Polar-orbiting Operational Environmental Satellite System Research Articles

VIIRS Night-Time Light Image in the Spatial Structure Identification of Banyuwangi Regency

A spatial structure is a hierarchical arrangement of settlement centers and a network system of infrastructure and facilities that support the community’s socio-economic activities. Spatial structure is important because the city’s rapid growth requires regional service center planning. In general, the method for determining the spatial structure uses the Centrality Index (IS) with a variable number of facilities, infrastructure, and people to obtain a hierarchical arrangement of regional service centers. However, this method is often constrained by data limitations, so in this study remote sensing technology was used through night light imagery in identifying potential centers. This study used the Visible and Infrared Imaging Radiometer Suite (VIIRS) sensor, one of the sensors carried by the Suomi-NPP (National Polar-orbiting Operational Environmental Satellite System Preparatory Project) satellite. Identification is done by overlaying the night light image with the existing spatial structure to produce potential centers. Based on the analysis results, eight classifications are based on the light emission interval class, where the higher the class, the higher the light emission value, which indicates the potential for a new center. The Pesanggaran sub-district is in class eight, the Tegaldimo sub-district is in class six, and the Banyuwangi sub-district is in class one.

Intercomparison of Landsat OLI and JPSS VIIRS Using a Combination of RadCalNet Sites as a Common Reference

Independent radiometric data collected from multiple ground sites as part of vicarious calibration activities can be combined to harmonize the data products of Earth observation sensors with different temporal, spectral, and spatial resolutions. Recent coordinated international efforts for open fiducial reference measurements have provided the worldwide user community with new ways to explore the calibration and harmonization of data produced by the sensors. To be correct, the results from each ground system must be traceable to the same well-understood standard system, and ideally to the international system of units (SI). Additionally, the calibration test site should be homogeneous over an area larger than the spatial resolutions of each sensor, so that ground measurements are representative of the area seen by the sensors being calibrated. Here, we use a combination of independent and SI-traceable radiometric data provided from two sites of the Radiometric Calibration Network (RadCalNet) to compare the radiometric response of sensors with different spectral and spatial resolutions that operate on different orbits. These sensors are Operational Land Imagers (OLI) of the Landsat-8 and Landsat-9 missions, and Visible Infrared Imaging Radiometer Suites (VIIRS) of the Suomi-National Polar-Orbiting Operational Environmental Satellite System Preparatory Project (SNPP) and Joint Polar Satellite System-1 (JPSS-1) missions. The sensor radiometric responses are compared via temporal averaging of the ratios of top-of-atmosphere reflectance values for each sensor to those reported by RadCalNet. Our intercomparison results show that these on-orbit sensors are calibrated within their absolute radiometric uncertainties. The absolute radiometric uncertainties of single-sensor over single-site intercomparisons at 550 nm is between 5% and 6%. Having the opportunity to look at the intercomparison results of Landsat-9 OLI compared to each calibration site individually and then in combination allowed us to investigate potential systematic site-dependent biases. We did not observe significant site-dependent biases in the behavior of the four on-orbit sensors compared to the calibration sites. The absolute radiometric uncertainty of a single sensor over multiple-site intercomparisons at 550 nm is 5.4%. We further investigated site-dependent biases by looking at the double-ratio calibration coefficients of the on-orbit sensors, calculated with reference to those sites.

Using ecosystem service supply and ecosystem sensitivity to identify landscape ecology security patterns in the Lanzhou-Xining urban agglomeration, China

The construction of an ecological security pattern (ESP) is an important way to ensure regional ecological security and to achieve sustainable regional development. It is also one of the hotspot topics of landscape ecology research. This paper identifies the ecological source through the evaluation of the ecosystem service and ecosystem sensitivity of the Lanzhou-Xining (Lan-Xi) urban agglomeration. The minimum cumulative resistance (MCR) model modified by night light data NPP/VIIRS (National Polar-orbiting Operational Environmental Satellite System Preparatory Project/Visible Infrared Imaging Radiometer Suite) was used to measure the relative resistance of the materials and energy circulation between the source areas, and to establish the resistance surface of the ecological source area expansion. Then ecological corridors were identified based on ecological sources and resistance surface. The ecological strategic node is the ecological fragile point in the ecological corridors. The ecological strategic node is identified with hydrological module by superimposing the “ridge line” of cumulative ecological resistance with the ecological corridor. Combined with ecological sources, corridors and strategic nodes, the ESP of the Lan-Xi urban agglomeration can be constructed. The ecological source of the Lan-Xi urban agglomeration accounts for 28.42% of the total area, most of which is distributed within Qinghai Province. The nature reserves in the area are all located within the ecological source area. A total of 41 potential ecological corridors have been identified in the study area. The total length of the potential corridors is 1201.03 km, comprising 23 source corridors and 18 radiation corridors. There are 30 strategic nodes identified in the Lan-Xi urban agglomeration. These locations are the most vulnerable areas of the ecological corridors. Ecological engineering should be applied in the construction of corridors. Affected by the ecological source, the potential ecological corridor extends from the northwest to the southeast, which is basically consistent with the direction trend of the mountains in the region.

