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At least 181 records · Page 10

Lessons Learned from Flight Observations of the GOES-R Magnetometer

The Geostationary Operational Environmental Satellite (GOES)-16 observatory was launched on 19 November 2016. During daily on-orbit operations, shadowing of the inboard magnetometer sensor unit occurs due to spacecraft geometry and solar angle. Throughout the shadowing periods of the inboard magnetometer, anomalous excursions of 20 nanotesla (nT) are observed. In addition to the excursions during shadow events, the measurement difference between the inboard and outboard magnetometer varies over the day, indicating erroneous measurements by one or both magnetometers. In addition, based on the deployment rotations, the zero offsets of the X and Y axes were found to be significantly different, ~30nT, from ground calibration data. Because of these observations, an extensive root cause investigation was undertaken to correct the magnetometer system for the next spacecraft in the GOES-R series. This paper documents the efforts of that activity and the lessons learned as a result of the investigation.

GOES-R↗

Extended Coronal Imaging with GOES-R Solar UltraViolet Imager

Solar corona in 17.1nm and 19.5nm wavelengths up to three solar radii from Sun center was observed by the Solar UltraViolet Imager (SUVI) on the Geostationary Operational Environmental Satellite (GOES) – 16 and GOES‐17. The nominally Sun‐pointed SUVI was off‐pointed to the left and to the right of the Sun center at a regular cadence and a composite Extended Coronal Imaging (ECI) frame was created. The imaging area in the composite is about three times the nominal image area in the East‐West direction (about 5*R(sub Sun) versus 1.6*R(sub Sun) for nominal images). The campaign was conducted in February (4 hours), June (72 hours), and August‐September of 2018 (5 weeks). Limited solar CME activity during the 5‐week campaign was observed in both the SUVI and LASCO C2 imagers. Some of the observations during this campaign include structures up to a few solar radii off the solar limb, and interesting coronal activity – both on and off the solar disk. They are presented here.

EUV Solar Corona↗

Spatial Downscaling of GOES-R Land Surface Temperature over Urban Regions: A Case Study for New York City

The surface urban heat island (SUHI) effect is among the major environmental issues encountered in urban regions. To better predict the dynamics of the SUHI and its impacts on extreme heat events, an accurate characterization of the surface energy balance in urban regions is needed. However, the ability to improve understanding of the surface energy balance is limited by the heterogeneity of surfaces in urban areas. This study aims to enhance the understanding of the urban surface energy budget through an innovation in the use of land surface temperature (LST) observations from remote sensing satellites. A LST database with 5–min temporal and 30–m spatial resolution is developed by spatial downscaling of the Geostationary Operational Environmental Satellites—R (GOES–R) series LST product over New York City (NYC). The new downscaling method, known as the Spatial Downscaling Method (SDM), benefits from the fine spatial resolution of Landsat–8 and high temporal resolution of GOES–R, and considers the temporal variation in LST for each land cover type separately. Preliminary results show that the SDM can reproduce the temporal and spatial variability of LST over NYC reasonably well and the downscaled LST has a spatial root mean square error (RMSE) of the order of 2 K as compared to the independent Landsat–8 observations. The SDM shows smaller RMSE of 1.93 K over the tree canopy land cover, whereas RMSE is 2.19 K for built–up areas. The overall results indicate that the SDM has potential to estimate LST at finer spatial and temporal scales over urban regions.

land surface temperature↗

Cross-Calibration of the GPS Constellation CXD Proton Data with GOES EPS

Accurate proton flux measurements of the near Earth environment are essential to the understanding of many phenomena which have a direct impact on our lives. Currently there is only a small set of satellites capable of performing these measurements which makes certain studies and analyses difficult. This paper details the capabilities of the Combined X-ray Dosimeter (CXD), flown on 21 satellites of the Global Positioning System (GPS) constellation, as it relates to proton measurements. We present a cross-calibration of the CXD with the Energetic Particle Sensor (EPS) onboard the Geostationary Operational Environmental Satellite (GOES) operated by the National Oceanic and Atmospheric Administration (NOAA). By utilizing Solar Energetic Particle Events (SEPEs) when both sets of satellites were operational we have orders of magnitude in flux and energy to compare against. Robust statistical analyses show that the CXD and GOES flux calculations are similar and that for proton energies > 30 MeV the CXD fluxes are on average within 20% of EPS. Although the CXD has a response to protons as low as 6 MeV the sensitivity at energies below 20 MeV is reduced and so flux comparisons of these are generally worse. Integral flux values > 10 MeV are typically within 40% of EPS. These calibrated CXD data sets will give researchers capabilities to study solar proton access to the inner magnetosphere down to L ~ 4 near the equatorial plane at high temporal cadence.

