackbody cavities, they probably influence emissivity spectra more by acting as sites where secondary phases form. Because the cracks are generally a few micrometers in width, the secondary phases filling them are optically thin, which may produce nonlinearity in spectral mixing of mineral phases, complicating spectral modeling. Secondary phases are Si-Al-rich and strongly influence the Si-O stretching region of infrared spectra. Dissolution of silica from primary phases and its precipitation in microcracks are the principle factors controlling changes in emissivity spectra in weathered rocks. These changes can lead to inaccurate relative abundances of primary phases derived from deconvolution modeling of weathered rocks. Also, the secondary silicates are generally amorphous to poorly crystalline, and deconvolution modeling misinterprets these materials as silicate glasses and clay minerals. The exact effects weathering exerts on emissivity spectra and subsequent modeling results will depend on what secondary silicates form, particularly how much silica is present, which will in turn depend on the conditions of weathering. However, the basic scenario of crack formation and mineralogical redistribution of silica should hold for a wide range of weathering conditions, and similar effects are expected for weathered Martian surfaces.

Kraft, M. D.; Michalski, J. R.; Sharp, T. G.

2005-12-01

324

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

325

Seaglider observations of surface mixed layer physics and biogeochemistry  

NASA Astrophysics Data System (ADS)

The Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS) aims to develop new, physically-based parameterisations of processes that deepen and shoal the ocean surface boundary layer. As part of this project, 2 Seagliders were deployed in September 2012 at the Porcupine Abyssal Plain (PAP) site in the North Atlantic, to measure the structure and evolution of the ocean surface boundary layer over the seasonal cycle. The gliders measured temperature, salinity, dissolved oxygen, dive-averaged currents, chlorophyll fluorescence, CDOM fluorescence and PAR. We present results from the first 6 months of the Seaglider deployments, examining particular case studies of deepening/shoaling events and their impact on the biogeochemistry. Shoaling events appear to be more abrupt than deepening events. We also discuss the water masses found in the area, in particular, the occurrences of Mediterranean Water observed at a depth of approximately 800 m. As a contribution to the GROOM project, we assess the advantages and challenges of maintaining a continuous glider-based multidisciplinary observing system at the PAP site, with 2 gliders being turned around approximately every 4 months.

Damerell, Gillian; Heywood, Karen; Thompson, Andrew; Henson, Stephanie; Rumyantseva, Anya

2013-04-01

326

Rb Sr and K Ar systems of biotite in surface environments regulated by weathering processes with implications for isotopic dating and hydrological cycles of Sr isotopes  

NASA Astrophysics Data System (ADS)

Biotite is widely used for Rb-Sr and K-Ar isotopic dating and influences Sr isotope geochemistry of hydrological regimes. The isotopic system of biotite behaves diversely in response to surface weathering; i.e. the complete preservation of original Rb-Sr and K-Ar isotopic ages or dramatic reduction. In this study, we have explored the relation between the behavior of isotopic systems and complex weathering processes of biotites in the weathering profiles distributed on the Mesozoic granitoids in South Korea. In the lower parts of the profiles, biotite in the early stages of weathering was transformed into either oxidized biotite or hydrobiotite, with a mass release of 87Sr and 40Ar forced by the rapid oxidation of ferrous iron. During the transformation to oxidized biotite, 87Sr and 40Ar were preferentially released relative to Rb and K, respectively, via solid-state diffusion through the biotite lattice, resulting in a drastic reduction of original isotopic age. The reduction of Rb-Sr age was greater than that of K-Ar age because K was preferentially released over Rb whereas 87Sr and 40Ar were released proportionally to each other. However, during the transformation of biotite to hydrobiotite (i.e., to regularly interstratified biotite-vermiculite), 87Sr, Rb, 40Ar, and K were completely retained in the alternating biotite interlayer, and thus the original isotopic age can be preserved. In the upper parts of the profiles, where iron oxidation was almost completed, 87Sr, Rb, 40Ar, and K were gradually and proportionally released, with no further significant change in isotopic age during the gradual transformation of the early-formed oxidized biotite into hydrobiotite and vermiculite or during their final decomposition to kaolinite. The ratios and amounts of isotopes released from weathered biotites are dependent upon the degree of iron oxidation and the pathways of mineralogical transformation. Regional and local variations in isotopic systems affected by particular weathering processes should be considered when dating biotite or biotite-bearing rocks in weathering environments, modeling the transfer of Sr isotopes to hydrologic regimes, and tracking the provenance of sediments.

Jeong, Gi Young; Cheong, Chang-Sik; Kim, Jeongmin

2006-09-01

327

Shortwave spectral radiative forcing of cumulus clouds from surface observations  

NASA Astrophysics Data System (ADS)

The spectral changes of the shortwave total, direct and diffuse cloud radiative forcing (CRF) at surface are examined for the first time using spectrally resolved all-sky flux observations and clear-sky fluxes. The latter are computed applying a physically based approach, which accounts for the spectral changes of aerosol optical properties and surface albedo. Application of this approach to 13 summertime days with single-layer continental cumuli demonstrates: (i) the substantial contribution of the diffuse component to the total CRF, (ii) the well-defined spectral variations of total CRF in the visible spectral region, and (iii) the strong statistical relationship between spectral (500 nm) and shortwave broadband values of total CRF. Our results suggest that the framework based on the visible narrowband fluxes can provide important radiative quantities for rigorous evaluation of radiative transfer parameterizations and also can be applied for estimation of the shortwave broadband CRF.

Kassianov, E.; Barnard, J.; Berg, L. K.; Long, C. N.; Flynn, C.

2011-04-01

328

Explaining Variations in Microwave Surface Emissivity from Passive Microwave Observations  

NASA Astrophysics Data System (ADS)

The Global Precipitation Measurement (GPM) Microwave Imager (GMI) onboard the core satellite orbits at a 65 degree inclination, providing more observations over land areas whose underlying microwave surface emissivity is subject to wider variations. The emissivity at each channel is highly correlated, suggesting that characterization for one channel should not be done independently of another. Also, the surface emissivity can change very rapidly with the onset of precipitation. Principal component analysis was performed on the emissivity retrieved from a large set of global, over-land, multi-year, clear-scene A-Train observations (AMSR-E and MHS). It is shown that the 10-89 GHz emissivity spectrum can be reconstructed from the first three principal components, which in turn were estimated directly from the observed brightness temperatures. When these coefficients were applied to entire orbits of AMSR-E data, the reconstructed emissivity exceeded unity for regions associated with the presence of over-land precipitation. Examples are shown for cases that are further subsetted by the presence and amount of previous-time precipitation.

Turk, F. J.; Haddad, Z. S.; Park, K.

2011-12-01

329

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

330

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

331

Land Surface Albedo of Large Urban Agglomerations from Landsat Observations  

NASA Astrophysics Data System (ADS)

The world's urban population is expected to rise to 5 billion by the year 2030 and urban climates are expected to have a growing influence on surface energy budgets at regional-to-global scales. A key component of surface energy balance is shortwave reflectivity or albedo, which can be measured and modeled with optical satellite imagery such as Landsat. In this study, we processed Landsat ETM+ imagery of world's 20 largest urban areas as of the early 2000s. To derive robust albedo estimates for each urban area, we applied an atmospheric correction and BRDF modeling using the 6s atmospheric radiative transfer model as well as an empirically based narrow-to-broadband conversion involving ETM+ bands 2, 4, and 7. A spatial analysis of the resultant albedo images was performed using various statistical and geostatistical methods. The results reveal moderate variability of land-surface albedo values among the various urban areas with mean values for urban land surfaces ranging between 0.12 for Cairo to 0.23 for Buenos Aires. As expected, in most instances we found that the albedo of these large urban areas was less than what we observed for nearby non-urban land cover types. The absolute differences in albedo between urban areas and adjacent non-urban areas within each ETM+ scene ranged from large (0.21 for Cairo) to very small (0.02 for Shanghai). Our preliminary conclusion is that the albedo difference (or the "urban albedo effect") between urban and adjacent non-urban land surfaces was greater for cities situated in arid environments than "green" cities that are situated in mesic, temperate regions.

Fuller, D. O.; Roy, S. S.; Cohen, A.

2006-05-01

332

Decadal prediction of observed and simulated sea surface temperatures  

NASA Astrophysics Data System (ADS)

multivariate regression model derived from climate model simulations is shown to produce skillful predictions of unforced, annual mean sea surface temperature variations on multiyear time scales in observations and climate model simulations. Patterns that can be predicted with skill are identified explicitly and shown to arise from a combination of persistence and coupled interactions in the Pacific Ocean. Adding the regression model predictions to an estimate of the response to anthropogenic and natural forcing yields a prediction with higher skill than either alone, demonstrating the contribution of initial condition information to skill on multiyear time scales.

Delsole, Timothy; Jia, Liwei; Tippett, Michael K.

2013-06-01

333

The Space Weather Reanalysis  

NASA Astrophysics Data System (ADS)

The objective of this project is to generate a complete 11 year space weather representation using physically consistent data-driven space weather models. The project will create a consistent, integrated historical record of the near Earth space environment by coupling observational data from space environmental monitoring systems archived at NGDC with data-driven, physically based numerical models. The resulting product will be an enhanced look at the space environment on consistent grids, time resolution, coordinate systems and containing key fields allowing an interested user to quickly and easily incorporate the impact of the near-Earth space climate in environmentally sensitive models. Currently there are no easily accessible long term climate archives available for the space-weather environment. Just as with terrestrial weather it is crucial to understand both daily weather forecasts as well as long term climate changes, so this project will demonstrate the ability to generate a meaningful and physically derived space weather climatology. The results of this project strongly support the DOD's Environmental Scenario Generator (ESG) project. The ESG project provides tools for intellegent data mining, classification and event detection which could be applied to a historical space-weather database. The two projects together provide a suite of tools for the user interested in modeling the effect of the near-earth space environment. We will present results and methodologies developed during the first two years of effort in the project.

Kihn, E. A.; Ridley, A. J.; Zhizhin, M.

2002-12-01

334

Observations of Strong Surface Radar Ducts over the Persian Gulf.  

