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Sample records for cloud climatology project

  1. Properties of deep convective clouds in the ISCCP Pilot Data Set. [International Satellite Cloud Climatology Project

    NASA Technical Reports Server (NTRS)

    Del Genio, Anthony D.; Yao, Mao-Sung

    1987-01-01

    Statistics on tropical deep convective clouds in the International Satellite Cloud Climatology Project Pilot Data Set are compiled by binning daytime data over areas of 2 X 2.5, 4 X 5, and 8 X 10 degrees. To isolate the convective clouds, only pixels with minimum visible optical thickness of 32 and maximum cloud top pressure of 550 mb are considered. Maps of convective cloud cover and frequency of convective events and frequency histograms of deep convective cloud pixels and cloud top pressures are presented.

  2. The International Satellite Cloud Climatology Project (ISCCP) - The first project of the World Climate Research Programme

    NASA Technical Reports Server (NTRS)

    Schiffer, R. A.; Rossow, W. B.

    1983-01-01

    The first project of the World Climate Research Program is the International Satellite Cloud Climatology Project, (ISCCP) whose objective is the collection and analysis of satellite radiance data in order to infer the global distribution of cloud radiative properties and improve the modeling of cloud effects on climate. The operational component of ISCCP takes advantage of the global coverage provided by the current and planned international array of geostationary and polar-orbiting meteorological satellites in the 1980s. It will produce a five-year global radiance and cloud data set. The research component of ISCCP will coordinate studies to validate climatology, improve cloud analysis algorithms, improve cloud effects modelling, and investigate the role of clouds in the atmospheric radiation budget and hydrologic cycle.

  3. Recent Trends of the Tropical Hydrological Cycle Inferred from Global Precipitation Climatology Project and International Satellite Cloud Climatology Project data

    NASA Technical Reports Server (NTRS)

    Zhou, Y. P.; Xu, Kuan-Man; Sud, Y. C.; Betts, A. K.

    2011-01-01

    Scores of modeling studies have shown that increasing greenhouse gases in the atmosphere impact the global hydrologic cycle; however, disagreements on regional scales are large, and thus the simulated trends of such impacts, even for regions as large as the tropics, remain uncertain. The present investigation attempts to examine such trends in the observations using satellite data products comprising Global Precipitation Climatology Project precipitation and International Satellite Cloud Climatology Project cloud and radiation. Specifically, evolving trends of the tropical hydrological cycle over the last 20-30 years were identified and analyzed. The results show (1) intensification of tropical precipitation in the rising regions of the Walker and Hadley circulations and weakening over the sinking regions of the associated overturning circulation; (2) poleward shift of the subtropical dry zones (up to 2deg/decade in June-July-August (JJA) in the Northern Hemisphere and 0.3-0.7deg/decade in June-July-August and September-October-November in the Southern Hemisphere) consistent with an overall broadening of the Hadley circulation; and (3) significant poleward migration (0.9-1.7deg/decade) of cloud boundaries of Hadley cell and plausible narrowing of the high cloudiness in the Intertropical Convergence Zone region in some seasons. These results support findings of some of the previous studies that showed strengthening of the tropical hydrological cycle and expansion of the Hadley cell that are potentially related to the recent global warming trends.

  4. Recent Trends of the Tropical Hydrological Cycle Inferred from Global Precipitation Climatology Project and International Satellite Cloud Climatology Project data

    NASA Technical Reports Server (NTRS)

    Zhou, Y. P.; Xu, Kuan-Man; Sud, Y. C.; Betts, A. K.

    2011-01-01

    Scores of modeling studies have shown that increasing greenhouse gases in the atmosphere impact the global hydrologic cycle; however, disagreements on regional scales are large, and thus the simulated trends of such impacts, even for regions as large as the tropics, remain uncertain. The present investigation attempts to examine such trends in the observations using satellite data products comprising Global Precipitation Climatology Project precipitation and International Satellite Cloud Climatology Project cloud and radiation. Specifically, evolving trends of the tropical hydrological cycle over the last 20-30 years were identified and analyzed. The results show (1) intensification of tropical precipitation in the rising regions of the Walker and Hadley circulations and weakening over the sinking regions of the associated overturning circulation; (2) poleward shift of the subtropical dry zones (up to 2deg/decade in June-July-August (JJA) in the Northern Hemisphere and 0.3-0.7deg/decade in June-July-August and September-October-November in the Southern Hemisphere) consistent with an overall broadening of the Hadley circulation; and (3) significant poleward migration (0.9-1.7deg/decade) of cloud boundaries of Hadley cell and plausible narrowing of the high cloudiness in the Intertropical Convergence Zone region in some seasons. These results support findings of some of the previous studies that showed strengthening of the tropical hydrological cycle and expansion of the Hadley cell that are potentially related to the recent global warming trends.

  5. Normalization and calibration of geostationary satellite radiances for the International Satellite Cloud Climatology Project

    NASA Technical Reports Server (NTRS)

    Desormeaux, Yves; Rossow, William B.; Brest, Christopher L.; Campbell, G. G.

    1993-01-01

    Procedures are described for normalizing the radiometric calibration of image radiances obtained from geostationary weather satellites that contributed data to the International Satellite Cloud Climatology Project. The key step is comparison of coincident and collocated measurements made by each satellite and the concurrent AVHRR on the 'afternoon' NOAA polar-orbiting weather satellite at the same viewing geometry. The results of this comparison allow transfer of the AVHRR absolute calibration, which has been established over the whole series, to the radiometers on the geostationary satellites. Results are given for Meteosat-2, 3, and 4, for GOES-5, 6, and 7, for GMS-2, 3, and 4 and for Insat-1B. The relative stability of the calibrations of these radiance data is estimated to be within +/- 3 percent; the uncertainty of the absolute calibrations is estimated to be less than 10 percent. The remaining uncertainties are at least two times smaller than for the original radiance data.

  6. The Nimbus-7 Global Cloud Climatology

    NASA Technical Reports Server (NTRS)

    Hwang, Paul H.; Kyle, H. Lee; Stowe, Larry L.; Pellegrino, P. P.; Yeh, H. Y. Michael

    1988-01-01

    The Nimbus-7 Global Cloud Climatology (N7GCC) has been produced from measurements made between April 1979 and March 1985 using the Temperature Humidity IR Radiometer and the Total Ozone Mapping Spectrometer on the Nimbus-7 satellite. The N7GCC gives, near local noon and midnight, the fractional area covered by high-level, middle-level, and low-altitude clouds, and the total fractional area covered by all clouds. Statistics for cirrus, deep convective, and warm low-altitude clouds and the cloud and clear-sky radiances with correlative surface temperatures are also included. The N7GCC is compared with other cloud data sets, including the International Satellite Cloud Climatology Project.

  7. The Nimbus-7 Global Cloud Climatology

    NASA Technical Reports Server (NTRS)

    Hwang, Paul H.; Kyle, H. Lee; Stowe, Larry L.; Pellegrino, P. P.; Yeh, H. Y. Michael

    1988-01-01

    The Nimbus-7 Global Cloud Climatology (N7GCC) has been produced from measurements made between April 1979 and March 1985 using the Temperature Humidity IR Radiometer and the Total Ozone Mapping Spectrometer on the Nimbus-7 satellite. The N7GCC gives, near local noon and midnight, the fractional area covered by high-level, middle-level, and low-altitude clouds, and the total fractional area covered by all clouds. Statistics for cirrus, deep convective, and warm low-altitude clouds and the cloud and clear-sky radiances with correlative surface temperatures are also included. The N7GCC is compared with other cloud data sets, including the International Satellite Cloud Climatology Project.

  8. Analysis of global cloudiness comparison of meteor, Nimbus 7, and international satellite cloud climatology project (ISCCP) satellite data

    SciTech Connect

    Mokhov, I.I.; Schlesinger, M.E.

    1993-07-20

    In this first paper of a three-part series on cloudienss we intercompare the simultaneous cloudiness data obtained from Meteor satellites, Nimbus 7, and the International Satellite Cloud Climatology Project (ISCCP) for the one-year period, July 1983 to June 1984. Four versions of ISCCP cloudiness are obtained from analyses of the ISCCP-C1 data. These versions differ in their requirements for temporal and spectral sampling. ISCCPs 1 and 2 require for each 2.5{degree} x 2.5{degree} latitude-longitude cell that there be observations at least (N{sub d} = ) 20 of the 28-31 possible days per month and at least (N{sub h} = ) 5 of the 8 possible 3 hourly times each such day; ISCCPs 3 and 4 require only N{sub d} = 1 and N{sub h} = 1. The ISCCP 1-4 intercomparison shows that (1) the cloudiness differences due to the above temporal sampling are smaller than those due to the above spectral sampling; (2) both spectral and temporal sampling effects are larger for the northern hemisphere than for the southern hemisphere; and (3) the difference between zonal mean cloudiness with and without visible information generally increases with latitude from polar night to about 60{degree} latitude in the summer hemisphere. A special observational program in both the Arctic and the Antarctic is proposed to resolve the discrepancies among the satellite and ground-based cloudiness observations in polar latitudes.

  9. Analysis and comparison of diurnal variations of cloud radiative forcing: Earth Radiation Budget Experiment and International Satellite Cloud Climatology Project results

    SciTech Connect

    Kim, Y.

    1994-10-01

    Cloud radiative forcing (CRF) is the radiative impact of clouds on the Earth`s radiation budget. This study examines the diurnal variations of CRF using the Earth Radiation Budget Experiment (ERBE) monthly hourly flux data and the flux data derived from the International Satellite Cloud Climatology Project (ISCCP) using the Goddard Institute for Space Studies general circulation model radiation code. The results for the months of April, July, and October 1985 and January 1986 are analyzed. We found that, in general, two data sets agreed. For longwave (LW) CRF the diurnal range over land is generally greater than that observed over oceans. For the 4-month averages the ERBE values are 15.8 W/sq m and 6.8 W/sq m for land and ocean, respectively, compared with the ISCCP calculated values of 18.4 W/sq m and 8.0 W/sq m, respectively. The land/ocean contrast is largely associated with changes in cloud amount and the temperature difference between surface and cloud top. It would be more important to note that the clear-sky flux (i.e., surface temperature) variabilities are shown to be a major contributor to the large variabilities over land. The maximum diurnal range is found to be in the summer hemisphere, and the minimum values in the winter hemisphere. It is also shown that the daytime maximum and the nighttime minimum are seen over large portions of land, whereas they occur at any local hour over most oceans. For shortwave (SW) CRF the daytime maximum values are about twice as large as monthly averages, and their highest frequency occurs at local noon, indicating that solar insolation is a primary factor for the diurnal variation of SW CRF. However, the comparison of the ERBE data with the ISCCP results demonstrated that the largest differences in the diurnal range and monthly mean of LW CRF were associated with tropical convergence zones, where clear-sky fluxes could be easily biased by persistent cloudiness and the inadequate treatment of the atmospheric water vapor.

  10. Analysis and comparison of diurnal variations of cloud radiative forcing: Earth Radiation Budget Experiment and International Satellite Cloud Climatology Project results

    NASA Technical Reports Server (NTRS)

    Kim, Yongseung

    1994-01-01

    Cloud radiative forcing (CRF) is the radiative impact of clouds on the Earth's radiation budget. This study examines the diurnal variations of CRF using the Earth Radiation Budget Experiment (ERBE) monthly hourly flux data and the flux data derived from the International Satellite Cloud Climatology Project (ISCCP) using the Goddard Institute for Space Studies general circulation model radiation code. The results for the months of April, July, and October 1985 and January 1986 are analyzed. We found that, in general, two data sets agreed. For longwave (LW) CRF the diurnal range over land is generally greater than that observed over oceans. For the 4-month averages the ERBE values are 15.8 W/sq m and 6.8 W/sq m for land and ocean, respectively, compared with the ISCCP calculated values of 18.4 W/sq m and 8.0 W/sq m, respectively. The land/ocean contrast is largely associated with changes in cloud amount and the temperature difference between surface and cloud top. It would be more important to note that the clear-sky flux (i.e., surface temperature) variabilities are shown to be a major contributor to the large variabilities over land. The maximum diurnal range is found to be in the summer hemisphere, and the minimum values in the winter hemisphere. It is also shown that the daytime maximum and the nighttime minimum are seen over large portions of land, whereas they occur at any local hour over most oceans. For shortwave (SW) CRF the daytime maximum values are about twice as large as monthly averages, and their highest frequency occurs at local noon, indicating that solar insolation is a primary factor for the diurnal variation of SW CRF. However, the comparison of the ERBE data with the ISCCP results demonstrated that the largest differences in the diurnal range and monthly mean of LW CRF were associated with tropical convergence zones, where clear-sky fluxes could be easily biased by persistent cloudiness and the inadequate treatment of the atmospheric water vapor.

  11. Analysis and comparison of diurnal variations of cloud radiative forcing: Earth Radiation Budget Experiment and International Satellite Cloud Climatology Project results

    NASA Technical Reports Server (NTRS)

    Kim, Yongseung

    1994-01-01

    Cloud radiative forcing (CRF) is the radiative impact of clouds on the Earth's radiation budget. This study examines the diurnal variations of CRF using the Earth Radiation Budget Experiment (ERBE) monthly hourly flux data and the flux data derived from the International Satellite Cloud Climatology Project (ISCCP) using the Goddard Institute for Space Studies general circulation model radiation code. The results for the months of April, July, and October 1985 and January 1986 are analyzed. We found that, in general, two data sets agreed. For longwave (LW) CRF the diurnal range over land is generally greater than that observed over oceans. For the 4-month averages the ERBE values are 15.8 W/sq m and 6.8 W/sq m for land and ocean, respectively, compared with the ISCCP calculated values of 18.4 W/sq m and 8.0 W/sq m, respectively. The land/ocean contrast is largely associated with changes in cloud amount and the temperature difference between surface and cloud top. It would be more important to note that the clear-sky flux (i.e., surface temperature) variabilities are shown to be a major contributor to the large variabilities over land. The maximum diurnal range is found to be in the summer hemisphere, and the minimum values in the winter hemisphere. It is also shown that the daytime maximum and the nighttime minimum are seen over large portions of land, whereas they occur at any local hour over most oceans. For shortwave (SW) CRF the daytime maximum values are about twice as large as monthly averages, and their highest frequency occurs at local noon, indicating that solar insolation is a primary factor for the diurnal variation of SW CRF. However, the comparison of the ERBE data with the ISCCP results demonstrated that the largest differences in the diurnal range and monthly mean of LW CRF were associated with tropical convergence zones, where clear-sky fluxes could be easily biased by persistent cloudiness and the inadequate treatment of the atmospheric water vapor.

  12. A Cloud Climatology of the Southern Great Plains ARM CART.

    NASA Astrophysics Data System (ADS)

    Lazarus, Steven M.; Krueger, Steven K.; Mace, Gerald G.

    2000-05-01

    Cloud amount statistics from three different sources were processed and compared. Surface observations from a National Centers for Environmental Prediction dataset were used. The data (Edited Cloud Report; ECR) consist of synoptic weather reports that have been edited to facilitate cloud analysis. Two stations near the Southern Great Plains (SGP) Cloud and Radiation Test Bed (CART) in north-central Oklahoma (Oklahoma City, Oklahoma and Wichita, Kansas) were selected. The ECR data span a 10-yr period from December 1981 to November 1991. The International Satellite Cloud Climatology Project (ISCCP) provided cloud amounts over the SGP CART for an 8-yr period (1983-91). Cloud amounts were also obtained from Micro Pulse Lidar (MPL) and Belfort Ceilometer (BLC) cloud-base height measurements made at the SGP CART over a 1-yr period. The annual and diurnal cycles of cloud amount as a function of cloud height and type were analyzed. The three datasets closely agree for total cloud amount. Good agreement was found in the ECR and MPL-BLC monthly low cloud amounts. With the exception of summer and midday in other seasons, the ISCCP low cloud amount estimates are generally 5%-10% less than the others. The ECR high cloud amount estimates are typically 10%-15% greater than those obtained from either the ISCCP or MPL-BLC datasets. The observed diurnal variations of altocumulus support the authors' model results of radiatively induced circulations.

  13. A cloud climatology of the Southern Great Plains ARM CART

    SciTech Connect

    Lazarus, S.M.; Krueger, S.K.; Mace, G.G.

    2000-05-15

    Cloud amount statistics from three different sources were processed and compared. Surface observations from a National Centers for Environmental Prediction dataset were used. The data (Edited Cloud Report; ECR) consist of synoptic weather reports that have been edited to facilitate cloud analysis. Two stations near the Southern Great Plains (SGP) Cloud and Radiation Test Bed (CART) in north-central Oklahoma (Oklahoma City, Oklahoma and Wichita, Kansas) were selected. The ECR data span a 10-yr period from December 1981 to November 1991. The International Satellite Cloud Climatology Project (ISCCP) provided cloud amounts over the SGP CART for an 8-yr period (1983--91). Cloud amounts were also obtained from Micro Pulse Lidar (MPL) and Belfort Ceilometer (BLC) cloud-base height measurements made at the SGP CART over a 1-yr period. The annual and diurnal cycles of cloud amount as a function of cloud height and type were analyzed. The three datasets closely agree for total cloud amount. Good agreement was found in the ECR and MPL-BLC monthly low cloud amounts. With the exception of summer and midday in other seasons, the ISCCP low cloud amount estimates are generally 5%--10% less than the others. The ECR high cloud amount estimates are typically 10%--15% greater than those obtained from either the ISCCP or MPL-BLC datasets. The observed diurnal variations of altocumulus support the authors' model results of radiatively induced circulations.

  14. Empirical and modeled synoptic cloud climatology of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Crane, R. G.

    1985-01-01

    A daily climatology of the atmospheric circulation of the Arctic and the associated cloud conditions were determined. These are used for comparisons with the variability of general circulation model, generated circulation, and cloud cover for the same region.

  15. Evaluation and Applications of Cloud Climatologies from CALIOP

    NASA Technical Reports Server (NTRS)

    Winker, David; Getzewitch, Brian; Vaughan, Mark

    2008-01-01

    Clouds have a major impact on the Earth radiation budget and differences in the representation of clouds in global climate models are responsible for much of the spread in predicted climate sensitivity. Existing cloud climatologies, against which these models can be tested, have many limitations. The CALIOP lidar, carried on the CALIPSO satellite, has now acquired over two years of nearly continuous cloud and aerosol observations. This dataset provides an improved basis for the characterization of 3-D global cloudiness. Global average cloud cover measured by CALIOP is about 75%, significantly higher than for existing cloud climatologies due to the sensitivity of CALIOP to optically thin cloud. Day/night biases in cloud detection appear to be small. This presentation will discuss detection sensitivity and other issues associated with producing a cloud climatology, characteristics of cloud cover statistics derived from CALIOP data, and applications of those statistics.

  16. Developing a cloud mask climatology covering two Meteosat satellite generations

    NASA Astrophysics Data System (ADS)

    Posselt, Rebekka; Stöckli, Reto; Liniger, Mark A.

    2013-04-01

    Long term cloud cover observations from satellites are fundamental for climate model validation and climate monitoring. Further, they support ground-based observations in regions with sparse coverage. Additionally, information on cloud cover is needed to derive other physical parameters such as surface radiation fluxes or clear sky and cloudy atmospheric states and is of high relevance for the solar energy sector. Within the current project phase of the Satellite Application Facility on Climate Monitoring (CM SAF) an algorithm to calculate a climatological cloud mask (or cloud cover probability) from Meteosat satellites is developed. The algorithm shall be applicable for both Meteosat first generation (1983-2005) and Meteosat second generation (2004-present) which significantly differ in their spectral properties. The algorithm linearly aggregates a set of continuous scores instead of the commonly used decision tree approach. The scores are calculated for different channels as well as different spatial and temporal settings. Each score yields a probability for the pixel's cloud cover. The final result, the cloud cover probability, is obtained by combining all available scores taking into account the varying performance of the scores during day and night and over snow. The uncertainty of the final cloud cover estimate is an inherent part of the probability. The algorithm is calibrated using cloud cover measurements from SYNOP stations located on the Meteosat disc. The subsequent validation is done at an independent set of collocated SYNOP/ARSA (Automated Radiosonde Archive) stations. The presentation introduces the applied cloud mask algorithm and presents the results of the validation for both satellite generations. The comparison of the two satellite generations addresses the climatological homogeneity of the future cloud mask climate data record which will be distributed by CM SAF after 2016. Special attention is also drawn to issues like the day-night-bias of

  17. Nimbus-7 global cloud climatology. II - First year results

    NASA Technical Reports Server (NTRS)

    Stowe, Larry L.; Yeh, H. Y. Michael; Wellemeyer, Charlie G.; Eck, Thomas F.; Kyle, H. Lee

    1989-01-01

    Results are presented on the analysis of the Nimbus-7 satellite data set obtained on regional and seasonal variations in global cloud cover. Four midseason months (April, July, and October 1979 and January 1980) were analyzed for the total cloud amount, the cloud amounts at high, middle, and low altitudes, the cirrus and deep convective clouds, and the cloud and clear-sky 11.5 micron-derived radiances; in addition, noon versus midnight cloud amounts were examined. The Nimbus-7 data are compared with three previously published cloud climatologies, and the differences among these data sets are discussed.

  18. Cloud cover over the equatorial eastern Pacific derived from July 1983 International Satellite Cloud Climatology Project data using a hybrid bispectral threshold method

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Harrison, Edwin F.; Gibson, Gary G.

    1987-01-01

    A set of visible and IR data obtained with GOES from July 17-31, 1983 is analyzed using a modified version of the hybrid bispectral threshold method developed by Minnis and Harrison (1984). This methodology can be divided into a set of procedures or optional techniques to determine the proper contaminate clear-sky temperature or IR threshold. The various optional techniques are described; the options are: standard, low-temperature limit, high-reflectance limit, low-reflectance limit, coldest pixel and thermal adjustment limit, IR-only low-cloud temperature limit, IR clear-sky limit, and IR overcast limit. Variations in the cloud parameters and the characteristics and diurnal cycles of trade cumulus and stratocumulus clouds over the eastern equatorial Pacific are examined. It is noted that the new method produces substantial changes in about one third of the cloud amount retrieval; and low cloud retrievals are affected most by the new constraints.

  19. A global climatology of clean and polluted clouds

    NASA Astrophysics Data System (ADS)

    Jiang, J. H.; Su, H.; Massie, S. T.; Schoeberl, M. R.; Livesey, N. J.

    2007-12-01

    Global cloud observations from CloudSat and Aura MLS are studied in combination with the new aerosol observations from CALIPSO and carbon monoxide (CO) measurements from Aura MLS to investigate global distribution and seasonal variation of clean and pollution contaminated clouds. Our study will focus on the cirrus cloud in the upper troposphere where MLS ice water content and CO measurements are available. Our approach is to use MLS CO to classify cirrus clouds as "clean" or "polluted", and to use CALIPSO aerosol to identify convective systems contaminated by aerosol particles. We define a "polluted" cloud by two criteria: one uses the coincident MLS CO measurements greater than a certain background value and the other uses the aerosol observations from CALIPSO. Surface emission source of CO and aerosol will be examined in parallel. This study compiles the climatologies of two sets of "polluted" clouds. These climatologies will be compared with that of the clean clouds to delineate how surface pollution alters the properties of upper tropospheric clouds. The results will be compared with model simulations as well. Preliminary analyses find high CO concentration co-exists with deep convective cores and cirrus anvils. Aerosols, however, are found collocated mostly with cirrus away from convective cores, where precipitation is not strongest. The spatial distribution and seasonal variation of "polluted" clouds will be presented at the meeting.

  20. Global cloud climatology from surface observations

    SciTech Connect

    Warren, S.

    1995-09-01

    Surface weather observations from stations on land and ships in the ocean are used to obtain the global distribution, at 5{sup o}x5{sup o} latitude-longitude resolution, of total cloud cover and the average amounts of the different cloud types: cumulus, cumulonimbus, stratus, stratocumulus, nimbostratus, altostratus, altocumulus, cirrus, cirrostratus, cirrocumulus, and fog. Diurnal and seasonal variations are derived, as well as interannual variations and multi-year trends. 3 refs., 3 figs.

  1. Albedo climatology analysis and the determination of fractional cloud cover

    NASA Technical Reports Server (NTRS)

    Curran, R. J.; Wexler, R.; Nack, M. L.

    1978-01-01

    Monthly and zonally averaged surface cover climatology data are presented which are used to construct monthly and zonally averaged surface albedos. The albedo transformations are then applied to the surface albedos, using solar zenith angles characteristic of the Nimbus 6 satellite local sampling times, to obtain albedos at the top of clear and totally cloud covered atmospheres. These albedos are then combined with measured albedo data to solve for the monthly and zonally averaged fractional cloud cover. The measured albedo data were obtained from the wide field of view channels of the Nimbus 6 Earth Radiation Budget experiment, and consequently the fractional cloud cover results are representative of the local sampling times. These fractional cloud cover results are compared with recent studies. The cloud cover results not only show peaks near the intertropical convergence zone, but the monthly migration of the position of these peaks follows general predictions of atmospheric circulation studies.

  2. The Global Precipitation Climatology Project: First Algorithm Intercomparison Project

    NASA Technical Reports Server (NTRS)

    Arkin, Phillip A.; Xie, Pingping

    1994-01-01

    The Global Precipitation Climatology Project (GPCP) was established by the World Climate Research Program to produce global analyses of the area- and time-averaged precipitation for use in climate research. To achieve the required spatial coverage, the GPCP uses simple rainfall estimates derived from IR and microwave satellite observations. In this paper, we describe the GPCP and its first Algorithm Intercomparison Project (AIP/1), which compared a variety of rainfall estimates derived from Geostationary Meteorological Satellite visible and IR observations and Special Sensor Microwave/Imager (SSM/I) microwave observations with rainfall derived from a combination of radar and raingage data over the Japanese islands and the adjacent ocean regions during the June and mid-July through mid-August periods of 1989. To investigate potential improvements in the use of satellite IR data for the estimation of large-scale rainfall for the GPCP, the relationship between rainfall and the fractional coverage of cold clouds in the AIP/1 dataset is examined. Linear regressions between fractional coverage and rainfall are analyzed for a number of latitude-longitude areas and for a range of averaging times. The results show distinct differences in the character of the relationship for different portions of the area. These results suggest that the simple IR-based estimation technique currently used in the GPCP can be used to estimate rainfall for global tropical and subtropical areas, provided that a method for adjusting the proportional coefficient for varying areas and seasons can be determined.

  3. Analysis of global cloudiness. 2: Comparison of ground-based and satellite-based cloud climatologies

    SciTech Connect

    Mokhov, I.I.; Schlesinger, M.E. |

    1994-08-01

    Cloud climatologies are developed and intercompared for International Satellite Cloud Climatology Project (ISCCO) (1983-1988), Meteor I (1971-1980), Meteor II (1979-1988), and Nimbus 7 (1979-1985) satellite observations, and for Berlyand and Strokina (1975, 1980) and Warren et al. (1986, 1988) ground-based observations. The satellite annual-mean, global- mean cloudiness, 0.57 +/- 0.05, is less than the ground-based value, 0.61 +/- 0.01, predominantly because of the low value for Nimbus 7. There is agreement between the satellite means of ISCCP, 0.62, and Meteor II, 0.61, and the ground-based means of Warren et al., 0.62, and Berlyand and Strokina, 0.60. Each satellite- and ground-based climatology shows that the hemispheric- mean cloudiness is larger in summer than that in winter in both the northern and southern hemispheres. Excluding Nimbus 7 observations, the zonal- mean cloudiness distributions for January, July, and July minus January display reasonably good agreement between 60 deg S and 60 deg N. In polar latitudes there is significant disagreement among the different climatologies, even in the sign of cloudiness changes from winter to summer. This evinces the need for special cloudiness experiments in polar regions, particularly in winter and summer.

  4. MERIS albedo climatology and its effect on the FRESCO+ O2 A-band cloud retrieval from SCIAMACHY data

    NASA Astrophysics Data System (ADS)

    Popp, Christoph; Wang, Ping; Brunner, Dominik; Stammes, Piet; Zhou, Yipin

    2010-05-01

    Accurate cloud information is an important prerequisite for the retrieval of atmospheric trace gases from spaceborne UV/VIS sensors. Errors in the estimated cloud fraction and cloud height (pressure) result in an erroneous air mass factor and thus can lead to inaccuracies in the vertical column densities of the retrieved trace gas. In ESA's TEMIS (Tropospheric Emission Monitoring Internet Service) project, the FRESCO+ (Fast Retrieval Scheme for Clouds from the Oxygen A-band) cloud retrieval is applied to, amongst others, SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY) data to determine these quantities. Effective cloud fraction and pressure are inverted by (i) radiative transfer simulations of top-of-atmosphere reflectance based on O2 absorption, single Rayleigh scattering, surface and cloud albedo in three spectral windows covering the O2 A-band and (ii) a subsequent fitting of the simulated to the measured spectrum. However, FRESCO+ relies on a relatively coarse resolution surface albedo climatology (1° x 1°) compiled from GOME (Global Ozone Monitoring Experiment) measurements in the 1990's which introduces several artifacts, e.g. an overestimation of cloud fraction at coastlines or over some mountainous regions. Therefore, we test the substitution of the GOME climatology with a new land surface albedo climatology compiled for every month from MEdium Resolution Imaging Spectrometer (MERIS) Albedomap data (0.05° x 0.05°) covering the period January 2003 to October 2006. The MERIS channels at 754nm and 775nm are located spectrally close to the corresponding GOME channels (758nm and 772nm) on both sides of the O2 A-band. Further, the increased spatial resolution of the MERIS product allows to better account for SCIAMACHY's pixel size of approximately 30x60km. The aim of this study is to describe and assess (i) the compilation and quality of the MERIS climatology (ii) the differences to the GOME climatology, and (iii) possible

  5. Climatology of cloud water content associated with different cloud types observed by A-Train satellites

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Jiang, Jonathan H.; Wang, Zhien; Su, Hui; Deng, Min; Massie, Steven

    2015-05-01

    This study investigates the climatology of vertical distributions of cloud liquid water content, ice water content, and cloud fraction (CFR) associated with eight different cloud types, by utilizing the combined CloudSat radar and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar measurements. The geographical and seasonal variations of these cloud properties for each cloud type are also analyzed. The cloud water content (CWC) of each cloud type is sorted by three parameters obtained from colocated satellite observations to investigate the relationships between large-scale conditions and the vertical structure of clouds. Results show that different cloud types have different altitudes of CWC and CFR peaks, and the altitude of CFR peak does not always overlap with that of CWC peak. Each type of cloud shows a clear asymmetric pattern of spatial distribution between Northern Hemisphere (NH) and Southern Hemisphere (SH). Stratocumulus and stratus clouds make the greatest contribution to the liquid water path, while the ice water path is mostly contributed by deep convective cloud over the tropics and nimbostratus over the middle and high latitudes. Over both middle and high latitudes, clouds have larger seasonal variation in the NH than in the SH. Over ocean, large CWCs of deep convective cloud, cirrus, and altostratus are above 7 km, and are associated with high convective available potential energy (>2000 J/kg), warm sea surface temperature (>303 K), and relatively high precipitation (>1 mm/h). Over land, most of the middle and high clouds have similar CWC distributions compared to those over ocean, but altocumulus and low clouds are quite different from those over ocean.

  6. A CERES-like Cloud Property Climatology Using AVHRR Data

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Bedka, K. M.; Yost, C. R.; Trepte, Q.; Bedka, S. T.; Sun-Mack, S.; Doelling, D.

    2015-12-01

    Clouds affect the climate system by modulating the radiation budget and distributing precipitation. Variations in cloud patterns and properties are expected to accompany changes in climate. The NASA Clouds and the Earth's Radiant Energy System (CERES) Project developed an end-to-end analysis system to measure broadband radiances from a radiometer and retrieve cloud properties from collocated high-resolution MODerate-resolution Imaging Spectroradiometer (MODIS) data to generate a long-term climate data record of clouds and clear-sky properties and top-of-atmosphere radiation budget. The first MODIS was not launched until 2000, so the current CERES record is only 15 years long at this point. The core of the algorithms used to retrieve the cloud properties from MODIS is based on the spectral complement of the Advanced Very High Resolution Radiometer (AVHRR), which has been aboard a string of satellites since 1978. The CERES cloud algorithms were adapted for application to AVHRR data and have been used to produce an ongoing CERES-like cloud property and surface temperature product that includes an initial narrowband-based radiation budget. This presentation will summarize this new product, which covers nearly 37 years, and its comparability with cloud parameters from CERES, CALIPSO, and other satellites. Examples of some applications of this dataset are given and the potential for generating a long-term radiation budget CDR is also discussed.

  7. CMIP5 models' shortwave cloud radiative response and climate sensitivity linked to the climatological Hadley cell extent

    NASA Astrophysics Data System (ADS)

    Lipat, Bernard R.; Tselioudis, George; Grise, Kevin M.; Polvani, Lorenzo M.

    2017-06-01

    This study analyzes Coupled Model Intercomparison Project phase 5 (CMIP5) model output to examine the covariability of interannual Southern Hemisphere Hadley cell (HC) edge latitude shifts and shortwave cloud radiative effect (SWCRE). In control climate runs, during years when the HC edge is anomalously poleward, most models substantially reduce the shortwave radiation reflected by clouds in the lower midlatitude region (LML; ˜28°S-˜48°S), although no such reduction is seen in observations. These biases in HC-SWCRE covariability are linked to biases in the climatological HC extent. Notably, models with excessively equatorward climatological HC extents have weaker climatological LML subsidence and exhibit larger increases in LML subsidence with poleward HC edge expansion. This behavior, based on control climate interannual variability, has important implications for the CO2-forced model response. In 4×CO2-forced runs, models with excessively equatorward climatological HC extents produce stronger SW cloud radiative warming in the LML region and tend to have larger climate sensitivity values than models with more realistic climatological HC extents.

  8. A 24-year climatology of cloud effects on the Earth's longwave radiation budget

    NASA Astrophysics Data System (ADS)

    Pyrina, Maria; Matsoukas, Christos; Fotiadi, Aggeliki; Papadimas, Christos; Hatzianastassiou, Nikos; Vardavas, Ilias

    2013-04-01

    A longwave (LW) radiative transfer model (RTM) was used together with monthly mean climatological data from global datasets to compute the global distribution of LW cloud radiative effect (CRE) at the top of atmosphere (TOA), within the atmosphere and at the Earth's surface, at 2.5˚x2.5˚ latitude-longitude resolution, for the 24-year period 1984-2007. The cloud data, namely cloud cover and optical depth, were derived from the latest D2 series of the International Satellite Cloud Climatology Project (ISCCP) Project, which includes 9 cloud types, distinguishing between low-, mid- and high-level and liquid and ice clouds. Supplementary data for surface and atmospheric parameters were taken from NCEP/NCAR, ECMWF, ISCCP-D2, and TOVS datasets. On a mean annual basis and global scale, clouds are found to warm the planet, by decreasing the outgoing LW radiation at TOA, by 17.8 W/m2, to cool the atmosphere, by decreasing the LW atmospheric absorption, by 11.9 W/m2 and to heat the surface by 29.7 W/m2. Nevertheless, there is a significant spatial variability of CREs. Thus, at pixel level and on year mean basis, clouds generally decrease the thermal emission of our planet by up to about 50 W/m2 but also induce planetary cooling, by up to about 2 W/m2 over central Antarctica's regions. The presence of low and middle clouds in the atmosphere induces an atmospheric cooling, by up to about 50 W/m2, while atmospheric warming is produced by high clouds along the inter-tropical convergence zone (by up to about 30 W/m2). The net LW radiation emitted by the surface is found to be reduced by clouds by up to 55 W/m2. The model CREs were validated at TOA through comparisons against high-quality ERBE-S4 CRE values over the 5-year period 1985-1989 and also against high-quality CERES-S4 CREs over the 7-year period 2001-2007. Model CREs were found to reasonably agree with both CERES and ERBE ones, with biases equal to -9.9 W/m2 and -7.1 W/m2, standard deviations of differences equal to 4

  9. A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing. Part III: Radiative Properties

    SciTech Connect

    Sassen, K.; Comstock, Jennifer M.

    2001-08-01

    In Part III of a series of papers describing the extended time high-cloud observations from the University of Utah Facility for Atmospheric Remote Sensing (FARS) supporting the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment, the visible and infrared radiative properties of cirrus clouds over Salt Lake City, Utah, are examined. Using {approx}860 h of combined ruby (0.694 {micro}m) lidar and midinfrared (9.5-11.5 {micro}m) radiometer data collected between 1992 and 1999 from visually identified cirrus clouds, the visible optical depths {tau} and infrared layer emittance epsilon of the varieties of midlatitude cirrus are characterized. The mean and median values for the cirrus sample are 0.75 {+-} 0.91 and 0.61 for {tau}, and 0.30 {+-} 0.22 and 0.25 for epsilon. Other scattering parameters studied are the visible extinction and infrared absorption coefficients, and their ratio, and the lidar backscatter-to-extinction ratio, which has a mean value of 0.041 sr{sup -1}. Differences among cirrus clouds generated by general synoptic (e.g., jet stream), thunderstorm anvil, and orographic mechanisms are found, reflecting basic cloud microphysical effects. The authors draw parameterizations in terms of midcloud temperature T{sub m} and physical cloud thickness {Delta}z for epsilon and {tau}: both macrophysical variables are needed to adequately address the impact of the adiabatic process on ice cloud content, which modulates radiative transfer as a function of temperature. For the total cirrus dataset, the authors find epsilon = 1 -exp [-8.5 x 10{sup -5} (T{sub m} + 80 C) {Delta}z]. These parameterizations, based on a uniquely comprehensive dataset, hold the potential for improving weather and climate model predictions, and satellite cloud property retrieval methods.

  10. Development of Satellite-based Climatology of Low-level Cloud and Fog in Mountain Terrain

    NASA Astrophysics Data System (ADS)

    Duan, Y.; Barros, A. P.

    2014-12-01

    The presence of orographic clouds and fog has major environmental and economic implications that the potential shift in the space-time distribution can effectively redistribute freshwater resources and threaten the sustainability of the ecology, geomorphology and hydrology of mountainous regions and adjacent basins. This includes the Southern Appalachian Mountains, which rely closely on the moisture input from fog, cap clouds and light rainfall, as well as cloud forests in the Andes with frequent occurrence of dense fog. However, the applicability of fog forecasting models becomes limited in regions of complex terrain. The motivation of this project is to develop a satellite-based hydroclimatology and physical parameterization of orographic low-level clouds and fog regimes in the Southern Appalachians using a general methodology that can be applied to mountainous regions elsewhere. An algorithm for the detection and extraction of stratus clouds and fog was developed using changes in vertical gradients of CPR reflectivity and liquid water products from almost 5-years of CLOUDSAT and SRTM terrain data. This population of low-level clouds and fog will be analyzed with GOES infrared and visible imagery, MODIS and CALIPSO products, and with airport cloud height and visibility records to expand the spatial coverage beyond narrow satellite sensor swaths. The climatology will be further developed through integration with results from WRF simulations for selected periods since the bulk of the PMM network has been in place (2008-present) to aid in defining meteorological and time-of-day constraints in the interpretation of simulated satellite radar reflectivity profiles. The overarching goal is to infer a representation of the diurnal cycle, seasonal and inter-annual variations of the vertical distribution of LWC and hydrometeors in orographic clouds and fog that vary spatially with landform toward developing a more general parameterization of seeder-feeder interactions in

  11. Aerosol climatology using a tunable spectral variability cloud screening of AERONET data

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Gobbi, Gian Paolo; Koren, Ilan

    2005-01-01

    Can cloud screening of an aerosol data set, affect the aerosol optical thickness (AOT) climatology? Aerosols, humidity and clouds are correlated. Therefore, rigorous cloud screening can systematically bias towards less cloudy conditions, underestimating the average AOT. Here, using AERONET data we show that systematic rejection of variable atmospheric optical conditions can generate such bias in the average AOT. Therefore we recommend (1) to introduce more powerful spectral variability cloud screening and (2) to change the philosophy behind present aerosol climatologies: Instead of systematically rejecting all cloud contaminations, we suggest to intentionally allow the presence of cloud contamination, estimate the statistical impact of the contamination and correct for it. The analysis, applied to 10 AERONET stations with approx. 4 years of data, shows almost no change for Rome (Italy), but up to a change in AOT of 0.12 in Beijing (PRC). Similar technique may be explored for satellite analysis, e.g. MODIS.

  12. The Effect of Moonlight on Observation of Cloud Cover at Night, and Application to Cloud Climatology.

    NASA Astrophysics Data System (ADS)

    Hahn, Carole J.; Warren, Stephen G.; London, Julius

    1995-05-01

    Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies based on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight.Ten years of nighttime weather observations from the Northern Hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6°, light from a partial moon at higher elevation, or twilight from the sun less than 9° below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon.The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is new found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans fair from the continents, particularly in summer. However, near-noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a few

  13. Comparisons of cloud ice mass content retrieved from the radar-infrared radiometer method with aircraft data during the second international satellite cloud climatology project regional experiment (FIRE-II)

    SciTech Connect

    Matrosov, S.Y. |; Heymsfield, A.J.; Kropfli, R.A.; Snider, J.B.

    1996-04-01

    Comparisons of remotely sensed meteorological parameters with in situ direct measurements always present a challenge. Matching sampling volumes is one of the main problems for such comparisons. Aircraft usually collect data when flying along a horizontal leg at a speed of about 100 m/sec (or even greater). The usual sampling time of 5 seconds provides an average horizontal resolution of the order of 500 m. Estimations of vertical profiles of cloud microphysical parameters from aircraft measurements are hampered by sampling a cloud at various altitudes at different times. This paper describes the accuracy of aircraft horizontal and vertical coordinates relative to the location of the ground-based instruments.

  14. Cloud forcing in Arctic polynyas: Climatology, parameterization, and modeling

    NASA Astrophysics Data System (ADS)

    Key, Erica

    Cloud and radiation data gathered in four polynyas across the Western Arctic span a decade of extreme environmental variability that culminated in the furthest retreat of sea ice cover on satellite record. These polynyas, oases of open water within the pack ice, are areas of intense surface exchange and serve as small-scale natural models of all active polar processes. Each of the studied polynyas is uniquely forced and maintained, resulting in an ensemble which representatively samples pan-Arctic variability. Cloud amount in each polynya, as analyzed to WMO standards by a meteorologist from time-lapse imagery collected using a hemispheric mirror, exceeded previous observational estimates of 80%. Calculations of surface cloud radiative forcing point to Arctic clouds' tendency toward scattering incoming shortwave radiation over re-emission of radiation in the longwave from cloud base. Sensitivity of this cloud forcing to variations in albedo, aerosol loading, and cloud microphysics, calculated with a polar-optimized radiative transfer model, indicate that small changes in snow and ice cover elicit stronger responses than heavy aerosol loading, changing particle effective radius, or liquid water content, especially at small solar zenith angles. Results obtained locally within polynyas are given regional relevance through the use of CASPR (Cloud and Surface Parameter Retrieval) algorithms and AVHRR Polar Pathfinder data.

  15. Climatology of cloud (radiative) parameters at two stations in Switzerland using hemispherical sky-cameras

    NASA Astrophysics Data System (ADS)

    Aebi, Christine; Gröbner, Julian; Kämpfer, Niklaus; Vuilleumier, Laurent

    2017-04-01

    Our study analyses climatologies of cloud fraction, cloud type and cloud radiative effect depending on different parameters at two stations in Switzerland. The calculations have been performed for shortwave (0.3 - 3 μm) and longwave (3 - 100 μm) radiation separately. Information about fractional cloud coverage and cloud type is automatically retrieved from images taken by visible all-sky cameras at the two stations Payerne (490 m asl) and Davos (1594 m asl) using a cloud detection algorithm developed by PMOD/WRC (Wacker et al., 2015). Radiation data are retrieved from pyranometers and pyrgeometers, the cloud base height from a ceilometer and IWV data from GPS measurements. Interestingly, Davos and Payerne show different trends in terms of cloud coverage and cloud fraction regarding seasonal variations. The absolute longwave cloud radiative effect (LCE) for low-level clouds and a cloud coverage of 8 octas has a median value between 61 and 72 Wm-2. It is shown that the fractional cloud coverage, the cloud base height (CBH) and integrated water vapour (IWV) all have an influence on the magnitude of the LCE and will be illustrated with key examples. The relative values of the shortwave cloud radiative effect (SCE) for low-level clouds and a cloud coverage of 8 octas are between -88 to -62 %. The SCE is also influenced by the latter parameters, but also if the sun is covered or not by clouds. At both stations situations of shortwave radiation cloud enhancements have been observed and will be discussed. Wacker S., J. Gröbner, C. Zysset, L. Diener, P. Tzoumanikas, A. Kazantzidis, L. Vuilleumier, R. Stöckli, S. Nyeki, and N. Kämpfer (2015) Cloud observations in Switzerland using hemispherical sky cameras, J. Geophys. Res. Atmos, 120, 695-707.

  16. Nimbus-7 global cloud climatology. I - Algorithms and validation

    NASA Technical Reports Server (NTRS)

    Stowe, L. L.; Wellemeyer, C. G.; Yeh, H. Y. M.; Eck, T. F.; Hwang, P. H.; Kyle, H. L.

    1988-01-01

    An improved version of the Nimbus-7 cloud retrieval algorithm was validated using data from Nimbus-7 Temperature Humidity Infrared Radiometer and Total Ozone Mapping Spectrometer to determine cloudiness parameters for the globe. Quantitative validation of total cloud amount was performed by comparing the algorithm results with estimates derived from GOES images and auxiliary meteorological data. The systematic errors of the Nimbus-7 total cloud-amount algorithm, relative to the GOES-derived estimates, were found to be less than 10 percent. The random errors of daily estimates ranged between 7 and 16 percent, day or night.

  17. Impact of deforestation in the Amazon basin on cloud climatology.

    PubMed

    Wang, Jingfeng; Chagnon, Frédéric J F; Williams, Earle R; Betts, Alan K; Renno, Nilton O; Machado, Luiz A T; Bisht, Gautam; Knox, Ryan; Bras, Rafael L

    2009-03-10

    Shallow clouds are prone to appear over deforested surfaces whereas deep clouds, much less frequent than shallow clouds, favor forested surfaces. Simultaneous atmospheric soundings at forest and pasture sites during the Rondonian Boundary Layer Experiment (RBLE-3) elucidate the physical mechanisms responsible for the observed correlation between clouds and land cover. We demonstrate that the atmospheric boundary layer over the forested areas is more unstable and characterized by larger values of the convective available potential energy (CAPE) due to greater humidity than that which is found over the deforested area. The shallow convection over the deforested areas is relatively more active than the deep convection over the forested areas. This greater activity results from a stronger lifting mechanism caused by mesoscale circulations driven by deforestation-induced heterogeneities in land cover.

  18. Empirical and modeled synoptic cloud climatology of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Newell, J. P.; Schweiger, A.; Crane, R. G.

    1986-01-01

    A set of cloud cover data were developed for the Arctic during the climatically important spring/early summer transition months. Parallel with the determination of mean monthly cloud conditions, data for different synoptic pressure patterns were also composited as a means of evaluating the role of synoptic variability on Arctic cloud regimes. In order to carry out this analysis, a synoptic classification scheme was developed for the Arctic using an objective typing procedure. A second major objective was to analyze model output of pressure fields and cloud parameters from a control run of the Goddard Institue for Space Studies climate model for the same area and to intercompare the synoptic climatatology of the model with that based on the observational data.

  19. The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset

    NASA Technical Reports Server (NTRS)

    Huffman, George J.; Adler, Robert F.; Arkin, Philip; Chang, Alfred; Ferraro, Ralph; Gruber, Arnold; Janowiak, John; McNab, Alan; Rudolf, Bruno; Schneider, Udo

    1997-01-01

    The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit -satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5 deg x 2.5 deg latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.

  20. The Global Precipitation Climatology Project (GPCP) combined precipitation dataset

    SciTech Connect

    Huffman, G.J.

    1997-01-01

    The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5{degrees} x 2.5{degrees} latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.

  1. Tennessee Valley Total and Cloud-to-Ground Lightning Climatology Comparison

    NASA Technical Reports Server (NTRS)

    Buechler, Dennis; Blakeslee, R. J.; Hall, J. M.; McCaul, E. W.

    2008-01-01

    The North Alabama Lightning Mapping Array (NALMA) has been in operation since 2001 and consists often VHF receivers deployed across northern Alabama. The NALMA locates sources of impulsive VHF radio signals from total lightning by accurately measuring the time that the signals arrive at the different receiving stations. The sources detected are then clustered into flashes by applying spatially and temporally constraints. This study examines the total lightning climatology of the region derived from NALMA and compares it to the cloud-to-ground (CG) climatology derived from the National Lightning Detection Network (NLDN) The presentation compares the total and CG lightning trends for monthly, daily, and hourly periods.

  2. Tennessee Valley Total and Cloud-to-Ground Lightning Climatology Comparison

    NASA Technical Reports Server (NTRS)

    Buechler, Dennis; Blakeslee, R. J.; Hall, J. M.; McCaul, E. W.

    2008-01-01

    The North Alabama Lightning Mapping Array (NALMA) has been in operation since 2001 and consists often VHF receivers deployed across northern Alabama. The NALMA locates sources of impulsive VHF radio signals from total lightning by accurately measuring the time that the signals arrive at the different receiving stations. The sources detected are then clustered into flashes by applying spatially and temporally constraints. This study examines the total lightning climatology of the region derived from NALMA and compares it to the cloud-to-ground (CG) climatology derived from the National Lightning Detection Network (NLDN) The presentation compares the total and CG lightning trends for monthly, daily, and hourly periods.

  3. The role of global cloud climatologies in validating numerical models

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN

    1992-01-01

    Global maps of the monthly mean net upward longwave radiation flux at the ocean surface were obtained for April, July, October 1985 and January 1986. These maps were produced by blending information obtained from a combination of general circulation model cloud radiative forcing fields, the top of the atmosphere cloud radiative forcing from ERBE and TOVS profiles and sea surface temperature on ISCCP C1 tapes. The fields are compatible with known meteorological regimes of atmospheric water vapor content and cloudiness. There is a vast area of high net upward longwave radiation flux (greater than 80/sq Wm) in the eastern Pacific Ocean throughout most of the year. Areas of low net upward longwave radiation flux ((less than 40/sq Wm) are the tropical convective regions and extra tropical regions that tend to have persistent low cloud cover.The technique used relies on General Circulation Model simulations and so is subject to some of the uncertainties associated with the model. However, all input information regarding temperature, moisture, and cloud cover is from satellite data having near global coverage. This feature of the procedure alone warrants its consideration for further use in compiling global maps of longwave radiation.

  4. Simple solar radiation modelling for different cloud types and climatologies

    NASA Astrophysics Data System (ADS)

    Badescu, Viorel; Dumitrescu, Alexandru

    2016-04-01

    The instantaneous Cloud Fraction Coverage (iCFC) and Cloud Type (iCTY) products of the Climate Monitoring Satellite Application Facility are used to develop simple relationships between solar global irradiance and cloud amount and types. Radiometric measurements from five Romanian weather stations are used. Solar radiation relationships are proposed for clear sky, overcast sky and cloudy sky. A procedure to average the iCTY data is proposed, and eight classes of averaged iCTY values are considered. Two procedures are used to define the overcast sky and two cloudy sky solar radiation models are considered. Overcast skies consisting of stratiform clouds (CTY classes 8 to 14) are the most challenging when solar radiation modelling is considered. The overcast sky models have lower accuracy at high irradiance values. The best cloudy sky model has relative root mean square error values ranging between 17.6 % (for CTY classes 1 to 4) and 67.6 % (for CTY classes 12 to 14). For most CTY classes, the model performs worse at intermediate irradiance values.

  5. The role of global cloud climatologies in validating numerical models

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN

    1991-01-01

    Reliable estimates of the components of the surface radiation budget are important in studies of ocean-atmosphere interaction, land-atmosphere interaction, ocean circulation and in the validation of radiation schemes used in climate models. The methods currently under consideration must necessarily make certain assumptions regarding both the presence of clouds and their vertical extent. Because of the uncertainties in assumed cloudiness, all these methods involve perhaps unacceptable uncertainties. Here, a theoretical framework that avoids the explicit computation of cloud fraction and the location of cloud base in estimating the surface longwave radiation is presented. Estimates of the global surface downward fluxes and the oceanic surface net upward fluxes were made for four months (April, July, October and January) in 1985 to 1986. These estimates are based on a relationship between cloud radiative forcing at the top of the atmosphere and the surface obtained from a general circulation model. The radiation code is the version used in the UCLA/GLA general circulation model (GCM). The longwave cloud radiative forcing at the top of the atmosphere as obtained from Earth Radiation Budget Experiment (ERBE) measurements is used to compute the forcing at the surface by means of the GCM-derived relationship. This, along with clear-sky fluxes from the computations, yield maps of the downward longwave fluxes and net upward longwave fluxes at the surface. The calculated results are discussed and analyzed. The results are consistent with current meteorological knowledge and explainable on the basis of previous theoretical and observational works; therefore, it can be concluded that this method is applicable as one of the ways to obtain the surface longwave radiation fields from currently available satellite data.

  6. LIVAS: a 3-D multi-wavelength aerosol/cloud climatology based on CALIPSO and EARLINET

    NASA Astrophysics Data System (ADS)

    Amiridis, V.; Marinou, E.; Tsekeri, A.; Wandinger, U.; Schwarz, A.; Giannakaki, E.; Mamouri, R.; Kokkalis, P.; Binietoglou, I.; Solomos, S.; Herekakis, T.; Kazadzis, S.; Gerasopoulos, E.; Balis, D.; Papayannis, A.; Kontoes, C.; Kourtidis, K.; Papagiannopoulos, N.; Mona, L.; Pappalardo, G.; Le Rille, O.; Ansmann, A.

    2015-01-01

    We present LIVAS, a 3-dimentional multi-wavelength global aerosol and cloud optical climatology, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. LIVAS database provides averaged profiles of aerosol optical properties for the potential space-borne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global climatology is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent spectral conversion factors for backscatter and extinction, derived from EARLINET ground-based measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversion factors are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO extinction and backscatter data correspondingly to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud climatology based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for space-borne lidar performance assessments. The final global climatology includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO data on a uniform grid of 1×1 degree with the original high vertical resolution of CALIPSO in order to ensure realistic simulations of the atmospheric variability in lidar end-to-end simulations.

  7. Estimating Climatological Bias Errors for the Global Precipitation Climatology Project (GPCP)

    NASA Technical Reports Server (NTRS)

    Adler, Robert; Gu, Guojun; Huffman, George

    2012-01-01

    A procedure is described to estimate bias errors for mean precipitation by using multiple estimates from different algorithms, satellite sources, and merged products. The Global Precipitation Climatology Project (GPCP) monthly product is used as a base precipitation estimate, with other input products included when they are within +/- 50% of the GPCP estimates on a zonal-mean basis (ocean and land separately). The standard deviation s of the included products is then taken to be the estimated systematic, or bias, error. The results allow one to examine monthly climatologies and the annual climatology, producing maps of estimated bias errors, zonal-mean errors, and estimated errors over large areas such as ocean and land for both the tropics and the globe. For ocean areas, where there is the largest question as to absolute magnitude of precipitation, the analysis shows spatial variations in the estimated bias errors, indicating areas where one should have more or less confidence in the mean precipitation estimates. In the tropics, relative bias error estimates (s/m, where m is the mean precipitation) over the eastern Pacific Ocean are as large as 20%, as compared with 10%-15% in the western Pacific part of the ITCZ. An examination of latitudinal differences over ocean clearly shows an increase in estimated bias error at higher latitudes, reaching up to 50%. Over land, the error estimates also locate regions of potential problems in the tropics and larger cold-season errors at high latitudes that are due to snow. An empirical technique to area average the gridded errors (s) is described that allows one to make error estimates for arbitrary areas and for the tropics and the globe (land and ocean separately, and combined). Over the tropics this calculation leads to a relative error estimate for tropical land and ocean combined of 7%, which is considered to be an upper bound because of the lack of sign-of-the-error canceling when integrating over different areas with a

  8. RAPTOR Transmissivity and Cloud Climatology Study. Final report

    SciTech Connect

    Eis, K.E.; Vonder Haar, T.H.; Forsythe, J.; Wong, Takmeng; Reinke, D.L.

    1993-01-01

    The RAPTOR Transmissivity Study (RTS) was funded by Lawrence Livermore National Laboratory (LLNL) under a sub contract to support the U.S. Army`s RAPTOR program. The intent of the study is to answer two questions: (1) What are the typical transmission levels of clouds as a function of target altitude for two locations and wavelengths of interest? (2) What is the probability that a cloud will intervene between sensor and target for a given target altitude, range, wavelength and location? This was addressed for Iraq and Korea. Answers to both questions are treated using existing software and data sources where possible due to the limited funding and scope of the contract.

  9. Cloud Climatology for Land Stations Worldwide, 1971-2009 (NDP-026D)

    DOE Data Explorer

    Hahn, C. J. [University of Arizona; Warren, S. G. [University of Washington; Eastman, R. [University of Washington

    2012-08-01

    Surface synoptic weather reports for 39 years have been processed to provide a climatology of clouds for each of over 5000 land-based weather stations with long periods of record both day and night. For each station, this digital archive includes: multi-year annual, seasonal and monthly averages for day and night separately; seasonal and monthly averages by year; averages for eight times per day; and analyses of the first harmonic for the annual and diurnal cycles. Averages are given for total cloud cover, clear-sky frequency, and 9 cloud types: 5 in the low level (fog, St, Sc, Cu, Cb), 3 in the middle level (Ns, As, Ac) and one in the high level (all cirriform clouds combined). Cloud amounts and frequencies of occurrence are given for all types. In addition, non-overlapped amounts are given for middle and high cloud types, and average base heights are given for low cloud types. Nighttime averages were obtained by using only those reports that met an "illuminance criterion" (i.e., made under adequate moonlight or twilight), thus making possible the determination of diurnal cycles and nighttime trends for cloud types.The authors have also produced an online, gridded atlas of the cloud observations contained in NDP-026D. The Online Cloud Atlas containing NDP-026D data is available via the University of Washington.

  10. Climatology and Formation of Tropical Midlevel Clouds at the Darwin ARM Site

    SciTech Connect

    Riihimaki, Laura D.; McFarlane, Sally A.; Comstock, Jennifer M.

    2012-10-01

    A 4-yr climatology of midlevel clouds is presented from vertically pointing cloud lidar and radar measurements at the Atmospheric Radiation Measurement Program (ARM) site at Darwin, Australia. Few studies exist of tropical midlevel clouds using a dataset of this length. Seventy percent of clouds with top heights between 4 and 8 km are less than 2 km thick. These thin layer clouds have a peak in cloud-top temperature around the melting level (0°C) and also a second peak around -12.5°C. The diurnal frequency of thin clouds is highest during the night and reaches a minimum around noon, consistent with variation caused by solar heating. Using a 1.5-yr subset of the observations, the authors found that thin clouds have a high probability of containing supercooled liquid water at low temperatures: ~20% of clouds at -30°C, ~50% of clouds at -20°C, and ~65% of clouds at -10°C contain supercooled liquid water. The authors hypothesize that thin midlevel clouds formed at the melting level are formed differently during active and break monsoon periods and test this over three monsoon seasons. A greater frequency of thin midlevel clouds are likely formed by increased condensation following the latent cooling of melting during active monsoon periods when stratiform precipitation is most frequent. This is supported by the high percentage (65%) of midlevel clouds with preceding stratiform precipitation and the high frequency of stable layers slightly warmer than 0°C. In the break monsoon, a distinct peak in the frequency of stable layers at 0°C matches the peak in thin midlevel cloudiness, consistent with detrainment from convection.

  11. MERIS albedo climatology for FRESCO+ O2 A-band cloud retrieval

    NASA Astrophysics Data System (ADS)

    Popp, C.; Wang, P.; Brunner, D.; Stammes, P.; Zhou, Y.; Grzegorski, M.

    2011-03-01

    A new global albedo climatology for Oxygen A-band cloud retrievals is presented. The climatology is based on MEdium Resolution Imaging Spectrometer (MERIS) Albedomap data and its favourable impact on the derivation of cloud fraction is demonstrated for the FRESCO+ (Fast Retrieval Scheme for Clouds from the Oxygen A-band) algorithm. To date, a relatively coarse resolution (1° × 1°) surface reflectance dataset from GOME (Global Ozone Monitoring Experiment) Lambert-equivalent reflectivity (LER) is used in FRESCO+. The GOME LER climatology does not account for the usually higher spatial resolution of UV/VIS instruments designed for trace gas remote sensing which introduces several artefacts, e.g. in regions with sharp spectral contrasts like coastlines or over bright surface targets. Therefore, MERIS black-sky albedo (BSA) data from the period October 2002 to October 2006 were aggregated to a grid of 0.25° × 0.25° for each month of the year and for different spectral channels. In contrary to other available surface reflectivity datasets, MERIS includes channels at 754 nm and 775 nm which are located close to the spectral windows required for O2 A-band cloud retrievals. The MERIS BSA in the near-infrared compares well to Moderate Resolution Imaging Spectroradiometer (MODIS) derived BSA with an average difference lower than 1% and a correlation coefficient of 0.98. However, when relating MERIS BSA to GOME LER a distinctly lower correlation (0.80) and enhanced scatter is found. Effective cloud fractions from two exemplary months (January and July 2006) of Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) data were subsequently derived with FRESCO+ and compared to those from the Heidelberg Iterative Cloud Retrieval Utilities (HICRU) algorithm. The MERIS climatology generally improves FRESCO+ effective cloud fractions. In particular small cloud fractions are in better agreement with HICRU. This is of importance for atmospheric trace gas

  12. Cloud Cover and Visibility Climatology for the Philippines

    DTIC Science & Technology

    1980-05-01

    USAF Uj ENVIRONMENTAL __ " TECHNICAL APPLICATIONS CENTERK SCOTT AIR FORCE BASE, ILLINOIS 62225 S6 10 089 REVIEW AND APPROVAL STATEMENT LYSAFETAC/PR-80...PROGRAm EL EMENt `PROJECT. TAS<ý US Air Force Environmental Technical AE OKUI UBR * Scott AFB, Illinois 62225 11. CONTROLLING OFFICE NAME AND ADDRESS...Aparri, Baguio, Borangan, Cagayan de Oro, Clark AB, Cebu , Daet, Davao, Dipolog, Duxnaquete, Hinatuan, Iloilo, Malaybalay, Manila, Masbate, Surigao, Vigan

  13. Satellite Studies of Cirrus Clouds for Project Fire

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Examine global cloud climatologies for evidence of human caused changes in cloud cover and their effect on the Earth's heat budget through radiative processes. Quantify climatological changes in global cloud cover and estimate their effect on the Earth's heat budget. Improve our knowledge of global cloud cover and its changes through the merging of several satellite data sets.

  14. MERIS albedo climatology for FRESCO+ O2 A-band cloud retrieval

    NASA Astrophysics Data System (ADS)

    Popp, C.; Wang, P.; Brunner, D.; Stammes, P.; Zhou, Y.; Grzegorski, M.

    2010-10-01

    A new global albedo climatology for Oxygen A-band cloud retrievals is presented. The climatology is based on MEdium Resolution Imaging Spectrometer (MERIS) Albedomap data and its favourable impact on the derivation of cloud fraction is demonstrated for the FRESCO+ (Fast Retrieval Scheme for Clouds from the Oxygen A-band) algorithm. To date, a relatively coarse resolution (1° × 1°) surface reflectance dataset from GOME (Global Ozone Monitoring Experiment) Lambert-equivalent reflectivity (LER) is used in FRESCO+. The GOME LER climatology does not account for the usually higher spatial resolution of UV/VIS instruments designed for trace gas remote sensing which introduces several artefacts, e.g. in regions with sharp spectral contrasts like coastlines or over bright surface targets. Therefore, MERIS black-sky albedo (BSA) data from the period October 2002 to October 2006 were aggregated to a grid of 0.25° × 0.25° for each month of the year and for different spectral channels. In contrary to other available surface reflectivity datasets, MERIS includes channels at 754 nm and 775 nm which are located close to the spectral windows required for O2 A-band cloud retrievals. The MERIS BSA in the near infrared compares well to Moderate Resolution Imaging Spectroradiometer (MODIS) derived BSA with an average difference lower than 1% and a correlation coefficient of 0.98. However, when relating MERIS BSA to GOME LER a distinctly lower correlation (0.80) and enhanced scatter is found. Effective cloud fractions from two exemplary months (January and July 2006) of Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) data were subsequently derived with FRESCO+ and compared to those from the Heidelberg Iterative Cloud Retrieval Utilities (HICRU) algorithm. The MERIS climatology generally improves FRESCO+ effective cloud fractions. In particular small cloud fractions are in better agreement with HICRU. This is of importance for atmospheric trace gas

  15. A multisatellite climatology of clouds, radiation, and precipitation in southern West Africa and comparison to climate models

    NASA Astrophysics Data System (ADS)

    Hill, Peter G.; Allan, Richard P.; Chiu, J. Christine; Stein, Thorwald H. M.

    2016-09-01

    Southern West Africa (SWA) has a large population that relies on highly variable monsoon rainfall, yet climate models show little consensus over projected precipitation in this region. Understanding of the current and future climate of SWA is further complicated by rapidly increasing anthropogenic emissions and a lack of surface observations. Using multiple satellite observations, the ERA-Interim reanalysis, and four climate models, we document the climatology of cloud, precipitation, and radiation over SWA in June-July, highlight discrepancies among satellite products, and identify shortcomings in climate models and ERA-Interim. Large differences exist between monthly mean cloud cover estimates from satellites, which range from 68 to 94%. In contrast, differences among satellite observations in top of atmosphere outgoing radiation and surface precipitation are smaller, with monthly means of about 230 W m-2 of longwave radiation, 145 W m-2 of shortwave radiation, and 5.87 mm d-1 of precipitation. Both ERA-Interim and the climate models show less total cloud cover than observations, mainly due to underestimating low cloud cover. Errors in cloud cover, along with uncertainty in surface albedo, lead to a large spread of outgoing shortwave radiation. Both ERA-Interim and the climate models also show signs of convection developing too early in the diurnal cycle, with associated errors in the diurnal cycles of precipitation and outgoing longwave radiation. Clouds, radiation, and precipitation are linked in an analysis of the regional energy budget, which shows that interannual variability of precipitation and dry static energy divergence are strongly linked.