79 ASTRONOMY AND ASTROPHYSICS↗

Reexamination of 2.5-Ga “whiff” of oxygen interval points to anoxic ocean before GOE

Transient appearances of oxygen have been inferred before the Great Oxygenation Event (GOE) [~2.3 billion years (Ga) ago] based on redox-sensitive elements such as Mo and S—most prominently from the ~2.5-Ga Mount McRae Shale in Western Australia. We present new spatially resolved data including synchrotron-based x-ray spectroscopy and secondary ion mass spectrometry to characterize the petrogenesis of the Mount McRae Shale. Sediments were primarily composed of organic matter and volcanic ash (a potential source of Mo), with U-Pb ages revealing extremely low sedimentation rates. Catagenesis created bedding-parallel microfractures, which subsequently acted as fluid pathways for metasomatic alteration and recent oxidative weathering. Our collective observations suggest that the bulk chemical datasets pointing toward a “whiff” of oxygen developed during postdepositional events. Nonzero Δ 33 S in trace-metal–poor, early diagenetic pyrite and the unusually enriched organic carbon at low sedimentation rates instead suggest that environmental oxygen levels were negligible ~150 million years before the GOE.

59 BASIC BIOLOGICAL SCIENCES↗

Improving Satellite Quantitative Precipitation Estimation Using GOES-Retrieved Cloud Optical Depth

To address significant gaps in ground-based radar coverage and rain gauge networks in the U.S., geostationary satellite quantitative precipitation estimates (QPEs) such as the Self-Calibrating Multivariate Precipitation Retrievals (SCaMPR) can be used to fill in both the spatial and temporal gaps of ground-based measurements. Additionally, with the launch of GOES-R, the temporal resolution of satellite QPEs may be comparable to that of Weather Service Radar-1988 Doppler (WSR-88D) volume scans as GOES images will be available every five minutes. However, while satellite QPEs have strengths in spatial coverage and temporal resolution, they face limitations particularly during convective events. Deep Convective Systems (DCSs) have large cloud shields with similar brightness temperatures (BTs) over nearly the entire system, but widely varying precipitation rates beneath these clouds. Geostationary satellite QPEs relying on the indirect relationship between BTs and precipitation rates often suffer from large errors because anvil regions (little/no precipitation) cannot be distinguished from rain-cores (heavy precipitation) using only BTs. However, a combination of BTs and optical depth (τ) has been found to reduce overestimates of precipitation in anvil regions. A new rain mask algorithm incorporating both τ and BTs has been developed, and its application to the existing SCaMPR algorithm was evaluated. Here, the performance of the modified SCaMPR was evaluated using traditional skill scores and a more detailed analysis of performance in individual DCS components by utilizing the Feng et al. (2012) classification algorithm. SCaMPR estimates with the new rain mask applied benefited from significantly reduced overestimates of precipitation in anvil regions and overall improvements in skill scores.

54 ENVIRONMENTAL SCIENCES↗

Time recovery measurements using operational GOES and transit satellites

Results of regular monitoring of both the GOES and TRANSIT timing signals over a number of months at the National Bureau of Standards (NBS), Boulder, Colorado are presented. The TRANSIT results include an analysis of how received timing accuracy and stability are affected by: (1) averaging over varying numbers of satellite passes; (2) averaging over different combinations of the five available satellites; (3) using several independent receivers of the same type; and (4) application of published corrections to the received data. Based on monitoring experience to date at NBS, some pros and cons of using each of the available operational systems are discussed. Updated information on recent improvements incorporated into the GOES time code generation and monitoring system at Wallops Island, Virginia is also included.

Beehler, R. E.↗

Flight and ground tests of a GOES satellite time receiver for satellite communications applications

A satellite time receiver was tested in various environmental conditions during the past year. The commercial receiver designed to work with the National Oceanic and Atmospheric Administration's (NOAA) Geostationary Operational Environmental Satellites (GOES). The test program included operation at low elevation during flight in a military cargo aircraft and long term comparison with laboratory standards. The GOES satellite time receiver offers an opportunity to provide easy wide area coverage synchronization at low cost.

