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NASA NTRS2006

The Development Of Enabling Technologies For Submillimeter-Wave Remote Sensing of Ice Clouds From Space

This paper presents the chronological development of technologies and techniques that have led to a satellite mission concept aimed at quantifying the temporal and spatial distributions of upper tropospheric ice clouds. The Submillimeter-wave and Infrared Ice Cloud Experiment (SIRICE) is an Earth System Science Pathfinder mission concept designed to improve our understanding of the upper tropospheric water cycle and its coupling to the Earth s radiation budget. Ice outflow from convective storm systems is known to play an important role in regional energy budgets; however, ice generation and subsequent precipitation and sublimation are poorly quantified. SIRICE will provide measurements of ice cloud distributions and microphysical properties which are needed for understanding the crucial link between the hydrologic and energy cycles. The SIRICE measurement platform is comprised of two integrated instruments, the Submillimeter/millimeter-wave radiometer (SM4) and the Infrared Cloud Ice Radiometer (IRCIR). The primary instrument is the SM4, a conical scanner that provides a 1600 km swath of the Earth's surface at 53 degree incidence. The SM4 has 6 linearly polarized receivers measuring 12 spectral bands centered at 183 GHz, 325 GHz, 448 GHz, 643 GHz and 874 GHz; two receivers at 643 GHz measure horizontal and vertical polarizations. Submillimeter-wavelengths are well suited to the remote sensing of ice clouds due to the relative size of the wavelengths to particle sizes. Upwelling emission from lower tropospheric water vapor is scattered by the ice clouds thus causing a brightness temperature depression at submillimeter wavelengths. The IRCIR is a push broom imager with approximately 1500 km swath and spectral channels at 11 and 12 micrometers. This combination of coincident infrared and submillimeter-wavelength measurements were chosen because of its ability to provide retrieval of ice water path and median particle size for a wide range of ice clouds from thin cirrus to thick anvil structures. Over the past decade there has been a parallel development of submillimeter-wave technologies, demonstration instruments, and remote sensing techniques that have led to the present SIRICE mission concept. Mapping of these developmental paths reveals the origins, rational and maturity of features of the SIRICE payload such as its channel selection, compact design, and multipoint calibration. This presentation traces the evolution of the SIRICE mission concept from the early 1990's to its present status.

Racette, Paul↗
NASA NTRS1995

Airborne spectrograph for the thermal IR: Broadband Array Spectrograph System

Spectroscopic studies in the 'fingerprint' region of the thermal IR from 3 to 14 microns of celestial dust components and the overall energy distribution of the sources are best served by moderate spectral resolution (R = lambda/Delta lambda approximately 30 to 200), high sensitivity observations. Spectral purity and the reproducibility of the spectral shape are critical as well, when using the spectral shape to assign temperatures to dust grains or to gas clouds based on the wavelength and shape of molecular bands. These sensor attributes are also important to the use of wavelengths and ratios of solid state features to derive compositions of dust grains in celestial sources. The advent of high quality linear arrays of blocked impurity band (BIB) detectors of Si:As permitted the development of a state-of-the-art, patented, cooled prism spectrograph. Developed at The Aerospace Corporation largely with in-house funds, the Broadband Array Spectrograph System (BASS) has been used for a variety of remote sensing applications, but especially for IR astronomical studies on the Kuiper Airborne Observatory and at the NASA Infrared Telescope Facility (IRTF). The attributes of the spectrograph, specifically having the pupil imaged onto the 2 linear 58 element detector arrays so that the effects of guiding errors are minimized, being able to maximally exploit the limited observing time by acquiring all 116 spectral channels simultaneously, and having all spectral channels imaged through the same aperture so that spectral mapping is readily and reliably accomplished, afford the scientist with a unique opportunity to conduct both surveys of examples of many different types of sources as well as in-depth studies of a given class of object by thoroughly sampling the class members. This duality was demonstrated with the BASS through a combination of KAO flights where spectral maps were obtained as part of in-depth studies of specific source regions (such as Orion and W3) and flights where up to 21 legs/flight were used to survey many different sources of different types.