NASA Astrophysics Data System (ADS)

Ducting of microwave radiation is a common phenomenon over the oceans. The height and strength of the duct are controlling factors for radar propagation and must be determined accurately to assess propagation ranges. A surface evaporation duct commonly forms due to the large gradient in specific humidity just above the sea surface; a deeper surface-based or elevated duct frequently is associated with the sudden change in temperature and humidity across the boundary layer inversion.In April 1996 the U.K. Meteorological Office C-130 Hercules research aircraft took part in the U.S. Navy Ship Antisubmarine Warfare Readiness/Effectiveness Measuring exercise (SHAREM-115) in the Persian Gulf by providing meteorological support and making measurements for the study of electromagnetic and electro-optical propagation. The boundary layer structure over the Gulf is influenced strongly by the surrounding desert landmass. Warm dry air flows from the desert over the cooler waters of the Gulf. Heat loss to the surface results in the formation of a stable internal boundary layer. The layer evolves continuously along wind, eventually forming a new marine atmospheric boundary layer. The stable stratification suppresses vertical mixing, trapping moisture within the layer and leading to an increase in refractive index and the formation of a strong boundary layer duct. A surface evaporation duct coexists with the boundary layer duct.In this paper the authors present aircraft- and ship-based observations of both the surface evaporation and boundary layer ducts. A series of sawtooth aircraft profiles map the boundary layer structure and provide spatially distributed estimates of the duct depth. The boundary layer duct is found to have considerable spatial variability in both depth and strength, and to evolve along wind over distances significant to naval operations (100 km). The depth of the evaporation duct is derived from a bulk parameterization based on Monin-Obukhov similarity theory using near-surface data taken by the C-130 during low-level (30 m) flight legs and by ship-based instrumentation. Good agreement is found between the two datasets. The estimated evaporation ducts are found to be generally uniform in depth; however, localized regions of greatly increased depth are observed on one day, and a marked change in boundary layer structure resulting in merging of the surface evaporation duct with the deeper boundary layer duct was observed on another. Both of these cases occurred within exceptionally shallow boundary layers (100 m), where the mean evaporation duct depths were estimated to be between 12 and 17 m. On the remaining three days the boundary layer depth was between 200 and 300 m, and evaporation duct depths were estimated to be between 20 and 35 m, varying by just a few meters over ranges of up to 200 km.The one-way radar propagation factor is modeled for a case with a pronounced change in duct depth. The case is modeled first with a series of measured profiles to define as accurately as possible the refractivity structure of the boundary layer, then with a single profile collocated with the radar antenna and assuming homogeneity. The results reveal large errors in the propagation factor when derived from a single profile.

Brooks, Ian M.; Goroch, Andreas K.; Rogers, David P.

1999-09-01

335

Titan's Surface Composition from Cassini VIMS Solar Occultation Observations  

NASA Astrophysics Data System (ADS)

Titan's surface is obscured by a thick absorbing and scattering atmosphere, allowing direct observation of the surface within only a few spectral win-dows in the near-infrared, complicating efforts to identify and map geologi-cally important materials using remote sensing IR spectroscopy. We there-fore investigate the atmosphere's infrared transmission with direct measure-ments using Titan's occultation of the Sun as well as Titan's reflectance measured at differing illumination and observation angles observed by Cas-sini's Visual and Infrared Mapping Spectrometer (VIMS). We use two im-portant spectral windows: the 2.7-2.8-mm "double window" and the broad 5-mm window. By estimating atmospheric attenuation within these windows, we seek an empirical correction factor that can be applied to VIMS meas-urements to estimate the true surface reflectance and map inferred composi-tional variations. Applying the empirical corrections, we correct the VIMS data for the viewing geometry-dependent atmospheric effects to derive the 5-µm reflectance and 2.8/2.7-µm reflectance ratio. We then compare the cor-rected reflectances to compounds proposed to exist on Titan's surface. We propose a simple correction to VIMS Titan data to account for atmospheric attenuation and diffuse scattering in the 5-mm and 2.7-2.8 mm windows, generally applicable for airmass < 3.0. We propose a simple correction to VIMS Titan data to account for atmospheric attenuation and diffuse scatter-ing in the 5-mm and 2.7-2.8 mm windows, generally applicable for airmass < 3.0. The narrow 2.75-mm absorption feature, dividing the window into two sub-windows, present in all on-planet measurements is not present in the occultation data, and its strength is reduced at the cloud tops, suggesting the responsible molecule is concentrated in the lower troposphere or on the sur-face. Our empirical correction to Titan's surface reflectance yields properties shifted closer to water ice for the majority of the low-to-mid latitude area covered by VIMS measurements. Four compositional units are defined and mapped on Titan's surface based on the positions of data clusters in 5-mm vs. 2.8/2.7-mm scatter plots; a simple ternary mixture of H2O, hydrocarbons and CO2 might explain the reflectance properties of these surface units. The vast equatorial "dune seas" are compositionally very homogeneous, perhaps suggesting transport and mixing of particles over very large distances and/or and very consistent formation process and source material. The composi-tional branch characterizing Tui Regio and Hotei Regio is consistent with a mixture of typical Titan hydrocarbons and CO2, or possibly methane/ethane; the concentration mechanism proposed is something similar to a terrestrial playa lake evaporate deposit, based on the fact that river channels are known to feed into at least Hotei Regio.

McCord, Thomas; Hayne, Paul; Sotin, Christophe

2013-04-01

336

Gravitational radiation antennas - History, observations, and lunar surface opportunities  

NASA Astrophysics Data System (ADS)

The paper discusses the suitability of the lunar surface for observing the quadrupole modes with a long-period accelerometer as well as gravitational radiation by means of a low-frequency bar and interferometer antennas. The theoretical background of gravitational radiation antennas is described emphasizing the General theory of Relativity. One measurement method involves the use of an elastic solid such as an aluminum cylinder whose length changes as spacetime curvature changes. The second method described involves the use of a Michelson interferometer which measures fractional changes in length. Results of the measurements are given for the period during the supernova 1987A, and applications of the experimental apparatuses to lunar gravitational observations are discussed. The large cross sections of the lunar quadrupole modes make the moon a good place for the use of a long-period accelerometer.

Weber, J.

1990-03-01

337

STATISTICAL CORRELATIONS OF SURFACE WIND DATA: A COMPARISON BETWEEN A NATIONAL WEATHER SERVICE STATION AND A NEARBY AEROMETRIC MONITORING NETWORK  

EPA Science Inventory

This report presents a statistical analysis of wind data collected at a network of stations in the Southeast Ohio River Valley. The purpose of this study is to determine the extent to which wind measurements made by the National Weather Service (NWS) station at the Tri-State Airp...

338

Predicting road hazards caused by rain, freezing rain and wet surfaces and the role of weather radar  

Microsoft Academic Search

Freezing rain in the winter of 1995\\/96 has drawn attention to the severity of black-ice problems on British roads, additional to the normal increased hazards presented to drivers by any form of precipitation. Disruption to traffic was considerable on several days. Weather radar provides improved nowcasting, for both winter and summer conditions, where available real time directly to highway engineers,

Leslie Symons; Allen Perry

1997-01-01

339

Observations and modelling of winds and waves during the surface wave dynamics experiment. Report 2. Intensive observation period IOP-3, 25 February-9 March 1991. Technical report  

SciTech Connect

This report describes the compilation of observed and modelled wind, wave and current parameters during the third intensive observation period (IOP-3) from February 25 to March 9, 1991, of the Surface Wave Dynamics Experiment. The measurements include wind speed and direction, wave heights and periods, air and sea temperatures, and atmospheric pressures from four directional wave buoys, two meteorological buoys, and several routinely operated buoys from the National Data Buoy Center (NDBC). Examples of directional wave spectra obtained from two airborne radars and from a Swath ship are presented along with surface currents from airborne expendable current profilers (AXCP) and acoustic doppler current profilers (ADCP). In addition, a summary of directional wave spectra is presented for this period. The model data include examples of wind fields from six numerical weather prediction models and the corresponding wave height maps as derived from the 3G-WAM ocean wave model. Estimated surface current velocities and directions from the Fleet Numerical Oceanographic Center (FNOC) model and selected satellite images of sea surface temperature fields are also presented for this time period.

Caruso, M.J.; Graber, H.C.; Jensen, R.E.; Donelan, M.A.

1994-03-01

340

Natural Weathering Rates of Silicate Minerals  

Microsoft Academic Search

Silicates constitute more than 90% of the rocks exposed at Earth's land surface (Garrels and Mackenzie, 1971). Most primary minerals comprising these rocks are thermodynamically unstable at surface pressure\\/temperature conditions and are therefore susceptible to chemical weathering. Such weathering has long been of interest in the natural sciences. Hartt (1853) correctly attributed chemical weathering to \\

A. F. White

2003-01-01

341

Satellite-tracked drift buoy observations of the near-surface flow in the eastern Mid-Latitude North Pacific  

SciTech Connect

The surface and near-surface (30 m) currents of the eastern mid-latitude Pacific obtained from 32 satellite-tracked drifting buoys during the period June 1977 are discussed. These observations of oceanic currents are merged with and are compared to Fleet Numerical Weather Center's daily estimates of surface winds for the same period. Statistical comparisons of these data sets reveal that the drifters move systematically approximately 30/sup 0/ to the right of the surface wind at approximately 1.5% of the wind speed. This relationship between drifter movement and surface winds occurs during the entire period except for the summer months of 1976 when independent of the surface wins the buoy trajectories indicate mesoscale eddy motions with 100 km and 30 day time and space scales, respectively. Drifter lifetimes exceeded that of the 9-m diameter parachute drogues set at 30 m depth, thus enabling a comparison of the currents derived from the drifter motions at the surface and 30 m. These comparisons reveal no systematic difference in the drifter motions with and without drogues. These results suggest a rather uniform flow in the upper 30 m during periods of steady winds. The estimates of the nature of near-surface currents obtained from the drifters differ from those predicted by Ekman's classical theory of wind-driven flow, in that there is no evidence of either a reduction in speed or change in direction of the currents over the upper 30 m.

McNallt, G.J.

1981-09-20

342

Aspects of mineral transformation during weathering of volcanic material (the microscopic and submicroscopic level)  

Microsoft Academic Search

Mineral transformation at the earth surface is a complex process. In volcanic ejecta, such transformations tend to be fairly rapid. Many weathering studies on volcanic materials have been carried out at different scales of observations, mostly using bulk samples. However, to get a proper understanding of the mechanisms of weathering of primary minerals and formation secondary minerals it is necessary

A. G. Jongmans

1994-01-01

343

Chromatic weathering of black limestone quarried in Varenna (Lake Como, Italy)  

Microsoft Academic Search

The causes of chromatic weathering in black limestone have been investigated on samples from the main quarry of Varenna (Lake Como, Italy), which provided building stones for Lombard architecture. Our studies have been carried out combing colorimetric, mineralogical, chemical, microstructural and geochemical observations. The results suggest that the chromatic weathering affecting the surfaces of black limestone is not due to

Nicoletta Marinoni; Alessandro Pavese; Angelo Riva; Fiorenza Cella; Tiziano Cerulli

2007-01-01

344

Modeling and surface observations of arsenic dispersion from a large Cu-smelter in southwestern Europe  

NASA Astrophysics Data System (ADS)

Arsenic is a toxic element for human health. Consequently, a mean annual target level for arsenic at 6 ng m-3 in PM10 was established by the European Directive 2004/107/CE to take effect January 2013. Cu-smelters can contribute to one-third of total emissions of arsenic in the atmosphere. Surface observations taken near a large Cu-smelter in the city of Huelva (Spain) show hourly arsenic concentrations in the range of 0-20 ng m-3. The arsenic peaks of 20 ng m-3 are higher than values normally observed in urban areas around Europe by a factor of 10. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model has been employed to predict arsenic emissions, transport, and dispersion from the Cu-smelter. The model utilized outputs from different meteorological models and variations in the model physics options to simulate the uncertainty in the dispersion of the arsenic plume. Modeling outputs from the physics ensemble for each meteorological model driving HYSPLIT show the same number of arsenic peaks. HYSPLIT coupled with the Weather Research and Forecasting (WRF-ARW) meteorological output predicted the right number of peaks for arsenic concentration at the observation site. The best results were obtained when the WRF simulation used both four-dimensional data assimilation and surface analysis nudging. The prediction was good in local sea breeze circulations or when the flow was dominated by the synoptic scale prevailing winds. However, the predicted peak was delayed when the transport and dispersion was under the influence of an Atlantic cyclone. The calculated concentration map suggests that the plume from the Cu-smelter can cause arsenic pollution events in the city of Huelva as well as other cities and tourist areas in southwestern Spain.