Swanson, R. L.↗

Cloud cover estimation: Use of GOES imagery in development of cloud cover data base for insolation assessment

The potential of using digital satellite data to establish a cloud cover data base for the United States, one that would provide detailed information on the temporal and spatial variability of cloud development are studied. Key elements include: (1) interfacing GOES data from the University of Wisconsin Meteorological Data Facility with the Jet Propulsion Laboratory's VICAR image processing system and IBIS geographic information system; (2) creation of a registered multitemporal GOES data base; (3) development of a simple normalization model to compensate for sun angle; (4) creation of a variable size georeference grid that provides detailed cloud information in selected areas and summarized information in other areas; and (5) development of a cloud/shadow model which details the percentage of each grid cell that is cloud and shadow covered, and the percentage of cloud or shadow opacity. In addition, comparison of model calculations of insolation with measured values at selected test sites was accomplished, as well as development of preliminary requirements for a large scale data base of cloud cover statistics.

Huning, J. R.↗

The inference of tropical cyclone dynamics using GOES VISSR/VAS data

The sequence of events observed during tropical cyclone Emily, was suggested as a possible mechanism for cyclogenesis. Geostationary Operational Environmental Satellite (GOES) East VISSR/VAS sensors were used. The VISSR visible imagery obtained every 15 minutes was used to define the low tropospheric cyclonic vortex and upper tropospheric horizontal convergence. The VAS water vapor (channels 9 and 10) and carbon dioxide (channels 3 and 4) channels were used to infer upper and middle tropospheric subsidence by monitoring the Adiabatic compressional drying and warming, respectively, occurring within this layer. Evidence of an existing lower tropospheric cyclonic vortex was seen. The satellite derived wind vectors (length of vector is proportional to wind velocity, where the strongest winds were approximately 35 knots) are superimposed on the GOES visible image of tropical storm Emily. Vectors and low level clouds depict the center of the cyclonic vortex immediately south of the large convective cell in the center of the image. Upper tropospheric cloud tracers and rawinsonde reports along the Eastern United States suggest that the southwesterly environmental upper atmospheric flow is converging with the outflow from the convective cell north of the vortex.

Rodgers, E. B.↗

GOES satellite time code dissemination

The GOES time code system, the performance achieved to date, and some potential improvements in the future are discussed. The disseminated time code is originated from a triply redundant set of atomic standards, time code generators and related equipment maintained by NBS at NOAA's Wallops Island, VA satellite control facility. It is relayed by two GOES satellites located at 75 W and 135 W longitude on a continuous basis to users within North and South America (with overlapping coverage) and well out into the Atlantic and Pacific ocean areas. Downlink frequencies are near 468 MHz. The signals from both satellites are monitored and controlled from the NBS labs at Boulder, CO with additional monitoring input from geographically separated receivers in Washington, D.C. and Hawaii. Performance experience with the received time codes for periods ranging from several years to one day is discussed. Results are also presented for simultaneous, common-view reception by co-located receivers and by receivers separated by several thousand kilometers.

Beehler, R. E.↗

Expressions to determine temperatures and emission measures for solar X-ray events from GOES measurements

Expressions which give the effective color temperatures and corresponding emission measures for solar X-ray events observed with instruments onboard any of the GOES satellites are developed. Theoretical spectra were used to simulate the solar X-ray input at a variety of plasma temperatures. These spectra were folded through the wavelength dependent transfer functions for the two GOES detectors. The resulting detector responses and their ratio as a function of plasma temperature were then fit with simple analytic curves. Over the entire range between 5 and 30 million degrees, these fits reproduce the calculated color temperatures within 2% and the calculated emission measures within 5%. With the theoretical spectra, similar expressions for any pair of broadband X-ray detectors whose sensitivities are limited to wavelengths between 0.2 and 100 A are calculable.

Thomas, R. J.↗

Diurnal variability of regional cloud and clear-sky radiative parameters derived from GOES data. I - Analysis method. II - November 1978 cloud distributions. III - November 1978 radiative parameters

Cloud cover is one of the most important variables affecting the earth radiation budget (ERB) and, ultimately, the global climate. The present investigation is concerned with several aspects of the effects of extended cloudiness, taking into account hourly visible and infrared data from the Geostationary Operational Environmental Satelite (GOES). A methodology called the hybrid bispectral threshold method is developed to extract regional cloud amounts at three levels in the atmosphere, effective cloud-top temperatures, clear-sky temperature and cloud and clear-sky visible reflectance characteristics from GOES data. The diurnal variations are examined in low, middle, high, and total cloudiness determined with this methodology for November 1978. The bulk, broadband radiative properties of the resultant cloud and clear-sky data are estimated to determine the possible effect of the diurnal variability of regional cloudiness on the interpretation of ERB measurements.