Russell, Ray W.↗
NASA NTRS2000

Sensing Water Vapon via Spacecraft Radio Occultation Observations

The radio occultation technique has been used to characterize planetary atmospheres since the 1960's spanning atmospheric pressures from 16 microbars to several bars. In 1988, the use of GPS signals to make occultation observations of Earth's atmosphere was realized by Tom Yunck and Gunnar Lindal at JPL. In the GPS to low-Earth-orbiter limb- viewing occultation geometry, Fresnel diffraction yield a unique combination of high vertical resolution of 100 m to 1 km at long wavelengths (approx. 20 cm) insensitive to particulate scattering which allows routine limb sounding from the lower mesosphere through the troposphere. A single orbiting GPS/GLONASS receiver can observe - 1000 to 1400 daily occultations providing as many daily, high vertical resolution soundings as the present global radiosonde network, but with far more evenly distributed, global coverage. The occultations yield profiles of refractivity as a function of height. In the cold, dry conditions of the upper troposphere and above (T less than 240 K), profiles of density, pressure (geopotential), and temperature can be derived. Given additional temperature information, water vapor can be derived in the midddle and lower troposphere with a unique combination of vertical resolution, global distribution and insensitivity to clouds and precipitation to an accuracy of approx. 0.2 g/kg. At low latitudes, moisture profiles will be accurate to 1-5% within the convective boundary layer and better than 20% below 6 to 7 km. Accuracies of climatological averages should be approx. 0. 1 g/kg limited by the biases in the temperature estimates. To use refractivity to constrain water vapor, knowledge of temperature is required. The simplest approach is to use the temperature field from an analysis such as the 6 hour ECMWF global analysis interpolated to the locations of each occultation. A better approach is to combine the temperature and moisture fields from such an analysis with the occultation refractivity in a weighting scheme based on the errors in each data field. A ID variational combinational approach has been developed at the UKMO. We win present results from both approaches from GPS/MET data taken in June and July 1995 and compare them with the ECMWF global 6 hour moisture analyses which are derived largely from TOVS and radiosonde data. Overall, the atmosphere below the 500 mb level appears somewhat drier in general than the ECNIWF humidity field. A 2-D (latitude vs. height) climatological snapshot derived from a 2-week span of GPS/MET data will be compared to the humidity climatology of Peixoto and Oort derived from radiosonde data from 1963-1973. Differences between the GPS results and Peixoto and Oort may be the signature of a climate trend over the past 30 years.

Kursinski, E. Robert↗
NASA NTRS1993

Extraction of auxiliary data from AVIRIS distribution tape for spectral, radiometric, and geometric quality assessment

Remotely sensed data are affected by system (sensor and platform), and scene related effects. For quantitative investigations the spectral, radiometric characteristics of the system and scene have to be known. The relevant effects and their possible influence on an image have to be specifically determined for every remote sensing system and adequate description parameters need to be updated and reported on a regular basis as they are carried out, e.g., for the AVIRIS system. It is evident that the strength of the influence of similar effects in very dependent on the accessibility of auxiliary information about such sensor systems. Degradation in a spaceborne system can normally be just reported and cannot be corrected. In contrast, an airborne sensor can be evaluated, maintained and improved periodically. Such maintenance efforts are particularly important because airborne systems are exposed to extreme and changing environments. These include tens of takeoffs and landing each year as well as extreme changes in temperature and humidity on the tarmac and in flight. For the AVIRIS system there are environmental stresses such as changes in temperature, air pressure, humidity, vibration of the platform or scene-related reasons like atmospheric conditions, and topography. The information contained in the auxiliary files included with the AVIRIS data can be used to assess these effects and compensate for them. In addition the spectral, radiometer and geometric calibration data contained in the auxiliary file are required for quantitative analysis of the data. The paper describes tools to access the auxiliary information that characterizes the AVIRIS system. These tools allow the examination of parameters that may impact the quality of the measured AVIRIS image. An example of the use of this auxiliary data was carried out with regard to a parametric geocoding approach. Emphasis is placed on the reported auxiliary information that describes the geometric character of the AVIRIS data in 1991. Results are presented using data from the AVIRIS flight #910705, run 6 and 7 of the NASA MAC Europe 1991 campaign in a test site in Central Switzerland.