Chen, Bing; Stein, Ariel F.; Castell, Nuria; de la Rosa, Jesus D.; Sanchez de la Campa, Ana M.; Gonzalez-Castanedo, Yolanda; Draxler, Roland R.

2012-03-01

345

Does the Solar Wind Create OH on NEO Surfaces?: Observations of 433 Eros and 1036 Ganymed  

NASA Astrophysics Data System (ADS)

The discovery of water/OH in the lunar regolith (Sunshine et al., Clark, Pieters et al. 2009) overturned years of conventional wisdom. The origin of this lunar water/OH is thought to be via interactions between the solar wind and lunar regolith, a form of space weathering/maturation processes. It was recognized by Sunshine et al. (and earlier proposed by Starukhina 2001) that these processes should also be occurring on asteroidal surfaces. Hydroxylated minerals have been found on many objects though most are associated with the carbonaceous chondrite meteorites (Rivkin et al. 2003). Those meteorites can contain water/OH bound into their minerals, and it would be difficult to disentangle solar wind-created water/OH from native asteroidal material. However, there are other asteroids more suitable for comparison with the lunar regolith than these carbonaceous asteroids. In particular, two large S-class NEOs, 1036 Ganymed and 433 Eros, made good apparitions in 2011-2012 and are excellent targets for several reasons: These specific asteroids, based on their mineralogies and meteorite analogs, are not expected to have 3- ?m bands from native material. Their solar distances vary from 1.1-1.8 AU while they are bright enough to observe and their phase angles also cover a wide range, but they do not exactly vary together allowing them to be disentangled. They provide an opportunity for observations over a long span, providing constraints on how solar wind could create water on surfaces in conditions similar to lunar conditions. The varying conditions experienced by the NEOs will allow any band variation to be characterized. Alternately, if there is no band or no variation, that will provide constraints that modeling and theory of the lunar water must explain. We will present our 3-?m spectral observations of 1036 Ganymed and 433 Eros and discuss our results. This work funded by NSF Planetary Astronomy

Rivkin, Andrew S.; Howell, E. S.; Emery, J. P.; Sunshine, J. M.

2012-10-01

346

Weather One  

NSDL National Science Digital Library

This website contains summaries and lessons about various aspects of weather. This includes the seasons, types of clouds, air, winds, global warming, hurricanes, tornadoes and lightning. Worksheets are provided to accompany the lesson themes.

Friend, Duane

347

Space Weather  

NASA Astrophysics Data System (ADS)

Following James Van Allen's discovery of Earth's radiation belts (1958), it was immediately recognized that the space environment would be hostile to the communications satellites that had been envision by Arthur Clark (1945) and John Pierce (1955). Van Allen's discovery set off a burst of "space weather" research and engineering that continues to today, paralleling "space weather" research that had, prior to 1958, been directed toward understanding environment effects on cable and early wireless communications, electric power distribution, and pipelines. Van Allen's discovery also meant that the flight of humans above the sensible atmosphere would be fraught with more peril than mere weightlessness. This Van Allen lecture will discuss the space weather considerations that arose from Van Allen's discovery as well as space weather effects that occur from numerous other physical processes in the complex sun-heliosphere-magnetosphere environmental system.

Lanzerotti, L. J.

2005-05-01

348

Basalt weathering across scales  

NASA Astrophysics Data System (ADS)

Weathering of silicate minerals impacts many geological and ecological processes. For example, the weathering of basalt contributes significantly to consumption of atmospheric carbon dioxide (CO 2) and must be included in global calculations of such consumption over geological timeframes. Here we compare weathering advance rates for basalt ( wD?), where D and ? indicate the scale at which the rate is determined and surface area measured, respectively, from the laboratory to the watershed scales. Data collected at the laboratory, weathering rind, soil profile and watershed scales show that weathering advance rate of basalt is a fractal property that can be described by a fractal dimension ( dr ? 2.3). By combining the fractal description of rates with an Arrhenius relationship for basalt weathering, we derive the following equation to predict weathering advance rates at any spatial scale from weathering advance rates measured at the BET scale: wD?=k(e. Here, k0 is the pre-exponential factor (1.29 × 10 7 mm 3 mm - 2 yr - 1 ), Ea is the activation energy (70 kj mol - 1 ), and a is a spatial constant related to the scale of measurement of BET surface area (10 - 7 mm). The term, (, is the roughness. The roughness fractal dimension can be conceptualized as a factor related to both the thickness of the reaction front and the specific surface area within the reaction front. However, the above equation can also be written in terms of a surface fractal dimension and the hypothetical average grain radius. These fractal dimensions provide insight into reaction front geometry and should vary with lithology. Once the surface area discrepancy has been accounted for using this method, we find a one to two order of magnitude range in weathering advance rates measured at any scale or temperature that can be attributed to factors such as changes in erosional regime, parent lithology, mechanism, climate, composition of reacting fluid, and biological activity. Our scaled equation, when used to predict global basalt CO 2 consumption based upon global lithologic maps, yields an uptake flux (1.75 × 1013 mol CO 2 yr - 1 ) within the predicted error of fluxes estimated based upon riverine measurements.

Navarre-Sitchler, Alexis; Brantley, Susan

2007-09-01

349

Gravestone Weathering  

NSDL National Science Digital Library

In this activity (located on pages 9-14 of PDF), learners visit a cemetery to examine the distinguishing characteristics of rock weathering. After researching stone weathering and acid rain, learners apply their knowledge to collect data related to chemical decomposition and physical disintegration at a cemetery site. This detailed lesson guide includes tips for educators, pre/post activity suggestions, hands-outs, and background information.

Wiberg, Leanne; History, National M.

2000-01-01

350

Titan's Exotic Weather  

NASA Astrophysics Data System (ADS)

Images of Titan, taken during the joint NASA and European Space Agency Cassini-Huygens mission, invoke a feeling of familiarity: washes wind downhill to damp lakebeds; massive cumuli form and quickly dissipate, suggestive of rain; and dark oval regions resemble lakes. These features arise from Titan's unique similarity with Earth: both cycle liquid between their surfaces and atmospheres, but in Titan's cool atmosphere it is methane that exists as a gas, liquid, and ice. While Titan enticingly resembles Earth, its atmosphere is 10 times thicker, so that its radiative time constant near the surface exceeds a Titan year, and prohibits large thermal gradients and seasonal surface temperature variations exceeding 3K. Titan also lacks oceans - central to Earth's climate - and instead stores much of its condensible in its atmosphere. As a result, Titan's weather differs remarkably from Earth's. Evidence for this difference appears in the location of Titan's large clouds, which frequent a narrow band at 40S latitude and a region within 30 latitude of the S. Pole. Ground-based and Cassini observations, combined with thermodynamic considerations, indicate that we are seeing large convective cloud systems. Detailed cloud models and general circulation models further suggest that these are severe rain storms, which will migrate with the change in season. Outside these migrating "gypsy" cloud bands, the atmosphere appears to be calm, humid and thus frequented by thin stratiform clouds. An intriguingly alien environment is predicted. Yet, the combined effects of Titan's patchy wet surface, atmospheric tides, possible ice volcanoes, and detailed seasonal variations remain unclear as we have witnessed only one season so far. This talk will review observations of Titan's lower atmosphere and modeling efforts to explain the observations, and explore the questions that still elude us.

Griffith, Caitlin A.

2006-09-01

351

Mineralogical constraints on the high-silica martian surface component observed by TES  

NASA Astrophysics Data System (ADS)

The Thermal Emission Spectrometer (TES) has observed a high-silica material in the dark regions of Mars that is spectrally similar to obsidian glass and may have a volcanic origin. An alternate interpretation is that the spectrally amorphous material consists of clay minerals or some other secondary material, formed by chemical alteration of surface rocks. The regions where this material is observed (e.g., Acidalia Planitia) have relatively high spectral contrast, suggesting that the high-silica material exists as coarse particulates, indurated soils or cements, within rocks, or as indurated coatings on rock surfaces. The geologic interpretation of this spectral result has major implications for understanding magmatic evolution and weathering processes on Mars. One of the complications in interpreting spectral observations of glasses and clay minerals is that both are structurally and compositionally complex. In this study, we perform a detailed spectroscopic analysis of indurated smectite clay minerals and relate their thermal emission spectral features to structural and crystal chemical properties. We examine the spectral similarities and differences between smectite clay minerals and obsidian glass from a structural-chemical perspective, and make further mineralogical interpretations from previous TES results. The results suggest that neither smectite clays nor any clay mineral with similar structural and chemical properties can adequately explain TES observations of high-silica materials in some martian dark regions. If the spectrally amorphous materials observed by TES do represent an alteration product, then these materials are likely to be poorly crystalline aluminosilicates. While all clay minerals have Si/O ratios ?0.4, the position of the emissivity minimum at Mars suggests a Si/O ratio of 0.4-0.5. The spectral observation could be explained by the existence of a silica-rich alteration product, such as Al- or Fe-bearing opal, an intimate physical mixture of relatively pure silica and other aluminosilicates (such as clay minerals or clay precursors), or certain zeolites. The chemical alteration of basaltic rocks on Mars to phyllosilicate-poor, silica-rich alteration products provides a geologically reasonable and consistent explanation for the global TES surface mineralogical results.

Michalski, Joseph R.; Kraft, Michael D.; Sharp, Thomas G.; Williams, Lynda B.; Christensen, Philip R.

2005-03-01

352

Weather and The Seasons  

NSDL National Science Digital Library

This project will allow students to see the different weather conditions that are apart of the different seasons. It will also help students to identify the characterisitics that go along with each of the different seasons, For example, what weather conditions are present in each season and how we dress for each season. With a partner watch the video: Observing Clouds On piece of paper write your answers to the following questions: 1). What types of changes in the clouds did you observe? 2). What do you think caused the changes in the clouds? (Ex: teperature, morning to night, etc) Next, with your partner, please watch the second video: Observing Precipitation On ...

Maxwell, Ms.

