Papers by Siri Pritam Khalsa
ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C, 2011
A new method is described to determine irradiance distributions on receivers and targets from hel... more A new method is described to determine irradiance distributions on receivers and targets from heliostats or other collectors for concentrating solar power applications. The method uses a CCD camera, and, unlike previous beam characterization systems, it does not require additional sensors, calorimeters, or flux gauges on the receiver or target. In addition, spillage can exist (the beam does not need to be contained within the target). The only additional information required besides the digital images recorded from the CCD camera is the direct normal irradiance and the reflectivity of the receiver. Methods are described to calculate either an average reflectivity or a reflectivity distribution for the receiver using the CCD camera. The novel feature of this new PHLUX method is the use of recorded images of the sun to scale both the magnitude of each pixel value and the subtended angle of each pixel. A test was performed to evaluate the PHLUX method using a heliostat beam on the central receiver tower at the National Solar Thermal Test Facility in Albuquerque, NM. Results showed that the PHLUX method was capable of producing an accurate flux map of the heliostat beam with a relative error in the peak flux of 2%.
Mobile computing device configured to compute irradiance, glint, and glare of the sun
Inferring the Response of a Glacier System to Climate Change based on Observations of Individual Benchmark Glaciers
2006 IEEE International Symposium on Geoscience and Remote Sensing, 2006
ABSTRACT First Page of the Article
Convectivc Elements in the Marine Atmospheric Boundary Layer. Part II: Entrainment at the Capping Inversion
Journal of Climate and Applied Meteorology, 1987
ABSTRACT
Intercalibration of near-real-time snow and sea ice products from passive microwave Data
2010 11th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment, 2010
Global estimates of snow and sea ice from passive microwave imagery are among the longest satelli... more Global estimates of snow and sea ice from passive microwave imagery are among the longest satellite-derived climate records in existence. The speed of observed changes in the cryosphere is pushing demand for near-real-time information that can provide at least preliminary estimates of evolving conditions. Such data are also valuable in the production of other geophysical products and as input to
IEEE Geoscience and Remote Sensing Magazine, 2013
<title>NASA's EOSDIS: options for data providers</title>
Advanced and Next-Generation Satellites, 1995
EOSDIS, the data and information system being developed by NASA to support interdisciplinary eart... more EOSDIS, the data and information system being developed by NASA to support interdisciplinary earth science research into the 21st century, will do more than manage and distribute data from EOS-era satellites. It will also promote the exchange of data, tools, and research results across disciplinary, agency, and national boundaries. This paper describes the options that data providers will have for interacting with the EOSDIS Core System (ECS), the infrastructure of EOSDIS. The options include: using the ECS advertising service to announce the availability of data at the provider's site; submitting a candidate data set to one of the Distributed Active Archive Centers (DAACs); establishing a data server that will make the data accessible via ECS and establishing Local Information Manager (LIM) which would make the data available for multi-site searches. One additional option is through custom gateway interfaces which would provide access to existing data archives. The gateway, data server, and LIM options require the implementation of ECS code at the provider site to insure proper protocols. The advertisement and ingest options require no part of ECS design to reside at the provider site.
Near-Real-Time Global Ice Concentration from Spaceborne Passive Microwave Sensors
OCEANS 2006, 2006
Near real-time Ice and Snow Extent (NISE) estimates, produced and distributed by the National Sno... more Near real-time Ice and Snow Extent (NISE) estimates, produced and distributed by the National Snow and Ice Data Center, are presented. The estimates, derived from the DMSP SSM/I passive microwave instrument, provides daily, global, near real-time (&lt; 24 hrs) fields of sea ice concentrations and snow extent. We summarize both the science algorithms and systems engineering involved in producing a
Polar Record, 1995
The Earth's high-latitude regions are of critical importance in many climate-change scenarios... more The Earth's high-latitude regions are of critical importance in many climate-change scenarios, but a time continuous, spatially complete, and well-calibrated record of tropospheric temperatures is needed in order to assess past and future climate changes. Studies of recently compiled upper-air data sets show no evidence of CO2-induced warming, but the spatial pattern of tropospheric temperature variability in the Arctic has not been thoroughly examined. This study analyzes a 108-month segment of the data record from the TIROS Operational Vertical Sounder (TOVS) aboard NOAA polar-orbiting satellites to examine both the spatial and temporal variability of atmospheric temperature in the Arctic.Temperature retrievals based on clear-column radiances archived at NOAA/NESDIS were done using algorithms tuned to Arctic conditions. The retrieved temperatures compared well with Arctic rawinsonde data, and include lowlevel inversions that are often problematic for satellite retrievals. The ...