Meyer, Peter↗
NASA NTRSDate not supplied

TPSAS-NF1676L-11308-DND

The Lidar Atmospheric Sensing Experiment (LASE) system has operated on the NASA ER-2, P-3, and DC-8 aircraft during the past 16 years and participated in 13 field experiments. This system provides vertical profiles of water vapor mixing ratio and aerosol and cloud backscattering. A brief overview is presented on the upgrade of LASE that included refurbishment of laser diode seeding, control and data system, and zenith receiver system. These developments have enhanced the operational reliability of the system and improved its performance. The LASE system was deployed on the NASA DC-8 aircraft recently for the NASA GRIP (Genesis and Rapid Intensification Processes) field experiment, which was conducted during August and September 2010 from operational bases in Fort Lauderdale, FL and St. Croix, VI. Initial measurements from this field experiment are presented including distributions of water vapor, aerosol, and clouds. Temperature profiles from DC-8 dropsondes and nearby radiosondes are used to derive relative humidity profiles from the LASE water vapor mixing ratio profiles. Comparisons of LASE water vapor mixing ratio profiles with those measured by the new AVAPS-II dropsondes from the NASA DC-8 are also presented.

Susan A Kooi↗
NASA NTRS1991

Aerosol sensing from balloons using photopolarimetry

A photopolarimeter designed to measure the radiance and the polarization ratio at lambda equals 0.85 microns and lambda equals 1.65 microns is set up on a gondola of a stratospheric balloon. By rotating the gondola, measurements of the diffuse solar light are obtained for a wide range of the scattering angles. An inversion scheme, based on the assumption of a log-normal size distribution, provides the relevant size parameters, the refractive index, and the slant optical thicknesses of the aerosols. Since 1983, this experiment was launched twice a year from Aire Sur Adour (S-E of France). The post-El Chichon atmospheric stratospheric aerosol proved to be quite stable in size and nature (hydratid sulfuric acid), but the abundance decreased by a factor of 10 between 1983 and 1987. The experiment was also launched to observe the stratosphere during the Arctic winter. Two flights, on January 28, 1988 and January 18, 1990, corresponded to an unperturbed atmosphere. But during a third flight, on April, 2, 1990, the temperatures were low enough for PCS formulations. A multilayer situation was observed with the standard H2SOH aerosols below 20 km; a dense layer was observed, peaked at around 23 km, with scattering coefficients about 50 times layer than in background conditions; and an upper layer was observed, rather sharp (approximately equal to 1 km), with micron sized particles.

Santer, R.↗
NASA NTRS1998

Assessment of Anthropogenic and Climatic Impacts on the Global Carbon Cycle Using a 3-D Model Constrained by Isotopic Carbon Measurements and Remote Sensing of Vegetation

Our original proposal called for improved modeling of the terrestrial biospheric carbon cycle, specifically using biome-specific process models to account for both the energy and water budgets of plant growth, to facilitate investigations into recent changes in global atmospheric CO2 abundance and regional distribution. The carbon fluxes predicted by these models were to be incorporated into a global model of CO2 transport to establish large-scale regional fluxes of CO2 to and from the terrestrial biosphere subject to constraints imposed by direct measurements of atmospheric CO2 and its 13C/12C isotopic ratio. Our work was coordinated with a NASA project (NASA NAGW-3151) at the University of Montana under the direction of Steven Running, and was partially funded by the Electric Power Research Institute. The primary objective of this project was to develop and test the Biome-BGC model, a global biological process model with a daily time step which simulates the water, energy and carbon budgets of plant growth. The primary product, the unique global gridded daily land temperature, and the precipitation data set which was used to drive the process model is described. The Biome-BGC model was tested by comparison with a simpler biological model driven by satellite-derived (NDVI) Normalized Difference Vegetation Index and (PAR) Photosynthetically Active Radiation data and by comparison with atmospheric CO2 observations. The simple NDVI model is also described. To facilitate the comparison with atmospheric CO2 observations, a three-dimensional atmospheric transport model was used to produce predictions of atmospheric CO2 variations given CO2 fluxes owing to (NPP) Net Primary Productivity and heterotrophic respiration that were produced by the Biome-BGC model and by the NDVI model. The transport model that we used in this project, and errors associated with transport simulations, were characterized by a comparison of 12 transport models.