2012-02-07

353

Land Surface Temperature product validation using NOAA's surface climate observation networks - Scaling methodology for the Visible Infrared Imager Radiometer Suite (VIIRS)  

NASA Astrophysics Data System (ADS)

The Land Surface Temperature (LST) product from the Visible Infrared Imager Radiometer Suite (VIIRS) will provide key information for estimating Earth surface energy and water fluxes, improving weather forecasting at high spatial and temporal resolutions, and monitoring climate change. The main challenges in estimating LST from VIIRS and similar sensors (e.g., AVHRR, MODIS, AATSR) are the need to correct for surface emissivity and atmospheric water vapor attenuation, and the difficulty in quantifying LST product accuracy due to the lack of comparable in situ measurements. This work presents a new methodology that combines in situ observations with fine-scale surface modeling to allow routine quantitative assessment of VIIRS LST products and a physically-based framework for testing and improving the retrieval algorithm. The validation scheme uses NOAA's surface observations (surface and meteorological) collected by the US Climate Reference Network (CRN) and the Surface Radiation Budget Network (SURFRAD). The scaling methodology consists of the merging of information collected at different spatial resolutions and the SEtHyS land surface model to fully characterize the satellite products, i.e. measurements from ground stations to satellites platforms at high and moderate resolutions. Based on ground stations deployed over the continental United States, it has the capability to explore scaling issues over terrestrial surfaces spanning a large range of climate regimes and land cover types, including forests and mixed vegetated areas. The approach can be applied to ground stations worldwide. The project was initiated under NPOESS/JPSS program, and it is tested and proven here with NASA/MODIS data. The primary goal is to establish, in near real time, the accuracy of the LST product derived from VIIRS over a selection of field validation sites for the VIIRS algorithm working group and the science-user community.

Guillevic, P. C.; Privette, J. L.; Coudert, B.; Davis, E.; Meyers, T. P.; Palecki, M. A.; Augustine, J. A.; Ottle, C.

2011-12-01

354

National Weather Service: Weather Education  

NSDL National Science Digital Library

The National Weather Service's Office of Climate, Water, and Weather Services has a strong outreach component. This "Education" page offers a range of materials for educators and young people which includes lesson plans, brochures, satellite image collections and career information for the fields of meteorology and climatology. The site doesn't have a search engine, but visitors can scroll through eight topical sections, including "Classroom Materials", "Careers in Weather", and "Graphics, Photos, Images". Science teachers won't want to miss the "Classroom Materials", as they can find materials on the "One Sky, Many Voices" project designed to bring together meteorology projects from around the United States together in a collaborative learning environment. Moving on, the "Graphics, Photos, Images" area contains a range of lightning photos and satellite images organized into categories like "Ocean Events", "Severe Weather", and "Tropical Cyclones".

355

Joint inversion of receiver function and surface wave dispersion observations  

NASA Astrophysics Data System (ADS)

We implement a method to invert jointly teleseismic P-wave receiver functions and surface wave group and phase velocities for a mutually consistent estimate of earth structure. Receiver functions are primarily sensitive to shear wave velocity contrasts and vertical traveltimes, and surface wave dispersion measurements are sensitive to vertical shear wave velocity averages. Their combination may bridge resolution gaps associated with each individual data set. We formulate a linearized shear velocity inversion that is solved using a damped least-squares scheme that incorporates a priori smoothness constraints for velocities in adjacent layers. The data sets are equalized for the number of data points and physical units in the inversion process. The combination of information produces a relatively simple model with a minimal number of sharp velocity contrasts. We illustrate the approach using noise-free and realistic noise simulations and conclude with an inversion of observations from the Saudi Arabian Shield. Inversion results for station SODA, located in the Arabian Shield, include a crust with a sharp gradient near the surface (shear velocity changing from 1.8 to 3.5kms-1 in 3km) underlain by a 5-km-thick layer with a shear velocity of 3.5kms-1 and a 27-km-thick layer with a shear velocity of 3.8kms-1, and an upper mantle with an average shear velocity of 4.7kms-1. The crust-mantle transition has a significant gradient, with velocity values varying from 3.8 to 4.7kms-1 between 35 and 40km depth. Our results are compatible with independent inversions for crustal structure using refraction data.

Julià, J.; Ammon, C. J.; Herrmann, R. B.; Correig, A. M.

2000-10-01

356

Groundbased near-IR observations of the surface of Venus  

NASA Astrophysics Data System (ADS)

We present images of the nightside of Venus taken in the near-infrared windows at 1.0, 1.1, 1.18, 1.28, 1.31, and 2.3 microns with the new infrared camera/spectrometer IRIS on the Anglo-Australian Telescope. These data were taken in spectral-mapping mode. This technique involves scanning the telescope perpendicular to the slit, while collecting spectra at successive slit positions across the planet. We produce data cubes with one spectral and two spatial dimensions. Images can be extracted over any wavelength regions. Each image has square pixels of 0.8 inch resolution. We reduced the scattered light from the sunlit crescent in images extracted from each window by subtracting images taken on either side of the window, where the Venus atmosphere is opaque. Unlike the short wavelength windows, which reveal thermal contrasts that originate primarily from the surface and deep atmosphere, the emission in the 2.3 microns window is produced at much higher altitudes (30-40 km). Emission contrasts seen near 2.3 microns are associated with horizontal variations in the cloud optical depths, and have rotation periods of about six days. We detect large contrasts in infrared emission (20-40 percent) across the disc of Venus in the 1.0-, 1.1-, 1.18-, 1.28-, and 1.31-micron images. Contrasts at these wavelengths may be due to a combination of variations in the optical depths of the overlying sulfuric acid clouds and differences in surface emission. Comparison with the 2.3-micron images show that the patterns seen in the 1.28- and 1.31-micron windows are consistent with cloud optical depth variations alone and require no contribution from the surface. However, images at 1.0, 1.1, and 1.8 microns from July 1991 show a dark feature having a contrast that increases with decreasing wavelength. This behavior is contrary to that expected of cloud absorption. Images taken on three successive days in October show another dark feature that is stationary with respect to the surface. These regions of lower emission correspond closely to the high-altitude surface regions of Beta Regio and Aphrodite Terra. The images can potentially reveal the near-infrared emissiveity of the surface of Venus, thereby complementing Magellan radar reflectivity and ground based radio emissivity measurements. The contrast ratio between highlands and plains is much smaller than would be expected for blackbody radiation from the surface along. observed topographically induced contrasts. &The additional radiation from the atmosphere reduces the contrast, and further modification would be expected if terrain at different altitudes has different emissivities. A fit to our data therefore requires, and may constrain, a model of the lowest scale height of the atmosphere.

Meadows, V. S.; Crisp, D.; Allen, D. A.

357

THEMIS Observations and TES Surface Compositions of Low-Albedo Intracrater Materials and Wind Streaks in Western Arabia Terra  

NASA Astrophysics Data System (ADS)

High-resolution thermal infrared images (100m/pixel) from the Mars Odyssey Thermal Emission Imaging System (THEMIS) are used for thermophysical analyses of low-albedo intracrater materials and wind streaks in Western Arabia Terra and comparisons with Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) derived surface compositions. Atmospherically corrected thermal emissivity data from TES have been used to identify two global-scale spectral surface units. The Surface Type 1 end-member is interpreted as largely unweathered basalt while the Surface Type 2 end-member has been interpreted as andesite and/or partly weathered basalt. Deconvolved TES spectra of low-albedo intracrater materials reveal both Surface Type 1 and 2 compositions within individual craters. Surface Type 1 compositions form a central core in dark features on crater floors while Surface Type 2 compositions form a surrounding arc on the dark downwind sides of crater walls. The transition between these compositions appears to occur near the floor-wall interface and is correlated with a transition from high-thermal inertia dune materials to low thermal inertia dune-free materials. Surface Type 1 and 2 compositions are also observed in adjacent low albedo wind streaks; however, a mixing trend is not as evident as within the impact craters. THEMIS day/IR observations of low-albedo intracrater materials appear to show relatively lower average temperatures for Surface Type 1 compared to Surface Type 2 while THEMIS night/IR observations appear to reveal higher average temperatures for Surface Type 1 compared to Surface Type 2. There does not appear to be a discernable temperature trend for surface materials in adjacent low-albedo wind streaks. Temperature variations observed in THEMIS images can be produced by a combination of topographic (solar heating) and thermophysical (thermal inertia and albedo) effects; however, combining multiple datasets can minimize uncertainties. The transition from Surface Type 1 to Surface Type 2 intracrater materials is interpreted to reflect decreasing particle sizes controlled by mineralogic differences between an unweathered basalt component and an andesite/altered basalt component. Relatively coarse dune materials are cool (dark) during the day while finer dune-free materials are warmer (bright). Intracrater floor materials are interpreted as eolian sediment blown into craters while wall materials are interpreted as either eolian sediment sorted by particle size, or eroded material from in-place crater wall lithologies.

Wyatt, M. B.; McSween, H. Y.; Christensen, P. R.

2002-12-01

358

Weather Specialist (AFSC 25120).  

ERIC Educational Resources Information Center

This correspondence course is designed for self-study to help military personnel to attain the rating of weather specialist. The course is organized in three volumes. The first volume, containing seven chapters, covers background knowledge, meteorology, and climatology. In the second volume, which also contains seven chapters, surface

Air Univ., Gunter AFS, Ala. Extension Course Inst.

359

Intercomparison of Near-Surface Temperature and Precipitation Extremes in AMIP-2 Simulations, Reanalyses, and Observations.  

NASA Astrophysics Data System (ADS)

The extremes of near-surface temperature and 24-h and 5-day mean precipitation rates are examined in simulations performed with atmospheric general circulation models (AGCMs) participating in the second phase of the Atmospheric Model Intercomparison Project (AMIP-2). The extremes are evaluated in terms of 20-yr return values of annual extremes. The model results are validated against the European Centre for Medium-Range Weather Forecasts and National Centers for Environmental Prediction reanalyses and station data. Precipitation extremes are also validated against the pentad dataset of the Global Precipitation Climatology Project, which is a blend of rain gauge observations, satellite data, and model output.On the whole, the AGCMs appear to simulate temperature extremes reasonably well. Model disagreements are larger for cold extremes than for warm extremes, particularly in wet and cloudy regions, and over sea ice and snow-covered areas. Many models exhibit an exaggerated clustering behavior for temperatures near the freezing point of water. Precipitation extremes are less reliably reproduced by the models and reanalyses. The largest disagreements are found in the Tropics where the parameterizations of deep convection affect the simulated daily precipitation extremes.