  16. Climatology Study of Low-level Cloud and Fog in Mountain Terrain Using Satellite Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Duan, Yajuan; Barros, Ana P.

    2015-04-01

    The presence of orographic clouds and fog has major environmental and economic implications that the potential shift in the space-time distribution can effectively redistribute freshwater resources and threaten the sustainability of the ecology, geomorphology and hydrology of mountainous regions and adjacent basins. This includes the Southern Appalachian Mountains, which rely closely on the moisture input from fog, cap clouds and light rainfall, as well as cloud forests in the Andes with frequent occurrence of dense fog. However, the applicability of fog forecasting models becomes limited in regions of complex terrain. The motivation of this project is to develop a satellite-based hydroclimatology and physical parameterization of orographic low-level clouds and fog regimes in the Southern Appalachians using a general methodology that can be applied to mountainous regions elsewhere. An algorithm for the detection and extraction of stratus clouds and fog was developed using cloud base height product from 8-years of CALIPSO and CloudSat observations, and evaluated against ground-based measurements from ceilometers. This population of low-level clouds and fog will be analyzed with GOES infrared and visible imagery, MODIS products, and with airport cloud height and visibility records to expand the spatial coverage beyond narrow satellite sensor swaths. The climatology will be further developed through integration with results from WRF high-solution simulations for selected periods since the bulk of the PMM network has been in place (2008-present) to aid in defining meteorological and time-of-day constraints in the interpretation of simulated satellite profiles through a satellite-sensor simulator. A 4-day WRF simulation is performed at Pegion Basin in the Southern Appalachian Mountains with increasing horizontal (0.25 km grid spacing) and vertical (up to 80 sigma levels) resolution and evaluated against observations collected during the Integrated Precipitation and

  17. An eight-month climatology of marine stratocumulus cloud fraction, albedo, and integrated liquid water

    NASA Technical Reports Server (NTRS)

    Fairall, C. W.; Hare, J. E.; Snider, Jack B.

    1990-01-01

    As part of the FIRE/Extended Time Observations (ETO) program, extended time observations were made at San Nicolas Island (SNI) from March to October, 1987. Hourly averages of air temperature, relative humidity, wind speed and direction, solar irradiance, and downward longwave irradiance were recorded. The radiation sensors were standard Eppley pyranometers (shortwave) and pyrgeometers (longwave). The SNI data were processed in several ways to deduce properties of the stratocumulus covered marine boundary layer (MBL). For example, from the temperature and humidity the lifting condensation level, which is an estimate of the height of the cloud bottom, can be computed. A combination of longwave irradiance statistics can be used to estimate fractional cloud cover. An analysis technique used to estimate the integrated cloud liquid water content (W) and the cloud albedo from the measured solar irradiance is also described. In this approach, the cloud transmittance is computed by dividing the irradiance measured at some time by a clear sky value obtained at the same hour on a cloudless day. From the transmittance and the zenith angle, values of cloud albedo and W are computed using the radiative transfer parameterizations of Stephens (1978). These analysis algorithms were evaluated with 17 days of simultaneous and colocated mm-wave (20.6 and 31.65 GHz) radiometer measurements of W and lidar ceilometer measurements of cloud fraction and cloudbase height made during the FIRE IFO. The algorithms are then applied to the entire data set to produce a climatology of these cloud properties for the eight month period.

  18. Building a 15-Year Cloud Climatology using Lidar in Space Observations: CALIOP and CloudSat now, EarthCARE next.

    NASA Astrophysics Data System (ADS)

    Reverdy, M.; Chepfer, H.; Donovan, D. P.; Noel, V.; Marchand, R.; Cesana, G.; Hoareau, C.; Chiriaco, M.; Bastin, S.

    2014-12-01

    Today, the CALIOP lidar and CloudSat radar have collected more than seven years of observations, and willhopefully still operate in 2016, after the EarthCARE-ATLID/CPR launch. Lidars and Radars in space providecutting edge information on the detailed vertical structure of clouds: a key element for both the evaluation ofthe description of clouds in climate models, and the survey of the clouds inter-annual evolution in variousclimatic conditions (El Nino, variation of North Atlantic Oscillations, polar regions, etc). For this purpose,the observations collected by CALIOP and by ATLID as well as CloudSat and EarthCARE CPR need to bemerged into a long-term (15 years) cloud climatology. Here, we examine the possibility of building such a climatology, with the aim of defining its accuracy andrelevance for cloud inter-annual studies. We examine the differences between the instruments (wavelengths,satellite's altitudes, telescope fields of view, multiple scattering processes, spatial resolutions) and theirability to detect the same clouds consistently. Then, we define a set of cloud detection thresholds for ATLID,CALIOP, CloudSat and EarthCARE-CPR and test against synthetic cloud scenes (cirrus and shallowcumulus) over small areas (about 200km) produced by a lidar and radar instrument simulator (ECSIM)running on Large Eddy Simulations. Doing so, we verify that the fourth instruments will be able to detect thesame clouds despite their differences (e.g. their sensitivities to noise). Finally, we use the COSP lidar andradar simulator to predict the global scale cloud cover that ATLID, CALIOP, CloudSat and EarthCARE CPRwould observe if they were overflying the same atmosphere predicted by a GCM. Our results suggest that amerged CALIOP/ATLID and CloudSat/CPR cloud climatology could be to be useful for clouds inter-annualstudies, if the post-launch sensitivity of EarthCARE instruments is in line with what is predicted today.

  19. Arctic cloudiness - Comparison of ISCCP-C2 and Nimbus-7 satellite-derived cloud products with a surface-based cloud climatology

    NASA Technical Reports Server (NTRS)

    Schweiger, Axel J.; Key, Jeffrey R.

    1992-01-01

    One surface-based and two satellite arctic cloud climatologies are compared in terms of the annual cycle and spatial patterns of total monthly cloud amounts. Additionally, amounts and spatial patterns of low, middle, and high cloud type are compared. The surface-based dataset is for the years 1951-81, while the satellite-based data are for 1979-85 and 1983-86. The satellite cloud amounts are generally 5-35 percent less than the surface observations over the entire Arctic. However, regional differences may be as high as 45 percent. During July the surface-based cloud amounts for the central Arctic are about 40 percent greater than the satellite-based, but only 10 percent greater in the Norwegian Sea area. Surprisingly, (ISCCP) cloud climatology and surface observations agree better during winter than during summer. Possible reasons for these differences are discussed.

  20. Arctic cloudiness - Comparison of ISCCP-C2 and Nimbus-7 satellite-derived cloud products with a surface-based cloud climatology

    NASA Technical Reports Server (NTRS)

    Schweiger, Axel J.; Key, Jeffrey R.

    1992-01-01

    One surface-based and two satellite arctic cloud climatologies are compared in terms of the annual cycle and spatial patterns of total monthly cloud amounts. Additionally, amounts and spatial patterns of low, middle, and high cloud type are compared. The surface-based dataset is for the years 1951-81, while the satellite-based data are for 1979-85 and 1983-86. The satellite cloud amounts are generally 5-35 percent less than the surface observations over the entire Arctic. However, regional differences may be as high as 45 percent. During July the surface-based cloud amounts for the central Arctic are about 40 percent greater than the satellite-based, but only 10 percent greater in the Norwegian Sea area. Surprisingly, (ISCCP) cloud climatology and surface observations agree better during winter than during summer. Possible reasons for these differences are discussed.

  1. High Resolution Hydro-climatological Projections for Western Canada

    NASA Astrophysics Data System (ADS)

    Erler, Andre Richard

    Accurate identification of the impact of global warming on water resources and hydro-climatic extremes represents a significant challenge to the understanding of climate change on the regional scale. Here an analysis of hydro-climatic changes in western Canada is presented, with specific focus on the Fraser and Athabasca River basins and on changes in hydro-climatic extremes. The analysis is based on a suite of simulations designed to characterize internal variability, as well as model uncertainty. A small ensemble of Community Earth System Model version 1 (CESM1) simulations was employed to generate global climate projections, which were downscaled to 10 km resolution using the Weather Research and Forecasting model (WRF V3.4.1) with several sets of physical parameterizations. Downscaling was performed for a historical validation period and a mid- and end-21st-century projection period, using the RCP8.5 greenhouse gas trajectory. Daily station observations and monthly gridded datasets were used for validation. Changes in hydro-climatic extremes are characterized using Extreme Value Analysis. A novel method of aggregating data from climatologically similar stations was employed to increase the statistical power of the analysis. Changes in mean and extreme precipitation are found to differ strongly between seasons and regions, but (relative) changes in extremes generally follow changes in the (seasonal) mean. At the end of the 21st century, precipitation and precipitation extremes are projected to increase by 30% at the coast in fall and land-inwards in winter, while the projected increase in summer precipitation is smaller and changes in extremes are often not statistically significant. Reasons for the differences between seasons, the role of precipitation recycling in atmospheric water transport, and the sensitivity to physics parameterizations are discussed. Major changes are projected for the Fraser River basin, including earlier snowmelt and a 50% reduction in

  2. The NASA Energy and Water Cycle Climatology (NEWCC) Integration Project

    NASA Astrophysics Data System (ADS)

    Schlosser, C. A.; Lin, B.; NEWCC Team

    2008-05-01

    To date, a truly self-consistent, quantitative description of the Earth's global water and energy cycles, based on the highest quality, independently-observed pieces of information that decipher each of the key storage terms, fluxes, and pathways has been elusive. Such a data compilation of adequate climate quality is of vital interest and an ultimate scientific need of the global observation, modeling, and prediction community. To meet this need, we present results from the first phase of a NASA Energy and Water Cycle Climatology (NEWCC) Integration Project, a collaborative effort whose aim is to construct a defensible, self-consistent, long-term climatology of the global energy and water cycles. Our working hypothesis is that an observationally-based estimate of water and energy fluxes and storages, derived from focused and independently observed components of these cycles, can be balanced and provide useful characterizations and evaluation data for climate prediction and predictability studies. The NEWCC team members are actively involved in key facets of this observational arena, and thus for the first phase of NEWCC, we bring together state-of-the-art, (predominantly) satellite-based observations that include: precipitation, ocean and land evaporation, runoff, atmospheric water storage, ocean and land storage changes, atmospheric transport, radiation, latent and sensible heat fluxes, and subsequently hope to include explicit snow/ice information, such as snow water equivalent and ice mass changes. Our current efforts focus on the period spanning the years 2003 to 2005, for which the most recent and highest-quality satellite-based information is available for all the aforementioned quantities. We present an assessment of the ability of these observational datasets to satisfy the water and energy budgets and the degree to which they show consistency in their mean annual cycles as well as geospatial variability. In doing so, we will highlight, where possible, the

  3. Building a 13 to 16 years cloud climatology using lidar in space observations: CALIOP now, ATLID next

    NASA Astrophysics Data System (ADS)

    Reverdy, M.; Chepfer, H.; Donovan, D. P.; Noel, V.; Cesana, G.; Hoareau, C.; Chiriaco, M.; Bastin, S.

    2013-12-01

    Today, the CALIOP lidar has collected more than seven years of observations, and will hopefully still operate in 2016, after the EarthCare/ATLID lidar launch. Lidars in space provide cutting edge information on the detailed vertical structure of clouds: a key element for both the evaluation of the description of clouds in climate models, and the survey of the clouds inter-annual evolution in various climatic conditions: El Nino, variation of North Atlantic Oscillations, polar regions, etc. For this purpose, the observations collected by CALIOP and by ATLID need to be merged into a long-term (13 to 16 years) cloud climatology. Here, we examine the possibility of building such a climatology, with the aim of defining its accuracy and relevance for cloud inter-annual studies. We examined the differences between the two instruments (wavelengths, satellite's altitudes, telescope fields of view, multiple scattering processes, spatial resolutions) and their ability to detect the same clouds consistently. Then, we defined a set of cloud detection thresholds for ATLID and CALIOP, and tested against synthetic cloud scenes (cirrus and shallow cumulus) over small areas (about 200km) produced by a lidar instrument simulator (ECSIM) running on Large Eddy Simulations. Doing so, we verify that CALIOP and ATLID will be able to detect the same clouds despite their differences (e.g. their sensitivities to noise). Finally, we used the COSP lidar simulator to predict the global scale cloud cover that ATLID and CALIOP would observe if they were overflying the same atmosphere predicted by a GCM. As a consequence, a merged CALIOP/ATLID cloud climatology is likely to be useful for clouds inter-annual studies, if the post-launch sensitivity of ATLID is in line with what is predicted today.

  4. Partitioning the LIS/OTD Lightning Climatological Dataset into Separate Ground and Cloud Flash Distributions

    NASA Technical Reports Server (NTRS)

    Koshak, W. J.; Solarkiewicz, R. J.

    2009-01-01

    Presently, it is not well understood how to best model nitrogen oxides (NOx) emissions from lightning because lightning is highly variable. Peak current, channel length, channel altitude, stroke multiplicity, and the number of flashes that occur in a particular region (i.e., flash density) all influence the amount of lightning NOx produced. Moreover, these 5 variables are not the same for ground and cloud flashes; e.g., cloud flashes normally have lower peak currents, higher altitudes, and higher flash densities than ground flashes [see (Koshak, 2009) for additional details]. Because the existing satellite observations of lightning (Fig. 1) from the Lightning Imaging Sensor/Optical Transient Detector (LIS/OTD) do not distinguish between ground and cloud fashes, which produce different amounts of NOx, it is very difficult to accurately account for the regional/global production of lightning NOx. Hence, the ability to partition the LIS/OTD lightning climatology into separate ground and cloud flash distributions would substantially benefit the atmospheric chemistry modeling community. NOx indirectly influences climate because it controls the concentration of ozone and hydroxyl radicals in the atmosphere. The importance of lightning-produced NOx is empasized throughout the scientific literature (see for example, Huntrieser et al. 1998). In fact, lightning is the most important NOx source in the upper troposphere with a global production rate estimated to vary between 2 and 20 Tg (N)yr(sup -1) (Lee et al., 1997), with more recent estimates of about 6 Tg(N)yr(sup -1) (Martin et al., 2007). In order to make accurate predictions, global chemistry/climate models (as well as regional air quality modells) must more accurately account for the effects of lightning NOx. In particular, the NASA Goddard Institute for Space Studies (GISS) Model E (Schmidt et al., 2005) and the GEOS-CHEM global chemical transport model (Bey et al., 2001) would each benefit from a partitioning of the

  5. The Climatology of Polar Mesospheric Clouds From the Student Nitric Oxide Explorer

    NASA Astrophysics Data System (ADS)

    Bailey, S. M.; Thomas, G. E.; Merkel, A. W.

    2001-05-01

    Polar Mesospheric Clouds (PMCs) are a high latitude phenomenon known to occur at altitudes near 83 km at times near the summer solstice, and are related to the phenomenon of Noctilucent Clouds (NLCs). The first recorded siting of an NLC occurred in 1885 and there is evidence that the frequency of occurrence of NLCs is increasing, suggesting long term change in the mesosphere. The first climatology of PMCs was derived from observations by the Solar Mesospheric Explorer (SME) made during 1981 through 1986. SME observations showed seasonal variations with a typical PMC season lasting from approximately 90 days beginning 21 days before summer solstice. The Student Nitric Oxide Explorer (SNOE), like SME, observes the Earth's UV limb radiance and thus also observes PMCs. The instrumentation on SNOE and SME are nearly identical making the observations comparable. SNOE was launched on February 27, 1998; thus, the combination of SNOE and SME measurements cover a span of nearly two decades. To date, SNOE has observed three northern and three southern PMC seasons. In this talk we will present the algorithms for determining PMC scattering properties from the background limb radiance. We will present the derived rates of occurrence of PMCs from the SNOE measurements, and we will show how the variation of cloud brightness and latitudinal extent vary through the season. These results will be compared to those from SME.

  6. Estimation of polar stratospheric cloud infrared extinction climatology using visible satellite observations

    NASA Technical Reports Server (NTRS)

    Pitts, Michael C.; Thomason, Larry W.

    1995-01-01

    Polar stratospheric clouds (PSC's) provide surfaces for heterogeneous processes which can dramatically alter the normal partitioning of odd nitrogen and chlorine families in the winter polar stratospheres, setting up conditions for significant ozone depletion as manifested in the springtime Antarctic ozone hole. The spatial and temporal distribution of PSC's is important for parameterizing PSC occurrence in multidimensional photochemical models whose use is essential for fully understanding observed Antarctic ozone losses as well as for accessing the possibility of a similar phemonenon occurring in the future in the Arctic. The Stratospheric Aerosol Measurement (SAM) 2 sensor, a single-channel (1mu m) photometer launched into a Sun-synchronous orbit aboard the Nimbus 7 satellite in October 1978, provided a unique database to establish the climatology of PSC's. Poole and Pitts (1994) used the record of high-latitude aerosol extinction obtained by SAM II from 1979-1989 to establish the climatology of PSC occurrences in the Arctic and Antarctic. Unfortunately, little information about PSC composition or type was detectable from the single-wavelength SAM II data.

  7. Shuttle landing facility cloud cover study: Climatological analysis and two tenths cloud cover rule evaluation

    NASA Technical Reports Server (NTRS)

    Atchison, Michael K.; Schumann, Robin; Taylor, Greg; Warburton, John; Wheeler, Mark; Yersavich, Ann

    1993-01-01

    The two-tenths cloud cover rule in effect for all End Of Mission (EOM) STS landings at the Kennedy Space Center (KSC) states: 'for scattered cloud layers below 10,000 feet, cloud cover must be observed to be less than or equal to 0.2 at the de-orbit burn go/no-go decision time (approximately 90 minutes before landing time)'. This rule was designed to protect against a ceiling (below 10,000 feet) developing unexpectedly within the next 90 minutes (i.e., after the de-orbit burn decision and before landing). The Applied Meteorological Unit (AMU) developed and analyzed a database of cloud cover amounts and weather conditions at the Shuttle Landing Facility for a five-year (1986-1990) period. The data indicate the best time to land the shuttle at KSC is during the summer while the worst time is during the winter. The analysis also shows the highest frequency of landing opportunities occurs for the 0100-0600 UTC and 1300-1600 UTC time periods. The worst time of the day to land a shuttle is near sunrise and during the afternoon. An evaluation of the two-tenths cloud cover rule for most data categorizations has shown that there is a significant difference in the proportions of weather violations one and two hours subsequent to initial conditions of 0.2 and 0.3 cloud cover. However, for May, Oct., 700 mb northerly wind category, 1500 UTC category, and 1600 UTC category there is some evidence that the 0.2 cloud cover rule may be overly conservative. This possibility requires further investigation. As a result of these analyses, the AMU developed nomograms to help the Spaceflight Meteorological Group (SMG) and the Cape Canaveral Forecast Facility (CCFF) forecast cloud cover for EOM and Return to Launch Site (RTLS) at KSC. Future work will include updating the two tenths database, further analysis of the data for several categorizations, and developing a proof of concept artificial neural network to provide forecast guidance of weather constraint violations for shuttle

  8. Effects of Climatological Model Biases on the Projection of Tropical Climate Change

    NASA Astrophysics Data System (ADS)

    Xie, S. P.; Zhou, Z. Q.

    2015-12-01

    Climate models suffer from long-standing biases including the double intertropical convergence zone (ITCZ) problem and the excessive westward extension of the equatorial Pacific cold tongue. An atmospheric general circulation model is used to investigate how model biases in the mean state affect the projection of tropical climate change. The model is forced with a pattern of sea surface temperature (SST) increase derived from a coupled simulation of global warming but uses an SST climatology derived from either observations or a coupled historical simulation. The comparison of the experiments reveals that the climatological biases have important impacts on projected changes in the tropics. Specifically, during February-April when the climatological ITCZ displaces spuriously into the Southern Hemisphere, the model overestimates (underestimates) the projected rainfall increase in the warmer climate south (north) of the equator over the eastern Pacific. Furthermore, the global warming-induced Walker circulation slowdown is biased weak in the projection using coupled model climatology, suggesting that the projection of the reduced equatorial Pacific trades may also be under-estimated. This is related to the bias that the climatological Walker circulation is too weak in the model, which is in turn due to too weak mean SST gradient in the zonal direction. Our results highlight the importance of improving the climatological simulation for more reliable projections of regional climate change.

  9. Downward solar global irradiance at the surface in São Paulo city - The climatological effects of aerosol and clouds

    NASA Astrophysics Data System (ADS)

    Yamasoe, M. A.; Rosário, N. M. E.; Barros, K. M.

    2017-01-01

    We analyzed the variability of downward solar irradiance reaching the surface at São Paulo city, Brazil, and estimated the climatological aerosol and cloud radiative effects. Eleven years of irradiance were analyzed, from 2005 to 2015. To distinguish the aerosol from the cloud effect, the radiative transfer code LibRadtran was used to calculate downward solar irradiance. Two runs were performed, one considering only ozone and water vapor daily variability, with AOD set to zero and the second allowing the three variables to change, according to mean climatological values. The difference of the 24 h mean irradiance calculated with and without aerosol resulted in the shortwave aerosol direct radiative effect, while the difference between the measured and calculated, including the aerosol, represented the cloud effect. Results showed that, climatologically, clouds can be 4 times more effective than aerosols. The cloud shortwave radiative effect presented a maximum reduction of about -170 W m-2 in January and a minimum in July, of -37 W m-2. The aerosol direct radiative effect was maximum in spring, when the transport of smoke from the Amazon and central parts of South America is frequent toward São Paulo. Around mid-September, the 24 h radiative effect due to aerosol only was estimated to be -50 W m-2. Throughout the rest of the year, the mean aerosol effect was around -20 W m-2 and was attributed to local urban sources. The effect of the cloud fraction on the cloud modification factor, defined as the ratio of all-sky irradiation to cloudless sky irradiation, showed dependence on the cloud height. Low clouds presented the highest impact while the presence of high clouds only almost did not affect solar transmittance, even in overcast conditions.

  10. Climatological and radiative properties of midlatitude cirrus clouds derived by automatic evaluation of lidar measurements

    NASA Astrophysics Data System (ADS)

    Kienast-Sjögren, Erika; Rolf, Christian; Seifert, Patric; Krieger, Ulrich K.; Luo, Bei P.; Krämer, Martina; Peter, Thomas

    2016-06-01

    Cirrus, i.e., high, thin clouds that are fully glaciated, play an important role in the Earth's radiation budget as they interact with both long- and shortwave radiation and affect the water vapor budget of the upper troposphere and stratosphere. Here, we present a climatology of midlatitude cirrus clouds measured with the same type of ground-based lidar at three midlatitude research stations: at the Swiss high alpine Jungfraujoch station (3580 m a.s.l.), in Zürich (Switzerland, 510 m a.s.l.), and in Jülich (Germany, 100 m a.s.l.). The analysis is based on 13 000 h of measurements from 2010 to 2014. To automatically evaluate this extensive data set, we have developed the Fast LIdar Cirrus Algorithm (FLICA), which combines a pixel-based cloud-detection scheme with the classic lidar evaluation techniques. We find mean cirrus optical depths of 0.12 on Jungfraujoch and of 0.14 and 0.17 in Zürich and Jülich, respectively. Above Jungfraujoch, subvisible cirrus clouds (τ < 0.03) have been observed during 6 % of the observation time, whereas above Zürich and Jülich fewer clouds of that type were observed. Cirrus have been observed up to altitudes of 14.4 km a.s.l. above Jungfraujoch, whereas they have only been observed to about 1 km lower at the other stations. These features highlight the advantage of the high-altitude station Jungfraujoch, which is often in the free troposphere above the polluted boundary layer, thus enabling lidar measurements of thinner and higher clouds. In addition, the measurements suggest a change in cloud morphology at Jungfraujoch above ˜ 13 km, possibly because high particle number densities form in the observed cirrus clouds, when many ice crystals nucleate in the high supersaturations following rapid uplifts in lee waves above mountainous terrain. The retrieved optical properties are used as input for a radiative transfer model to estimate the net cloud radiative forcing, CRFNET, for the analyzed cirrus clouds. All cirrus detected

  11. Climatological data for clouds over the globe from surface observations, 1982--1991: The total cloud edition

    SciTech Connect

    Hahn, C.J.; Warren, S.G.; London, J.

    1994-10-01

    Routine, surface synoptic weather reports from ships and land stations over the entire globe, for the ten-year period December 1981 through November 1991, were processed for total cloud cover and the frequencies of occurrence of clear sky, precipitation, and sky-obscured due to fog. Archived data, consisting of various annual, seasonal and monthly averages, are provided in grid boxes that are typically 2.5{degrees} {times} 2.5{degrees} for land and 5{degrees} {times} 5{degrees} for ocean. Day and nighttime averages are also given separately for each season. Several derived quantities, such as interannual variations and annual and diurnal harmonics, are provided as well. This data set incorporates an improved representation of nighttime cloudiness by utilizing only those nighttime observations for which the illuminance due to moonlight exceeds a specified threshold. This reduction in the night-detection bias increases the computed global average total cloud cover by about 2%. The impact on computed diurnal cycles is even greater, particularly over the oceans where is found, in contrast to previous surface-based climatologies, that cloudiness is often greater at night than during the day.

  12. A Climatology of Polar Stratospheric Cloud Types by MIPAS-Envisat

    NASA Astrophysics Data System (ADS)

    Spang, Reinhold; Hoffmann, Lars; Griessbach, Sabine; Orr, Andrew; Höpfner, Michael; Müller, Rolf

    2015-04-01

    For Chemistry Climate Models (CCM) it is still a challenging task to properly represent the evolution of the polar vortices over the entire winter season. The models usually do not include comprehensive microphysical modules to evolve the formation of different types of polar stratospheric clouds (PSC) over the winter. Consequently, predictions on the development and recovery of the future ozone hole have relatively large uncertainties. A climatological record of hemispheric measurement of PSC types could help to better validate and improve the PSC schemes in CCMs. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument onboard the ESA Envisat satellite operated from July 2002 to April 2012. The infra-red limb emission measurements compile a unique dataset of day and night measurements of polar stratospheric clouds up to the poles. From the spectral measurements in the 4.15-14.6 microns range it is possible to select a number of atmospheric window regions and spectral signatures to classify PSC cloud types like nitric acid hydrates, sulfuric ternary solution droplets, and ice particles. The cloud detection sensitivity is similar to space borne lidars, but MIPAS adds complementary information due to its different measurement technique (limb instead of nadir) and wavelength region. Here we will describe a new classification method for PSCs based on the combination of multiple brightness temperature differences (BTD) and colour ratios. Probability density functions (PDF) of the MIPAS measurements in conjunction with a database of radiative transfer model calculations of realistic PSC particle size distributions enable the definition of regions attributed to specific or mixed types clouds. Applying a naive bias classifier for independent criteria to all defined classes in four 2D PDF distributions, it is possible to assign the most likely PSC type to any measured cloud spectrum. Statistical Monte Carlo test have been applied to quantify

  13. A 6-year climatology of cloud occurrence frequency from Stratospheric Aerosol and Gas Experiment II observations (1985-1990)

    NASA Astrophysics Data System (ADS)

    Wang, Pi-Huan; Minnis, Patrick; McCormick, M. Patrick; Kent, Geoffrey S.; Skeens, Kristi M.

    1996-12-01

    A 6-year climatology of subvisual and opaque cloud occurrence frequencies is established using observations from the Stratospheric Aerosol and Gas Experiment (SAGE) II between 1985 and 1990. The subvisual clouds are observed mostly at high altitudes near the tropopause. The opaque clouds terminate the profiling, reducing the measurement frequency of the SAGE II instrument in the troposphere. With its 1-km vertical resolution, the climatology shows many interesting features, including (1) the seasonal expansion and migration behavior of the subvisual and opaque cloud systems; (2) the association of the zonal mean cloud frequency distributions with the tropospheric mean circulation (Hadley and Ferrel cells); (3) the tropical cloud occurrence that follows the equatorial circulation, including the Walker circulation over the Pacific Ocean; and (4) the overall higher cloud occurrence in the northern hemisphere than in the southern hemisphere. The radiative impact of subvisual clouds is estimated to be a 1-W m-2 reduction in outgoing longwave radiation. The maximum overall effect is a net positive cloud forcing of 0.5-1 W m-2 in the tropics. During the 1987 El Niño-Southern Oscillation (ENSO), cloud frequency was generally enhanced in the tropics and midlatitudes and reduced in the subtropics and high latitudes. The present study shows a distinct negative correlation between the high-altitude cloud occurrence and the lower stratospheric water vapor mixing ratio in the tropics, providing intrinsic evidence on the delicate connection between the stratospheric-tropospheric exchange and dehydration processes and the high-altitude cloud activities.

  14. A CloudSat Perspective on the Cloud Climatology and Its Association with Aerosol Perturbations in the Vertical over Eastern China

    NASA Astrophysics Data System (ADS)

    Chen, T.; Guo, J.; Li, Z.; Zhao, C.

    2016-12-01

    Many efforts have been taken to investigate aerosol-cloud interactions from space, but only a few studies have examined the response of vertical cloud structure to aerosol perturbations. Three-dimensional cloud climatologies of eight different cloud types identified from the CloudSat Level 2 cloud product during the warm season (May-September) in 2008-10 over eastern China were first generated and analyzed. Using visibility as a proxy for cloud condensation nuclei, in combination with satellite-observed radar reflectivity, normalized contoured frequency by altitude diagrams of the differences in cloud radar reflectivity Z profiles under polluted and clean conditions were constructed. For shallow cumulus clouds (shallow Cu) Z tends to be inhibited, and it is enhanced in the upper layers for deep cumulus (deep Cu), nimbostratus (Ns), and deep convective clouds (DCC) under polluted conditions. Overall, analyses of the modified center of gravity (MCOG) and cloud-top height (CTH) also point to a similar aerosol effect, except for the nonsignificant changes in MCOGs and CTHs in deep Cu. The impacts of environmental factors such as lower tropospheric stability and vertical velocity are also discussed for these types of clouds. Although consistent aerosol-induced elevations in MCOGs and CTHs for Ns and DCC clouds are observed, the effect of meteorology cannot be completely ruled out, which merits further analysis.

  15. Quantifying the climatological cloud-free direct radiative forcing of aerosol over the Red Sea

    NASA Astrophysics Data System (ADS)

    Brindley, Helen; Osipov, Serega; Bantges, Richard; Smirnov, Alexander; Banks, Jamie; Levy, Robert; Prakash, P.-Jish; Stenchikov, Georgiy

    2015-04-01

    A combination of ground-based and satellite observations are used, in conjunction with column radiative transfer modelling, to assess the climatological aerosol loading and quantify its corresponding cloud-free direct radiative forcing (DRF) over the Red Sea. While there have been campaigns designed to probe aerosol-climate interactions over much of the world, relatively little attention has been paid to this region. Because of the remoteness of the area, satellite retrievals provide a crucial tool for assessing aerosol loading over the Sea. However, agreement between aerosol properties inferred from measurements from different instruments, and even in some cases from the same measurements using different retrieval algorithms can be poor, particularly in the case of mineral dust. Ground based measurements which can be used to evaluate retrievals are thus highly desirable. Here we take advantage of ship-based sun-photometer micro-tops observations gathered from a series of cruises which took place across the Red Sea during 2011 and 2013. To our knowledge these data represent the first set of detailed aerosol measurements from the Sea. They thus provide a unique opportunity to assess the performance of satellite retrieval algorithms in this region. Initially two aerosol optical depth (AOD) retrieval algorithms developed for the MODerate Resolution Imaging Spectroradiometer (MODIS) and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are evaluated via comparison with the co-located cruise observations. These show excellent agreement, with correlations typically better than 0.9 and very small root-mean-square and bias differences. Calculations of radiative fluxes and DRF along one of the cruises using the observed aerosol and meteorological conditions also show good agreement with co-located estimates from the Geostationary Earth Radiation Budget (GERB) instrument if the aerosol asymmetry parameter is adjusted to account for the presence of large

  16. Satellite-based climatology of low-level continental clouds in southern West Africa during the summer monsoon season

    NASA Astrophysics Data System (ADS)

    Linden, Roderick; Fink, Andreas H.; Redl, Robert

    2015-02-01

    Synoptic observations and various satellite products have been utilized for computing climatologies of low-level stratus over southern West Africa for the wet monsoon seasons July-September of 2006-2011. Previous studies found inconsistencies between satellite cloud products; climate models often fail to reproduce the extensive stratus decks. Therefore, a better observational reference and an understanding of its limitations are urgently needed to better validate models. Most detailed information of the spatiotemporal characteristics of low-level clouds was obtained from two Meteosat Second Generation (MSG) satellite-based data sets. However, CALIPSO and CloudSat cross sections of cloud occurrence frequency suggest that both MSG products underestimate the low-level cloudiness over Nigeria due to shielding by abundant upper level and midlevel clouds and reveal that the stratus is lower over the continent than over the ocean. The Terra Multiangle Imaging Spectroradiometer product appears to overestimate the morning extent of low-level clouds. The climatology presented here shows that the zone of abundant low-level stratiform clouds is at its diurnal minimum south of 6-7°N around sunset (~1800 UTC). Thereafter, it starts to spread inland and reaches its maximum northward extent of 10-11°N between 0900 and 1000 UTC. The maximum affected area is approximately 800,000 km2. After about 1000 UTC, the northern boundary gets fragmented due to the breakup of stratus decks into fair-weather cumuli. The stratus is most frequent around Cape Palmas, over Ivory Coast, and at the windward sides of the Mampong Range (Ghana) and Oshogbo Hills (Nigeria).

  17. Satellite-based climatology of low-level continental clouds in southern West Africa during the summer monsoon season

    NASA Astrophysics Data System (ADS)

    van der Linden, Roderick; Fink, Andreas H.; Redl, Robert

    2015-02-01

    Synoptic observations and various satellite products have been utilized for computing climatologies of low-level stratus over southern West Africa for the wet monsoon seasons July-September of 2006-2011. Previous studies found inconsistencies between satellite cloud products; climate models often fail to reproduce the extensive stratus decks. Therefore, a better observational reference and an understanding of its limitations are urgently needed to better validate models. Most detailed information of the spatiotemporal characteristics of low-level clouds was obtained from two Meteosat Second Generation (MSG) satellite-based data sets. However, CALIPSO and CloudSat cross sections of cloud occurrence frequency suggest that both MSG products underestimate the low-level cloudiness over Nigeria due to shielding by abundant upper level and midlevel clouds and reveal that the stratus is lower over the continent than over the ocean. The Terra Multiangle Imaging Spectroradiometer product appears to overestimate the morning extent of low-level clouds. The climatology presented here shows that the zone of abundant low-level stratiform clouds is at its diurnal minimum south of 6-7°N around sunset ( 1800 UTC). Thereafter, it starts to spread inland and reaches its maximum northward extent of 10-11°N between 0900 and 1000 UTC. The maximum affected area is approximately 800,000 km2. After about 1000 UTC, the northern boundary gets fragmented due to the breakup of stratus decks into fair-weather cumuli. The stratus is most frequent around Cape Palmas, over Ivory Coast, and at the windward sides of the Mampong Range (Ghana) and Oshogbo Hills (Nigeria).

  18. A 3-Year Climatology of Cloud and Radiative Properties Derived from GOES-8 Data Over the Southern Great Plains

    NASA Technical Reports Server (NTRS)

    Khaiyer, M. M.; Rapp, A. D.; Doelling, D. R.; Nordeen, M. L.; Minnis, P.; Smith, W. L., Jr.; Nguyen, L.

    2001-01-01

    While the various instruments maintained at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility (CF) provide detailed cloud and radiation measurements for a small area, satellite cloud property retrievals provide a means of examining the large-scale properties of the surrounding region over an extended period of time. Seasonal and inter-annual climatological trends can be analyzed with such a dataset. For this purpose, monthly datasets of cloud and radiative properties from December 1996 through November 1999 over the SGP region have been derived using the layered bispectral threshold method (LBTM). The properties derived include cloud optical depths (ODs), temperatures and albedos, and are produced on two grids of lower (0.5 deg) and higher resolution (0.3 deg) centered on the ARM SGP CF. The extensive time period and high-resolution of the inner grid of this dataset allows for comparison with the suite of instruments located at the ARM CF. In particular, Whole-Sky Imager (WSI) and the Active Remote Sensing of Clouds (ARSCL) cloud products can be compared to the cloud amounts and heights of the LBTM 0.3 deg grid box encompassing the CF site. The WSI provides cloud fraction and the ARSCL computes cloud fraction, base, and top heights using the algorithms by Clothiaux et al. (2001) with a combination of Belfort Laser Ceilometer (BLC), Millimeter Wave Cloud Radar (MMCR), and Micropulse Lidar (MPL) data. This paper summarizes the results of the LBTM analysis for 3 years of GOES-8 data over the SGP and examines the differences between surface and satellite-based estimates of cloud fraction.

  19. A 10-year climatology of vertical properties of most active convective clouds over the Indian regions using TRMM PR

    NASA Astrophysics Data System (ADS)

    Kumar, Shailendra

    2017-01-01

    Vertical distribution of hydrometeors in the most intense convective clouds over the Indian region during the summer monsoon season (JJAS) is described for ten climatologically important areas. Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) 3D radar reflectivity data is used in the present study for 10 years (2001-2010). The study constructs a convective cloud cell based on reflectivity thresholds, known as most intense convective cloud. The cloud cells are formed by taking the maximum reflectivity (Ze) at each altitude in the convective area with at least one radar pixel containing reflectivity of 40 dBZ or more. TRMM 2A23 data was used to eliminate the stratiform clouds from our analyses. The Vertical structure of convective clouds were studied over the east and west coast of India, and observation shows that the east coast consists of a higher frequency of convective clouds with high reflectivity values in average vertical profiles. It is observed that over the northeastern parts of the Indian subcontinent, 30 % of convective cells extend beyond 15-km height whereas it is only 4 % over the central Bay of Bengal. Over the Western Ghats, 13 % of the cells have their tops below the freezing level, i.e. warm clouds do give heavy rain here. The regional differences in the vertical profile are high between the 5- and 12-km altitude. Most intense convective cells (MICCs) with a cloud top height more than 10 and 15 km show different characteristics, and the Western Ghats shows the most intense average vertical profile. Above 12 km, the western coast shows increased reflectivity value. Convective intensity is higher over the land-dominated areas for the cloud cells and decreases when we restrict the cloud cells to a certain altitude.

  20. The ESA Cloud_cci project: generation of multi-decadal consistent global data sets for GCOS cloud property ECVs using an optimal estimation approch

    NASA Astrophysics Data System (ADS)

    Schlundt, Cornelia; Sus, Oliver; Stapelberg, Stefan; Stengel, Martin; Hollmann, Rainer; Poulsen, Caroline

    2015-04-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial ECV data products. The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System (GCOS). The objective target within the ESA Cloud_cci project is the investigation of synergetic capabilities of past, existing and upcoming European and American satellite missions and thus, the generation of long-term coherent cloud property datasets covering 33 years. The cloud properties considered are cloud mask, cloud top estimates, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the first phase of the project along with further developments and improvements in the retrieval scheme and hence the quality of the cloud products carried out in the second phase of the project. Moreover, we will show exemplary results of comprehensive validation with other well established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6). These inter-comparison results will show the strengths and weaknesses of the Cloud_cci datasets.

  1. Lidar Studies of Extinction in Clouds in the ECLIPS Project

    NASA Technical Reports Server (NTRS)

    Martin, C.; Platt, R.; Young, Stuart A.; Patterson, Graeme P.

    1992-01-01

    The Experimental Cloud Lidar Pilot Study (ECLIPS) project has now had two active phases in 1989 and 1991. A number of laboratories around the world have taken part in the study. The observations have yielded new data on cloud height and structure, and have yielded some useful new information on the retrieval of cloud optical properties, together with the uncertainties involved. Clouds have a major impact on the climate of the earth. They have the effect of reducing the mean surface temperature from 30 C for a cloudless planet to a value of about 15 C for present cloud conditions. However, it is not at all certain how clouds would react to a change in the planetary temperature in the event of climate change due to a radiative forcing from greenhouse gases. Clouds both reflect out sunlight (negative feedback) and enhance the greenhouse effect (positive feedback), but the ultimate sign of cloud feedback is unknown. Because of these uncertainties, campaigns to study clouds intensely were initiated. The International Satellite Cloud Climatology (ISCPP) and the FIRE Campaigns (cirrus and stratocumulus) are examples. The ECLIPS was set up similarly to the above experiments to obtain information specifically on cloud base, but also cloud top (where possible), optical properties, and cloud structure. ECLIPS was designed to allow as many laboratories as possible globally to take part to get the largest range of clouds. It involves observations with elastic backscatter lidar, supported by infrared fluxes at the ground and radiosonde data, as basic instrumentation. More complex experiments using beam filter radiometers, solar pyranometers, and satellite data and often associated with other campaigns were also encouraged to join ECLIPS. Two periods for observation were chosen, Sep. - Dec. 1989 and Apr. - Jul. 1992 into which investigators were requested to fit 30 days of observations. These would be either continuous, or arranged to coincide with NOAA satellite overpasses to

  2. The Cloud2SM Project

    NASA Astrophysics Data System (ADS)

    Crinière, Antoine; Dumoulin, Jean; Mevel, Laurent; Andrade-Barosso, Guillermo; Simonin, Matthieu

    2015-04-01

    From the past decades the monitoring of civil engineering structure became a major field of research and development process in the domains of modelling and integrated instrumentation. This increasing of interest can be attributed in part to the need of controlling the aging of such structures and on the other hand to the need to optimize maintenance costs. From this standpoint the project Cloud2SM (Cloud architecture design for Structural Monitoring with in-line Sensors and Models tasking), has been launched to develop a robust information system able to assess the long term monitoring of civil engineering structures as well as interfacing various sensors and data. The specificity of such architecture is to be based on the notion of data processing through physical or statistical models. Thus the data processing, whether material or mathematical, can be seen here as a resource of the main architecture. The project can be divided in various items: -The sensors and their measurement process: Those items provide data to the main architecture and can embed storage or computational resources. Dependent of onboard capacity and the amount of data generated it can be distinguished heavy and light sensors. - The storage resources: Based on the cloud concept this resource can store at least two types of data, raw data and processed ones. - The computational resources: This item includes embedded "pseudo real time" resources as the dedicated computer cluster or computational resources. - The models: Used for the conversion of raw data to meaningful data. Those types of resources inform the system of their needs they can be seen as independents blocks of the system. - The user interface: This item can be divided in various HMI to assess maintaining operation on the sensors or pop-up some information to the user. - The demonstrators: The structures themselves. This project follows previous research works initiated in the European project ISTIMES [1]. It includes the infrared

  3. KLIMHIST: A Project on Historical Climatology in Portugal

    NASA Astrophysics Data System (ADS)

    Fragoso, Marcelo; João Alcoforado, Maria; Santos, João A.

    2013-04-01

    Climatic variability from the beginning of regular meteorological observations is now acknowledged. However, climate change prior to 1900 is far from being well known in Portugal, except for the 1675-1800 period in Southern Portugal. An interdisciplinary team is working in the frame of the KLIMHIST PROJECT ("Reconstruction and model simulations of past climate in Portugal using documentary and early instrumental sources, 17th-19th century)", since May 2012. The main objectives of the project are: (i) to contribute to the creation of a long-term history of climate in Portugal by producing databases of documentary evidence and of instrumental data since 1645, a period of natural climate variability that includes the Maunder Minimum and the Dalton Minimum; (ii) to search systematically for the first simultaneous documentary and instrumental data in order to calibrate the series; (iii) to analyse simulated multi-decadal trends over Portugal generated by climate models; (iv) to compare results with those obtained from dendroclimatology and from geothermal studies regarding Portugal and (v) to study extreme events of the past, their impacts and the vulnerability of societies to weather during the last 350 years, and compare them with current analogues. With these tasks, we expect to help completing the spatial coverage of past European climate, as the data gap over SW Europe is often mentioned. As the team members come from four different Universities in Portugal (Évora, Lisbon, Oporto and UTAD), we expect to obtain a good spatial representation of documentary evidence. Teams are now progressing in data search activities in archives. An Access database frame was constructed. Some 18th century extreme events have been and are being studied (Barbara storm, Dec.1739, among others). The first workshop took place in Lisbon (October 2012): Prof Brázdil and Dr. Domínguez-Castro (two of our consultants) were keynote speakers. Key-words: Climate reconstruction, Documentary

  4. A satellite-based 13-year climatology of net cloud radiative forcing over the Indian monsoon region

    NASA Astrophysics Data System (ADS)

    Saud, Trailokya; Dey, Sagnik; Das, Sushant; Dutta, Soumi

    2016-12-01

    We present a satellite-based 13-year (Mar. 2000-Feb. 2013) climatology of net cloud radiative forcing (CRF) over the Indian monsoon region (0-40°N, 60-100°E) using the Clouds and Earth's Radiant Energy System (CERES) radiation data and explained the net CRF variability in terms of cloud properties retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS). Mean (± 1σ) seasonal shortwave (SW) CRF values averaged over the region are - 82.7 ± 24.5, - 32.1 ± 12.1, - 17.2 ± 5.3 and - 30.2 ± 16.2 W m- 2 respectively for the monsoon (JJAS), post-monsoon (ON), winter (DJF) and pre-monsoon (MAM) seasons; while the corresponding longwave (LW) CRF values are 53.7 ± 14.2, 27.9 ± 10.0, 15.8 ± 7.0 and 25.2 ± 9.1 W m- 2. Regional analysis reveals the largest (least) negative net CRF over the northeast (northwest) rainfall homogeneous zone throughout the year due to the dominance of optically thick high clouds (low cloud fraction, fc). Mean JJAS fc is found to increase (by > 0.01 per year) over large parts of the Arabian Sea, Bay of Bengal and the northwest region. Mean annual net CRF values for cumulus, stratocumulus and stratus (low level), altocumulus, altostratus and nimbostratus (mid-level clouds) and cirrus, cirrostratus and deep-convective (high level) clouds over the Indian monsoon region are estimated to be - 0.8, - 4.7, - 6.9, + 3.3, - 6.3, - 23.3, + 5.4, - 23.3 and - 42.1 W m- 2 respectively. Across a wide range of cloud optical depth (COD) and fc < 0.6, near cancellation of SW cooling by LW warming, is observed for low clouds. Net CRF drops below - 15 W m- 2 for clouds evolving above 400 hPa, mainly in the monsoon season. Our results demonstrate that net CRF variability in the Indian monsoon region can be explained by variability in Cloud Top Pressure (CTP), COD and fc. The study highlights the need for resolving a multi-layer cloud field in the future.

  5. Climatology of clouds and precipitation over East Antarctica using ground-based remote sensing at the Princess Elizabeth station

    NASA Astrophysics Data System (ADS)

    Souverijns, Niels; Gossart, Alexandra; Gorodetskaya, Irina; Lhermitte, Stef; Van Tricht, Kristof; Mangold, Alexander; Laffineur, Quentin; Van Lipzig, Nicole

    2016-04-01

    The surface mass balance of the Antarctic ice sheet is highly dependent on the interaction between clouds and precipitation. Our understanding of these processes is challenged by the limited availability of observations over the area and problems in Antarctic climate simulations by state-of-the-art climate models. Improvements are needed in this field, as the Antarctic ice sheet is expected to become a dominant contributor to sea level rise in the 21st century. In 2010, an observational site was established at the Princess Elisabeth (PE) Antarctic station. PE is located in the escarpment area of Dronning Maud Land, East Antarctica (72°S, 23°E). The instruments consist of several ground-based remote sensing instruments: a ceilometer (measuring cloud-base height and vertical structure), a 24-GHz Micro Rain Radar (MRR; providing vertical profiles of radar effective reflectivity and Doppler velocity), and a pyrometer (measuring effective cloud base temperature). An automatic weather station provides info on boundary-layer meteorology (temperature, wind speed and direction, humidity, pressure), as well as broadband radiative fluxes and snow height changes. This set of instruments can be used to infer the role of clouds in the Antarctic climate system, their interaction with radiation and their impact on precipitation. Cloud and precipitation characteristics are derived from 5-year-long measurement series, which is unprecedented for the Antarctic region. Here, we present an overview of the cloud and precipitation climatology. Statistics on cloud occurrence are calculated on annual / seasonal basis and a distinction between liquid / mixed phase and ice clouds is made. One can discriminate between liquid-bearing and ice-only clouds by investigating the ceilometer attenuated backscatter, since liquid phase clouds have a much higher signal. Furthermore, by using pyrometer measurements, we are able to identify the range of temperatures at which liquid / ice clouds are

  6. Cloud-to-ground lightning over Mexico and adjacent oceanic regions: a preliminary climatology using the WWLLN dataset

    NASA Astrophysics Data System (ADS)

    Kucieńska, B.; Raga, G. B.; Rodríguez, O.

    2010-11-01

    This work constitutes the first climatological study of lightning over Mexico and adjacent oceanic areas for the period 2005-2009. Spatial and temporal distributions of cloud to ground lightning are presented and the processes that contribute to the lightning variability are analysed. The data are retrieved from the World Wide Lightning Location Network (WWLLN) dataset. The current WWLL network includes 40 stations which cover much of the globe and detect very low frequency radiation ("spherics") associated with lightning. The spatial distribution of the average yearly lightning over the continental region of Mexico shows the influence of orographic forcing in producing convective clouds with high lightning activity. However, a very high number of strikes is also observed in the States of Tabasco and Campeche, which are low-lying areas. This maximum is related to the climatological maximum of precipitation for the country and it may be associated with a region of persistent low-level convergence and convection in the southern portion of the Gulf of Mexico. The maps of correlation between rainfall and lightning provide insight into the microphysical processes occurring within the clouds. The maritime clouds close to the coastline exhibit similar properties to continental clouds as they produce very high lightning activity. The seasonal cycle of lightning registered by WWLLN is consistent with the LIS/OTD dataset for the selected regions. In terms of the annual distribution of cloud-to-ground strikes, July, August and September exhibit the highest number of strikes over continental Mexico. The diurnal cycle indicates that the maximum number of strikes over the continent is observed between 6 and 9 p.m. LT. The surrounding oceanic regions were subdivided into four distinct sectors: Gulf of Mexico, Caribbean, Sub-tropical Pacific and Tropical Pacific. The Gulf of Mexico has the broadest seasonal distribution, since during winter lightning associated with mid

  7. A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing: Part V. Cloud Structural Properties

    SciTech Connect

    Sassen, Kenneth; Wang, Likun; Starr, David O.; Comstock, Jennifer M.; Quante, Markus

    2007-07-31

    In this fifth of a series of papers describing the extended-time high cloud observation program from the University of Utah Facility for Atmospheric Remote Sensing, the structural properties of cirrus clouds over Salt Lake City, Utah, are examined. Wavelet analysis is applied as a function of cloud height to a 10-y record of ruby (0.694 um) lidar backscattering data collected from visually-identified cirrus clouds to study the presence of periodic cloud structures, such as Kelvin-Helmholtz waves, cirrus mammata, and uncinus cells (all with wavelengths of ~1-10 km), as well as longer mesoscale cloud organizations. Approximately 8.4% (18.8%, 30.8%) of the data display such periodic structures after passing a 95% (75%, 50%) confidence level test. This may signify that most cloud organizations are quasi-periodic in nature. The amount of lidar cloud data showing periodic structures does not change considerably with length scale between 0.2 to 200 km, although a preference for ~20-km mesoscale cloud structures is indicated. Using time series of vertically-integrated lidar backscattering profiles, we find a steady decrease in autocorrelation coefficients starting at a few kilometers as the length (or model grid) scale increases. Examining the variability of cirrus cloud optical depth t from an earlier LIRAD (combined lidar and infrared radiometer) analysis reveals that the standard deviation σ of t is related by σ = 0.36 t.

  8. Climatological Data for Clouds Over the Globe from Surface Observations (1988) (NDP-026)

    DOE Data Explorer

    Hahn, C. J.; Warren, S. G.; London, J.; Jenne, R. L.; Chervin, R. M.

    2012-01-01

    With some data from as early as 1930, global long-term monthly and/or seasonal total cloud cover, cloud type amounts and frequencies of occurrence, low cloud base heights, harmonic analyses of annual and diurnal cycles, interannual variations and trends, and cloud type co-occurrences have been compiled and presented in two atlases (Warren et al. 1988, 1990). These data were derived from land and ship synoptic weather reports from the "SPOT" archive of the Fleet Numerical Oceanography Center (FNOC) and from Release 1 of the Comprehensive Ocean-Atmosphere Data Set (COADS) for the years 1930-1979. The data are in 12 files (one containing latitude, longitude, land-fraction, and number of land stations for grid boxes; four containing total cloud, cloud types, harmonic analyses, and interannual variations and trends for land; four containing total cloud, cloud types, harmonic analyses, and interannual variations and trends for oceans; one containing first cloud analyses for the first year of the GARP Global Experiment (FGGE); one containing cloud-type co-occurrences for land and oceans; and one containing a FORTRAN program to read and produce maps).

  9. Examinations of cloud variability and future change in the coupled model intercomparison project phase 3 simulations

    NASA Astrophysics Data System (ADS)

    Shin, Sun-Hee; Lee, Myong-In; Kim, Ok-Yeon

    2014-08-01

    Low-level cloud variability is critical to the radiation balance of Earth due to its wide spatial coverage. Using the adjusted International Satellite Cloud Climatology Project (ISCCP) observations of Clement et al. (2009), and the Coupled Model Intercomparison Project Phase 3 (CMIP3) model simulations, this study examines the observed and the simulated low-cloud variations and their relationships with large-scale environmental variables. From the observational analysis, significant correlations are found between low clouds and those of sea surface temperature (SST), lower tropospheric stability (LTS), and sea level pressure (SLP) over tropical marine areas of low cloud prevailing regions during most of the year. Increase of SST coincides with the reduction of LTS and increased vertical motion, which tends to reduce low-level clouds in subtropical oceans. Among the 14 models investigated, CGCM3 and HadGEM1 exhibit more realistic representation of the observed relationship between low-level clouds and large-scale environments. In future climate projection, these two models show a good agreement in the reduction of low-cloud throughout much of the global oceans in response to greenhouse gas forcing, suggesting a positive low-cloud feedback in a climate change context.

  10. Climatology of Martian water ice clouds from Mars Express/OMEGA: derivation of the diurnal cycle

    NASA Astrophysics Data System (ADS)

    Szantai, A.; Audouard, J.; Madeleine, J.-B.; Forget, F.; Pottier, A.; Gondet, B.; Langevin, Y.; Bibring, J.-P.

    2015-10-01

    Images derived from the slope of the water ice absorption band between 3.4 and 3.525 μm from the OMEGA spectrometer onboard Mars Express have been used to detect clouds. From a series of OMEGA images covering 4 Martian years (between 2004 and 2011), the pixels are used to construct a cloud coverage database over a regular 4D grid in longitude,latitude, solar longitude and Martian local time. It can be used to observe the evolution of clouds over specific regions, and their diurnal and annual cycle. As an example, the diurnal cloud life cycle in the tropics (-25°S to 25°N) during the Northern summer shows the presence of thick clouds in the early morning (possibly haze), which dissipate before noon (local time). In the afternoon, the cloud cover grows again, possibly due to convection generated by the increased solar heating.

  11. Quantifying the climatological cloud-free shortwave direct radiative forcing of mineral dust aerosol over the Red Sea

    NASA Astrophysics Data System (ADS)

    Stenchikov, G. L.; Brindley, H. E.; Osipov, S.; Bantges, R. J.; Smirnov, A.; Prakash, P. J.

    2014-12-01

    While there have been a number of campaigns designed to probe dust-climate interactions over much of the world, relatively little attention has been paid to the Red Sea. Because of the remoteness of the area, satellite retrievals provide a crucial tool for assessing aerosol loading over the Sea. However, agreement between aerosol properties inferred from measurements from different instruments, and even in some cases from the same measurements using different retrieval algorithms can be poor, particularly in the case of mineral dust. Ground based measurements, which can be used to evaluate retrievals, are thus highly desirable. Here we take advantage of ship-based hand-held sun-photometer (microtops) observations gathered within the framework of NASA Aerosol Maritime Network from a series of cruises, which took place across the Red Sea during 2011 and 2013. To our knowledge these data represent the first set of detailed aerosol measurements from the Sea. They thus provide a unique opportunity to assess the performance of satellite retrieval algorithms in this region. Here we used the microtops measurements to evaluate the performance of co-located satellite retrievals from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the MODerate Imaging Spectrometer (MODIS). Both algorithms show good agreement with the ship-based measurements and with each other, although it appears that the MODIS cloud detection scheme in particular is rather conservative. The stand alone Rapid Radiative Transfer Model (RRTM) driven by reanalysis meteorological fields is used to estimate the cloud-free aerosol direct radiative effect at the surface and TOA along the ship tracks. The TOA effects are compared to co-located measurements from the Geostationary Earth Radiation Budget (GERB) instrument. Having evaluated both the quality of the retrievals and the ability of the model to capture the associated radiative effect, we will present a climatology of aerosol loading over the

  12. A Climatology of Surface Cloud Radiative Effects at the ARM Tropical Western Pacific Sites

    SciTech Connect

    McFarlane, Sally A.; Long, Charles N.; Flaherty, Julia E.

    2013-04-01

    Cloud radiative effects on surface downwelling fluxes are investigated using long-term datasets from the three Atmospheric Radiation Measurement (ARM) sites in the Tropical Western Pacific (TWP) region. The Nauru and Darwin sites show significant variability in sky cover, downwelling radiative fluxes, and surface cloud radiative effect (CRE) due to El Niño and the Australian monsoon, respectively, while the Manus site shows little intra-seasonal or interannual variability. Cloud radar measurement of cloud base and top heights are used to define cloud types so that the effect of cloud type on the surface CRE can be examined. Clouds with low bases contribute 71-75% of the surface shortwave (SW) CRE and 66-74% of the surface longwave (LW) CRE at the three TWP sites, while clouds with mid-level bases contribute 8-9% of the SW CRE and 12-14% of the LW CRE, and clouds with high bases contribute 16-19% of the SW CRE and 15-21% of the LW CRE.

  13. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II; Cloud Fraction and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Xi, Baike; Minnis, Patrick

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) central facility are analyzed for determining the variability of cloud fraction and radiative forcing at several temporal scales between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layer low (0-3 km), middle (3-6 km), and high clouds (greater than 6 km) using ARM SGP ground-based paired lidar-radar measurements. Shortwave (SW), longwave (LW), and net cloud radiative forcings (CRF) are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements. The annual averages of total, and single-layer, nonoverlapped low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Total and low cloud amounts were greatest from December through March and least during July and August. The monthly variation of high cloud amount is relatively small with a broad maximum from May to August. During winter, total cloud cover varies diurnally with a small amplitude, mid-morning maximum and early evening minimum, and during summer it changes by more than 0.14 over the daily cycle with a pronounced early evening minimum. The diurnal variations of mean single-layer cloud cover change with season and cloud height. Annual averages of all-sky, total, and single-layer high, middle, and low LW CRFs are 21.4, 40.2, 16.7, 27.2, and 55.0 Wm(sup -2), respectively; and their SW CRFs are -41.5, -77.2, -37.0, -47.0, and -90.5 Wm(sup -2). Their net CRFs range from -20 to -37 Wm(sup -2). For all-sky, total, and low clouds, the maximum negative net CRFs of -40.1, -70, and -69.5 Wm(sup -2), occur during April; while the respective minimum values of -3.9, -5.7, and -4.6 Wm(sup -2), are found during December. July is the month having maximum negative net CRF of -46.2 Wm(sup -2) for middle clouds, and May has the maximum value of -45.9 Wm(sup -2) for high clouds. An

  14. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part II; Cloud Fraction and Surface Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Xi, B.; Minnis, P.

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (0-3 km), middle (3-6 km), and high clouds (more than 6 km) using ARM SCG ground-based paired lidar-radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of approximately 10 Wm(exp -2). The annual averages of total, and single-layered low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total and low cloud amounts peak during January and February and reach a minimum during July and August, high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 Wm(exp-2), respectively) are less than those under middle and high clouds (188 and 201 Wm(exp -2), respectively), but the downwelling LW fluxes (349 and 356 Wm(exp -2)) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 Wm(exp -2)). Low clouds produce the largest LW warming (55 Wm(exp -2) and SW cooling (-91 Wm(exp -2)) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 Wm(exp -2)) and SW cooling (-37 Wm(exp -2)) effects at the surface. All-sky SW CRF decreases and LW CRF increases with increasing cloud fraction with mean slopes of -0.984 and 0.616 Wm(exp -2)%(exp -1), respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly

  15. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part II; Cloud Fraction and Surface Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Xi, B.; Minnis, P.

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (0-3 km), middle (3-6 km), and high clouds (more than 6 km) using ARM SCG ground-based paired lidar-radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of approximately 10 Wm(exp -2). The annual averages of total, and single-layered low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total and low cloud amounts peak during January and February and reach a minimum during July and August, high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 Wm(exp-2), respectively) are less than those under middle and high clouds (188 and 201 Wm(exp -2), respectively), but the downwelling LW fluxes (349 and 356 Wm(exp -2)) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 Wm(exp -2)). Low clouds produce the largest LW warming (55 Wm(exp -2) and SW cooling (-91 Wm(exp -2)) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 Wm(exp -2)) and SW cooling (-37 Wm(exp -2)) effects at the surface. All-sky SW CRF decreases and LW CRF increases with increasing cloud fraction with mean slopes of -0.984 and 0.616 Wm(exp -2)%(exp -1), respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly

  16. A Climatological Study of Cloud to Ground Lightning Strikes in the Vicinity of the Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Burns, Lee; Decker, Ryan

    2004-01-01

    Lightning strike location and peak current are monitored operationally in the Kennedy Space Center (KSC)/Cape Canaveral Air Force Station (CCAFS) area by the Cloud to Ground Lightning Surveillance System (CGLSS). The present study compiles ten years of CGLSS data into a climatological database of all strikes recorded within a 20-mile radius of space shuttle launch platform LP39A, which serves as a convenient central point. The period of record (POR) for the database runs from January 1, 1993 to December 31, 2002. Histograms and cumulative probability curves are produced to determine the distribution of occurrence rates for the spectrum of strike intensities (given in kA). Further analysis of the database provides a description of both seasonal and interannual variations in the lightning distribution.

  17. A Climatology of Fair-Weather Cloud Statistics at the Atmospheric Radiation Measurement Program Southern Great Plains Site: Temporal and Spatial Variability

    SciTech Connect

    Berg, Larry K.; Kassianov, Evgueni I.; Long, Charles N.; Gustafson, William I.

    2006-03-30

    In previous work, Berg and Stull (2005) developed a new parameterization for Fair-Weather Cumuli (FWC). Preliminary testing of the new scheme used data collected during a field experiment conducted during the summer of 1996. This campaign included a few research flights conducted over three locations within the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site. A more comprehensive verification of the new scheme requires a detailed climatology of FWC. Several cloud climatologies have been completed for the ACRF SGP, but these efforts have focused on either broad categories of clouds grouped by height and season (e.g., Lazarus et al. 1999) or height and time of day (e.g., Dong et al. 2005). In these two examples, the low clouds were not separated by the type of cloud, either stratiform or cumuliform, nor were the horizontal chord length (the length of the cloud slice that passed directly overhead) or cloud aspect ratio (defined as the ratio of the cloud thickness to the cloud chord length) reported. Lane et al. (2002) presented distributions of cloud chord length, but only for one year. The work presented here addresses these shortcomings by looking explicitly at cases with FWC over five summers. Specifically, we will address the following questions: •Does the cloud fraction (CF), cloud-base height (CBH), and cloud-top height (CTH) of FWC change with the time of day or the year? •What is the distribution of FWC chord lengths? •Is there a relationship between the cloud chord length and the cloud thickness?

  18. The first ISLSCP field experiment (FIFE). [International Satellite Land Surface Climatology Project

    NASA Technical Reports Server (NTRS)

    Sellers, P. J.; Hall, F. G.; Asrar, G.; Strebel, D. E.; Murphy, R. E.

    1988-01-01

    The background and planning of the first International Satellite Land Surface Climatology Project (ISLSCP) field experiment (FIFE) are discussed. In FIFE, the NOAA series of satellites and GOES will be used to provide a moderate-temporal resolution coarse-spatial resolution data set, with SPOT and aircraft data providing the high-spatial resolution pointable-instrument capability. The paper describes the experiment design, the measurement strategy, the configuration of the site of the experiment (which will be at and around the Konza prairie near Manhattan, Kansas), and the experiment's operations and execution.

  19. The ESA Cloud_cci Project: Generation of Multi-Decadal, Consistent, Global Data Sets of Cloud Properties with Uncertainty Information

    NASA Astrophysics Data System (ADS)

    Stapelberg, S.; Stengel, M.; Schlundt, C.; Sus, O.; Hollmann, R.; Poulsen, C. A.

    2015-12-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial "essential climate variables (ECV)". The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System. The objective target within the ESA Cloud_cci project is the generation of long-term coherent cloud property datasets covering 33 years that also provide mathematically consistent uncertainty information following the optimal estimation (OE) retrieval theory. The cloud properties considered are cloud mask, cloud top level estimates, cloud thermodynamic phase, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the project so far along with ongoing further developments that currently take place. Our results will be compared with other well-established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6, SYNOP). These inter-comparison results will indicate the strengths and weaknesses of the Cloud_cci datasets. Finally, we will present long-term time series of the retrieved cloud variables for AVHRR (1982-2014) that enable global, multi-decadal analyses of clouds.

  20. The ESA Cloud_cci project: generation of multi-decadal, consistent, global data sets of cloud properties with uncertainty information

    NASA Astrophysics Data System (ADS)

    Stapelberg, Stefan; Finkensieper, Stephan; Stengel, Martin; Schlundt, Cornelia; Sus, Oliver; Hollmann, Rainer; Poulsen, Caroline; ESA Cloud cci Team

    2016-04-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial "essential climate variables (ECV)". The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System. The objective target within the ESA Cloud_cci project is the generation of long-term coherent cloud property datasets covering 33 years that also provide mathematically consistent uncertainty information following the optimal estimation (OE) retrieval theory. The cloud properties considered are cloud mask, cloud top level estimates, cloud thermodynamic phase, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the project so far along with ongoing further developments that currently take place. Our results will be compared with other well-established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6, SYNOP). These inter-comparison results will indicate the strengths and weaknesses of the Cloud_cci datasets. Finally, we will present long-term time series of the retrieved cloud variables for AVHRR (1982-2014) that enable global, multi-decadal analyses of clouds.