Keeling, Charles D.↗
NASA NTRS1982

Sources of atmospheric methane from coastal marine wetlands

Biological methanogenesis in wetlands is believed to be one of the major sources of global tropospheric methane. The present paper reports measurements of methane distribution in the soils, sediments, water and vegetation of coastal marine wetlands. Measurements, carried out in the salt marshes Bay Tree Creek in Virginia and Panacea in northwest Florida, reveal methane concentrations in soils and sediments to vary with depth below the surface and with soil temperature. The fluxes of methane from marsh soils to the atmosphere at the soil-air interface are estimated to range from -0.00067 g CH4/sq m per day (methane sink) to 0.024 g CH4/sq m per day, with an average value of 0.0066 g CH4/sq m per day. Data also demonstrate the important role of tidal waters percolating through marsh soils in removing methane from the soils and releasing it to the atmosphere. The information obtained, together with previous studies, provides a framework for the design of a program based on in situ and remote sensing measurements to study the global methane cycle.

Harriss, R. C.↗
NASA NTRS2000

BOREAS AFM-03-NCAR Electra 1994 Aircraft Sounding Data

The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-3 team used the National Center for Atmospheric Research's (NCAR) Electra aircraft to make sounding measurements to study the planetary boundary layer using in situ and remote-sensing measurements. Measurements were made of wind speed and direction, air pressure and temperature, potential temperature, dewpoint, mixing ratio of H, O, CO, concentration, and ozone concentration. Twenty-five research missions were flown over the Northern Study Area (NSA), Southern Study Area (SSA), and the transect during BOREAS Intensive Field Campaigns (IFCs) 1, 2, and 3 during 1994. All missions had from four to ten soundings through the top of the planetary boundary layer. This sounding data set contains all of the in situ vertical profiles through the boundary layer top that were made (with the exception of 'porpoise' maneuvers). Data were recorded in one-second time intervals. These data are stored in tabular ASCII files. The NCAR Electra 1994 aircraft sounding data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Lenschow, Donald H.↗
NASA NTRS2009

Cold Season QPF: Sensitivities to Snow Parameterizations and Comparisons to NASA CloudSat Observations

As operational numerical weather prediction is performed at increasingly finer spatial resolution, precipitation traditionally represented by sub-grid scale parameterization schemes is now being calculated explicitly through the use of single- or multi-moment, bulk water microphysics schemes. As computational resources grow, the real-time application of these schemes is becoming available to a broader audience, ranging from national meteorological centers to their component forecast offices. A need for improved quantitative precipitation forecasts has been highlighted by the United States Weather Research Program, which advised that gains in forecasting skill will draw upon improved simulations of clouds and cloud microphysical processes. Investments in space-borne remote sensing have produced the NASA A-Train of polar orbiting satellites, specially equipped to observe and catalog cloud properties. The NASA CloudSat instrument, a recent addition to the A-Train and the first 94 GHz radar system operated in space, provides a unique opportunity to compare observed cloud profiles to their modeled counterparts. Comparisons are available through the use of a radiative transfer model (QuickBeam), which simulates 94 GHz radar returns based on the microphysics of cloudy model profiles and the prescribed characteristics of their constituent hydrometeor classes. CloudSat observations of snowfall are presented for a case in the central United States, with comparisons made to precipitating clouds as simulated by the Weather Research and Forecasting Model and the Goddard single-moment microphysics scheme. An additional forecast cycle is performed with a temperature-based parameterization of the snow distribution slope parameter, with comparisons to CloudSat observations provided through the QuickBeam simulator.

