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NASA NTRS1985

Spaceborne lidar system for measurements of atmospheric water vapor and aerosols

The inclusion of a differential absorption lidar (DIAL) system as part of the NASA Earth Observing System (EOS) is proposed. Functioning at 720 nm, the DIAL could provide atmospheric water vapor profiles in the troposphere and stratosphere, and provide data for characterizing the physical properties of clouds. The use of frequency doubling of the laser could also open a window on the 355 nm region, and thereby molecular density and temperature profiles. The date would be of use in studies of the global hydrological cycle, the global radiation balance, climate, meteorology, and atmospheric structure and transport phenomena.

Browell, E. V.↗

NASA NTRS2023

Potomac River Basin Water Resources: Assessing Water Quality and Quantity in the National Capital Region Using NASA Earth Observations

The Potomac River Basin (PRB) is responsible for providing drinking water to over 5 million residents and plays a significant role in the health of the Chesapeake Bay. Therefore, it is important to understand the relationship between water quality, landcover, and the hydrological cycle within the PRB. The National Park Service (NPS) has monitored 37 streams within the National Park Units in Maryland, Virginia, West Virginia and Washington, D.C. This project aimed to help the NPS better understand trends in water quality to supplement their ability to monitor changes in the National Capital Region Network (NCRN). Google Earth Engine, ArcGIS Pro, R, and Python were used for data retrieval, visualization, and analysis. Earth observations included Landsat 5 TM and Landsat 8 OLI/TIRS imagery. Ancillary data included the USDA Cropland Data Layer, Climate Hazards Group InfraRed Precipitation with Station Data (CHIRPS), and soil moisture data from the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System (FLDAS). We compared Land use/land cover (LULC), Normalized Difference Vegetation Index (NDVI), precipitation and soil moisture data to water quality data provided by the NPS at a watershed level. LULC change maps were also generated for the PRB between 2008 and 2022. We found significant correlations between precipitation, soil moisture, NDVI, and water quality. Correlations were found between certain land use types and water quality metrics, but findings varied greatly between watersheds. These insights emphasize the imperative of strategic watershed management in preserving the integrity of key aquatic systems.

Landsat↗

NASA NTRS2021

Informing Improvements in Freeze/Thaw State Classification Using Subpixel Temperature

Freeze/thaw (FT) processes at the earth’s surface can have a considerable effect on global carbon, energy, and hydrologic cycles. Therefore, an accurate representation of FT is valuable to adequately monitor and model these processes. In this study, we assess the relationship between satellite-based FT products and modeled surface and soil temperatures over North America. In addition, hourly land surface temperature (LST) from the Geostationary Operational Environmental Satellite (GOES) system is also compared to FT classifications. Utilizing the higher spatial resolution temperatures (5 km), we assess subgrid-scale variability and its relationship to coarser microwave FT classifications (>25 km). We also examine product agreement and subpixel characteristics across the land cover, climate, and topography. FT classifications are shown to vary widely depending on these variables, leading to an ambiguous definition of frozen and thawed states. Our results suggest that current products can characterize FT transitions with consistent subfreezing surface characteristics in far northern regions (>50 °N). However, uncertainty associated with FT classifications is shown to increase considerably as latitude decreases. Our results also suggest that fractional FT products, utilizing data inputs, such as LST, would provide a considerable improvement in mountainous regions with high intergrid cell heterogeneity, in regions characterized by ephemeral FT events (i.e., regions <40 °N), as well as during freeze and thaw onset periods. This study also provides insight to improving the representation of surface FT state by providing a clearer definition of the subpixel scale temperature characteristics that govern existing frozen classifications.

Earth observing systems↗

NASA NTRS2005

[Multi-Scale Convergence of Cold-Land Process Representation in Land-Surface Models, Microwave Remote Sensing, and Field Observations]

The cryosphere is a major component of the hydrosphere and interacts significantly with the global climate system, the geosphere, and the biosphere. Measurement of the amount of water stored in the snow pack and forecasting the rate of melt are thus essential for managing water supply and flood control systems. Snow hydrologists are confronted with the dual problems of estimating both the quantity of water held by seasonal snow packs and time of snow melt. Monitoring these snow parameters is essential for one of the objectives of the Earth Science Enterprise-understanding of the global hydrologic cycle. Measuring spatially distributed snow properties, such as snow water equivalence (SWE) and wetness, from space is a key component for improvement of our understanding of coupled atmosphere-surface processes. Through the GWEC project, we have significantly advanced our understandings and improved modeling capabilities of the microwave signatures in response to snow and underground properties.