Journal of the Atmospheric Sciences, 1985
Direct Sampling of Entrainment Events in a Marine Stratocumulus Layer
Journal of the Atmospheric Sciences, 1993
Entrainment mixing and the stability of a marine stratocumulus layer are investigated using aircr... more Entrainment mixing and the stability of a marine stratocumulus layer are investigated using aircraft data gathered during the FIRE marine stratocumulus experiment. Direct measurement of entrainment events is accomplished through conditional sampling based on ozone mixing ratio. This enables the identification of evaporatively cooled, negatively buoyant events that could otherwise only be inferred by thermodynamic jump conditions at cloud top.
Journal of Geophysical Research, 1989
Fast response data taken aboard the National Oceanic and Atmospheric Administration WP-3D aircraf... more Fast response data taken aboard the National Oceanic and Atmospheric Administration WP-3D aircraft are used to determine the structure of atmospheric boundary layer turbulence on either side of a well-developed sea surface temperature front southwest of Bermuda. The data were taken on February 17, 1986, as part of the Frontal Air-Sea Interaction Experiment (FASINEX). A broad region of low-humidity air extending from 15 km to 35 km south of the front is probably due to the presence of a frontally induced secondary circulation. Evidence for a secondary flow is found in both the time series of atmospheric variables and the statistics obtained from conditionally sampled updrafts and downdrafts in the transect across the SST front. Larger sea-air temperature and humidity differences on the warm (south) side of the front give rise to surface layer sensible and latent heat and buoyancy fluxes that are larger than those on the cold side. Turbulence structure appears to be influenced as much by the presence of strong wind shear at the top of the boundary layer as by differing conditions at the surface on either side of the front. A larger rate of entrainment on the warm side of the front is indicated by the greater influence of low-momentum air from the overlying shear layer on updrafts in the upper part of the mixed layer, as well as the more frequent overturning of-cool/moist updrafts and warm/dry downdrafts. It is conjectured that the larger entrainment rate i,5, due to the interaction between the inversion layer and more energetic updrafts produced by greater surface forcing on the warm side of the front. 1. tal variations in the turbulent fluxes in the MABL occur on spatial scales that are comparable with the scales of horizontal variation of SST associated with an oceanic eddy and that different horizontal scales of turbulence occur on either side of the SST gradient [Guymet et al., 1983]. Greenhut [1982] found large differences between turbulent fluxes and bulk Copyright 1989 by the American Geophysical Union. Paper number 89JC00080. 0148-0227/89/89J C-00080505.00 transfer coefficients on either side of the strong SST discontinuity associated with the North Equatorial Countercurrent in the eastern Pacific Ocean. The SST front investigated during FASINEX occurs in a region where Ekman transport induced by mid-latitude westerlies and tradewind easterlies enhances the large-scale north-south temperature gradient in the ocean. The front is relatively persistent and most pronounced from late fall to early spring. During FASINEX, typical changes in SST across the front were equal to or greater than 2øC over distances of less than a few kilometers. The processes responsible for these very sharp discontinuities in SST are not fully understood at present (G. R. Halliwell and P. Cornilion, Large-scale SST variability in the western North Atlantic subtropical convergence zone during FASINEX, 2, Upper ocean heat balance and frontogenesis, submitted to Journal of Physical Oceanography, 1988). The FASINEX intensive study area, about 200 km square and centered at approximately 28øN, 70øW, was located far from continental influences. During