Molthan, A. L.↗
NASA NTRSDate not supplied

Pneumatic Sampler (P-Sampler) for the Martian Moons Exploration (MMX)

The Martian Moons eXploration (MMX) mission, led by the Japanese Aerospace Exploration Agency (JAXA), will focus on the exploration of the two Martian moons – Phobos and Deimos (Figure 1). The spacecraft will perform close-up remote sensing and observations of both moons and collect a sample from Phobos for Earth sample return. MMX has set the two mission goals: (1) determining the origin of the Martian moons and (2) observing processes in the circumplanetary environment of Mars, based on remote sensing, in-situ observations, and laboratory analyses of returned samples of Phobos regolith [1-2]. To fulfill the mission goals, MMX employs a double sampling approach: Coring and Pneumatic Samplers (Figure 2).The Coring Sampler (C-Sampler), a core soil tube deployed by a robotic arm, providing access to the building blocks of Phobos beneath the surface (>2 cm), and also collect a mixture of near surface material. The P-Sampler, on the other hand, would selectively sample the surface veneer and provides reference of surface component with the C-Sampler. The double sampling system not only enhances the scientific merits of MMX but also reduces risks associated with the sampling of Phobos. Without enough knowledge of the physical and chemical properties, and the geotechnical conditions of the surface of Phobos (e.g., compositions, temperature gradient/variation, porosity, grain size distribution), having two sampling systems that utilize entirely different sampling approaches is prudent.

Dylan Van Dyne↗
NASA NTRS2024

Baltimore Energy & Infrastructure: Assessing Urban Heat Vulnerability in Baltimore Neighborhoods to Inform Transportation Resiliency Planning Efforts

Across the world, climate change is altering cities and their local climate systems. Following global trends of rising mean temperatures, Baltimore, Maryland is projected to experience more frequent extreme heat events. Exacerbated by Urban Heat Island (UHI) effects, residents of the city face high temperatures from limited tree canopy, highly paved and impervious surfaces, limited air flow, and high concentrations of localized emissions. Urban heat is dispersed asymmetrically, with historically marginalized populations experiencing disproportionately severe heat. Recognizing the impacts of extreme urban heat, the Maryland Transit Administration (MTA) collaborated with us, the Spring 2024 Goddard Energy and Infrastructure NASA DEVELOP team to assess urban impacts of MTA users and assets and explore opportunities to enhance resiliency planning. We evaluated the feasibility of NASA Earth observations (EOs) in visualizing heat vulnerability in Baltimore City and County. We mapped UHI and extreme heat using remote sensing observations, tailored a Heat Priority Score (HPS) to analyze heat data in tandem with socioeconomic data from American Community Survey (ACS), and utilized SOlar and LongWave Environmental Irradiance Geometry (SOLWEIG) model to estimate MTA riders’ thermal comfort. NASA EOs served to quantify the distribution and severity of extreme heat at the block group level, which was found to correlate with a lack of vegetation and presence of densely built-up surroundings. The HPS revealed that extreme heat events most negatively impact communities that exhibit social vulnerability through indicators such as age, race, and income. These findings will inform neighborhood resiliency plans for the MTA that can be incorporated into their Adaptation Resiliency Toolbox (ART).

Baltimore,↗
NASA NTRS1991

Aspects of the evolution of the marine boundary layer during cold-air outbreaks off the southeast coast of the United States

Remote sensing and in situ measurements that were obtained in February 1986 were combined with the results from a boundary-layer model to study aspects of the evolution of the maine boundary layer (MBL) during two cold-air outbreaks (CAO) off the southeast coast of the United States. Maximum total heat fluxes occurred over the Gulf Stream northeast of Cape Hatteras where very cold, dry air encountered the Gulf Stream and where the wind speeds were very large. Maximum 6-h values for the total heat flux were as high as 2015 W/m. The magnitude of the area-average heat flux in the MBL was influenced not only by the surface air and dewpoint temperatures and the surface wind speeds off the coast but also by the area covered by Gulf Stream water (sea surface temperature greater than 22 C). The heat flux distribution off the coast rapidly produced large horizontal temperature and humidity differences over distances on the order of 100 km.