Shi, Jiancheng↗

NASA NTRSDate not supplied

An Update on the Hydrological Land Surface Data and Services at NASA GES DISC

"The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is one of twelve NASA Earth Observing System data centers that document, process, archive and distribute data from Earth science missions and related projects. The GES DISC hosts many hydrological land surface data products including North American Land Data Assimilation System (NLDAS), Global Land Data Assimilation System (GLDAS), the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System (FLDAS), and assimilated-Gravity Recovery and Climate Experiment (GRACE). The Land Surface Model (LSM) products contain model output, including heat fluxes, rain, snow, soil temperature, soil moisture and runoff; and observational forcing data, including surface pressure, temperature, precipitation, downward shortwave and longwave radiation, humidity, and wind. The temporal resolution of the hydrology data at the GES DISC ranges from hourly to monthly and the spatial resolution 0.1 degree to 1.0 degree. The variability of Earth’s water and energy cycles can be characterized with these spatially and temporally consistent, and quality controlled hydrological land surface data. These data could support ongoing modeling activities, and help improve our understanding of land-surface-atmosphere interactions and their impact on climate. Over the years, new data is added, and older data is reprocessed and updated. This presentation provides a summary table of the hydrological data and discusses recent updates to the data and data services at the GES DISC. New data products include (1) GRACE Global Version 3.0 drought indicators and (2) FLDAS monthly global and Central Asia daily data. Reprocessed and updated products include (1) NLDAS Version 2.0 and (2) GRACE United States Version 4.0 drought indicators. Lastly, this presentation will discuss the opportunities for accessing some of our hydrology data from the cloud. As the hydrology land surface data is moved to the cloud, users can expect faster service for longer time series, notably the hydrology data rods time series service."

Ashley Heath↗

NASA NTRS1990

Definition and preliminary design of the Laser Atmospheric Wind Sounder (LAWS) phase 1. Volume 2

The steps and engineering trades and analyses used in establishing the initial requirements and in developing a concept and configuration for the laser atmospheric wind sounder (LAWS) instrument. A summary of the performance anticipated from the baseline configuration, and a bibliography are presented. LAWS, which is a facility instrument of the Earth observing system (EOS), is the culmination of over 20 years of effort in the field of laser Doppler wind sensing and will be the first instrument to fly in space capable of providing global-scale tropospheric wind profiles at high spatial resolutions. Global-scale wind profiles are necessary for: (1) more accurate diagnosis of large-scale circulation and climate dynamics; (2) improved numerical weather prediction; (3) improved understanding of mesoscale systems; and (4) improved understanding of global biogeochemical and hydrologic cycles. The objective of phase 1 was to define and perform a preliminary design for the LAWS instrument. The definition phase consisted of identifying realistic concepts for LAWS and analyzing them in sufficient detail to be able to choose the most promising one for the LAWS instrument. Systems and subsystems configurations were then developed for the chosen concept. The concept and subsequent configuration were to be compatible with two prospective platforms: the Japanese polar orbiting platform (JPOP) and as an attached payload on the Space Station Freedom. After a thorough and objective concept selection process, a heterodyne detection Doppler lidar using a CO2 laser transmitter operating a 9.1 micron over a 2.1 micron solid state system was chosen. A configuration for LAWS that meets the performance requirements was designed at the conclusion of phase 1.

Source record↗

NASA NTRS2002

Project to Interface Climate Modeling on Global and Regional Scales with Earth Observing (EOS) Observations

This ten-year NASA IDS project began in 1990. Its initial work plan adopted the NASA provided timeline that data would become available for new Earth Observing System (EOS) platforms beginning in 1995. Over its first phase, it was based at NCAR, which had submitted the original proposal and involved activities of a substantial number of co-investigators at NCAR who engaged in research over several areas related to the observations expected to be received from the EOS platforms. Their focus was the theme of use of EOS data for improving climate models for projecting global change. From the climate system viewpoint, the IDS addressed land, clouds-hydrological cycle, radiative fluxes and especially aerosol impacts, ocean and sea-ice, and stratosphere. Other research addressed issues of data assimilation, diagnostic analyses, and data set development from current satellite systems, especially use of SAR data for climate models.