A physical algorithm for precipitable water vapour retrieval over land using passive microwave observations

ABSTRACT Precipitable water vapour (PWV) plays an important role in weather prediction, hydrological cycles and climate change. In this study, a physics-based algorithm was proposed to retrieve PWV over land using satellite passive microwave observations near 165.50 GHz and 183.31 GHz, which have higher spatial resolution and lower sensitivity to land surface emissivity than low-frequency channels. The algorithm uses a perturbation formulation of simplified radiative transfer equation to derive PWV and at-surface brightness temperature (BT) in 165.50 GHz simultaneously. It directly derives the at-surface BT instead of land surface temperature, so the algorithm needs no prior information of surface emissivity. Sensitivity analysis and retrieval experiments from simulated data were carried out for Advanced Technology Microwave Sounder (ATMS) onboard the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) satellite. The results showed that the algorithm using ATMS channels 17, 18 and 19 measurements can significantly reduce the PWV retrieval errors caused by surface emissivity uncertainty. The coefficient of determination (R 2), root-mean-square error (RMSE), and bias of the retrieved PWV from ATMS data by the proposed algorithm and SuomiNet Global Positioning System (GPS) PWV were 0.90, 0.43 cm and −0.02 cm, respectively. In addition, the Visible Infrared Imaging Radiometer Suite (VIIRS) cloud products were used to evaluate the effects of cloud on the PWV retrievals. The results showed that the presence of cloud does not decrease the accuracy of the PWV retrievals.

Architectural Concept of Disaggregation of Space Systems: Application to Weather Satellites

In the next decades, researchers and global decision makers will rely on new emerging technologies, architectural constructs, and ideas to reshape the space enterprise to meet many of their needs for global weather observation and information. One such new architectural concept is the disaggregation of space capabilities across multiple numbers of systems. Disaggregation has the potential to minimize cost per operational year and improve the system resiliency. Due to the cancellation of the National Polar-Orbiting Operational Environmental Satellite System program in 2010, both the U.S.’s National Oceanic and Atmospheric Administration and Department of Defense have started to investigate different acquisition approaches through the use of disaggregation to reduce the total program acquisition cost. This paper investigates the cost impacts of disaggregation across time for the weather follow-on systems. A merged system dynamics and trade space exploration technique is developed for the mission area of weather and climate sensing satellite systems. The merged model is simulated for both the systems to look at long-term trends and examine different levels of disaggregation across time. The impact of complexity on the cost metric is analyzed through the examination of different policies. Five different disaggregated implementations, each with a unique way of adding capability across future generations, are considered for the analysis of weather and climate sensing satellites. The model suggests a set of disaggregated approaches that, although not potentially cost effective, are able to reach higher efficiency and deliver additional capability to orbit in contrast to fully aggregated buses.

Intercalibration of Cross-Track Scanners in GPM Constellation

This paper discusses the intersatellite radiometric calibration for microwave sounders in support of NASA’s Global Precipitation Measurement (GPM) mission. This paper is an extension of previous GPM Intersatellite Calibration Working Group work, which assesses the robustness of the Central Florida Remote Sensing Laboratory “double difference” technique for sounders intercalibration. In this paper, we will analyze the intercalibration between the Advanced Technology Microwave Sounder on board the National Polar-orbiting Operational Environmental Satellite System Preparatory Project, the Microwave Humidity Sounder on board the MetOp-A and MetOp-B and NOAA-18 and NOAA-19, and the Sondeur Atmospherique du Profil d’Humidite Intertropicale par Radiometrie sounder onboard the Megha-Tropiques satellite. The sensitivity of the calibration to the geophysical parameters and incidence angles is investigated using two years data. Here, it is observed that a reliable intercalibration can be made only when the path lengths of the two sensors are similar, so when matching the scan angles for the two sensors, the sensitivity of the biases upon the water vapor profiles is significantly reduced.