Vukovich, Fred M.↗
NASA NTRS1990

Physical retrieval of precipitation water contents from Special Sensor Microwave/Imager (SSM/I) data. Part 1: A cloud ensemble/radiative parameterization for sensor response (report version)

The physical retrieval of geophysical parameters based upon remotely sensed data requires a sensor response model which relates the upwelling radiances that the sensor observes to the parameters to be retrieved. In the retrieval of precipitation water contents from satellite passive microwave observations, the sensor response model has two basic components. First, a description of the radiative transfer of microwaves through a precipitating atmosphere must be considered, because it is necessary to establish the physical relationship between precipitation water content and upwelling microwave brightness temperature. Also the spatial response of the satellite microwave sensor (or antenna pattern) must be included in the description of sensor response, since precipitation and the associated brightness temperature field can vary over a typical microwave sensor resolution footprint. A 'population' of convective cells, as well as stratiform clouds, are simulated using a computationally-efficient multi-cylinder cloud model. Ensembles of clouds selected at random from the population, distributed over a 25 km x 25 km model domain, serve as the basis for radiative transfer calculations of upwelling brightness temperatures at the SSM/I frequencies. Sensor spatial response is treated explicitly by convolving the upwelling brightness temperature by the domain-integrated SSM/I antenna patterns. The sensor response model is utilized in precipitation water content retrievals.

Olson, William S.↗
NASA NTRS1998

Atmospheric and Spectroscopic Research in the Far Infrared

The spectroscopic measurements of molecular parameters constitute one of the major areas of our research program. This part of our program has been conducted in close collaboration with Smithsonian Astrophysical Observatory (SAO) and National Institute of Standards and Technology (NIST). The references on HO2, OH, and O2 that appear on the publication list are examples of this type of work completed during the grant period. These pressure-broadening studies have provided the kind of improvements needed in the database for retrieving atmospheric profiles from far infrared limb sensing data. Authors summarized the laboratory spectroscopic studies conducted during the grant period. We attempted to measure the pressure broadening coefficients of the O2 lines in the 50 and 117/ cm regions. An accurate characterization of these lines using the IBEX detector system was needed to analyze the flight data. These are difficult lines to measure because they arise from weak magnetic dipole transitions. We used a 4-meter absorption cell to obtain the pressure broadening coefficients for the 50 and 83 /cm lines. We also completed the pressure broadening studies including the temperature dependence of two lines of OH at 83 and 118 /cm. These two lines are important not only for the balloon data retrieval work but also for the future project proposals.Another area of focus in our program is the far infrared detector research. The third area of focus deals with data distribution and dissemination.

Park, Kwangjai↗
NASA NTRS1997

Microwave Remote Sensing of Soil Moisture for Estimation of Soil Properties

Surface soil moisture dynamics was derived using microwave remote sensing, and employed to estimate soil physical and hydraulic properties. The L-band ESTAR radiometer was employed in an airborne campaign over the Little Washita watershed, Oklahoma during June 10-18, 1992. Brightness temperature (TB) data were employed in a soil moisture inversion algorithm which corrected for vegetation and soil effects. Analyses of spatial TB and soil moisture dynamics during the dry-down period revealed a direct relationship between changes in TB, soil moisture and soil texture. Extensive regression analyses were carried out which yielded statistically significant quantitative relationships between ratio of percent sand to percent clay (RSC, a term derived to quantify soil texture) and saturated hydraulic conductivity (Ksat) in terms of change components of TB and surface soil moisture. Validation of results indicated that both RSC and Ksat can be estimated with reasonable accuracy. These findings have potential applications for deriving spatial distributions of RSC and Ksat over large areas.