Dickinson, Robert E.↗

NASA NTRS1990

Definition and Preliminary Design of the Laser Atmospheric Wind Sounder (LAWS) Phase 1. Volume 1: Executive Summary

The laser atmospheric wind sounder (LAWS) is a facility instrument of the Earth Observing System (EOS) and is the culmination of over 20 years of effort in the field of laser Doppler wind sensing. LAWS will by the first instrument to fly in space with the capability of providing global-scale tropospheric wind profiles at high spatial resolutions. Global-scale wind profiles are necessary for: (1) more accurate diagnostics of large-scale circulation and climate dynamics; (2) improved numerical weather prediction; (3) improved understanding of mesoscale systems; (4) improved understanding of global biogeochemical and hydrologic cycles. The objective of phase 1 of the LAWS study was to evaluate competing concepts and develop a baseline configuration for the LAWS instrument. The first phase of the study consisted of identifying realistic concepts for LAWS and analyzing them in sufficient detail to be able to choose the most promising one for the LAWS application. System configurations were then developed for the chosen concept. The concept and subsequent configuration were to be compatible with two prospective platforms: the Japanese polar orbiting platform (JPOP) and the Space Station Freedom (as an attached payload). After an objective and comprehensive concept selection process, a heterodyne detection Doppler lidar using a CO2 laser transmitter operating at 9.1 microns over a 2.1 micron system with a solid state laser was chosen. The CO2 lidar concept was then analyzed in detail to arrive at a configuration for the instrument and its major subsystems. A configuration for LAWS was arrived at which meets the performance requirements, and this design is presented.

Source record↗

NASA NTRS2006

Introduction to MODIS Cloud Products

The Earth's radiative energy balance and hydrological cycle are fundamentally coupled with the distribution and properties of clouds. Therefore, the ability to remotely infer cloud properties and their variation in space and time is crucial for establishing climatologies as a reference for validation of present-day climate models and in assessing future climate change. Remote cloud observations also provide data sets useful for testing and improving cloud model physics, and for assimilation into numerical weather prediction models. The MODerate Resolution Imaging Spectroradiometer (MODIS) imagers on the Terra and Aqua Earth Observing System (EOS) platforms provide the capability for globally retrieving these properties using passive solar reflectance and infrared techniques. In addition to providing measurements similar to those offered on a suite of historical operational weather platforms such as the Advanced Very High Resolution Radiometer (AVHRR), the High-resolution Infrared Radiation Sounder (HIRS), and the Geostationary Operational Environmental Satellite (GOES), MODIS provides additional spectral and/or spatial resolution in key atmospheric bands, along with on-board calibration, to expand the capability for global cloud property retrievals. The core MODIS operational cloud products include cloud top pressure, thermodynamic phase, optical thickness, particle size, and water path, and are derived globally at spatial resolutions of either 1- or 5-km (referred to as Level-2 or pixel-level products). In addition, the MODIS atmosphere team (collectively providing cloud, aerosol, and clear sky products) produces a combined gridded product (referred to as Level-3) aggregated to a 1 equal-angle grid, available for daily, eight-day, and monthly time periods. The wealth of information available from these products provides critical information for climate studies as well as the continuation and improved understanding of existing satellite-based cloud climatologies derived from heritage instruments. This chapter provides an overview of the MODIS Level-2 and -3 operational cloud products.

Baum, Bryan A.↗

NASA NTRS2006

Precipitation Measurements from Space: Why Do We Need Them?