Kharin, Viatcheslav V.; Zwiers, Francis W.; Zhang, Xuebin

2005-12-01

360

History of Martian Surface Changes Observed by Mars Global Surveyor  

NASA Astrophysics Data System (ADS)

The changing appearance of Mars has fascinated observers for centuries, yet much is still unknown about the winds and sediments that alter the albedo of vast areas of the planet’s surface. A variety of aeolian processes contribute to the deposition and erosion of dust on Mars, with distinct causes and timescales that vary with season and location. Over decadal timescales, these processes act to alter the planetary albedo distribution enough to significantly impact the climate and global circulation of winds on Mars (Geissler, JGR 110, E02001, 2005; Fenton et al., Nature 446, 646, 2007). We are documenting the extent and frequency of Martian surface changes by analyzing the rich record of observations made by the Mars Global Surveyor mission. We are currently completing a time-series of global mosaics produced from wide angle MOC images showing in detail how the planet’s surface changed in appearance between early 1999 and late 2006, a period of 4 Martian years. The MOC mosaics reveal a surprising range of temporal behavior among variable features in different regions of Mars. Episodic dust deposition followed by episodic clearing can be seen in Syrtis Major. Gradual erosion by persistent seasonal winds can be seen in many equatorial areas such as southern Alcyonius. Gradual erosion by dust-devils is prevalent at higher latitudes and notably in Nilosyrtis, where the albedo boundary dividing the high albedo tropics from the dark terrain to the north is slowly advancing southwards onto brighter terrain. Solis Planum, a high plateau south of the Valles Marineris, changes on a nearly continuous basis. Many of the moving albedo boundaries (such as those at Oxia Palus and the Southern tropical dark band) display high albedo margins that may be aprons of dust swept away by the advancing erosion. The data also show clear evidence for dust deposition onto already dust-covered regions, a phenomenon that was suspected but not demonstrated by Geissler (2005). The final MOC images show significant brightening in Vastitas Borealis, continuing a trend that may have begun in the 1980s.

Geissler, P. E.; Enga, M.; Mukherjee, P.

2009-12-01

361

Ecosystem behavior at Bermuda Station [open quotes]S[close quotes] and ocean weather station [open quotes]India[close quotes]: A general circulation model and observational analysis  

SciTech Connect

One important theme of modern biological oceanography has been the attempt to develop models of how the marine ecosystem responds to variations in the physical forcing functions such as solar radiation and the wind field. The authors have addressed the problem by embedding simple ecosystem models into a seasonally forced three-dimensional general circulation model of the North Atlantic ocean. In this paper first, some of the underlying biological assumptions of the ecosystem model are presented, followed by an analysis of how well the model predicts the seasonal cycle of the biological variables at Bermuda Station s' and Ocean Weather Station India. The model gives a good overall fit to the observations but does not faithfully model the whole seasonal ecosystem model. 57 refs., 25 figs., 5 tabs.

Fasham, M.J.R. (Natural Environment Research Council, Southampton (United Kingdom)); Sarmiento, J.L.; Slater, R.D. (Princeton Univ., NJ (United States)); Ducklow, H.W. (Univ. of Maryland Center for Environmental and Estuarine Sciences, Cambridge, MD (United States)); Williams, R. (Plymouth Marine Lab. (United Kingdom))

1993-06-01

362

How to Constrain Crustal Pore Pressure From Surface Seismic Observations  

NASA Astrophysics Data System (ADS)

The pore pressure in deeper portions of the crust is a critical quantity for understanding the mechanical behaviour of the crust. Here we propose a new technique for estimating pore pressure from remote observations made at the surface. The technique is based on the measurement of temporal variations of seismic velocities ? v associated with (known) tidal stress changes ?? '. The sensitivity ? v/?? ' which is known from lab studies depends primarily on effective stress ? '= ? -p. Different materials tend to have similar ? v/ ?? '. This suggests that we can use the lab-measured ? v/ ?? ' curve to extract the effective stress from observed sensitivities ? v/ ?? ' of velocity with respect to tidal stress. This is confirmed by comparison with measurements from the KTB borehole. We furthermore obtain the pore pressure p. Seismic velocity variations due to Earth's tides have recently been observed with unprecedented clarity in Japan (Yamamura et al., 2002), using repeated artificial signals near the surface. The tidal signal is apparent in the time-domain (relative size 10-3), and the spectral domain showed the major tidal peaks (O_1, K_1, M_2, and S_2). To constrain sensitivities at deeper levels of the crust, we can use regional waves that propagate over distances of hundreds of kilometers and are generated by certain large machines that run synchronously with the power network (Bokelmann and Baisch, 1999). We used them to obtain upper bounds on temporal velocity changes in Central Europe (Baisch and Bokelmann, 1999; Baisch, 2000, PhD-thesis). This allows us to constrain the pore pressure p in deeper levels of the crust, and it suggests that pore pressure can not be much larger than hydrostatic in Central Europe, or more precisely in Southeastern Germany which includes the region of the KTB. This is consistent with the earlier, independent measurement of approximately hydrostatic pore pressure in the KTB borehole. The technique is rather inexpensive, and should have interesting applications in tectonic areas, and especially within fault zones, where the effect of pore pressure is likely to be important. In principle, we can track changes of pore pressure with time, and thus monitor the state of an earthquake fault remotely.

Bokelmann, G.; Nur, A.; Zimmer, M.; Beroza, G.; Zoback, M. D.; Baisch, S.

2003-04-01

363

Comments on “Observation of a monthly variation in global surface temperature data”  

Microsoft Academic Search

Besl, (1994) (hereafter B94)examined European Cen- tre for Medium-Range Weather Forecasts (ECMWF) global surface temperature data for the years 1986-1991 and, after derrending the data and filtering out the sea- sonal cycle, found a small monthly oscillation of am- plitude around 0.2 K. The oscillation is larger in polar areas than in the tropics, and the northern hemisphere (Nit) and

Pedro Viterbo; Anthony Hollingsworth

1996-01-01

364

Space weather in Japan  

NASA Astrophysics Data System (ADS)

In Japan, Communications Research Laboratory engages in operational space environment information service as National Forecasting Center and Regional Warning Center of ISES. Data of local observation and data collected via internet from domestic and foreign institute are used for daily operational forecast. Fundamental research on space weather issue has been carried out at several institutes and university, including STE Laboratory and NASDA. In this presentation, overview of current space weather forecast operation and system for information outreach in Japan will be presented. Current and future observation program from ground-base and space will be also briefly reviewed.

Akioka, M.

365

Space weather in Japan  

NASA Astrophysics Data System (ADS)

In Japan, Communications Research Laboratory engages in operational space environment information services as National Forecasting Center and Regional Warning Center of ISES. Data from local observations and data collected via internet from domestic and foreign institutes are used for the daily operational forecast. Fundamental research on space weather issues has been carried out at several institutes and universities, including STE Laboratory and NASDA. In this presentation, an overview of current space weather forecast operations and a system for information outreach in Japan will be presented. Current and future observation programs from ground-base and space will be also briefly reviewed.

Akioka, M.; Ishibashi, H.; Kikuchi, T.; Sagawa, E.; Nagatsuma, T.

366

Surface observations for monitoring urban fossil fuel CO2 emissions: Minimum site location requirements for the Los Angeles megacity  

NASA Astrophysics Data System (ADS)

The contemporary global carbon cycle is dominated by perturbations from anthropogenic CO2 emissions. One approach to identify, quantify, and monitor anthropogenic emissions is to focus on intensely emitting urban areas. In this study, we compare the ability of different CO2 observing systems to constrain anthropogenic flux estimates in the Los Angeles megacity. We consider different observing system configurations based on existing observations and realistic near-term extensions of the current ad hoc network. We use a high-resolution regional model (Stochastic Time-Inverted Lagrangian Transport-Weather Research and Forecasting) to simulate different observations and observational network designs within and downwind of the Los Angeles (LA) basin. A Bayesian inverse method is employed to quantify the relative ability of each network to improve constraints on flux estimates. Ground-based column CO2 observations provide useful complementary information to surface observations due to lower sensitivity to localized dynamics, but column CO2 observations from a single site do not appear to provide sensitivity to emissions from the entire LA megacity. Surface observations from remote, downwind sites contain weak, sporadic urban signals and are complicated by other source/sink impacts, limiting their usefulness for quantifying urban fluxes in LA. We find a network of eight optimally located in-city surface observation sites provides the minimum sampling required for accurate monitoring of CO2 emissions in LA, and present a recommended baseline network design. We estimate that this network can distinguish fluxes on 8 week time scales and 10 km spatial scales to within ~12 g C m-2 d-1 (~10% of average peak fossil CO2 flux in the LA domain).

Kort, Eric A.; Angevine, Wayne M.; Duren, Riley; Miller, Charles E.

2013-02-01

367

The Weather Doctor  

NSDL National Science Digital Library

Published by Spectrum Educational Enterprises, The Weather Doctor Web site is maintained by meteorologist Keith Heidorn. Visitors to the site will find everything from the joys of weather watching, to making rain, to weather history, to much more. Coming from someone who clearly enjoys what they do, this site explores unique aspects of weather including weather people, weather history, and weather and arts.

Heidorn, Keith.

2002-01-01

368

Observed spectral properties of near-Earth objects: results for population distribution, source regions, and space weathering processes  

Microsoft Academic Search

We present new visible and near-infrared spectroscopic measurements for 252 near-Earth (NEO) and Mars-crossing (MC) objects observed from 1994 through 2002 as a complement to the Small Main-Belt Asteroid Spectroscopic Survey (SMASS, http:\\/\\/smass.mit.edu\\/). Combined with previously published SMASS results, we have an internally consistent data set of more than 400 of these objects for investigating trends related to size, orbits,

Richard P. Binzel; Andrew S. Rivkin; J. Scott Stuart; Alan W. Harris; Schelte J. Bus; Thomas H. Burbine

2004-01-01

369

Observations of Strong Surface Radar Ducts over the Persian Gulf  

Microsoft Academic Search

Ducting of microwave radiation is a common phenomenon over the oceans. The height and strength of the duct are controlling factors for radar propagation and must be determined accurately to assess propagation ranges. A surface evaporation duct commonly forms due to the large gradient in specific humidity just above the sea surface; a deeper surface-based or elevated duct frequently is

Ian M. Brooks; Andreas K. Goroch; David P. Rogers

1999-01-01

370

Surface Temperature and Soil Temperature Protocols; Observations, Partnerships, Science  

Microsoft Academic Search

As NSF funded GLOBE scientists, we have engaged students and teachers in the surface temperature and soil temperature protocols. In 2002, we started to develop the surface temperature protocol and finalized it in the spring 2005 for the GLOBE Teacher's Guide. Surface temperature is the temperature of sidewalks, parking lots, leaves, grass, bare ground, etc. as determined by the electromagnetic

K. P. Czajkowski; A. Spongberg; T. Benko; J. Witter; T. Ault; T. Peterson

2005-01-01

371

Today's Weather  

NSDL National Science Digital Library

This activity is part of Planet Diary and contains an online exploration of weather maps. Students use current maps to learn about and locate different features such as low-pressure areas and fronts. They then explore how these are related to severe storms.