most of the FASINEX intensive field program, including the day under study in this paper, synoptic-scale atmospheric forcing was small. The data used in this study were obtained aboard the NOAA WP-3D on February 17, 1986 (Julian day 48), when several aircraft flew a coordinated mission over an east-west segment of the SST front at 28.2øN. The locations of the SST front and the WP-3D flight path are shown in Figure 1. The frontal location was obtained by Halliwell et al. [1987], using satellite infrared imagery. Additional observations of the front taken aboard the National Center for Atmospheric Research (NCAR) Electra and the research vessels Oceanus and Endeavor are in good agreement with the frontal pattern
Journal of Geophysical Research, 1991
Shipboard, aircraft, and satellite atmospheric data are examined to determine the representativen... more Shipboard, aircraft, and satellite atmospheric data are examined to determine the representativeness ofthe Frontal Air-Sea Interaction Experiment (FASINEX) intensive measurement period, Phase II, in terms of climatology, atmospheric forcing, the general structure of the marine atmospheric boundary layer (MABL), and variability in boundary layer properties affecting air-ocean dynamics and thermodynamics. With regard to climatology, conditions observed during the intensive period were typical in terms of air-sea temperature differences, surface pressure patterns, cloud cover, and storm tracks. Storm system variabilities, such as the air temperature behind cold fronts, wind stress maxima occurring after frontal passage, the times for clockwise vector wind shifts associated with the frontal systems, and the systems' speeds, are estimated and emphasized in synoptic-scale characterizations, since these can be related to observed ocean responses. The local ocean surface variability was observed to have an influence on regional boundary layer properties and on air-sea interaction parameters even in the presence of the atmospheric storms.
IEEE Transactions on Geoscience and Remote Sensing, 2009
OWorf, 070ro 1N I&. REPORT SECURITY CLASSIFICATION 1b, RESTRICTIVE MARKINGS UNCLASSIFIED 2u 3. DI... more OWorf, 070ro 1N I&. REPORT SECURITY CLASSIFICATION 1b, RESTRICTIVE MARKINGS UNCLASSIFIED 2u 3. DISTRIIUTIONIAVAILABILITY OF REPORT NAD Aa228p43b3 UNLIMITED 4. PERFORMING ORGANIZATION REPORT NUMBER(S) S. MONITORING ORGANIZATION REPORT NUMBE 1531940 68. NAEOF PERFORMING ORGANIZATION [6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATIO University of COlorado (6C. ADDRESS (City, Statt, and ZIP Code) 7b. ADDRESS(City, State, and ZIPC CIRES Boulder, CO 80309-0449 &a. NAME OF FUNDING/SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION-(if applicable) ONR .... N00014-84-K-0405 Sr. ADDRESS (City, State, and ZIP Code)-10. SOURCE OF FUNDING NUMBERS
This report summarizes the experimental and modeling effort undertaken to understand solute mixin... more This report summarizes the experimental and modeling effort undertaken to understand solute mixing in a water distribution network conducted during the last year of a 3-year project. The experimental effort involves measurement of extent of mixing within different configurations of pipe networks, measurement of dynamic mixing in a single mixing tank, and measurement of dynamic solute mixing in a combined network-tank configuration. High resolution analysis of turbulence mixing is carried out via high speed photography as well as 3D finite-volume based Large Eddy Simulation turbulence models. Macroscopic mixing rules based on flow momentum balance are also explored, and in some cases, implemented in EPANET. A new version EPANET code was developed to yield better mixing predictions. The impact of a storage tank on pipe mixing in a combined pipe-tank network during diurnal fill-and-drain cycles is assessed. Preliminary comparison between dynamic pilot data and EPANET-BAM is also reported.
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Papers by Siri Pritam Khalsa