  1. An aerosol climatology for the Jungfraujoch, Part 1: Criteria for cloud presence and boundary layer influence

    NASA Astrophysics Data System (ADS)

    Herrmann, Erik; Weingartner, Ernest; Gysel, Martin; Bukowiecki, Nicolas; Hammer, Emanuel; Collaud Coen, Martine; Conen, Franz; Vuilleumier, Laurent; Baltensperger, Urs

    2014-05-01

    The high alpine research station at the Jungfraujoch in Switzerland is located at 3580 m asl. Depending on meteorological conditions, the station is in the planetary boundary layer or in the free troposphere; and often it is inside clouds. In one location, it is thus possible to study aerosols under very different conditions. These possibilities have been recognized early on, with aerosol measurements starting in 1995. Over the years, the instrumentation has been extended significantly, today including various measurements of aerosol optical properties (nephelometer, aethalometer, MAAP) as well as aerosol size distribution (SMPS, OPC, APS). Additionally, the station regularly hosts campaigns (e.g. CLACE) with a multitude of additional devices, mostly focusing on new particle formation, cloud condensation nuclei, and ice nuclei. However, there are no continuously operated direct measurements to determine whether the station is in the clouds or not, whether it is in the PBL or the free troposphere. As these are essential parameters to describe the aerosol observed at the station, we present approaches to describe them based on the observations available to us. The intuitive choices to look at in terms of clouds are relative humidity and dew point. When comparing dew point and ambient temperature, a clear criterion to identify clouds can be easily deducted. However, the determination of "no clouds" is more ambiguous. Based on longwave radiation measurements performed routinely at the site, it is possible to calculate the sky temperature, i.e. the temperature at the point of origin of the radiation. When within a cloud, the sky temperature should be identical or at least close to ambient temperature. The comparison of sky and ambient temperature shows two clear clusters which can be interpreted as "cloud" and "no cloud". One has to note that in case of inversion or clouds shortly above the research station, this approach will produce false positives. However, combining

  2. Satellite Sounder-Based OLR-, Cloud- and Atmospheric Temperature Climatologies for Climate Analyses

    NASA Technical Reports Server (NTRS)

    Molnar, Gyula I.; Susskind, Joel

    2006-01-01

    Global energy balance of the Earth-atmosphere system may change due to natural and man-made climate variations. For example, changes in the outgoing longwave radiation (OLR) can be regarded as a crucial indicator of climate variations. Clouds play an important role -still insufficiently assessed in the global energy balance on all spatial and temporal scales, and satellites provide an ideal platform to measure cloud and large-scale atmospheric variables simultaneously. The TOVS series of satellites were the first to provide this type of information since 1979. OLR [Mehta and Susskind], cloud cover and cloud top pressure [Susskind et al] are among the key climatic parameters computed by the TOVS Pathfinder Path-A algorithm using mainly the retrieved temperature and moisture profiles. AIRS, regarded as the new and improved TOVS , has a much higher spectral resolution and greater S/N ratio, retrieving climatic parameters with higher accuracy. First we present encouraging agreements between MODIS and AIRS cloud top pressure (C(sub tp) and effective (A(sub eff), a product of infrared emissivity at 11 microns and physical cloud cover or A(sub c)) cloud fraction seasonal and interannual variabilities for selected months. Next we present validation efforts and preliminary trend analyses of TOVS-retrieved C(sub tp) and A(sub eff). For example, decadal global trends of the TOVS Path-A and ISCCP-D2 P(sub c), and A(sub eff)/A(sub c), values are similar. Furthermore, the TOVS Path-A and ISCCP-AVHRR [available since 19831 cloud fractions correlate even more strongly, including regional trends. We also present TOVS and AIRS OLR validation effort results and (for the longer-term TOVS Pathfinder Path-A dataset) trend analyses. OLR interannual spatial variabilities from the available state-of-the-art CERES measurements and both from the AIRS [Susskind et al] and TOVS OLR computations are in remarkably good agreement. Global monthly mean CERES and TOVS OLR time series show very good

  3. NEWS Climatology Project: The State of the Water Cycle at Continental to Global Scales

    NASA Technical Reports Server (NTRS)

    Rodell, Matthew; LEcuyer, Tristan; Beaudoing, Hiroko Kato; Olson, Bill

    2011-01-01

    NASA's Energy and Water Cycle Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy cycle consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the NEWS Water and Energy Cycle Climatology project is to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. The project is a multiinstitutional collaboration with more than 20 active contributors. This presentation will describe results of the first stage of the water budget analysis, whose goal was to characterize the current state of the water cycle on mean monthly, continental scales. We examine our success in closing the water budget within the expected uncertainty range and the effects of forcing budget closure as a method for refining individual flux estimates.

  4. The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present)

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.; Huffman, George J.; Chang, Alfred; Ferraro, Ralph; Xie, Ping-Ping; Janowiak, John; Rudolf, Bruno; Schneider, Udo; Curtis, Scott; Bolvin, David

    2003-01-01

    The Global Precipitation Climatology Project (GPCP) Version 2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 degrees x 2.5 degrees latitude-longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The data set is extended back into the premicrowave era (before 1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the raingauge analysis. This monthly analysis is the foundation for the GPCP suite of products including those at finer temporal resolution, satellite estimate, and error estimates for each field. The 23-year GPCP climatology is characterized, along with time and space variations of precipitation.

  5. Argonne's Magellan Cloud Computing Research Project

    ScienceCinema

    Beckman, Pete

    2016-07-12

    Pete Beckman, head of Argonne's Leadership Computing Facility (ALCF), discusses the Department of Energy's new $32-million Magellan project, which designed to test how cloud computing can be used for scientific research. More information: http://www.anl.gov/Media_Center/News/2009/news091014a.html

  6. Argonne's Magellan Cloud Computing Research Project

    SciTech Connect

    Beckman, Pete

    2009-01-01

    Pete Beckman, head of Argonne's Leadership Computing Facility (ALCF), discusses the Department of Energy's new $32-million Magellan project, which designed to test how cloud computing can be used for scientific research. More information: http://www.anl.gov/Media_Center/News/2009/news091014a.html

  7. Polar stratospheric cloud climatology based on Stratospheric Aerosol Measurement II observations from 1978 to 1989

    NASA Technical Reports Server (NTRS)

    Poole, Lamont R.; Pitts, Michael C.

    1994-01-01

    The probability of polar stratospheric cloud (PSC) occurrence in the Antarctic and Arctic has been estimated using Stratospheric Aerosol Measurement (SAM) II aerosol extinction data from 1978 to 1989. Antarctic PSCs are typically observed by SAM II from mid-May to early November, with a maximum zonal average probability of about 0.6 at 18-20 km in August. The typical Arctic PSC season extends only from late November to early March, with a peak zonal average probability of about 0.1 in early February at 20-22 km. There is considerable year-to-year variability in Arctic PSC sightings because of changes in the dynamics of the northern polar vortex. Year-to-year variability in Antarctic sightings is most prominent in the number of late season clouds. Maximum PSC sighting probabilities in both polar regions occur in the region from 90 deg W through the Greenwich meridian to 90 deg E, where temperatures are coldest on average. Arctic sighting probabilities approach zero outside this region, but clouds have been sighted in the Antarctic at all longitudes during most months. Inferred PSC formation temperatures remain constant throughout the Arctic winter and are similar to those in early Antarctic winter. PSC formation temperatures in the Antarctic drop markedly in the 15 to 20-km region by September, a pattern consistent with the irreversible loss of HNO3 and H2O vapor in sedimenting PSC particles.

  8. Cloud cover climatologies in the Mediterranean obtained from satellites, surface observations, reanalyses, and CMIP5 simulations: validation and future scenarios

    NASA Astrophysics Data System (ADS)

    Enriquez-Alonso, Aaron; Sanchez-Lorenzo, Arturo; Calbó, Josep; González, Josep-Abel; Norris, Joel R.

    2016-07-01

    Clouds are an important regulator of climate due to their connection to the water balance of the atmosphere and their interaction with solar and infrared radiation. In this study, monthly total cloud cover (TCC) records from different sources have been inter-compared on annual and seasonal basis for the Mediterranean region and the period 1984-2005. Specifically, gridded databases from satellite projects (ISCCP, CLARA, PATMOS-x), from reanalysis products (ERA-Interim, MERRA), and from surface observations over land (EECRA) and ocean (ICOADS) have been examined. Then, simulations from 44 climate runs of the Coupled Model Intercomparison Project phase 5 corresponding to the historical scenario have been compared against the observations. Overall, we find good agreement between the mean values of TCC estimated from the three satellite products and from surface observations, while reanalysis products show much lower values across the region. Nevertheless, all datasets show similar behavior regarding the annual cycle of TCC. In addition, our results indicate an underestimation of TCC from climate model simulations as compared to the satellite products, especially during summertime, although the annual cycle is well simulated by most models. This result is quite general and apparently independent of the cloud parameterizations included in each particular model. Equally, similar results are obtained if the ISCCP simulator included in the Cloud Feedback Model Intercomparison Project Observation Simulator Package is considered, despite only few models provide the post-processed results. Finally, GCM projections of TCC over the Mediterranean are presented. These projections predict a reduction of TCC during the 21st century in the Mediterranean. Specifically, for an extreme emission scenario (RCP8.5) the projected relative rate of TCC decrease is larger than 10 % by the end of the century.

  9. Midlatitude cirrus cloud climatology from the Facility for Atmospheric Remote Sensing. IV. Optical displays.

    PubMed

    Sassen, Kenneth; Zhu, Jiang; Benson, Sally

    2003-01-20

    In this fourth of a series of papers that describe long-term cloud research at the Facility for Atmospheric Remote Sensing at Salt Lake City, Utah, an approximately 10-year record of polarization lidar and photographic observations is analyzed to characterize the occurrence of optical displays in our local varieties of midlatitude cirrus clouds. The frequencies of occurrence of various types of halo, arc, and corona displays are evaluated according to their appearance and longevity over nominal 1-h observation periods and to the meteorological source of the cirrus. We find that complex halo-arc displays are rare at our locale and that even the so-called common 22 degree halo occurs infrequently as a complete long-lived ring. For example, only approximately 6% of the 1561-h daytime cirrus periods have bright and prolonged 22 degree halos, although a total of 37.3% have some indications of this halo, even if they are brief and fragmentary. Other fairly frequent features are the 22 degree upper tangent arc (8.6%), 22 degree parhelia (8.5%), and solar corona (7.2%). Of the optical displays observed, 83.6% are refraction based, only 1.9% are due to reflection phenomena, and a surprising 15.4% are caused by diffraction. Complex halo-arc displays are disproportionally associated with cirrus formed in tropical or subtropical airflow and also contain more horizontally oriented planar ice crystals. Lidar linear depolarization ratios from a subset of vivid displays show significant differences between halo- and the corona-producing cirrus, reflecting the effects of particle shape. Halos are associated with relatively warm cirrus that contain randomly and horizontally oriented planar ice crystals, whereas the colder corona cirrus produce much stronger depolarization from crystals too small to be uniformly oriented. Comparisons are made with available information from other locales, and we attempt to explain the geographical differences in terms of basic cirrus cloud processes.

  10. The New 20-Year Global Precipitation Climatology Project (GPCP) Merged Satellite and Rainguage Monthly Analysis

    NASA Technical Reports Server (NTRS)

    Adler, Robert; Huffman, George; Xie, Ping Ping; Rudolf, Bruno; Gruber, Arnold; Janowiak, John

    1999-01-01

    A new 20-year, monthly, globally complete precipitation analysis has been completed as part of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP). This Version 2 of the community generated data set is a result of combining the procedures and data sets as described. The global, monthly, 2.5x 2.5 degree latitude-longitude product utilizes precipitation estimates from low-orbit microwave sensors (SSM/1) and geosynchronous IR sensors and raingauge information over land. The low-orbit microwave estimates are used to adjust or correct the geosynchronous IR estimates, thereby maximizing the utility of the more physically-based microwave estimates and the finer time sampling of the geosynchronous observations. Information from raingauges is blended into the analyses over land. In the 1986-present period TOVS-based precipitation estimates are adjusted to GPCP fields and used in polar regions to produce globally-complete results. The extension back to 1979 utilizes the procedures of Xie and Arkin and their OLR Precipitation Index (OPI). The 20-year climatology of the Version 2 GPCP analysis indicates the expected features of a very strong Pacific Ocean ITCZ and SPCZ with maximum 20-year means approaching 10 mm/day. A similar strength maximum over land is evident over Borneo. Weaker maxima in the tropics occur in the Atlantic ITCZ and over South America and Africa. In mid-latitudes of the Northern Hemisphere the Western Pacific and Western Atlantic maxima have values of approximately 7 mm/day, while in the Southern Hemisphere the mid-latitude maxima are located southeast of Africa, in mid-Pacific as an extension of the SPCZ and southeast of South America. In terms of global totals the GPCP analysis shows 2.7 mm/day (3.0 mm/day over ocean; 2.1 mm/day over land), similar to the Jaeger climatology, but not other climatologies. Zonal averages peak at 6 mm/day at 7*N with mid-latitude peaks of about 3 mm/day at 40-45* latitude

  11. The New 20-Year Global Precipitation Climatology Project (GPCP) Merged Satellite and Rainguage Monthly Analysis

    NASA Technical Reports Server (NTRS)

    Adler, Robert; Huffman, George; Xie, Ping Ping; Rudolf, Bruno; Gruber, Arnold; Janowiak, John

    1999-01-01

    A new 20-year, monthly, globally complete precipitation analysis has been completed as part of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP). This Version 2 of the community generated data set is a result of combining the procedures and data sets as described. The global, monthly, 2.5x 2.5 degree latitude-longitude product utilizes precipitation estimates from low-orbit microwave sensors (SSM/1) and geosynchronous IR sensors and raingauge information over land. The low-orbit microwave estimates are used to adjust or correct the geosynchronous IR estimates, thereby maximizing the utility of the more physically-based microwave estimates and the finer time sampling of the geosynchronous observations. Information from raingauges is blended into the analyses over land. In the 1986-present period TOVS-based precipitation estimates are adjusted to GPCP fields and used in polar regions to produce globally-complete results. The extension back to 1979 utilizes the procedures of Xie and Arkin and their OLR Precipitation Index (OPI). The 20-year climatology of the Version 2 GPCP analysis indicates the expected features of a very strong Pacific Ocean ITCZ and SPCZ with maximum 20-year means approaching 10 mm/day. A similar strength maximum over land is evident over Borneo. Weaker maxima in the tropics occur in the Atlantic ITCZ and over South America and Africa. In mid-latitudes of the Northern Hemisphere the Western Pacific and Western Atlantic maxima have values of approximately 7 mm/day, while in the Southern Hemisphere the mid-latitude maxima are located southeast of Africa, in mid-Pacific as an extension of the SPCZ and southeast of South America. In terms of global totals the GPCP analysis shows 2.7 mm/day (3.0 mm/day over ocean; 2.1 mm/day over land), similar to the Jaeger climatology, but not other climatologies. Zonal averages peak at 6 mm/day at 7*N with mid-latitude peaks of about 3 mm/day at 40-45* latitude

  12. Building a Global Network of Hydro-climatology Sites in Cloud-affected Tropical Montane Forests

    NASA Astrophysics Data System (ADS)

    Moore, G. W.; Asbjornsen, H.; Bruijnzeel, S., Sr.; Berry, Z. C.; Giambelluca, T. W.; Martin, P.; Mulligan, M.

    2015-12-01

    Tropical montane forests are characteristically wet environments with low evapotranspiration and sometimes significant contributions from fog interception. They are often located at headwater catchments critical for water supplies, but ecohydroclimate data in these regions are sparse. Such evidence may be crucial for assessing climate alterations in these sensitive ecosystems. As part of a global effort led by the Tropical Montane Cloud Forest Research Coordination Network (Cloudnet - http://cloudnet.agsci.colostate.edu), we aim to extend the network of tropical montane forest sites and establish robust protocols for measuring key ecohydroclimatic parameters, including fog interception, windblown rain, throughfall, leaf wetness, and micrometeorological conditions. Specific recommendations for standardized protocols include (1) rain and fog collectors uniquely designed to separately quantify fog interception from direct rain inputs, even in windy conditions, (2) trough-style throughfall gages that collect 40 times the area of a typical tipping bucket gage with added features to reduce splash-out, (3) clusters of leaf wetness sensors to differentiate frequency and duration of wetness caused by rain and fog on windward and leeward exposures, and (4) basic micrometeorological sensors for solar radiation, temperature, humidity, and wind. At sites where resources allow for additional measurements, we developed protocols for quantifying soil moisture, soil saturation, and plant water uptake from both roots and leaves (i.e. foliar absorption), since these are also important drivers in these systems. Participating sites will be invited to contribute to a global meta-analysis that will provide new insights into the ecohydrology of cloud-affected tropical montane forests.

  13. Using Cloud-to-Ground Lightning Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida

    NASA Technical Reports Server (NTRS)

    Lambert, Winnie; Sharp, David; Spratt, Scott; Volkmer, Matthew

    2005-01-01

    Each morning, the forecasters at the National Weather Service in Melbourn, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (http://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in central Florida, especially during the warm season months of May-September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC (0700 AM EST) each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Currently, the forecasters create each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale flow regime. The intent is to increase consistency between forecasters while enabling them to focus on

  14. A cloud-to-ground lightning climatology for north-eastern Italy

    NASA Astrophysics Data System (ADS)

    Feudale, L.; Manzato, A.; Micheletti, S.

    2013-06-01

    This study analyzes the spatial distribution and temporal characteristics of cloud-to-ground lightnings (C2G) in the North East of Italy and the neighboring areas of Austria, Slovenia and Croatia. The dataset consists of about 6.5 millions C2G flash records, both positive and negative, observed between January 1995 and December 2011 by the "Centro Elettrotecnico Sperimentale Italiano-Sistema Italiano Rilevamento Fulmini'' (CESI/SIRF), part of the European Cooperation for Lightning Detection (EUCLID) Network. The results show that C2G lightnings concentrate in the foothill regions on the southern flank of the Eastern Alps with a maximum of discharge frequency of 10 lightnings per km2 per year. The number of C2G strokes varies with the period of the year: the most active period for lightning starts in April and lasts through November with the highest number of C2G strokes happening during the summer months of July and August, with maximum spatial density slightly moving from the mountain to the coastal area. The least frequency of C2G strokes is observed during wintertime. The mean diurnal C2G lightning activity for the whole domain shows a peak around 16:00-17:00 UTC and reaches a minimum around 07:00-09:00 UTC; the mean spatial distribution follows different patterns depending on the period of the day.

  15. Analysis of the Interaction and Transport of Aerosols with Cloud or Fog in East Asia from AERONET and Satellite Remote Sensing: 2012 DRAGON Campaigns and Climatological Data

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Lynch, P.; Schafer, J.; Giles, D. M.; Kim, J.; Kim, Y. J.; Sano, I.; Arola, A. T.; Munchak, L. A.; O'Neill, N. T.; Lyapustin, A.; Sayer, A. M.; Hsu, N. Y. C.; Randles, C. A.; da Silva, A. M., Jr.; Govindaraju, R.; Hyer, E. J.; Pickering, K. E.; Crawford, J. H.; Sinyuk, A.; Smirnov, A.

    2015-12-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. Major Distributed Regional Aerosol Gridded Observation Networks (DRAGON) field campaigns involving multiple AERONET sites in Japan and South Korea during Spring of 2012 have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth (AODf) signal from AERONET data for these cases of persistent and extensive cloud cover. Satellite retrievals of AOD from MODIS sensors (from Dark Target, Deep Blue and MAIAC algorithms) were also investigated to assess the issue of detectability of high AOD events associated with high cloud fraction. Underestimation of fine mode AOD by the Navy Aerosol Analysis and Prediction System (NAAPS) and by the NASA Modern-Era Retrospective Analysis For Research And Applications Aerosol Re-analysis (MERRAaero) models at very high AOD at sites in China and Korea was observed, especially for observations that are cloud screened by AERONET (Level 2 data). Additionally, multi-year monitoring at several AERONET sites are examined for climatological statistics of cloud screening of fine mode aerosol events. Aerosol that has been affected by clouds or the near-cloud environment may be more prevalent than AERONET data suggest due to inherent difficulty in

  16. Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models

    NASA Astrophysics Data System (ADS)

    Shin, Sun-Hee; Kim, Ok-Yeon; Kim, Dongmin; Lee, Myong-In

    2017-07-01

    Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850-2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006-2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about -0.99% K-1 and net radiative warming of 0.46 W m-2 K-1, suggesting a role of positive feedback to global warming.

  17. A Gridded Climatology of Clouds over Land (1971-1996) and Ocean (1954-2008) from Surface Observations Worldwide (NDP-026E)*

    DOE Data Explorer

    Hahn, C. J. [University of Arizona; Warren, S. G. [University of Washington

    2007-01-01

    Surface synoptic weather reports from ships and land stations worldwide were processed to produce a global cloud climatology which includes: total cloud cover, the amount and frequency of occurrence of nine cloud types within three levels of the troposphere, the frequency of occurrence of clear sky and of precipitation, the base heights of low clouds, and the non-overlapped amounts of middle and high clouds. Synoptic weather reports are made every three hours; the cloud information in a report is obtained visually by human observers. The reports used here cover the period 1971-96 for land and 1954-2008 for ocean. This digital archive provides multi-year monthly, seasonal, and annual averages in 5x5-degree grid boxes (or 10x10-degree boxes for some quantities over the ocean). Daytime and nighttime averages, as well as the diurnal average (average of day and night), are given. Nighttime averages were computed using only those reports that met an "illuminance criterion" (i.e., made under adequate moonlight or twilight), thus minimizing the "night-detection bias" and making possible the determination of diurnal cycles and nighttime trends for cloud types. The phase and amplitude of the first harmonic of both the diurnal cycle and the annual cycle are given for the various cloud types. Cloud averages for individual years are also given for the ocean for each of 4 seasons, and for each of the 12 months (daytime-only averages for the months). [Individual years for land are not gridded, but are given for individual stations in a companion data set, CDIAC's NDP-026D).] This analysis used 185 million reports from 5388 weather stations on continents and islands, and 50 million reports from ships; these reports passed a series of quality-control checks. This analysis updates (and in most ways supercedes) the previous cloud climatology constructed by the authors in the 1980s. Many of the long-term averages described here are mapped on the University of Washington, Department of

  18. Day and night cloud occurrence climatology for space-to-ground optical communication feasibility: the advantages of a thermal infrared sky imager

    NASA Astrophysics Data System (ADS)

    Liandrat, O.; Bertin, C.; Cros, S.; Saint-Antonin, L.

    2016-12-01

    Day and night cloud cover imaging of the sky vault from the surface has several applications such as cloud properties climatological studies or cloud cover monitoring for air traffic… Real-time hemispheric observations of cloud cover also helps to manage optical communications between a satellite and an optical ground station (OGS). Indeed, it permits to predict an eventual cloud obstruction to continue instantaneously the transmission by using an alternative OGS located in a cloud-free area of the satellite communication zone. Sky imager with a thermal infrared (TIR) camera is a convenient solution to observe continuously cloud cover evolution. The spectral broadband comprised between 7.5 and 13.5 µm permits to detect cloud, night and day, without any significant disturbance due to sunshine. This sky radiation signature has also the potential to retrieve some cloud physical properties (ceil altitude, cloud optical depth…) In this work, we propose a method to retrieve the cloud presence on a given pixel of the sky vault TIR image acquired by the SIONS-T developed by Reuniwatt and experimented by IRT Saint-Exupery. First, we estimate the clear sky radiance by selecting the pixel presenting the minimal radiance for a given set of airmass intervals. Then, this clear sky radiance is subtracted from the observed radiance in order to obtain a residual radiance, assuming this latter is only driven by cloud thermal emission. Finally, a pixel is classified as cloud if the residual radiance is 5% higher than the clear sky radiance. The method has been performed on a 1-year time-series of TIR images acquired at Côte d'Azur Observatory (France) in 2015-2016. Day time cloud images with about 2000 manually indexed pixels observed with a co-located visible sky imager have been used as truth data. Our cloud detection classify pixel correctly in more than 98 % of the cases. Variations of this accuracy according to viewing angle and cloud cover conditions are discussed.

  19. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP)

    SciTech Connect

    Key, Robert; Kozyr, Alexander; Sabine, Chris; Lee, K.; Wanninkhof, R.; Bullister, J.L.; Feely, R. A.; Millero, F. J.; Mordy, C.; Peng, T.-H.

    2004-01-01

    During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment (WOCE), the Joint Global Ocean Flux Study (JGOFS), and the Ocean Atmosphere Carbon Exchange Study (OACES). Subsequently, a group of U.S. scientists synthesized the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Results were merged into a common format data set, segregated by ocean. For comparison purposes, each ocean data set includes a small number of high-quality historical cruises. The data were subjected to rigorous quality control procedures to eliminate systematic data measurement biases. The calibrated 1990s data were used to estimate anthropogenic CO{sub 2}, potential alkalinity, CFC watermass ages, CFC partial pressure, bomb-produced radiocarbon, and natural radiocarbon. These quantities were merged into the measured data files. The data were used to produce objectively gridded property maps at a 1{sup o} resolution on 33 depth surfaces chosen to match existing climatologies for temperature, salinity, oxygen, and nutrients. The mapped fields are interpreted as an annual mean distribution in spite of the inaccuracy in that assumption. Both the calibrated data and the gridded products are available from the Carbon Dioxide Information Analysis Center. Here we describe the important details of the data treatment and the mapping procedure, and present summary quantities and integrals for the various parameters.

  20. The First International Satellite Land-Surface Climatology Project (ISLSCP) Field Experiment (FIFE)

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Sellers, P. J.

    1985-01-01

    The International Satellite Land Surface Climatology Project (ISLSCP) will verify the use of satellite data for the estimation of land-surface properties through field experiments using point measurements on the ground and areal measurements from aircraft overflights. In addition to validating satellite estimates of surface properties, it studies approaches for obtaining areal averages of the radiation, moisture and heat fluxes made using remotely sensed data. The procedure suggested combines the surface point measurements of the fluxes with the aircraft areal observations using a surface energy balance model to interpolate between the point estimates of these fluxes and calculate area-averaged quantities. The surface parameters to be estimated from aircraft observations include: surface radiation temperature, albedo, land cover or vegetation index, and surface soil moisture (the latter to be obtained using passive and active microwave approaches). The area-averages of the surface properties are compared with satellite data where possible. The First ISLSCP Field Experiment is planned for l987 at a site having relatively uniform vegetation cover in the central great plains of the USA. for 1987 at a site having relatively uniform vegetation cover in the central great plains of the USA.

  1. The Ground Reference for the Validation of the Global Precipitation Climatology Project Monthly Rainfall Estimates

    NASA Astrophysics Data System (ADS)

    Woldemariam, M. G.; Krajewski, W. F.

    2002-05-01

    The Global Precipitation Climatology Project (GPCP) provides 2.5 degree * 2.5 degree gridded datasets of monthly rainfall accumulation comprising in-situ observation from rain gauge and satellite derived rainfall estimates. The authors examined the issues involved in quantifying the error variance of the GPCP products. The datasets for this study came from one site over Thailand, which is equipped with an exceptional dense network of rain gauges. The authors applied the Error Variance Separation Method (EVSM), which allows assessment of the error variance separately for the gauges and GPCP estimates. An important assumption of this approach is a statistical independence between GPCP errors and gauge sampling errors. The authors showed the magnitude of the errors introduced in the GPCP estimates due to such an assumption. The authors studied the errors introduced in quantifying the GPCP error variance due to the EVSM method, for various gauge sampling density and spatial configuration of gauges, using Monte Carlo techniques. Generally speaking, 20 gauges uniformly spaced over the GPCP box area are a minimum to obtain the uncertainty of the GPCP products with an error of on the order of less than 10 percent.

  2. Improving Climate Projections by Understanding How Cloud Phase affects Radiation

    NASA Technical Reports Server (NTRS)

    Cesana, Gregory; Storelvmo, Trude

    2017-01-01

    Whether a cloud is predominantly water or ice strongly influences interactions between clouds and radiation coming down from the Sun or up from the Earth. Being able to simulate cloud phase transitions accurately in climate models based on observational data sets is critical in order to improve confidence in climate projections, because this uncertainty contributes greatly to the overall uncertainty associated with cloud-climate feedbacks. Ultimately, it translates into uncertainties in Earth's sensitivity to higher CO2 levels. While a lot of effort has recently been made toward constraining cloud phase in climate models, more remains to be done to document the radiative properties of clouds according to their phase. Here we discuss the added value of a new satellite data set that advances the field by providing estimates of the cloud radiative effect as a function of cloud phase and the implications for climate projections.

  3. Improving climate projections by understanding how cloud phase affects radiation

    NASA Astrophysics Data System (ADS)

    Cesana, Gregory; Storelvmo, Trude

    2017-04-01

    Whether a cloud is predominantly water or ice strongly influences interactions between clouds and radiation coming down from the Sun or up from the Earth. Being able to simulate cloud phase transitions accurately in climate models based on observational data sets is critical in order to improve confidence in climate projections, because this uncertainty contributes greatly to the overall uncertainty associated with cloud-climate feedbacks. Ultimately, it translates into uncertainties in Earth's sensitivity to higher CO2 levels. While a lot of effort has recently been made toward constraining cloud phase in climate models, more remains to be done to document the radiative properties of clouds according to their phase. Here we discuss the added value of a new satellite data set that advances the field by providing estimates of the cloud radiative effect as a function of cloud phase and the implications for climate projections.

  4. Status and Plans for the WCRP/GEWEX Global Precipitation Climatology Project (GPCP)

    NASA Technical Reports Server (NTRS)

    Adkerm Robert F.

    2006-01-01

    Status and plans for GPCP are presented along with scientific findings from the current data set. Global and large regional rainfall variations and possible long-term changes are examined using the 26-year (1979-2004) monthly dataset from the Global Precipitation Climatology Project (GPCP). One emphasis is to discriminate among the variations due to ENSO, volcanic events and possible long-term changes. Although the global change of precipitation in the data set is near zero, the data set does indicate an upward trend (0.13 mm/day/25yr) and a downward trend (-0.06 mm/day/25yr) over tropical oceans and lands (25S-25N), respectively. This corresponds to a 4% increase (ocean) and 2% decrease (land) during this time period. Simple techniques are derived to attempt to eliminate variations due to ENSO and major volcanic eruptions in the Tropics. Using only annual values two "volcano years" are determined by examining ocean-land coupled variations in precipitation related to ENSO and other phenomena. The outlier years coincide with Pinatubo and El Chicon eruptions. The ENSO signal is reduced by deriving mean ocean and land values for El Nino, La Nina and neutral conditions based on Nino 3.4 SST and normalizing the annual ocean and land precipitation to the neutral set of cases. The impact of the two major volcanic eruptions over the past 25 years is estimated to be about a 5% reduction in tropical rainfall. The modified data set (with ENSO and volcano effect at least partially removed) retains the same approximate linear change slopes over the data set period, but with reduced variance leading to significance tests with results in the 90-95% range. Intercomparisons between the GPCP, SSM/I (1988-2004), and TRMM (1998-2004) satellite rainfall products and alternate gauge analyses over land are made to attempt to increase or decrease confidence in the changes seen in the GPCP analysis.

  5. An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

    NASA Astrophysics Data System (ADS)

    Brindley, H.; Osipov, S.; Bantges, R.; Smirnov, A.; Banks, J.; Levy, R.; Jish Prakash, P.; Stenchikov, G.

    2015-10-01

    Ground-based and satellite observations are used in conjunction with the Rapid Radiative Transfer Model (RRTM) to assess climatological aerosol loading and the associated cloud-free aerosol direct radiative effect (DRE) over the Red Sea. Aerosol optical depth (AOD) retrievals from the Moderate Resolution Imaging Spectroradiometer and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are first evaluated via comparison with ship-based observations. Correlations are typically better than 0.9 with very small root-mean-square and bias differences. Calculations of the DRE along the ship cruises using RRTM also show good agreement with colocated estimates from the Geostationary Earth Radiation Budget instrument if the aerosol asymmetry parameter is adjusted to account for the presence of large particles. A monthly climatology of AOD over the Red Sea is then created from 5 years of SEVIRI retrievals. This shows enhanced aerosol loading and a distinct north to south gradient across the basin in the summer relative to the winter months. The climatology is used with RRTM to estimate the DRE at the top and bottom of the atmosphere and the atmospheric absorption due to dust aerosol. These climatological estimates indicate that although longwave effects can reach tens of W m-2, shortwave cooling typically dominates the net radiative effect over the Sea, being particularly pronounced in the summer, reaching 120 W m-2 at the surface. The spatial gradient in summertime AOD is reflected in the radiative effect at the surface and in associated differential heating by aerosol within the atmosphere above the Sea. This asymmetric effect is expected to exert a significant influence on the regional atmospheric and oceanic circulation.

  6. Revisiting a Hydrological Analysis Framework with International Satellite Land Surface Climatology Project Initiative 2 Rainfall, Net Radiation, and Runoff Fields

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Fekete, Balazs M.; Huffman, George J.; Stackhouse, Paul W.

    2006-01-01

    The International Satellite Land Surface Climatology Project Initiative 2 (ISLSCP-2) data set provides the data needed to characterize the surface water budget across much of the globe in terms of energy availability (net radiation) and water availability (precipitation) controls. The data, on average, are shown to be consistent with Budyko s decades-old framework, thereby demonstrating the continuing relevance of Budyko s semiempirical relationships. This consistency, however, appears only when a small subset of the data with hydrologically suspicious behavior is removed from the analysis. In general, the precipitation, net radiation, and runoff data also appear consistent in their interannual variability and in the phasing of their seasonal cycles.

  7. Potential value of satellite cloud pictures in weather modification projects

    NASA Technical Reports Server (NTRS)

    Biswas, K. R.

    1972-01-01

    Satellite imagery for one project season of cloud seeding programs in the northern Great Plains has been surveyed for its probable usefulness in weather modification programs. The research projects and the meteorological information available are described. A few illustrative examples of satellite imagery analysis are cited and discussed, along with local observations of weather and the seeding decisions made in the research program. This analysis indicates a definite correlation between satellite-observed cloud patterns and the types of cloud seeding activity undertaken, and suggests a high probability of better and/or earlier decisions if the imagery is available in real time. Infrared imagery provides better estimates of cloud height which can be useful in assessing the possibility of a hail threat. The satellite imagery appears to be of more value to area-seeding projects than to single-cloud seeding experiments where the imagery is of little value except as an aid in local forecasting and analysis.

  8. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility: Part I: Low-Level Cloud Macrophysical, Microphysical, and Radiative Properties.

    NASA Astrophysics Data System (ADS)

    Dong, Xiquan; Minnis, Patrick; Xi, Baike

    2005-05-01

    A record of single-layer and overcast low cloud (stratus) properties has been generated using approximately 4000 h of data collected from January 1997 to December 2002 at the Atmospheric Radiation Measurement (ARM) Southern Great Plains Central Facility (SCF). The cloud properties include liquid-phase and liquid-dominant mixed-phase low cloud macrophysical, microphysical, and radiative properties including cloud-base and -top heights and temperatures, and cloud physical thickness derived from a ground-based radar and lidar pair, and rawinsonde sounding; cloud liquid water path (LWP) and content (LWC), and cloud-droplet effective radius (re) and number concentration (N) derived from the macrophysical properties and radiometer data; and cloud optical depth (τ), effective solar transmission (γ), and cloud/top-of-atmosphere albedos (Rcldy/RTOA) derived from Eppley precision spectral pyranometer measurements. The cloud properties were analyzed in terms of their seasonal, monthly, and hourly variations. In general, more stratus clouds occur during winter and spring than in summer. Cloud-layer altitudes and physical thicknesses were higher and greater in summer than in winter with averaged physical thicknesses of 0.85 and 0.73 km for day and night, respectively. The seasonal variations of LWP, LWC, N, τ, Rcldy, and RTOA basically follow the same pattern with maxima and minima during winter and summer, respectively. There is no significant variation in mean re, however, despite a summertime peak in aerosol loading. Although a considerable degree of variability exists, the 6-yr average values of LWP, LWC, re, N, τ, γ, Rcldy, and RTOA are 151 gm-2 (138), 0.245 gm-3 (0.268), 8.7 μm (8.5), 213 cm-3 (238), 26.8 (24.8), 0.331, 0.672, and 0.563 for daytime (nighttime). A new conceptual model of midlatitude continental low clouds at the ARM SGP site has been developed from this study. The low stratus cloud amount monotonically increases from midnight to early morning (0930

  9. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part I; Low-Level Cloud Macrophysical, Microphysical, and Radiative Properties

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Minnis, Patrick; Xi, Baike

    2005-01-01

    A record of single-layer and overcast low cloud (stratus) properties has been generated using approximately 4000 hours of data collected from January 1997 to December 2002 at the Atmospheric Radiation Measurement (ARM) Southern Great Plains Central Facility (SCF). The cloud properties include liquid-phase and liquid-dominant, mixed-phase, low cloud macrophysical, microphysical, and radiative properties including cloud-base and -top heights and temperatures, and cloud physical thickness derived from a ground-based radar and lidar pair, and rawinsonde sounding; cloud liquid water path (LWP) and content (LWC), and cloud-droplet effective radius (r(sub e)) and number concentration (N) derived from the macrophysical properties and radiometer data; and cloud optical depth (tau), effective solar transmission (gamma), and cloud/top-of-atmosphere albedos (R(sub cldy)/R(sub TOA)) derived from Eppley precision spectral pyranometer measurements. The cloud properties were analyzed in terms of their seasonal, monthly, and hourly variations. In general, more stratus clouds occur during winter and spring than in summer. Cloud-layer altitudes and physical thicknesses were higher and greater in summer than in winter with averaged physical thicknesses of 0.85 km and 0.73 km for day and night, respectively. The seasonal variations of LWP, LWC, N. tau, R(sub cldy), and R(sub TOA) basically follow the same pattern with maxima and minima during winter and summer, respectively. There is no significant variation in mean r(sub e), however, despite a summertime peak in aerosol loading, Although a considerable degree of variability exists, the 6-yr average values of LWP, LWC, r(sub e), N, tau, gamma, R(sub cldy) and R(sub TOA) are 150 gm(exp -2) (138), 0.245 gm(exp -3) (0.268), 8.7 micrometers (8.5), 213 cm(exp -3) (238), 26.8 (24.8), 0.331, 0.672, 0.563 for daytime (nighttime). A new conceptual model of midlatitude continental low clouds at the ARM SGP site has been developed from this study

  10. Vertical Cloud Climatology During TC4 Derived from High-Altitude Aircraft Merged Lidar and Radar Profiles

    NASA Technical Reports Server (NTRS)

    Hlavka, Dennis; Tian, Lin; Hart, William; Li, Lihua; McGill, Matthew; Heymsfield, Gerald

    2009-01-01

    Aircraft lidar works by shooting laser pulses toward the earth and recording the return time and intensity of any of the light returning to the aircraft after scattering off atmospheric particles and/or the Earth s surface. The scattered light signatures can be analyzed to tell the exact location of cloud and aerosol layers and, with the aid of a few optical assumptions, can be analyzed to retrieve estimates of optical properties such as atmospheric transparency. Radar works in a similar fashion except it sends pulses toward earth at a much larger wavelength than lidar. Radar records the return time and intensity of cloud or rain reflection returning to the aircraft. Lidar can measure scatter from optically thin cirrus and aerosol layers whose particles are too small for the radar to detect. Radar can provide reflection profiles through thick cloud layers of larger particles that lidar cannot penetrate. Only after merging the two instrument products can accurate measurements of the locations of all layers in the full atmospheric column be achieved. Accurate knowledge of the vertical distribution of clouds is important information for understanding the Earth/atmosphere radiative balance and for improving weather/climate forecast models. This paper describes one such merged data set developed from the Tropical Composition, Cloud and Climate Coupling (TC4) experiment based in Costa Rica in July-August 2007 using the nadir viewing Cloud Physics Lidar (CPL) and the Cloud Radar System (CRS) on board the NASA ER-2 aircraft. Statistics were developed concerning cloud probability through the atmospheric column and frequency of the number of cloud layers. These statistics were calculated for the full study area, four sub-regions, and over land compared to over ocean across all available flights. The results are valid for the TC4 experiment only, as preferred cloud patterns took priority during mission planning. The TC4 Study Area was a very cloudy region, with cloudy

  11. Action spectra affect variability of the climatology of biologically effective ultraviolet radiation on cloud-free days.

    PubMed

    Grifoni, D; Zipoli, G; Sabatini, F; Messeri, G; Bacci, L

    2013-12-01

    Action spectrum (AS) describes the relative effectiveness of ultraviolet (UV) radiation in producing biological effects and allows spectral UV irradiance to be weighted in order to compute biologically effective UV radiation (UVBE). The aim of this research was to study the seasonal and latitudinal distribution over Europe of daily UVBE doses responsible for various biological effects on humans and plants. Clear sky UV radiation spectra were computed at 30-min time intervals for the first day of each month of the year for Rome, Potsdam and Trondheim using a radiative transfer model fed with climatological data. Spectral data were weighted using AS for erythema, vitamin D synthesis, cataract and photokeratitis for humans, while the generalised plant damage and the plant damage AS were used for plants. The daily UVBE doses for the above-mentioned biological processes were computed and are analysed in this study. The patterns of variation due to season (for each location) and latitude (for each date) resulted as being specific for each adopted AS. The biological implications of these results are briefly discussed highlighting the importance of a specific UVBE climatology for each biological process.

  12. Atmospheric cloud physics laboratory project study

    NASA Technical Reports Server (NTRS)

    Schultz, W. E.; Stephen, L. A.; Usher, L. H.

    1976-01-01

    Engineering studies were performed for the Zero-G Cloud Physics Experiment liquid cooling and air pressure control systems. A total of four concepts for the liquid cooling system was evaluated, two of which were found to closely approach the systems requirements. Thermal insulation requirements, system hardware, and control sensor locations were established. The reservoir sizes and initial temperatures were defined as well as system power requirements. In the study of the pressure control system, fluid analyses by the Atmospheric Cloud Physics Laboratory were performed to determine flow characteristics of various orifice sizes, vacuum pump adequacy, and control systems performance. System parameters predicted in these analyses as a function of time include the following for various orifice sizes: (1) chamber and vacuum pump mass flow rates, (2) the number of valve openings or closures, (3) the maximum cloud chamber pressure deviation from the allowable, and (4) cloud chamber and accumulator pressure.

  13. Probing the climatological impact of a cosmic ray-cloud connection through low-frequency radio observations

    NASA Astrophysics Data System (ADS)

    Magee, Nathan; Kavic, Michael

    2012-01-01

    It has been proposed that cosmic ray events could have a causal relationship with cloud formation rates. Given the weak constraints on the role that cloud formation plays in climate forcing it is essential to understand the role such a relationship could have in shaping the Earth's climate. This issue has been previously investigated in the context of the long-term effect of cosmic ray events on climate. However, in order to establish whether or not such a relationship exists, measurements of short-timescale solar events, individual cosmic ray events, and spatially correlated cloud parameters could be of great significance. Here we propose such a comparison using observations from a pair of radio telescopes arrays, the Long Wavelength Array (LWA) and the Eight-meter-wavelength Transient Array (ETA). These low-frequency radio arrays have a unique ability to simultaneously conduct solar, ionospheric and cosmic rays observations and are thus ideal for such a comparison. We will outline plans for a comparison using data from these instruments, satellite images of cloud formation as well as expected cloud formation rates from numerical models. We present some preliminary results illustrating the efficacy of this type of comparison and discuss future plans to carryout this program.

  14. Temporal and spectral cloud screening of polar winter aerosol optical depth (AOD): impact of homogeneous and inhomogeneous clouds and crystal layers on climatological-scale AODs

    NASA Astrophysics Data System (ADS)

    O'Neill, Norman T.; Baibakov, Konstantin; Hesaraki, Sareh; Ivanescu, Liviu; Martin, Randall V.; Perro, Chris; Chaubey, Jai P.; Herber, Andreas; Duck, Thomas J.

    2016-10-01

    We compared star-photometry-derived, polar winter aerosol optical depths (AODs), acquired at Eureka, Nunavut, Canada, and Ny-Ålesund, Svalbard, with GEOS-Chem (GC) simulations as well as ground-based lidar and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) retrievals over a sampling period of two polar winters. The results indicate significant cloud and/or low-altitude ice crystal (LIC) contamination which is only partially corrected using temporal cloud screening. Spatially homogeneous clouds and LICs that remain after temporal cloud screening represent an inevitable systematic error in the estimation of AOD: this error was estimated to vary from 78 to 210 % at Eureka and from 2 to 157 % at Ny-Ålesund. Lidar analysis indicated that LICs appeared to have a disproportionately large influence on the homogeneous coarse-mode optical depths that escape temporal cloud screening. In principle, spectral cloud screening (to yield fine-mode or submicron AODs) reduces pre-cloud-screened AODs to the aerosol contribution if one assumes that coarse-mode (super-micron) aerosols are a minor part of the AOD. Large, low-frequency differences between these retrieved values and their GC analogue appeared to be often linked to strong, spatially extensive planetary boundary layer events whose presence at either site was inferred from CALIOP profiles. These events were either not captured or significantly underestimated by the GC simulations. High-frequency AOD variations of GC fine-mode aerosols at Ny-Ålesund were attributed to sea salt, while low-frequency GC variations at Eureka and Ny-Ålesund were attributable to sulfates. CALIOP profiles and AODs were invaluable as spatial and temporal redundancy support (or, alternatively, as insightful points of contention) for star photometry retrievals and GC estimates of AOD.

  15. On the Analysis of the Climatology of Cloudiness of the Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Yousef, L. A.; Temimi, M.

    2015-12-01

    This study aims to determine the climatology of cloudiness over the Arabian Peninsula. The determined climatology will assist solar energy resource assessment in the region. The seasonality of cloudiness and its spatial variability will also help guide several cloud seeding operational experiments in the region. Cloud properties from the International Satellite Cloud Climatology Project (ISCCP) database covering the time period from 1983 through 2009 are analyzed. Time series of low, medium, high, and total cloud amounts are investigated, in addition to cloud optical depth and total column water vapor. Initial results show significant decreasing trends in the total and middle cloud amounts, both annually and seasonally, at a 95% confidence interval. The relationship between cloud amounts and climate oscillations known to affect the region is explored. Climate indices exhibiting significant correlations with the total cloud amounts include the Pacific Decadal Oscillation (PDO) index. The study also includes a focus on the United Arab Emirates (UAE), comparing the inferred cloudiness data to in situ rainfall measurements taken from rain gauges across the UAE. To assess the impact of cloudiness on solar power resources in the country, time series of cloud amounts and Direct Normal Irradiance (DNI), obtained from the UAE Solar Atlas, are compared.

  16. The Deep South Clouds & Aerosols project: Improving the modelling of clouds in the Southern Ocean region

    NASA Astrophysics Data System (ADS)

    Morgenstern, Olaf; McDonald, Adrian; Harvey, Mike; Davies, Roger; Katurji, Marwan; Varma, Vidya; Williams, Jonny

    2016-04-01

    Southern-Hemisphere climate projections are subject to persistent climate model biases affecting the large majority of contemporary climate models, which degrade the reliability of these projections, particularly at the regional scale. Southern-Hemisphere specific problems include the fact that satellite-based observations comparisons with model output indicate that cloud occurrence above the Southern Ocean is substantially underestimated, with consequences for the radiation balance, sea surface temperatures, sea ice, and the position of storm tracks. The Southern-Ocean and Antarctic region is generally characterized by an acute paucity of surface-based and airborne observations, further complicating the situation. In recognition of this and other Southern-Hemisphere specific problems with climate modelling, the New Zealand Government has launched the Deep South National Science Challenge, whose purpose is to develop a new Earth System Model which reduces these very large radiative forcing problems associated with erroneous clouds. The plan is to conduct a campaign of targeted observations in the Southern Ocean region, leveraging off international measurement campaigns in this area, and using these and existing measurements of cloud and aerosol properties to improve the representation of clouds in the nascent New Zealand Earth System Model. Observations and model development will target aerosol physics and chemistry, particularly sulphate, sea salt, and non-sulphate organic aerosol, its interactions with clouds, and cloud microphysics. The hypothesis is that the cloud schemes in most GCMs are trained on Northern-Hemisphere data characterized by substantial anthropogenic or terrestrial aerosol-related influences which are almost completely absent in the Deep South.

  17. Assessment of Global Cloud Datasets from Satellites: Project and Database Initiated by the GEWEX Radiation Panel

    NASA Technical Reports Server (NTRS)

    Stubenrauch, C. J.; Rossow, W. B.; Kinne, S.; Ackerman, S.; Cesana, G.; Chepfer, H.; Getzewich, B.; Di Girolamo, L.; Guignard, A.; Heidinger, A.; hide

    2012-01-01

    Clouds cover about 70% of the Earth's surface and play a dominant role in the energy and water cycle of our planet. Only satellite observations provide a continuous survey of the state of the atmosphere over the whole globe and across the wide range of spatial and temporal scales that comprise weather and climate variability. Satellite cloud data records now exceed more than 25 years in length. However, climatologies compiled from different satellite datasets can exhibit systematic biases. Questions therefore arise as to the accuracy and limitations of the various sensors. The Global Energy and Water cycle Experiment (GEWEX) Cloud Assessment, initiated in 2005 by the GEWEX Radiation Panel, provided the first coordinated intercomparison of publically available, standard global cloud products (gridded, monthly statistics) retrieved from measurements of multi-spectral imagers (some with multiangle view and polarization capabilities), IR sounders and lidar. Cloud properties under study include cloud amount, cloud height (in terms of pressure, temperature or altitude), cloud radiative properties (optical depth or emissivity), cloud thermodynamic phase and bulk microphysical properties (effective particle size and water path). Differences in average cloud properties, especially in the amount of high-level clouds, are mostly explained by the inherent instrument measurement capability for detecting and/or identifying optically thin cirrus, especially when overlying low-level clouds. The study of long-term variations with these datasets requires consideration of many factors. A monthly, gridded database, in common format, facilitates further assessments, climate studies and the evaluation of climate models.

  18. NASA/Max Planck Institute Barium Ion Cloud Project.

    NASA Technical Reports Server (NTRS)

    Brence, W. A.; Carr, R. E.; Gerlach, J. C.; Neuss, H.

    1973-01-01

    NASA and the Max Planck Institute for Extraterrestrial Physics (MPE), Munich, Germany, conducted a cooperative experiment involving the release and study of a barium cloud at 31,500 km altitude near the equatorial plane. The release was made near local magnetic midnight on Sept. 21, 1971. The MPE-built spacecraft contained a canister of 16 kg of Ba CuO mixture, a two-axis magnetometer, and other payload instrumentation. The objectives of the experiment were to investigate the interaction of the ionized barium cloud with the ambient medium and to deduce the properties of electric fields in the proximity of the release. An overview of the project is given to briefly summarize the organization, responsibilities, objectives, instrumentation, and operational aspects of the project.

  19. An Overview of the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE)

    NASA Astrophysics Data System (ADS)

    Sellers, P. J.; Hall, F. G.; Asrar, G.; Strebel, D. E.; Murphy, R. E.

    1992-11-01

    and atmospheric parameters and satellite overpasses. The resulting data are held in a single integrated data base and continue to be analyzed by the participating scientists and others. The first two sections of this paper recount the history and scientific background leading up to FIFE; the third and fourth sections review the experiment design, the scientific teams and equipment involved, and the actual execution of the experiment; the fifth section provides an overview of the contents of this special issue; the sixth section summarizes the management and resources of the project; and the last section lists the acknowledgments.

  20. FUSE Team Project on Molecular Hydrogen in Translucent Clouds

    NASA Astrophysics Data System (ADS)

    Snow, Theodore P.

    This Cycle 2 program plans observations of 11 stars (in addition to the original list) as an add-on to our medium project to study molecular hydrogen in translucent clouds. The new stars have been selected on the basis of reddening, known extinction and interstellar line parameters, and inclusion in the comprehensive survey of diffuse interstellar bands being carried out by group member Don York and collaborators (e.g. Snow, Welty et al.).

  1. A 19-Month Climatology of Marine Aerosol-Cloud-Radiation Properties Derived From DOE ARM AMF Deployment at the Azores: Part I: Cloud Fraction and Single-Layered MBL Cloud Properties

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Xi, Baike; Kennedy, Aaron; Minnis, Patrick; Wood, Robert

    2013-01-01

    A 19-month record of total, and single-layered low (0-3 km), middle (3-6 km), and high (> 6 km) cloud fractions (CFs), and the single-layered marine boundary layer (MBL) cloud macrophysical and microphysical properties has been generated from ground-based measurements taken at the ARM Azores site between June 2009 and December 2010. It documents the most comprehensive and longest dataset on marine cloud fraction and MBL cloud properties to date. The annual means of total CF, and single-layered low, middle, and high CFs derived from ARM radar-lidar observations are 0.702, 0.271, 0.01 and 0.106, respectively. More total and single-layered high CFs occurred during winter, while single-layered low CFs were greatest during summer. The diurnal cycles for both total and low CFs are stronger during summer than during winter. The CFs are bimodally distributed in the vertical with a lower peak at approx. 1 km and higher one between 8 and 11 km during all seasons, except summer, when only the low peak occurs. The persistent high pressure and dry conditions produce more single-layered MBL clouds and fewer total clouds during summer, while the low pressure and moist air masses during winter generate more total and multilayered-clouds, and deep frontal clouds associated with midlatitude cyclones.

  2. Projected changes in temperature and precipitation climatology of Central Asia CORDEX Region 8 by using RegCM4.3.5

    NASA Astrophysics Data System (ADS)

    Ozturk, Tugba; Turp, M. Tufan; Türkeş, Murat; Kurnaz, M. Levent

    2017-01-01

    This work investigated projected future changes in seasonal mean air temperature (°C) and precipitation (mm/day) climatology for the three periods of 2011-2040, 2041-2070, and 2071-2100, with respect to the control period of 1971-2000 for the Central Asia domain via regional climate model simulations. In order to investigate the projected changes in near future climate conditions, the Regional Climate Model, RegCM4.3.5 of the International Centre for Theoretical Physics (ICTP) was driven by two different CMIP5 global climate models. The HadGEM2-ES global climate model of the Met Office Hadley Centre and the MPI-ESM-MR global climate model of the Max Planck Institute for Meteorology were downscaled to 50 km for the Coordinated Regional Climate Downscaling Experiment (CORDEX) Region 8. We investigated the seasonal time-scale performance of RegCM4.3.5 in reproducing observed climatology over the domain of the Central Asia by using two different global climate model outputs. For the future climatology of the domain, the regional model projects relatively high warming in the warm season with a decrease in precipitation in almost all parts of the domain. A warming trend is notable, especially for the northern part of the domain during the cold season. The results of our study show that surface air temperatures in the region will increase between 3 °C and about 7 °C on average, according to the emission scenarios for the period of 2071-2100 with respect to past period of 1971-2000. Therefore, the projected warming and decrease in precipitation might adversely affect the ecological and socio-economic systems of this region, which is already a mostly arid and semi-arid environment.

  3. Validation of Long-Term Global Aerosol Climatology Project Optical Thickness Retrievals Using AERONET and MODIS Data

    NASA Technical Reports Server (NTRS)

    Geogdzhayev, Igor V.; Mishchenko, Michael I.

    2015-01-01

    A comprehensive set of monthly mean aerosol optical thickness (AOT) data from coastal and island AErosol RObotic NETwork (AERONET) stations is used to evaluate Global Aerosol Climatology Project (GACP) retrievals for the period 1995-2009 during which contemporaneous GACP and AERONET data were available. To put the GACP performance in broader perspective, we also compare AERONET and MODerate resolution Imaging Spectroradiometer (MODIS) Aqua level-2 data for 2003-2009 using the same methodology. We find that a large mismatch in geographic coverage exists between the satellite and ground-based datasets, with very limited AERONET coverage of open-ocean areas. This is especially true of GACP because of the smaller number of AERONET stations at the early stages of the network development. Monthly mean AOTs from the two over-the-ocean satellite datasets are well-correlated with the ground-based values, the correlation coefficients being 0.81-0.85 for GACP and 0.74-0.79 for MODIS. Regression analyses demonstrate that the GACP mean AOTs are approximately 17%-27% lower than the AERONET values on average, while the MODIS mean AOTs are 5%-25% higher. The regression coefficients are highly dependent on the weighting assumptions (e.g., on the measure of aerosol variability) as well as on the set of AERONET stations used for comparison. Comparison of over-the-land and over-the-ocean MODIS monthly mean AOTs in the vicinity of coastal AERONET stations reveals a significant bias. This may indicate that aerosol amounts in coastal locations can differ significantly from those in adjacent open-ocean areas. Furthermore, the color of coastal waters and peculiarities of coastline meteorological conditions may introduce biases in the GACP AOT retrievals. We conclude that the GACP and MODIS over-the-ocean retrieval algorithms show similar ranges of discrepancy when compared to available coastal and island AERONET stations. The factors mentioned above may limit the performance of the

  4. Validation of Long-Term Global Aerosol Climatology Project Optical Thickness Retrievals Using AERONET and MODIS Data

    NASA Technical Reports Server (NTRS)

    Geogdzhayev, Igor V.; Mishchenko, Michael I.

    2015-01-01

    A comprehensive set of monthly mean aerosol optical thickness (AOT) data from coastal and island AErosol RObotic NETwork (AERONET) stations is used to evaluate Global Aerosol Climatology Project (GACP) retrievals for the period 1995-2009 during which contemporaneous GACP and AERONET data were available. To put the GACP performance in broader perspective, we also compare AERONET and MODerate resolution Imaging Spectroradiometer (MODIS) Aqua level-2 data for 2003-2009 using the same methodology. We find that a large mismatch in geographic coverage exists between the satellite and ground-based datasets, with very limited AERONET coverage of open-ocean areas. This is especially true of GACP because of the smaller number of AERONET stations at the early stages of the network development. Monthly mean AOTs from the two over-the-ocean satellite datasets are well-correlated with the ground-based values, the correlation coefficients being 0.81-0.85 for GACP and 0.74-0.79 for MODIS. Regression analyses demonstrate that the GACP mean AOTs are approximately 17%-27% lower than the AERONET values on average, while the MODIS mean AOTs are 5%-25% higher. The regression coefficients are highly dependent on the weighting assumptions (e.g., on the measure of aerosol variability) as well as on the set of AERONET stations used for comparison. Comparison of over-the-land and over-the-ocean MODIS monthly mean AOTs in the vicinity of coastal AERONET stations reveals a significant bias. This may indicate that aerosol amounts in coastal locations can differ significantly from those in adjacent open-ocean areas. Furthermore, the color of coastal waters and peculiarities of coastline meteorological conditions may introduce biases in the GACP AOT retrievals. We conclude that the GACP and MODIS over-the-ocean retrieval algorithms show similar ranges of discrepancy when compared to available coastal and island AERONET stations. The factors mentioned above may limit the performance of the

  5. A 10-Year Climatology of Cloud Cover and Vertical Distribution Derived from Both Surface and GOES Observations Over the DOE ARM SGP Site

    NASA Technical Reports Server (NTRS)

    Xi, Baike; Dong, Xiquan; Minnis, P.; Khaiyer, M.

    2010-01-01

    Analysis of a decade of ARM radar-lidar and GOES observations at the SGP site reveal that 0.5 and 4-hr averages of the surface cloud fraction correspond closely to 0.5deg and 2.5deg averages of GOES cloudiness, respectively. The long-term averaged surface and GOES cloud fractions agree to within 0.5%. Cloud frequency increases and cloud amount decreases as the temporal and spatial averaging scales increase. Clouds occurred most often during winter and spring. Single-layered clouds account for 61.5% of the total cloud frequency. There are distinct bimodal vertical distributions of clouds with a lower peak around 1 km and an upper one that varies from 7.5 to 10.8 km between winter and summer, respectively. The frequency of occurrence for nighttime GOES high-cloud tops agree well with the surface observations, but are underestimated during the day.

  6. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Key, J. R.; Maslanik, J. A.

    1988-01-01

    The principal objectives of this project are: (1) to develop suitable validation data sets to evaluate the effectiveness of the International Satellite Cloud Climatology Project (ISCCP) operational algorithm for cloud retrieval in polar regions and to validate model simulations of polar cloud cover; (2) to identify limitations of current procedures for varying atmospheric surface conditions, and to explore potential means to remedy them using textural classifiers; and (3) to compare synoptic cloud data from a control run experiment of the GISS climate model II with typical observed synoptic cloud patterns.

  7. Determination of cloud parameters from infrared sounder data

    NASA Technical Reports Server (NTRS)

    Yeh, H.-Y. M.

    1984-01-01

    The World Climate Research Programme (WCRP) plan is concerned with the need to develop a uniform global cloud climatology as part of a broad research program on climate processes. The International Satellite Cloud Climatology Project (ISCCP) has been approved as the first project of the WCRP. The ISCCP has the basic objective to collect and analyze satellite radiance data to infer the global distribution of cloud radiative properties in order to improve the modeling of cloud effects on climate. Research is conducted to explore an algorithm for retrieving cloud properties by utilizing the available infrared sounder data from polar-orbiting satellites. A numerical method is developed for computing cloud top heights, amount, and emissivity on the basis of a parameterized infrared radiative transfer equation for cloudy atmospheres. Theoretical studies were carried out by considering a synthetic atmosphere.

  8. Determination of cloud parameters from infrared sounder data

    NASA Technical Reports Server (NTRS)

    Yeh, H.-Y. M.

    1984-01-01

    The World Climate Research Programme (WCRP) plan is concerned with the need to develop a uniform global cloud climatology as part of a broad research program on climate processes. The International Satellite Cloud Climatology Project (ISCCP) has been approved as the first project of the WCRP. The ISCCP has the basic objective to collect and analyze satellite radiance data to infer the global distribution of cloud radiative properties in order to improve the modeling of cloud effects on climate. Research is conducted to explore an algorithm for retrieving cloud properties by utilizing the available infrared sounder data from polar-orbiting satellites. A numerical method is developed for computing cloud top heights, amount, and emissivity on the basis of a parameterized infrared radiative transfer equation for cloudy atmospheres. Theoretical studies were carried out by considering a synthetic atmosphere.

  9. A study of cloud-generated radiative heating and its generation of available potential energy. I - Theoretical background. II - Results for a climatological zonal mean January

    NASA Technical Reports Server (NTRS)

    Stuhlmann, R.; Smith, G. L.

    1988-01-01

    The effect of radiative heating and cooling by clouds on the available potential energy (APE) is theoretically discussed. It is shown that the cloud radiative contribution to the generation of APE is determined by the net cloud radiative heating and the efficiency factor, which is a function of the temperature distribution of the atmosphere. Results are presented for low and middle cloud effects for three atmospheric layers. Cloud radiative heating is found to be a single function of cloud optical thickness for all classes designed in terms of cloud top heights and optical thickness. Low clouds at low latitudes destroy APE an midclouds generate APE. A concept is developed to relate the cloud radiative heating to cloud heights and optical depths. Cloud-generated radiative heating is computed for January zonal mean conditions for low and midclouds. For both cases, the strongest influence is found in the low troposphere, with marked differences in signs and magnitudes. At extratropical latitudes, both cloud classes generate net radiative cooling. In the tropics, the effect of low cloud changes from net cooling to the net heating as the optical thickness increases, and midclouds cause net heating. A mechanism is described whereby this dependence produces a strong positive feedback effect on the development of SST anomalies in the tropical oceans.

  10. A study of cloud-generated radiative heating and its generation of available potential energy. I - Theoretical background. II - Results for a climatological zonal mean January

    NASA Technical Reports Server (NTRS)

    Stuhlmann, R.; Smith, G. L.

    1988-01-01

    The effect of radiative heating and cooling by clouds on the available potential energy (APE) is theoretically discussed. It is shown that the cloud radiative contribution to the generation of APE is determined by the net cloud radiative heating and the efficiency factor, which is a function of the temperature distribution of the atmosphere. Results are presented for low and middle cloud effects for three atmospheric layers. Cloud radiative heating is found to be a single function of cloud optical thickness for all classes designed in terms of cloud top heights and optical thickness. Low clouds at low latitudes destroy APE an midclouds generate APE. A concept is developed to relate the cloud radiative heating to cloud heights and optical depths. Cloud-generated radiative heating is computed for January zonal mean conditions for low and midclouds. For both cases, the strongest influence is found in the low troposphere, with marked differences in signs and magnitudes. At extratropical latitudes, both cloud classes generate net radiative cooling. In the tropics, the effect of low cloud changes from net cooling to the net heating as the optical thickness increases, and midclouds cause net heating. A mechanism is described whereby this dependence produces a strong positive feedback effect on the development of SST anomalies in the tropical oceans.

  11. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    NASA Technical Reports Server (NTRS)

    Starr, David O'C.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction. The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  12. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    NASA Technical Reports Server (NTRS)

    Starr, David OC.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric; Khvorostyanov, Vitaly; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction (Browning et al, 1994). The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  13. Detect signals of interdecadal climate variations from an enhanced suite of reconstructed precipitation products since 1850 using the historical station data from Global Historical Climatology Network and the dynamical patterns derived from Global Precipitation Climatology Project

    NASA Astrophysics Data System (ADS)

    Shen, S. S.