CHLOROPHYLL-A CONCENTRATIONS ESTIMATION FROM AQUA-MODIS AND VIIRS-NPP SATELLITE SENSORS IN SOUTH JAVA SEA WATERS

This study aimed to estimate the concentration of chlorophyll-a from satellite imagery of National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) in the south Java Sea waters and compare it to the concentrations of chlorophyll-a estimation result from the MODIS-Aqua satellite. NPP satellite had Visible/Infrared Imager Radiometer Suite (VIIRS) sensors which performance was same as Moderate Resolution Imaging Spectroradiometer (MODIS) sensor with a better spatial resolution. This study used daily satellite imagery of VIIRS-NPP for the period of September 2012 to August 2013. The algorithm that was used to estimate the concentration of chlorophyll-a was Ocean Color 3-band ratio (OC-3). The results showed that the spatial distribution pattern of chlorophyll-a concentration between VIIRS - NPP sensor and MODIS had the same pattern, but the estimation of chlorophyll-a concentration from the MODIS sensor was higher than VIIRS -NPP sensor. The concentration of chlorophyll-a showed that there were spatial and temporal variation in the south Java Sea waters. Generally, concentrations of chlorophyll-a was higher in East monsoon than West monsoon.

A comparison between three surface type data sets adopted by the community radiative transfer model

ABSTRACTThe accuracy of simulated radiances for surface-sensitive visible and infrared channels is affected by the specification of surface type. The current version of Community Radiative Transfer Model (CRTM) employs three surface type data sets, which are referred to as the National Polar-orbiting Operational Environmental Satellite System (NPOESS), the U. S. Geological Survey (USGS), and the International Geosphere-Biosphere Programme (IGBP) data sets, respectively. In this study, the consistencies and discrepancies among these three surface type data sets are examined. The surface type is specified consistently among the three data sets in equatorial and polar regions, but not in other regions especially around 60° N. The desert and snow types have the highest consistency among the three surface type data sets. The tundra in the IGBP data set, the needle-leaf forecast and mixed forest in the NPOESS data set, and the mixed forest in the USGS data set have the greatest discrepancy from the other two data sets. Finally, a canonical case is used to demonstrate that the impacts of the three surface type datasets on CRTM simulations are significant, pointing to a need for a rigorously defined surface type data set.

Estimation of planetary boundary layer height using Suomi NPP-CrIS soundings

ABSTRACTThe study estimates planetary boundary layer height (PBLH) using temperature and humidity profiles from Cross-Track Infrared Sounder (CrIS) onboard Suomi National Polar-Orbiting Operational Environmental Satellite System Preparatory Project (SNPP). PBLH is estimated using six different methods and also using an integrated approach. PBLH estimated from SNNP-CrIS soundings by the integrated approach is compared with the PBLH values estimated using atmospheric profiles from radiosonde ascents and Constellation Observing System for Meteorology Ionosphere and Climate-radio occultation (COSMIC-RO) measurements. Analysis shows reasonable agreement of PBLH values from SNPP-CrIS soundings with those from radiosonde measurements and COSMIC-RO retrievals, thus revealing the capability of atmospheric profiles from SNNP-CrIS for the characterization of planetary boundary layer (PBL) with excellent spatial resolution and coverage. PBLH from SNNP-CrIS soundings are observed to be overestimated by around 336 m compared to the estimates from radiosonde ascends and is partly attributed to the difference in time of observations and coarse vertical resolution of the SNPP-CrIS-derived profiles. Compared to the estimates from SNPP-CrIS soundings, PBLH values from COSMIC-RO profiles are overestimated by around 596 m. Estimates from SNPP-CrIS soundings, through the integrated approach, are further used to examine the spatial and seasonal variations of PBLH over the Indian landmass. PBLH is observed highest in pre-monsoon and lowest in winter over most of the regions. Due to rainfall and associated changes in lower atmosphere and surface characteristics, PBLH is observed shallow during monsoon.