Minnis, P.↗

Expressions to determine temperatures and emission measures for solar X-ray events from GOES measurements

Expressions which give the effective color temperatures and corresponding emission measures for solar X-ray events observed with instruments onboard any of the GOES satellites are developed. Theoretical spectra were used to simulate the solar X-ray input at a variety of plasma temperatures. These spectra were folded through the wavelength dependent transfer functions for the two GOES detectors. The resulting detector responses and their ratio as a function of plasma temperature were then fit with simple analytic curves. Over the entire range between 5 and 30 million degrees, these fits reproduce the calculated color temperatures within 2 percent and the calculated emission measures within 5 percent. With the theoretical spectra, similar expressions for any pair of broadband X-ray detectors whose sensitivities are limited to wavelengths between 0.2 and 100 A are calculable.

Thomas, R. J.↗

Estimation of precipitation from GOES IR imagery during FGGE: Application to diagnostic studies

The objectives were to (1) develop a method of estimating open-ocean rainfall and associated latent heat release via GOES IR satellite imagery; (2) to use remote precipitation estimates to investigate the role of diabatic forcing in the maintenance of the South Pacific Convergence Zone (SPCZ) during FGGE SOP-1/; and (3) to assess the significance of non-quasigeostrophic transports of energy in several cyclogenetic events preceding the development of a North Atlantic blocking episode during FGGE SOP-1. The bulk of the early FY-85 work was directed toward development of the single pixel indexing technique (SPI) which assigns a rain rate to GOES IR black-body temperatures, T sub b, via a non-linear statistical relationship developed with raingauge measurements. The method was tested against radar-derived rainfall during GATE raingauge measurements over coastal North Carolina and island stations in the South Pacific Ocean. Skill was found comparable to Arkin's method (1979 MWR) in convective situations. The results suggest that transferring a rain algorithm from one oceanic regime to another may not require substantial modification of coefficients or tunable parameters. Twelve H mean rainfall amounts were produced for the region bounded by 10 deg. N, 50 deg. S, 120 deg W and 170 deg. E during the period January 10 to 16, 1979. These estimates constitute a basic input to diagnostic calculations of diabatic heating over the SPCZ region. ECMWF level III-b data analyses was used to compute several components of the APE balance in the South Pacific during the period January 10 to 18, 1979.

Robertson, F. R.↗

Predicting the performance of solar illuminated thermal louvers for the GOES I, J, K instruments

The new series of Geostationary Operational Environmental Satellites (GOES I,J,K,L/M) will have two earth viewing optical instruments which use passive, bi-metallic actuated, blade-type louvers for their thermal control. GOES is a three-axis stabilized spacecraft in geostationary orbit, which means that sun can enter the instrument apertures for several hours before and after local midnight. The solar heat absorbed in the instruments causes the louvers to open thus allowing the radiators to reject the heat. These louvered radiators are located on the north face of the instruments. To perform thermal analyses of the instruments, a modeling method was needed for predicting the thermal characteristics of the louvers. This task was complicated by the fact that sun shines on the louvers during the summer season. A Monte Carlo analytical technique was used to develop absorbed power and effective emissivity tables for the louvers. These tables could be used with the instrument math models to predict the thermal behavior of the instruments. Data from the Monte Carlo analysis showed that solar entrapment could have a significant effect on the heat rejection capability of the louvered radiators.

Mengers, David↗

GOES satellite imagery for aircraft-based studies of tropospheric chemistry in remote regions

This paper discusses the benefits of real-time high resolution GOES satellite imagery, radar, and other meteorological input transmitted to a remote field site where this type of meteorological support is normally not available. Information describing the equipment used to maintain the data flow between NASA-LaRC and the remote site is given. Operational examples demonstrate the usefulness of real-time data in both pre-flight planning and during the actual missions. It is shown that the availability of current high resolution GOES images and the ability to animate and enhance these images allowed near-real-time guidance of an aircraft-based field mission.

Shipham, M. C.↗