    2015-12-01

    This presentation describes the detection of interdecadal climate signals in a newly reconstructed precipitation data from 1850-present. Examples are on precipitation signatures of East Asian Monsoon (EAM), Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillations (AMO). The new reconstruction dataset is an enhanced edition of a suite of global precipitation products reconstructed by Spectral Optimal Gridding of Precipitation Version 1.0 (SOGP 1.0). The maximum temporal coverage is 1850-present and the spatial coverage is quasi-global (75S, 75N). This enhanced version has three different temporal resolutions (5-day, monthly, and annual) and two different spatial resolutions (2.5 deg and 5.0 deg). It also has a friendly Graphical User Interface (GUI). SOGP uses a multivariate regression method using an empirical orthogonal function (EOF) expansion. The Global Precipitation Climatology Project (GPCP) precipitation data from 1981-20010 are used to calculate the EOFs. The Global Historical Climatology Network (GHCN) gridded data are used to calculate the regression coefficients for reconstructions. The sampling errors of the reconstruction are analyzed according to the number of EOF modes used in the reconstruction. Our reconstructed 1900-2011 time series of the global average annual precipitation shows a 0.024 (mm/day)/100a trend, which is very close to the trend derived from the mean of 25 models of the CMIP5 (Coupled Model Intercomparison Project Phase 5). Our reconstruction has been validated by GPCP data after 1979. Our reconstruction successfully displays the 1877 El Nino (see the attached figure), which is considered a validation before 1900. Our precipitation products are publically available online, including digital data, precipitation animations, computer codes, readme files, and the user manual. This work is a joint effort of San Diego State University (Sam Shen, Gregori Clarke, Christian Junjinger, Nancy Tafolla, Barbara Sperberg, and

  14. Estimating errors in fractional cloud cover obtained with infrared threshold methods

    SciTech Connect

    Chang, Fu-Lung; Coakley, J.A. Jr. )

    1993-05-20

    The authors address the question of detecting cloud coverage from satellite imagery. The International Satellite Cloud Climatology Project (ISCCP), and NIMBUS-7 have constructed cloud climatologies, but they differ substantially in the global mean cloud cover. Here the authors address problems in the application of threshold methods to the infrared detection of cloud cover. They look in particular at single-layered cloud cover, and compare the threshold IR detection method with a spatial coherence method. One of the problems is that the pixel size of satellite imagery, namely 4-8km on a side is not particularly small compared to cloud features, or even breaks in cloud cover, and there can be severe error in estimating cloud cover because of this difficulty.

  15. Computing and Partitioning Cloud Feedbacks using Cloud Property Histograms

    NASA Astrophysics Data System (ADS)

    Zelinka, M. D.; Klein, S. A.; Hartmann, D. L.

    2011-12-01

    In this study we propose a novel technique for computing cloud feedbacks using histograms of cloud fraction as joint functions of cloud top pressure and optical depth generated by the International Satellite Cloud Climatology Project (ISCCP) simulator, which was incorporated into the climate models that took part in the Cloud Feedback Model Intercomparison Project. We use a radiative transfer model to compute top of atmosphere (TOA) flux sensitivities to cloud fraction perturbations in each bin of the ISCCP simulator histogram, which we refer to as a cloud radiative kernel. Multiplying the cloud radiative kernel histogram with the histogram of actual cloud top fraction changes per unit of global warming simulated by each model produces an estimate of cloud feedback. Both the spatial structures and globally integrated values of cloud feedbacks computed in this manner agree remarkably well with those computed by adjusting the change in cloud radiative forcing for clear-sky effects as in Soden et al. (2008). The technique allows us to quantitatively partition cloud feedbacks into contributions from changes in cloud amount, height, and optical depth. We show that rising clouds are the dominant contributor to the positive LW cloud feedback, and that the extra-tropical contribution is approximately 70% as large as the tropical contribution. In the ensemble mean, the positive impact of rising clouds is 50% larger than the negative impact of reductions in cloud amount on LW cloud feedback, but the degree to which reductions in cloud fraction offset the effect of rising clouds varies considerably across models. In contrast, reductions in cloud fraction make a large and virtually unopposed positive contribution to SW cloud feedback, though the inter-model spread is greater than for any other individual feedback component. In general, models exhibiting greater reductions in subtropical marine boundary layer cloudiness tend to have larger positive SW cloud feedbacks, in

  16. Assessment of Projected Changes in Temperature and Precipitation Climatology over the CORDEX-Region 9 via Multi-Model Ensemble Mean of CMIP5 Models

    NASA Astrophysics Data System (ADS)

    Turp, M. Tufan; Ozturk, Tugba; Kurnaz, M. Levent

    2016-04-01

    In this study, we conduct a multi-model ensemble mean approach in order to investigate of projected changes in fundamental climate variables (i.e. mean air temperature, minimum temperature, maximum temperature, and precipitation total) over the CORDEX-Australasia domain based on the outputs of various coupled global climate models (GCMs) participating in the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project (CMIP5). In this respect, in order to analyze projected future changes in temperature and precipitation climatology, seasonal averages, and inter-annual variability over the Australasia (known as Region 9) domain, where is one of fourteen domains of the Coordinated Regional Climate Downscaling Experiment (CORDEX), we focus on historical, RCP4.5 and RCP8.5 experiments of the GCMs for reference- (1981 - 2000), near- (2016 - 2035), mid- (2046 - 2065), and long-term (2081 - 2100), respectively. This research has been supported by Boǧaziçi University Research Fund Grant Number 10421.

  17. The MACHO Project: Status Report on the Magellanic Clouds.

    NASA Astrophysics Data System (ADS)

    Vandehei, T.; Griest, K.; Alcock, C.; Alves, D.; Cook, K.; Minniti, D.; Marshall, S.; Allsman, R.; Axelrod, T.; Freeman, K.; Peterson, B.; Rodgers, A.; Pratt, M.; Becker, A.; Stubbs, C.; Tomaney, A. B.; Lehner, M.; Bennett, D.; Nelson, C.; Quinn, P.; Sutherland, W.; Welch, D.

    1998-05-01

    The MACHO Project is a search for dark matter in the form of massive compact halo objects (MACHOs). Photometric monitoring of tens of millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge is used to search for these rare gravitational microlensing events caused by these otherwise invisible objects. An analysis of 4 years of LMC data on 12 million stars and 5 years of SMC data on 3 million stars is currently underway. We present preliminary results of this analysis which reveal about 15 candidate microlensing events in the LMC and 1 event in the SMC. We also present our microlensing detection efficiency calculation pipeline. The accurate determination of our detection efficiency is key in estimating the MACHO contribution to the dark matter in the halo. The efficiency pipeline uses data from the MACHO Project's ground based survey and from HST observations of MACHO fields to determine the true color and luminosity distribution of LMC source stars. Artificial microlensing events are then inserted into the underlying source distribution, image sequences are created from a wide sample of real image conditions and detection efficiencies are determined using our standard reduction pipeline. The full calculation of our efficiencies requires the creation, reduction and analysis of 322 Gbytes of artificial image data and is currently underway.

  18. The ESA Cloud CCI project: Generation of Multi Sensor consistent Cloud Properties with an Optimal Estimation Based Retrieval Algorithm

    NASA Astrophysics Data System (ADS)

    Jerg, M.; Stengel, M.; Hollmann, R.; Poulsen, C.

    2012-04-01

    The ultimate objective of the ESA Climate Change Initiative (CCI) Cloud project is to provide long-term coherent cloud property data sets exploiting and improving on the synergetic capabilities of past, existing, and upcoming European and American satellite missions. The synergetic approach allows not only for improved accuracy and extended temporal and spatial sampling of retrieved cloud properties better than those provided by single instruments alone but potentially also for improved (inter-)calibration and enhanced homogeneity and stability of the derived time series. Such advances are required by the scientific community to facilitate further progress in satellite-based climate monitoring, which leads to a better understanding of climate. Some of the primary objectives of ESA Cloud CCI Cloud are (1) the development of inter-calibrated radiance data sets, so called Fundamental Climate Data Records - for ESA and non ESA instruments through an international collaboration, (2) the development of an optimal estimation based retrieval framework for cloud related essential climate variables like cloud cover, cloud top height and temperature, liquid and ice water path, and (3) the development of two multi-annual global data sets for the mentioned cloud properties including uncertainty estimates. These two data sets are characterized by different combinations of satellite systems: the AVHRR heritage product comprising (A)ATSR, AVHRR and MODIS and the novel (A)ATSR - MERIS product which is based on a synergetic retrieval using both instruments. Both datasets cover the years 2007-2009 in the first project phase. ESA Cloud CCI will also carry out a comprehensive validation of the cloud property products and provide a common data base as in the framework of the Global Energy and Water Cycle Experiment (GEWEX). The presentation will give an overview of the ESA Cloud CCI project and its goals and approaches and then continue with results from the Round Robin algorithm

  19. QUANTIFYING OBSERVATIONAL PROJECTION EFFECTS USING MOLECULAR CLOUD SIMULATIONS

    SciTech Connect

    Beaumont, Christopher N.; Offner, Stella S.R.; Shetty, Rahul; Glover, Simon C. O.; Goodman, Alyssa A.

    2013-11-10

    The physical properties of molecular clouds are often measured using spectral-line observations, which provide the only probes of the clouds' velocity structure. It is hard, though, to assess whether and to what extent intensity features in position-position-velocity (PPV) space correspond to 'real' density structures in position-position-position (PPP) space. In this paper, we create synthetic molecular cloud spectral-line maps of simulated molecular clouds, and present a new technique for measuring the reality of individual PPV structures. Using a dendrogram algorithm, we identify hierarchical structures in both PPP and PPV space. Our procedure projects density structures identified in PPP space into corresponding intensity structures in PPV space and then measures the geometric overlap of the projected structures with structures identified from the synthetic observation. The fractional overlap between a PPP and PPV structure quantifies how well the synthetic observation recovers information about the three-dimensional structure. Applying this machinery to a set of synthetic observations of CO isotopes, we measure how well spectral-line measurements recover mass, size, velocity dispersion, and virial parameter for a simulated star-forming region. By disabling various steps of our analysis, we investigate how much opacity, chemistry, and gravity affect measurements of physical properties extracted from PPV cubes. For the simulations used here, which offer a decent, but not perfect, match to the properties of a star-forming region like Perseus, our results suggest that superposition induces a ∼40% uncertainty in masses, sizes, and velocity dispersions derived from {sup 13}CO (J = 1-0). As would be expected, superposition and confusion is worst in regions where the filling factor of emitting material is large. The virial parameter is most affected by superposition, such that estimates of the virial parameter derived from PPV and PPP information typically disagree

  20. A Study to Investigate Cloud Feedback Processes and Evaluate GCM Cloud Variations Using Statistical Cloud Property Composites From ARM Data

    SciTech Connect

    George Tselioudis

    2009-08-11

    cloud layering information into the context of large-scale dynamical regimes, such information can be used to study interactions among cloud vertical distributions and dynamical and microphysical processes and to evaluate the ability of models to simulate those interactions. The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program has established several Climate Research Facilities (ACRF) that provide continuous, long-term observations of clouds and radiation. ARM, with its overall goal of improving the treatment of radiation and clouds in climate models has provided unique observing systems for accelerating progress on the representation of cloud processes. In this project, six and a half years (January 1998 to June 2004) of cloud observations collected at the Southern Great Plains (SGP) Oklahoma ACRF were used to produce a cloud-type climatology. The climatology provides cloud amounts for seven different cloud types as well as information on the detailed structure of multi-layer cloud occurrences. Furthermore, the European Centre for Medium-Range Weather Forecasts (ECMWF) model output was used to define the dynamic regimes present during the observations of the cloud conditions by the vertically pointing radars at the SGP ACRF. The cloud-type climatology and the ECMWF SGP data set were then analyzed to examine and map dynamical conditions that favor the creation of single-layer versus multi-layer cloud structures as well as dynamical conditions that favor the occurrence of drizzle in continental stratus clouds. In addition, output from the ECMWF weather model forecasts was analyzed with the objective to compare model and radar derived cloud type statistics, in order to identify the major model deficiencies in cloud vertical distribution and map their seasonal variations. The project included two primary goals. The first was to create a cloud type climatology over the Southern Great Planes site that will show how cloud vertical distribution

  1. Time-cumulated visible and infrared histograms used as descriptor of cloud cover

    NASA Technical Reports Server (NTRS)

    Seze, G.; Rossow, W.

    1987-01-01

    To study the statistical behavior of clouds for different climate regimes, the spatial and temporal stability of VIS-IR bidimensional histograms is tested. Also, the effect of data sampling and averaging on the histogram shapes is considered; in particular the sampling strategy used by the International Satellite Cloud Climatology Project is tested.

  2. Projected Regime Shift in Arctic Cloud and Water Vapor Feedbacks

    NASA Technical Reports Server (NTRS)

    Chen, Yonghua; Miller, James R.; Francis, Jennifer; Russel, Gary L.

    2011-01-01

    The Arctic climate is changing faster than any other large-scale region on Earth. A variety of positive feedback mechanisms are responsible for the amplification, most of which are linked with changes in snow and ice cover, surface temperature (T(sub s)), atmospheric water vapor (WV), and cloud properties. As greenhouse gases continue to accumulate in the atmosphere, air temperature and water vapor content also increase, leading to a warmer surface and ice loss, which further enhance evaporation and WV. Many details of these interrelated feedbacks are poorly understood, yet are essential for understanding the pace and regional variations in future Arctic change. We use a global climate model (Goddard Institute for Space Studies, Atmosphere-Ocean Model) to examine several components of these feedbacks, how they vary by season, and how they are projected to change through the 21st century. One positive feedback begins with an increase in T(sub s) that produces an increase in WV, which in turn increases the downward longwave flux (DLF) and T(sub s), leading to further evaporation. Another associates the expected increases in cloud cover and optical thickness with increasing DLF and T(sub s). We examine the sensitivities between DLF and other climate variables in these feedbacks and find that they are strongest in the non-summer seasons, leading to the largest amplification in Ts during these months. Later in the 21st century, however, DLF becomes less sensitive to changes in WV and cloud optical thickness, as they cause the atmosphere to emit longwave radiation more nearly as a black body. This regime shift in sensitivity implies that the amplified pace of Arctic change relative to the northern hemisphere could relax in the future.

  3. Projected Regime Shift in Arctic Cloud and Water Vapor Feedbacks

    NASA Technical Reports Server (NTRS)

    Chen, Yonghua; Miller, James R.; Francis, Jennifer; Russel, Gary L.

    2011-01-01

    The Arctic climate is changing faster than any other large-scale region on Earth. A variety of positive feedback mechanisms are responsible for the amplification, most of which are linked with changes in snow and ice cover, surface temperature (T(sub s)), atmospheric water vapor (WV), and cloud properties. As greenhouse gases continue to accumulate in the atmosphere, air temperature and water vapor content also increase, leading to a warmer surface and ice loss, which further enhance evaporation and WV. Many details of these interrelated feedbacks are poorly understood, yet are essential for understanding the pace and regional variations in future Arctic change. We use a global climate model (Goddard Institute for Space Studies, Atmosphere-Ocean Model) to examine several components of these feedbacks, how they vary by season, and how they are projected to change through the 21st century. One positive feedback begins with an increase in T(sub s) that produces an increase in WV, which in turn increases the downward longwave flux (DLF) and T(sub s), leading to further evaporation. Another associates the expected increases in cloud cover and optical thickness with increasing DLF and T(sub s). We examine the sensitivities between DLF and other climate variables in these feedbacks and find that they are strongest in the non-summer seasons, leading to the largest amplification in Ts during these months. Later in the 21st century, however, DLF becomes less sensitive to changes in WV and cloud optical thickness, as they cause the atmosphere to emit longwave radiation more nearly as a black body. This regime shift in sensitivity implies that the amplified pace of Arctic change relative to the northern hemisphere could relax in the future.

  4. Implications of the Observed Mesoscale Variations of Clouds for Earth's Radiation Budget

    NASA Technical Reports Server (NTRS)

    Rossow, William B.; Delo, Carl; Cairns, Brian; Hansen, James E. (Technical Monitor)

    2001-01-01

    The effect of small-spatial-scale cloud variations on radiative transfer in cloudy atmospheres currently receives a lot of research attention, but the available studies are not very clear about which spatial scales are important and report a very large range of estimates of the magnitude of the effects. Also, there have been no systematic investigations of how to measure and represent these cloud variations. We exploit the cloud climatology produced by the International Satellite Cloud Climatology Project (ISCCP) to: (1) define and test different methods of representing cloud variation statistics, (2) investigate the range of spatial scales that should be included, (3) characterize cloud variations over a range of space and time scales covering mesoscale (30 - 300 km, 3-12 hr) into part of the lower part of the synoptic scale (300 - 3000 km, 1-30 days), (4) obtain a climatology of the optical thickness, emissivity and cloud top temperature variability of clouds that can be used in weather and climate GCMS, together with the parameterization proposed by Cairns et al. (1999), to account for the effects of small-scale cloud variations on radiative fluxes, and (5) evaluate the effect of observed cloud variations on Earth's radiation budget. These results lead to the formulation of a revised conceptual model of clouds for use in radiative transfer calculations in GCMS. The complete variability climatology can be obtained from the ISCCP Web site at http://isccp.giss.nasa.gov.

  5. CMIP5 Multi-Model Projection of the Changes in Air Temperature and Precipitation Climatology over the CORDEX-Australasia Domain under the RCP2.6 Scenario

    NASA Astrophysics Data System (ADS)

    Turp, M. Tufan; Kurnaz, M. Levent

    2017-04-01

    After the Paris Agreement, the studies considering the possible impacts of climate change with the high-level mitigation efforts have become very crucial. In this study, the multi-model ensemble approach was conducted in order to investigate the projected changes in air temperature and precipitation climatology over the CORDEX-Australasia domain based on the outputs of various coupled global climate models (GCMs) participating in the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project (CMIP5). In this respect, seasonal changes were analyzed by using the fundamental climate variables (i.e. mean air temperature, minimum air temperature, maximum air temperature, and precipitation). Historical and RCP2.6 experiments of the GCMs were evaluated for baseline- (1986-2005), near- (2016-2035), mid- (2046-2065), and long-term (2081-2100), respectively. Acknowledgement: This research has been supported by Bogazici University Research Fund Grant Number 12220.

  6. Comparative climatology of four marine stratocumulus regimes

    NASA Technical Reports Server (NTRS)

    Hanson, Howard P.

    1990-01-01

    The climatology of marine stratocumulus (MSc) cloud regimes off the west coasts of California, Peru, Morocco, and Angola are examined. Long-term, annual averages are presented for several quantities of interest in the four MSc regimes. The climatologies were constructed using the Comprehensive Ocean-Atmosphere Data Set (COADS). A 40 year time series of observations was extracted for 32 x 32 deg analysis domains. The data were taken from the monthly-averaged, 2 deg product. The resolution of the analysis is therefore limited to scales of greater than 200 km with submonthly variability not resolved. The averages of total cloud cover, sea surface temperature, and surface pressure are presented.

  7. The NOAA Big Data Project: NEXRAD on the Cloud

    NASA Astrophysics Data System (ADS)

    Gold, A.; Weber, J.

    2015-12-01

    This past April, the US National Oceanic and Atmospheric Administration (NOAA) made headlines when it entered into a research agreement with Amazon Web Services (AWS) to explore sustainable models to increase the output of open NOAA data. Publicly available NOAA data drives multi-billion dollar industries and critical research efforts. Under this new agreement, AWS and its Data Alliance collaborators are looking at ways to push more NOAA data to the cloud and build an ecosystem of innovation around it. In this presentation, we will provide a brief overview of the NOAA Big Data Project and the AWS Data Alliance, then dive into a specific example of data that has been made available (high resolution Doppler radar from the NEXRAD system) and early use cases.

  8. The NOAA Big Data Project: NEXRAD on the Cloud

    NASA Astrophysics Data System (ADS)

    Sundwall, Jed; Bouffler, Brendan

    2016-04-01

    Last year, the US National Oceanic and Atmospheric Administration (NOAA) made headlines when it entered into a research agreement with Amazon Web Services (AWS) to explore sustainable models to increase the output of open NOAA data. Publicly available NOAA data drives multi-billion dollar industries and critical research efforts. Under this new agreement, AWS and its Data Alliance collaborators are looking at ways to push more NOAA data to the cloud and build an ecosystem of innovation around it. In this presentation, we will provide a brief overview of the NOAA Big Data Project and the AWS Data Alliance, then dive into a specific example of data that has been made available (high resolution Doppler radar from the NEXRAD system) and early use cases.

  9. Decadal Variability of Clouds and Comparison with Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Su, H.; Shen, T. J.; Jiang, J. H.; Yung, Y. L.

    2014-12-01

    An apparent climate regime shift occurred around 1998/1999, when the steady increase of global-mean surface temperature appeared to hit a hiatus. Coherent decadal variations are found in atmospheric circulation and hydrological cycles. Using 30-year cloud observations from the International Satellite Cloud Climatology Project, we examine the decadal variability of clouds and associated cloud radiative effects on surface warming. Empirical Orthogonal Function analysis is performed. After removing the seasonal cycle and ENSO signal in the 30-year data, we find that the leading EOF modes clearly represent a decadal variability in cloud fraction, well correlated with the indices of Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO). The cloud radiative effects associated with decadal variations of clouds suggest a positive cloud feedback, which would reinforce the global warming hiatus by a net cloud cooling after 1998/1999. Climate model simulations driven by observed sea surface temperature are compared with satellite observed cloud decadal variability. Copyright:

  10. Toward a Diurnal Climatology of Cold-Season Turbulence Statistics in Continental Stratocumulus as Observed by the Atmospheric Radiation Millimeter- Wavelength Cloud Radars

    SciTech Connect

    Mechem, D.B.; Kogan, Y.L.; Childers, M.E.; Donner, K.M.

    2005-03-18

    Numerous observational studies of marine stratocumulus have demonstrated a pronounced diurnal cycle. At night, longwave flux divergence at the top of the cloud drives negatively buoyant eddies that tend to keep the boundary layer well mixed. During the day, solar absorption by the cloud tends to reduce the turbulent intensity and often decouples the planetary boundary layer (PBL) into cloud- and sub-cloud circulations. The delicate balance between turbulent intensity, entrainment, and fluxes dictates cloud geometry and persistence, which can significantly impact the shortwave radiation budget. Millimeter-wavelength cloud radars (MMCRs) have been used to study the turbulent structure of boundary layer stratocumulus (e.g. Frisch et al. 1995; Kollias and Albrecht 2000). Analysis is confined to nondrizzling or lightly drizzling cloud systems for which precipitation contamination is negligible. Under such assumptions the Doppler velocity field becomes a proxy for vertical velocity. Prior research has mainly consisted of a few case studies of specific cloud systems using radar scan strategies optimized for this particular cloud type. The MMCR operating at the Southern Great Plains Atmospheric Radiation Measurement Climate Research Facility is broadly configured to be able to detect many different cloud types over a broad range of reflectivities and altitudes, so it is not specifically optimized for PBL clouds. Being in more-or-less continuous operation since the end of 1996, it does, however, have the advantage of long data coverage, which suggests that statistically significant measures of the diurnal cycle of turbulence should be attainable. This abstract summarizes the first few steps toward this goal, using 7 months of cold season MMCR data.

  11. Clouds

    NASA Image and Video Library

    2010-09-14

    Clouds are common near the north polar caps throughout the spring and summer. The clouds typically cause a haze over the extensive dune fields. This image from NASA Mars Odyssey shows the edge of the cloud front.

  12. Climatology of precipitating convective clouds in ERA-Interim derived from the Emanuel and Živković-Rothman parameterisation scheme

    NASA Astrophysics Data System (ADS)

    Philipp, Anne; Seibert, Petra

    2016-04-01

    The convective parameterisation scheme of Emanuel and Živković-Rothman (1999) was designed to represent cumulus convection with a special focus on convective water fluxes. This scheme is implemented in the Lagrangian particle transport and dispersion model FLEXPART (FLEXible PARTicle dispersion model, http://flexpart.eu) to calculate a redistribution matrix used for the transport simulation. In order to improve the wet scavenging through convective clouds in this model, we are statistically evaluating a global data set of cloud base and cloud top heights of precipitating clouds derived from the EZ99 scheme and based on ECMWF's ERA-Interim data. They have a spectral resolution of about 80 km and 60 vertical levels available every 6 hours. The results will be evaluated as a function of season and geographical region.

  13. Smart Climatology Applications for Undersea Warfare

    DTIC Science & Technology

    2008-09-01

    project specifications. Green shading indicates resolution finer than 1 degree, global domain, and at least a 30- year period. Table from World...climatologies. 1. Generalized Digital Environmental Model Ocean Climatology Over 100 years worth of ocean observations are available in the form of various...R. Reynolds, R. Jenne, and D. Joseph, 1996: The NCEP/NCAR 40- year re-analysis project . Bull. Am. Meteorol. Soc., 77, 437-471. Kistler, R., and Co

  14. Comparison between SAGE II and ISCCP high-level clouds. 2: Locating clouds tops

    NASA Technical Reports Server (NTRS)

    Liao, Xiaohan; Rossow, William B.; Rind, David

    1995-01-01

    A comparison is made of the vertical distribution of high-level cloud tops derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements and from the International Satellite Cloud Climatology Project (ISCCP) for all Julys and Januarys in 1985 to 1990. The results suggest that ISCCP overestimates the pressure of high-level clouds by up to 50-150 mbar, particularly at low latitudes. This is caused by the frequent presence of clouds with diffuse tops (greater than 50% time when cloudy events are observed). The averaged vertical extent of the diffuse top is about 1.5 km. At midlatitudes where the SAGE II and ISCCP cloud top pressure agree best, clouds with distinct tops reach a maximum relative proportion of the total level cloud amount (about 30-40%), and diffuse-topped clouds are reduced to their minimum (30-40%). The ISCCP-defined cloud top pressure should be regarded not as the material physical height of the clouds but as the level which emits the same infrared radiance as observed. SAGE II and ISCCP cloud top pressures agree for clouds with distinct tops. There is also an indication that the cloud top pressures of optically thin clouds not overlying thicker clouds are poorly estimated by ISCCP at middle latitudes. The average vertical extent of these thin clouds is about 2.5 km.

  15. Comparison between SAGE II and ISCCP high-level clouds. 2: Locating clouds tops

    NASA Technical Reports Server (NTRS)

    Liao, Xiaohan; Rossow, William B.; Rind, David

    1995-01-01

    A comparison is made of the vertical distribution of high-level cloud tops derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements and from the International Satellite Cloud Climatology Project (ISCCP) for all Julys and Januarys in 1985 to 1990. The results suggest that ISCCP overestimates the pressure of high-level clouds by up to 50-150 mbar, particularly at low latitudes. This is caused by the frequent presence of clouds with diffuse tops (greater than 50% time when cloudy events are observed). The averaged vertical extent of the diffuse top is about 1.5 km. At midlatitudes where the SAGE II and ISCCP cloud top pressure agree best, clouds with distinct tops reach a maximum relative proportion of the total level cloud amount (about 30-40%), and diffuse-topped clouds are reduced to their minimum (30-40%). The ISCCP-defined cloud top pressure should be regarded not as the material physical height of the clouds but as the level which emits the same infrared radiance as observed. SAGE II and ISCCP cloud top pressures agree for clouds with distinct tops. There is also an indication that the cloud top pressures of optically thin clouds not overlying thicker clouds are poorly estimated by ISCCP at middle latitudes. The average vertical extent of these thin clouds is about 2.5 km.

  16. Creating a Rackspace and NASA Nebula compatible cloud using the OpenStack project (Invited)

    NASA Astrophysics Data System (ADS)

    Clark, R.

    2010-12-01

    NASA and Rackspace have both provided technology to the OpenStack that allows anyone to create a private Infrastructure as a Service (IaaS) cloud using open source software and commodity hardware. OpenStack is designed and developed completely in the open and with an open governance process. NASA donated Nova, which powers the compute portion of NASA Nebula Cloud Computing Platform, and Rackspace donated Swift, which powers Rackspace Cloud Files. The project is now in continuous development by NASA, Rackspace, and hundreds of other participants. When you create a private cloud using Openstack, you will have the ability to easily interact with your private cloud, a government cloud, and an ecosystem of public cloud providers, using the same API.

  17. Analysis of Cassegrain Cloud Profiling Radar Antenna with Arbitrary Projected Apertures

    NASA Technical Reports Server (NTRS)

    Hussein, Z.; Im, E.

    2000-01-01

    A millimeter wave Cassegrain dual-reflector rada antenna (94GHz) with super-quadric projected aperture boundaries concept, that includes sub-reflector blockage effect, is evaluated for the spaceborne radar measurement of the vertical cloud profile structure.

  18. Analysis of Cassegrain Cloud Profiling Radar Antenna with Arbitrary Projected Apertures

    NASA Technical Reports Server (NTRS)

    Hussein, Z.; Im, E.

    2000-01-01

    A millimeter wave Cassegrain dual-reflector rada antenna (94GHz) with super-quadric projected aperture boundaries concept, that includes sub-reflector blockage effect, is evaluated for the spaceborne radar measurement of the vertical cloud profile structure.

  19. Subvisual-thin cirrus lidar dataset for satellite verification and climatological research

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Cho, Byung S.

    1992-01-01

    A polarization (0.694 microns wavelength) lidar dataset for subvisual and thin (bluish-colored) cirrus clouds is drawn from project FIRE (First ISCCP Regional Experiment) extended time observations. The clouds are characterized by their day-night visual appearance; base, top, and optical midcloud heights and temperatures; measured physical and estimated optical cloud thicknesses; integrated linear depolarization ratios; and derived k/2 eta ratios. A subset of the data supporting 30 NOAA polar-orbiting satellite overpasses is given in tabular form to provide investigators with the means to test cloud retrieval algorithms and establish the limits of cirrus detectability from satellite measurements under various conditions. Climatologically, subvisual-thin cirrus appear to be higher, colder, and more strongly depolarizing than previously reported multilatitude cirrus, although similar k/2 eta that decrease with height and temperature are found.

  20. The Climatology of Hailstone Embryos.

    NASA Astrophysics Data System (ADS)

    Knight, Nancy C.

    1981-07-01

    Data on hailstone embryo types, using a broad classification as graupel or frozen drops, are presented from several geographical areas representing distinctly different storm `climatologies.' The relative frequency of the two embryo types varies greatly from area to area, in a Way that correlates rather well with average cloud-base temperature. The warmer based clouds produce hail with more frozen drop embryos. The correlation may be explainable either in terms of the dominant precipitation growth process-liquid coalescence or the ice process-or in terms of recycling of embryos, or both. In light of these results, the transferability of any hail suppression technology from one area to another should not be considered to be automatic.

  1. 76 FR 12096 - McCloud-Pit Project; Notice of Availability of the Final Environmental Impact Statement for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-04

    ... Energy Regulatory Commission McCloud-Pit Project; Notice of Availability of the Final Environmental... reviewed the application for license for the McCloud-Pit Hydroelectric Project (FERC No. 2106), located on the McCloud and Pit Rivers in Shasta County, California and has prepared a final environmental...

  2. Aerosol processing through clouds: Results from the European project GCE

    SciTech Connect

    Fuzzi, S.

    1996-12-31

    The atmospheric aerosols affect climate both in a direct and an indirect way, serving as cloud condensation nuclei (CCN). The climate forcing of atmospheric aerosol is opposite in sign to forcing by greenhouse gases. Human activity has changed significantly the global aerosol burden, but also the physical and chemical nature of atmospheric aerosol. Changing chemical properties of the atmospheric aerosol can affect cloud albedo, cloud life-time, and the precipitation regimes. In fact, the ability of aerosol particles to act as CCN depends both on size distribution and on chemical properties of the aerosol population. The fraction of soluble mass in an aerosol particle is a key parameter in determining its hygroscopic behavior and thus its ability to serve as CCN. There are evidences that a relevant fraction of the inactive material is formed by particulate organic compounds. Significant modifications have been shown to occur in an aerosol population passing through a cloud. In particular, sulfate formation due to in-cloud sulphur dioxide oxidation modified the fraction of soluble material carried by the particles which are released in the atmosphere upon cloud evaporation, thus increasing their growth ability for a new cloud cycle.

  3. Global Surface Ultraviolet Radiation Climatology from TOMS and ERBE Data

    NASA Technical Reports Server (NTRS)

    Lubin, Dan

    1998-01-01

    The overall goal of this project has been to develop a method for calculating the distribution of solar ultraviolet radiation (UVR) over most of the earth's surface using NASA's Total Ozone Mapping Spectrometer (TOMS) and Earth Radiation Budget Experiment (ERBE) data, and to use this method to develop a UVR climatology that is useful in the context of the global ozone depletion issue. The research carried out with this support has resulted the following accomplishments: (1) a radioactive transfer method. based on the delta-Eddington approximation, was successfully developed; (2) the method was applied to the five years of overlapping TOMS and ERBE Monthly-Hourly data to examine the impact of global variability in cloud cover on trends in surface UVR; (3) a presentation was made on effects of stratospheric ozone depletion; (4) the radioactive transfer model was finally applied to all daylight hours to make a through study of the global effect of cloud cover;and (6) a five-year global climatology of surface UVR based on all of the research has been prepared for general distribution.

  4. Global Surface Ultraviolet Radiation Climatology from TOMS and ERBE Data

    NASA Technical Reports Server (NTRS)

    Lubin, Dan

    1998-01-01

    The overall goal of this project has been to develop a method for calculating the distribution of solar ultraviolet radiation (UVR) over most of the earth's surface using NASA's Total Ozone Mapping Spectrometer (TOMS) and Earth Radiation Budget Experiment (ERBE) data, and to use this method to develop a UVR climatology that is useful in the context of the global ozone depletion issue. The research carried out with this support has resulted the following accomplishments: (1) a radioactive transfer method. based on the delta-Eddington approximation, was successfully developed; (2) the method was applied to the five years of overlapping TOMS and ERBE Monthly-Hourly data to examine the impact of global variability in cloud cover on trends in surface UVR; (3) a presentation was made on effects of stratospheric ozone depletion; (4) the radioactive transfer model was finally applied to all daylight hours to make a through study of the global effect of cloud cover;and (6) a five-year global climatology of surface UVR based on all of the research has been prepared for general distribution.

  5. The ENSO Effects on Tropical Clouds and Top-of-Atmosphere Cloud Radiative Effects in CMIP5 Models

    NASA Technical Reports Server (NTRS)

    Su, Wenying; Wang, Hailan

    2015-01-01

    The El Nino-Southern Oscillation (ENSO) effects on tropical clouds and top-of-atmosphere (TOA) cloud radiative effects (CREs) in Coupled Model Intercomparison Project Phase5 (CMIP5) models are evaluated using satellite-based observations and International Satellite Cloud Climatology Project satellite simulator output. Climatologically, most CMIP5 models produce considerably less total cloud amount with higher cloud top and notably larger reflectivity than observations in tropical Indo-Pacific (60 degrees East - 200 degrees East; 10 degrees South - 10 degrees North). During ENSO, most CMIP5 models considerably underestimate TOA CRE and cloud changes over western tropical Pacific. Over central tropical Pacific, while the multi-model mean resembles observations in TOA CRE and cloud amount anomalies, it notably overestimates cloud top pressure (CTP) decreases; there are also substantial inter-model variations. The relative effects of changes in cloud properties, temperature and humidity on TOA CRE anomalies during ENSO in the CMIP5 models are assessed using cloud radiative kernels. The CMIP5 models agree with observations in that their TOA shortwave CRE anomalies are primarily contributed by total cloud amount changes, and their TOA longwave CRE anomalies are mostly contributed by changes in both total cloud amount and CTP. The model biases in TOA CRE anomalies particularly the strong underestimations over western tropical Pacific are, however, mainly explained by model biases in CTP and cloud optical thickness (tau) changes. Despite the distinct model cloud biases particularly in tau regime, the TOA CRE anomalies from cloud amount changes are comparable between the CMIP5 models and observations, because of the strong compensations between model underestimation of TOA CRE anomalies from thin clouds and overestimation from medium and thick clouds.

  6. The effect of large-scale model time step and multiscale coupling frequency on cloud climatology, vertical structure, and rainfall extremes in a superparameterized GCM

    DOE PAGES

    Yu, Sungduk; Pritchard, Michael S.

    2015-12-17

    The effect of global climate model (GCM) time step—which also controls how frequently global and embedded cloud resolving scales are coupled—is examined in the Superparameterized Community Atmosphere Model ver 3.0. Systematic bias reductions of time-mean shortwave cloud forcing (~10 W/m2) and longwave cloud forcing (~5 W/m2) occur as scale coupling frequency increases, but with systematically increasing rainfall variance and extremes throughout the tropics. An overarching change in the vertical structure of deep tropical convection, favoring more bottom-heavy deep convection as a global model time step is reduced may help orchestrate these responses. The weak temperature gradient approximation is more faithfullymore » satisfied when a high scale coupling frequency (a short global model time step) is used. These findings are distinct from the global model time step sensitivities of conventionally parameterized GCMs and have implications for understanding emergent behaviors of multiscale deep convective organization in superparameterized GCMs. Lastly, the results may also be useful for helping to tune them.« less

  7. The effect of large-scale model time step and multiscale coupling frequency on cloud climatology, vertical structure, and rainfall extremes in a superparameterized GCM

    SciTech Connect

    Yu, Sungduk; Pritchard, Michael S.

    2015-12-17

    The effect of global climate model (GCM) time step—which also controls how frequently global and embedded cloud resolving scales are coupled—is examined in the Superparameterized Community Atmosphere Model ver 3.0. Systematic bias reductions of time-mean shortwave cloud forcing (~10 W/m2) and longwave cloud forcing (~5 W/m2) occur as scale coupling frequency increases, but with systematically increasing rainfall variance and extremes throughout the tropics. An overarching change in the vertical structure of deep tropical convection, favoring more bottom-heavy deep convection as a global model time step is reduced may help orchestrate these responses. The weak temperature gradient approximation is more faithfully satisfied when a high scale coupling frequency (a short global model time step) is used. These findings are distinct from the global model time step sensitivities of conventionally parameterized GCMs and have implications for understanding emergent behaviors of multiscale deep convective organization in superparameterized GCMs. Lastly, the results may also be useful for helping to tune them.

  8. Observations of marine stratocumulus clouds during FIRE

    NASA Technical Reports Server (NTRS)

    Albrecht, Bruce A.; Randall, David A.; Nicholls, Stephen

    1988-01-01

    The First International Satellite Cloud Climatology Project Regional Experiment (FIRE) to study extensive fields of stratocumulus clouds off the coast of California is presented. Measurements on the regional and detailed local scales were taken, allowing for a wide interpretation of the mean, turbulent, microphysical, radiative, and chemical characteristics of stratocumulus. Multiple aircraft and ground-based remote-sensing systems were used to study the time evolution of the boundary layer structure over a three-week period, and probes from tethered balloons were used to measure turbulence and to collect cloud-microphysical and cloud-radiative data. The observations provide a base for studying the generation maintenance and dissipation of stratocumulus clouds, and could aid in developing numerical models and improved methods for retrieving cloud properties by satellite.

  9. High resolution climate projections to assess the future vulnerability of European urban areas to climatological extreme events

    NASA Astrophysics Data System (ADS)

    Fallmann, Joachim; Wagner, Sven; Emeis, Stefan

    2017-02-01

    Results from high resolution 7-km WRF regional climate model (RCM) simulations are used to analyse changes in the occurrence frequencies of heat waves, of precipitation extremes and of the duration of the winter time freezing period for highly populated urban areas in Central Europe. The projected climate change impact is assessed for 11 urban areas based on climate indices for a future period (2021-2050) compared to a reference period (1971-2000) using the IPCC AR4 A1B Scenario as boundary conditions. These climate indices are calculated from daily maximum, minimum and mean temperatures as well as precipitation amounts. By this, the vulnerability of these areas to future climate conditions is to be investigated. The number of heat waves, as well as the number of single hot days, tropical nights and heavy precipitation events is projected to increase in the near future. In addition, the number of frost days is significantly decreased. Probability density functions of monthly mean summer time temperatures show an increase of the 95th percentile of about 1-3 °C for the future compared with the reference period. The projected increase of cooling and decrease of heating degree days indicate the possible impact on urban energy consumption under future climate conditions.

  10. Interpreting the inter-model spread in regional precipitation projections in the tropics: role of surface evaporation and cloud radiative effects

    NASA Astrophysics Data System (ADS)

    Oueslati, Boutheina; Bony, Sandrine; Risi, Camille; Dufresne, Jean-Louis

    2016-11-01

    In this study, we investigate and quantify different contributors to inter-model differences in regional precipitation projections among CMIP5 climate models. Contributors to the spread are very contrasted between land and ocean. While circulation changes dominate the spread over oceans and continental coasts, thermodynamic changes associated with water vapor increase dominate over inland regions. The inter-model spread in the dynamic component is associated with the change in atmospheric radiative cooling with warming, which largely relates to atmospheric cloud radiative effects. Differences in the thermodynamic component result from the differences in the change in surface evaporation that is explained by decreases in surface humidity and limited surface water availability over land. Secondary contributions to the inter-model spread in thermodynamic and dynamic components result respectively from present-day climatology (owing to the Clausius-Clapeyron scaling) and from the shape of the vertical velocity profile associated with changes in surface temperature gradients. Advancing the physical understanding of the cloud-circulation and precipitation-evaporation couplings and improving their representation in climate models may stand the best chance to reduce uncertainty in regional precipitation projections.

  11. Present-day climatology and projected changes of warm and cold days in the CNRM-CM3 global climate model

    NASA Astrophysics Data System (ADS)

    Ballester, J.; Douville, H.; Chauvin, F.

    2009-01-01

    The impact of global warming on the warmest and coldest days of the annual cycle is explored according to an A2 scenario simulated by the CNRM-CM3 climate model in the framework of the IPCC AR4 intercomparison. Given the multi-model spread in IPCC projections, a validation strategy is proposed using the NCEP/NCAR reanalysis. Validation of the late twentieth century model climatology shows that warm and cold model events are slightly too long and infrequent. Although interannual trends in the warm (cold) day occurrence were positive (negative) only for six (three) of the nine considered sub-continental regions, simulated model trends are always positive (negative). This different behaviour suggests that simulated non-anthropogenic decadal variability is small relative to anthropogenic trends. Large-scale synoptic processes associated with European regional warm and cold peaks are also described and validated. Regional cold peaks are better reproduced than warm peaks, whose intensity accuracy is limited by other physical variables. Positive (negative) winter anomalies of sea and land surface temperature lead to summers with severe (weak) temperatures. These inter-annual anomalies are generated by a persistent pressure dipole over Europe. Regarding climate change, warm (cold) events will become more (less) frequent and longer (shorter). The number of warm days will largely rise and the number of cold days will dramatically decrease. The intensity of warm days will be particularly pronounced over Europe, given the projected summer drying in this region. However, according to the limited skill of the CNRM model, these results must be considered with caution.

  12. 75 FR 48322 - McCloud-Pit Project; Notice of Availability of the Draft Environmental Impact Statement for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-10

    ... Energy Regulatory Commission McCloud-Pit Project; Notice of Availability of the Draft Environmental Impact Statement for the McCloud-Pit Hydroelectric Project and Intention To Hold Public Meetings July 30... CFR part 380 ), the Office of Energy Projects has reviewed the application for license for the...

  13. Decadal cirrus climatology with lidar at midlatitude

    NASA Astrophysics Data System (ADS)

    Hoareau, C.; Keckhut, P.; Baray, J. l.

    2012-04-01

    High-altitude clouds, like cirrus, have been identified as one important regulator of the radiance balance of the earth-atmosphere system (Twomey, 1991), and constitute about 30% of the earth's surface cover (Liou, 1986). Through radiation effects, these clouds are likely to modulate climate system on all scales and are important regulators of the radiative balance of the atmosphere despite their optical depth (Liou et al., 2002). Currently, role of cirrus clouds in the regulation of water vapor as well as the vertical transport of water vapor and ice particles in the vicinity of the tropopause is not perfectly known (Corti et al., 2008). The processes involved are debated (Kiemle et al., 2008) and different formation processes could lead to different cloud characteristics that require to be identified before specific statistical analysis (Keckhut et al., 2006). Lidar measurements provide accurate information on the vertical distribution of cirrus and, therefore, are now used to develop highly resolved cirrus database. A first climatology of cirrus clouds at Midlatitude from lidar measurements has shown cirrus clouds were observed in half of the time (~54%) with subvisible cirrus clouds (SVC) events composing ~23% of the occurrence (Goldfarb et al., 2001). However no distinction according the altitude have been investigated although altitude range and vertical extension of cirrus clouds are critical parameters for the radiative balance of the atmosphere. In a more recent study, a statistical multivariate analysis of one year lidar data acquired in south of France have been realized in order to determine distinct classes of cirrus showing three different classes (Keckhut et al. 2006). Similar results according the classification have been observed in this present study based on a climatology constructed over the period 1996-2007 using a high resolution Rayleigh-Mie-Raman lidar. As the database is long enough, the evolution of cirrus clouds occurrence has also been

  14. Global patterns of cloud optical thickness variation with temperature

    SciTech Connect

    Tselioudis, G.; Rossow, W.B.; Rind, D. )

    1992-12-01

    The International Satellite Cloud Climatology Project (ISCCP) dataset is used to correlate variations of cloud optical thickness and cloud temperature in today's atmosphere. The analysis focuses on low clouds in order to limit the importance of changes in cloud vertical extent, particle size, and water phase. Coherent patterns of change are observed on several time and space scales. On the planetary scale, clouds in colder, higher latitudes are found to be optically thicker than clouds in warmer, lower latitudes. On the seasonal scale, winter clouds are, for the most part, optically thicker than summer clouds. The logarithmic derivative of cloud optical thickness with temperature is used to describe the sign and magnitude of the optical thickness - temperature correlation. The seasonal, latitudinal, and day-to-day variations of this relation are examined for Northern Hemisphere clouds in 1984. The analysis is done separately for clouds over land and ocean. In cold continental clouds, optical thickness increases with temperature, consistent with the temperature variation of the adiabatic cloud water content. In warm continental and in almost all maritime clouds, however, optical thickness decreases with temperature. The behavior of the optical thickness-temperature relation is usually, though not always, the same whether the temperature variations are driven by seasonal, latitudinal, or day-to-day changes. Important exceptions are noted. Some explanations for the observed behavior are proposed. 43 refs., 8 figs.

  15. The effect of clouds on the earth's radiation budget

    NASA Technical Reports Server (NTRS)

    Ziskin, Daniel; Strobel, Darrell F.

    1991-01-01

    The radiative fluxes from the Earth Radiation Budget Experiment (ERBE) and the cloud properties from the International Satellite Cloud Climatology Project (ISCCP) over Indonesia for the months of June and July of 1985 and 1986 were analyzed to determine the cloud sensitivity coefficients. The method involved a linear least squares regression between co-incident flux and cloud coverage measurements. The calculated slope is identified as the cloud sensitivity. It was found that the correlations between the total cloud fraction and radiation parameters were modest. However, correlations between cloud fraction and IR flux were improved by separating clouds by height. Likewise, correlations between the visible flux and cloud fractions were improved by distinguishing clouds based on optical depth. Calculating correlations between the net fluxes and either height or optical depth segregated cloud fractions were somewhat improved. When clouds were classified in terms of their height and optical depth, correlations among all the radiation components were improved. Mean cloud sensitivities based on the regression of radiative fluxes against height and optical depth separated cloud types are presented. Results are compared to a one-dimensional radiation model with a simple cloud parameterization scheme.

  16. The OCareCloudS project: Toward organizing care through trusted cloud services.

    PubMed

    De Backere, Femke; Ongenae, Femke; Vannieuwenborg, Frederic; Van Ooteghem, Jan; Duysburgh, Pieter; Jansen, Arne; Hoebeke, Jeroen; Wuyts, Kim; Rossey, Jen; Van den Abeele, Floris; Willems, Karen; Decancq, Jasmien; Annema, Jan Henk; Sulmon, Nicky; Van Landuyt, Dimitri; Verstichel, Stijn; Crombez, Pieter; Ackaert, Ann; De Grooff, Dirk; Jacobs, An; De Turck, Filip

    2016-01-01

    The increasing elderly population and the shift from acute to chronic illness makes it difficult to care for people in hospitals and rest homes. Moreover, elderly people, if given a choice, want to stay at home as long as possible. In this article, the methodologies to develop a cloud-based semantic system, offering valuable information and knowledge-based services, are presented. The information and services are related to the different personal living hemispheres of the patient, namely the daily care-related needs, the social needs and the daily life assistance. Ontologies are used to facilitate the integration, analysis, aggregation and efficient use of all the available data in the cloud. By using an interdisciplinary research approach, where user researchers, (ontology) engineers, researchers and domain stakeholders are at the forefront, a platform can be developed of great added value for the patients that want to grow old in their own home and for their caregivers.

  17. Cloud cover estimation using bispectral satellite measurements

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.; Childs, J.; Dorian, P.

    1986-01-01

    An algorithm has been developed for cloud cover estimation using bispectral satellite measurements. Based on the distribution of pixels in albedo-brightness temperature space, a number of threshold values are applied to identify those pixels which are most likely totally cloud filled. Mean cloudy-column albedo in a region much larger than a single pixel is then estimated and cloud cover computed. The algorithm has been applied to the International Satellite Cloud Climatology Project Geostationary Meteorological Satellite B2 data. Locations of tropical convective cells and the passage of fronts in higher latitudes are identified. Since these features represent the states of large-scale atmospheric circulations, it is concluded that the algorithm can yield consistent cloud data sets useful for climate studies.

  18. Constructing an AIRS Climatology for Data Visualization and Analysis to Serve the Climate Science and Application Communities

    NASA Technical Reports Server (NTRS)

    Ding, Feng; Keim, Elaine; Hearty, Thomas J.; Wei, Jennifer; Savtchenko, Andrey; Theobald, Michael; Vollmer, Bruce

    2016-01-01

    The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is the home of processing, archiving, and distribution services for NASA sounders: the present Aqua AIRS mission and the succeeding SNPP CrIS mission. The AIRS mission is entering its 15th year of global observations of the atmospheric state, including temperature and humidity profiles, outgoing longwave radiation, cloud properties, and trace gases. The GES DISC, in collaboration with the AIRS Project, released product from the version 6 algorithm in early 2013. Giovanni, a Web-based application developed by the GES DISC, provides a simple and intuitive way to visualize, analyze, and access vast amounts of Earth science remote sensing data without having to download the data. Most important variables from version 6 AIRS product are available in Giovanni. We are developing a climatology product using 14-year AIRS retrievals. The study can be a good start for the long term climatology from NASA sounders: the AIRS and the succeeding CrIS. This presentation will show the impacts to the climatology product from different aggregation methods. The climatology can serve climate science and application communities in data visualization and analysis, which will be demonstrated using a variety of functions in version 4 Giovanni. The highlights of these functions include user-defined monthly and seasonal climatology, inter annual seasonal time series, anomaly analysis.

  19. Comparative climatology - Mars and earth

    NASA Technical Reports Server (NTRS)

    Haberle, R. M.

    1985-01-01

    Spacecraft missions to Mars during the 1960's and 1970's gave a remarkably detailed picture of the meteorological and climatological conditions that characterize its atmosphere. During the relatively brief history of close-up exploration of Mars, much of the ambiguity associated with the early telescopic observations has been resolved, and a new image of the red planet has emerged. Accurate measurements taken both from orbit and the surface reveal a cool, thin atmosphere that condenses, transports water, and generates clouds and dust storms, and that has a global-scale wind system not unlike the one known on earth. This paper highlights the current view of the Martian climate system and what controls it. For perspective, comparisons with earth's climate system are included where appropriate.

  20. Comparative Climatology of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Mackwell, Stephen J.; Simon-Miller, Amy A.; Harder, Jerald W.; Bullock, Mark A.

    stimulate further research on this critical subject. The study of climate involves much more than understanding atmospheric processes. This subtlety is particularly appreciated for Earth, where chemical cycles, geology, ocean influences, and biology are considered in most climate models. In Part IV, Surface and Interior, we look at the role that geochemical cycles, volcanism, and interior mantle processes play in the stability and evolution of terrestrial planetary climates. There is one vital commonality between the climates of all the planets of the solar system: Regardless of the different processes that dominate each of the climates of Earth, Mars, Venus, and Titan, they are all ultimately forced by radiation from the same star, albeit at variable distances. In Part V, Solar Influences, we discuss how the Sun's early evolution affected the climates of the terrestrial planets, and how it continues to control the temperatures and compositions of planetary atmospheres. This will be of particular interest as models of exoplanets, and the influences of much different stellar types and distances, are advanced by further observations. Comparisons of atmospheric and climate processes between the planets in our solar system has been a focus of numerous conferences over the past decade, including the Exoclimes conference series. In particular, this book project was closely tied to a conference on Comparative Climatology of Terrestrial Planets that was held in Boulder, Colorado, on June 25-28, 2012. This book benefited from the opportunity for the author teams to interact and obtain feedback from the broader community, but the chapters do not in general tie directly to presentations at the conference. The conference, which was organized by a diverse group of atmospheric and climate scientists led by Mark Bullock and Lori Glaze, sought to build connections between the various communities, focusing on synergies and complementary capabilities. Discussion panels at the end of most

  1. An improved enhancement layer for octree based point cloud compression with plane projection approximation

    NASA Astrophysics Data System (ADS)

    Ainala, Khartik; Mekuria, Rufael N.; Khathariya, Birendra; Li, Zhu; Wang, Ye-Kui; Joshi, Rajan

    2016-09-01

    Recent advances in point cloud capture and applications in VR/AR sparked new interests in the point cloud data compression. Point Clouds are often organized and compressed with octree based structures. The octree subdivision sequence is often serialized in a sequence of bytes that are subsequently entropy encoded using range coding, arithmetic coding or other methods. Such octree based algorithms are efficient only up to a certain level of detail as they have an exponential run-time in the number of subdivision levels. In addition, the compression efficiency diminishes when the number of subdivision levels increases. Therefore, in this work we present an alternative enhancement layer to the coarse octree coded point cloud. In this case, the base layer of the point cloud is coded in known octree based fashion, but the higher level of details are coded in a different way in an enhancement layer bit-stream. The enhancement layer coding method takes the distribution of the points into account and projects points to geometric primitives, i.e. planes. It then stores residuals and applies entropy encoding with a learning based technique. The plane projection method is used for both geometry compression and color attribute compression. For color coding the method is used to enable efficient raster scanning of the color attributes on the plane to map them to an image grid. Results show that both improved compression performance and faster run-times are achieved for geometry and color attribute compression in point clouds.

  2. The NEWS Water Cycle Climatology

    NASA Technical Reports Server (NTRS)

    Rodell, Matthew; Beaudoing, Hiroko Kato; L'Ecuyer, Tristan; William, Olson

    2012-01-01

    NASA's Energy and Water Cycle Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy cycle consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the first phase of the NEWS Water and Energy Cycle Climatology project was to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. The project was a multi-institutional collaboration with more than 20 active contributors. This presentation will describe the results of the water cycle component of the first phase of the project, which include seasonal (monthly) climatologies of water fluxes over land, ocean, and atmosphere at continental and ocean basin scales. The requirement of closure of the water budget (i.e., mass conservation) at various scales was exploited to constrain the flux estimates via an optimization approach that will also be described. Further, error assessments were included with the input datasets, and we examine these in relation to inferred uncertainty in the optimized flux estimates in order to gauge our current ability to close the water budget within an expected uncertainty range.

  3. Global patterns of cloud optical thickness variation with temperature

    NASA Technical Reports Server (NTRS)

    Tselioudis, George; Rossow, William B.; Rind, David

    1992-01-01

    The International Satellite Cloud Climatology Project dataset is used to correlate variations of cloud optical thickness and cloud temperature in today's atmosphere. The analysis focuses on low clouds in order to limit the importance of changes in cloud vertical extent, particle size, and water phase. Coherent patterns of change are observed on several time and space scales. On the planetary scale, clouds in colder, higher latitudes are found to be optically thicker than clouds in warmer, lower latitudes. On the seasonal scale, winter clouds are, for the most part, optically thicker than summer clouds. The logarithmic derivative of cloud optical thickness with temperature is used to describe the sign and magnitude of the optical thickness-temperature correlation. The seasonal, latitudinal, and day-to-day variations of this relation are examined for Northern Hemisphere clouds in 1984. In cold continental clouds, optical thickness increases with temperature, consistent with the temperature variation of the adiabatic cloud water content. In warm continental and in almost all maritime clouds, however, optical thickness decreases with temperature.

  4. All Sky Cloud Coverage Monitoring for SONG-China Project

    NASA Astrophysics Data System (ADS)

    Tian, J. F.; Deng, L. C.; Yan, Z. Z.; Wang, K.; Wu, Y.

    2016-05-01

    In order to monitor the cloud distributions at Qinghai station, a site selected for SONG (Stellar Observations Network Group)-China node, the design of the proto-type of all sky camera (ASC) applied in Xinglong station is adopted. Both hardware and software improvements have been made in order to be more precise and deliver quantitative measurements. The ARM (Advanced Reduced Instruction Set Computer Machine) MCU (Microcontroller Unit) instead of PC is used to control the upgraded version of ASC. A much higher reliability has been realized in the current scheme. Independent of the positions of the Sun and Moon, the weather conditions are constantly changing, therefore it is difficult to get proper exposure parameters using only the temporal information of the major light sources. A realistic exposure parameters for the ASC can actually be defined using a real-time sky brightness monitor that is also installed at the same site. The night sky brightness value is a very sensitive function of the cloud coverage, and can be accurately measured by the sky quality monitor. We study the correlation between the exposure parameter and night sky brightness value, and give the mathematical relation. The images of the all sky camera are inserted into database directly. All sky quality images are archived in FITS format which can be used for further analysis.

  5. Study of Mechanisms of Aerosol Indirect Effects on Glaciated Clouds: Progress during the Project Final Technical Report

    SciTech Connect

    Phillips, Vaughan T. J.

    2013-10-18

    This 3-year project has studied how aerosol pollution influences glaciated clouds. The tool applied has been an 'aerosol-cloud model'. It is a type of Cloud-System Resolving Model (CSRM) modified to include 2-moment bulk microphysics and 7 aerosol species, as described by Phillips et al. (2009, 2013). The study has been done by, first, improving the model and then performing sensitivity studies with validated simulations of a couple of observed cases from ARM. These are namely the Tropical Warm Pool International Cloud Experiment (TWP-ICE) over the tropical west Pacific and the Cloud and Land Surface Interaction Campaign (CLASIC) over Oklahoma. During the project, sensitivity tests with the model showed that in continental clouds, extra liquid aerosols (soluble aerosol material) from pollution inhibited warm rain processes for precipitation production. This promoted homogeneous freezing of cloud droplets and aerosols. Mass and number concentrations of cloud-ice particles were boosted. The mean sizes of cloud-ice particles were reduced by the pollution. Hence, the lifetime of glaciated clouds, especially ice-only clouds, was augmented due to inhibition of sedimentation and ice-ice aggregation. Latent heat released from extra homogeneous freezing invigorated convective updrafts, and raised their maximum cloud-tops, when aerosol pollution was included. In the particular cases simulated in the project, the aerosol indirect effect of glaciated clouds was twice than of (warm) water clouds. This was because glaciated clouds are higher in the troposphere than water clouds and have the first interaction with incoming solar radiation. Ice-only clouds caused solar cooling by becoming more extensive as a result of aerosol pollution. This 'lifetime indirect effect' of ice-only clouds was due to higher numbers of homogeneously nucleated ice crystals causing a reduction in their mean size, slowing the ice-crystal process of snow production and slowing sedimentation. In addition

  6. Using Roving Cloud Observations from the S'COOL Project to Engage Citizen Scientists

    NASA Astrophysics Data System (ADS)

    Lewis, P. M.; Oostra, D.; Moore, S. W.; Rogerson, T. M.; Crecelius, S. A.; Chambers, L. H.

    2011-12-01

    Students' Clouds Observations On-Line (S'COOL) is a hands-on project, which supports NASA research on the Earth's climate. Through their observations, participants are engaged in identifying cloud-types and levels and sending that information to NASA. The two main groups of S'COOL observers are permanent locations such as regularly participating classrooms, and non-permanent locations or Rovers. These non-permanent locations can be a field trip, vacation, or just an occasional observation from a backyard. S'COOL welcomes participation from any interested observers, especially from places where official weather observations are few and far between. This program is offered to citizen scientists all over the world. They are participating in climate research by reporting cloud types and levels within +/- 15 minutes of a satellite overpass and sending that information back to NASA. When a participant's cloud observation coincides with a satellite overpass, the project sends them an email with a MODIS image of the overpass location, and a comparison of the satellite's cloud data results next to their ground-based report. This allows for the students and citizen scientists to participate in ground-truthing the CERES satellite data, to determine the level of agreement/disagreement. A new tool slated for future use in cloud identification, developed by the S'COOL team, is a mobile application. The application is entitled "Cloud Identification for Students" or "CITRUS". The mobile application utilizes a cloud dichotomous key with images to help with cloud identification. Also included in the application is a link to the project's cloud-reporting page to help with data submission in the field. One of the project's recent and most unique roving observers is a solo ocean rower who has traversed many of the world's ocean basins alone in a rowboat. While rowing across the oceans, she has recently been making cloud observations, which she sends back to us for analysis. In doing so

  7. Projects in Computer Aided Climatology.

    DTIC Science & Technology

    1981-07-01

    Always blank 17 Cbservation herder column (blank or 9) if ŝ" the scope is clear Always blank 19 Azimuth angle 1 header (blank or 9) if ŝ" there are no...optional. SUBSECTION I-A THE EQUATIONS OF TRANSFORMATION The mapping procedure used was originally proposed by the Swiss mathematician, Johann Heinrich

  8. Interpreting measurements obtained with the cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The software developed for the analysis of data from the Cloud Absorption Radiometer (CAR) is discussed. The CAR is a multichannel radiometer designed to measure the radiation field in the middle of an optically thick cloud (the diffusion domain). It can also measure the surface albedo and escape function. The instrument currently flies on a C-131A aircraft operated by the University of Washington. Most of this data was collected during the First International satellite cloud climatology project Regional Experiment (FIRE) Marine Stratocumulus Intensive Field Observation program off San Diego during July 1987. Earlier flights of the CAR have also been studied.

  9. A systematic risk management approach employed on the CloudSat project

    NASA Technical Reports Server (NTRS)

    Basilio, R. R.; Plourde, K. S.; Lam, T.

    2000-01-01

    The CloudSat Project has developed a simplified approach for fault tree analysis and probabilistic risk assessment. A system-level fault tree has been constructed to identify credible fault scenarios and failure modes leading up to a potential failure to meet the nominal mission success criteria.

  10. A systematic risk management approach employed on the CloudSat project

    NASA Technical Reports Server (NTRS)

    Basilio, R. R.; Plourde, K. S.; Lam, T.

    2000-01-01

    The CloudSat Project has developed a simplified approach for fault tree analysis and probabilistic risk assessment. A system-level fault tree has been constructed to identify credible fault scenarios and failure modes leading up to a potential failure to meet the nominal mission success criteria.

  11. Shallowness of tropical low clouds as a predictor of climate models' response to warming

    NASA Astrophysics Data System (ADS)

    Brient, Florent; Schneider, Tapio; Tan, Zhihong; Bony, Sandrine; Qu, Xin; Hall, Alex

    2016-07-01

    How tropical low clouds change with climate remains the dominant source of uncertainty in global warming projections. An analysis of an ensemble of CMIP5 climate models reveals that a significant part of the spread in the models' climate sensitivity can be accounted by differences in the climatological shallowness of tropical low clouds in weak-subsidence regimes: models with shallower low clouds in weak-subsidence regimes tend to have a higher climate sensitivity than models with deeper low clouds. The dynamical mechanisms responsible for the model differences are analyzed. Competing effects of parameterized boundary-layer turbulence and shallow convection are found to be essential. Boundary-layer turbulence and shallow convection are typically represented by distinct parameterization schemes in current models—parameterization schemes that often produce opposing effects on low clouds. Convective drying of the boundary layer tends to deepen low clouds and reduce the cloud fraction at the lowest levels; turbulent moistening tends to make low clouds more shallow but affects the low-cloud fraction less. The relative importance different models assign to these opposing mechanisms contributes to the spread of the climatological shallowness of low clouds and thus to the spread of low-cloud changes under global warming.

  12. Investigating a solar influence on cloud cover using the North American Regional Reanalysis data

    NASA Astrophysics Data System (ADS)

    Krahenbuhl, Daniel Scott

    2015-06-01

    The controversial connection between cosmic rays, solar activity, and cloud cover is investigated using a climatological reconstructed reanalysis product: the North American Regional Reanalysis which provides high-resolution, low, mid-level, high, and total cloud cover data over a Lambert conformal conic projection permitting land/ocean discrimination. Pearson's product-moment regional correlations were obtained between monthly cloud cover data and solar variability indicators, cosmic ray neutron monitors, several climatological indices, including the Atlantic Multidecadal Oscillation (AMO), and between cloud layers. Regions of the mid-latitude oceans exhibited a positive correlation with cosmic ray flux. Additionally, this maritime low cloud cover exhibits the only failed correlation significance with other altitudes. The cross correlation reveals that cloud cover is positively correlated everywhere but for ocean low cloud cover, supporting the unique response of the marine layer. The results of this investigation suggest that with the assumption that solar forcing does impact cloud cover, measurements of solar activity exhibits a slightly higher correlation than GCRs. The only instance where GCRs exhibit a positive regional correlation with cloud cover is for maritime low clouds. The AMO exerts the greatest control of cloud cover in the NARR domain.

  13. Evidence for liquid-phase cirrus cloud formation from volcanic aerosols: climatic implications.

    PubMed

    Sassen, K

    1992-07-24

    Supercooled droplets in cirrus uncinus cell heads between -40 degrees and -50 degrees C are identified from Project FIRE [First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment] polarization lidar measurements. Although short-lived, complexes of these small liquid cells seem to have contributed importantly to the formation of the cirrus. Freezing-point depression effects in solution droplets, apparently resulting from relatively large cloud condensation nuclei of volcanic origin, can be used to explain this rare phenomenon. An unrecognized volcano-cirrus cloud climate feedback mechanism is implied by these findings.

  14. ISCCP Cloud Properties Associated with Standard Cloud Types Identified in Individual Surface Observations

    NASA Technical Reports Server (NTRS)

    Hahn, Carole J.; Rossow, William B.; Warren, Stephen G.