A Framework for Studying Cost Growth on Complex Acquisition Programs

The government acquisition system is consistently plagued by cost growth and by attempts at acquisition reform. Despite these persistent challenges, the academic community lacks a methodology for studying complex acquisition programs both in-depth and longitudinally throughout their life cycles. In this paper, we present a framework for studying complex acquisition programs that provides researchers with a strategy for systematically studying cost growth mechanisms. The proposed framework provides a means to identify specific technical and organizational mechanisms for cost growth, to organize those mechanisms using design structure matrices, and to observe the evolution of those mechanisms throughout a program's life cycle. To illustrate the utility of our framework, we apply it to analyze a case study of the National Polar-orbiting Operational Environmental Satellite System NPOESS program. Ultimately, we demonstrate that the framework enables us to generate unique insights into the mechanisms that induced cost growth on NPOESS and that were unacknowledged by previous studies. Specifically, we observed that complexity was injected into the technical system well before the program's cost estimates began to increase and that it was the complexity of the NPOESS organization that hindered the program's ability to effectively estimate and to manage its costs.

Model-Based Conceptual Design Optimization Methods: Disaggregated Weather System Follow-On

The future of space-based defense weather systems is uncertain due to the cancellation of the National Polar-Orbiting Operational Environmental Satellite System and Defense Weather Satellite System programs. The U.S. Department of Defense Weather Satellite Follow-On program has been identified as the follow-on program and a potential pathfinder for the concept of disaggregation. The concept of disaggregation has the potential to reduce costs and increase system resiliency. However, current research literature does not address a systematic method for performing conceptual trades between large multifunction and small functionally cohesive spacecraft. A multifunction/multiorbit disaggregated space-system optimization methodology is proposed and applied to the weather system follow-on conceptual architecture problem. Real-coded mixed-integer optimization techniques are implemented to identify, assess, and compare alternative space-based weather system conceptual architectures. The resulting cost and performance figures of merit are analyzed to assess disaggregated space-based weather constellation cost effectiveness. The potential estimated life-cycle cost savings of approximately 3 billion U.S. dollars are modeled for a disaggregated weather system follow-on program versus a Defense Weather Satellite System analogous architecture. The resulting analysis is intended to demonstrate the applicability of the disaggregated integral system concept optimization methodology to assess multifunction, multiorbit disaggregation problems.

Cloudy Forecast for Weather Satellite Data

![Figure][1] NPOESS Preparatory Project satellite (artist's rendition). CREDIT: NOAA IN SPACE COLLECTION In the News Focus story “Weather forecasts slowly clearing up” (9 November, p. [734][2]), R. Kerr nicely summarizes how the growing improvement in prediction is coming from a focus on “more computer power, the assimilation of radar observations, and more physically realistic models.” He emphasizes that better assimilation of satellite data is a key element of improved forecasting. Unfortunately, these potential improvements will have little effect on forecasts if the basic data set from the existing polar-orbiting weather satellite system is not available. In a report issued in June 2012 ([ 1 ][3]), the U.S. Government Accountability Office noted that “data from this system is the predominant input to numerical weather prediction models” and warned that “there will likely be a gap in satellite data lasting 17 to 53 months” when the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project satellite ceases operations and NOAA's new satellite system (the Joint Polar Satellite System) launches. The report also notes that there are “potential satellite data gaps in DOD [Department of Defense] and European polar satellite programs which provide supplementary information to NOAA forecasts.” These gaps are a grave problem and would seriously degrade weather forecasts. Therefore, the agencies responsible for weather forecasting—NOAA, DOD, and NASA—should make filling the polar satellite data gaps the first priority in order to ensure that future forecasts are as good as possible. 1. [↵][4] U.S. GAO, “Polar-orbiting environmental satellites: Changing requirements, technical issues, and looming data gaps require focused attention,” GAO-12-604 (2012); [www.gao.gov/products/GAO-12-604][5]. [1]: pending:yes [2]: /lookup/doi/10.1126/science.338.6108.734 [3]: #ref-1 [4]: #xref-ref-1-1 View reference 1 in text [5]: http://www.gao.gov/products/GAO-12-604