Mattikalli, Nandish M.↗
NASA NTRS2008

Titan's Atmospheric Dynamics and Meteorology

Titan, after Venus, is the second example of an atmosphere with a global cyclostrophic circulation in the solar system, but a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10degS, indicate that the zonal winds are generally in the sense of the satellites rotation. They become cyclostrophic approx. 35 km above the surface and generally increase with altitude, with the exception of a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from the temperature field retrieved from Cassini measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds at mid northern latitudes of 190 ms-' near 300 km. Above this level, the vortex decays. Curiously, the zonal winds and temperatures are symmetric about a pole that is offset from the surface pole by approx.4 degrees. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the offset between the equator, where the distance to the rotation axis is greatest, and the solar equator. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures in the north polar region near 400 km and the enhanced concentration of several organic molecules suggests subsidence there during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50degN. Titan's winter polar vortex appears to share many of the same characteristics of winter vortices on Earth-the ozone holes. Global mapping of temperatures, winds, and composition in he troposphere, by contrast, is incomplete. The few suitable discrete clouds that have bee found for tracking indicate smaller velocities than aloft, consistent with the Huygens measurements. At low latitudes the zonal winds near the surface appear not to be westward as on Earth, but eastward. Because the net zonal-mean time-averaged torq exerted by the surface on the atmosphere should vanish, this implies westward flow o part of the surface; the question is where. The latitude contrast in tropospheric temperatures, deduced from radio occultations at low, mid, and high latitudes, is small approx.5 K at the tropopause and approx.3 K at the surface.

Flasar, F. M.↗
NASA NTRS2011

Tracking Climate Effects on Plant-Pollinator Interaction Phenology with Satellites and Honey Bee Hives

Background/Question/Methods: The complexity of plant-pollinator interactions, the large number of species involved, and the lack of species response functions present challenges to understanding how these critical interactions may be impacted by climate and land cover change on large scales. Given the importance of this interaction for terrestrial ecosystems, it is desirable to develop new approaches. We monitor the daily weight change of honey bee (Apis mellifera) colonies to record the phenology of the Honey Bee Nectar Flow (HBNF) in a volunteer network (honeybeenet.gsfc.nasa.gov). The records document the successful interaction of a generalist pollinator with a variety of plant resources. We extract useful HBNF phenology metrics for three seasons. Sites currently exist in 35 states/provinces in North America, with a concentration in the Mid-Atlantic region. HBNF metrics are compared to standard phenology metrics derived from remotely sensed vegetation indices from NASA's MODIS sensor and published results from NOAA's A VHRR. At any given time the percentage of plants producing nectar is usually a sma11 fraction of the total satellite sensor signal. We are interested in determining how well the 'bulk' satellite vegetation parameters relate to the phenology of the HBNF, and how it varies spatially on landscape to continental scales. Results/Conclusions: We found the median and peak seasonal HBNF dates to be robust, with variation between replicate scale hives of only a few days. We developed quality assessment protocols to identify abnormal colony artifacts. Temporally, the peak and median of the HBNF in the Mid-Atlantic show a significant advance of 0.58 d/y beginning about 1970, very similar to that observed by the A VHRR since 1982 (0.57 d/y). Spatially, the HBNF metrics are highly correlated with elevation and winter minimum temperature distribution, and exhibit significant but regionally coherent inter-annual variation. The relationship between median of the spring HBNF with the "Green-up" metric from the 500 meter MODIS NDVI phenology product, for sites throughout the Eastern US 2000-2009, is well described by a single linear fit (r(exp 2) = 0.72). We conclude.that for the tree-dominated areas of the Eastern US at least the spring HBNF can be tracked very well by MODIS phenology. Analysis of other regions and seasons is presently underway but with more limited data. Spatial patterns in the eastern US and management implications will be presented and discussed.

Esaias, Wayne E.↗