    1999-01-01

    Individual surface weather observations from land stations and ships are compared with individual cloud retrievals of the International Satellite Cloud Climatology Project (ISCCP), Stage C1, for an 8-year period (1983-1991) to relate cloud optical thicknesses and cloud-top pressures obtained from satellite data to the standard cloud types reported in visual observations from the surface. Each surface report is matched to the corresponding ISCCP-C1 report for the time of observation for the 280x280-km grid-box containing that observation. Classes of the surface reports are identified in which a particular cloud type was reported present, either alone or in combination with other clouds. For each class, cloud amounts from both surface and C1 data, base heights from surface data, and the frequency-distributions of cloud-top pressure (p(sub c) and optical thickness (tau) from C1 data are averaged over 15-degree latitude zones, for land and ocean separately, for 3-month seasons. The frequency distribution of p(sub c) and tau is plotted for each of the surface-defined cloud types occurring both alone and with other clouds. The average cloud-top pressures within a grid-box do not always correspond well with values expected for a reported cloud type, particularly for the higher clouds Ci, Ac, and Cb. In many cases this is because the satellites also detect clouds within the grid-box that are outside the field of view of the surface observer. The highest average cloud tops are found for the most extensive cloud type, Ns, averaging 7 km globally and reaching 9 km in the ITCZ. Ns also has the greatest average retrieved optical thickness, tau approximately equal 20. Cumulonimbus clouds may actually attain far greater heights and depths, but do not fill the grid-box. The tau-p(sub c) distributions show features that distinguish the high, middle, and low clouds reported by the surface observers. However, the distribution patterns for the individual low cloud types (Cu, Sc, St

  15. Operation Hardtack. Project 6. 6. X-band radar determination of nuclear-cloud parameters

    SciTech Connect

    Bastian, C.W.; Robbiani, R.; Hargrave, J.

    1985-09-01

    The general objectives of this project were to make observations with weather Radar Set AN/CPS-9 in order to determine what characteristics and parameters of a nuclear detonation could be detected with X-band radar. The specific objectives were to obtain data that would lead to the determination of the following information relative to the nuclear cloud; rate of rise, rate of horizontal growth, maximum height, maximum diameter, stabilized height, fallout pattern due to the initial cloud formation, and range and azimuth versus time. As a result of this project, it was determined that the AN/CPS-9 radar is well suited for observations of surface or near-surface bursts, as would be expected from a comparison of its performance characteristics with those of other available radar sets.

  16. Derivation of Tropospheric Ozone Climatology and Trends from TOMS Data

    NASA Technical Reports Server (NTRS)

    Newchurch, Michael J.; McPeters, Rich; Logan, Jennifer; Kim, Jae-Hwan

    2002-01-01

    This research addresses the following three objectives: (1) Derive tropospheric ozone columns from the TOMS instruments by computing the difference between total-ozone columns over cloudy areas and over clear areas in the tropics; (2) Compute secular trends in Nimbus-7 derived tropospheric Ozone column amounts and associated potential trends in the decadal-scale tropical cloud climatology; (3) Explain the occurrence of anomalously high ozone retrievals over high ice clouds.

  17. Antarctic Meteorology and Climatology

    NASA Astrophysics Data System (ADS)

    King, J. C.; Turner, J.

    1997-07-01

    This book is a comprehensive survey of the climatology and meteorology of Antarctica. The first section of the book reviews the methods by which we can observe the Antarctic atmosphere and presents a synthesis of climatological measurements. In the second section, the authors consider the processes that maintain the observed climate, from large-scale atmospheric circulation to small-scale processes. The final section reviews our current knowledge of the variability of Antarctic climate and the possible effects of "greenhouse" warming. The authors stress links among the Antarctic atmosphere, other elements of the Antarctic climate system (oceans, sea ice and ice sheets), and the global climate system. This volume will be of greatest interest to meteorologists and climatologists with a specialized interest in Antarctica, but it will also appeal to researchers in Antarctic glaciology, oceanography and biology. Graduates and undergraduates studying physical geography, and the earth, atmospheric and environmental sciences will find much useful background material in the book.

  18. A comparison of cirrus clouds determined by ISCCP and SAGE-II and their relation to convection in the tropics

    NASA Technical Reports Server (NTRS)

    Christopher, Sundar A.; Vonder Haar, Thomas H.

    1992-01-01

    Results of tropical thin cirrus cloud retrievals using International Satellite Cloud Climatology Project (ISCCP) and Stratospheric Aerosol and Gaseous Experiment (SAGE-II) data from January 1985 are presented. A preliminary analysis of the results shows that thin cirrus increases with increasing height in both data sets, and SAGE-II exhibits a high frequency of occurrence. The thin cirrus extinction coefficient shows maxima around the convective regions of South America and the western Pacific Ocean.

  19. The FIRE Project

    NASA Technical Reports Server (NTRS)

    Mcdougal, D.

    1986-01-01

    The International Satellite Cloud Climatology Project's (ISCCP) First ISCCP Regional Experiment (FIRE) project is a program to validate the cloud parameters derived by the ISCCP. The 4- to 5-year program will concentrate on clouds in the continental United States, particularly cirrus and marine stratocumulus clouds. As part of the validation process, FIRE will acquire satellite, aircraft, balloon, and surface data. These data (except for the satellite data) will be amalgamated into one common data set. Plans are to generate a standardized format structure for use in the PCDS. Data collection will begin in April 1986, but will not be available to the general scientific community until 1987 or 1988. Additional pertinent data sets already reside in the PCDS. Other qualifications of the PCDS for use in this validation program were enumerated.

  20. Ground-Based Cloud and Atmospheric Boundary Layer Observations for the Project: High Definition Clouds and Precipitation for Advancing Climate Prediction, HD(CP)2

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; Ebell, K.; Ulrich, U.; Schween, J. H.; Bohn, B.; Görsdorf, U.; Leinweber, R.; Päschke, E.; Baars, H.; Seifert, P.; Klein Baltink, H.

    2014-12-01

    The German research initiative ''High Definition Clouds and Precipitation for advancing Climate Prediction, HD(CP)2'' aims for an improved representation of clouds and precipitation in climate models. Model development and its evaluation require comprehensive observational datasets. A specific work package was established to create uniform and documented observational datasets for the HD(CP)2 data base. Datasets included ground-based remote-sensing (Doppler lidars, ceilometers, microwave radiometers, and cloud radars) and in-situ (meteorological and radiation sensors) measurements. Four supersites (Jülich ObservatorY for Cloud Evolution (JOYCE), Lindenberg Meteorological Observatory - Richard Assmann Observatory (RAO), and Leipzig Aerosol and Cloud Remote Observations System (LACROS) in Germany, and Cabauw experimental site for atmospheric research (Cesar) in the Netherlands) are finalizing the operational procedures to provide quality controlled (and calibrated if possible) remote-sensing and in-situ observations, retrievals on atmospheric boundary layer state (e.g. winds, mixing layer height, humidity and temperature), and cloud macro and micro physical properties with uncertainty estimations or at least quality flags. During the project new processing and retrieval methods were developed if no commonly agreed or satisfying methods were available. Especially, large progress was made concerning uncertainty estimation and automated quality control. Additionally, the data from JOYCE are used in a radiative closure studies under cloudy conditions to evaluate retrievals of cloud properties. The current status of work progress will be presented.

  1. Near-global survey of effective droplet radii in liquid water clouds using ISCCP data

    NASA Technical Reports Server (NTRS)

    Han, Qingyan; Rossow, William B.; Lacis, Andrew B.

    1994-01-01

    A global survey of cloud particle size variations can provide crucial constraints on how cloud processes determine cloud liquid water contents and their variation with temperature, and further, may indicate the magnitude of aerosol effects on clouds. A method, based on a complete radiative transfer model for Advanced Very High Resolution Radiometer (AVHRR)-measured radiances, is described for retrieving cloud particle radii in liquid water clouds from satellite data currently available from the International Satellite Cloud Climatology Project. Results of sensitivity tests and validation studies provide error estimates. AVHRR data from NOAA-9 and NOAA-10 have been analyzed for January, April, July and October in 1987 and 1988. The results of this first survey reveal systematic continental and maritime differences and hemispheric contrasts that are indicative of the effects of associated aerosol concentration differences: cloud droplet radii in continental water clouds are about 2-3 micrometers smaller than in marine clouds, and droplet radii are about 1 micrometer smaller in marine clouds of the Northern Hemisphere than in the Southern Hemisphere. The height dependencies of cloud droplet radii in continental and marine clouds are also consistent with differences in the vertical profiles of aerosol concentration. Significant seasonal and diurnal variations of effective droplet radii are also observed, particularly at lower latitudes. Variations of the relationship between cloud optical thickness and droplet radii may indicate variations in cloud microphysical regimes.

  2. Analysis of the Diurnal Cycle of Precipitation and its Relation to Cloud Radiative Forcing Using TRMM Products

    NASA Technical Reports Server (NTRS)

    Randall, David A.; Fowler, Laura D.; Lin, Xin

    1998-01-01

    In order to improve our understanding of the interactions between clouds, radiation, and the hydrological cycle simulated in the Colorado State University General Circulation Model (CSU GCM), we focused our research on the analysis of the diurnal cycle of precipitation, top-of-the-atmosphere and surface radiation budgets, and cloudiness using 10-year long Atmospheric Model Intercomparison Project (AMIP) simulations. Comparisons the simulated diurnal cycle were made against the diurnal cycle of Earth Radiation Budget Experiment (ERBE) radiation budget and International Satellite Cloud Climatology Project (ISCCP) cloud products. This report summarizes our major findings over the Amazon Basin.

  3. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Key, J.

    1989-01-01

    The objectives are to develop a suitable validation data set for evaluating the effectiveness of the International Satellite Cloud Climatology Project (ISCCP) algorithm for cloud retrieval in polar regions, to identify limitations of current procedures and to explore potential means to remedy them using textural classifiers, and to compare synoptic cloud data from model runs with observations. Toward the first goal, a polar data set consisting of visible, thermal, and passive microwave data was developed. The AVHRR and SMMR data were digitally merged to a polar stereographic projection with an effective pixel size of 5 sq km. With this data set, two unconventional methods of classifying the imagery for the analysis of polar clouds and surfaces were examined: one based on fuzzy sets theory and another based on a trained neural network. An algorithm for cloud detection was developed from an early test version of the ISCCP algorithm. This algorithm includes the identification of surface types with passive microwave, then temporal tests at each pixel location in the cloud detection phase. Cloud maps and clear sky radiance composites for 5 day periods are produced. Algorithm testing and validation was done with both actural AVHRR/SMMR data, and simulated imagery. From this point in the algorithm, groups of cloud pixels are examined for their spectral and textural characteristics, and a procedure is developed for the analysis of cloud patterns utilizing albedo, IR temperature, and texture. In a completion of earlier work, empirical analyses of arctic cloud cover were explored through manual interpretations of DMSP imagery and compared to U.S. Air Force 3D-nephanalysis. Comparisons of observed cloudiness from existing climatologies to patterns computed by the GISS climate model were also made.

  4. Comparison between SAGE II and ISCCP high-level clouds. 1: Global and zonal mean cloud amounts

    NASA Technical Reports Server (NTRS)

    Liao, Xiaohan; Rossow, William B.; Rind, David

    1995-01-01

    Global high-level clouds identified in Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements for January and July in the period 1985 to 1990 are compared with near-nadir-looking observations from the International Satellite Cloud Climatology Project (ISCCP). Global and zonal mean high-level cloud amounts from the two data sets agree very well, if clouds with layer extinction coefficients of less than 0.008/km at 1.02 micrometers wavelength are removed from the SAGE II results and all detected clouds are interpreted to have an average horizontal size of about 75 km along the 200 km transimission path length of the SAGE II observations. The SAGE II results are much more sensitive to variations of assumed cloud size than to variations of detection threshold. The geographical distribution of cloud fractions shows good agreement, but systematic regional differences also indicate that the average cloud size varies somewhat among different climate regimes. The more sensitive SAGE II results show that about one third of all high-level clouds are missed by ISCCP but that these clouds have very low optical thicknesses (less than 0.1 at 0.6 micrometers wavelength). SAGE II sampling error in monthly zonal cloud fraction is shown to produce no bias, to be less than the intraseasonal natural variability, but to be comparable with the natural variability at longer time scales.

  5. Comparison between SAGE II and ISCCP high-level clouds. 1: Global and zonal mean cloud amounts

    NASA Technical Reports Server (NTRS)

    Liao, Xiaohan; Rossow, William B.; Rind, David

    1995-01-01

    Global high-level clouds identified in Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements for January and July in the period 1985 to 1990 are compared with near-nadir-looking observations from the International Satellite Cloud Climatology Project (ISCCP). Global and zonal mean high-level cloud amounts from the two data sets agree very well, if clouds with layer extinction coefficients of less than 0.008/km at 1.02 micrometers wavelength are removed from the SAGE II results and all detected clouds are interpreted to have an average horizontal size of about 75 km along the 200 km transimission path length of the SAGE II observations. The SAGE II results are much more sensitive to variations of assumed cloud size than to variations of detection threshold. The geographical distribution of cloud fractions shows good agreement, but systematic regional differences also indicate that the average cloud size varies somewhat among different climate regimes. The more sensitive SAGE II results show that about one third of all high-level clouds are missed by ISCCP but that these clouds have very low optical thicknesses (less than 0.1 at 0.6 micrometers wavelength). SAGE II sampling error in monthly zonal cloud fraction is shown to produce no bias, to be less than the intraseasonal natural variability, but to be comparable with the natural variability at longer time scales.

  6. Cloud microphysical relationships and their implication on entrainment and mixing mechanism for the stratocumulus clouds measured during the VOCALS project

    DOE PAGES

    Yum, Seong Soo; Wang, Jian; Liu, Yangang; ...

    2015-05-27

    Cloud microphysical data obtained from G-1 aircraft flights over the southeastern pacific during the VOCALS-Rex field campaign were analyzed for evidence of entrainment mixing of dry air from above cloud top. Mixing diagram analysis was made for the horizontal flight data recorded at 1 Hz and 40 Hz. The dominant observed feature, a positive relationship between cloud droplet mean volume (V) and liquid water content (L), suggested occurrence of homogeneous mixing. On the other hand, estimation of the relevant scale parameters (i.e., transition length scale and transition scale number) consistently indicated inhomogeneous mixing. Importantly, the flight altitudes of the measurementsmore » were significantly below cloud top. We speculate that mixing of the entrained air near the cloud top may have indeed been inhomogeneous; but due to vertical circulation mixing, the correlation between V and L became positive at the measurement altitudes in mid-level of clouds, because during their descent, cloud droplets evaporate, faster in more diluted cloud parcels, leading to a positive correlation between V and L regardless of the mixing mechanism near the cloud top.« less

  7. Cloud microphysical relationships and their implication on entrainment and mixing mechanism for the stratocumulus clouds measured during the VOCALS project

    SciTech Connect

    Yum, Seong Soo; Wang, Jian; Liu, Yangang; Senum, Gunnar; Springston, Stephen; McGraw, Robert; Yeom, Jae Min

    2015-05-27

    Cloud microphysical data obtained from G-1 aircraft flights over the southeastern pacific during the VOCALS-Rex field campaign were analyzed for evidence of entrainment mixing of dry air from above cloud top. Mixing diagram analysis was made for the horizontal flight data recorded at 1 Hz and 40 Hz. The dominant observed feature, a positive relationship between cloud droplet mean volume (V) and liquid water content (L), suggested occurrence of homogeneous mixing. On the other hand, estimation of the relevant scale parameters (i.e., transition length scale and transition scale number) consistently indicated inhomogeneous mixing. Importantly, the flight altitudes of the measurements were significantly below cloud top. We speculate that mixing of the entrained air near the cloud top may have indeed been inhomogeneous; but due to vertical circulation mixing, the correlation between V and L became positive at the measurement altitudes in mid-level of clouds, because during their descent, cloud droplets evaporate, faster in more diluted cloud parcels, leading to a positive correlation between V and L regardless of the mixing mechanism near the cloud top.

  8. Eclipsing binary stars in the Large and Small Magellanic Clouds from the MACHO project: The Sample

    SciTech Connect

    Faccioli, L; Alcock, C; Cook, K; Prochter, G; Protopapas, P; Syphers, D

    2007-03-29

    We present a new sample of 4634 eclipsing binary stars in the Large Magellanic Cloud (LMC), expanding on a previous sample of 611 objects and a new sample of 1509 eclipsing binary stars in the Small Magellanic Cloud (SMC), that were identified in the light curve database of the MACHO project. We perform a cross correlation with the OGLE-II LMC sample, finding 1236 matches. A cross correlation with the OGLE-II SMC sample finds 698 matches. We then compare the LMC subsamples corresponding to center and the periphery of the LMC and find only minor differences between the two populations. These samples are sufficiently large and complete that statistical studies of the binary star populations are possible.

  9. Polar cloud observatory at Ny-Ålesund in GRENE Arctic Climate Change Research Project

    NASA Astrophysics Data System (ADS)

    Yamanouchi, Takashi; Takano, Toshiaki; Shiobara, Masataka; Okamoto, Hajime; Koike, Makoto; Ukita, Jinro

    2016-04-01

    Cloud is one of the main processes in the climate system and especially a large feed back agent for Arctic warming amplification (Yoshimori et al., 2014). From this reason, observation of polar cloud has been emphasized and 95 GHz cloud profiling radar in high precision was established at Ny-Ålesund, Svalbard in 2013 as one of the basic infrastructure in the GRENE (Green Network of Excellence Program) Arctic Climate Change Research Project. The radar, "FALCON-A", is a FM-CW (frequency modulated continuous wave) Doppler radar, developed for Arctic use by Chiba University (PI: T. Takano) in 2012, following its prototype, "FALCON-1" which was developed in 2006 (Takano et al., 2010). The specifications of the radar are, central frequency: 94.84 GHz; antenna power: 1 W; observation height: up to 15 km; range resolution: 48 m; beam width: 0.2 degree (15 m at 5 km); Doppler width: 3.2 m/s; time interval: 10 sec, and capable of archiving high sensitivity and high spatial and time resolution. An FM-CW type radar realizes similar sensitivity with much smaller parabolic antennas separated 1.4 m from each other used for transmitting and receiving the wave. Polarized Micro-Pulse Lidar (PMPL, Sigma Space MPL-4B-IDS), which is capable to measure the backscatter and depolarization ratio, has also been deployed to Ny-Ålesund in March 2012, and now operated to perform collocated measurements with FALCON-A. Simultaneous measurement data from collocated PMPL and FALCON-A are available for synergetic analyses of cloud microphysics. Cloud mycrophysics, such as effective radius of ice particles and ice water content, are obtained from the analysis based on algorithm, which is modified for ground-based measurements from Okamoto's retrieval algorithm for satellite based cloud profiling radar and lidar (CloudSat and CALIPSO; Okamoto et al., 2010). Results of two years will be shown in the presentation. Calibration is a point to derive radar reflectivity (dBZ) from original intensity data

  10. The interpretation of remotely sensed cloud properties from a model paramterization perspective

    SciTech Connect

    Harshvardhan; Wielicki, B.A.; Ginger, K.M. |

    1994-12-01

    A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-1 data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 0.0625 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP 8-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction paramterization in a GCM when the model computes a grid-box-mean LWP.

  11. The interpretation of remotely sensed cloud properties from a model paramterization perspective

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN; Wielicki, Bruce A.; Ginger, Kathryn M.

    1994-01-01

    A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-1 data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 0.0625 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP 8-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction paramterization in a GCM when the model computes a grid-box-mean LWP.

  12. Dynamic subgrid heterogeneity of convective cloud in a global model: description and evaluation of the Convective Cloud Field Model (CCFM) in ECHAM6-HAM2

    NASA Astrophysics Data System (ADS)

    Kipling, Zak; Stier, Philip; Labbouz, Laurent; Wagner, Till

    2017-01-01

    The Convective Cloud Field Model (CCFM) attempts to address some of the shortcomings of both the commonly used bulk mass-flux parameterisations and those using a prescribed spectrum of clouds. By considering the cloud spectrum as a competitive system in which cloud types interact through their environment in competition for convective available potential energy (CAPE), the spectrum is able to respond dynamically to changes in the environment. An explicit Lagrangian entraining plume model for each cloud type allows for the representation of convective-cloud microphysics, paving the way for the study of aerosol-convection interactions at the global scale where their impact remains highly uncertain. In this paper, we introduce a new treatment of convective triggering, extending the entraining plume model below cloud base to explicitly represent the unsaturated thermals which initiate convection. This allows for a realistic vertical velocity to develop at cloud base, so that the cloud microphysics can begin with physically based activation of cloud condensation nuclei (CCN). We evaluate this new version of CCFM in the context of the global model ECHAM6-HAM, comparing its performance to the standard Tiedtke-Nordeng parameterisation used in that model. We find that the spatio-temporal distribution of precipitation is improved, both against a climatology from the Global Precipitation Climatology Project (GPCP) and also against diurnal cycles from the Tropical Rainfall Measurement Mission (TRMM) with a reduced tendency for precipitation to peak too early in the afternoon. Cloud cover is quite sensitive to the vertical level from which the dry convection is initiated, but when this is chosen appropriately the cloud cover compares well with that from Tiedtke-Nordeng. CCFM can thus perform as well as, or better than, the standard scheme while providing additional capabilities to represent convective-cloud microphysics and dynamic cloud morphology at the global scale.

  13. Citizen Science participation in the NASA CERES Students' Cloud Observations Online Project (S'COOL)

    NASA Astrophysics Data System (ADS)

    Lewis, P. M.; Moore, S.; Crecelius, S.; Rogerson, T.; Chambers, L. H.

    2012-12-01

    Many science programs designed for the classroom see little participation when school is not in session. Many factors, such as materials, cost, needing a teacher to lead discussion, and reporting/assessment criteria are classroom-centric. The S'COOL project has the ability to serve not only as a classroom-teaching tool, but as a citizen science project in which anyone can help NASA collect cloud data. Since its inception in 1997, the S'COOL project has invited help from the citizen science community from age 6 to 99. The S'COOL project has the ability to reach everyone in the world through satellite overpasses. This provides the citizen scientist with a temporal "match", i.e., the opportunity to make cloud observations "looking up" as various NASA Earth observing satellites make cloud observations "looking down" at the same location. After an observation is made, the observing scientist completes an online report form and sends this directly to NASA Langley Research Center's Atmospheric Science Data Center. After the satellite data are processed, generally within a week, an auto-generated email informs the observer of what the satellite observed, compared side-by-side with what they observed. All of the observations are stored in a database for later viewing and analysis. The ability to view satellite matches and past observations allows the citizen scientist to develop good scientific practices, particularly skills in cloud observation and data analysis techniques. Much of the success of the S'COOL project can be associated with its aim as a classroom-based program that transcends to the citizen science community. This allows both parties to have access to the same materials and data, creating an authentic science experience. Another avenue of success can be found in the project's translation of materials into French and Spanish. Translation provides a multicultural perspective and enables broader participation. Since the aim of the S'COOL project is to collect

  14. Situational Lightning Climatologies

    NASA Technical Reports Server (NTRS)

    Bauman, William; Crawford, Winifred

    2010-01-01

    Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. It was believed there were two flow systems, but it has been discovered that actually there are seven distinct flow regimes. The Applied Meteorology Unit (AMU) has recalculated the lightning climatologies for the Shuttle Landing Facility (SLF), and the eight airfields in the National Weather Service in Melbourne (NWS MLB) County Warning Area (CWA) using individual lightning strike data to improve the accuracy of the climatologies. The software determines the location of each CG lightning strike with 5-, 10-, 20-, and 30-nmi (.9.3-, 18.5-, 37-, 55.6-km) radii from each airfield. Each CG lightning strike is binned at 1-, 3-, and 6-hour intervals at each specified radius. The software merges the CG lightning strike time intervals and distance with each wind flow regime and creates probability statistics for each time interval, radii, and flow regime, and stratifies them by month and warm season. The AMU also updated the graphical user interface (GUI) with the new data.

  15. Evidence for liquid-phase cirrus cloud formation from volcanic aerosols - Climatic implications

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth

    1992-01-01

    Supercooled droplets in cirrus uncinus cell heads between -40 and -50 C are identified from the First International Satellite Cloud Climatology Project Regional Experiment polarization lidar measurements. Although short-lived, complexes of these small liquid cells seem to have contributed importantly to the formation of the cirrus. Freezing-point depression effects in solution droplets, apparently resulting from relatively large cloud condensation nuclei of volcanic origin, can be used to explain this rare phenomenon. An unrecognized volcano-cirrus cloud climate feedback mechanism is implied by these findings.

  16. Evidence for liquid-phase cirrus cloud formation from volcanic aerosols - Climatic implications

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth

    1992-01-01

    Supercooled droplets in cirrus uncinus cell heads between -40 and -50 C are identified from the First International Satellite Cloud Climatology Project Regional Experiment polarization lidar measurements. Although short-lived, complexes of these small liquid cells seem to have contributed importantly to the formation of the cirrus. Freezing-point depression effects in solution droplets, apparently resulting from relatively large cloud condensation nuclei of volcanic origin, can be used to explain this rare phenomenon. An unrecognized volcano-cirrus cloud climate feedback mechanism is implied by these findings.

  17. Multidecadal Changes in Near-Global Cloud Cover and Estimated Cloud Cover Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Norris, Joel

    2005-01-01

    The first paper was Multidecadal changes in near-global cloud cover and estimated cloud cover radiative forcing, by J. R. Norris (2005, J. Geophys. Res. - Atmos., 110, D08206, doi: lO.l029/2004JD005600). This study examined variability in zonal mean surface-observed upper-level (combined midlevel and high-level) and low-level cloud cover over land during 1971-1 996 and over ocean during 1952-1997. These data were averaged from individual synoptic reports in the Extended Edited Cloud Report Archive (EECRA). Although substantial interdecadal variability is present in the time series, long-term decreases in upper-level cloud cover occur over land and ocean at low and middle latitudes in both hemispheres. Near-global upper-level cloud cover declined by 1.5%-sky-cover over land between 1971 and 1996 and by 1.3%-sky-cover over ocean between 1952 and 1997. Consistency between EECRA upper-level cloud cover anomalies and those from the International Satellite Cloud Climatology Project (ISCCP) during 1984-1 997 suggests the surface-observed trends are real. The reduction in surface-observed upper-level cloud cover between the 1980s and 1990s is also consistent with the decadal increase in all-sky outgoing longwave radiation reported by the Earth Radiation Budget Satellite (EMS). Discrepancies occur between time series of EECRA and ISCCP low-level cloud cover due to identified and probable artifacts in satellite and surface cloud data. Radiative effects of surface-observed cloud cover anomalies, called "cloud cover radiative forcing (CCRF) anomalies," are estimated based on a linear relationship to climatological cloud radiative forcing per unit cloud cover. Zonal mean estimated longwave CCRF has decreased over most of the globe. Estimated shortwave CCRF has become slightly stronger over northern midlatitude oceans and slightly weaker over northern midlatitude land areas. A long-term decline in the magnitude of estimated shortwave CCRF occurs over low-latitude land and ocean

  18. Satellite Cloud Data Validation through MAGIC Ground Observation and the S'COOL Project: Scientific Benefits grounded in Citizen Science

    NASA Astrophysics Data System (ADS)

    Crecelius, S.; Chambers, L. H.; Lewis, P. M.; Rogerson, T.

    2013-12-01

    The Students' Cloud Observation On-Line (S'COOL) Project was launched in 1997 as the Formal Education and Public Outreach arm of the Clouds and the Earth's Radiant Energy System (CERES) Mission. ROVER, the Citizen Scientist area of S'COOL, started in 2007 and allows participants to make 'roving' observations from any location as opposed to a fixed, registered classroom. The S'COOL Project aids the CERES Mission in trying to answer the research question: 'What is the Effect of Clouds on the Earth's Climate'. Participants from all 50 states, most U.S. Territories, and 63 countries have reported more than 100,500 observations to the S'COOL Project over the past 16 years. The Project is supported by an intuitive website that provides curriculum support and guidance through the observation steps; 1) Request satellite overpass schedule, 2) Observe clouds, and 3) Report cloud observations. The S'COOL Website also hosts a robust database housing all participants' observations as well as the matching satellite data. While the S'COOL observation parameters are based on the data collected by 5 satellite missions, ground observations provide a unique perspective to data validation. Specifically, low to mid level clouds can be obscured by overcast high-level clouds, or difficult to observe from a satellite's perspective due to surface cover or albedo. In these cases, ground observations play an important role in filling the data gaps and providing a better, global picture of our atmosphere and clouds. S'COOL participants, operating within the boundary layer, have an advantage when observing low-level clouds that affect the area we live in, regional weather patterns, and climate change. S'COOL's long-term data set provides a valuable resource to the scientific community in improving the "poorly characterized and poorly represented [clouds] in climate and weather prediction models'. The MAGIC Team contacted S'COOL in early 2012 about making cloud observations as part of the MAGIC

  19. Cloud County Community College Wind Energy Technology Project and Renewable Energy Center of Excellence

    SciTech Connect

    Graham, Bruce

    2016-02-26

    Cloud County Community College's (CCCC) Wind Energy Technology (WET) program is a leader in the renewable energy movement across Kansas and the USA. The field of renewable energy is a growing industry which continues to experience high demand for career opportunities. This CCCC/DOE project entailed two phases: 1) the installation of two Northwind 100 wind turbines, and 2) the continued development of the WET program curriculum, including enhancement of the CCCC Blade Repair Certificate program. This report provides a technical account of the total work performed, and is a comprehensive description of the results achieved.

  20. An Examination of the Nature of Global MODIS Cloud Regimes

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji; Huffman, George J.

    2014-01-01

    We introduce global cloud regimes (previously also referred to as "weather states") derived from cloud retrievals that use measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua and Terra satellites. The regimes are obtained by applying clustering analysis on joint histograms of retrieved cloud top pressure and cloud optical thickness. By employing a compositing approach on data sets from satellites and other sources, we examine regime structural and thermodynamical characteristics. We establish that the MODIS cloud regimes tend to form in distinct dynamical and thermodynamical environments and have diverse profiles of cloud fraction and water content. When compositing radiative fluxes from the Clouds and the Earth's Radiant Energy System instrument and surface precipitation from the Global Precipitation Climatology Project, we find that regimes with a radiative warming effect on the atmosphere also produce the largest implied latent heat. Taken as a whole, the results of the study corroborate the usefulness of the cloud regime concept, reaffirm the fundamental nature of the regimes as appropriate building blocks for cloud system classification, clarify their association with standard cloud types, and underscore their distinct radiative and hydrological signatures.

  1. Diagnosing AIRS Sampling with CloudSat Cloud Classes

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric; Yue, Qing; Guillaume, Alexandre; Kahn, Brian

    2011-01-01

    AIRS yield and sampling vary with cloud state. Careful utilization of collocated multiple satellite sensors is necessary. Profile differences between AIRS and ECMWF model analyses indicate that AIRS has high sampling and excellent accuracy for certain meteorological conditions. Cloud-dependent sampling biases may have large impact on AIRS L2 and L3 data in climate research. MBL clouds / lower tropospheric stability relationship is one example. AIRS and CloudSat reveal a reasonable climatology in the MBL cloud regime despite limited sampling in stratocumulus. Thermodynamic parameters such as EIS derived from AIRS data map these cloud conditions successfully. We are working on characterizing AIRS scenes with mixed cloud types.

  2. On ISSM and leveraging the Cloud towards faster quantification of the uncertainty in ice-sheet mass balance projections

    NASA Astrophysics Data System (ADS)

    Larour, E.; Schlegel, N.

    2016-11-01

    With the Amazon EC2 Cloud becoming available as a viable platform for parallel computing, Earth System Models are increasingly interested in leveraging its capabilities towards improving climate projections. In particular, faced with long wait periods on high-end clusters, the elasticity of the Cloud presents a unique opportunity of potentially "infinite" availability of small-sized clusters running on high-performance instances. Among specific applications of this new paradigm, we show here how uncertainty quantification in climate projections of polar ice sheets (Antarctica and Greenland) can be significantly accelerated using the Cloud. Indeed, small-sized clusters are very efficient at delivering sensitivity and sampling analysis, core tools of uncertainty quantification. We demonstrate how this approach was used to carry out an extensive analysis of ice-flow projections on one of the largest basins in Greenland, the North-East Greenland Glacier, using the Ice Sheet System Model, the public-domain NASA-funded ice-flow modeling software. We show how errors in the projections were accurately quantified using Monte-Carlo sampling analysis on the EC2 Cloud, and how a judicious mix of high-end parallel computing and Cloud use can best leverage existing infrastructures, and significantly accelerate delivery of potentially ground-breaking climate projections, and in particular, enable uncertainty quantification that were previously impossible to achieve.

  3. Using Diurnal Temperature Range to Examine the Climatology of Solar Energy Potential

    NASA Astrophysics Data System (ADS)

    Zercher, C. N.; Hanrahan, J.; Murphy, S. Y.

    2015-12-01

    The potential for annual solar energy production largely depends on the amount of incoming shortwave radiation which is dependent on cloud cover. Due to natural large-scale climate variability, long-term cloud cover can vary substantially, therefore modifying the total energy that can be produced by solar cells in individual locations. Under anthropogenic climate change, future precipitation is expected to significantly deviate from observed values, therefore suggesting that cloud cover, and thus solar energy potential, will also change. The expected changes are both positive and negative depending on geographic region and can be highly spatially variable, particularly in regions of complex terrain. Because of the short-term availability of observed radiation and cloud cover data, it is difficult to study the historical climatology of solar energy potential, thus making future projections uncertain. Research has shown that another readily available climate variable, the diurnal temperature range, correlates well with daily averaged shortwave radiation values during months of minimal/no snow cover, and can thus serve as a proxy for shortwave radiation during the warm season throughout the period of record. In the present study, the diurnal temperature range is shown to be an excellent predictor of shortwave radiation around the state of Vermont, independent of latitude and elevation. Monte Carlo significance testing is also used to examine recent trends in this region.

  4. THE MAGELLANIC INTER-CLOUD PROJECT (MAGIC). I. EVIDENCE FOR INTERMEDIATE-AGE STELLAR POPULATIONS IN BETWEEN THE MAGELLANIC CLOUDS

    SciTech Connect

    Noeel, N. E. D.; Read, J. I.; Conn, B. C.; Rix, H.-W.; Carrera, R.

    2013-05-10

    The origin of the gas in between the Magellanic Clouds (MCs)-known as the ''Magellanic Bridge'' (MB)-is puzzling. Numerical simulations suggest that the MB formed from tidally stripped gas and stars in a recent interaction between the MCs. However, the apparent lack of stripped intermediate- or old-age stars associated with the MB is at odds with this picture. In this paper, we present the first results from the MAGellanic Inter-Cloud program (MAGIC) aimed at probing the stellar populations in the inter-Cloud region. We present observations of the stellar populations in two large fields located in between the Large and Small Magellanic Clouds (LMC/SMC), secured using the WFI camera on the 2.2 m telescope in La Silla. Using a synthetic color-magnitude diagram technique, we present the first quantitative evidence for the presence of intermediate-age and old stars in the inter-Cloud region. The intermediate-age stars-which make up {approx}28% of all stars in the region-are not present in fields at a similar distance from the SMC in a direction pointing away from the LMC. This provides potential evidence that these intermediate-age stars could have been tidally stripped from the SMC. However, spectroscopic studies will be needed to confirm or rule out the tidal origin for the inter-Cloud gas and stars.

  5. Cloud Distribution Statistics from LITE

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1998-01-01

    The Lidar In-Space Technology Experiment (LITE) mission has demonstrated the utility of spaceborne lidar in observing multilayer clouds and has provided a dataset showing the distribution of tropospheric clouds and aerosols. These unambiguous observations of the vertical distribution of clouds will allow improved verification of current cloud climatologies and GCM cloud parameterizations. Although there is now great interest in cloud profiling radar, operating in the mm-wave region, for the spacebased observation of cloud heights the results of the LITE mission have shown that satellite lidars can also make significant contributions in this area.

  6. Systematic Differences between Satellite-Based Presipitation Climatologies over the Tropical Oceans

    NASA Technical Reports Server (NTRS)

    Robertson, Frankin R.; Fitzjarrald, Dan; McCaul, Eugene W.

    1999-01-01

    Since the beginning of the World Climate Research Program's Global Precipitation Climatology Project (GPCP) satellite remote sensing of precipitation has made dramatic improvements, particularly for tropical regions. Data from microwave and infrared sensors now form the most critical input to precipitation data sets and can be calibrated with surface gauges to so that the strengths of each data source can be maximized in some statistically optimal sense. It is clear however that there still remain significant uncertainties with satellite precipitation retrievals which limit their usefulness for many purposes. Systematic differences i'A tropical precipitation estimates have been brought to light in comparison activities such as the GPCP Algorithm Intercomparison Project and more recent Wetnet Precipitation Intercomparison Project 3. These uncertainties are assuming more importance because of the demands for validation associated with global climate modeling and data assimilation methodologies. The objective of the present study is to determine the physical basis for systematic differences in spatial structure of tropical precipitation as portrayed by several different satellite-based data sets. The study is limited to oceanic regions only and deals primarily with aspects of spatial variability. We are specifically interested in why MSU channel 1 and GPI precipitation differences are so striking over the Eastern Pacific ITCZ and why they both differ from other microwave emission-based precipitation estimates from SSM/I and a scattering-based deep convective ice index from MSU channel 2. Our results to date have shown that MSU channel I precipitation estimates are biased high over the Eastern Pacific ITCZ because of two factors: (1) the hypersensitivity of this frequency to cloud water in contrast to falling rain drops, and (2) unaccounted for scattering effects by precipitation-size ice which depresses the signal of the liquid water emission. Likewise, cold cloud top

  7. Arctic ocean radiative fluxes and cloud forcing estimated from the ISCCP C2 cloud dataset, 1983-1990

    NASA Technical Reports Server (NTRS)

    Schweiger, Axel J.; Key, Jeffrey R.

    1994-01-01

    Radiative fluxes and cloud forcings for the ocean areas of the Arctic are computed from the monthly cloud product of the International Satellite Cloud Climatology Project (ISCCP) for 1983-90. Spatially averaged short-wave fluxes are compared well with climatological values, while downwelling longwave fluxes are significantly lower. This is probably due to the fact that the ISCCP cloud amounts are underestimates. Top-of-the-atmosphere radiative fluxes are in excellent agreement with measurements from the Earth Radiation Budget Experiment (ERBE). Computed cloud forcings indicate that clouds have a warming effect at the surface and at the top of the atmosphere during winter and a cooling effect during summer. The net radiative effect of clouds is larger at the surface during winter but greater at the top of the atmosphere during summer. Overall the net radiative effect of clouds at the top of the atmosphere is one of cooling. This is in contrast to a previous result from ERBE data showing arctic cloud forcings have a net warming effect. Sensitivities to errors in input parameters are generally greater during winter with cloud amount being the most important paarameter. During summer the surface radiation balance is most sensitive to errors in the measurements of surface reflectance. The results are encouraging, but the estimated error of 20 W/sq m in surface net radiative fluxes is too large, given that estimates of the net radiative warming effect due to a doubling of CO2 are on the order of 4 W/sq m. Because it is difficult to determine the accuracy of results with existing in situ observations, it is recommended that the development of improved algorithms for the retrieval of surface radiative properties be accompanied by the simultaneous assembly of validation datasets.

  8. Remote sensing cloud properties from simulated MODIS observations

    NASA Technical Reports Server (NTRS)

    Menzel, W. P.; Ackerman, Steven A.; Smith, William L.

    1991-01-01

    One of the objectives of the MODIS program is to establish a global cloud climatology that can address the effects of cirrus and opaque clouds on the Earth Radiation Budget. The paper describes the cloud retrieval techniques developed for MODIS-N IR observations and presents results of a study of remote sensing cloud properties using simulated MODIS observations at different cirrus cloud conditions.

  9. The DACCIWA project: Dynamics-aerosol-chemistry-cloud interactions in West Africa

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter

    2017-04-01

    This contribution provides an overview of the EU-funded DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) project. DACCIWA consists of 16 European and African research organisations and has strong links to universities, weather services and government organisations across West Africa. The project runs from 2010 to 2018 and is built around a major international field campaign in 2016. A key motivation for DACCIWA is the expected tripling of anthropogenic emissions in southern West Africa (SWA) between 2000 and 2030, whose impacts on human health, ecosystems, food security and the regional climate are largely unknown. An integrated assessment of this problem, which is mostly due to massive economic and population growth and urbanization, is challenging due to (a) a superposition of regional effects with global climate change, (b) a strong dependence on the variable West African monsoon, (c) incomplete scientific understanding of interactions between emissions, clouds, radiation, precipitation and regional circulations, and (d) a lack of observations. DACCIWA combines measurements in the field in SWA with extensive modelling activities and work on satellite data. In particular during the main DACCIWA field campaign in June-July 2016 high-quality observations of emissions, atmospheric composition and meteorological parameters were sampled. The campaign involved three research aircraft, three ground-based supersites, enhanced radiosonde launches, and intensive measurements at urban sites in Abidjan and Cotonou. These data have already been quality-controlled and will be freely available to the research community through a database at http://baobab.sedoo.fr/DACCIWA/ after the end of the project. The resulting benchmark dataset is currently combined with a wide range of modelling and satellite-based research activities that will ultimately allow (a) an assessment of the roles of relevant physical, chemical and biological processes, (b) an improvement

  10. The DACCIWA Project: Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter

    2014-05-01

    Massive economic and population growth and urbanisation are expected to lead to a tripling of anthropogenic emissions from southern West Africa (SWA) between 2000 and 2030, the impacts of which on human health, ecosystems, food security and the regional climate are largely unknown. An assessment of these impacts is complicated by (a) a superposition with effects of global climate change, (b) the strong dependence of SWA on the sensitive West African monsoon, (c) incomplete scientific understanding of interactions between emissions, clouds, radiation, precipitation and regional circulations and (d) by a lack of observations to advance our understanding and improve predictions. The purpose of this contribution is to introduce the research consortium DACCIWA (Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa), which comprises 16 partners in six European and West African countries. The interdisciplinary DACCIWA team will build on the scientific and logistical foundations established by the African Monsoon Multidisciplinary Analysis (AMMA) project and collaborate closely with operational centres. DACCIWA will receive funding of about M8.75€ from the European Commission as part of Framework Programme 7 from 2015 until 2018. The DACCIWA project will conduct extensive fieldwork in SWA to collect high-quality observations, spanning the entire process chain from surface-based natural and anthropogenic emissions to impacts on health, ecosystems and climate. This will include a major field campaign in summer 2015 with three research aircrafts and two ground-based supersites. Combining the resulting benchmark dataset with a wide range of modelling activities will allow us: (a) to assess all relevant physical and chemical processes, (b) to improve the monitoring of climate and compositional parameters from space, (c) to determine health impacts from air pollution, and (d) to develop the next generation of weather and climate models capable of representing coupled

  11. Cloud parameters estimated by variational analysis of visible and infrared measurements from ATSR-2

    NASA Astrophysics Data System (ADS)

    Watts, P.; Poulsen, C.

    2003-04-01

    The ATSR-2 instrument(a radiometer on board the ESA/ERS-2 satellite) produces images of the Earth at wavelengths(0.55, 0.67, 0.87, 1.6, 3.7, 10.9 and 12 um). ATSR-2 was launched in 1995 and was succeeded by AATSR on board the ENVISAT satellite in March 2002. Information on cloud properties from ATSR-2 radiances originates from the interaction of solar and emitted radiation with the cloud and in an ideal situation each channel of ATSR-2 would be sensitive to just one cloud property. In reality each measurement is the result of many complex interactions within the cloud and between the cloud, the atmosphere and the surface. In general however, cloud effects at the wavelengths measured (which are in atmospheric 'windows') are stronger or at least discernable from the other effects. By combining the information available we are able resolve the most important cloud parameters(i.e cloud hase, top height, effective radius cloud fraction and optical depth) in most situations. We use a Variational Analysis approach to the retrieval of parameters enabling us to extract information from all channels imultaneously. This method also allows us to characterize the error in each parameter in each individual observation (or 'pixel') under the assumption that the cloud observed is consistent with the modeled cloud (i.e. easonably plane-parallel in nature) and to identify where the cloud model is not appropriate. Climatological cloud data is currently being produced as part of the Cloudmap2 Framework5 program for the European area and as part of GRAPE project for the entire globe(see poster by Sam Dean/Steve Marsh in the same session) for the length of the ATSR-2 mission. This paper will explain the methodology behind the variational algorithm as well as show the validation of cases using aircraft data and ground based radar. Some first results from the climatology will be presented.

  12. Eight Year Climatologies from Observational (AIRS) and Model (MERRA) Data

    NASA Technical Reports Server (NTRS)

    Hearty, Thomas; Savtchenko, Andrey; Won, Young-In; Theobalk, Mike; Vollmer, Bruce; Manning, Evan; Smith, Peter; Ostrenga, Dana; Leptoukh, Greg

    2010-01-01

    We examine climatologies derived from eight years of temperature, water vapor, cloud, and trace gas observations made by the Atmospheric Infrared Sounder (AIRS) instrument flying on the Aqua satellite and compare them to similar climatologies constructed with data from a global assimilation model, the Modern Era Retrospective-Analysis for Research and Applications (MERRA). We use the AIRS climatologies to examine anomalies and trends in the AIRS data record. Since sampling can be an issue for infrared satellites in low earth orbit, we also use the MERRA data to examine the AIRS sampling biases. By sampling the MERRA data at the AIRS space-time locations both with and without the AIRS quality control we estimate the sampling bias of the AIRS climatology and the atmospheric conditions where AIRS has a lower sampling rate. While the AIRS temperature and water vapor sampling biases are small at low latitudes, they can be more than a few degrees in temperature or 10 percent in water vapor at higher latitudes. The largest sampling biases are over desert. The AIRS and MERRA data are available from the Goddard Earth Sciences Data and Information Services Center (GES DISC). The AIRS climatologies we used are available for analysis with the GIOVANNI data exploration tool. (see, http://disc.gsfc.nasa.gov).

  13. Antarctic Ultraviolet Radiation Climatology from Total Ozone Mapping Spectrometer Data

    NASA Technical Reports Server (NTRS)

    Lubin, Dan

    2004-01-01

    This project has successfully produced a climatology of local noon spectral surface irradiance covering the Antarctic continent and the Southern Ocean, the spectral interval 290-700 nm (UV-A, UV-B, and photosynthetically active radiation, PAR), and the entire sunlit part of the year for November 1979-December 1999. Total Ozone Mapping Spectrometer (TOMS) data were used to specify column ozone abundance and UV-A (360- or 380-nm) reflectivity, and passive microwave (MW) sea ice concentrations were used to specify the surface albedo over the Southern Ocean. For this latter task, sea ice concentration retrievals from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and its successor, the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) were identified with ultraviolet/visible-wavelength albedos based on an empirical TOMS/MW parameterization developed for this purpose (Lubin and Morrow, 2001). The satellite retrievals of surface albedo and UV-A reflectivity were used in a delta-Eddington radiative transfer model to estimate cloud effective optical depth. These optical depth estimates were then used along with the total ozone and surface albedo to calculate the downwelling spectral UV and PAR irradiance at the surface. These spectral irradiance maps were produced for every usable day of TOMS data between 1979-1999 (every other day early in the TOMS program, daily later on).

  14. Tornado climatology of Austria

    NASA Astrophysics Data System (ADS)

    Holzer, A. M.

    After several decades of little work, a revised tornado climatology for Austria is presented. Tornadoes seldom form in the alpine areas, however, near the eastern flanks of the Alps, favourable conditions for tornado genesis are found. Whereas in the alpine regions less than 0.3 tornadoes per 10,000 km 2 a year touch down (averaged for provinces or major parts of a province), we can count 0.9 in the greater Graz area, 1.0 in the greater Linz area and 1.2 tornadoes per 10,000 km 2 a year in the greater Vienna area, suggesting the existence of so-called tornado alleys. As these regions are the most populated areas of Austria, there is a possible population bias in the dataset. The overall average for Austria is 0.3 tornadoes per 10,000 km 2 a year. The database consists of 89 tornadoes, one landspout and six waterspouts, with a total of 96 events. The seasonal peak is in July with a maximum probability of tornadoes in the late afternoon and early evening hours. Every fifth tornado occurs in the hour after 5 p.m. The maximum intensity determined for a tornado in Austria was T7 on the TORRO-Scale (F3 on the Fujita-Scale), the most common intensity is T2 on the TORRO-Scale (F1 on the Fujita-Scale).

  15. Eight Years of High Cloud Statistics Using HIRS.

    NASA Astrophysics Data System (ADS)

    Wylie, Donald P.; Menzel, W. Paul

    1999-01-01

    Over the last 8 yr frequency and location of cloud observations have been compiled using multispectral High Resolution Infrared Radiation Sounder (HIRS) data from the National Oceanic and Atmospheric Administration polar-orbiting satellites; this work is an extension of the 4-yr dataset reported by D. Wylie et al. The CO2 slicing algorithm applied to the HIRS data exhibits a higher sensitivity to semitransparent cirrus clouds than the cloud algorithm used by the International Satellite Cloud Climatology Project; the threshold for cloud detection appears to require visible optical depths (vis) greater than 0.1.The geographical distributions of clouds in the 8-yr dataset are nearly the same as those reported from 4 yr of data. The detection of upper-tropospheric clouds occurs most often in the intertropical convergence zone and midlatitude storm belts with lower concentrations in subtropical deserts and oceanic subtropical highs. The areas of concentrated cloud cover exhibit latitudinal movement with the seasons as in other cloud datasets. HIRS finds clear sky in 25%, opaque cloud in 32%, and semitransparent cloud in 43% of all its observations. The effective emissivity of the all semitransparent clouds (vis < 6) ranges from 0.2 to 0.6 with an average value of about 0.5.Time trends are reexamined in detail. A possible cirrus increase in 1991 reported by Wylie and coauthors in 1994 is found to be diminished upon reinspection. The revised 8-yr record has indications of an increase in high clouds in the northern midlatitudes (0.5% yr1) but little change elsewhere. The seasonal cycle of cloud cover in the Southern Hemisphere becomes very noticeable in 1993.

  16. Evaluation of cloud prediction and determination of critical relative humidity for a mesoscale numerical weather prediction model

    SciTech Connect

    Seaman, N.L.; Guo, Z.; Ackerman, T.P.

    1996-04-01

    Predictions of cloud occurrence and vertical location from the Pennsylvannia State University/National Center for Atmospheric Research nonhydrostatic mesoscale model (MM5) were evaluated statistically using cloud observations obtained at Coffeyville, Kansas, as part of the Second International satellite Cloud Climatology Project Regional Experiment campaign. Seventeen cases were selected for simulation during a November-December 1991 field study. MM5 was used to produce two sets of 36-km simulations, one with and one without four-dimensional data assimilation (FDDA), and a set of 12-km simulations without FDDA, but nested within the 36-km FDDA runs.

  17. Application of the CERES Flux-by-Cloud Type Simulator to GCM Output

    NASA Technical Reports Server (NTRS)

    Eitzen, Zachary; Su, Wenying; Xu, Kuan-Man; Loeb, Norman G.; Sun, Moguo; Doelling, David R.; Bodas-Salcedo, Alejandro

    2016-01-01

    The CERES Flux By CloudType data product produces CERES top-of-atmosphere (TOA) fluxes by region and cloud type. Here, the cloud types are defined by cloud optical depth (t) and cloud top pressure (pc), with bins similar to those used by ISCCP (International Satellite Cloud Climatology Project). This data product has the potential to be a powerful tool for the evaluation of the clouds produced by climate models by helping to identify which physical parameterizations have problems (e.g., boundary-layer parameterizations, convective clouds, processes that affect surface albedo). Also, when the flux-by-cloud type and frequency of cloud types are simultaneously used to evaluate a model, the results can determine whether an unrealistically large or small occurrence of a given cloud type has an important radiative impact for a given region. A simulator of the flux-by-cloud type product has been applied to three-hourly data from the year 2008 from the UK Met Office HadGEM2-A model using the Langley Fu-Lour radiative transfer model to obtain TOA SW and LW fluxes.

  18. An evaluation of the effects of cloud parameterization in the R42L9 GCM

    NASA Astrophysics Data System (ADS)

    Wu, Tongwen; Wang, Zaizhi; Liu, Yimin; Yu, Rucong; Wu, Guoxiong

    2004-04-01

    Cloud is one of the uncertainty factors influencing the performance of a general circulation model (GCM). Recently, the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP) has developed a new version of a GCM (R42L9). In this work, roles of cloud parameterization in the R42L9 are evaluated through a comparison between two 20-year simulations using different cloud schemes. One scheme is that the cloud in the model is diagnosed from relative humidity and vertical velocity, and the other one is that diagnostic cloud is replaced by retrieved cloud amount from the International Satellite Cloud Climatology Project (ISCCP), combined with the amounts of high-, middle-, and low-cloud and heights of the cloud base and top from the NCEP. The boreal winter and summer seasonal means, as well as the annual mean, of the simulated top-of-atmosphere shortwave radiative flux, surface energy fluxes, and precipitation are analyzed in comparison with the observational estimates and NCEP reanalysis data. The results show that the scheme of diagnostic cloud parameterization greatly contributes to model biases of radiative budget and precipitation. When our derived cloud fractions are used to replace the diagnostic cloud amount, the top-of-atmosphere and surface radiation fields are better estimated as well as the spatial pattern of precipitation. The simulations of the regional precipitation, especially over the equatorial Indian Ocean in winter and the Asia-western Pacific region in summer, are obviously improved.

  19. Effects of observed horizontal inhomogeneities within cirrus clouds on solar radiative transfer

    NASA Astrophysics Data System (ADS)

    Buschmann, Nicole; McFarquhar, Greg M.; Heymsfield, Andrew J.

    2002-10-01

    In situ microphysical and combined radar and radiometer measurements of 11 cirrus clouds from Central Equatorial Pacific Experiment (CEPEX), European Cloud and Radiation Experiment (EUCREX), investigation of Clouds by Ground-Based and Airborne Radar and Lidar (CARL), and First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) are used to investigate effects of horizontal cloud inhomogeneities on solar radiative transfer. A three-dimensional ray-tracing model (GRIMALDI), based on the Monte Carlo method, is used to calculate upward and downward flux densities and absorption for the spectral range from 0.38 to 4.0 μm. Radiative flux densities are calculated using the inhomogeneous clouds derived from the observations and for horizontally and vertically averaged homogeneous clouds. Horizontally averaged values of radiative flux densities and absorption for heterogeneous clouds can differ by up to 30% from those calculated for the homogeneous clouds for convectively induced tropical cirrus clouds. The midlatitude cases examined tended to be more homogeneous, and hence differences between radiative properties for the homogeneous and heterogeneous clouds did not exceed 10%. For cirrus clouds with mean optical thicknesses smaller than 5 and with relative variances of optical thickness smaller than 0.2, errors caused by the homogeneous assumption are smaller than ±10%.

  20. Effects of clouds on the Earth radiation budget; Seasonal and inter-annual patterns

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.

    1992-01-01

    Seasonal and regional variations of clouds and their effects on the climatological parameters were studied. The climatological parameters surface temperature, solar insulation, short-wave absorbed, long wave emitted, and net radiation were considered. The data of climatological parameters consisted of about 20 parameters of Earth radiation budget and clouds of 2070 target areas which covered the globe. It consisted of daily and monthly averages of each parameter for each target area for the period, Jun. 1979 - May 1980. Cloud forcing and black body temperature at the top of the atmosphere were calculated. Interactions of clouds, cloud forcing, black body temperature, and the climatological parameters were investigated and analyzed.

  1. Northwest Africa - A Climatological Study,

    DTIC Science & Technology

    1996-08-01

    A climatological study of NorthwestAfrica, includingAlgeria, Tunisia, Morocco , Western Sahara, and the northern parts of Mauritania, Mali, and Niger...additional hazards. 14. Subject Terms: CLIMATOLOGY, METEOROLOGY, WEATHER, GEOGRAPHY, AFRICA, ALGERIA, MOROCCO , TUNISIA, WESTERN SAHARA, MAURITANIA, MALI, NIGER...line where mean annual rainfall exceeds 250 boundary. This zone includes most of Morocco , mm (the area south of this line is described in and the

  2. APhoRISM FP7 project: the Multi-platform volcanic Ash Cloud Estimation (MACE) infrastructure

    NASA Astrophysics Data System (ADS)

    Merucci, Luca; Corradini, Stefano; Bignami, Christian; Stramondo, Salvatore

    2014-05-01

    APHORISM is an FP7 project that aims to develop innovative products to support the management and mitigation of the volcanic and the seismic crisis. Satellite and ground measurements will be managed in a novel manner to provide new and improved products in terms of accuracy and quality of information. The Multi-platform volcanic Ash Cloud Estimation (MACE) infrastructure will exploit the complementarity between geostationary, and polar satellite sensors and ground measurements to improve the ash detection and retrieval and to fully characterize the volcanic ash clouds from source to the atmosphere. The basic idea behind the proposed method consists to manage in a novel manner, the volcanic ash retrievals at the space-time scale of typical geostationary observations using both the polar satellite estimations and in-situ measurements. The typical ash thermal infrared (TIR) retrieval will be integrated by using a wider spectral range from visible (VIS) to microwave (MW) and the ash detection will be extended also in case of cloudy atmosphere or steam plumes. All the MACE ash products will be tested on three recent eruptions representative of different eruption styles in different clear or cloudy atmospheric conditions: Eyjafjallajokull (Iceland) 2010, Grimsvotn (Iceland) 2011 and Etna (Italy) 2011-2012. The MACE infrastructure will be suitable to be implemented in the next generation of ESA Sentinels satellite missions.

  3. Cloud Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).

  4. Cloud Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).

  5. Depolarization ratio and attenuated backscatter for nine cloud types: analyses based on collocated CALIPSO lidar and MODIS measurements.

    PubMed

    Cho, Hyoun-Myoung; Yang, Ping; Kattawar, George W; Nasiri, Shaima L; Hu, Yongxiang; Minnis, Patrick; Trepte, Charles; Winker, David

    2008-03-17

    This paper reports on the relationship between lidar backscatter and the corresponding depolarization ratio for nine types of cloud systems. The data used in this study are the lidar returns measured by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite and the collocated cloud products derived from the observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua satellite. Specifically, the operational MODIS cloud optical thickness and cloud-top pressure products are used to classify cloud types on the basis of the International Satellite Cloud Climatology Project (ISCCP) cloud classification scheme. While the CALIPSO observations provide information for up to 10 cloud layers, in the present study only the uppermost clouds are considered. The layer-averaged attenuated backscatter (gamma') and layer-averaged depolarization ratio (delta) from the CALIPSO measurements show both water- and ice-phase features for global cirrus, cirrostratus, and deep convective cloud classes. Furthermore, we screen both the MODIS and CALIPSO data to eliminate cases in which CALIPSO detected two- or multi-layered clouds. It is shown that low gamma' values corresponding to uppermost thin clouds are largely eliminated in the CALIPSO delta-gamma' relationship for single-layered clouds. For mid-latitude and polar regions corresponding, respectively, to latitude belts 30 degrees -60 degrees and 60 degrees -90 degrees in both the hemispheres, a mixture of water and ice is also observed in the case of the altostratus class. MODIS cloud phase flags are also used to screen ice clouds. The resultant water clouds flagged by the MODIS algorithm show only water phase feature in the delta-gamma' relation observed by CALIOP; however, in the case of the ice clouds flagged by the MODIS algorithm, the co-existence of ice- and water-phase clouds is still observed in

  6. Application of Stochastic Radiative Transfer Theory to the ARM Cloud-Radiative Parameterization Problem

    SciTech Connect

    Dana E. Veron

    2012-04-09

    This project had two primary goals: (1) development of stochastic radiative transfer as a parameterization that could be employed in an AGCM environment, and (2) exploration of the stochastic approach as a means for representing shortwave radiative transfer through mixed-phase layer clouds. To achieve these goals, climatology of cloud properties was developed at the ARM CART sites, an analysis of the performance of the stochastic approach was performed, a simple stochastic cloud-radiation parameterization for an AGCM was developed and tested, a statistical description of Arctic mixed phase clouds was developed and the appropriateness of stochastic approach for representing radiative transfer through mixed-phase clouds was assessed. Significant progress has been made in all of these areas and is detailed in the final report.

  7. Temperature Dependence of Low Cloud Optical Thickness in the GISS GCM: Contributing Mechanisms and Climate Implications.

    NASA Astrophysics Data System (ADS)

    Tselioudis, George; Delgenio, Anthony D.; Kovari, William, Jr.; Yao, Mao-Sung

    1998-12-01

    A current-climate simulation of the Goddard Institute for Space Studies (GISS) GCM, which includes interactive cloud optical properties that depend on the predicted cloud water content, is analyzed to document the variations of low cloud optical thickness with temperature in the model atmosphere. It is found that low cloud optical thickness decreases with temperature in the warm subtropical and tropical latitudes and increases with temperature in the cold midlatitude regions. This behavior is in agreement with the results of two observational studies that analyzed satellite data from the International Satellite Cloud Climatology Project and Special Sensor Microwave/Imager datasets. The increase of low cloud optical thickness with temperature in the midlatitudes is due to vertical extent and cloud water increases, whereas the decrease with temperature in the warm latitudes is due to decreases in cloud water content and happens despite increases in cloud vertical extent. The cloud processes that produce the cloud property changes in the model also vary with latitude. In the midlatitude regions relative-humidity-induced increases of cloud vertical extent with temperature dominate, whereas in the Tropics increases in cloud-top entrainment and precipitation with temperature produce decreases of cloud water content, whose effect on optical thickness outweighs the effect of entrainment-induced increases of cloud vertical extent with temperature. Doubled-CO2 simulations with the GISS GCM suggest that even though low cloud optical thickness changes have little effect on the global climate sensitivity of the model, they redistribute the temperature change and reduce the high-latitude amplification of the greenhouse warming. It is also found that the current-climate variations of low cloud optical thickness with temperature reproduce qualitatively but overestimate quantitatively the changes in optical thickness with climate warming.

  8. Characterisation of secondary organic aerosol formed during cloud condensation-evaporation cycles from isoprene photooxidation (CUMULUS project)

    NASA Astrophysics Data System (ADS)

    Giorio, Chiara; Bregonzio, Lola; Siekmann, Frank; Temime-Roussel, Brice; Ravier, Sylvain; Pangui, Edouard; Tapparo, Andrea; Kalberer, Markus; Monod, Anne; Doussin, Jean-François

    2014-05-01

    Biogenic volatile organic compounds (BVOCs) undergo many reactions in the atmosphere and form a wide range of oxidised and water-soluble compounds. These compounds could partition into atmospheric water droplets, and react within the aqueous phase producing higher molecular weight and less volatile compounds which could remain in the particle phase after water evaporation (Ervens et al., 2011). The aim of this work is the characterisation of secondary organic aerosol (SOA) formed from the photooxidation of isoprene and the effect of cloud water on SOA formation and composition. The experiments were performed during the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere), at the 4.2 m3 stainless steel CESAM chamber at LISA (Wang et al., 2011). In each experiment, isoprene was injected in the chamber together with HONO under dry conditions before irradiation. Gas phase compounds were analyzed on-line by a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS), a Fourier Transform Infrared Spectrometer (FTIR), NOx and O3 analyzers. SOA formation and composition were analysed on-line with a Scanning Mobility Particle Sizer (SMPS) and an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS). Particular attention has been focused on SOA formation and aging during cloud condensation-evaporation cycles simulated in the smog chamber. In all experiments, we observed that during cloud formation water soluble gas-phase oxidation products readily partitioned into cloud droplets and new SOA was promptly produced which partly persisted after cloud evaporation. Chemical composition, elemental ratios and density of SOA, measured with the HR-ToF-AMS, were compared before, during cloud formation and after cloud evaporation. Experiments with other precursors, i.e. methacrolein, and effects of the presence of seeds were also investigated. Ervens, B. et al. (2011) Atmos. Chem. Phys. 11, 11069 11102. Wang, J. et al

  9. Evaluation of tropical cloud regimes in observations and a general circulation model

    NASA Astrophysics Data System (ADS)

    Chen, Yonghua; Del Genio, Anthony D.

    2009-02-01

    Tropical cloud regimes defined by cluster analysis of International Satellite Cloud Climatology Project (ISCCP) cloud top pressure (CTP)-optical thickness distributions and ISCCP-like Goddard Institute for Space Studies (GISS) general circulation model (GCM) output are analyzed in this study. The observations are evaluated against radar-lidar cloud-top profiles from the atmospheric radiation measurement (ARM) Program active remote sensing of cloud layers (ARSCL) product at two tropical locations and by placing them in the dynamical context of the Madden-Julian oscillation (MJO). ARSCL highest cloud-top profiles indicate that differences among some of the six ISCCP regimes may not be as prominent as suggested by ISCCP at the ARM tropical sites. An experimental adjustment of the ISCCP CTPs to produce cloud-top height profiles consistent with ARSCL eliminates the independence between those regimes. Despite these ambiguities, the ISCCP regime evolution over different phases of the MJO is consistent with existing MJO mechanisms, but with a greater mix of cloud types in each phase than is usually envisioned. The GISS Model E GCM produces two disturbed and two suppressed regimes when vertical convective condensate transport is included in the model’s cumulus parameterization. The primary model deficiencies are the absence of an isolated cirrus regime, a lack of mid-level cloud relative to ARSCL, and a tendency for occurrences of specific parameterized processes such as deep and shallow convection and stratiform low cloud formation to not be associated preferentially with any single cloud regime.

  10. Impact of aerosols on precipitation from deep convective clouds in eastern China

    NASA Astrophysics Data System (ADS)

    Jiang, Mengjiao; Li, Zhanqing; Wan, Bingcheng; Cribb, Maureen

    2016-08-01

    We analyzed the impact of aerosols on precipitation based on 3 years of 3-hourly observations made in heavily polluted eastern China. The probability of precipitation from different cloud types was calculated using International Satellite Cloud Climatology Project cloud data and gauge-based hourly precipitation data. Because deep convective clouds have the largest precipitation probability, the influence of aerosols on the precipitation from such clouds was studied in particular. Aerosol properties were taken from the Modern-Era Retrospective Analysis for Research and Applications Aerosol Reanalysis data set. As aerosol optical depth increased, rainfall amounts from deep convective clouds increased at first and then decreased. The descending part of the trend is likely due to the aerosol radiative effect. Downwelling solar radiative fluxes at the surface decreased as aerosol optical depth increased. The decrease in solar radiation led to a decrease in ground heat fluxes and convective available potential energy, which is unfavorable for development of convective clouds and precipitation. The tendencies for lower cloud top temperatures, lower cloud top pressures, and higher cloud optical depths as a response to larger aerosol optical depths suggest the invigoration effect. Vertical velocity, relative humidity, and air temperature from the National Centers for Environmental Prediction Climate Forecast System Reanalysis were sorted to help investigate if the trends are dependent on any environmental conditions. How dynamic and microphysical factors strengthen or mitigate the impact of aerosols on clouds and precipitation and more details about their interplay should be studied further using more observations and model simulations.