Industry and Government Space Weather Experts Meet

The fifth annual NOAA Space Weather Prediction Center (SWPC)-Commercial Space Weather Interest Group (CSWIG) Summit was held on 28 April 2011 in Boulder, Colo., in association with the 2011 Space Weather Workshop. Interest was high, in the United States and internationally, in potential space weather impacts on many aspects of everyday life because of the increased vulnerability of technological systems and the possibility that a major space weather event may occur as the twenty-fourth solar cycle begins to progress toward solar maximum. Industry and government space weather experts participated in the summit. Devrie Intriligator (Carmel Research Center, Inc.) and W. Kent Tobiska (Space Environment Technologies (SET)) served as cochairs. Tom Bogdan, Director of SWPC, summarized SWPC’s current fiscal situation and future plans. SWPC has been successful in educating members of the executive branch and other government officials about space weather. President Obama’s proposed fiscal year (FY) 2012 budget includes Department of Defense and NOAA funding for the Deep Space Climate Observatory (DSCOVR), the replacement for the Advanced Composition Explorer (ACE) spacecraft, which warns of approaching interplanetary disturbances from the Sun. It is crucial for Congress to appropriate this funding if DSCOVR is to be launched on schedule in 2014. The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-2) mission is also in the proposed FY 2012 budget. Starting in early fall 2011, SWPC is planning to have two forecasters on duty 24 hours a day, 7 days a week. SWPC’s top operational priorities include an improved WangSheeleyArge (WSA) model of the Sun/solar wind interface and a Ground Induced Current regional model. A high priority is improved forecasting of the interplanetary magnetic field characteristics of a coronal mass ejection that hits Earth. David Bouwer (SET) summarized SWPC’s External Space Weather Data Store (E-SWDS) and other data/model sources. E-SWDS is the most reliable data source with the fewest changes/interruptions in service, format, and parameters. CSWIG looks forward to when E-SWDS also will include improved model outputs (e.g., ENLIL, WSA, etc.). Intriligator summarized concerns on the quality and quantity of future data including those from ACE and National Polar-Orbiting Operational Environmental Satellite System (NPOESS) replacements, the Geostationary Operational Environmental Satellite (GOES), etc. Space weather research, operations, and forecasts are data limited, and longterm monitoring of solar, interplanetary, and near-Earth regions is crucial. NOAA is tasked with this monitoring. Stable funding of long-term spacecraft lines (e.g., GOES) is needed. Michael Bonadonna (Office of the Federal Coordinator for Meteorology (OFCM)) updated the group on the National Space Weather Program (NSWP) and OFCM activities. One of the near-term priorities of OFCM is to improve its ability to work with the commercial sector. At present, there is no mechanism for the commercial sector to participate in the NSWP Council or other high-level NSWP activities. The Office of Science and Technology Policy has requested that NSWP assess U.S. space weather capabilities now and 10 years in the future. Tobiska discussed CSWIG participation in software test beds and Small Business Innovative Research opportunities as ways of leveraging funding. He also discussed moving toward space weather common practices and a quality assurance program including standards as developed by the American Institute of Aeronautics and Astronautics (http://spacewx.com, see the “Standards” link under “Resources”). Geoff Crowley (Atmospheric and Space Technology Research Associates) reported on the American Commercial Space Weather Association (ACSWA), the space weather association that was unanimously formed last year at the SWPCCSWIG Summit. The ACSWA executive committee (Crowley, Intriligator, Robert Schunk, and Tobiska) had earlier drafted the mission statement for ACSWA and established a Web site (http://sw01.spaceweather.usu.edu/ACSWA/ landing.html), which was unveiled at the summit meeting. Bonadonna and Bogdan enthusiastically supported ACSWA. Genene Fisher

Automated Lightning Flash Detection in Nighttime Visible Satellite Data

Abstract The Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) nighttime visible channel was designed to detect earth–atmosphere features under conditions of low illumination (e.g., near the solar terminator or via moonlight reflection). However, this sensor also detects visible light emissions from various terrestrial sources (both natural and anthropogenic), including lightning-illuminated thunderstorm tops. This research presents an automated technique for objectively identifying and enhancing the bright steaks associated with lightning flashes, even in the presence of lunar illumination, derived from OLS imagery. A line-directional filter is applied to the data in order to identify lightning strike features and an associated false color imagery product enhances this information while minimizing false alarms. Comparisons of this satellite product to U.S. National Lightning Detection Network (NLDN) data in one case as well as to a lightning mapping array (LMA) in another case demonstrate general consistency to within the expected limits of detection. This algorithm is potentially useful in either finding or confirming electrically active storms anywhere on the globe, particularly those occurring in remote areas where surface-based observations are not available. Additionally, the OLS nighttime visible sensor provides heritage data for examining the potential usefulness of the Visible-Infrared Imager-Radiometer Suite (VIIRS) Day/Night Band (DNB) on future satellites including the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP). The VIIRS DNB will offer several improvements to the legacy OLS nighttime visible channel, including full calibration and collocation with 21 narrowband spectral channels.