372

Weather control  

Microsoft Academic Search

Weather modification, the intentional altering of atmospheric conditions to suit the purposes of humankind, has five basic forms: (1) fog dissipation; (2) rain and snow enhancement; (3) hail suppression; (4) lightning suppression; and (5) the abatement of severe storms such as hurricanes and tornadoes. The dissipation of fog and the seeding of clouds with dry ice or silver iodide to

Leepson

1980-01-01

373

Collision and Break-off : Numerical models and surface observables  

NASA Astrophysics Data System (ADS)

The process of continental collision and slab break-off has been explored by many authors using a number of different numerical models and approaches (Andrews and Billen, 2009; Gerya et al., 2004; van Hunen and Allen, 2011). One of the challenges of using numerical models to explore collision and break-off is relating model predictions to real observables from current collision zones. Part of the reason for this is that collision zones by their nature destroy a lot of potentially useful surface evidence of deep dynamics. One observable that offers the possibility for recording mantle dynamics at collision zones is topography. Here we present topography predictions from numerical models and show how these can be related to actual topography changes recoded in the sedimentary record. Both 2D and 3D numerical simulation of the closure of a small oceanic basin are presented (Bottrill et al., 2012; van Hunen and Allen, 2011). Topography is calculated from the normal stress at the surface applied to an elastic beam, to give a more realist prediction of topography by accounting for the expected elasticity of the lithosphere. Predicted model topography showed a number of interesting features on the overriding plate. The first is the formation of a basin post collision at around 300km from the suture. Our models also showed uplift postdating collision between the suture and this basin, caused by subduction of buoyant material. Once break-off has occurred we found that this uplift moved further into the overriding plate due to redistribution of stresses from the subducted plate. With our 3D numerical models we simulate a collision that propagates laterally along a subduction system. These models show that a basin forms, similar to that found in our 2D models, which propagates along the system at the same rate as collision. The apparent link between collision and basin formation leads to the investigation into the stress state in the overriding lithosphere. Preliminary results in this area indicate the stress experienced by the overriding lithosphere changes through the collision and slab break-off process. This change is stress affects the topography, but also offers another observable for understanding collision zones. We relate our numerical model to Arabia-Eurasia collision which is thought to have begun around 35 Ma (Allen and Armstrong, 2008; Vincent et al., 2007). The post collision basin predicted by our numerical model can be associated with the Miocene carbonate deposits of the Qom formation (Morley et al., 2009). These Miocene carbonate deposits are found at approximately 200-300km from the suture zone and are stratigraphically "sandwiched" between terrestrial clastic sedimentary formations. The position of these deposits shows that they are intimately related with the collision process, and that this area of the overriding plate has dipped below sea level for about 10 Myrs during the Early Miocene. Another geographic area that offers possibility for observation of topography change produced during continental collision is the Italian Apennines. Here, slab detachment is proposed to have started around 30 Ma and a tear propagated north to south along Italy (Wortel, 2000). Van der Meulen et al., (1998) observed a period of basin formation followed by uplift using the sedimentary record. Migrating depocentres were interpreted as evidence of a slab tear propagating north to south. These depocentres are located on the overriding plate with the maximum observed depression around 100 km from the suture (Ascione et al., 2012). These observed depocentres could be analogous to the depressions observed in our numerical models. Allen, M. B. and Armstrong, H. A.: Arabia-Eurasia collision and the forcing of mid-Cenozoic global cooling, Palaeogeography, Palaeoclimatology, Palaeoecology, 265(1-2), 52-58, doi:10.1016/j.palaeo.2008.04.021, 2008. Andrews, E. R. and Billen, M. I.: Rheologic controls on the dynamics of slab detachment, Tectonophysics, 464(1-4), 60-69, doi:10.1016/j.tecto.2007.09.004, 2009. Ascione, A., Ciarcia, S.,

Bottrill, Andrew; van Hunen, Jeroen; Allen, Mark

2013-04-01

374

Quantification of physical weathering rates using thermodynamics  

Microsoft Academic Search

Physical weathering plays an important role in the global rock cycle in that it breaks up primary rock, thereby increasing the surface area for chemical weathering and providing the substrate for soil formation. We use a simple, thermodynamics based approach to quantify magnitudes of weathering, their spatial variation across climatic regions and their sensitivity to climatic change. Our approach is

F. Gans; S. Arens; S. J. Schymanski; A. Kleidon

2010-01-01

375

Space weather and deep space communications  

Microsoft Academic Search

While Pioneer 11 and Galileo are two deep space missions that experienced radio communication disruptions due to space weather, the success of a mission like Solar Probe, whose goal is to fly by the Sun within a few solar radii of its surface, may depend critically on space weather. It is therefore crucial to thoroughly understand how space weather affects

Richard Woo

2007-01-01

376

Transferability of land surface model parameters using remote sensing and in situ observations.  

NASA Astrophysics Data System (ADS)

We develop predictive relationships between geographically varying catchment features and the soil parameters of a Land Surface Model (LSM) over the continental U.S.. Catchment features include State Soil Geographic (STATSGO) soil texture classes, long-term meteorological forcing data, as well as the Geospatial Attributes of Gages for Evaluating Streamflow (GAGES-II) dataset, satellite-based seasonal vegetation greenness, albedo, and a satellite-based evapotranspiration (ET) product. The study domain consists of 250 unregulated small river basins (<10000 sq. km) that span a range of hydroclimatic conditions. The LSM is the Unified Land Model (ULM), which is a merger of the Noah LSM (used in NOAA/NCEP's numerical weather prediction and climate models) and the Sacramento Soil Moisture Accounting Model (used by NWS for operational flood forecasting and seasonal streamflow forecasting). ULM was initially calibrated to streamflow and ET observations for each river basin and these calibrated parameters (predictands) were then related to the geographically varying catchment features (predictors). We first examined the inter-relationships among predictors as indicated by their spatially varying correlations. Among the predictors, we explore use the GAGES-II dataset (basin morphology, climate, topography, soils and anthropogenic disturbance factors: disturbance index, population density, and land use). We also incorporate information from satellite-ET, with the aim of evaluating applicability of the method to ungauged locations. To account for correlation among predictors and maximize their predictive strength, we use a principal components approach, from which we derive predictive relationships. Hydrologic prediction performance is evaluated using both the locally estimated (using observed stream discharge) and regional parameters.

Livneh, B.; Lettenmaier, D. P.

2012-04-01

377

SEM observations of high energy alpha-irradiated metal surfaces  

NASA Astrophysics Data System (ADS)

In this paper we present results from a study of the surface morphology of alpha-irradiated tantalum and tungsten using scanning electron microscopy (SEM). The surfaces of well polished polycrystalline Ta and W were irradiated with 32 MeV alpha-particles to a total dose of ~ 4.2 × 1017 ?/cm2. Although the irradiation conditions were same for both of these samples, the resulting surface deformations are strikingly different. A small number of unruptured blisters of irregular shape and ~ 20 to 40 ?m in size is seen on the Ta surfaces. The W surfaces are characterized by a much higher number of square shaped flakes of different sizes varying from 5 to 50 ?m. Possible reasons for the differences between the surface features seen on these samples are discussed.

Sen, P.; Nambissan, P. M. G.; Naidu, S. V.; Sharma, S. C.

1989-04-01

378

Surface Energy Fluxes on the Great Lakes Based on Satellite-Observed Surface Temperatures 1992 to 1995  

Microsoft Academic Search

Accurate estimates of surface energy exchange components are critical for understanding many physical processes of large lakes and their atmospheric environment. In this paper, the seasonal cycle of latent, sensible, and total heat flux from the surface of the Great Lakes is estimated. Lake surface temperatures derived from the NOAA\\/AVHRR satellite, along with meteorological data from surface station observations are

Brent M. Lofgren; Yongchun Zhu

2000-01-01

379

The composition of pollutted air in Moscow based on surface observations  

NASA Astrophysics Data System (ADS)

Moscow is the one of the biggest world megacities. Population, industry, transport are strong sources of air pollution. This pollution influences on the air quality in the city and in the neighbor regions due to spreading by the wind. Here we present an analysis of variations of atmospheric compounds in Moscow since 2002 until the present in its dependence on different atmospheric characteristics, particularly cyclonic and anticyclonic conditions, heat waves and anthropogenic factors. The following variables are considered: NO2, NO, CO, CO2, O3, SO2, NMHC. The monitoring site is located at Moscow State University meteorological observatory on the South-West of Moscow. All observations are provided by A.M. Obukhov Institute of Atmospheric Physics RAS. Due to these continuous measurements, the typical (ore basic) level of pollution as well as the extreme cases have been studied. The temporal variability of the atmospheric compounds, and the chemical interaction of ozone and nitrogen oxides are investigated. High concentrations of nitrogen oxides are observed throughout the year. During some months the 90th NO2 percentile exceeds 60 ppb, NO - 80 ppb. Based on surface observations, we show that extremes of pollutant concentrations correspond with anticyclonic conditions and anthropogenic processes. These often increase the impact on the weather. These situations correspond with the anomalous cold winter in 2006 and heat wave in 2002. In these periods, concentrations of air pollutions exceed MAC, but the ozone concentration usually decreases due to interaction with NOx. Only two times, ozone concentration exceeded MAC - the heat waves 2002 and 2010. Also in the study we obtain the logarithmic dependence between ozone mix ratio and NO2/NO, which can be used for prediction of the surface ozone concentrations in Moscow: [O3] = 12.22Ln([NO2]/[NO]) + 15.3 However, this equation is not possible to use in smog conditions. From 29 July to 15 August Moscow was in a dense smoke screen from the forest and peat fires. In this case, even with a small value of the ratio [NO2] / [NO] the ozone concentration exceeded 100 ppb (in the average condition maximum hourly ozone concentration for the summer is about 50-60 ppb).

Pankratova, Natalia; Elansky, Nikolai; Skorokhod, Andrey

2013-04-01

380

Surface Modification of T-Lymphocytes Observed during Rosetting  

Microsoft Academic Search

Scanning electron microscopy has been used to characterize alterations of lymphocyte surface topology that occur on contact with erythrocytes during the rosetting reaction. Molt-4 cells, a line of leukemic human lymphocytes, defined as T-cells through their ability to form rosettes with sheep erythrocytes, were used for this. Unreacted Molt-4 cells exhibit surfaces that are virtually smooth and carry few microvilli.

Peck-Sun Lin; Donald F. Hoelzl Wallach

1974-01-01

381

Weather Watchers  

NSDL National Science Digital Library

Students are introduced to some essential meteorology concepts so they more fully understand the impact of meteorological activity on air pollution control and prevention. First, they develop an understanding of the magnitude and importance of air pressure. Next, they build a simple aneroid barometer to understand how air pressure information is related to weather prediction. Then, students explore the concept of relative humidity and its connection to weather prediction. Finally, students learn about air convection currents and temperature inversions. In an associated literacy activity, students learn how scientific terms are formed using Latin and Greek roots, prefixes and suffixes, and are introduced to the role played by metaphor in language development. Note: Some of these activities can be conducted simultaneously with the air quality activity (What Color Is Your Air Today?) of Air Pollution unit, Lesson 1.

Integrated Teaching And Learning Program

382

Effect of Bacillus subtilis on Granite Weathering: A Laboratory Experiment  

NASA Astrophysics Data System (ADS)

We performed a comparative experiment to investigate how the ubiquitous soil bacterium Bacillus subtilis weathers granite and which granite-forming minerals weather more rapidly via biological processes. Batch type experiments (granite specimen in a 500 ml solution including NaCl, glucose, yeast extract and bacteria Bacillus subtilis at 27°E C) were carried out for 30 days. Granite surfaces were observed by SEM before and after the experiment. Bacillus subtilis had a strong influence on granite weathering by forming pits. There were 2.4 times as many pits and micropores were 2.3 times wider in granite exposed to Bacillus subtilis when compared with bacteria-free samples. Bacillus subtilis appear to preferentially select an optimum place to adhere to the mineral and dissolve essential elements from the mineral to live. Plagioclase was more vulnerable to bacterial weathering than biotite among the granite composing minerals.