  11. HADS in the Large Magellanic Cloud: Initial findings from the SuperMACHO project

    SciTech Connect

    Garg, A

    2009-07-14

    The SuperMACHO Project is a five-year survey toward the Large Magellanic Cloud (LMC) aimed at understanding the nature of the populations of lenses responsible for the excess microlensing rates observed by the MACHO project. Survey observations were completed in 2006. A rich side-product of this survey is a catalog of variable sources down to a depth of VR 23, including many classes of pulsating variables such as {delta}-Scuti and RR Lyrae. Through their position in the Period-Luminosity diagram and their light curve characteristics we have identified 2323 high amplitude {delta}-Scuti (HADS) having high quality light curves. sing Fourier decomposition of the HADS light curves, we find that the period-luminosity (PL) relation defined by the firt-overtone (FO) pulsators does not show a clear separation from the PL-relation defined by the fundamental (F) pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. We also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax.

  12. Challenges and opportunities of cloud computing for atmospheric sciences

    NASA Astrophysics Data System (ADS)

    Pérez Montes, Diego A.; Añel, Juan A.; Pena, Tomás F.; Wallom, David C. H.

    2016-04-01

    Cloud computing is an emerging technological solution widely used in many fields. Initially developed as a flexible way of managing peak demand it has began to make its way in scientific research. One of the greatest advantages of cloud computing for scientific research is independence of having access to a large cyberinfrastructure to fund or perform a research project. Cloud computing can avoid maintenance expenses for large supercomputers and has the potential to 'democratize' the access to high-performance computing, giving flexibility to funding bodies for allocating budgets for the computational costs associated with a project. Two of the most challenging problems in atmospheric sciences are computational cost and uncertainty in meteorological forecasting and climate projections. Both problems are closely related. Usually uncertainty can be reduced with the availability of computational resources to better reproduce a phenomenon or to perform a larger number of experiments. Here we expose results of the application of cloud computing resources for climate modeling using cloud computing infrastructures of three major vendors and two climate models. We show how the cloud infrastructure compares in performance to traditional supercomputers and how it provides the capability to complete experiments in shorter periods of time. The monetary cost associated is also analyzed. Finally we discuss the future potential of this technology for meteorological and climatological applications, both from the point of view of operational use and research.

  13. The MACHO Project HST Follow-Up: The Large Magellanic Cloud Microlensing Source Stars

    SciTech Connect

    Nelson, C.A.; Drake, A.J.; Cook, K.H.; Bennett, D.P.; Popowski, P.; Dalal, N.; Nikolaev, S.; Alcock, C.; Axelrod, T.S.; Becker, A.C. Freeman, K.C.; Geha, M.; Griest, K.; Keller, S.C.; Lehner, M.J.; Marshall, S.L.; Minniti, D.; Pratt, M.R.; Quinn, P.J.; Stubbs, C.W.; Sutherland, W.; /Oxford U. /Oran, Sci. Tech. U. /Garching, Max Planck Inst. /McMaster U.

    2009-06-25

    We present Hubble Space Telescope (HST) WFPC2 photometry of 13 microlensed source stars from the 5.7 year Large Magellanic Cloud (LMC) survey conducted by the MACHO Project. The microlensing source stars are identified by deriving accurate centroids in the ground-based MACHO images using difference image analysis (DIA) and then transforming the DIA coordinates to the HST frame. None of these sources is coincident with a background galaxy, which rules out the possibility that the MACHO LMC microlensing sample is contaminated with misidentified supernovae or AGN in galaxies behind the LMC. This supports the conclusion that the MACHO LMC microlensing sample has only a small amount of contamination due to non-microlensing forms of variability. We compare the WFPC2 source star magnitudes with the lensed flux predictions derived from microlensing fits to the light curve data. In most cases the source star brightness is accurately predicted. Finally, we develop a statistic which constrains the location of the Large Magellanic Cloud (LMC) microlensing source stars with respect to the distributions of stars and dust in the LMC and compare this to the predictions of various models of LMC microlensing. This test excludes at {approx}> 90% confidence level models where more than 80% of the source stars lie behind the LMC. Exotic models that attempt to explain the excess LMC microlensing optical depth seen by MACHO with a population of background sources are disfavored or excluded by this test. Models in which most of the lenses reside in a halo or spheroid distribution associated with either the Milky Way or the LMC are consistent which these data, but LMC halo or spheroid models are favored by the combined MACHO and EROS microlensing results.

  14. The hydroclimatic and ecophysiological basis of cloud forest distributions under current and projected climates

    PubMed Central

    Oliveira, Rafael S.; Eller, Cleiton B.; Bittencourt, Paulo R. L.; Mulligan, Mark

    2014-01-01

    Background Tropical montane cloud forests (TMCFs) are characterized by a unique set of biological and hydroclimatic features, including frequent and/or persistent fog, cool temperatures, and high biodiversity and endemism. These forests are one of the most vulnerable ecosystems to climate change given their small geographic range, high endemism and dependence on a rare microclimatic envelope. The frequency of atmospheric water deficits for some TMCFs is likely to increase in the future, but the consequences for the integrity and distribution of these ecosystems are uncertain. In order to investigate plant and ecosystem responses to climate change, we need to know how TMCF species function in response to current climate, which factors shape function and ecology most and how these will change into the future. Scope This review focuses on recent advances in ecophysiological research of TMCF plants to establish a link between TMCF hydrometeorological conditions and vegetation distribution, functioning and survival. The hydraulic characteristics of TMCF trees are discussed, together with the prevalence and ecological consequences of foliar uptake of fog water (FWU) in TMCFs, a key process that allows efficient acquisition of water during cloud immersion periods, minimizing water deficits and favouring survival of species prone to drought-induced hydraulic failure. Conclusions Fog occurrence is the single most important microclimatic feature affecting the distribution and function of TMCF plants. Plants in TMCFs are very vulnerable to drought (possessing a small hydraulic safety margin), and the presence of fog and FWU minimizes the occurrence of tree water deficits and thus favours the survival of TMCF trees where such deficits may occur. Characterizing the interplay between microclimatic dynamics and plant water relations is key to foster more realistic projections about climate change effects on TMCF functioning and distribution. PMID:24759267

  15. A global monthly sea surface temperature climatology

    NASA Technical Reports Server (NTRS)

    Shea, Dennis J.; Trenberth, Kevin E.; Reynolds, Richard W.

    1992-01-01

    The paper presents a new global 2 deg x 2 deg monthly sea surface temperature (SST) climatology, referred here to as the Shea-Trenberth-Reynolds (STR) climatology, which was derived by modifying a 1950-1979-based SST climatology from the Climate Analysis Center (CAC), by using data from the Comprehensive Ocean-Atmosphere Data Set to improve the SST estimates in the regions of the Kuroshio and the Gulf Stream. A comparison of the STR climatology with the Alexander and Mobley SST climatology showed that the STR climatology is warmer in the Northern Hemisphere, and colder poleward of 45 deg S.

  16. A global monthly sea surface temperature climatology

    NASA Technical Reports Server (NTRS)

    Shea, Dennis J.; Trenberth, Kevin E.; Reynolds, Richard W.

    1992-01-01

    The paper presents a new global 2 deg x 2 deg monthly sea surface temperature (SST) climatology, referred here to as the Shea-Trenberth-Reynolds (STR) climatology, which was derived by modifying a 1950-1979-based SST climatology from the Climate Analysis Center (CAC), by using data from the Comprehensive Ocean-Atmosphere Data Set to improve the SST estimates in the regions of the Kuroshio and the Gulf Stream. A comparison of the STR climatology with the Alexander and Mobley SST climatology showed that the STR climatology is warmer in the Northern Hemisphere, and colder poleward of 45 deg S.

  17. Remote sensing of multilevel clouds during FIRE IFO 2

    NASA Technical Reports Server (NTRS)

    Baum, Bryan A.; Titlow, J.; Tovinkere, V.; Poellot, M.; Ackerman, T. P.; Alvarez, J.; Uttal, T.; Intrieri, J.

    1993-01-01

    An unresolved difficulty in the remote sensing of clouds concerns the inability of the cloud retrieval algorithms to adequately recognize and analyze scenes containing overlapping cloud layers. Most cloud retrieval schemes, such as that used by the International Satellite Cloud Climatology Project (ISCCP) assume that each picture element (pixel) contains a single cloud layer. The current study begins to address the complexities of multilayered cloud property retrieval through the application of a modified multispectral, multiresolution (MSMR) method, first detailed in Baum et al. (1992), which merges 1.1 -km (at nadir) spectral data from the Advanced Very High Resolution Radiometer (AVHRR) with 17.4-km (at nadir) High Resolution Infrared Radiometer Sounder (HIRS/2, henceforth HIRS). Both instruments are flown aboard the National Oceanic and Atmospheric Administration (NOAA) polar-orbiting platforms. An ideal case study for this investigation is provided by the NOAA-11 overpass at 20:48 UTC on November 28, 1991. At this time, a large-scale cirrostratus veil overlaid a low-level stratus deck over much of the IFO region. There were both surface lidar and radar observations of the clouds as well as University of North Dakota (UND) Citation aircraft measurements. The presence of overlapping cloud layers within a HIRS FOV is determined from colocated AVHRR spectral data through the use of a fuzzy logic expert system. Conventional algorithms such as spatial coherence and CO2 slicing are used to retrieve cloud pressure and height for each identified cloud layer. The results from the satellite cloud retrieval analysis are compared to results from both surface- and aircraft-based measurements.

  18. Eight Year Climatology from observational (AIRS) and model (MERRA) data

    NASA Astrophysics Data System (ADS)

    Hearty, T. J.; Savtchenko, A. K.; Won, Y.; Theobald, M.; Vollmer, B.; Manning, E.; Smith, P. M.; Ostrenga, D.; Leptoukh, G. G.

    2010-12-01

    We examine climatologies derived from eight years of temperature, water vapor, cloud, and trace gas observations made by the Atmospheric Infrared Sounder (AIRS) instrument flying on the Aqua satellite and compare them to similar climatologies constructed with data from a global assimilation model, the Modern Era Retrospective-Analysis for Research and Applications (MERRA). We use the AIRS climatologies to examine anomalies and trends in the AIRS data record. Since sampling can be an issue for infrared satellites in low earth orbit, we also use the MERRA data to examine the AIRS sampling biases. By sampling the MERRA data at the AIRS space-time locations both with and without the AIRS quality control we estimate the sampling bias of the AIRS climatology and the atmospheric conditions where AIRS has a lower sampling rate. While the AIRS temperature and water vapor sampling biases are small at low latitudes, they can be more than a few degrees in temperature or 10 percent in water vapor at higher latitudes. The largest sampling biases are over desert.

  19. Cirrus cloud properties derived from coincident GOES and lidar data during the 1986 FIRE Cirrus Intensive Field Observations (IFO)

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Alvarez, Jose M.; Young, David F.; Heck, Patrick W.; Sassen, Kenneth

    1990-01-01

    One of the main difficulties in detecting cirrus clouds and determining their correct altitude using satellite measurements is their nonblackness. In the present algorithm (Rossow et al., 1985) used by the International Satellite Cloud Climatology Project (ISCCP), the cirrus cloud emissivity is estimated from the derived cloud reflectance using a theoretical model relating visible (VIS, 0.65 micron) optical depth to infrared (IR, 10.5 micron) emissivity. At this time, it is unknown how accurate this approach is or how the derived cloud altitude relates to the physical properties of the cloud. The First ISCCP Regional Experiment (FIRE) presents opportunities for determining how the observed radiances depend on the cloud properties. During the FIRE Cirrus Intensive Field Observations (IFO, see Starr, 1987), time series of cloud thickness, height, and relative optical densities were measured from several surface-based lidars. Cloud microphysics and radiances at various wavelengths were also measured simultaneously over these sites from aircraft at specific times during the IFO (October 19 to November 2, 1986). Satellite-observed radiances taken simultaneously can be matched with these data to determine their relationships to the cirrus characteristics. The first step is taken toward relating all of these variables to the satellite observations. Lidar-derived cloud heights are used to determine cloud temperatures which are used to estimate cloud emissivities from the satellite IR radiances. These results are then correlated to the observed VIS reflectances for various solar zenith angles.

  20. Cloud fields derived from satellite and surface data during FIRE cirrus phase 2

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Smith, William L., Jr.; Young, David F.; Heck, Patrick W.

    1993-01-01

    The interpretation of surface and aircraft measurements of cloud properties taken during field programs must take into account the large-scale cloud and meteorological conditions. Cloud properties are also required at scales beyond the point and line data taken from ground and aircraft platforms. Satellite data can provide a quantitative description of these large-scale cloud properties. When derived from geostationary satellite data, the cloud fields constitute a unique source for evaluating the development and demise of a cloud system. Satellites, however, can only see the tops of clouds, so that cloud layers below the uppermost cloud deck may remain undetected resulting in a incomplete depiction of the cloud system. Some multilayer clouds are amenable to detection from satellites. Many, especially in midlatitude cyclonic systems, can only be observed from the surface. A combination of surface and satellite cloud observations should be the most complete quantification of large-scale cloudiness if there are sufficient surface measurements. During the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment Phase 2 (FIRE-2) Cirrus Intensive Field Observation (IFO) period (November 13 - December 7, 1991) conducted at Coffeyville, Kansas, cirrus observations were taken in a variety of conditions. The IFO area was selected for a variety of reasons including the relatively dense network of surface weather stations and special surface instrumentation sites. Thus, the FIRE-2 IFO presents an excellent opportunity to combine cloud observations from surface and satellite observations. This paper presents an analysis of cloud properties on a mesoscale grid using satellite cloud property retrievals, surface observer data, and rawinsonde temperature and humidity profiles.

  1. Characterisation of Secondary Organic Aerosol Formed from the Photooxidation of Isoprene during Cloud Condensation-Evaporation Cycles (CUMULUS Project)

    NASA Astrophysics Data System (ADS)

    Doussin, J. F.; Giorio, C.; Bregonzio-Rozier, L.; Siekmann, F.; Temime-Roussel, B.; Gratien, A.; Ravier, S.; Pangui, E.; Tapparo, A.; Kalberer, M.; Vermeylen, R.; Claeys, M.; Monod, A.

    2014-12-01

    Biogenic volatile organic compounds (BVOCs) undergo many oxidation processes in the atmosphere accompanied by formation of water-soluble compounds. These compounds could partition into atmospheric water droplets, and react within the aqueous phase producing higher molecular weight and less volatile compounds which could form new aerosol (Ervens et al., 2011). This work investigates the formation and composition of secondary organic aerosol (SOA) from the photooxidation of isoprene and methacrolein (its main first-generation oxidation product) and the effect of cloud water on SOA formation and composition. The experiments were performed within the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere) at the 4.2 m3 stainless steel CESAM chamber (Wang et al., 2011). In each experiment, isoprene or methacrolein was injected in the chamber together with HONO under dry conditions before irradiation. The experimental protocol was optimised to generate cloud events in the chamber, lasting for ca. 10 minutes in the presence of light. Gas phase compounds were analyzed on-line by a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS), a Fourier Transform Infrared Spectrometer (FTIR), NOx and O3 analyzers. SOA formation and composition were analysed on-line with a Scanning Mobility Particle Sizer (SMPS) and an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and off-line through sampling on filters and analysis in GC-MS and LC-MS. We observed that during cloud formation water soluble gas-phase oxidation products readily partitioned into cloud droplets and new SOA was promptly produced. Chemical composition, elemental ratios and density of SOA were compared before, during cloud formation and after cloud evaporation. Ervens, B. et al. (2011) Atmos. Chem. Phys. 11, 11069-11102. Wang, J. et al. (2011) Atmos. Measur. Tech. 4, 2465-2494.

  2. The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6.

    NASA Technical Reports Server (NTRS)

    Webb, Mark J.; Andrews, Timothy; Bodas-Salcedo, Alejandro; Bony, Sandrine; Bretherton, Christopher S.; Chadwick, Robin; Chepfer, Helene; Douville, Herve; Good, Peter; Kay, Jennifer E.; Tselioudis, George

    2017-01-01

    The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud-climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions 'How does the Earth system respond to forcing?' and 'What are the origins and consequences of systematic model biases?' and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity. A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in precipitation

  3. The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6.

    NASA Technical Reports Server (NTRS)

    Webb, Mark J.; Andrews, Timothy; Bodas-Salcedo, Alejandro; Bony, Sandrine; Bretherton, Christopher S.; Chadwick, Robin; Chepfer, Helene; Douville, Herve; Good, Peter; Kay, Jennifer E.; hide

    2017-01-01

    The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud-climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions 'How does the Earth system respond to forcing?' and 'What are the origins and consequences of systematic model biases?' and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity. A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in precipitation

  4. Variability of Clouds Over a Solar Cycle

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    2002-01-01

    One of the most controversial aspects of climate studies is the debate over the natural and anthropogenic causes of climate change. Historical data strongly suggest that the Little Ice Age (from 1550 to 1850 AD when the mean temperature was colder by about 1 C) was most likely caused by variability of the sun and not greenhouse molecules (e.g., CO2). However, the known variability in solar irradiance and modulation of cosmic rays provides too little energy, by many orders of magnitude, to lead to climate changes in the troposphere. The conjecture is that there is a 'trigger mechanism'. This idea may now be subjected to a quantitative test using recent global datasets. Using the best available modern cloud data from International Satellite Cloud Climatology Project (ISCCP), Svensmark and Friis-Christensen found a correlation of a large variation (3-4%) in global cloud cover with the solar cycle. The work has been extended by Svensmark and Marsh and Svensmark. The implied forcing on climate is an order of magnitude greater than any previous claims. Are clouds the long sought trigger mechanism? This discovery is potentially so important that it should be corroborated by an independent database, and, furthermore, it must be shown that alternative explanations (i.e., El Nino) can be ruled out. We used the ISCCP data in conjunction with the Total Ozone Mapping Spectrometer (TOMS) data to carry out in in depth study of the cloud trigger mechanism.

  5. The HOAPS-II climatology - Release II of the satellite-derived freshwater flux climatology

    NASA Astrophysics Data System (ADS)

    Fennig, K.; Klepp, C.; Bakan, S.; Schulz, J.; Graßl, H.

    2003-04-01

    HOAPS-II (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data) is the improved global climatology of sea surface parameters and surface energy and freshwater fluxes derived from satellite radiances for the time period July 1987 until the recent dates. Data from polar orbiting radiometers, all available Special Sensor Microwave/Imager (SSM/I) radiometers and the Advanced Very High Resolution Radiometer (AVHRR), have been used to get global fields of surface meteorological and oceanographic parameters but also latent heat flux, evaporation, precipitation and net freshwater flux as well as the wind speed, water vapor- and total water content over ice free ocean areas for various averaging periods and grid sizes including scan orientated data in the NetCDF data format. All retrieval methods have been validated with in situ data on a global scale with a focus on precipitation validation. The new release of the data base is freely available to the community. Additionally, applications of the HOAPS-II data base will demonstrate its ability to detect ground validated High Impact Weather over global oceans that the Global Precipitation Climatology Project (GPCP) climatology and the ECMWF model is frequently missing. Nowcasting of model-unpredicted storms is a high potential application of this new data base.

  6. The effect of cloud type on earth's energy balance - Results for selected regions

    NASA Technical Reports Server (NTRS)

    Ockert-Bell, Maureen E.; Hartmann, Dennis L.

    1992-01-01

    International Satellite Cloud Climatology Project (ISCCP) C1 cloud information is compared with planetary albedo, outgoing longwave radiation (OLR), and net radiation measured at the top of the atmosphere by the Earth Radiation Budget Experiment (ERBE). Principal component analysis indicates that the day-to-day variations of the abundances of the 35 cloud types of the C1 data are correlated with each other, so that for many purposes the data set can be well represented by about five cloud types. Using stepwise multiple regression, the ISCCP C1 data can be used to predict the day-to-day variations of the energy balance measured by ERBE for 2.5-deg regions. Total fractional area coverage of cloudiness is a relatively poor predictor of radiation budget quantities. If the total fractional area coverage by clouds is divided into contributions from several distinct cloud types, the fractional coverages by these several cloud types will together form a much better prediction of radiation budget quantities than the single variable of total fractional-area cloud coverage. The regression equations can be used to estimate the net effect of clouds on the radiation balance and the contributions from particular types of clouds to albedo, OLR, and net radiation.

  7. The effect of cloud type on earth's energy balance - Results for selected regions

    NASA Technical Reports Server (NTRS)

    Ockert-Bell, Maureen E.; Hartmann, Dennis L.

    1992-01-01

    International Satellite Cloud Climatology Project (ISCCP) C1 cloud information is compared with planetary albedo, outgoing longwave radiation (OLR), and net radiation measured at the top of the atmosphere by the Earth Radiation Budget Experiment (ERBE). Principal component analysis indicates that the day-to-day variations of the abundances of the 35 cloud types of the C1 data are correlated with each other, so that for many purposes the data set can be well represented by about five cloud types. Using stepwise multiple regression, the ISCCP C1 data can be used to predict the day-to-day variations of the energy balance measured by ERBE for 2.5-deg regions. Total fractional area coverage of cloudiness is a relatively poor predictor of radiation budget quantities. If the total fractional area coverage by clouds is divided into contributions from several distinct cloud types, the fractional coverages by these several cloud types will together form a much better prediction of radiation budget quantities than the single variable of total fractional-area cloud coverage. The regression equations can be used to estimate the net effect of clouds on the radiation balance and the contributions from particular types of clouds to albedo, OLR, and net radiation.

  8. Cloud cover analysis with Arctic AVHRR data: 1. Cloud detection

    NASA Astrophysics Data System (ADS)

    Key, J.; Barry, R. G.

    1989-12-01

    Automated analyses of satellite radiance data have concentrated heavily on low and middle latitude situations. Some of the design objectives for the International Satellite Cloud Climatology Project (ISCCP) cloud detection procedure such as space and time contrasts are used in a basic algorithm from which a polar cloud detection algorithm is developed. This algorithm is applied to Arctic data for January and July conditions. Both advanced very high resolution radiometer (AVHRR) and scanning multichannel microwave radiometer (SMMR) data are utilized. Synthetic AVHRR and SMMR data for a 7-day analysis period are also generated to provide a data set with known characteristics on which to test and validate algorithms. Modifications to the basic algorithm for polar conditions include the use of SMMR and SMMR-derived data sets for the estimation of surface parameters, elimination of the spatial test for the warmest pixel, the use of AVHRR channels 1 (0.7 μm), 3 (3.7 μm), and 4 (11 μm) in the temporal tests and the final multispectral thresholding, and the use of surface class characteristic values when clear-sky values cannot be obtained. Additionally, the difference between channels 3 and 4 is included in the temporal test for the detection of optically thin cloud. Greatest improvement in computed cloud fraction is realized over snow and ice surfaces; over open water or snow-free land, all versions perform similarly. Since the inclusion of SMMR for surface analysis and additional spectral channels increases the computational burden, its use may be justified only over snow and ice-covered regions.

  9. Heat and moisture fluxes within a nighttime maritime stratus cloud during CASP II

    SciTech Connect

    Gultepe, I.; Issac, G.

    1994-12-31

    Stratus clouds in the lower part of the atmosphere over the ocean or land can play an important role in boundary layer processes and in climate change. Physical, dynamical, and radiative processes within marine stratus clouds on both cloud and regional scale are studied for the first time during the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE) (Albrecht et al., 1988). These clouds can effect the nowcasting, pollution transfer, and radiative processes (Nicholls and Leighton, 1986). Similar to the FIRE stratus project, the Canadian Atlantic Storms Program (CASP) II field project was planned to obtain a better understanding of cloud physical, dynamical, radiative characteristics, and mesoscale structure of Canadian east coast storms. Here the dynamical and microphysical data, and a radiative transfer model are used to better understand a developing nighttime stratus cloud over the ocean during CASP II which took place over Atlantic Canada. Observations collected by the Convair aircraft of the National Research Council (NRC) of Canada during the CASP II field project on February 6, 1991 are presented.

  10. Radiative Effect of Clouds on Tropospheric Chemistry: Sensitivity to Cloud Vertical Distributions and Optical Properties

    NASA Astrophysics Data System (ADS)

    Liu, H.; Crawford, J. H.; Pierce, R. B.; Considine, D. B.; Logan, J. A.; Duncan, B. N.; Norris, P.; Platnick, S. E.; Chen, G.; Yantosca, R. M.; Evans, M. J.

    2005-12-01

    Representation of clouds in global models poses a significant challenge since most cloud processes occur on sub-grid scales and must be parameterized. Uncertainties in cloud distributions and optical properties are therefore a limiting factor in model assessments of the radiative effect of clouds on global tropospheric chemistry. We present an analysis of the sensitivity of the radiative effect of clouds to cloud vertical distributions and optical properties with the use of the GEOS-CHEM global 3-D chemistry transport model coupled with the Fast-J radiative transfer algorithm. GEOS-CHEM was driven with a series of meteorological archives (GEOS1-STRAT, GEOS-3, and GEOS-4) generated by the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA global Modeling and Assimilation Office (GMAO), which have significantly different cloud optical depths and vertical distributions. The column cloud optical depths in GEOS-3 generally agree with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP) within ±10%, while those in GEOS1-STRAT and GEOS-4 are too low by factors of about 5 and 2, respectively. With respect to vertical distribution, clouds in GEOS-4 are optically much thinner in the tropical upper troposphere compared to those in GEOS1-STRAT and GEOS-3. Assuming linear scaling of cloud optical depth with cloud fraction in a grid-box, our model calculations indicate that the changes in global mean hydroxyl radical (OH) due to the radiative effect of clouds in June are about -1% (GEOS1-STRAT), 1% (GEOS-3), and 14% (GEOS-4), respectively. The effects on global mean OH are similar for GEOS1-STRAT and GEOS-3 due to similar vertical distributions of clouds, even though the column cloud optical depths in the two archives differ by a factor of about 5. Clouds in GEOS-4 have a much larger impact on global mean OH because more solar radiation is

  11. Shortwave cloud-radiative forcing at the top of the atmosphere at the surface and of the atmospheric column as determined from ISCCP C1 data

    NASA Technical Reports Server (NTRS)

    Laszlo, Istvan; Pinker, Rachel T.

    1993-01-01

    The paper employs the C1 data of the International Satellite Cloud Climatology Project, along with the Satellite Algorithm for Shortwave Radiation Budget, to estimate the shortwave cloud effects in terms of the cloud-radiative forcing at the top of the atmosphere (TOA) and at the surface, and that of the atmospheric column on a global scale for the July months of 1983-1985. The cloud forcing for July 1985 is underestimated, by about 8/sq Wm, compared with that obtained from the Earth Radiation Budget Experiment. The cloud forcing at the surface is almost identical to that at the TOA, indicating that the effect of clouds on the shortwave energy budget of the surface-atmosphere system is such that most of the cooling is at the surface.

  12. The Climatology of Australian Aerosol

    NASA Astrophysics Data System (ADS)

    Mitchell, Ross M.; Forgan, Bruce W.; Campbell, Susan K.

    2017-04-01

    Airborne particles or aerosols have long been recognised for their major contribution to uncertainty in climate change. In addition, aerosol amounts must be known for accurate atmospheric correction of remotely sensed images, and are required to accurately gauge the available solar resource. However, despite great advances in surface networks and satellite retrievals over recent years, long-term continental-scale aerosol data sets are lacking. Here we present an aerosol assessment over Australia based on combined sun photometer measurements from the Bureau of Meteorology Radiation Network and CSIRO/AeroSpan. The measurements are continental in coverage, comprising 22 stations, and generally decadal in timescale, totalling 207 station-years. Monthly climatologies are given at all stations. Spectral decomposition shows that the time series can be represented as a weighted sum of sinusoids with periods of 12, 6 and 4 months, corresponding to the annual cycle and its second and third harmonics. Their relative amplitudes and phase relationships lead to sawtooth-like waveforms sharply rising to an austral spring peak, with a slower decline often including a secondary peak during the summer. The amplitude and phase of these periodic components show significant regional change across the continent. Fits based on this harmonic analysis are used to separate the periodic and episodic components of the aerosol time series. An exploratory classification of the aerosol types is undertaken based on (a) the relative periodic amplitudes of the Ångström exponent and aerosol optical depth, (b) the relative amplitudes of the 6- and 4-month harmonic components of the aerosol optical depth, and (c) the ratio of episodic to periodic variation in aerosol optical depth. It is shown that Australian aerosol can be broadly grouped into three classes: tropical, arid and temperate. Statistically significant decadal trends are found at 4 of the 22 stations. Despite the apparently small

  13. Impact of Clouds and Aerosols on Photochemistry During the TexAQS II Radical and Aerosol Measurement Project

    NASA Astrophysics Data System (ADS)

    Flynn, J. H.; Lefer, B. L.; Rappenglueck, B.; Olson, J. R.; Chen, G.

    2007-12-01

    Photochemistry is responsible for the production of tropospheric ozone, the primary component of smog. In 2006, Houston, Texas experienced 20 days with a 1-hour ozone average in excess of 125 ppbv, and 36 days with an 8-hour average over 85 ppbv. Two models were used to assess the impact of clouds and aerosols on the photochemical production and loss of ozone and radicals in a polluted urban environment. The NASA Langley Research Center (LaRC) 0-D photochemical box model was used to assess the changes in the photochemical budgets due to varying cloud and aerosol conditions. The NCAR Tropospheric Ultraviolet and Visible (TUV) radiative transfer model was used to calculate photolysis frequencies for clear sky conditions with a variety of aerosol profiles. These tools were used to analyze the data set collected during the Texas Air Quality Study II Radical and Aerosol Measurement Project (TRAMP) with respect to ozone and radical budgets. Measurements of trace gasses, aerosols, meteorological parameters, and radiation were collected between mid-August and early October 2006 at the University of Houston. The photochemical model was run using various photolysis rates that reflect a range of atmospheric conditions impacting the actinic flux. Rates from real-time actinic flux measurements include the impact of both the clouds and aerosols that are present. Photolysis rates for clear-sky (cloud-free) conditions, both with and without aerosol profiles were calculated using the TUV radiative transfer model. A comparison of the photochemical ozone and radical budgets resulting from these different rates indicate those sensitivities to the presence of aerosols and clouds. Approximately seven of the 50 days during the campaign were cloud-free and were compared to LaRC-TUV results to show the effects of aerosols. The remaining days show the effects of both aerosols and cloud conditions that varied from partly cloudy to heavy overcast conditions. A cloud camera was used to

  14. Stratocumulus cloud height variations determined from surface and satellite observations

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Young, David F.; Davies, R.; Blaskovic, M.; Albrecht, Bruce A.

    1990-01-01

    Determination of cloud-top heights from satellite-inferred cloud-top temperatures is a relatively straightforward procedure for a well-behaved troposphere. The assumption of a monotonically decreasing temperature with increasing altitude is commonly used to assign a height to a given cloud-top temperature. In the hybrid bispectral threshold method, or HBTM, Minnis et al. (1987) assume that the lapse rate for the troposphere is -6.5/Kkm and that the surface temperature which calibrated this lapse rate is the 24 hour mean of the observed or modeled clear-sky, equivalent blackbody temperature. The International Satellite Cloud Climatology Project (ISCCP) algorithm (Rossow et al., 1988) attempts a more realistic assignment of height by utilizing interpolations of analyzed temperature fields from the National Meteorological Center (NMC) to determine the temperature at a given level over the region of interest. Neither these nor other techniques have been tested to any useful extent. The First ISCCP Regional Experiment (FIRE) Intensive Field Observations (IFO) provide an excellent opportunity to assess satellite-derived cloud height results because of the availability of both direct and indirect cloud-top altitude data of known accuracy. The variations of cloud-top altitude during the Marine Stratocumulus IFO (MSIFO, June 29 to July 19, 1987) derived from surface, aircraft, and satellite data are examined.

  15. Cloud retrievals from satellite data using optimal estimation: evaluation and application to ATSR

    NASA Astrophysics Data System (ADS)

    Poulsen, C. A.; Siddans, R.; Thomas, G. E.; Sayer, A. M.; Grainger, R. G.; Campmany, E.; Dean, S. M.; Arnold, C.; Watts, P. D.

    2012-08-01

    Clouds play an important role in balancing the Earth's radiation budget. Hence, it is vital that cloud climatologies are produced that quantify cloud macro and micro physical parameters and the associated uncertainty. In this paper, we present an algorithm ORAC (Oxford-RAL retrieval of Aerosol and Cloud) which is based on fitting a physically consistent cloud model to satellite observations simultaneously from the visible to the mid-infrared, thereby ensuring that the resulting cloud properties provide both a good representation of the short-wave and long-wave radiative effects of the observed cloud. The advantages of the optimal estimation method are that it enables rigorous error propagation and the inclusion of all measurements and any a priori information and associated errors in a rigorous mathematical framework. The algorithm provides a measure of the consistency between retrieval representation of cloud and satellite radiances. The cloud parameters retrieved are the cloud top pressure, cloud optical depth, cloud effective radius, cloud fraction and cloud phase. The algorithm can be applied to most visible/infrared satellite instruments. In this paper, we demonstrate the applicability to the Along-Track Scanning Radiometers ATSR-2 and AATSR. Examples of applying the algorithm to ATSR-2 flight data are presented and the sensitivity of the retrievals assessed, in particular the algorithm is evaluated for a number of simulated single-layer and multi-layer conditions. The algorithm was found to perform well for single-layer cloud except when the cloud was very thin; i.e., less than 1 optical depths. For the multi-layer cloud, the algorithm was robust except when the upper ice cloud layer is less than five optical depths. In these cases the retrieved cloud top pressure and cloud effective radius become a weighted average of the 2 layers. The sum of optical depth of multi-layer cloud is retrieved well until the cloud becomes thick, greater than 50 optical depths

  16. Global Weather States and Their Properties from Passive and Active Satellite Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Tselioudis, George; Rossow, William; Zhang, Yuanchong; Konsta, Dimitra

    2013-01-01

    In this study, the authors apply a clustering algorithm to International Satellite Cloud Climatology Project (ISCCP) cloud optical thickness-cloud top pressure histograms in order to derive weather states (WSs) for the global domain. The cloud property distribution within each WS is examined and the geographical variability of each WS is mapped. Once the global WSs are derived, a combination of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical cloud structure retrievals is used to derive the vertical distribution of the cloud field within each WS. Finally, the dynamic environment and the radiative signature of the WSs are derived and their variability is examined. The cluster analysis produces a comprehensive description of global atmospheric conditions through the derivation of 11 WSs, each representing a distinct cloud structure characterized by the horizontal distribution of cloud optical depth and cloud top pressure. Matching those distinct WSs with cloud vertical profiles derived from CloudSat and CALIPSO retrievals shows that the ISCCP WSs exhibit unique distributions of vertical layering that correspond well to the horizontal structure of cloud properties. Matching the derived WSs with vertical velocity measurements shows a normal progression in dynamic regime when moving from the most convective to the least convective WS. Time trend analysis of the WSs shows a sharp increase of the fair-weather WS in the 1990s and a flattening of that increase in the 2000s. The fact that the fair-weather WS is the one with the lowest cloud radiative cooling capability implies that this behavior has contributed excess radiative warming to the global radiative budget during the 1990s.

  17. Major Characteristics of Southern Ocean Cloud Regimes and Their Effects on the Energy Budget

    NASA Technical Reports Server (NTRS)

    Haynes, John M.; Jakob, Christian; Rossow, William B.; Tselioudis, George; Brown, Josephine

    2011-01-01

    Clouds over the Southern Ocean are often poorly represented by climate models, but they make a significant contribution to the top-of-atmosphere (TOA) radiation balance, particularly in the shortwave portion of the energy spectrum. This study seeks to better quantify the organization and structure of Southern Hemisphere midlatitude clouds by combining measurements from active and passive satellite-based datasets. Geostationary and polar-orbiter satellite data from the International Satellite Cloud Climatology Project (ISCCP) are used to quantify large-scale, recurring modes of cloudiness, and active observations from CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to examine vertical structure, radiative heating rates, and precipitation associated with these clouds. It is found that cloud systems are organized into eight distinct regimes and that ISCCP overestimates the midlevel cloudiness of these regimes. All regimes contain a relatively high occurrence of low cloud, with 79%of all cloud layers observed having tops below 3 km, but multiple-layered clouds systems are present in approximately 34% of observed cloud profiles. The spatial distribution of regimes varies according to season, with cloud systems being geometrically thicker, on average, during the austral winter. Those regimes found to be most closely associated with midlatitude cyclones produce precipitation the most frequently, although drizzle is extremely common in low-cloud regimes. The regimes associated with cyclones have the highest in-regime shortwave cloud radiative effect at the TOA, but the low-cloud regimes, by virtue of their high frequency of occurrence over the oceans, dominate both TOA and surface shortwave effects in this region as a whole.

  18. Major Characteristics of Southern Ocean Cloud Regimes and Their Effects on the Energy Budget

    NASA Technical Reports Server (NTRS)

    Haynes, John M.; Jakob, Christian; Rossow, William B.; Tselioudis, George; Brown, Josephine

    2011-01-01

    Clouds over the Southern Ocean are often poorly represented by climate models, but they make a significant contribution to the top-of-atmosphere (TOA) radiation balance, particularly in the shortwave portion of the energy spectrum. This study seeks to better quantify the organization and structure of Southern Hemisphere midlatitude clouds by combining measurements from active and passive satellite-based datasets. Geostationary and polar-orbiter satellite data from the International Satellite Cloud Climatology Project (ISCCP) are used to quantify large-scale, recurring modes of cloudiness, and active observations from CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to examine vertical structure, radiative heating rates, and precipitation associated with these clouds. It is found that cloud systems are organized into eight distinct regimes and that ISCCP overestimates the midlevel cloudiness of these regimes. All regimes contain a relatively high occurrence of low cloud, with 79%of all cloud layers observed having tops below 3 km, but multiple-layered clouds systems are present in approximately 34% of observed cloud profiles. The spatial distribution of regimes varies according to season, with cloud systems being geometrically thicker, on average, during the austral winter. Those regimes found to be most closely associated with midlatitude cyclones produce precipitation the most frequently, although drizzle is extremely common in low-cloud regimes. The regimes associated with cyclones have the highest in-regime shortwave cloud radiative effect at the TOA, but the low-cloud regimes, by virtue of their high frequency of occurrence over the oceans, dominate both TOA and surface shortwave effects in this region as a whole.

  19. Intercomparison of CALIOP Cloud and Aerosol Profiles with in situ Marine Stratocumulus Observations during ORACLES

    NASA Astrophysics Data System (ADS)

    Heikkila, A.; Small Griswold, J. D.

    2016-12-01

    The purpose of the ORACLES ( ObseRvations of Aerosols above CLouds and their intEractionS) field campaign that occurred during the months of August and September 2016 off the coast of Namibia is to measure the interactions of biomass burning aerosols (BBA) and clouds. In this region stratocumulus clouds are the dominant cloud type and are a critical component of Earth's radiation budget due to their high albedo and resulting cooling effect. They also impact the hydrological cycle through drizzle production. BBA are the predominant aerosol type in this region and also play multiple roles by modifying the atmospheric temperature structure through absorbing solar radiation and altering cloud properties by serving as CCN. These processes of aerosol-cloud interactions are poorly understood, thus the use of multiple measurement techniques, including space-borne remotely sensed data and in situ measurements, offer a more in depth look into these interactions. To address this complex system we combine satellite data from CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) and in situ data from the FPDR-PDI. CALIOP Level 2 Lidar Vertical Feature Mask (VFM) data was collected and analyzed for the years 2006-2015 to establish a climatological profile for aerosol and clouds in the region. Individual swaths observed during the 2016 field project are used to compare with in situ measurements. The VFM data provides aerosol and cloud types in categories based on their optical properties, along with their vertical structures in the atmosphere. To determine actual microphysical cloud properties we use a FPDR-PDI to measure instantaneous cloud drop size, cloud drop concentration, drop size distributions and liquid water content. This work compares average CALIOP aerosol and cloud profiles across the ORACLES region, including the stratocumulus to cumulus transition, with the in situ FPDR-PDI data to confirm cloud altitude and thickness and cloud-aerosol collocation.

  20. Molecular characterisation of secondary organic aerosol formed during cloud condensation-evaporation cycles from isoprene and methacrolein photooxidation (CUMULUS project)

    NASA Astrophysics Data System (ADS)

    Giorio, C.; Monod, A.; Bregonzio-Rozier, L.; Siekmann, F.; Cazaunau, M.; Termine-Roussel, B.; DeWitt, H. L.; Gratien, A.; Michoud, V.; Pangui, E.; Ravier, S.; Tapparo, A.; Vermeylen, R.; Claeys, M.; Voisin, D.; Salque-Moreton, G.; Kalberer, M.; Doussin, J. F.

    2016-12-01

    Biogenic volatile organic compounds (BVOCs) undergo many reactions in the atmosphere and form a wide range of oxidised and water-soluble compounds. These compounds could partition into atmospheric water droplets, and react within the aqueous phase producing higher molecular weight and less volatile compounds which could remain in the particle phase after water evaporation (Ervens et al., 2011). The aim of this work is the characterisation of secondary organic aerosol (SOA) formed from the photooxidation of isoprene and methacrolein. The experiments were performed within the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere), at the 4.2 m3stainless steel CESAM chamber at LISA (Brégonzio-Rozier et al., 2016). In each experiment, isoprene or methacrolein was photooxidised with HONO and clouds have been produced to study oxidation processes in a multiphase (gas-particles-clouds) environment. Particular attention has been focused on SOA formation and aging during cloud condensation-evaporation cycles and a range of different on-line and off-line mass spectrometry techniques have been used to obtain a detailed characterisation of SOA at molecular level in dry conditions, during cloud events and after cloud evaporation. We observed a large number of long homologous series of oligomers in all experiments, together with a complex co-oligomerised system made of monomers with a large variety of different structures. Comparison of SOA from multiphasic (smog chamber) experiments and samples from aqueous phase oxidation of methacrolein with ·OH radical pointed out different types of oligomerisation reactions dominating the two different systems. Ervens et al. (2011) Atmos. Chem. Phys. 11, 11069-11102. Brégonzio-Rozier et al. (2016) Atmos. Chem. Phys. 16, 1747-1760.

  1. Longwave cloud radiative forcing at the surface from ISCCP-C1 data

    NASA Technical Reports Server (NTRS)

    Gupta, Shashi K.; Ritchey, Nancy A.; Wilber, Anne C.; Darnell, Wayne L.

    1990-01-01

    A method for deriving one component of the total cloud forcing picture, namely, the LW cloud forcing at the surface, is presented. The method is based on a validated radiative transfer technique and utilizes meteorological data available from the International Satellite Cloud Climatology Project. The radiative transfer model used was validated earlier and the TOVS-derived temperature and water vapor data used were generally reasonable. On a monthly-average basis, random error was estimated to be in the 5-10 W/sq m range, but biases as large as 10-20 W/sq m can occur in some regions. The lack of information on cloud-base heights were found to be the largest source of errors in the models and the meteorological data.

  2. Climatology of urban regional systems

    NASA Technical Reports Server (NTRS)

    Pease, R. W.

    1970-01-01

    The combining of remote sensing technologies to urban-regional energy climatology is studied. It was found to be three dimensional with a mosaic urban surface, each smaller surface with its own radiant and thermal properties. Urban patterns of radiant exchange were found to be constantly changing during diurnal and annual cycles. Results were derived from Barbados data using remote methods for monitoring and mapping radiation. Isoline maps of terrestrial radiation patterns were made generalizing the minute patterns of the scan image.

  3. The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6

    NASA Astrophysics Data System (ADS)

    Webb, Mark J.; Andrews, Timothy; Bodas-Salcedo, Alejandro; Bony, Sandrine; Bretherton, Christopher S.; Chadwick, Robin; Chepfer, Hélène; Douville, Hervé; Good, Peter; Kay, Jennifer E.; Klein, Stephen A.; Marchand, Roger; Medeiros, Brian; Pier Siebesma, A.; Skinner, Christopher B.; Stevens, Bjorn; Tselioudis, George; Tsushima, Yoko; Watanabe, Masahiro

    2017-01-01

    The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud-climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions How does the Earth system respond to forcing? and What are the origins and consequences of systematic model biases? and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity.A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in

  4. The MJO Transition from Shallow to Deep Convection in CloudSat/CALIPSO Data and GISS GCM Simulations

    NASA Technical Reports Server (NTRS)

    DelGenio, Anthony G.; Chen, Yonghua; Kim, Daehyun; Yao, Mao-Sung

    2013-01-01

    The relationship between convective penetration depth and tropospheric humidity is central to recent theories of the Madden-Julian oscillation (MJO). It has been suggested that general circulation models (GCMs) poorly simulate the MJO because they fail to gradually moisten the troposphere by shallow convection and simulate a slow transition to deep convection. CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are analyzed to document the variability of convection depth and its relation to water vapor during the MJO transition from shallow to deep convection and to constrain GCM cumulus parameterizations. Composites of cloud occurrence for 10MJO events show the following anticipatedMJO cloud structure: shallow and congestus clouds in advance of the peak, deep clouds near the peak, and upper-level anvils after the peak. Cirrus clouds are also frequent in advance of the peak. The Advanced Microwave Scanning Radiometer for EarthObserving System (EOS) (AMSR-E) columnwater vapor (CWV) increases by;5 mmduring the shallow- deep transition phase, consistent with the idea of moisture preconditioning. Echo-top height of clouds rooted in the boundary layer increases sharply with CWV, with large variability in depth when CWV is between;46 and 68 mm. International Satellite Cloud Climatology Project cloud classifications reproduce these climatological relationships but correctly identify congestus-dominated scenes only about half the time. A version of the Goddard Institute for Space Studies Model E2 (GISS-E2) GCM with strengthened entrainment and rain evaporation that produces MJO-like variability also reproduces the shallow-deep convection transition, including the large variability of cloud-top height at intermediate CWV values. The variability is due to small grid-scale relative humidity and lapse rate anomalies for similar values of CWV. 1.

  5. External Influences on Modeled and Observed Cloud Trends

    NASA Technical Reports Server (NTRS)

    Marvel, Kate; Zelinka, Mark; Klein, Stephen A.; Bonfils, Celine; Caldwell, Peter; Doutriaux, Charles; Santer, Benjamin D.; Taylor, Karl E.

    2015-01-01

    Understanding the cloud response to external forcing is a major challenge for climate science. This crucial goal is complicated by intermodel differences in simulating present and future cloud cover and by observational uncertainty. This is the first formal detection and attribution study of cloud changes over the satellite era. Presented herein are CMIP5 (Coupled Model Intercomparison Project - Phase 5) model-derived fingerprints of externally forced changes to three cloud properties: the latitudes at which the zonally averaged total cloud fraction (CLT) is maximized or minimized, the zonal average CLT at these latitudes, and the height of high clouds at these latitudes. By considering simultaneous changes in all three properties, the authors define a coherent multivariate fingerprint of cloud response to external forcing and use models from phase 5 of CMIP (CMIP5) to calculate the average time to detect these changes. It is found that given perfect satellite cloud observations beginning in 1983, the models indicate that a detectable multivariate signal should have already emerged. A search is then made for signals of external forcing in two observational datasets: ISCCP (International Satellite Cloud Climatology Project) and PATMOS-x (Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Atmospheres - Extended). The datasets are both found to show a poleward migration of the zonal CLT pattern that is incompatible with forced CMIP5 models. Nevertheless, a detectable multivariate signal is predicted by models over the PATMOS-x time period and is indeed present in the dataset. Despite persistent observational uncertainties, these results present a strong case for continued efforts to improve these existing satellite observations, in addition to planning for new missions.

  6. External Influences on Modeled and Observed Cloud Trends

    NASA Technical Reports Server (NTRS)

    Marvel, Kate; Zelinka, Mark; Klein, Stephen A.; Bonfils, Celine; Caldwell, Peter; Doutriaux, Charles; Santer, Benjamin D.; Taylor, Karl E.

    2015-01-01

    Understanding the cloud response to external forcing is a major challenge for climate science. This crucial goal is complicated by intermodel differences in simulating present and future cloud cover and by observational uncertainty. This is the first formal detection and attribution study of cloud changes over the satellite era. Presented herein are CMIP5 (Coupled Model Intercomparison Project - Phase 5) model-derived fingerprints of externally forced changes to three cloud properties: the latitudes at which the zonally averaged total cloud fraction (CLT) is maximized or minimized, the zonal average CLT at these latitudes, and the height of high clouds at these latitudes. By considering simultaneous changes in all three properties, the authors define a coherent multivariate fingerprint of cloud response to external forcing and use models from phase 5 of CMIP (CMIP5) to calculate the average time to detect these changes. It is found that given perfect satellite cloud observations beginning in 1983, the models indicate that a detectable multivariate signal should have already emerged. A search is then made for signals of external forcing in two observational datasets: ISCCP (International Satellite Cloud Climatology Project) and PATMOS-x (Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Atmospheres - Extended). The datasets are both found to show a poleward migration of the zonal CLT pattern that is incompatible with forced CMIP5 models. Nevertheless, a detectable multivariate signal is predicted by models over the PATMOS-x time period and is indeed present in the dataset. Despite persistent observational uncertainties, these results present a strong case for continued efforts to improve these existing satellite observations, in addition to planning for new missions.

  7. Arctic aerosol and cloud measurements in the frame of the Ice-Atmosphere-Ocean Observing System (IAOOS) project

    NASA Astrophysics Data System (ADS)

    Pelon, J.; Mariage, V.; Blouzon, F.; Geyskens, N.; Victori, S.; Amarouche, N.; Drezen, C.; Guillot, A.; Calzas, M.; Garracio, M.; Desautez, A.; Pascal, N.; Raut, J. C.; Sennechael, N.; Provost, C.

    2015-12-01

    In the frame of the French IAOOS Equipex project, a new observational network is to be developed for the ocean-ice-atmosphere survey over the Arctic starting in 2015 to better understand interactions and in particular the role of aerosols and clouds in the Arctic. Eye-safe lidar measurements will allow to profile aerosols and clouds for the atmospheric part, with the objective to perform regular measurements and characterize their vertical structure and optical properties complementing satellite observations. Radiation and meteorological parameters will simultaneously be measured at the surface. A first buoy has been prototyped and deployed in April 2014 at the Barneo site set by the Russian teams at the North Pole. Measurements with the first autonomous backscatter lidar ever deployed in the arctic have been taken from April to end of November 2014 before the buoy was lost. A second set of data were acquired during the N-ICE campaign north of Svalbard during winter 2015. Up to four profiles a day (10 mn sequence each) have been performed allowing a good sampling with respect to meteorological analyses. Observations have shown that the occurrence of low level clouds was higher than 90% during summer. New deployments are planned in summer 2015 as the start of the IAOOS network. The project is presented, instruments are described and first results are discussed.

  8. Global Single and Multiple Cloud Classification with a Fuzzy Logic Expert System

    NASA Technical Reports Server (NTRS)

    Welch, Ronald M.; Tovinkere, Vasanth; Titlow, James; Baum, Bryan A.

    1996-01-01

    An unresolved problem in remote sensing concerns the analysis of satellite imagery containing both single and multiple cloud layers. While cloud parameterizations are very important both in global climate models and in studies of the Earth's radiation budget, most cloud retrieval schemes, such as the bispectral method used by the International Satellite Cloud Climatology Project (ISCCP), have no way of determining whether overlapping cloud layers exist in any group of satellite pixels. Coakley (1983) used a spatial coherence method to determine whether a region contained more than one cloud layer. Baum et al. (1995) developed a scheme for detection and analysis of daytime multiple cloud layers using merged AVHRR (Advanced Very High Resolution Radiometer) and HIRS (High-resolution Infrared Radiometer Sounder) data collected during the First ISCCP Regional Experiment (FIRE) Cirrus 2 field campaign. Baum et al. (1995) explored the use of a cloud classification technique based on AVHRR data. This study examines the feasibility of applying the cloud classifier to global satellite imagery.

  9. Lidar measurements of boundary layers, aerosol scattering and clouds during project FIFE

    NASA Technical Reports Server (NTRS)

    Eloranta, Edwin W. (Principal Investigator)

    1995-01-01

    A detailed account of progress achieved under this grant funding is contained in five journal papers. The titles of these papers are: The calculation of area-averaged vertical profiles of the horizontal wind velocity using volume imaging lidar data; Volume imaging lidar observation of the convective structure surrounding the flight path of an instrumented aircraft; Convective boundary layer mean depths, cloud base altitudes, cloud top altitudes, cloud coverages, and cloud shadows obtained from Volume Imaging Lidar data; An accuracy analysis of the wind profiles calculated from Volume Imaging Lidar data; and Calculation of divergence and vertical motion from volume-imaging lidar data. Copies of these papers form the body of this report.

  10. The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6

    DOE PAGES

    Webb, Mark J.; Andrews, Timothy; Bodas-Salcedo, Alejandro; ...

    2017-01-01

    Our primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud–climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. But, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questionsmore » How does the Earth system respond to forcing? and What are the origins and consequences of systematic model biases? and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity.A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in

  11. The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6

    SciTech Connect

    Webb, Mark J.; Andrews, Timothy; Bodas-Salcedo, Alejandro; Bony, Sandrine; Bretherton, Christopher S.; Chadwick, Robin; Chepfer, Hélène; Douville, Hervé; Good, Peter; Kay, Jennifer E.; Klein, Stephen A.; Marchand, Roger; Medeiros, Brian; Siebesma, A. Pier; Skinner, Christopher B.; Stevens, Bjorn; Tselioudis, George; Tsushima, Yoko; Watanabe, Masahiro

    2017-01-01

    Our primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud–climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. But, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions How does the Earth system respond to forcing? and What are the origins and consequences of systematic model biases? and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity.

    A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do

  12. NASA/GEWEX shortwave surface radiation budget: Integrated data product with reprocessed radiance, cloud, and meteorology inputs, and new surface albedo treatment

    NASA Astrophysics Data System (ADS)

    Cox, Stephen J.; Stackhouse, Paul W.; Gupta, Shashi K.; Mikovitz, J. Colleen; Zhang, Taiping

    2017-02-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. Spatial resolution is 1 degree. The current Release 3.0 (available at gewex-srb.larc.nasa.gov) uses the International Satellite Cloud Climatology Project (ISCCP) DX product for pixel level radiance and cloud information. This product is subsampled to 30 km. ISCCP is currently recalibrating and recomputing their entire data series, to be released as the H product, at 10km resolution. The ninefold increase in pixel number will allow SRB a higher resolution gridded product (e.g. 0.5 degree), as well as the production of pixel-level fluxes. Other key input improvements include a detailed aerosol history using the Max Planck Institute Aerosol Climatology (MAC), and temperature and moisture profiles from nnHIRS.

  13. A Comparison of Multiscale Variations of Decade-long Cloud Fractions from Six Different Platforms over the Southern Great Plains in the United States

    SciTech Connect

    Wu, Wei; Liu, Yangang; Jensen, Michael; Toto, Tami; Foster, Michael J.; Long, Charles N.

    2014-03-27

    This study investigates 1997-2011 observationally based cloud fraction estimates from different platforms over the Southern Great Plains, United States, including three ground-based estimates and three satellite-based estimates at multiple temporal and spatial scales. They are: 1) the Active Remotely Sensed Clouds Locations (ARSCL); 2) the Total Sky Imager (TSI); 3) the Radiative Flux Analysis (RFA); 4) Geostationary Operational Environmental Satellite (GOES); 5) the International Satellite Cloud Climatology Project (ISCCP); and 6) Advanced Very High Resolution Radiometer Pathfinder Atmospheres Extended (PATMOS-x). A substantial disagreement is evident among different estimates, especially for ISCCP and ARSCL with statistically significant larger cloud fractions than the other estimates. For example, ISCCP and ARSCL mean cloud fractions in January are ~21% and 8% larger than the average from all the other estimates, respectively. Three estimates (ISCCP, ARSCL, GOES) exhibit an 8%-10% overall increase in the annually averaged cloud fractions from 1998 to 2009; the other three estimates (TSI, RFA, and PATMOS-x) exhibit no significant tendency of increase in this decade. Monthly cloud fractions from all the estimates exhibit Gaussian-like distributions while the distributions of daily cloud fractions are dependent on spatial scales. Investigations of high-resolution cloud fractions reveal that the differences stem from the inconsistent definitions of cloud fraction. Findings from this study suggest caution when using observationally based cloud fraction estimates for climate studies, highlighting that the consistency in defining cloud fraction between models and observations is crucial for studying the Earth’s climate.

  14. Cirrus cloud retrieval using infrared sounding data: Multilevel cloud errors

    NASA Technical Reports Server (NTRS)

    Baum, Bryan A.; Wielicki, Bruce A.

    1994-01-01

    In this study we perform an error analysis for cloud-top pressure retrieval using the High-Resolution Infrared Radiometric Sounder (HIRS/2) 15-microns CO2 channels for the two-layer case of transmissive cirrus overlying an overcast, opaque stratiform cloud. This analysis includes standard deviation and bias error due to instrument noise and the presence of two cloud layers, the lower of which is opaque. Instantaneous cloud pressure retrieval errors are determined for a range of cloud amounts (0.1-1.0) and cloud-top pressures (850-250 mb). Large cloud-top pressure retrieval errors are found to occur when a lower opaque layer is present underneath an upper transmissive cloud layer in the satellite field of view (FOV). Errors tend to increase with decreasing upper-cloud effective cloud amount and with decreasing cloud height (increasing pressure). Errors in retrieved upper-cloud pressure result in corresponding errors in derived effective cloud amount. For the case in which a HIRS FOV has two distinct cloud layers, the difference between the retrieved and actual cloud-top pressure is positive in all cases, meaning that the retrieved upper-cloud height is lower than the actual upper-cloud height. In addition, errors in retrieved cloud pressure are found to depend upon the lapse rate between the low-level cloud top and the surface. We examined which sounder channel combinations would minimize the total errors in derived cirrus cloud height caused by instrument noise and by the presence of a lower-level cloud. We find that while the sounding channels that peak between 700 and 1000 mb minimize random errors, the sounding channels that peak at 300-500 mb minimize bias errors. For a cloud climatology, the bias errors are most critical.

  15. Advancing cloud lifecycle representation in numerical models using innovative analysis methods that bridge arm observations over a breadth of scales

    SciTech Connect

    Tselioudis, George

    2016-03-04

    From its location on the subtropics-midlatitude boundary, the Azores is influenced by both the subtropical high pressure and the midlatitude baroclinic storm regimes, and therefore experiences a wide range of cloud structures, from fair-weather scenes to stratocumulus sheets to deep convective systems. This project combined three types of data sets to study cloud variability in the Azores: a satellite analysis of cloud regimes, a reanalysis characterization of storminess, and a 19-month field campaign that occurred on Graciosa Island. Combined analysis of the three data sets provides a detailed picture of cloud variability and the respective dynamic influences, with emphasis on low clouds that constitute a major uncertainty source in climate model simulations. The satellite cloud regime analysis shows that the Azores cloud distribution is similar to the mean global distribution and can therefore be used to evaluate cloud simulation in global models. Regime analysis of low clouds shows that stratocumulus decks occur under the influence of the Azores high-pressure system, while shallow cumulus clouds are sustained by cold-air outbreaks, as revealed by their preference for post-frontal environments and northwesterly flows. An evaluation of CMIP5 climate model cloud regimes over the Azores shows that all models severely underpredict shallow cumulus clouds, while most models also underpredict the occurrence of stratocumulus cloud decks. It is demonstrated that carefully selected case studies can be related through regime analysis to climatological cloud distributions, and a methodology is suggested utilizing process-resolving model simulations of individual cases to better understand cloud-dynamics interactions and attempt to explain and correct climate model cloud deficiencies.

  16. Annual Climatology of the Diurnal Cycle on the Canadian Prairies

    NASA Astrophysics Data System (ADS)

    Betts, Alan; Tawfik, Ahmed

    2016-01-01

    We show the annual climatology of the diurnal cycle, stratified by opaque cloud, using the full hourly resolution of the Canadian Prairie data. The opaque cloud field itself has distinct cold and warm season diurnal climatologies; with a near-sunrise peak of cloud in the cold season and an early afternoon peak in the warm season. There are two primary climate states on the Canadian Prairies, separated by the freezing point of water, because a reflective surface snow cover acts as a climate switch. Both cold and warm season climatologies can be seen in the transition months of November, March and April with a large difference in mean temperature. In the cold season with snow, the diurnal ranges of temperature and relative humidity increase quasi-linearly with decreasing cloud, and increase from December to March with increased solar forcing. The warm season months, April to September, show a homogeneous coupling to the cloud cover, and a diurnal cycle of temperature and humidity that depends only on net longwave. Our improved representation of the diurnal cycle shows that the warm season coupling between diurnal temperature range and net longwave is weakly quadratic through the origin, rather than the linear coupling shown in earlier papers. We calculate the conceptually important 24-h imbalances of temperature and relative humidity (and other thermodynamic variables) as a function of opaque cloud cover. In the warm season under nearly clear skies, there is a warming of +2oC and a drying of -6% over the 24-h cycle, which is about 12% of their diurnal ranges. We summarize results on conserved variable diagrams and explore the impact of surface windspeed on the diurnal cycle in the cold and warm seasons. In all months, the fall in minimum temperature is reduced with increasing windspeed, which reduces the diurnal temperature range. In July and August, there is an increase of afternoon maximum temperature and humidity at low windspeeds, and a corresponding rise in

  17. Cloud information for FIRE from surface weather reports

    NASA Technical Reports Server (NTRS)

    Hahn, Carole J.; Warren, Stephen G.; London, Julius

    1990-01-01

    Surface weather observations of clouds were analyzed to obtain a global cloud climatology (Warren et al, 1986; 1988). The form of the synoptic weather code limits the types of cloud information which are available from these reports. Comparison of surface weather reports with instrumental observations during the FIRE field experiments can help to clarify the operational definitions which were made in the climatology because of the nature of the synoptic code. The long-term climatology from surface weather observations is also useful background for planning the location and timing of intensive field experiments.

  18. Cloud Water Path Variation with Temperature over China

    NASA Astrophysics Data System (ADS)

    Li, X.; Guo, X.; Zhu, J.

    2009-12-01

    Cloud feedback has been one of the most concerned topics in climate change research. The insufficient understanding of cloud feedbacks is a major source of uncertainty in GCM simulations. With satellite cloud property data and reanalysis data, quantitative understanding of cloud feedback becomes possible. In this research, cloud water path (CWP) variation with temperature (Ta) is investigated and the research area locates in China. CWP, cloud top temperature (CTT) and cloud top pressure (CTP) data are from ISCCP (International Satellite Cloud Climatology Project). Ta data are from ERA-40. Data are collected from 1984 to 2001. According to regional climatic features, the analyses are carried out in five different areas. We use the same method, which was used by Tselioudis to analyze the relation between cloud optical thickness and temperature, to calculate the Logarithmic derivative of CWP with temperature. CWP is sampled from clouds with tops in the 680-800 mb range and Ta is the mean temperature of the 680-800 mb. According to the analysis over China, to the south of 35°N, CWP increased with Ta. But to the north of 35°N, CWP decreases with Ta in the temperature interval of 263-273K and increases with Ta in the other temperature intervals in the Northeastern China. The CWP decreases with Ta in the Northwestern China. The different seasonal patterns of CWP variation with temperature are also found. In the Northwestern China, CWP decreases with Ta in different seasons. In the Northeastern China, CWP decreases with Ta in spring and fall. CWP increases with Ta in the Southeastern China except summer. In the Southwestern China, CWP decreased with Ta in summer and fall. In the Tibetan Plateau CWP increased with Ta excluding winter.

  19. Sprite Climatology in the Eastern Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Yair, Yoav; Price, Colin; Katzenelson, Dor; Rosenthal, Neta; Rubanenko, Lior; Ben-Ami, Yuval; Arnone, Enrico

    2015-04-01

    We present statistical analysis of 436 sprites observed in 7 winter campaigns from 2006/7-2012/13. Results show a clear peak in the frequency of sprite detections, with maximum values (< 40% of events) between 00:30-02:15 LST (22:30-00:15 UT; LST=UT+2). The detection times of sprites are well-correlated with a relative increase in the fraction of +CG strokes, which exhibit maxima between 00:00-02:00 LST. The morphological distribution of 339 sprites, that we were able to clearly identify, is dominated by column sprites (49.3%), with angels (33.0%) and carrots (25.7%) being less frequent. This is similar to reports of winter sprites over the Sea of Japan and summer ones in central Europe. Other shapes such as trees, wishbones, etc. appear quite rarely. Single element events constitute 16.5% of observations, with 83.5% containing 2 elements or more. Clusters of homogeneous types are slightly more frequent than mixed ones (55%). Our observations suggest winter East Mediterranean thunderstorms to have a vertical structure that is an intermediate type between high tropical convective systems and the lower cloud-top cells in winter thunderstorms over the Sea of Japan. The climatology shows that the Eastern Mediterranean is a major sprite producer during Northern Hemisphere winter, and thus the existing and future optical observation infrastructure in Israel offers ground-based coverage for upcoming space missions that aim to map global sprite activity.

  20. Sprite climatology in the Eastern Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Yair, Yoav; Price, Colin; Katzenelson, Dor; Rosenthal, Neta; Rubanenko, Lior; Ben-Ami, Yuval; Arnone, Enrico

    2015-04-01

    We present statistical analysis of 436 sprites observed in 7 winter campaigns from 2006/7-2012/13. Results show a clear peak in the frequency of sprite detections, with maximum values (< 40% of events) between 00:30 and 02:15 LST (22:30-00:15 UT; LST = UT + 2). The detection times of sprites are well-correlated with a relative increase in the fraction of + CG strokes, which exhibit maxima between 00:00 and 02:00 LST. The morphological distribution of 339 sprites, that we were able to clearly identify, is dominated by column sprites (49.3%), with angels (33.0%) and carrots (25.7%) being less frequent. This is similar to reports of winter sprites over the Sea of Japan and summer ones in Central Europe. Other shapes such as trees, wishbones, etc. appear quite rarely. Single element events constitute 16.5% of observations, with 83.5% containing 2 elements or more. Clusters of homogenous types are slightly more frequent than mixed ones (55%). Our observations suggest winter Mediterranean thunderstorms to have a vertical structure in between high tropical convective systems and the lower cloud-top cells in Japan. The climatology shows the Eastern Mediterranean to be a major sprite producer in Northern Hemisphere winter, and offers ground-based coverage for future space missions.