Comparing MODIS and AIRS Infrared-Based Cloud Retrievals

AbstractComparisons are described for infrared-derived cloud products retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) using measured spatial response functions obtained from prelaunch AIRS calibration. One full day (1 January 2005) of global collection-5 MODIS and version-5 AIRS retrievals of cloud-top temperature Tc, effective cloud fraction f, and derived effective brightness temperature Tb,e is investigated. Comparisons of Tb,e demonstrate that MODIS and AIRS are essentially radiatively consistent and that MODIS Tb,e is 0.62 K higher than AIRS Tb,e for all scenes, increasing to 1.43 K for cloud described by AIRS as single layer and decreasing to 0.50 K for two-layer clouds. Somewhat larger differences in Tc and f are observed between the two instruments. The magnitudes of differences depend partly on whether MODIS uses a CO2-slicing or 11-μm brightness temperature window retrieval method. Some cloud- and regime-type differences and similarities between AIRS and MODIS cloud products are traceable to the assumptions made about the number of cloud layers in AIRS and also to the MODIS retrieval method. This (partially) holistic comparison approach should be useful for ongoing algorithm refinements, rigorous assessments of climate applicability, and establishment of the capability of synergistic MODIS and AIRS retrievals for improved cloud quantities and also should be useful for future observations to be made by the National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP).

Solar Sensor Grounded on Revamped Satellite Program

Last week's announcement that the first spacecraft of the newly reconfigured program previously known as the National Polar-orbiting Operational Environmental Satellite System wouldn't be able to measure the intensity of sunlight has left U.S. climate scientists feeling out in the cold.

NPOESS Precipitation Retrievals Using the ATMS Passive Microwave Spectrometer

This letter evaluates the ability of the U.S. National Polar-orbiting Operational Environmental Satellite System 22-channel Advanced Technology Microwave Sounder (ATMS) to retrieve surface precipitation rates (millimeters per hour); water path estimates for rain, snow, and graupel (millimeters); and peak vertical wind (convective strength, meters per second). Simulated retrieval accuracies for ATMS were compared to those for its predecessor the Advanced Microwave Sounding Unit (AMSU), both of which sample the 23- to 190-GHz spectrum. ATMS retrieves all precipitation parameters up to ~ 25% more accurately than AMSU except for cloud ice and snow water paths, which are comparable. Image sharpening of the ATMS Nyquist-sampled observations below 90 GHz further improves the recovery of small features but amplifies noise so that the benefits are restricted primarily to finely structured convective systems.

NPOESS

The United States is merging its two polar-orbiting operational environmental satellite programs operated by the Department of Commerce and the Department of Defense into a single system, which is called the National Polar-orbiting Operational Environmental Satellite System (NPOESS). During the next decade, NPOESS will provide global operational data to meet many of the needs of weather forecasters, climate researchers, and global decision makers for remotely sensed Earth science data and global environmental monitoring. The NPOESS Preparatory Project (NPP) will be launched in 2011 as a precursor to NPOESS to reduce final development risks for NPOESS and to provide continuity of global imaging and atmospheric sounding data from the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) missions. Beginning in 2014, NPOESS spacecraft will be launched into an afternoon orbit and in 2016 into an early-morning orbit to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Meteorological Operation (MetOp) spacecraft will complement NPOESS in a midmorning orbit. The joint constellation will provide global coverage with a data refresh rate of approximately four hours. NPOESS will observe more phenomena simultaneously from space and deliver a data volume significantly greater than its operational predecessors with substantially improved data delivery to users. Higher-resolution (spatial and spectral) and more accurate imaging and atmospheric sounding data will enable improvements in short- to medium-range weather forecasts. Multispectral and hyperspectral instruments on NPOESS will provide global imagery and sounding products useful to the forecaster that are complementary to those available from geostationary satellites. NPOESS will support the operational needs of meteorological, oceanographic, environmental, climatic, and space environmental remote sensing programs and provide continuity of data for climate researchers. This article that describes NPOESS was completed and accepted for publication prior to the White House decision in February 2010 ordering a major restructuring of the NPOESS program. The Department of Commerce will now assume primary responsibility for the afternoon polar-orbiting operational environmental satellite orbit and the Department of Defense will take primary responsibility for the early morning orbit. However, NPP, as described in this article, is still scheduled to be launched in 2011. Several of the instruments and program elements described in this article are also likely to be carried forward into future U.S. polar-orbiting operational environmental satellite missions.