Song, W.; Ogawa, N.; Oguchi, C. T.; Hatta, T.; Matsukura, Y.

2006-12-01

383

Weather Cycles  

NASA Astrophysics Data System (ADS)

This completely updated edition explores in detail the unresolved debate on the existence of weather cycles. It provides a different perspective on one of the most difficult questions in the current global warming debate: how much of the recent temperature rise can be attributed to natural causes? The book examines the complex analysis required to assess the evidence for cycles with a minimum of mathematics. First Edition Hb (1992): 0-521-38178-9 First Edition Pb (1995): 0-521-47869-3

Burroughs, William James

2003-12-01

384

Electrical Properties of the Venus Surface from Bistatic Radar Observations  

PubMed

A bistatic radar experiment in 1994, involving reception on Earth of a specularly reflected, linearly polarized 13-centimeter-wavelength signal transmitted from the Magellan spacecraft in orbit around Venus, has established that the surface materials viewed at low and intermediate altitudes on Venus have a relative dielectric permittivity of 4.0 ± 0.5. However, bistatic results for the Maxwell Montes highlands imply an electrically lossy surface with an imaginary dielectric permittivity of -i 100 ± 50, probably associated with a specific conductivity of about 13 mhos per meter. Candidates for highlands surface composition include ferroelectrics, a thin frost of elemental tellurium, or a plating of magnetite or pyrites. PMID:8662473

Pettengill; Ford; Simpson

1996-06-14

385

Aviation weather radar  

Microsoft Academic Search

The Federal Aviation Administration has established three ground-based weather radar programs. The terminal Doppler weather radar (TDWR) and weather system processor (WSP) provide wind shear detection capability for air traffic controllers in the terminal area. These systems also reduce weather related delays. The next generation weather radar (NEXRAD) is used by the FAA to improve safety and reduce weather related

D. H. Turnbull

1995-01-01

386

Weather Science Hotlist  

NSDL National Science Digital Library

The Franklin Institute Online offers the metadata Web site Weather Science Hotlist. The page contains dozens of links organized into ten topics that include Online Exhibits, Weather Right Now, Background Information, Severe Weather, El Nino/ La Nina, Historical Weather, Career Connections, Activities, Atmosphere, and Weather Forecasting. A great source for anyone looking for online weather information.

1969-12-31

387

Fire-induced changes in surface albedo as observed from MODIS observations  

NASA Astrophysics Data System (ADS)

An integrated assessment of the overall radiative forcing caused by fire is critical for fire and carbon management The forcing due to greenhouse gas is well known but there is a major gap in estimates of forcing due to fire-induced albedo change Our objective is to examine the temporal evolution of post-fire albedo and analyze its relationship with the vegetation succession using MODIS satellite observations We focus on two fire prone regions with very different fire regimes and vegetation succession patterns Australia tropical savanna and Alaska boreal forest We use MODIS albedo and vegetation index data from the years 2000 through 2004 from Northern Australia and interior Alaska Burned area were derived from MODIS observations in Northern Australia and burn perimeters from 1950 through 2003 were identified by using the Alaska Fire History 1950-2004 GIS Database In northern Australia the shortwave albedo decreased by anaverage of 0 024 within 16 to 32 days after fire The albedo decreased by a greater amount in grasslands than woody savannas and as the dry season progressed The albedo starts to increase within months after fire along with ash dissipation and fast vegetation regrowth in savannas In post-fire boreal forest both the vegetation succession and snow cover contributes to the temporal evolution of surface albedo After boreal fire albedo in spring March and April increases by 0 165 as compared with unburned areas and reaches its maximum at nine years since fire In summer June and July albedo shows an initial decrease of

Jin, Y.; Randerson, J.; Roy, D.; Lyons, E.; Goulden, M.

388

H I observations of giant low surface brightness galaxies  

Microsoft Academic Search

We have used the Nançay Radio Telescope to obtain new global H I data for 16 giant low surface brightness (LSB) galaxies. Our targets have optical luminosities and disk scale lengths at the high end for spiral galaxies (LB~1010 Lsun and h_r>~ 6 kpc for H0=75 km s-1 Mpc-1), but they have diffuse stellar disks, with mean disk surface brightnesses

L. D. Matthews; W. van Driel; D. Monnier-Ragaigne

2001-01-01

389

First observation of surface plasmon-coupled electrochemiluminescence  

Microsoft Academic Search

Electrochemiluminescence (ECL) is often used for high sensitivity detection. We describe a new approach to collecting the ECL signal, by coupling of the excited state of [Ru(bpy)3]2+ with the surface plasmons in a thin gold film. The energy then radiates into the substrate at a defined angle. Surface plasmon-coupled ECL promises to be useful in chemical and biological assays.

Jian Zhang; Zygmunt Gryczynski; Joseph R. Lakowicz

2004-01-01

390

Disaggregation of screen-level variables in a numerical weather prediction model with an explicit simulation of subgrid-scale land-surface heterogeneity  

NASA Astrophysics Data System (ADS)

The earth's surface is characterized by small-scale heterogeneity attributable to variability in land cover, soil characteristics and orography. In atmospheric models, this small-scale variability can be partially accounted for by the so-called mosaic approach, i.e., by computing the land-surface processes on a grid with an explicit higher horizontal resolution than the atmosphere. The mosaic approach does, however, not account for the subgrid-scale variability in the screen-level atmospheric parameters, part of which might be related to land-surface heterogeneity itself. In this study, simulations with the numerical weather prediction model COSMO are shown, employing the mosaic approach together with a spatial disaggregation of the atmospheric forcing by the screen-level variables to the subgrid-scale. The atmospheric model is run with a 2.8 km horizontal grid resolution while the land surface processes are computed on a 400-m horizontal grid. The disaggregation of the driving atmospheric variables at screen-level is achieved by a three-step statistical downscaling with rules learnt from high-resolution fully coupled COSMO simulations, where both, atmosphere and surface, were simulated on a 400-m grid. The steps encompass spline interpolation of the grid scale variables, conditional regression based on the high-resolution runs, and an optional stochastic noise generator which restores the variability of the downscaled variables. Simulations for a number of case studies have been carried out, with or without mosaic surface representation and with or without atmospheric disaggregation, and evaluated with respect to the surface state variables and the turbulent surface exchange fluxes of sensible and latent heat. The results are compared with the high-resolution fully coupled COSMO simulations. The results clearly demonstrate the high importance of accounting for subgrid-scale surface heterogeneity. It is shown that the atmospheric disaggregation leads to clear additional improvements in the structures of the two-dimensional surface state variable fields, but to only marginally impacts on the simulation of the turbulent surface exchange fluxes. A detailed analysis of these results identifies strongly correlated errors in atmospheric and surface variables in the mosaic approach as the main reason for the latter. The effects of these errors largely cancel out in the flux parameterization, and thus explain the comparably good results for the fluxes in the mosaic approach without atmospheric disaggregation despite inferior performance for the surface state variables themselves. Inserting noise in the disaggregation scheme leads to a deterioration of the results.

Schomburg, A.; Venema, V.; Ament, F.; Simmer, C.

2012-05-01

391

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

Microsoft Academic Search

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

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

2006-01-01

392

Identification of rock weathering and environmental control in arid catchments (northern Xinjiang) of Central Asia  

NASA Astrophysics Data System (ADS)

Chemical weathering is an integral part of the earth surface processes, whose spatial patterns and controlling factors on continental scale are still not fully understood. Highlands of the Asian continent have been shown having some of the highest observed rates of chemical weathering yet reported. However, the paucity of river gauge data in many of these terrains has limited determination of chemical weathering budget in a continental scale. A dataset of three large watersheds throughout northern Xinjiang in Central Asia is used to empirically identify chemical weathering regimes and interpret the underlying controlling factors. Detailed analysis of major ion ratios and a forward model of mass budget procedure are presented to distinguish the relative significances and contributions of silicate, carbonate weathering and evaporite dissolution. The analytical results show that carbonic acid is the most important weathering agent to the studied watersheds. Silicate weathering contributes, on average, ˜17.8% (molar basis) of total cations on a basin wide scale with an order of Zhungarer > Erlqis > Yili, indicating that silicate weathering, however, does not seem to be intense in the study basins. Evaporite dissolution, carbonate weathering and precipitation input contribute 43.6%, 29.7% and 8.9% of the total dissolved cations on average for the whole catchment, respectively. The three main morphological and hydrological units are reflected in water chemistry. Rivers from the montane areas (recharge area) of the three watersheds are very dilute, dominated by carbonate and silicate weathering, whereas the rivers of piedmont areas as well as the rivers of the sedimentary platform (runoff area) are dominated by carbonate weathering, and rivers of desert plain in the central Zhungarer basin (discharge area) are dominated by evaporite dissolution and are SO4 rich. This spatial pattern indicates that, beside lithology, runoff conditions have significant role on the regional chemical weathering regimes. Chemical weathering processes in the areas appear to be significantly climate controlled, displaying a tight correlation with runoff and aridity. Carbonate weathering are mostly influenced by runoff, which is higher in the mountainous part of the studied basins. The identification of chemical weathering regimes from our study confirmed the weathering potential and complexity of temperate watersheds in arid environment and that additional studies of these terrains are warranted. However, because the dominant weathering reactions in the sedimentary platform of northern Xinjiang are of carbonates and evaporites rather than silicate minerals, and the climatic factors have important role on the rock weathering regimes, we think that weathering at the arid temperate drainage system (Central Asia) is maybe not an important long-term sink for atmospheric CO2, if the future climate has no great change.

Zhu, Bingqi; Yu, Jingjie; Qin, Xiaoguang; Rioual, Patrick; Zhang, Yichi; Liu, Ziting; Mu, Yan; Li, Hongwei; Ren, Xiaozong; Xiong, Heigang

2013-04-01

393

Sensitivity of large-scale atmospheric analyses to humidity observations and its impact on the global water cycle and tropical and extratropical weather systems in ERA40  

Microsoft Academic Search

Reanalysis data obtained from data assimilation are increasingly used for diagnostic studies of the general circulation of the atmosphere, for the validation of modelling experiments and for estimating energy and water fluxes between the Earth surface and the atmosphere. Because fluxes are not specifically observed, but determined by the data assimilation system, they are not only influenced by the utilized

L. Bengtsson; K. I. Hodges; S. Hagemann

2004-01-01

394

HI Observations of Giant Low Surface Brightness Galaxies  

Microsoft Academic Search

We have used the Nancay Radio Telescope to obtain new global HI data for 16\\u000agiant low surface brightness (LSB) galaxies. Our targets have optical\\u000aluminosities and disk scale lengths at the high end for spiral galaxies\\u000a(L_B~10^10 Lsun and h_r>~6 kpc for H_0=75 km\\/s\\/Mpc), but they have diffuse\\u000astellar disks, with mean disk surface brightnesses ~1 magnitude or more

L. D. Matthews; W. van Driel; D. Monnier-Ragaigne

2000-01-01

395

Observation of sulfur on the surface of giant aurothiol nanoclusters.  