  1. The observed sensitivity of high clouds to mean surface temperature anomalies in the tropics

    NASA Astrophysics Data System (ADS)

    Zelinka, Mark D.; Hartmann, Dennis L.

    2011-12-01

    Cloud feedback represents the source of largest diversity in projections of future warming. Observational constraints on both the sign and magnitude of the feedback are limited, since it is unclear how the natural variability that can be observed is related to secular climate change, and analyses have rarely been focused on testable physical theories for how clouds should respond to climate change. In this study we use observations from a suite of satellite instruments to assess the sensitivity of tropical high clouds to interannual tropical mean surface temperature anomalies. We relate cloud changes to a physical governing mechanism that is sensitive to the vertical structure of warming. Specifically, we demonstrate that the mean and interannual variability in both the altitude and fractional coverage of tropical high clouds as measured by CloudSat, the Moderate Resolution Imaging Spectroradiometer, the Atmospheric Infrared Sounder, and the International Satellite Cloud Climatology Project are well diagnosed by upper tropospheric convergence computed from the mass and energy budget of the clear-sky atmosphere. Observed high clouds rise approximately isothermally in accordance with theory and exhibit an overall reduction in coverage when the tropics warms, similar to their behavior in global warming simulations. Such cloud changes cause absorbed solar radiation to increase more than does outgoing longwave radiation, resulting in a positive but statistically insignificant net high cloud feedback in response to El Niño-Southern Oscillation. The results suggest that the convergence metric based on simple mass and energy budget constraints may be a powerful tool for understanding observed and modeled high cloud behavior and for evaluating the realism of modeled high cloud changes in response to a variety of forcings.

  2. Satellite-Based Assessment of Possible Dust Aerosols Semi-Direct Effect on Cloud Water Path over East Asia

    NASA Technical Reports Server (NTRS)

    Huang, Jianping; Lin, Bing; Minnis, Patrick; Wang, Tainhe; Wang, Xin; Hu, Yongxiang; Yi, Yuhong; Ayers, J. Kirk

    2006-01-01

    The semi-direct effects of dust aerosols are analyzed over eastern Asia using 2 years (June 2002 to June 2004) of data from the Clouds and the Earth s Radiant Energy System (CERES) scanning radiometer and MODerate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, and 18 years (1984 to 2001) of International Satellite Cloud Climatology Project (ISCCP) data. The results show that the water path of dust-contaminated clouds is considerably smaller than that of dust-free clouds. The mean ice water path (IWP) and liquid water path (LWP) of dusty clouds are less than their dust-free counterparts by 23.7% and 49.8%, respectively. The long-term statistical relationship derived from ISCCP also confirms that there is significant negative correlation between dust storm index and ISCCP cloud water path. These results suggest that dust aerosols warm clouds, increase the evaporation of cloud droplets and further reduce cloud water path, the so-called semi-direct effect. The semi-direct effect may play a role in cloud development over arid and semi-arid areas of East Asia and contribute to the reduction of precipitation.

  3. Mars Orbiter Camera climatology of textured dust storms

    NASA Astrophysics Data System (ADS)

    Guzewich, Scott D.; Toigo, Anthony D.; Kulowski, Laura; Wang, Huiqun

    2015-09-01

    We report the climatology of "textured dust storms", those dust storms that have visible structure on their cloud tops that are indicative of active dust lifting, as observed in Mars Daily Global Maps produced from Mars Orbiter Camera wide-angle images. Textured dust storms predominantly occur in the equinox seasons while both solstice periods experience a planet-wide "pause" in textured dust storm activity. These pauses correspond to concurrent decreases in global atmospheric dust opacity. Textured dust storms most frequently occur in Acidalia Planitia, Chryse Planitia, Arcadia Planitia, and Hellas basin. To examine the nature of the link between textured dust storms and atmospheric dust opacity, we compare the textured dust storm climatology with a record of atmospheric dust opacity and find a peak global correlation coefficient of approximately 0.5 with a lag of 20-40° in solar longitude in the opacity compared to the solar climatology. This implies that textured dust storms observed at 1400 local time by MOC are responsible for a large fraction of atmospheric dust opacity and that other mechanisms (e.g., dust devil lifting or storm-scale lifting not observed in this study) may supply a comparable amount of dust.

  4. Cloud Modeling Using Field Project Data for the Study of Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Shie, C.-H.; Lang, S.; Simpson, J.

    2003-01-01

    The use of cloud-resolving models (CRMs) in the study of precipitation process and their relation to the large-scale environment can be generally categorized into two approaches. The first approach is so called "cloud ensemble modeling". In this approach, many clouds of different size in various stages of their lifecycles can be present at any model simulation time. Large-scale effects are derived from observations and imposed into the model as the main forcing. The advantage of this approach is that the modeled convection will be forced to have the same intensity, thermodynamic budget and organization as the obserations.This approach will also allow CRMs to perform multi-day or multi-week time integrations. The second approach usually requires initial temperature and water vapor profiles that have a medium to large CAPE, and open lateral boundary conditions are used. The modeled clouds could be termed "self-forced convection". Model improvements, such as in the microphysics, are achieved using the second approach. In cloud ensemble modeling, accurate large-scale advective tendencies for temperature and water vapor are the main forcing for the CRMs. We found that the large-scale advective terms for temperature and water vapor are not always consistent, For example, large-scale forcing could indicate strong drying which would produce cooling in the model through evaporation but not contain large-scale advective heating to compensate. This discrepancy in forcing would cause differences between the observed and modeled latent heating profiles. Good measurements of other quantities (i.e., surface fluxes and radiation) are also required to perform variational objective analysis that computes and minimizes a "cost function" that constrains the difference between the large-scale advective forcing in temperature and water vapor. With self-forced convection, accurate vertical distributions of temperature, moisture (water vapor), and horizontal winds are required. The timing

  5. Cloud observations with Nimbus-7 satellite data

    NASA Technical Reports Server (NTRS)

    Stowe, L. L.; Hwang, P. H.; Bhartia, P. K.; Eck, T. F.

    1983-01-01

    A Nimbus-7 Cloud Data Processing Team was established in 1982 in order to implement cloud-related studies for as long as the spacecraft's Temperature Humidity IR radiometer and Total Ozone Mapping Spectrometer continue to operate. It will soon be possible to correlate the Nimbus-7 cloud cover information with International Satellite Cloud Climatology results. The production of validated Nimbus-7 cloud products was scheduled to begin in November, 1983; each year of Nimbus-7 cloud data should take about four months to produce.

  6. A climatologically significant aerosol longwave indirect effect in the Arctic

    NASA Astrophysics Data System (ADS)

    Lubin, Dan; Vogelmann, Andrew M.

    2006-01-01

    The warming of Arctic climate and decreases in sea ice thickness and extent observed over recent decades are believed to result from increased direct greenhouse gas forcing, changes in atmospheric dynamics having anthropogenic origin, and important positive reinforcements including ice-albedo and cloud-radiation feedbacks. The importance of cloud-radiation interactions is being investigated through advanced instrumentation deployed in the high Arctic since 1997 (refs 7, 8). These studies have established that clouds, via the dominance of longwave radiation, exert a net warming on the Arctic climate system throughout most of the year, except briefly during the summer. The Arctic region also experiences significant periodic influxes of anthropogenic aerosols, which originate from the industrial regions in lower latitudes. Here we use multisensor radiometric data to show that enhanced aerosol concentrations alter the microphysical properties of Arctic clouds, in a process known as the `first indirect' effect. Under frequently occurring cloud types we find that this leads to an increase of an average 3.4watts per square metre in the surface longwave fluxes. This is comparable to a warming effect from established greenhouse gases and implies that the observed longwave enhancement is climatologically significant.

  7. Toward Creating A Global Retrospective Climatology of Aerosol Properties

    NASA Technical Reports Server (NTRS)

    Curran, Robert J.; Mishchenko, Michael I.; Hansen, James E. (Technical Monitor)

    2000-01-01

    Tropospheric aerosols are thought to cause a significant direct and indirect climate forcing, but the magnitude of this forcing remains highly uncertain because of poor knowledge of global aerosol characteristics and their temporal changes. The standard long-term global product, the one-channel Advanced Very-High-Resolution Radiometer (AVHRR) aerosol optical thickness over the ocean, relies on a single predefined aerosol model and can be inaccurate in many cases. Furthermore, it provides no information on aerosol column number density, thus making it impossible to estimate the indirect aerosol effect on climate. Total Ozone Mapping Spectrometer (TOMS) data can be used to detect absorbing aerosols over land, but are insensitive to aerosols located below one kilometer. It is thus clear that innovative approaches must be employed in order to extract a more quantitative and accurate aerosol climatology from available satellite and other measurements, thus enabling more reliable estimates of the direct and indirect aerosol forcings. The Global Aerosol Climatology Project (GACP) was established in 1998 as part of the Global Energy and Water Cycle Experiment (GEWEX). Its main objective is to analyze satellite radiance measurements and field observations to infer the global distribution of aerosols, their properties, and their seasonal and interannual variations. The overall goal is to develop advanced global aerosol climatologies for the period of satellite data and to make the aerosol climatologies broadly available through the GACP web site.

  8. TRMM-Based Lightning Climatology

    NASA Technical Reports Server (NTRS)

    Cecil, Daniel J.; Buechler, Dennis E.; Blakeslee, Richard J.

    2011-01-01

    Gridded climatologies of total lightning flash rates seen by the spaceborne Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) have been updated. OTD collected data from May 1995 to March 2000. LIS data (equatorward of about 38 deg) has been added for 1998-2010. Flash counts from each instrument are scaled by the best available estimates of detection efficiency. The long LIS record makes the merged climatology most robust in the tropics and subtropics, while the high latitude data is entirely from OTD. The mean global flash rate from the merged climatology is 46 flashes per second. The peak annual flash rate at 0.5 deg scale is 160 fl/square km/yr in eastern Congo. The peak monthly average flash rate at 2.5 scale is 18 fl/square km/mo, from early April to early May in the Brahmaputra Valley of far eastern India. Lightning decreases in this region during the monsoon season, but increases further north and west. A monthly average peak from early August to early September in northern Pakistan also exceeds any monthly averages from Africa, despite central Africa having the greatest yearly average. Most continental regions away from the equator have an annual cycle with lightning flash rates peaking in late spring or summer. The main exceptions are India and southeast Asia, with springtime peaks in April and May. For landmasses near the equator, flash rates peak near the equinoxes. For many oceanic regions, the peak flash rates occur in autumn. This is particularly noticeable for the Mediterranean and North Atlantic. Landmasses have a strong diurnal cycle of lightning, with flash rates generally peaking between 3-5 pm local solar time. The central United States flash rates peak later, in late evening or early night. Flash rates peak after midnight in northern Argentina. These regions are known for large, intense, long-lived mesoscale convective systems.

  9. Characterising cloud regimes associated with the Southern Ocean shortwave radiation bias

    NASA Astrophysics Data System (ADS)

    Mason, S.; Jakob, C.; Protat, A.

    2013-12-01

    The high-latitude Southern Ocean is the site of persistent cloud biases in GCMs. A deficit of shortwave cloud radiative effect especially between 50-65S causes an excess of absorbed shortwave radiation, which has been associated with other biases in the global circulation. Recent model evaluation studies have found that the shortwave radiation bias is potentially associated with low- and mid-level clouds in the cold-air part of extratropical cyclones and ahead of transient ridges. However a coherent description of the cloud properties and cloud processes most associated with the bias has not yet emerged. This study focuses on three cloud regimes that are most frequent in the area of the shortwave radiation bias during the austral summer. They are selected from the cloud regimes derived for the Southern Ocean from International Satellite Cloud Climatology Project (ISCCP) cloud observations. We characterise the selected cloud regimes in terms of their meteorological conditions using the ECMWF Interim reanalysis. We also study their vertical macrophysical structure and microphysical properties based on active satellite observations using the DARDAR (raDAR/liDAR) combined CloudSat and CALIPSO data product. We find that two cloud regimes identified as mid-topped in the ISCCP based data set are associated with distinct meteorological processes. An optically thin mid-level top cloud regime is related to cold mid-levels, cold-air advection and moderate subsidence, while an optically thicker cloud regime is associated with a broader range of conditions resembling weak to moderate frontal events, with warm and moist mid-levels, moderate ascent and warm-air advection. The vertical cloud structure derived from DARDAR profiles show that both these regimes contain mostly low clouds, but both also include frequent occurrences of mid-level cloud. We use a clustering method to quantify the differences in microphysical properties between the regimes. We find that the optically

  10. Precipitation Characteristics of ISCCP Cloud Regimes for Improving Model Hydrological Budgets

    NASA Technical Reports Server (NTRS)

    Lee, D.; Oreopoulos, L.

    2011-01-01

    The key in unraveling relationships between precipitation and atmospheric circulations is their common linkage to clouds. Clouds can be described in a variety of ways and several approaches can be adopted to examine their connections to precipitation. We claim that when cloud regimes (aka weather states) from the International Satellite Cloud Climatology Project (ISCCP) are used to conditionally sample/sort and average precipitation data, useful insight and GCM-appropriate diagnostics on the origins and distribution of precipitation can be obtained. The ISCCP cloud regimes are mesoscale (2.5 ) cloud mixtures determined by cluster analysis on joint histograms of cloud optical thickness and cloud top pressure inferred from geostationary and polar orbiter satellite passive retrievals. The ISCCP cloud regime data are combined with GPCP IDD merged surface precipitation data and/or higher temporal and spatial resolution TRMM Multi-Satellite Precipitation Analysis (TMPA) data. The analysis is performed separately for three geographical zones, tropics, and northern/southern midlatitudes (for GPCP; only the tropics can be examined with TMPA data). Our presentation aspires to provide answers to the following questions: (l) What is the mean and variability of surface precipitation produced by each cloud regime at the time of regime occurrence? (2) What is the relative contribution of each cloud regime to the total precipitation within its geographical zone? (3) What is the geographical distribution of precipitation corresponding to particular cloud regime? (4) To what extent are the cloud regimes distinct in terms of their precipitation characteristics and is the regime ordering in terms of convective strength consistent with the observed precipitation intensity?

  11. 30 CFR 779.18 - Climatological information.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PROGRAMS SURFACE MINING PERMIT APPLICATIONS-MINIMUM REQUIREMENTS FOR INFORMATION ON ENVIRONMENTAL RESOURCES... shall contain a statement of the climatological factors that are representative of the proposed permit...

  12. 30 CFR 783.18 - Climatological information.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PROGRAMS UNDERGROUND MINING PERMIT APPLICATIONS-MINIMUM REQUIREMENTS FOR INFORMATION ON ENVIRONMENTAL... application shall contain a statement of the climatological factors that are representative of the proposed...

  13. A satellite and model based flood inundation climatology of Australia

    NASA Astrophysics Data System (ADS)

    Schumann, G.; Andreadis, K.; Castillo, C. J.

    2013-12-01

    To date there is no coherent and consistent database on observed or simulated flood event inundation and magnitude at large scales (continental to global). The only compiled data set showing a consistent history of flood inundation area and extent at a near global scale is provided by the MODIS-based Dartmouth Flood Observatory. However, MODIS satellite imagery is only available from 2000 and is hampered by a number of issues associated with flood mapping using optical images (e.g. classification algorithms, cloud cover, vegetation). Here, we present for the first time a proof-of-concept study in which we employ a computationally efficient 2-D hydrodynamic model (LISFLOOD-FP) complemented with a sub-grid channel formulation to generate a complete flood inundation climatology of the past 40 years (1973-2012) for the entire Australian continent. The model was built completely from freely available SRTM-derived data, including channel widths, bank heights and floodplain topography, which was corrected for vegetation canopy height using a global ICESat canopy dataset. Channel hydraulics were resolved using actual channel data and bathymetry was estimated within the model using hydraulic geometry. On the floodplain, the model simulated the flow paths and inundation variables at a 1 km resolution. The developed model was run over a period of 40 years and a floodplain inundation climatology was generated and compared to satellite flood event observations. Our proof-of-concept study demonstrates that this type of model can reliably simulate past flood events with reasonable accuracies both in time and space. The Australian model was forced with both observed flow climatology and VIC-simulated flows in order to assess the feasibility of a model-based flood inundation climatology at the global scale.

  14. Regional Ocean Climatologies: A New Line of Ocean Climate Research Tools

    NASA Astrophysics Data System (ADS)

    Mishonov, A. V.; Arzayus, K. M.; Baranova, O.; Boyer, T.; Parsons, A. R.; Seidov, D.

    2016-02-01

    National Centers for Environmental Information (NCEI) has recently begun developing a new line of products that are collectively defined as Regional Ocean Climatologies, or, when attributed to a specific region, just Regional Climatology (RC). There are five RC products developed to date—the Gulf of Mexico, East Asian Seas, Arctic & Greenland-Iceland-Norwegian Seas, and the Northwest Atlantic (NWA) RC. The newest NWA RC, which has been recently published (http://www.nodc.noaa.gov/OC5/regional_climate/nwa-climate/) is discussed in more details. A key for the success in generating a regional climatology is availability of historical oceanographic data in the selected region and the spatial data coverage sufficient for building an unambiguous statistics. In all five NCEI RCs, the data coverage is either good or acceptable in large parts of the selected regions. Therefore the regional climatology buildups were deemed successful and may become a useful tool for applied oceanographic research and projects. The annual and seasonal objectively analyzed temperature and salinity and in some cases other essential oceanographic parameters were substantiated in all mentioned climatologies at up to 1/10-degree spatial resolution. However, essential inherent problems arise in monthly fields assembled on the high resolution 1/10-degree grid. We are discussing some of these problems and conceivable approaches to address them using re-iterative quality control and subsequent climatology rerun cycles on the fine resolution grid. The re-iterative quality control facilitates better regional climatologies on decadal and longer scales. The NWA RC is used here to demonstrate superiority of the finer-resolution decadal climatologies over coarser-scale ones and exemplifies how the re-iterative quality control helps improving both finer and coarser-resolution decadal climatological fields. The climate pattern trends in the NWA region are being presented and discussed using a retrospective

  15. The effect of cloud type on Earth's energy balance - Global analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, Dennis L.; Ockert-Bell, Maureen E.; Michelsen, Marc L.

    1992-01-01

    The role of fractional area coverage by cloud types in the energy balance of the earth is investigated through joint use of International Satellite Cloud Climatology Project (ISCCP) C1 cloud data and Earth Radiation Budget Experiment (ERBE) broadband energy flux data for the one-year period March 1985 through February 1986. Multiple linear regression is used to relate the radiation budget data to the cloud data. Comparing cloud forcing estimates obtained from the ISCCP-ERBE regression with those derived from the ERBE scene identification shows generally good agreement except over snow, in tropical convective regions, and in regions that are either nearly cloudless or always overcast. It is suggested that a substantial fraction of the disagreement in longwave cloud forcing in tropical convective regions is associated with the fact that the ERBE scene identification does not take into account variations in upper-tropospheric water vapor. On a global average basis, low clouds make the largest contribution to the net energy balance of the Earth, because they cover such a large area and because their albedo effect dominates their effect on emitted thermal radiation. High, optically thick clouds can also very effectively reduce the energy balance, however, because their very high albedos overcome their low emission temperatures.

  16. The effect of cloud type on Earth's energy balance - Global analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, Dennis L.; Ockert-Bell, Maureen E.; Michelsen, Marc L.

    1992-01-01

    The role of fractional area coverage by cloud types in the energy balance of the earth is investigated through joint use of International Satellite Cloud Climatology Project (ISCCP) C1 cloud data and Earth Radiation Budget Experiment (ERBE) broadband energy flux data for the one-year period March 1985 through February 1986. Multiple linear regression is used to relate the radiation budget data to the cloud data. Comparing cloud forcing estimates obtained from the ISCCP-ERBE regression with those derived from the ERBE scene identification shows generally good agreement except over snow, in tropical convective regions, and in regions that are either nearly cloudless or always overcast. It is suggested that a substantial fraction of the disagreement in longwave cloud forcing in tropical convective regions is associated with the fact that the ERBE scene identification does not take into account variations in upper-tropospheric water vapor. On a global average basis, low clouds make the largest contribution to the net energy balance of the Earth, because they cover such a large area and because their albedo effect dominates their effect on emitted thermal radiation. High, optically thick clouds can also very effectively reduce the energy balance, however, because their very high albedos overcome their low emission temperatures.

  17. Radar and radiation properties of ice clouds

    SciTech Connect

    Atlas, D.; Heymsfield, A.J.

    1995-11-01

    The authors derive relations of the equivalent radar reflectivity Z{sub e} and extinction coefficient a of ice clouds and confirm the theory by in situ aircraft observations during the First International Satellite Cloud Climatology Project Regional Experiment. Equivalent radar reflectivity Z{sub e} is a function of ice water content Wand a moment of the size distribution such as the median volume diameter D{sub 0}. Stratification of the data by D{sub 0} provides a set of W-Z{sub e} relations from which one may deduce the dependence of particle density on size. This relation is close to that of Brown and Francis and provides confidence in the methodology of estimating particle size and mass. The authors find that there is no universal W-Z{sub e} relation, due both to large scatter and systematic shifts in particle size from day to day and cloud to cloud. These variations manifest the normal changes in ice crystal growth. The result is that, with the exception of temperatures less than -40{degrees}C, temperature cannot be used to reliably parameterize the particle size as has been previously suggested. To do so is to risk large possible systematic errors in retrievals. Even if one could measure monthly averages of ice water content, this is inadequate to estimate the monthly radiative effect because of the nonlinearity between the two. The authors show that a sizable fraction of radiatively significant clouds would be missed at a radar threshold of -30 dBZ, the value proposed for a spaceborne cloud-profiling radar. 29 refs., 13 figs., 3 tabs.

  18. 3D aerosol climatology over East Asia derived from CALIOP observations

    NASA Astrophysics Data System (ADS)

    Zhou, Yongbo; Sun, Xuejin; Zhang, Chuanliang; Zhang, Riwei; Li, Yan; Li, Haoran

    2017-03-01

    The seasonal mean extinction coefficient profile (ECP), single scattering albedo (SSA), and scattering phase function (SPF) derived from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) version 3 Level 2 5-km aerosol profile product (2011-2014) were compiled into a three-dimensional (3D) aerosol climatology for East Asia. The SSA and SPF were calculated as the weighted averages of the scattering properties of the CALIOP aerosol subtypes. The weights were set to the occurrence frequencies of the subtypes. The single scattering properties of each subtype were extrapolated from the volume-based size distribution and complex refractive indexes based on Mie calculations. For the high-loading episodes (aerosol optical depth ≥ 0.6), the exponential ECP structures were most frequently observed over the farmland and desert areas, along with the uplifted ECP structures over the marine and coastal areas. Besides the desert areas, high-loading episodes also occurred over areas with frequent agricultural and industry activities. Unlike the conventional half-3D aerosol climatology (vertically constant SSA and SPF), this newly generated climatology specified SSA and SPF in the full-3D space (full-3D aerosol climatology). Errors on the shortwave radiative heating rate (SW RHR) due to the half-3D aerosol climatology approximation were quantified. The SW RHR errors were around ±1 K/day, implying that the half-3D aerosol climatology should be used with caution in climate modeling. This study is among the first to generate a full-3D aerosol climatology from the CALIOP data. This full-3D aerosol climatology is potentially useful for aerosol remote sensing and climate modeling.

  19. The three-dimensional structure of cumulus clouds over the ocean. 1: Structural analysis

    NASA Technical Reports Server (NTRS)

    Kuo, Kwo-Sen; Welch, Ronald M.; Weger, Ronald C.; Engelstad, Mark A.; Sengupta, S. K.

    1993-01-01

    Thermal channel (channel 6, 10.4-12.5 micrometers) images of five Landsat thematic mapper cumulus scenes over the ocean are examined. These images are thresholded using the standard International Satellite Cloud Climatology Project (ISCCP) thermal threshold algorithm. The individual clouds in the cloud fields are segmented to obtain their structural statistics which include size distribution, orientation angle, horizontal aspect ratio, and perimeter-to-area (PtA) relationship. The cloud size distributions exhibit a double power law with the smaller clouds having a smaller absolute exponent. The cloud orientation angles, horizontal aspect ratios, and PtA exponents are found in good agreement with earlier studies. A technique also is developed to recognize individual cells within a cloud so that statistics of cloud cellular structure can be obtained. Cell structural statistics are computed for each cloud. Unicellular clouds are generally smaller (less than or equal to 1 km) and have smaller PtA exponents, while multicellular clouds are larger (greater than or equal to 1 km) and have larger PtA exponents. Cell structural statistics are similar to those of the smaller clouds. When each cell is approximated as a quadric surface using a linear least squares fit, most cells have the shape of a hyperboloid of one sheet, but about 15% of the cells are best modeled by a hyperboloid of two sheets. Less than 1% of the clouds are ellipsoidal. The number of cells in a cloud increases slightly faster than linearly with increasing cloud size. The mean nearest neighbor distance between cells in a cloud, however, appears to increase linearly with increasing cloud size and to reach a maximum when the cloud effective diameter is about 10 km; then it decreases with increasing cloud size. Sensitivity studies of threshold and lapse rate show that neither has a significant impact upon the results. A goodness-of-fit ratio is used to provide a quantitative measure of the individual cloud

  20. The three-dimensional structure of cumulus clouds over the ocean. 1: Structural analysis

    NASA Technical Reports Server (NTRS)

    Kuo, Kwo-Sen; Welch, Ronald M.; Weger, Ronald C.; Engelstad, Mark A.; Sengupta, S. K.

    1993-01-01

    Thermal channel (channel 6, 10.4-12.5 micrometers) images of five Landsat thematic mapper cumulus scenes over the ocean are examined. These images are thresholded using the standard International Satellite Cloud Climatology Project (ISCCP) thermal threshold algorithm. The individual clouds in the cloud fields are segmented to obtain their structural statistics which include size distribution, orientation angle, horizontal aspect ratio, and perimeter-to-area (PtA) relationship. The cloud size distributions exhibit a double power law with the smaller clouds having a smaller absolute exponent. The cloud orientation angles, horizontal aspect ratios, and PtA exponents are found in good agreement with earlier studies. A technique also is developed to recognize individual cells within a cloud so that statistics of cloud cellular structure can be obtained. Cell structural statistics are computed for each cloud. Unicellular clouds are generally smaller (less than or equal to 1 km) and have smaller PtA exponents, while multicellular clouds are larger (greater than or equal to 1 km) and have larger PtA exponents. Cell structural statistics are similar to those of the smaller clouds. When each cell is approximated as a quadric surface using a linear least squares fit, most cells have the shape of a hyperboloid of one sheet, but about 15% of the cells are best modeled by a hyperboloid of two sheets. Less than 1% of the clouds are ellipsoidal. The number of cells in a cloud increases slightly faster than linearly with increasing cloud size. The mean nearest neighbor distance between cells in a cloud, however, appears to increase linearly with increasing cloud size and to reach a maximum when the cloud effective diameter is about 10 km; then it decreases with increasing cloud size. Sensitivity studies of threshold and lapse rate show that neither has a significant impact upon the results. A goodness-of-fit ratio is used to provide a quantitative measure of the individual cloud

  1. The diabatic role of cloud and precipitation processes within mid-latitude storms: Results from the DIAMET project

    NASA Astrophysics Data System (ADS)

    Dearden, Chris; Vaughan, Geraint; Choularton, Tom

    2015-04-01

    We present an overview of research highlights from the DIAMET project (DIAbatic influences on Mesoscale structures in ExTratropical cyclones). DIAMET is a NERC-funded project that took place over four intensive observation periods between 2011 and 2012, providing detailed ground-based and in-situ measurements of a variety of severe weather systems affecting the UK. Here, we focus on the role of latent heating and cooling associated with cloud microphysical processes in terms of the dynamic evolution of mesoscale weather phenomena (e.g. fronts, rainbands and wind storms) embedded within synoptic scale storms. Ice processes are particularly complex and are treated relatively simplistically in weather forecast models, hence a review of the role of ice processes on mesoscale structures is urgently needed to assess whether existing parameterizations are fit for purpose in terms of representing diabatic effects. We begin with a review of the key findings from the aircraft cloud microphysics measurements made during DIAMET, and go on to discuss how these measurements have helped to inform the development of new and improved bulk microphysics schemes for use in mesoscale weather models. We also show how such models can be used to provide insight into the diabatic influence of microphysical processes in both summer and winter case studies.

  2. A study of temporal variability of clouds in exo-atmospheres using Earth observations as a proxy

    NASA Astrophysics Data System (ADS)

    Kopparla, Pushkar; Zhai, Albert; Zhai, Alice; Su, Hui; Jiang, Jonathan H.; Yung, Yuk Ling

    2015-11-01

    Clouds are strongly linked to the dynamics of the atmosphere, and have been observed to vary over multiple spatial scales and timescales on Earth and the planets: hourly, diurnal, seasonal, interannual and decadal. The study of such variations in exoplanetary atmospheres could only be made through lightly constrained general circulation models (GCMs). In most cases, the exoplanet itself is unresolved from its star and individual cloud patches and their variations cannot be observed. However, temporal and spatial variation of cloud fields can have significant implications for the interpreting the observed phase-curve of the lights from the star-exoplanet system, yet it remains almost wholly unconstrained. To address this issue, we model Earth as an exoplanet, to understand changes in observables due to temporal and spatial variations of clouds by leveraging the rich datasets available for Earth. In particular, the International Satellite Cloud Climatology Project (ISCCP) has compiled cloud observations on Earth in the past three decades, producing a high-resolution dataset. We perform radiative transfer calculations using cloud profiles sampled from this dataset to produce disc integrated brightness and polarization phase curves which map seasonal and interannual cloud variations. This exercise gives us the first (pseudo)-observation based constraints for temporal variability of clouds in exo-atmospheres.

  3. Web-based workflows to produce ocean climatologies using DIVA (Data-Interpolating Variational Analysis) and Jupyter notebooks

    NASA Astrophysics Data System (ADS)

    Barth, Alexander; Troupin, Charles; Watelet, Sylvain; Alvera-Azcarate, Aida; Beckers, Jean-Marie

    2017-04-01

    The analysis tool DIVA (Data-Interpolating Variational Analysis) is designed to generate gridded fields or climatologies from in situ observations. The tool DIVA minimizes a cost function to ensure that the analysed field is relatively close to the observations and conforms at the same time to a set of dynamical constraints. In particular, DIVA naturally decouples water bodies which are not directly connected and it uses a (potentially spatial varying) correlation length to describe over which length-scale the analysed variable is correlated. In addition, DIVA can also take ocean currents into account to introduce a preferential direction for the correlation. The SeaDataCloud project aims to facilitate the access and use of ocean in situ data from 45 national oceanographic data centres and marine data centres from 35 countries riparian to all European seas. A central aspect is to provide web-based virtual research environment, where scientists can easily access and explore the data sets through the SeaDataCloud infrastructure. For users familiar with programming languages like Julia and Python, Jupyter (acronym for Julia, Python and R) notebooks provide an exciting way to analyse and to interact with ocean data. Jupyter notebooks are made up of cells that can be run individually and can contain text, formulas or code fragment. A complete notebook explains how to go from input data and parameters to a result, in this case a gridded field obtained executing DIVA. This presentation discusses this new web-based workflow for generating climatologies using DIVA. It explores its new possibilities in particular, in terms of improved ease of use and reproducibility of the results. The integration in the infrastructure of EUDAT is also addressed.

  4. Climatology and Impact of Convection on the Tropical Tropopause Layer

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin; Pittman, Jasna

    2007-01-01

    Water vapor plays an important role in controlling the radiative balance and the chemical composition of the Tropical Tropopause Layer (TTL). Mechanisms ranging from slow transport and dehydration under thermodynamic equilibrium conditions to fast transport in convection have been proposed as regulators of the amount of water vapor in this layer. However,.details of these mechanisms and their relative importance remain poorly understood, The recently completed Tropical Composition, Cloud, and Climate Coupling (TC4) campaign had the opportunity to sample the.TTL over the Eastern Tropical Pacific using ground-based, airborne, and spaceborne instruments. The main goal of this study is to provide the climatological context for this campaign of deep and overshooting convective activity using various satellite observations collected during the summertime. We use the Microwave Humidity Sensor (MRS) aboard the NOAA-18 satellite to investigate the horizontal extent.and the frequency of convection reaching and penetrating into the TTL. We use the Moderate Resolution I1l1aging Spectroradiometer (MODIS) aboard the Aqua satellite to investigate the frequency distribution of daytime cirrus clouds. We use the Tropical Rainfall Measuring Mission(TRMM) and CloudSat to investigate the vertical structure and distribution of hydrometeors in the convective cells, In addition to cloud measurements; we investigate the impact that convection has on the concentration of radiatively important gases such as water vapor and ozone in the TTL by examining satellite measurement obtained from the Microwave Limb Sounder(MLS) aboard the Aura satellite.

  5. The Magnitude and Variability of Global and Regional Precipitation Based on the 22-Year GPCP (Global Precipitation Climatology Project) and Three-Year TRMM (Tropical Rainfall Measuring Mission) Data Sets

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.; Curtis, Scott; Huffman, George; Bolvin, David; Nelkin, Eric

    2001-01-01

    This paper gives an overview of the analysis of global precipitation over the last few decades and the impact of the new TRMM precipitation observations. The 20+ year, monthly, globally complete precipitation analysis of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP) is used to study global and regional variations and trends and is compared to the much shorter TRMM (Tropical Rainfall Measuring Mission) tropical data set. The GPCP data set shows no significant trend in precipitation over the twenty years, unlike the positive trend in global surface temperatures over the past century. The global trend analysis must be interpreted carefully, however, because the inhomogeneity of the data set makes detecting a small signal very difficult, especially over this relatively short period. Identifying regional trends in precipitation may be more practical. From 1979 to 1999 the northern mid-latitudes appear to be drying, the southern mid-latitudes have gotten wetter, and there is a mixed signal in the tropics. The relation between this field of trends and the relation to the frequency of El Nino events during this time period is explored. Monthly anomalies of precipitation are related to ENSO variations with clear signals extending into middle and high latitudes of both hemispheres. The El Nino and La Nina mean anomalies are near mirror images of each other and when combined produce an ENSO signal with significant spatial continuity over large distances. These El Nino minus La Nina composites of normalized precipitation show the usual positive, or wet, anomaly over the central and eastern Pacific Ocean with the negative, or dry, anomaly over the maritime continent along with an additional negative anomaly over Brazil and the Atlantic Ocean extending into Africa and a positive anomaly over the Horn of Africa and the western Indian Ocean. A number of the features are shown to extend into high latitudes. Positive anomalies

  6. Variations and Trends in Global and Regional Precipitation Based on the 22-Year GPCP (Global Precipitation Climatology Project) and Three-Year TRMM (Tropical Rainfall Measuring Mission) Data Sets

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.; Curtis, Scott; Huffman, George; Bolvin, David; Nelkin, Eric; Einaudi, Franco (Technical Monitor)

    2001-01-01

    This paper gives an overview of the analysis of global precipitation over the last few decades and the impact of the new TRMM precipitation observations. The 20+ year, monthly, globally complete precipitation analysis of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP) is used to study global and regional variations and trends and is compared to the much shorter TRMM(Tropical Rainfall Measuring Mission) tropical data set. The GPCP data set shows no significant trend in global precipitation over the twenty years, unlike the positive trend in global surface temperatures over the past century. The global trend analysis must be interpreted carefully, however, because the inhomogeneity of the data set makes detecting a small signal very difficult, especially over this relatively short period. The relation of global (and tropical) total precipitation and ENSO events is quantified with no significant signal when land and ocean are combined. Identifying regional trends in precipitation may be more practical. From 1979 to 2000 the tropics have pattern of regional rainfall trends that has an ENSO-like pattern with features of both the El Nino and La Nina. This feature is related to a possible trend in the frequency of ENSO events (either El Nino or La Nina) over the past 20 years. Monthly anomalies of precipitation are related to ENSO variations with clear signals extending into middle and high latitudes of both hemispheres. The El Nino and La Nina mean anomalies are near mirror images of each other and when combined produce an ENSO signal with significant spatial continuity over large distances. A number of the features are shown to extend into high latitudes. Positive anomalies extend in the Southern Hemisphere (S.H.) from the Pacific southeastward across Chile and Argentina into the south Atlantic Ocean. In the Northern Hemisphere (N.H.) the counterpart feature extends across the southern U.S. and Atlantic Ocean into Europe

  7. The Magnitude and Variability of Global and Regional Precipitation Based on the 22-Year GPCP (Global Precipitation Climatology Project) and Three-Year TRMM (Tropical Rainfall Measuring Mission) Data Sets

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.; Curtis, Scott; Huffman, George; Bolvin, David; Nelkin, Eric

    2001-01-01

    This paper gives an overview of the analysis of global precipitation over the last few decades and the impact of the new TRMM precipitation observations. The 20+ year, monthly, globally complete precipitation analysis of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP) is used to study global and regional variations and trends and is compared to the much shorter TRMM (Tropical Rainfall Measuring Mission) tropical data set. The GPCP data set shows no significant trend in precipitation over the twenty years, unlike the positive trend in global surface temperatures over the past century. The global trend analysis must be interpreted carefully, however, because the inhomogeneity of the data set makes detecting a small signal very difficult, especially over this relatively short period. Identifying regional trends in precipitation may be more practical. From 1979 to 1999 the northern mid-latitudes appear to be drying, the southern mid-latitudes have gotten wetter, and there is a mixed signal in the tropics. The relation between this field of trends and the relation to the frequency of El Nino events during this time period is explored. Monthly anomalies of precipitation are related to ENSO variations with clear signals extending into middle and high latitudes of both hemispheres. The El Nino and La Nina mean anomalies are near mirror images of each other and when combined produce an ENSO signal with significant spatial continuity over large distances. These El Nino minus La Nina composites of normalized precipitation show the usual positive, or wet, anomaly over the central and eastern Pacific Ocean with the negative, or dry, anomaly over the maritime continent along with an additional negative anomaly over Brazil and the Atlantic Ocean extending into Africa and a positive anomaly over the Horn of Africa and the western Indian Ocean. A number of the features are shown to extend into high latitudes. Positive anomalies

  8. Arctic Stratus Cloud Properties and Radiative Forcing Derived from Ground-Based Data Collected at Barrow, Alaska.

    NASA Astrophysics Data System (ADS)

    Dong, Xiquan; Mace, Gerald G.

    2003-02-01

    Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) Arctic Cloud Experiment (ACE) and the Surface Heat Budget of the Arctic Ocean (SHEBA) (77°N, 165°W) field experiments in 1998. The cloud microphysics derived from this study are similar, in general, to those collected in past field programs, although these comparisons are based on data collected at different locations and years. At the ARM NSA site, the summer cooling period is much longer (2-3 months vs 1-2 weeks), and the summer cooling magnitude is much larger (100 W m2 vs 5 W m2) than at the SHEBA ship under the conditions of all skies at the SHEBA and overcast low-level stratus clouds at the NSA site.

  9. Low cloud investigations for project FIRE: Island studies of cloud properties, surface radiation, and boundary layer dynamics. A simulation of the reflectivity over a stratocumulus cloud deck by the Monte Carlo method. M.S. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.; Lin, Ruei-Fong

    1993-01-01

    The radiation field over a broken stratocumulus cloud deck is simulated by the Monte Carlo method. We conducted four experiments to investigate the main factor for the observed shortwave reflectively over the FIRE flight 2 leg 5, in which reflectivity decreases almost linearly from the cloud center to cloud edge while the cloud top height and the brightness temperature remain almost constant through out the clouds. From our results, the geometry effect, however, did not contribute significantly to what has been observed. We found that the variation of the volume extinction coefficient as a function of its relative position in the cloud affects the reflectivity efficiently. Additional check of the brightness temperature of each experiment also confirms this conclusion. The cloud microphysical data showed some interesting features. We found that the cloud droplet spectrum is nearly log-normal distributed when the clouds were solid. However, whether the shift of cloud droplet spectrum toward the larger end is not certain. The decrease of number density from cloud center to cloud edges seems to have more significant effects on the optical properties.

  10. Automatic Cloud Bursting under FermiCloud

    SciTech Connect

    Wu, Hao; Shangping, Ren; Garzoglio, Gabriele; Timm, Steven; Bernabeu, Gerard; Kim, Hyun Woo; Chadwick, Keith; Jang, Haengjin; Noh, Seo-Young

    2013-01-01

    Cloud computing is changing the infrastructure upon which scientific computing depends from supercomputers and distributed computing clusters to a more elastic cloud-based structure. The service-oriented focus and elasticity of clouds can not only facilitate technology needs of emerging business but also shorten response time and reduce operational costs of traditional scientific applications. Fermi National Accelerator Laboratory (Fermilab) is currently in the process of building its own private cloud, FermiCloud, which allows the existing grid infrastructure to use dynamically provisioned resources on FermiCloud to accommodate increased but dynamic computation demand from scientists in the domains of High Energy Physics (HEP) and other research areas. Cloud infrastructure also allows to increase a private cloud’s resource capacity through “bursting” by borrowing or renting resources from other community or commercial clouds when needed. This paper introduces a joint project on building a cloud federation to support HEP applications between Fermi National Accelerator Laboratory and Korea Institution of Science and Technology Information, with technical contributions from the Illinois Institute of Technology. In particular, this paper presents two recent accomplishments of the joint project: (a) cloud bursting automation and (b) load balancer. Automatic cloud bursting allows computer resources to be dynamically reconfigured to meet users’ demands. The load balance algorithm which the cloud bursting depends on decides when and where new resources need to be allocated. Our preliminary prototyping and experiments have shown promising success, yet, they also have opened new challenges to be studied

  11. Cloud Condensation Nuclei in Fire-3

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The centerpiece of this research was the cloud condensation nuclei (CCN) measurements of the Desert Research Institute (DRI) CCN spectrometers on board the NCAR C-130 aircraft during the Arctic Cloud Experiment (ACE) in May, 1998. These instruments operated successfully throughout all eight 10-hour research flights based in Fairbanks and the two ferry flights between Colorado and Fairbanks. Within a few months of completion of ACE the CCN data was edited and put into the archives. A paper was completed and published on the CCN climatology during the previous two FIRE field projects-FIRE 1 based in San Diego in June and July, 1987 and ASTEX based in the Azores Islands in June, 1992. This showed distinct contrasts in concentrations and spectra between continental and maritime CCN concentrations, which depended on air mass trajectories. Pollution episodes from Europe had distinct influences on particle concentrations at low altitudes especially within the boundary layer. At higher altitudes concentrations were similar in the two air mass regimes. Cloudier atmospheres showed lower concentrations especially below the clouds, which were a result mostly of coalescence scavenging.

  12. Seasonal and Interannual Variations of Top-of-Atmosphere Irradiance and Cloud Cover over Polar Regions Derived from the CERES Data Set

    NASA Technical Reports Server (NTRS)

    Kato, Seiji; Loeb, Norman G.; Minnis, Patrick; Francis, Jennifer A.; Charlock, Thomas P.; Rutan, David A.; Clothiaux, Eugene E.; Sun-Mack, Szedung

    2006-01-01

    The semi-direct effects of dust aerosols are analyzed over eastern Asia using 2 years (June 2002 to June 2004) of data from the Clouds and the Earth s Radiant Energy System (CERES) scanning radiometer and MODerate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, and 18 years (1984 to 2001) of International Satellite Cloud Climatology Project (ISCCP) data. The results show that the water path of dust-contaminated clouds is considerably smaller than that of dust-free clouds. The mean ice water path (IWP) and liquid water path (LWP) of dusty clouds are less than their dust-free counterparts by 23.7% and 49.8%, respectively. The long-term statistical relationship derived from ISCCP also confirms that there is significant negative correlation between dust storm index and ISCCP cloud water path. These results suggest that dust aerosols warm clouds, increase the evaporation of cloud droplets and further reduce cloud water path, the so-called semi-direct effect. The semi-direct effect may play a role in cloud development over arid and semi-arid areas of East Asia and contribute to the reduction of precipitation.

  13. The SunCloud project: worldwide compilation of long-term series of sunshine duration and cloudiness observations

    NASA Astrophysics Data System (ADS)

    Sanchez-Lorenzo, Arturo; Pallé, Enric; Wild, Martin; Calbó, Josep; Brunetti, Michelle; Stanhill, Gerald; Brázdil, Rudolf; Barriendos, Mariano; Pereira, Paulo; Azorin-Molina, César

    2010-05-01

    One problem encountered when establishing the causes of global dimming and brightening is the limited number of long-term solar radiation series with accurate and calibrated measurements. For this reason, the analysis is often supported and extended with the use of other climatic variables such as diurnal temperature range, cloud cover, evaporation, visibility, or sunshine duration records. Moreover, it is of vital importance to study the reliability of the 'early brightening' identified by different studies during the first half of the 20th century, which cannot be detected by using the current downward solar radiation dataset. Therefore proxy variables are required again. Specifically, sunshine duration is defined as the amount of time usually expressed in hours that direct solar radiation exceeds a certain threshold (usually taken at 120 W m-2). Consequently, this variable can be considered as an excellent proxy measure of global and direct solar radiation at interannual and decadal time scales, with the advantage that measurements of this variable were initiated in the late 19th century in different main meteorological stations. Nevertheless, detailed and up-to-date analysis of sunshine duration behavior on global or hemispheric scales are still missing. Thus, in the framework of different research projects we will engage a worldwide compilation of the longest daily or monthly sunshine duration series from the late 19th century until present, using data freely available on the Internet or by means of direct contacts with meteorological institutions/individual researchers with access to long-term sunshine databases. We also plan to digitize long-term sunshine duration series when these become available only in analog format. Several quality control checks and homogenization methods will be applied to the generated sunshine dataset. The relationship between the more precise downward solar radiation series from the Global Energy Balance Archive (GEBA) and the

  14. Automated cloud classification with a fuzzy logic expert system

    NASA Technical Reports Server (NTRS)

    Tovinkere, Vasanth; Baum, Bryan A.

    1993-01-01

    An unresolved problem in current cloud retrieval algorithms concerns the analysis of scenes containing overlapping cloud layers. Cloud parameterizations are very important both in global climate models and in studies of the Earth's radiation budget. Most cloud retrieval schemes, such as the bispectral method used by the International Satellite Cloud Climatology Project (ISCCP), have no way of determining whether overlapping cloud layers exist in any group of satellite pixels. One promising method uses fuzzy logic to determine whether mixed cloud and/or surface types exist within a group of pixels, such as cirrus, land, and water, or cirrus and stratus. When two or more class types are present, fuzzy logic uses membership values to assign the group of pixels partially to the different class types. The strength of fuzzy logic lies in its ability to work with patterns that may include more than one class, facilitating greater information extraction from satellite radiometric data. The development of the fuzzy logic rule-based expert system involves training the fuzzy classifier with spectral and textural features calculated from accurately labeled 32x32 regions of Advanced Very High Resolution Radiometer (AVHRR) 1.1-km data. The spectral data consists of AVHRR channels 1 (0.55-0.68 mu m), 2 (0.725-1.1 mu m), 3 (3.55-3.93 mu m), 4 (10.5-11.5 mu m), and 5 (11.5-12.5 mu m), which include visible, near-infrared, and infrared window regions. The textural features are based on the gray level difference vector (GLDV) method. A sophisticated new interactive visual image Classification System (IVICS) is used to label samples chosen from scenes collected during the FIRE IFO II. The training samples are chosen from predefined classes, chosen to be ocean, land, unbroken stratiform, broken stratiform, and cirrus. The November 28, 1991 NOAA overpasses contain complex multilevel cloud situations ideal for training and validating the fuzzy logic expert system.

  15. FINAL REPORT FOR THE DOE/ARM PROJECT TITLED Representation of the Microphysical and Radiative Properties of Ice Clouds in SCMs and GCMs

    SciTech Connect

    Mitchell, David L.

    2005-08-08

    The broad goal of this research is to improve climate prediction through better representation of cirrus cloud microphysical and radiative properties in global climate models (GCMs). Clouds still represent the greatest source of uncertainty in climate prediction, and the representation of ice clouds is considerably more challenging than liquid water clouds. While about 40% of cloud condensate may be in the form of ice by some estimates, there have been no credible means of representing the ice particle size distribution and mass removal rates from ice clouds in GCMs. Both factors introduce large uncertainties regarding the global net flux, the latter factor alone producing a change of 10 W/m2 in the global net flux due to plausible changes in effective ice particle fallspeed. In addition, the radiative properties of ice crystals themselves are in question. This research provides GCMs with a credible means of representing the full (bimodal) ice particle size distribution (PSD) in ice clouds, including estimates of the small crystal (D < 65 microns) mode of the PSD. It also provides realistic estimates of mass sedimentation rates from ice clouds, which have a strong impact on their ice contents and radiative properties. This can be done through proper analysis of ice cloud microphysical data from ARM and other field campaigns. In addition, this research tests the ice cloud radiation treatment developed under two previous ARM projects by comparing it against laboratory measurements of ice cloud extinction efficiency and by comparing it with explicit theoretical calculations of ice crystal optical properties. The outcome of this project includes two PSD schemes for ice clouds; one appropriate for mid-latitude cirrus clouds and another for tropical anvil cirrus. Cloud temperature and ice water content (IWC) are the inputs for these PSD schemes, which are based on numerous PSD observations. The temperature dependence of the small crystal mode of the PSD for tropical

  16. Spatial and Temporal Variability of Satellite-Derived Cloud and Surface Characteristics During FIRE-ACE

    NASA Technical Reports Server (NTRS)

    Maslanik, J. A.; Key, J.; Fowler, C. W.; Nguyen, T.; Wang, X.a

    2000-01-01

    Advanced very high resolution radiometer (AVHRR) products calculated for the western Arctic for April-July 1998 are used to investigate spatial, temporal, and regional patterns and variability in energy budget parameters associated with ocean- ice-atmosphere interactions over the Arctic Ocean during the Surface Heat Budget of the Arctic Ocean (SHEBA) project and the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). The AVHRR-derived parameters include cloud fraction, clear-sky and all-sky skin temperature and broadband albedo, upwelling and downwelling shortwave and longwave radiation, cloud top pressure and temperature, and cloud optical depth. The remotely sensed products generally agree well with field observations at the SHEBA site, which in turn is shown to be representative of a surrounding region comparable in size to a climate-model grid cell. Time series of products for other locations in the western Arctic illustrate the magnitude of spatial variability during the study period and provide spatial and temporal detail useful for studying regional processes. The data illustrate the progression of reduction in cloud cover, albedo decrease, and the considerable heating of the open ocean associated with the anomalous decrease in sea ice cover in the eastern Beaufort Sea that began in late spring. Above-freezing temperatures are also recorded within the ice pack, suggesting warming of the open water areas within the ice cover.

  17. The role of global cloud climatologies in validating numerical models

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN

    1993-01-01

    The purpose of this work is to estimate sampling errors of area-time averaged rain rate due to temporal samplings by satellites. In particular, the sampling errors of the proposed low inclination orbit satellite of the Tropical Rainfall Measuring Mission (TRMM) (35 deg inclination and 350 km altitude), one of the sun synchronous polar orbiting satellites of NOAA series (98.89 deg inclination and 833 km altitude), and two simultaneous sun synchronous polar orbiting satellites--assumed to carry a perfect passive microwave sensor for direct rainfall measurements--will be estimated. This estimate is done by performing a study of the satellite orbits and the autocovariance function of the area-averaged rain rate time series. A model based on an exponential fit of the autocovariance function is used for actual calculations. Varying visiting intervals and total coverage of averaging area on each visit by the satellites are taken into account in the model. The data are generated by a General Circulation Model (GCM). The model has a diurnal cycle and parameterized convective processes. A special run of the GCM was made at NASA/GSFC in which the rainfall and precipitable water fields were retained globally for every hour of the run for the whole year.

  18. Estimation of cirrus cloud particle fallspeeds from vertically pointing Doppler radar

    NASA Technical Reports Server (NTRS)

    Orr, Brad W.; Kropfli, Robert A.

    1993-01-01

    The First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment 2 (FIRE 2) was conducted in Coffeyville, Kansas in late 1991 to study the microphysical and radiative properties of cirrus clouds. A variety of active and passive remote sensors were employed, including an 8-mm-wavelength cloud-sensing Doppler radar developed at the Wave Propagation Laboratory (WPL). The radar, having excellent sensitivity to cloud particles (-30 dBZ at 10 km), good spatial resolution (37 m), and velocity precision (.05 ms -1), is an excellent tool for observing cirrus clouds. Having this radar directed toward the zenith for long periods of time during FIRE 2 permitted the reflectivity-weighted particle fallspeed to be related to reflectivity which allowed a separation of ice particle fallspeeds from vertical air motions. Additionally, such relationships proved useful in other multi-sensor techniques for determining vertical profiles of ice particle characteristic size and ice water content in cirrus clouds. The analysis method and the results of applying it to cirrus cloud reflectivity and velocity data collected during FIRE 2 are discussed.

  19. The Araucaria Project. The Distance to the Small Magellanic Cloud from Late-type Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Graczyk, Dariusz; Pietrzyński, Grzegorz; Thompson, Ian B.; Gieren, Wolfgang; Pilecki, Bogumił; Konorski, Piotr; Udalski, Andrzej; Soszyński, Igor; Villanova, Sandro; Górski, Marek; Suchomska, Ksenia; Karczmarek, Paulina; Kudritzki, Rolf-Peter; Bresolin, Fabio; Gallenne, Alexandre

    2014-01-01

    We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long-period, late-type eclipsing binaries discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m - M) = 18.99 with a dispersion of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007, we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the Large Magellanic Cloud equal to 0.458 ± 0.068 mag. Finally, we advocate μSMC = 18.95 ± 0.07 as a new "canonical" value of the distance modulus to this galaxy.

  20. The Araucaria project. The distance to the small Magellanic Cloud from late-type eclipsing binaries

    SciTech Connect

    Graczyk, Dariusz; Pietrzyński, Grzegorz; Gieren, Wolfgang; Pilecki, Bogumił; Villanova, Sandro; Gallenne, Alexandre; Thompson, Ian B.; Konorski, Piotr; Udalski, Andrzej; Soszyński, Igor; Górski, Marek; Suchomska, Ksenia; Karczmarek, Paulina; Kudritzki, Rolf-Peter; Bresolin, Fabio

    2014-01-01

    We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long-period, late-type eclipsing binaries discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m – M) = 18.99 with a dispersion of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007, we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the Large Magellanic Cloud equal to 0.458 ± 0.068 mag. Finally, we advocate μ{sub SMC} = 18.95 ± 0.07 as a new 'canonical' value of the distance modulus to this galaxy.

  1. Introduction to Global Urban Climatology

    NASA Astrophysics Data System (ADS)

    Varquez, A. C. G.; Kanda, M.; Kawano, N.; Darmanto, N. S.; Dong, Y.

    2016-12-01

    Urban heat island (UHI) is a widely investigated phenomenon in the field of urban climate characterized by the warming of urban areas relative to its surrounding rural environs. Being able to understand the mechanism behind the UHI formation of a city and distinguish its impact from that of global climate change is indispensable when identifying adaptation and mitigation strategies. However, the lack of UHI studies many cities especially for developing countries makes it difficult to generalize the mechanism for UHI formation. Thus, there is an impending demand for studies that focus on the simultaneous analyses of UHI and its trends throughout the world. Hence, we propose a subfield of urban climatology, called "global urban climatology" (GUC), which mainly focuses on the uniform understanding of urban climates across all cities, globally. By using globally applicable methodologies to quantify and compare urban heat islands of cities with diverse backgrounds, including their geography, climate, socio-demography, and other factors, a universal understanding of the mechanisms underlying the formation of the phenomenon can be established. The implementation of GUC involves the use of globally acquired historical observation networks, gridded meteorological parameters from climate models, global geographic information system datasets; the construction of a distributed urban parameter database; and the development of techniques necessary to model the urban climate. Research under GUC can be categorized into three approaches. The collaborative approach (1st) relies on the collection of data from micro-scale experiments conducted worldwide with the aid or development of professional social networking platforms; the analytical approach (2nd) relies on the use of global weather station datasets and their corresponding objectively analysed global outputs; and the numerical approach (3rd) relies on the global estimation of high-resolution urban-representative parameters as

  2. Tower Mesonetwork Climatology and Interactive Display Tool

    NASA Technical Reports Server (NTRS)

    Case, Jonathan L.; Bauman, William H., III

    2004-01-01

    Forecasters at the 45th Weather Squadron and Spaceflight Meteorology Group use data from the tower network over the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) to evaluate Launch Commit Criteria, and issue and verify forecasts for ground operations. Systematic biases in these parameters could adversely affect an analysis, forecast, or verification. Also, substantial geographical variations in temperature and wind speed can occur under specific wind directions. To address these concerns, the Applied Meteorology Unit (AMU) developed a climatology of temperatures and winds from the tower network, and identified the geographical variation and significant tower biases. The mesoclimate is largely driven by the complex land-water interfaces across KSC/CCAFS. Towers with close proximity to water typically had much warmer nocturnal temperatures and higher wind speeds throughout the year. The strongest nocturnal wind speeds occurred from October to March whereas the strongest mean daytime wind speeds occurred from February to May. These results of this project can be viewed by forecasters through an interactive graphical user interface developed by the AMU. The web-based interface includes graphical and map displays of mean, standard deviation, bias, and data availability for any combination of towers, variables, months, hours, and wind directions.

  3. Global Climatology of Surface Precipitation: Role of TRMM and GPM

    NASA Astrophysics Data System (ADS)

    Adler, R. F.; Wang, J.; Gu, G.

    2011-12-01

    An accurate estimate of global and regional precipitation in terms of climatology, inter-annual variations and trends is critical to understand our planet's state in terms of water availability and the impact of climate change phenomena such as global warming. The Global Precipitation Climatology Project (GPCP) data set has been a highly used satellite and gauge merged product for studies in these areas. Data from the Tropical Rainfall Measuring Mission (TRMM), now spanning almost 14 years in length, is considered to be the most accurate satellite estimation of tropical precipitation, due to its passive microwave, radar and combined estimates of surface precipitation. The Global Precipitation Measurement (GPM) mission will follow in TRMM's footsteps, improving the quality of the precipitation estimations even more with improved instrumentation and expanding the latitude range to middle and high latitudes. The development of accurate climatologies and even monthly estimates from these missions will be valuable in themselves, but also presents an opportunity to incorporate their advanced information into merged, long-term observational data sets such as the GPCP analysis. An example of the use of TRMM (and eventually GPM) data in developing a new tropical climatology will be described as the TRMM Composite Climatology (TCC), based on a combination of thirteen years (1998-2010) of various precipitation products (Version 6) from TRMM. The TCC consists of a merger of three selected TRMM rainfall products over both land and ocean to give a "TRMM-best" climatological estimate. Inputs to the composite were selected based on knowledge of the performance of the retrievals, limitations of the algorithms, and the presence of artifacts. In addition to the mean precipitation estimates, the TCC includes the variation among the three estimates at each point to give an estimate of the error in the estimated mean value. Comparison of the TCC with validation data and with the GPCP

  4. A Climatology of Central American Gyres

    NASA Astrophysics Data System (ADS)

    Papin, P. P.; Griffin, K. S.; Bosart, L. F.; Torn, R. D.

    2012-12-01

    Monsoon gyres, commonly found over the western Pacific Ocean, are characterized by broad low-level cyclonic circulations that occur at a variety of spatial scales ranging from 1500-3000 km. Low-level cyclonic gyre circulations, while less frequent and occupying a smaller scale, have also been observed over Central America during the tropical cyclone (TC) season. A noteworthy gyre observed during the 2010 PREDICT field project served as a "collector" of TC Matthew and a source for TC Nicole. During October 2011, devastating flooding occurred in Guatemala and El Salvador when TD 12-E, embedded in a gyre circulation, made landfall on the Pacific coast of Central America. These gyre occurrences, their apparent links to TC activity, and their association with high-impact weather motivates this presentation. A preliminary analysis of Central American gyres suggests that their spatial scales vary between 1000-2000 km. These gyres also tend to be co-located with reservoirs of deep moisture that are characterized by high precipitable water values (>50 mm) and embedded deep convection on their southern and eastern sides. Catastrophic flooding can occur when gyre cyclonic circulations interact with the topography of Central America. A Central American gyre climatology including gyre frequency over the TC season and individual gyre duration will be presented. This climatology is then used to craft a gyre composite using previous gyre cases from 1980-2010. Particular attention will be given to the common synoptic and sub-synoptic scale features that precede and take place during gyre formation. This includes the role that intraseasonal and interannual circulations such as the Madden-Julian Oscillation (MJO) and El Nino-Southern Oscillation (ENSO) might play in gyre development. TC genesis events within gyre circulations will also be highlighted and examined further. Finally, the results of a September 2010 case study will be used to illustrate the impact that Central American

  5. Tropical cloud and precipitation regimes as seen from near-simultaneous TRMM, CloudSat, and CALIPSO observations and comparison with ISCCP

    NASA Astrophysics Data System (ADS)

    Luo, Zhengzhao Johnny; Anderson, Ricardo C.; Rossow, William B.; Takahashi, Hanii

    2017-06-01

    Although Tropical Rainfall Measuring Mission (TRMM) and CloudSat/CALIPSO fly in different orbits, they frequently cross each other so that for the period between 2006 and 2010, a total of 15,986 intersect lines occurred within 20 min of each other from 30°S to 30°N, providing a rare opportunity to study tropical cloud and precipitation regimes and their internal vertical structure from near-simultaneous measurements by these active sensors. A k-means cluster analysis of TRMM and CloudSat matchups identifies three tropical cloud and precipitation regimes: the first two regimes correspond to, respectively, organized deep convection with heavy rain and cirrus anvils with moderate rain; the third regime is a convectively suppressed regime that can be further divided into three subregimes, which correspond to, respectively, stratocumulus clouds with drizzle, cirrus overlying low clouds, and nonprecipitating cumulus. Inclusion of CALIPSO data adds to the dynamic range of cloud properties and identifies one more cluster; subcluster analysis further identifies a thin, midlevel cloud regime associated with tropical mountain ranges. The radar-lidar cloud regimes are compared with the International Satellite Cloud Climatology Project (ISCCP) weather states (WSs) for the extended tropics. Focus is placed on the four convectively active WSs, namely, WS1-WS4. ISCCP WS1 and WS2 are found to be counterparts of Regime 1 and Regime 2 in radar-lidar observations, respectively. ISCCP WS3 and WS4, which are mainly isolated convection and broken, detached cirrus, do not have a strong association with any individual radar and lidar regimes, a likely effect of the different sampling strategies between ISCCP and active sensors and patchy cloudiness of these WSs.

  6. Ionospheric Climatology Over Millstone Hill

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Holt, J. M.

    2002-05-01

    26 years of incoherent scatter observations over Millstone Hill since 1976 have been analyzed and modeled in order to study the climatological behavior in the local ionosphere-thermosphere system. A bin-fit technique is applied to process and represent the huge volume of data: measurements are binned according to local time, season, and altitude; sorted data in each bin are fitted into an empirical model where solar activity index F107 and geomagnetical activity index Ap are included as keyed inputs [Holt et al., 2002]. This paper focuses on seasonal, semiannual and annual variations and the long-term trend in electron density, electron temperature and ion temperature measurements over a 200-500 km height range of the F2 layer. A clear semiannual variation of the electron density is seen above the F2 peak during the day, as well as at the F2 peak and below during the later afternoon to evening period (16-20LT) . The semiannual variation of the electron temperature persists with minimum at equinox during the night, while the annual variation prevails by day with maximum in summer.

  7. Separation of cirrus cloud from clear surface from AVIRIS data using the 1.38 micron water vapor band

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Goetz, Alexander F. H.

    1992-01-01

    Cirrus clouds play an important role in climate systems because of their large area coverage, persistence, and radiative effects. Thin cirrus clouds are difficult to detect in visible images and infrared images in the 10-12 micron atmospheric window region, particularly over land, because these clouds are partially transparent. Ackerman recently developed a method for detecting cirrus clouds using three narrow channels centered near 8, 11, and 12 microns, respectively, based on the analysis of IR emission spectra measured with a high spectral resolution interferometer. Barton also described a method for estimating cirrus cloud height and amount from measurements with two narrow channel radiometers of the Selective Chopper Radiometer on Nimbus 5. Both channels are located within the strong 2.7 micron water vapor band absorption region. One of the channels includes additional carbon dioxide absorption. A differential absorption technique with sets of empirical coefficients was used in the estimation of cirrus cloud heights and amounts. A technique using narrow channels in the strong 1.38 micron water vapor band absorption region for detecting cirrus clouds from spectral imaging data acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) on 5 Dec. 1991 during the FIRE (The First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment) Phase 2 Field Experiment is described.

  8. Cloud Radiative Effect in dependence on Cloud Type

    NASA Astrophysics Data System (ADS)

    Aebi, Christine; Gröbner, Julian; Kämpfer, Niklaus; Vuilleumier, Laurent

    2015-04-01

    Radiative transfer of energy in the atmosphere and the influence of clouds on the radiation budget remain the greatest sources of uncertainty in the simulation of climate change. Small changes in cloudiness and radiation can have large impacts on the Earth's climate. In order to assess the opposing effects of clouds on the radiation budget and the corresponding changes, frequent and more precise radiation and cloud observations are necessary. The role of clouds on the surface radiation budget is studied in order to quantify the longwave, shortwave and the total cloud radiative forcing in dependence on the atmospheric composition and cloud type. The study is performed for three different sites in Switzerland at three different altitude levels: Payerne (490 m asl), Davos (1'560 m asl) and Jungfraujoch (3'580 m asl). On the basis of data of visible all-sky camera systems at the three aforementioned stations in Switzerland, up to six different cloud types are distinguished (Cirrus-Cirrostratus, Cirrocumulus-Altocumulus, Stratus-Altostratus, Cumulus, Stratocumulus and Cumulonimbus-Nimbostratus). These cloud types are classified with a modified algorithm of Heinle et al. (2010). This cloud type classifying algorithm is based on a set of statistical features describing the color (spectral features) and the texture of an image (textural features) (Wacker et al. (2015)). The calculation of the fractional cloud cover information is based on spectral information of the all-sky camera data. The radiation data are taken from measurements with pyranometers and pyrgeometers at the different stations. A climatology of a whole year of the shortwave, longwave and total cloud radiative effect and its sensitivity to integrated water vapor, cloud cover and cloud type will be calculated for the three above-mentioned stations in Switzerland. For the calculation of the shortwave and longwave cloud radiative effect the corresponding cloud-free reference models developed at PMOD/WRC will be

  9. [An automatic extraction algorithm for individual tree crown projection area and volume based on 3D point cloud data].