Differentiating between Clouds and Heavy Aerosols in Sun-Glint Regions

Abstract An approach is presented to distinguish between clouds and heavy aerosols in sun-glint regions with automated cloud classification algorithms developed for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) program. The approach extends the applicability of an algorithm that has already been applied successfully in areas outside the geometric and wind-induced sun-glint areas of the earth over both land and water surfaces. The successful application of this approach to include sun-glint regions requires an accurate cloud phase analysis, which can be degraded, especially in regions of sun glint, because of poorly calibrated radiances of the National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Consequently, procedures have been developed to replace bad MODIS level 1B (L1B) data, which may result from saturation, dead/noisy detectors, or data dropouts, with radiometrically reliable values to create the Visible Infrared Imager Radiometer Suite (VIIRS) proxy sensor data records (SDRs). Cloud phase analyses produced by the NPOESS VIIRS cloud mask (VCM) algorithm using these modified VIIRS proxy SDRs show excellent agreement with features observed in color composites of MODIS imagery. In addition, the improved logic in the VCM algorithm provides a new capability to differentiate between clouds and heavy aerosols within the sun-glint cone. This ability to differentiate between clouds and heavy aerosols in strong sun-glint regions is demonstrated using MODIS data collected during the recent fires that burned extensive areas in southern Australia. Comparisons between heavy aerosols identified by the VCM algorithm with imagery and heritage data products show the effectiveness of the new procedures using the modified VIIRS proxy SDRs. It is concluded that it is feasible to accurately detect clouds, identify cloud phase, and distinguish between clouds and heavy aerosol using a single cloud mask algorithm, even in extensive sun-glint regions.

Clear and cloudy sky investigations using Raman lidar and airborne interferometric measures from the European AQUA Thermodynamic Experiment

A dataset of ground, airborne and satellite data was measured during the comprehensive 2004 EAQUATE (European AQUA Thermodynamic Experiment) Italian campaign. We have used ground based and airborne data to evaluate the consistency of Raman lidar temperature and humidity profiles with NAST-I (The National Polar-orbiting Operational Environmental Satellite System Airborne Sounder Testbed-Interferometer) spectral radiance measurements in clear conditions, and the consistency of total cloud optical depth measured by the Raman lidar with the same quantity retrieved from NAST-I measurements. Lidar measurement of temperature and humidity profiles can resolve short time changes in mixing ratio due to its high time resolution. Brightness temperature simulations of clear sky, performed using lidar-derived profiles, are within 1 K difference with respect to data when averages over 25 cm − 1 and emission from layers below 7 km are considered. High spectral resolution simulations agree with NAST-I measurements with a mean percentage difference less than 0.5% in the whole ν 2 water vapour band. The simulations in cloudy conditions are based on crystal properties obtained assuming either an appropriate mixture of crystal habits (that for the first time is tested against high spectral resolution measurements) or pristine solid columns. Lidar-derived cloud base and top altitudes and lidar temperature and humidity profiles are exploited, for the first time, as inputs in a recently developed infrared cloud properties retrieval procedure. Total cloud optical depths, retrieved from 800 to 980 cm − 1 NAST-I radiances, have values that, when converted to short-wave wavelengths, are in the range 0.05–2.2 and agree with lidar measurements to within experimental errors. A closer agreement is obtained with the mixture of habits. Simulated high resolution brightness temperatures based on retrieved cloud parameters (optical depths and effective dimensions) are compared with measured values in all the atmospheric windows covered by the NAST-I sensor. The agreement obtained in the 800–980 cm − 1 interval is generally better for the mixture of habits, but solid columns produce smaller residuals in the 2000–2150 and 2400–2600 cm − 1 spectral intervals. Uncertainties related to the surface properties (i.e. skin temperature) are recognized to be the main sources of error in the infrared retrieval of cloud properties and affect the comparison between forward simulations and NAST-I data in all the infrared window bands not used for the inverse problem.