PubMed

We report the study of aurothiol nanoclusters using high-resolution electron microscopy, energy loss spectroscopy, X-ray photoelectron spectroscopy, Auger spectroscopy, and microscopy. It is concluded that the sulfur atoms are located on the surface of the gold nanoparticles in both (100) and (111) microfacets. The X-ray photoelectron spectroscopy data show that there is a Au-Au bond as well as a Au-S bond. Auger depth profile measurements made by sputtering of the nanoparticles corroborates that the sulfur is located on the surface of the nanoparticle. Quantitative Auger analysis indicates a ratio Au/S between approximately 1.79 and 1.98. PMID:12908328

Gutierrez-Wing, C; Ascencio, J A; De la Cruz, W; Cota, L; Jose-Yacaman, M

2002-02-01

396

Destructive Weather  

NSDL National Science Digital Library

What are the effects of different types of destructive weather? Learn All About Hurricanes Record on your chart 3 things that you learned. Watch a Hurricane Video These are the devastating Effects of Hurricanes Learn All About Tornadoes Record on your chart 3 things that you learned. Watch a Tornado Video These are the devastating Effects of tornadoes Learn All About Thunderstorms Record on your chart 3 things that you learned. These are the devastating Effects of thunderstorms Follow these important tips To keep safe. ...

Alizabethirwin

2010-11-03

397

Weather Tamers  

NSDL National Science Digital Library

Problem-based learning experiences that extend at least two weeks provide an opportunity for students to investigate a real-world problem while learning science content and skills in an exciting way. Meteorology provides a wealth of problems students can investigate while learning specific science concepts and skills found frequently in middle level national and state curricula standards. The hands-on activity described in this article helps students learn about the science behind weather events by planning, constructing, and testing models of cities exposed to a series of simulated hurricanes and tornado conditions.

Sterling, Donna R.; Frazier, Wendy M.

2007-03-01

398

Observations of Fluxes and Inland Breezes over a Heterogeneous Surface  

Microsoft Academic Search

Repeated aircraft runs at about 33 m over heterogeneous terrain are analyzed to study the spatial variability of the mesoscale flow and turbulent fluxes. An irrigated area, about 12 km across, generates a relatively cool moist inland breeze. As this air flows out over the warmer, drier surrounding land surface, an internal boundary layer develops within the inland breeze, which

L. Mahrt; Jielun Sun; Dean Vickers; J. I. MacPherson; J. R. Pederson; R. L. Desjardins

1994-01-01

399

Observation of Sea Ice Surface Thermal States Under Cloud Cover.  

National Technical Information Service (NTIS)

Clouds interfere with the distribution of short-wave and long-wave radiations over sea ice, and thereby strongly affect the surface energy balance in polar regions. To evaluate the overall effects of clouds on climatic feedback processes in the atmosphere...

S. V. Nghiem D. K. Perovich A. J. Gow R. Kwok D. G. Barber J. C. Comiso

2001-01-01

400

Surface degradation of HTV silicone rubber and EPDM used for outdoor insulators under accelerated ultraviolet weathering condition  

Microsoft Academic Search

The chemistry of surface degradation by ultraviolet light (UV) of high temperature vulcanized dimethyl silicone rubber (HTV SIR) and ethylene propylene diene ter-polymer (EPDM), has been studied by many researchers. Insulators fabricated from these materials are normally \\

Bok-Hee Youn; Chang-Su Huh

2005-01-01

401

Comparison of Arctic clouds between European Center for Medium-Range Weather Forecasts simulations and Atmospheric Radiation Measurement Climate Research Facility long-term observations at the North Slope of Alaska Barrow site  

NASA Astrophysics Data System (ADS)

This study evaluated the European Center for Medium-Range Weather Forecasts (ECMWF) model-simulated clouds and boundary layer (BL) properties based upon Atmospheric Radiation Measurement Climate Research Facility observations at the North Slope of Alaska site during 1999-2007. The ECMWF model-simulated near-surface humidity had seasonal dependent biases as large as 20%, while also experiencing difficulty representing BL temperature inversion height and strength during the transition seasons. Although the ECMWF model captured the seasonal variation of surface heat fluxes, it had sensible heat flux biases over 20 W m-2 in most of the cold months. Furthermore, even though the model captured the general seasonal variations of low-level cloud fraction (LCF) and liquid water path (LWP), it still overestimated the LCF by 20% or more and underestimated the LWP over 50% in the cold season. On average, the ECMWF model underestimated LWP by ˜30 g m-2 but more accurately predicted ice water path for BL clouds. For BL mixed-phase clouds, the model predicted water-ice mass partition was significantly lower than the observations, largely due to the temperature dependence of water-ice mass partition used in the model. The ECMWF model captured the general response of cloud fraction and LWP on large-scale vertical motion changes but overpredicted the magnitude of the difference, especially for LWP. The new cloud and BL schemes of the ECMWF model that were implemented after 2003 only resulted in minor improvements in BL cloud simulations in summer. These results indicate that significant improvements in cold season BL and mixed-phase cloud processes in the model are needed.

Zhao, Ming; Wang, Zhien

2010-12-01

402

Quantitative retrieval of soil moisture content and surface roughness from multipolarized radar observations of bare soil surfaces  

Microsoft Academic Search

A semiempirical polarimetric backscattering model for bare soil surfaces is inverted directly to retrieve both the volumetric soil moisture content Mv and the rms surface height s from multipolarized radar observations. The rms surface height s and the moisture content Mv can be read from inversion diagrams using the measurements of the cross-polarized backscattering coefficient ?vh0 and the copolarized ratio

Yisok Oh

2004-01-01

403

Summer Weather on Haleakala, Maui.  

National Technical Information Service (NTIS)

Meteorological observations from the summit of Haleakala, Maui, high-resolution satellite imagery, and rainfall climatology are examined to determine diurnal and day-to-day variations in weather both at the summit and along the slopes. Results show larges...

S. W. Lyons

1979-01-01

404

Erosion rates and weathering history of rock surfaces associated with Aboriginal rock art engravings (petroglyphs) on Burrup Peninsula, Western Australia, from cosmogenic nuclide measurements  

NASA Astrophysics Data System (ADS)

The Burrup Peninsula and surrounding Dampier Archipelago, in Western Australia, contain the world's largest known gallery of rock art engravings (petroglyphs), estimated to number up to 1 million images. The peninsula is also the site of major industrial development and there are concerns that industrial emissions may adversely affect the stability and longevity of the rock art. We have studied the natural processes and rates of weathering and erosion, including the effects of fire, that affect the stability of rock surfaces and hence the longevity of the rock art, using cosmogenic nuclides. The concentration of 10Be in quartz yields erosion rates in the range 0.15–0.48 mm/1000 years on horizontal rock surfaces and 0.34–2.30 mm/1000 years on vertical rock faces. The former, largely caused by mm-scale surface flaking, are amongst the lowest erosion rates measured by cosmogenic nuclides anywhere in the world. The latter are inferred to represent a combination of mm-scale flaking and very rare centimetre- to metre-scale block falls, controlled by failure along joint planes. Such low erosion rates result from a combination of resistant rocks, low relief and low rainfall, favouring long-term preservation of the petroglyphs – long enough to encompass the known period of human settlement in Australia.

Pillans, Brad; Fifield, L. Keith

2013-06-01

405

A Residual Kriging method for the reconstruction of 3D high-resolution meteorological fields from airborne and surface observations  

NASA Astrophysics Data System (ADS)

Manned light aircrafts and remotely piloted aircrafts represent very valuable and flexible measurement platforms for atmospheric research, as they are able to provide high temporal and spatial resolution observations of the atmosphere above the ground surface. In the present study the application of a geostatistical interpolation technique called Residual Kriging (RK) is proposed for the mapping of airborne measurements of scalar quantities over regularly spaced 3D grids. In RK the dominant (vertical) trend component underlying the original data is first extracted to filter out local anomalies, then the residual field is separately interpolated and finally added back to the trend; the determination of the interpolation weights relies on the estimate of the characteristic covariance function of the residuals, through the computation and modelling of their semivariogram function. RK implementation also allows for the inference of the characteristic spatial scales of variability of the target field and its isotropization, and for an estimate of the interpolation error. The adopted test-bed database consists in a series of flights of an instrumented motorglider exploring the atmosphere of two valleys near the city of Trento (in the southeastern Italian Alps), performed on fair-weather summer days. RK method is used to reconstruct fully 3D high-resolution fields of potential temperature and mixing ratio for specific vertical slices of the valley atmosphere, integrating also ground-based measurements from the nearest surface weather stations. From RK-interpolated meteorological fields, fine-scale features of the atmospheric boundary layer developing over the complex valley topography in connection with the occurrence of thermally-driven slope and valley winds, are detected. The performance of RK mapping is also tested against two other commonly adopted interpolation methods, i.e. the Inverse Distance Weighting and the Delaunay triangulation methods, comparing the results of a cross-validation procedure.

Laiti, Lavinia; Zardi, Dino; de Franceschi, Massimiliano; Rampanelli, Gabriele

2013-04-01

406

Global Fields of Soil Moisture and Land Surface Evapotranspiration Derived from Observed Precipitation and Surface Air Temperature  

Microsoft Academic Search

The global fields of normal monthly soil moisture and land surface evapotranspiration are derived with a simple water budget model that has precipitation and potential evapotranspiration as inputs. The precipitation is observed and the potential evapotranspiration is derived from the observed surface air temperature with the empirical regression equation of Thornthwaite. It is shown that at locations where the net

Y. Mintz; G. K. Walker

1993-01-01

407

Snow accumulation, surface height change, and firn densification at Summit, Greenland: Insights from 2 years of in situ observation  

NASA Astrophysics Data System (ADS)

Weekly measurements of surface height change were made at an accumulation forest of 100 stakes at Summit, Greenland, over a 2-year period (17 August 2000 to 8 August 2002). On average, the surface height relative to the stakes increased 64 (±4.8) cm in the first year and 65 (±5.3) cm in the second, identical to the average (65 ± 4.5 cm yr-1) previously reported for the period 1991-1995 in a similar forest 28 km to the southwest. The continuous 2-year data set indicates that the rate of surface rise was not constant, with the summers of 2001 and 2002 both showing markedly slower increases. On-site weather observations suggest that more new snow fell during the summer months than in any other season, consistent with results from previous snow pit and modeling studies yet apparently at odds with the slow rate of height increase. Density profiles from a series of 1-m-deep snow pits sampled monthly reveal that the thickness of the most recent year of accumulated snow (25 cm water equivalent) decreased rapidly between late May and early July, and the layers remained thin through early September. The thinning of the top year is clearly due to compaction in the snowpack. Combining the observed variations in annual layer thickness with a linear height increase based on assumed constant accumulation at 0.18 cm d-1 explains much of the variation in surface height found in the stake measurements. Estimated