    PubMed

    Xu, Wei-Heng; Feng, Zhong-Ke; Su, Zhi-Fang; Xu, Hui; Jiao, You-Quan; Deng, Ou

    2014-02-01

    fixed angles to estimate crown projections, and (2) different regular volume formula to simulate crown volume according to the tree crown shapes. Based on the high-resolution 3D LIDAR point cloud data of individual tree, tree crown structure was reconstructed at a high rate of speed with high accuracy, and crown projection and volume of individual tree were extracted by this automatical untouched method, which can provide a reference for tree crown structure studies and be worth to popularize in the field of precision forestry.

  10. 77 FR 53839 - Shasta-Trinity National Forest; California; East McCloud Plantations Thinning Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-04

    ... such as drought, insect and disease infestations and severe wildfire. Treatments would include... damage, mistletoe infestations and severe wildfire. Recent drought conditions in the western United... project area is susceptible to uncharacteristically severe, stand- destroying wildfire due to...

  11. Climatological data summary 1993 with historical data

    SciTech Connect

    Hoitink, D.J.; Burk, K.W.

    1994-06-01

    This document presents the climatological data summary for calendar year 1993. It presents updated historical climatologies for temperature, wind, precipitation, and other miscellaneous meteorological parameters from the Hanford Meteorology Station (HMS) and Hanford Meteorological Monitoring Network. It also presents climatological normal and extreme values of temperature and precipitation for the HMS. Previous documents have included climatological data collected at the old Hanford Townsite, located approximately 10 miles east-northeast of the present HMS. The records for these two different sites have been frequently interchanged as if representing the same location. With the exception of Section 2.0, the remainder of this document uses data only from the HMS, with a period of record beginning December 7, 1944.

  12. A climatological link between slantwise instability and surface weather conditions

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  13. Cloud Front

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02171 Cloud Front

    These clouds formed in the south polar region. The faintness of the cloud system likely indicates that these are mainly ice clouds, with relatively little dust content.

    Image information: VIS instrument. Latitude -86.7N, Longitude 212.3E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. An Argo mixed layer climatology and database

    NASA Astrophysics Data System (ADS)

    Holte, James; Talley, Lynne D.; Gilson, John; Roemmich, Dean

    2017-06-01

    A global climatology and database of mixed layer properties are computed from nearly 1,250,000 Argo profiles. The climatology is calculated with both a hybrid algorithm for detecting the mixed layer depth (MLD) and a standard threshold method. The climatology provides accurate information about the depth, properties, extent, and seasonal patterns of global mixed layers. The individual profile results in the database can be used to construct time series of mixed layer properties in specific regions of interest. The climatology and database are available online at http://mixedlayer.ucsd.edu. The MLDs calculated by the hybrid algorithm are shallower and generally more accurate than those of the threshold method, particularly in regions of deep winter mixed layers; the new climatology differs the most from existing mixed layer climatologies in these regions. Examples are presented from the Labrador and Irminger Seas, the Southern Ocean, and the North Atlantic Ocean near the Gulf Stream. In these regions the threshold method tends to overestimate winter MLDs by approximately 10% compared to the algorithm.

  15. NIMBUS 3 and 4 Visible Image Climatology: 1969 and 1970

    NASA Astrophysics Data System (ADS)

    Campbell, G. G.; Gallaher, D. W.

    2014-12-01

    The Nimbus 3 and Nimbus 4 satellites collected visible imagery with the Image Dissection Camera System, IDCS. We recovered this data from 70mm black and white film by digitizing the images and then providing navigation and timing meta data. As in previous studies we will discuss the sea ice extent around Antarctica as well as in the Arctic with new information about 1970 and 1971. We now have a chance to look at a full seasonal cycle of sea ice changes long before the current records. Comparisons with Ice Core proxy estimates (Curran et al.) of sea ice extent will be presented. Also we will discuss a new use of the data: measuring the variation of tropical convection. Specifically could this Nimbus data extend the Highly Reflective Cloud Climatology (1971 to 1988).

  16. Biomes computed from simulated climatologies

    NASA Astrophysics Data System (ADS)

    Claussen, Martin; Esch, Monika

    1994-01-01

    The biome model of Prentice et al. (1992a) is used to predict global patterns of potential natural plant formations, or biomes, from climatologies simulated by ECHAM, a model used for climate simulations at the Max-Planck-Institut fur Meteorologie. This study is undertaken in order to show the advantage of this biome model in diagnosing the performance of a climate model and assessing effects of past and future climate changes predicted by a climate model. Good overall agreement is found between global patterns of biomes computed from observed and simulated data of present climate. But there are also major discrepancies indicated by a difference in biomes in Australia, in the Kalahari Desert, and in the Middle West of North America. These discrepancies can be traced back to failures in simulated rainfall as well as summer or winter temperatures. Global patterns of biomes computed from an ice age simulation reveal that North America, Europe, and Siberia should have been covered largely by tundra and taiga, whereas only small differences are seen for the tropical rain forests. A potential northeast shift of biomes is expected from a simulation with enhanced C02 concentration according to the IPCC Scenario A. Little change is seen in the tropical rain forest and the Sahara. Since the biome model used is not capable of predicting changes in vegetation patterns due to a rapid climate change, the latter simulation has to be taken as a prediction of changes in conditions favourable for the existence of certain biomes, not as a prediction of a future distribution of biomes.[/ab

  17. Biomes computed from simulated climatologies

    SciTech Connect

    Claussen, M.; Esch, M.

    1994-01-01

    The biome model of Prentice et al. is used to predict global patterns of potential natural plant formations, or biomes, from climatologies simulated by ECHAM, a model used for climate simulations at the Max-Planck-Institut fuer Meteorologie. This study undertaken in order to show the advantage of this biome model in diagnosing the performance of a climate model and assessing effects of past and future climate changes predicted by a climate model. Good overall agreement is found between global patterns of biomes computed from observed and simulated data of present climate. But there are also major discrepancies indicated by a difference in biomes in Australia, in the Kalahari Desert, and in the Middle West of North America. These discrepancies can be traced back to in simulated rainfall as well as summer or winter temperatures. Global patterns of biomes computed from an ice age simulation reveal that North America, Europe, and Siberia should have been covered largely by tundra and taiga, whereas only small differences are for the tropical rain forests. A potential northeast shift of biomes is expected from a simulation with enhanced CO{sub 2} concentration according to the IPCC Scenario A. Little change is seen in the tropical rain forest and the Sahara. Since the biome model used is not capable of predicting chances in vegetation patterns due to a rapid climate change, the latter simulation to be taken as a prediction of chances in conditions favourable for the existence of certain biomes, not as a reduction of a future distribution of biomes. 15 refs., 8 figs., 2 tabs.

  18. Using DOE-ARM and Space-Based Assets to Assess the Quality of Air Force Weather 3D Cloud Analysis and Forecast Products

    NASA Astrophysics Data System (ADS)

    Nobis, T. E.

    2015-12-01

    Air Force Weather (AFW) has documented requirements for global cloud analysis and forecasting to support DoD missions around the world. To meet these needs, AFW utilizes a number of cloud products. Cloud analyses are constructed using 17 different near real time satellite sources. Products include analysis of the individual satellite transmissions at native satellite resolution and an hourly global merge of all 17 sources on a 24km grid. AFW has also recently started creation of a time delayed global cloud reanalysis to produce a 'best possible' analysis for climatology and verification purposes. Forecasted cloud products include global short-range cloud forecasts created using advection techniques as well as statistically post processed cloud forecast products derived from various global and regional numerical weather forecast models. All of these cloud products cover different spatial and temporal resolutions and are produced on a number of different grid projections. The longer term vision of AFW is to consolidate these various approaches into uniform global numerical weather modeling (NWM) system using advanced cloudy-data assimilation processes to construct the analysis and a licensed version of UKMO's Unified Model to produce the various cloud forecast products. In preparation for this evolution in cloud modeling support, AFW has started to aggressively benchmark the performance of their current capabilities. Cloud information collected from so called 'active' sensors on the ground at the DOE-ARM sites and from space by such instruments as CloudSat, CALIPSO and CATS are being utilized to characterize the performance of AFW products derived largely by passive means. The goal is to understand the performance of the 3D cloud analysis and forecast products of today to help shape the requirements and standards for the future NWM driven system.This presentation will present selected results from these benchmarking efforts and highlight insights and observations

  19. The SunCloud project: An initiative for a development of a worldwide sunshine duration and cloudiness observations dataset

    NASA Astrophysics Data System (ADS)

    Sanchez-Lorenzo, A.

    2010-09-01

    One problem encountered when establishing the causes of global dimming and brightening is the limited number of long-term solar radiation series with accurate and calibrated measurements. For this reason, the analysis is often supported and extended with the use of other climatic variables such as sunshine duration and cloud cover. Specifically, sunshine duration is defined as the amount of time usually expressed in hours that direct solar radiation exceeds a certain threshold (usually taken at 120 W m-2). Consequently, this variable can be considered as an excellent proxy measure of solar radiation at interannual and decadal time scales, with the advantage that measurements of this variable were initiated in the late 19th century in different, worldwide, main meteorological stations. Nevertheless, detailed and up-to-date analysis of sunshine duration behavior on global or hemispheric scales are still missing. Thus, starting on September 2010 in the framework of different research projects, we will engage a worldwide compilation of the longest daily or monthly sunshine duration series from the late 19th century until present. Several quality control checks and homogenization methods will be applied to the generated sunshine dataset. The relationship between the more precise downward solar radiation series from the Global Energy Balance Archive (GEBA) and the homogenized sunshine series will be studied in order to reconstruct global and regional solar irradiance at the Earth's surface since the late 19th century. Since clouds are the main cause of interannual and decadal variability of radiation reaching the Earth's surface, as a complement to the long-term sunshine series we will also compile worldwide surface cloudiness observations. With this presentation we seek to encourage the climate community to contribute with their own local datasets to the SunCloud project. The SunCloud Team: M. Wild, Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland

  20. Observational and Dynamical Wave Climatologies. VOS vs Satellite Data

    NASA Astrophysics Data System (ADS)

    Grigorieva, Victoria; Badulin, Sergei; Chernyshova, Anna

    2013-04-01

    The understanding physics of wind-driven waves is crucially important for fundamental science and practical applications. This is why experimental efforts are targeted at both getting reliable information on sea state and elaborating effective tools of the sea wave forecasting. The global Visual Wave Observations and satellite data from the GLOBWAVE project of the European Space Agency are analyzed in the context of these two viewpoints. Within the first "observational" aspect we re-analyze conventional climatologies of all basic wave parameters for the last decades [5]. An alternative "dynamical" climatology is introduced as a tool of prediction of dynamical features of sea waves on global scales. The features of wave dynamics are studied in terms of one-parametric dependencies of wave heights on wave periods following the theoretical concept of self-similar wind-driven seas [3, 1, 4] and recently proposed approach to analysis of Voluntary Observing Ship (VOS) data [2]. Traditional "observational" climatologies based on VOS and satellite data collections demonstrate extremely consistent pictures for significant wave heights and dominant periods. On the other hand, collocated satellite and VOS data show significant differences in wave heights, wind speeds and, especially, in wave periods. Uncertainties of visual wave observations can explain these differences only partially. We see the key reason of this inconsistency in the methods of satellite data processing which are based on formal application of data interpolation methods rather than on up-to-date physics of wind-driven waves. The problem is considered within the alternative climatology approach where dynamical criteria of wave height-to-period linkage are used for retrieving wave periods and constructing physically consistent dynamical climatology. The key dynamical parameter - exponent R of one-parametric dependence Hs ~ TR shows dramatically less pronounced latitudinal dependence as compared to observed Hs

  1. GFDL ARM Project Technical Report: Using ARM Observations to Evaluate Cloud and Convection Parameterizations & Cloud-Convection-Radiation Interactions in the GFDL Atmospheric General Circulation Model

    SciTech Connect

    V. Ramaswamy; L. J. Donner; J-C. Golaz; S. A. Klein

    2010-06-17

    This report briefly summarizes the progress made by ARM postdoctoral fellow, Yanluan Lin, at GFDL during the period from October 2008 to present. Several ARM datasets have been used for GFDL model evaluation, understanding, and improvement. This includes a new ice fall speed parameterization with riming impact and its test in GFDL AM3, evaluation of model cloud and radiation diurnal and seasonal variation using ARM CMBE data, model ice water content evaluation using ARM cirrus data, and coordination of the TWPICE global model intercomparison. The work illustrates the potential and importance of ARM data for GCM evaluation, understanding, and ultimately, improvement of GCM cloud and radiation parameterizations. Future work includes evaluation and improvement of the new dynamicsPDF cloud scheme and aerosol activation in the GFDL model.

  2. Exploiting Open Environmental Data using Linked Data and Cloud Computing: the MELODIES project

    NASA Astrophysics Data System (ADS)

    Blower, Jon; Gonçalves, Pedro; Caumont, Hervé; Koubarakis, Manolis; Perkins, Bethan

    2015-04-01

    The European Open Data Strategy establishes important new principles that ensure that European public sector data will be released at no cost (or marginal cost), in machine-readable, commonly-understood formats, and with liberal licences enabling wide reuse. These data encompass both scientific data about the environment (from Earth Observation and other fields) and other public sector information, including diverse topics such as demographics, health and crime. Many open geospatial datasets (e.g. land use) are already available through the INSPIRE directive and made available through infrastructures such as the Global Earth Observation System of Systems (GEOSS). The intention of the Open Data Strategy is to stimulate the growth of research and value-adding services that build upon these data streams; however, the potential value inherent in open data, and the benefits that can be gained by combining previously-disparate sources of information are only just starting to become understood. The MELODIES project (Maximising the Exploitation of Linked Open Data In Enterprise and Science) is developing eight innovative and sustainable services, based upon Open Data, for users in research, government, industry and the general public in a broad range of societal and environmental benefit areas. MELODIES (http://melodiesproject.eu) is a European FP7 project that is coordinated by the University of Reading and has sixteen partners (including nine SMEs) from eight European countries. It started in November 2013 and will run for three years. The project is therefore in its early stages and therefore we will value the opportunity that this workshop affords to present our plans and interact with the wider Linked Geospatial Data community. The project is developing eight new services[1] covering a range of domains including agriculture, urban ecosystems, land use management, marine information, desertification, crisis management and hydrology. These services will combine Earth

  3. Mars Geoscience Climatology Orbiter (MGCO) extended study: Technical volume

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The FLTSATCOM Earth orbiting communications satellite is a prominent candidate to serve as the Mars Geoscience Climatology Orbiter (MGCO) spacecraft. Major aspects directly applicable are: (1) the incorporation of solid orbit insertion motor; (2) the ability to cruise to Mars in the spin-stabilized mode; (3) ample capability for payload mass and power; (4) attitude control tried to nadir and orbit plane coordinates; (5) exemplary Earth orbital performance record and projected lifetime; and (6) existence of an on-going procurement into the MGCO time period.

  4. A global satellite assisted precipitation climatology

    USGS Publications Warehouse

    Funk, Christopher C.; Verdin, Andrew P.; Michaelsen, Joel C.; Pedreros, Diego; Husak, Gregory J.; Peterson, P.

    2015-01-01

    Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti) are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high resolution (0.05°) global precipitation climatologies that perform reasonably well in data sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology, the Climate

  5. A global satellite-assisted precipitation climatology

    NASA Astrophysics Data System (ADS)

    Funk, C.; Verdin, A.; Michaelsen, J.; Peterson, P.; Pedreros, D.; Husak, G.

    2015-10-01

    Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti) are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high-resolution (0.05°) global precipitation climatologies that perform reasonably well in data-sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology, the Climate

  6. New dynamic NNORSY ozone profile climatology

    NASA Astrophysics Data System (ADS)

    Kaifel, A. K.; Felder, M.; Declercq, C.; Lambert, J.-C.

    2012-01-01

    Climatological ozone profile data are widely used as a-priori information for total ozone using DOAS type retrievals as well as for ozone profile retrieval using optimal estimation, for data assimilation or evaluation of 3-D chemistry-transport models and a lot of other applications in atmospheric sciences and remote sensing. For most applications it is important that the climatology represents not only long term mean values but also the links between ozone and dynamic input parameters. These dynamic input parameters should be easily accessible from auxiliary datasets or easily measureable, and obviously should have a high correlation with ozone. For ozone profile these parameters are mainly total ozone column and temperature profile data. This was the outcome of a user consultation carried out in the framework of developing a new, dynamic ozone profile climatology. The new ozone profile climatology is based on the Neural Network Ozone Retrieval System (NNORSY) widely used for ozone profile retrieval from UV and IR satellite sounder data. NNORSY allows implicit modelling of any non-linear correspondence between input parameters (predictors) and ozone profile target vector. This paper presents the approach, setup and validation of a new family of ozone profile climatologies with static as well as dynamic input parameters (total ozone and temperature profile). The neural network training relies on ozone profile measurement data of well known quality provided by ground based (ozonesondes) and satellite based (SAGE II, HALOE, and POAM-III) measurements over the years 1995-2007. In total, four different combinations (modes) for input parameters (date, geolocation, total ozone column and temperature profile) are available. The geophysical validation spans from pole to pole using independent ozonesonde, lidar and satellite data (ACE-FTS, AURA-MLS) for individual and time series comparisons as well as for analysing the vertical and meridian structure of different modes of

  7. The Adaptive Ecosystem Climatology (AEC): Implementation

    NASA Astrophysics Data System (ADS)

    Penta, B.; deRada, S.; Grüss, A.; Gould, R. W., Jr.; McCarthy, S.

    2016-02-01

    Ecological forecasting used in decision-making for conservation and resource management frequently relies upon climatologies, remote sensing observations, or models. Each of these elements has inherent limitations and errors. The Adaptive Ecosystem Climatology (AEC) is a flexible, on-line tool for ecoforecasting applications; it melds in-situ observations, satellite data, and output from a state-of-the-art, data assimilative, coupled bio-optical-physical ocean model system. AEC mitigates the shortcomings of these individual components and combines their strengths to enhance decision-making tools for conservation and natural resource management. The system is implemented on the NOAA Ocean NOMADS web portal. Visualization and analysis tools are available on this portal, climatologies can be displayed, and data files can be downloaded, for direct input into external management models (such as ecosystem, oil trajectory, or fisheries models) and other ecoforecasting applications. Ocean properties available from the coupled model and satellite imagery include primary ecosystem components (temperature, salinity, sea surface height, currents, plankton, and chlorophyll). We have built a three-dimensional, dynamically balanced, gridded, static climatology for each calendar day, employing data for the period 1980-2012. Using the static climatology as a background `first guess', recent observations (satellite or in situ) are assimilated to adjust the climatology toward current conditions, to provide updated, representative fields (adaptive climatology). AEC can be used to examine mean conditions, to analyze available observations, or as input and boundary conditions to many types of models (conceptual, statistical, water-quality, biogeochemical, production, mass-balance energy flow models, individual-based, and multispecies models with explicit species interaction terms, sophisticated end-to-end models, etc.). We demonstrate the utility of AEC using an individual

  8. Double-moment cloud microphysics scheme for the deep convection parameterization in the GFDL AM3

    NASA Astrophysics Data System (ADS)

    Belochitski, A.; Donner, L.

    2014-12-01

    A double-moment cloud microphysical scheme originally developed by Morrision and Gettelman (2008) for the stratiform clouds and later adopted for the deep convection by Song and Zhang (2011) has been implemented in to the Geophysical Fluid Dynamics Laboratory's atmospheric general circulation model AM3. The scheme treats cloud drop, cloud ice, rain, and snow number concentrations and mixing ratios as diagnostic variables and incorporates processes of autoconversion, self-collection, collection between hydrometeor species, sedimentation, ice nucleation, drop activation, homogeneous and heterogeneous freezing, and the Bergeron-Findeisen process. Such detailed representation of microphysical processes makes the scheme suitable for studying the interactions between aerosols and convection, as well as aerosols' indirect effects on clouds and their roles in climate change. The scheme is first tested in the single column version of the GFDL AM3 using forcing data obtained at the U.S. Department of Energy Atmospheric Radiation Measurment project's Southern Great Planes site. Scheme's impact on SCM simulations is discussed. As the next step, runs of the full atmospheric GCM incorporating the new parameterization are compared to the unmodified version of GFDL AM3. Global climatological fields and their variability are contrasted with those of the original version of the GCM. Impact on cloud radiative forcing and climate sensitivity is investigated.

  9. Trends in Ocean Irradiance using a Radiative Model Forced with Terra Aerosols and Clouds

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Casey, Nancy; Romanou, Anastasia

    2010-01-01

    Aerosol and cloud information from MODIS on Terra provide enhanced capability to understand surface irradiance over the oceans and its variability. These relationships can be important for ocean biology and carbon cycles. An established radiative transfer model, the Ocean-Atmosphere Spectral Irradiance Model (OASIM) is used to describe ocean irradiance variability on seasonal to decadal time scales. The model is forced with information on aerosols and clouds from the MODIS sensor on Terra and Aqua. A 7-year record (2000-2006) showed no trends in global ocean surface irradiance or photosynthetic available irradiance (PAR). There were significant (P<0.05) negative trends in the Mediterranean Sea, tropical Pacific) and tropical Indian Oceans, of -7.0, -5.0 and -2.7 W/sq m respectively. Global interannual variability was also modest. Regional interannual variability was quite large in some ocean basins, where monthly excursions from climatology were often >20 W/sq m. The trends using MODIS data contrast with results from OASIM using liquid water path estimates from the International Satellite Cloud Climatology Project (ISCCP). Here, a global trend of -2 W/sq m was observed, largely dues to a large negative trend in the Antarctic -12 W/sq m. These results suggest the importance of the choice of liquid water path data sets in assessments of medium-length trends in ocean surface irradiance. The choices also impact the evaluation of changes in ocean biogeochemistry.

  10. An analysis of high cloud variability: imprints from the El Niño-Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Li, King-Fai; Su, Hui; Mak, Sze-Ning; Chang, Tiffany M.; Jiang, Jonathan H.; Norris, Joel R.; Yung, Yuk L.

    2017-01-01

    Using data from the International Satellite Cloud Climatology Project (ISCCP), we examine how near-global (60°N-60°S) high cloud fraction varies over time in the past three decades. Our focus is on identifying dominant modes of variability and associated spatial patterns, and how they are related to sea surface temperature. By performing the principal component analysis, we find that the first two principal modes of high cloud distribution show strong imprints of the two types of El Niño-Southern Oscillation (ENSO)—the canonical ENSO and the ENSO Modoki. Comparisons between ISCCP data and 14 models from the Atmospheric Model Intercomparison Project Phase 5 (AMIP5) show that models simulate the spatial pattern and the temporal variations of high cloud fraction associated with the canonical ENSO very well but the magnitudes of the canonical ENSO vary among the models. Furthermore, the multi-model mean of the second principal mode in the AMIP5 simulations appears to capture the temporal behavior of the second mode but individual AMIP5 models show large discrepancies in capturing observed temporal variations. A new metric, defined by the relative variances of the first two principal components, suggests that most of the AMIP5 models overestimate the second principal mode of high clouds.

  11. Gridded Croatian climatology for 1961-1990

    NASA Astrophysics Data System (ADS)

    Perčec Tadić, Melita

    2010-10-01

    In climatology, one of the most important pieces of information about the climate of a place or a region is information about the Climatological Normals (CLINO)—the average values of meteorological elements for a 30-year period. This kind of information usually comes in tables and is available for different observation sites from national meteorological services or from World Meteorological Organisation publications. The key issue, then, becomes how to interpolate these values over the entire area of interest to get reliable and accurate estimates (maps) of climatic elements. Here, the regression kriging framework has been applied for mapping of 20 climatological parameters for the 1961-1990 period for the 56,594 km2 of Croatian territory, with a resolution of 1 km. In total, 152 main and climatological and 567 precipitation-measuring stations have been used in the analysis. Extensive pre-processing of metadata on station co-ordinates has been done, as well as completion of missing monthly averages. The final results are 20 climatological maps available in high resolution together with error maps and accuracy assessment measures.

  12. SPARC Intercomparison of Middle Atmosphere Climatologies

    NASA Technical Reports Server (NTRS)

    Randel, William; Fleming, Eric; Geller, Marvin; Hamilton, Kevin; Karoly, David; Ortland, Dave; Pawson, Steve; Swinbank, Richard; Udelhofen, Petra

    2002-01-01

    This atlas presents detailed incomparisons of several climatological wind and temperature data sets which cover the middle atmosphere (over altitudes approx. 10-80 km). A number of middle atmosphere climatologies have been developed in the research community based on a variety of meteorological analyses and satellite data sets. Here we present comparisons between these climatological data sets for a number of basic circulation statistics, such as zonal mean temperature, winds and eddy flux statistics. Special attention is focused on tropical winds and temperatures, where large differences exist among separate analyses. We also include comparisons between the global climatologies and historical rocketsonde wind and temperature measurements, and also with more recent lidar temperature data. These comparisons highlight differences and uncertainties in contemporary middle atmosphere data sets, and allow biases in particular analyses to be isolated. In addition, a brief atlas of zonal mean temperature and wind statistics is provided to highlight data availability and as a quick-look reference. This technical report is intended as a companion to the climatological data sets held in archive at the SPARC Data Center (http://www.sparc.sunysb.edu).

  13. High Resolution Cloud Microphysics and Radiation Studies

    DTIC Science & Technology

    2011-06-16

    characteristics of mid level altocumulus clouds and upper level visible and subvisual cirrus clouds The MPL lidar provided information about the temporal...balloon, lidar, and radar study of cirrus and altocumulus clouds to further investigate the presence of multi- cloud and nearly cloud -free layers...data set of the clouds and thermodynanuc structure to build a mesoscale and LF.S test-bed for cirrus and altocumulus cloud layers. The project was

  14. Snow and Ice Climatology of the Western United States and Alaska from MODIS

    NASA Astrophysics Data System (ADS)

    Rittger, K. E.; Painter, T. H.; Mattmann, C. A.; Seidel, F. C.; Burgess, A.; Brodzik, M.

    2013-12-01

    The climate and hydroclimate of the Western US and Alaska are tightly coupled to their snow and ice cover. The Western US depends on mountain snowmelt for the majority of its water supply to agriculture, industrial and urban use, hydroelectric generation, and recreation, all driven by increasing population and demand. Alaskan snow and glacier cover modulate regional climate and, as with the Western US, dominate water supply and hydroelectric generation in much of the state. Projections of climate change in the Western US and Alaska suggest that the most pronounced impacts will include reductions of mountain snow and ice cover, earlier runoff, and a greater fraction of rain instead of snow. We establish a snow and ice climatology of the Western US and Alaska using physically based MODIS Snow Covered Area and Grain size model (MODSCAG) for fractional snow cover, the MODIS Dust Radiative Forcing in Snow model (MODDRFS) for radiative forcing by light absorbing impurities in snow, and the MODIS Permanent Ice model (MODICE) for annual minimum exposed snow. MODSCAG and MODDRFS use EOS MOD09GA historical reflectance data (2000-2012) to provide daily and 8-day composites and near real time products since the beginning of 2013, themselves ultimately composited to 8-day products. The compositing method considers sensor-viewing geometry, solar illumination, clouds, cloud shadows, aerosols and noisy detectors in order to select the best pixel for an 8-day period. The MODICE annual minimum exposed snow and ice product uses the daily time series of fractional snow and ice from MODSCAG to generate annual maps. With this project we have established an ongoing, national-scale, consistent and replicable approach to assessing current and projected climate impacts and climate-related risk in the context of other stressors. We analyze the products in the Northwest, Southwest, and Alaska/Arctic regions of the National Climate Assessment for the last decade, the nation's hottest on record

  15. HelioFTH: combining cloud index principles and aggregated rating for cloud masking using infrared observations from geostationary satellites

    NASA Astrophysics Data System (ADS)

    Dürr, B.; Schröder, M.; Stöckli, R.; Posselt, R.

    2013-08-01

    In this paper a cloud mask and cloud fractional coverage (CFC) retrieval scheme called HelioFTH is presented. The algorithm is self-calibrating and relies on infrared (IR) window-channel observations only. It needs no input from numerical weather prediction (NWP) or radiative transfer models, nor from other satellite platforms. The scheme is applicable to the full temporal and spatial resolution of the Meteosat Visible and InfraRed Imager (MVIRI) and the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensors. The main focus is laid on the separation of middle- and high-level cloud coverage (HCC) from low-level clouds based on an internal cloud-top pressure (CTP) product. CFC retrieval employs a IR-only cloud mask based on an aggregated rating scheme. CTP retrieval is based on a Heliosat-like cloud index for the MVIRI IR channel. CFC from HelioFTH, the International Satellite Cloud Climatology Project (ISCCP) DX and the Satellite Application Facility on Climate Monitoring (CM SAF) were validated with CFC from the Baseline Surface Radiation Network (BSRN) and the Alpine Surface Radiation Budget (ASRB) network. HelioFTH CFC differs by not more than 5-10% from CM SAF CFC but it is higher than ISCCP-DX CFC. In particular the conditional probability to detect cloud-free pixels with HelioFTH is raised by about 35% compared to ISCCP-DX. The HelioFTH CFC is able to reproduce the day-to-day variability observed at the surface. Also, the HelioFTH HCC was inter-compared to CM SAF and ISCCP-DX over different regions and stations. The probability of false detection of cloud-free HCC pixels is in the same order as ISCCP-DX compared to the CM SAF HCC product over the full-disk area. HelioFTH could be used for generating an independent climate data record of cloud physical properties once its consistency and homogeneity is validated for the full Meteosat time series.

  16. Millimeter-Wave Radar Field Measurements and Inversion of Cloud Parameters for the 1999 Mt. Washington Icing Sensors Project

    NASA Technical Reports Server (NTRS)

    Pazmany, Andrew L.; Reehorst, Andrew (Technical Monitor)

    2001-01-01

    The Mount Washington Icing Sensors Project (MWISP) was a multi-investigator experiment with participants from Quadrant Engineering, NOAA Environmental Technology Laboratory (NOAA/ETL), the Microwave Remote Sensing Laboratory (MIRSL) of the University of Massachusetts (UMass), and others. Radar systems from UMass and NOAA/ETL were used to measure X-, Ka-, and W-band backscatter data from the base of Mt. Washington, while simultaneous in-situ particle measurements were made from aircraft and from the observatory at the summit. This report presents range and time profiles of liquid water content and particle size parameters derived from range profiles of radar reflectivity as measured at X-, Ka-, and W-band (9.3, 33.1, and 94.9 GHz) using an artificial neural network inversion algorithm. In this report, we provide a brief description of the experiment configuration, radar systems, and a review of the artificial neural network used to extract cloud parameters from the radar data. Time histories of liquid water content (LWC), mean volume diameter (MVD) and mean Z diameter (MZD) are plotted at 300 m range intervals for slant ranges between 1.1 and 4 km. Appendix A provides details on the extraction of radar reflectivity from measured radar power, and Appendix B provides summary logs of the weather conditions for each day in which we processed data.

  17. Southern Clouds

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03026 Southern Clouds

    This image shows a system of clouds just off the margin of the South Polar cap. Taken during the summer season, these clouds contain both water-ice and dust.

    Image information: VIS instrument. Latitude 80.2S, Longitude 57.6E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  18. Linear Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03667 Linear Clouds

    These clouds are located near the edge of the south polar region. The cloud tops are the puffy white features in the bottom half of the image.

    Image information: VIS instrument. Latitude -80.1N, Longitude 52.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  19. Using Webgis and Cloud Tools to Promote Cultural Heritage Dissemination: the Historic up Project

    NASA Astrophysics Data System (ADS)

    Tommasi, A.; Cefalo, R.; Zardini, F.; Nicolaucig, M.

    2017-05-01

    On the occasion of the First World War centennial, GeoSNav Lab (Geodesy and Satellite Navigation Laboratory), Department of Engineering and Architecture, University of Trieste, Italy, in coooperation with Radici&Futuro Association, Trieste, Italy, carried out an educational Project named "Historic Up" involving a group of students from "F. Petrarca" High School of Trieste, Italy. The main goal of the project is to make available to students of Middle and High Schools a set of historical and cultural contents in a simple and immediate way, through the production of a virtual and interactive tour following the event that caused the burst of the First World War: the assassination of Franz Ferdinand and his wife Sofia in Sarajevo occurred on June 28, 1914. A set of Google Apps was used, including Google Earth, Maps, Tour Builder, Street View, Gmail, Drive, and Docs. The Authors instructed the students about software and team-working and supported them along the research. After being checked, all the historical and geographic data have been uploaded on a Google Tour Builder to create a sequence of historical checkpoints. Each checkpoint has texts, pictures and videos that connect the tour-users to 1914. Moreover, GeoSNaV Lab researchers produced a KML (Keyhole Markup Language) file, formed by several polylines and points, representing the itinerary of the funeral procession that has been superimposed on ad-hoc georeferenced historical maps. This tour, freely available online, starts with the arrival of the royals, on June 28th 1914, and follows the couple along the events, from the assassination to the burial in Arstetten (Austria), including their passages through Trieste (Italy), Ljubljana (Slovenia), Graz and Wien (Austria).

  20. Hydrologic and climatologic data, 1966, Salt Lake County, Utah

    USGS Publications Warehouse

    Hely, A.G.; Mower, Reed W.; Horr, C.A.

    1967-01-01

    An investigation of the water resources of Salt Lake County, Utah, was undertaken by the Water Resources Division of the U.S. Geological Survey in July 1963. This investigation is a cooperative project financed equally by the State of Utah and the Federal Government in accordance with an agreement between the State Engineer and the Geological Survey. The Utah Water and Power Board, Utah Fish and Game Commission, Salt Lake County Water Conservancy District, Metropolitan Water District of Salt Lake City, Salt Lake County, Kennecott Copper Corporation, Utah Power and Light Company, Salt Lake City Chamber of Commerce, and the Central Utah Water Conservancy District contributed funds to the State Engineer's office toward support of the project.The investigation encompasses the collection and interpretation of a large variety of climatologic, hydrologic, and geologic data in and near Salt Lake County. Utah Basic-Data Releases 11 and 12 contain data collected through 1965. This release contains climatologic and surface-water data for the 1966 water year (October 1965 to September 1966) and groundwater data collected during the 1966 calendar year. Similar annual releases will contain data collected during the remainder of the investigation, and interpretive reports will be prepared as the investigation proceeds. Organizations that furnished data are acknowledged in station descriptions and footnotes to tables.

  1. Hydrologic and climatologic data, 1965, Salt Lake County, Utah

    USGS Publications Warehouse

    Iorns, W.V.; Mower, Reed W.; Horr, C.A.

    1966-01-01

    An investigation of the water resources of Salt Lake County, Utah, was undertaken by the Water Resources Division of the U.S. Geological Survey in July 1963. This investigation is a cooperative project financed equally by the State of Utah and the Federal Government in accordance with an agreement between the State Engineer and the Geological Survey. The Utah Water and Power Board, Utah Fish and Game Commission, Salt Lake County Water Conservancy District, Metropolitan Water District of Salt Lake City, Salt Lake County, Kennecott Copper Corporation, Utah Power and Light Company, Salt Lake City Chamber of Commerce, and the Central Utah Water Conservancy District. contributed funds to the State Engineer's office toward support of the project.The investigation encompasses the collection and interpretation of a large variety of climatologic, hydrologic, and geologic data in and near Salt Lake County. Utah Basic-Data Release No. 11 contains data collected through 1964. This release contains climatologic and surface-water data for the 1965 water year (October 1964 to September 1965) and ground-water data collected during the 1965 calendar year. Similar annual releases will contain data collected during the remainder of the investigation, and interpretive reports will be prepared as the investigation proceeds. Organizations that furnished data are acknowledged in station descriptions and footnotes to tables.

  2. A model of the tropical Pacific sea surface temperature climatology

    NASA Technical Reports Server (NTRS)

    Seager, Richard; Zebiak, Stephen E.; Cane, Mark A.

    1988-01-01

    A model for the climatological mean sea surface temperature (SST) of the tropical Pacific Ocean is developed. The upper ocean response is computed using a time dependent, linear, reduced gravity model, with the addition of a constant depth frictional surface layer. The full three-dimensional temperature equation and a surface heat flux parameterization that requires specification of only wind speed and total cloud cover are used to evaluate the SST. Specification of atmospheric parameters, such as air temperature and humidity, over which the ocean has direct influence, is avoided. The model simulates the major features of the observed tropical Pacific SST. The seasonal evolution of these features is generally captured by the model. Analysis of the results demonstrates the control the ocean has over the surface heat flux from ocean to atmosphere and the crucial role that dynamics play in determining the mean SST in the equatorial Pacific. The sensitivity of the model to perturbations in the surface heat flux, cloud cover specification, diffusivity, and mixed layer depth is discussed.

  3. A model of the tropical Pacific sea surface temperature climatology

    NASA Technical Reports Server (NTRS)

    Seager, Richard; Zebiak, Stephen E.; Cane, Mark A.

    1988-01-01

    A model for the climatological mean sea surface temperature (SST) of the tropical Pacific Ocean is developed. The upper ocean response is computed using a time dependent, linear, reduced gravity model, with the addition of a constant depth frictional surface layer. The full three-dimensional temperature equation and a surface heat flux parameterization that requires specification of only wind speed and total cloud cover are used to evaluate the SST. Specification of atmospheric parameters, such as air temperature and humidity, over which the ocean has direct influence, is avoided. The model simulates the major features of the observed tropical Pacific SST. The seasonal evolution of these features is generally captured by the model. Analysis of the results demonstrates the control the ocean has over the surface heat flux from ocean to atmosphere and the crucial role that dynamics play in determining the mean SST in the equatorial Pacific. The sensitivity of the model to perturbations in the surface heat flux, cloud cover specification, diffusivity, and mixed layer depth is discussed.

  4. Radiative Effect of Clouds on Tropospheric Chemistry in a Global Three-Dimensional Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Liu, Hongyu; Crawford, James H.; Pierce, Robert B.; Norris, Peter; Platnick, Steven E.; Chen, Gao; Logan, Jennifer A.; Yantosca, Robert M.; Evans, Mat J.; Kittaka, Chieko; hide

    2006-01-01

    Clouds exert an important influence on tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies (J-values). We assess the radiative effect of clouds on photolysis frequencies and key oxidants in the troposphere with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations from the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA Global Modeling and Assimilation Office (GMAO). We focus on the year of 2001 with the GEOS-3 meteorological observations. Photolysis frequencies are calculated using the Fast-J radiative transfer algorithm. The GEOS-3 global cloud optical depth and cloud fraction are evaluated and generally consistent with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP). Results using the linear assumption, which assumes linear scaling of cloud optical depth with cloud fraction in a grid box, show global mean OH concentrations generally increase by less than 6% because of the radiative effect of clouds. The OH distribution shows much larger changes (with maximum decrease of approx.20% near the surface), reflecting the opposite effects of enhanced (weakened) photochemistry above (below) clouds. The global mean photolysis frequencies for J[O1D] and J[NO2] in the troposphere change by less than 5% because of clouds; global mean O3 concentrations in the troposphere increase by less than 5%. This study shows tropical upper tropospheric O3 to be less sensitive to the radiative effect of clouds than previously reported (approx.5% versus approx.20-30%). These results emphasize that the dominant effect of clouds is to influence the vertical redistribution of the intensity of photochemical activity while global average effects remain modest, again contrasting with previous studies. Differing vertical distributions

  5. Radiative Effect of Clouds on Tropospheric Chemistry in a Global Three-Dimensional Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Liu, Hongyu; Crawford, James H.; Pierce, Robert B.; Norris, Peter; Platnick, Steven E.; Chen, Gao; Logan, Jennifer A.; Yantosca, Robert M.; Evans, Mat J.; Kittaka, Chieko; Feng, Yan; Tie, Xuexi

    2006-01-01

    Clouds exert an important influence on tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies (J-values). We assess the radiative effect of clouds on photolysis frequencies and key oxidants in the troposphere with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations from the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA Global Modeling and Assimilation Office (GMAO). We focus on the year of 2001 with the GEOS-3 meteorological observations. Photolysis frequencies are calculated using the Fast-J radiative transfer algorithm. The GEOS-3 global cloud optical depth and cloud fraction are evaluated and generally consistent with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP). Results using the linear assumption, which assumes linear scaling of cloud optical depth with cloud fraction in a grid box, show global mean OH concentrations generally increase by less than 6% because of the radiative effect of clouds. The OH distribution shows much larger changes (with maximum decrease of approx.20% near the surface), reflecting the opposite effects of enhanced (weakened) photochemistry above (below) clouds. The global mean photolysis frequencies for J[O1D] and J[NO2] in the troposphere change by less than 5% because of clouds; global mean O3 concentrations in the troposphere increase by less than 5%. This study shows tropical upper tropospheric O3 to be less sensitive to the radiative effect of clouds than previously reported (approx.5% versus approx.20-30%). These results emphasize that the dominant effect of clouds is to influence the vertical redistribution of the intensity of photochemical activity while global average effects remain modest, again contrasting with previous studies. Differing vertical distributions

  6. The Roles of El Nino and Solar Forcing on Cloud Cover

    NASA Astrophysics Data System (ADS)

    Rohde, R. A.; Levine, J.; Muller, R. A.

    2003-12-01

    Although cloud cover has a very strong effect on climate, its behavior is so poorly understood that its role is frequently neglected. A potential breakthrough occurred with initial reports that cloud cover could be driven by variations in cosmic rays (H. Svensmark & E. Friis-Christensen, J. Atmos. Solar-Terr. Phys. v. 59, n. 11, pp 1225-32, 1997, and N.D. Marsh & H. Svensmark, Space Sci. Rev., pp 1-16, 2000). In this paper we report a detailed analysis of recently extended data now available from the International Satellite Cloud Climatology Project. In a surprise, we find that the major driving force for cloud cover is ENSO (El Nino / Southern Oscillation). In addition, we do find a weak but significant response to solar forcing; however, in contradiction to the previous reports, we find no stronger relationship to cosmic rays than to other solar parameters. For the majority of the 23 cloud types available to us, interannual variability is dominated by changes that follow the NINO3 index of Pacific sea surface temperatures. In particular, increases in high-altitude and vertically extensive cloud cover are observed to follow the motions of warm water throughout the El Nino cycle. Even far from the Pacific, many cloud cover changes are observed to correlate with El Nino, and these data provide a new and previously unexplored tool for understanding the global nature and influence of the El Nino / Southern Oscillation. In contrast, solar forcing of cloud cover is observed in, at most, a few cloud types. Only in the cloud type emphasized by Svensmark, low-altitude clouds detected in the infrared, does the dominant mode of interannual variability make a good match with solar forcing. The extended cloud record provides continued support for solar forcing of this cloud type; however, unlike Svensmark, we find no empirical reason to prefer cosmic ray flux as the forcing mechanism over any other type of solar cycle variation (e.g. irradiance or UV flux changes). Our

  7. Cloud Inhomogeneity from MODIS

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cahalan, Robert F.

    2004-01-01

    Two full months (July 2003 and January 2004) of MODIS Atmosphere Level-3 data from the Terra and Aqua satellites are analyzed in order to characterize the horizontal variability of cloud optical thickness and water path at global scales. Various options to derive cloud variability parameters are discussed. The climatology of cloud inhomogeneity is built by first calculating daily parameter values at spatial scales of l degree x 1 degree, and then at zonal and global scales, followed by averaging over monthly time scales. Geographical, diurnal, and seasonal changes of inhomogeneity parameters are examined separately for the two cloud phases, and separately over land and ocean. We find that cloud inhomogeneity is weaker in summer than in winter, weaker over land than ocean for liquid clouds, weaker for local morning than local afternoon, about the same for liquid and ice clouds on a global scale, but with wider probability distribution functions (PDFs) and larger latitudinal variations for ice, and relatively insensitive to whether water path or optical thickness products are used. Typical mean values at hemispheric and global scales of the inhomogeneity parameter nu (roughly the mean over the standard deviation of water path or optical thickness), range from approximately 2.5 to 3, while for the inhomogeneity parameter chi (the ratio of the logarithmic to linear mean) from approximately 0.7 to 0.8. Values of chi for zonal averages can occasionally fall below 0.6 and for individual gridpoints below 0.5. Our results demonstrate that MODIS is capable of revealing significant fluctuations in cloud horizontal inhomogenity and stress the need to model their global radiative effect in future studies.

  8. A time variable model of Earth's albedo. [for climatology studies and interpretation of satellite data

    NASA Technical Reports Server (NTRS)

    Bartman, F. L.

    1980-01-01

    A time variable model of Earth's albedo was prepared for use in climate studies and as an aid to the interpretation of satellite Earth radiation budget data. The features of the model include: a 10 deg latitude 10 deg longitude grid for numerical integration, surface albedo specified at 1 month intervals, calculation of zenith angle effect for surface albedo and of the additional effect of the atmosphere on the albedo. Percent cloud cover is specified for 29 different climatological cloud type regions at 8 times of the day for 12 months of the year. Cloud albedos were specified for each of the cloud climatological types. Diurnal and monthly variations of this model are described and results are compared with a model which is based on satellite measurements. A computer program was also written for use in studying the sampling effects in satellite radiation budget measurements. An example of the results of calculations with this program are compared with a previous study of the sampling effects. This program for satellite orbit characteristics is to be combined with the time-variable albedo model for further study of the sampling problem.

  9. Search Cloud

    MedlinePlus

    ... this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this page, ... chest pa and lateral Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  10. Hanford Site Climatological Data Summary 1999 with Historical Data

    SciTech Connect

    Hoitink, Dana J.; Burk, Kenneth W.; Ramsdell, James V.

    2000-05-11

    This document presents the climatological data measured at the Hanford Site for claendar year 1999. The information contained includes updated historical climatologies for temperature, precipitation, normal and extreme values of temperature and precipitaion and other meteorological parameters.

  11. Windowed and Wavelet Analysis of Marine Stratocumulus Cloud Inhomogeneity

    NASA Technical Reports Server (NTRS)

    Gollmer, Steven M.; Harshvardhan; Cahalan, Robert F.; Snider, Jack B.

    1995-01-01

    To improve radiative transfer calculations for inhomogeneous clouds, a consistent means of modeling inhomogeneity is needed. One current method of modeling cloud inhomogeneity is through the use of fractal parameters. This method is based on the supposition that cloud inhomogeneity over a large range of scales is related. An analysis technique named wavelet analysis provides a means of studying the multiscale nature of cloud inhomogeneity. In this paper, the authors discuss the analysis and modeling of cloud inhomogeneity through the use of wavelet analysis. Wavelet analysis as well as other windowed analysis techniques are used to study liquid water path (LWP) measurements obtained during the marine stratocumulus phase of the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment. Statistics obtained using analysis windows, which are translated to span the LWP dataset, are used to study the local (small scale) properties of the cloud field as well as their time dependence. The LWP data are transformed onto an orthogonal wavelet basis that represents the data as a number of times series. Each of these time series lies within a frequency band and has a mean frequency that is half the frequency of the previous band. Wavelet analysis combined with translated analysis windows reveals that the local standard deviation of each frequency band is correlated with the local standard deviation of the other frequency bands. The ratio between the standard deviation of adjacent frequency bands is 0.9 and remains constant with respect to time. This ratio defined as the variance coupling parameter is applicable to all of the frequency bands studied and appears to be related to the slope of the data's power spectrum. Similar analyses are performed on two cloud inhomogeneity models, which use fractal-based concepts to introduce inhomogeneity into a uniform cloud field. The bounded cascade model does this by iteratively redistributing LWP at each scale

  12. Investigation of cloud properties using a Raman lidar

    NASA Astrophysics Data System (ADS)

    Whiteman, David Neil

    the radiance seen by satellite and that cirrus clouds with optical depths as low as 0.005 can influence satellite radiances. Using the International Satellite Cloud Climatology Project cirrus cloud detection thresholds implies up to a 40% high bias in retrieved total precipitable water due to undetected cirrus clouds. This result has potentially important consequences for the global database of precipitable water determined using IR satellite measurements.

  13. A Characterization of Cirrus Cloud Properties That Affect Laser Propagation

    DTIC Science & Technology

    2008-05-01

    13. SUPPLEMENTARY NOTES - Reprinted from Journal of Applied Meteorology and Climatology, Vol. 47, pp 1322 -1336 14. ABSTRACT Future high-altitude...UNCL UNL 10 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std Z3918 AFRL-RV-HA-TR-2008-1050 1322 JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY VOIIt...retrieved from actual n bo t and to p atindicers The lasermmotha d topmost cloud c mputational layers. The l s r path cirrus measurements are used to

  14. The Savannah River Technology Center Research and Development Climatology Center

    SciTech Connect

    Kurzeja, R.J.

    1995-12-31

    The Environmental Technology Section (ETS) of the Savannah River Technology Center (SRTC) built and has operated the Climatology Site (CS) for almost 10 years. The Climatology Site provides a wide variety of meteorological support functions for Savannah River Site (SRS) operations and research. This document describes the Climatology Site facility to familiarize present and potential users with its capabilities.

  15. Influence of Small-Scale Drop Size Variability on the Estimation of Cloud Optical Properties

    NASA Astrophysics Data System (ADS)

    Knyazikhin, Y.; Marshak, A.; Wiscombe, W. J.; Martonchik, J. V.

    2004-05-01

    Most of the existing cloud radiation models and conventional techniques of data processing assume that the mean number of drops with a given radius varies proportionally to volume. The analysis of microphysical data on liquid water drop sizes acquired during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE), July 1987, and the Atmosphere Radiation Measurements (ARM) Cloud Intensive Operational Period (IOP), March, 2000, shows that, for sufficiently small volumes, the number is proportional to the drop size dependent power of the volume. The drop size dependent coefficient of proportionality, or a generalized drop concentration, and the exponent are determined solely by the smallest sampling volume; they are independent of the volume drops occupy and differentiate spatial distributions of drops with different sizes. For abundant small drops (r > 14 μm) present, the exponent is 1 as assumed in the conventional approach. However, for rarer large drops (r > 14 μm), the exponents fall below unity for scales between the smallest sampling volume and a "saturation" scale. At these scales, therefore, the mean number of large drops decreases with volume at a slower rate than the conventional approach assumes, suggesting more large drops at small scales than conventional models account for; their impact is consequently underestimated. The analysis presented here indicates that depending on cloud size, the neglect of small-scale drop size variability can result in a systematic underestimation of cloud horizontal optical path.

  16. Observed Land Impacts on Clouds, Water Vapor, and Rainfall at Continental Scales

    NASA Technical Reports Server (NTRS)

    Jin, Menglin; King, Michael D.

    2005-01-01

    How do the continents affect large-scale hydrological cycles? How important can one continent be to the climate system? To address these questions, 4-years of National Aeronautics and Space Administration (NASA) Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations, Tropical Rainfall Measuring Mission (TRMM) observations, and the Global Precipitation Climatology Project (GPCP) global precipitation analysis, were used to assess the land impacts on clouds, rainfall, and water vapor at continental scales. At these scales, the observations illustrate that continents are integrated regions that enhance the seasonality of atmospheric and surface hydrological parameters. Specifically, the continents of Eurasia and North America enhance the seasonality of cloud optical thickness, cirrus fraction, rainfall, and water vapor. Over land, both liquid water and ice cloud effective radii are smaller than over oceans primarily because land has more aerosol particles. In addition, different continents have similar impacts on hydrological variables in terms of seasonality, but differ in magnitude. For example, in winter, North America and Eurasia increase cloud optical thickness to 17.5 and 16, respectively, while in summer, Eurasia has much smaller cloud optical thicknesses than North America. Such different land impacts are determined by each continent s geographical condition, land cover, and land use. These new understandings help further address the land-ocean contrasts on global climate, help validate global climate model simulated land-atmosphere interactions, and help interpret climate change over land.

  17. Hydrologic and climatologic data, 1967, Salt Lake County, Utah

    USGS Publications Warehouse

    Hely, A.G.; Mower, Reed W.; Horr, C.A.

    1968-01-01

    An investigation of the water resources of Salt Lake County, Utah, was undertaken by the Water Resources Division of the U.S. Geological Survey in July 1963. This investigation is a cooperative project financed chiefly by equal contributions of the State of Utah and the Federal Government in accordance with an agreement between the Division of Water Rights, Utah Department of Natural Resources, and the Geological Survey. The investigation was financed during the period covered by this report by the following organizations: Utah Division of Water Rights (formerly State Engineer), Utah Division of Water Resources (formerly Water and Power Board), Salt Lake County, Salt Lake County Water Conservancy District, Central Utah Water Conservancy District, Metropolitan Water District of Salt Lake City, City of Murray, Granger-Hunter Improvement District, Taylorsville-Bennion Improvement District, Holladay Water Company, Magna Water and Sewer District, U.S. Bureau of Reclamation, U.S. Geological Survey.The investigation encompasses the collection and interpretation of a large variety of climatologic, hydrologic, and geologic data in and near Salt Lake County. Utah Basic-Data Releases 11-13 contain data collected through 1966. This release contains climatologic and surfacewater data for the 1967 water year (October 1966 to September 1967) and ground-water data collected during the 1967 calendar year. A similar annual release will contain data collected during the remainder of the investigation, and interpretive reports will be prepared as the investigation proceeds. Organizations that furnished data are acknowledged in station descriptions and footnotes to tables.

  18. Hydrologic and climatologic data, 1968, Salt Lake County, Utah

    USGS Publications Warehouse

    1969-01-01

    An investigation of the water resources of Salt Lake County, Utah, was undertaken by the Water Resources Division of the U.S. Geological Survey in July 1963. This investigation is a cooperative project financed chiefly by equal contributions of the State of Utah and the Federal Government in accordance with an agreement between the Division of Water Rights, Utah Department of Natural Resources, and the Geological Survey. The investigation was financed during the period covered by this report by the following organizations: Utah Division of Water Rights (formerly State Engineer), Utah Division of Water Resources (formerly Water and Power Board), Salt Lake County, Salt Lake County Water Conservancy District, Central Utah Water Conservancy District, Metropolitan Water District of Salt Lake City, City of Murray, Granger-Hunter Improvement District, Taylorsville-Bennion Improvement District, Holladay Water Company, Magna Water and Sewer District, U.S. Bureau of Reclamation, U.S. Geological SurveyThe investigation encompasses the collection and interpretation of a large variety of climatologic, hydrologic, and geologic data in and near Salt Lake County. Utah Basic-Data Releases 11-13 and 15 contain data collected through 1967. This release contains climatologic and surface-water data for the 1968 water year (October 1967 to September 1968) and ground-water data collected during the 1968 calendar year. This is the final annual release of basic data for this investigation. Interpretive reports summarizing the results are in preparation. Organizations that furnished data are acknowledged in station descriptions and footnotes to tables.

  19. Development and Testing of the New Surface LER Climatology for OMI UV Aerosol Retrievals

    NASA Technical Reports Server (NTRS)

    Gupta, Pawan; Torres, Omar; Jethva, Hiren; Ahn, Changwoo

    2014-01-01

    Ozone Monitoring Instrument (OMI) onboard Aura satellite retrieved aerosols properties using UV part of solar spectrum. The OMI near UV aerosol algorithm (OMAERUV) is a global inversion scheme which retrieves aerosol properties both over ocean and land. The current version of the algorithm makes use of TOMS derived Lambertian Equivalent Reflectance (LER) climatology. A new monthly climatology of surface LER at 354 and 388 nm have been developed. This will replace TOMS LER (380 nm and 354nm) climatology in OMI near UV aerosol retrieval algorithm. The main objectives of this study is to produce high resolution (quarter degree) surface LER sets as compared to existing one degree TOMS surface LERs, to product instrument and wavelength consistent surface climatology. Nine years of OMI observations have been used to derive monthly climatology of surface LER. MODIS derived aerosol optical depth (AOD) have been used to make aerosol corrections on OMI wavelengths. MODIS derived BRDF adjusted reflectance product has been also used to capture seasonal changes in the surface characteristics. Finally spatial and temporal averaging techniques have been used to fill the gaps around the globes, especially in the regions with consistent cloud cover such as Amazon. After implementation of new surface data in the research version of algorithm, comparisons of AOD and single scattering albedo (SSA) have been performed over global AERONET sites for year 2007. Preliminary results shows improvements in AOD retrievals globally but more significance improvement were observed over desert and bright locations. We will present methodology of deriving surface data sets and will discuss the observed changes in retrieved aerosol properties with respect to reference AERONET measurements.

  20. Final Technical Report for "Radiative Heating Associated with Tropical Convective Cloud Systems: Its Importance at Meso and Global Scales"

    SciTech Connect

    Schumacher, Courtney

    2012-12-13

    Heating associated with tropical cloud systems drive the global circulation. The overall research objectives of this project were to i) further quantify and understand the importance of heating in tropical convective cloud systems with innovative observational techniques, and ii) use global models to determine the large-scale circulation response to variability in tropical heating profiles, including anvil and cirrus cloud radiative forcing. The innovative observational techniques used a diversity of radar systems to create a climatology of vertical velocities associated with the full tropical convective cloud spectrum along with a dissection of the of the total heating profile of tropical cloud systems into separate components (i.e., the latent, radiative, and eddy sensible heating). These properties were used to validate storm-scale and global climate models (GCMs) and were further used to force two different types of GCMs (one with and one without interactive physics). While radiative heating was shown to account for about 20% of the total heating and did not have a strong direct response on the global circulation, the indirect response was important via its impact on convection, esp. in how radiative heating impacts the tilt of heating associated with the Madden-Julian Oscillation (MJO), a phenomenon that accounts for most tropical intraseasonal variability. This work shows strong promise in determining the sensitivity of climate models and climate processes to heating variations associated with cloud systems.

  1. Effects of ice-crystal structure on halo formation: cirrus cloud experimental and ray-tracing modeling studies.

    PubMed

    Sassen, K; Knight, N C; Takano, Y; Heymsfield, A J

    1994-07-20

    During the 1986 Project FIRE (First International Satellite Cloud Climatology Project Regional Experiment) field campaign, four 22° halo-producing cirrus clouds were studied jointly from a groundbased polarization lidar and an instrumented aircraft. The lidar data show the vertical cloud structure and the relative position of the aircraft, which collected a total of 84 slides by impaction, preserving the ice crystals for later microscopic examination. Although many particles were too fragile to survive impaction intact, a large fraction of the identifiable crystals were columns and radial bullet rosettes, with both displaying internal cavitations, and radial plate-column combinations. Particles that were solid or displayed only a slight amount of internal structure were relatively rare, which shows that the usual model postulated by halo theorists, i.e., the randomly oriented, solid hexagonal crystal, is inappropriate for typical cirrus clouds. With the aid of new ray-tracing simulations for hexagonal hollow ended column and bullet-rosette models, we evaluate the effects of more realistic ice-crystal structures on halo formation and lidar depolarization and consider why the common halo is not more common in cirrus clouds.

  2. Effects of Ice-Crystal Structure on Halo Formation: Cirrus Cloud Experimental and Ray-Tracing Modeling Studies

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Knight, Nancy C.; Takano, Yoshihide; Heymsfield, Andrew J.

    1994-01-01

    During the 1986 Project FIRE (First International Satellite Cloud Climatology Project Regional Experiment) field campaign, four 22 deg halo-producing cirrus clouds were studied jointly from a ground-based polarization lidar and an instrumented aircraft. The lidar data show the vertical cloud structure and the relative position of the aircraft, which collected a total of 84 slides by impaction, preserving the ice crystals for later microscopic examination. Although many particles were too fragile to survive impaction intact, a large fraction of the identifiable crystals were columns and radial bullet rosettes, with both displaying internal cavitations and radial plate-column combinations. Particles that were solid or displayed only a slight amount of internal structure were relatively rare, which shows that the usual model postulated by halo theorists, i.e., the randomly oriented, solid hexagonal crystal, is inappropriate for typical cirrus clouds. With the aid of new ray-tracing simulations for hexagonal hollow-ended column and bullet-rosette models, we evaluate the effects of more realistic ice-crystal structures on halo formation and lidar depolarization and consider why the common halo is not more common in cirrus clouds.

  3. Cloud-Aerosol-Radiation (CAR) ensemble modeling system: Overall accuracy and efficiency

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Liang, Xin-Zhong; Zeng, Qingcun; Gu, Yu; Su, Shenjian

    2013-07-01

    The Cloud-Aerosol-Radiation (CAR) ensemble modeling system has recently been built to better understand cloud/aerosol/radiation processes and determine the uncertainties caused by different treatments of cloud/aerosol/radiation in climate models. The CAR system comprises a large scheme collection of cloud, aerosol, and radiation processes available in the literature, including those commonly used by the world's leading GCMs. In this study, detailed analyses of the overall accuracy and efficiency of the CAR system were performed. Despite the different observations used, the overall accuracies of the CAR ensemble means were found to be very good for both shortwave (SW) and longwave (LW) radiation calculations. Taking the percentage errors for July 2004 compared to ISCCP (International Satellite Cloud Climatology Project) data over (60°N, 60°S) as an example, even among the 448 CAR members selected here, those errors of the CAR ensemble means were only about -0.67% (-0.6 W m-2) and -0.82% (-2.0 W m-2) for SW and LW upward fluxes at the top of atmosphere, and 0.06% (0.1 W m-2) and -2.12% (-7.8 W m-2) for SW and LW downward fluxes at the surface, respectively. Furthermore, model SW frequency distributions in July 2004 covered the observational ranges entirely, with ensemble means located in the middle of the ranges. Moreover, it was found that the accuracy of radiative transfer calculations can be significantly enhanced by using certain combinations of cloud schemes for the cloud cover fraction, particle effective size, water path, and optical properties, along with better explicit treatments for unresolved cloud structures.

  4. An automated satellite cloud classification scheme using self-organizing maps: Alternative ISCCP weather states

    NASA Astrophysics Data System (ADS)

    McDonald, Adrian J.; Cassano, John J.; Jolly, Ben; Parsons, Simon; Schuddeboom, Alex

    2016-11-01

    This study explores the application of the self-organizing map (SOM) methodology to cloud classification. In particular, the SOM is applied to the joint frequency distribution of the cloud top pressure and optical depth from the International Satellite Cloud Climatology Project (ISCCP) D1 data set. We demonstrate that this scheme produces clusters which have geographical and seasonal patterns similar to those produced in previous studies using the k-means clustering technique but potentially provides complementary information. For example, this study identifies a wider range of clusters representative of low cloud cover states with distinct geographic patterns. We also demonstrate that two rather similar clusters, which might be considered the same cloud regime in other classifications, are distinct based on the seasonal variation of their geographic distributions and their cloud radiative effect in the shortwave. Examination of the transitions between regimes at particular geographic positions between one day and the next also shows that the SOM produces an objective organization of the various cloud regimes that can aid in their interpretation. This is also supported by examination of the SOM's Sammon map and correlations between neighboring nodes geographic distributions. Ancillary ERA-Interim reanalysis output also allows us to demonstrate that the clusters, identified based on the joint histograms, are related to an ordered continuum of vertical velocity profiles and two-dimensional vertical velocity versus lower tropospheric stability histograms which have a clear structure within the SOM. The different nodes can also be separated by their longwave and shortwave cloud radiative effect at the top of the atmosphere.

  5. Cloud Interactions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 1 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

    Image information: VIS instrument. Latitude 68.4, Longitude 258.8 East (101.2 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration

  6. A Study of the Role of Clouds in the Relationship Between Land Use/Land Cover and the Climate and Air Quality of the Atlanta Area

    NASA Technical Reports Server (NTRS)

    Kidder, Stanley Q.; Hafner, Jan

    1997-01-01

    The goal of Project ATLANTA is to derive a better scientific understanding of how land cover changes associated with urbanization affect local and regional climate and air quality. Clouds play a significant role in this relationship. Using GOES images, we found that in a 63-day period (5 July-5 September 1996) there were zero days which were clear for the entire daylight period. Days which are cloud-free in the morning become partly cloudy with small cumulus clouds in the afternoon in response to solar heating. This result casts doubt on the applicability of California-style air quality models which run in perpetual clear skies. Days which are clear in the morning have higher ozone than those which are cloudy in the morning. Using the RAMS model, we found that urbanization increases the skin surface temperature by about 1.0-1.5 C on average under cloudy conditions, with an extreme of +3.5 C. Clouds cool the surface due to their shading effect by 1.5-2.0 C on average, with an extreme of 5.0 C. RAMS simulates well the building stage of the cumulus cloud field, but does poorly in the decaying phase. Next year's work: doing a detailed cloud climatology and developing improved RAMS cloud simulations.

  7. A new evaporation duct climatology over the South China Sea

    NASA Astrophysics Data System (ADS)

    Shi, Yang; Yang, Kunde; Yang, Yixin; Ma, Yuanliang

    2015-10-01

    The climatology of evaporation ducts is important for shipborne electromagnetic system design and application. The evaporation duct climatology that is currently used for such applications was developed in the mid 1980s; this study presents efforts to improve it over the South China Sea (SCS) by using a state-of-the-art evaporation duct model and an improved meteorology dataset. This new climatology provides better evaporation duct height (EDH) data over the SCS, at a higher resolution of 0.312°×0.313°. A comparison between the new climatology and the old one is performed. The monthly average EDH in the new climatology is between 10 and 12 m over the SCS, higher than that in the old climatology. The spatiotemporal characteristics of the evaporation duct over the SCS in different months are analyzed in detail, based on the new climatology.

  8. Crater Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA06085 Crater Clouds

    The crater on the right side of this image is affecting the local wind regime. Note the bright line of clouds streaming off the north rim of the crater.

    Image information: VIS instrument. Latitude -78.8N, Longitude 320.0E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spac