Water is fundamental to the life on Earth and its phase transition between the gaseous, liquid, and solid states dominates the behavior of the weather/climate/ecological system. Precipitation, which converts atmospheric water vapor into rain and snow, is central to the global water cycle. It regulates the global energy balance through interactions with clouds and water vapor (the primary greenhouse gas), and also shapes global winds and dynamic transport through latent heat release. Surface precipitation affects soil moisture, ocean salinity, and land hydrology, thus linking fast atmospheric processes to the slower components of the climate system. Precipitation is also the primary source of freshwater in the world, which is facing an emerging freshwater crisis in many regions. Accurate and timely knowledge of global precipitation is essential for understanding the behavior of the global water cycle, improving freshwater management, and advancing predictive capabilities of high-impact weather events such as hurricanes, floods, droughts, and landslides. With limited rainfall networks on land and the impracticality of making extensive rainfall measurements over oceans, a comprehensive description of the space and time variability of global precipitation can only be achieved from the vantage point of space. This presentation will examine current capabilities in space-borne rainfall measurements, highlight scientific and practical benefits derived from these observations to date, and provide an overview of the multi-national Global Precipitation Measurement (GPM) Mission scheduled to be launched in the early next decade.

Hou, Arthur Y.↗

NASA NTRS2007

Precipitation Measurements from Space: The Global Precipitation Measurement Mission

Hou, Arthur Y.↗

NASA NTRS1988

LAWS (Laser Atmospheric Wind Sounder) earth observing system

Wind profiles can be measured from space using current technology. These wind profiles are essential for answering many of the interdisciplinary scientific questions to be addressed by EOS, the Earth Observing System. This report provides guidance for the development of a spaceborne wind sounder, the Laser Atmospheric Wind Sounder (LAWS), discussing the current state of the technology and reviewing the scientific rationale for the instrument. Whether obtained globally from the EOS polar platform or in the tropics and subtropics from the Space Station, wind profiles from space will provide essential information for advancing the skill of numerical weather prediction, furthering knowledge of large-scale atmospheric circulation and climate dynamics, and improving understanding of the global biogeochemical and hydrologic cycles. The LAWS Instrument Panel recommends that it be given high priority for new instrument development because of the pressing scientific need and the availability of the necessary technology. LAWS is to measure wind profiles with an accuracy of a few meters per second and to sample at intervals of 100 km horizontally for layers km thick.

Source record↗

NASA NTRS1988

Doppler lidar wind measurements on the EOS - LAWS

This paper discusses the efforts currently underway to prepare for the deployment of the Laser Atmospheric Wind Sounder (LAWS) instrument on an Earth Observing System (EOS) polar orbiter and on the Space Station. Attention is given to the measurement techiques, which include ground-based and airborne measurements in the atmosphere, and to the scientific and the technical issues being addressed. Global wind profiles obtained with the LAWS will effect dramatic improvement in numerical weather prediction and will be useful in determining the midtroposphere steering currents that are important in hurricane track forecasts. The global wind data will also provide information on large-scale atmospheric circulation and climate dynamics and on biogeochemical and hydrologic cycles.

Fitzjarrald, Daniel E.↗

NASA NTRS2001

Tropical Rainfall Measuring Mission: Monitoring the Global Tropics for 3 Years and Beyond

The Tropical Rainfall Measuring Mission (TRMM) was launched in November 1997 as a joint U.S.-Japanese mission to advance understanding of the global energy and water cycle by providing distributions of rainfall and latent heating over the global tropics. As a part of NASA's Earth System Enterprise, TRMM seeks to understand the mechanisms through which changes in tropical rainfall influence global circulation. Additionally, a goal is to improve the ability to model these processes in order to predict global circulations and rainfall variability at monthly and longer time scales. Such understanding has implications for assessing climate processes related to El Nino/La Nina and Global Warming. TRMM has also provided unexpected and exciting new knowledge and applications in areas related to hurricane monitoring, lightning, pollution, hydrology, and other areas. This CD-ROM includes a self-contained PowerPoint presentation that provides an overview of TRMM and significant science results; a set of data movies or animation; and listings of current TRMM-related publications in the literature.

Shepherd, Marshall↗

NASA NTRS2011

Radiative Energetics of Mineral Dust Aerosols from Ground-Based Measurements

Airborne dust aerosols worldwide contribute a significant part to air quality problems and, to some extent, regional climatic issues (e.g., radiative forcing, hydrological cycle, and primary biological productivity in oceans). Evaluating the direct solar radiative effect of dust aerosols is relatively straightforward due in part to the relatively large SIN ratio in broadband irradiance measurements. The longwave (LW) impact, on the other hand, is rather difficult to ascertain since the measured dust signal level (approx.10 W/sq m) is on the same order as the instrumental uncertainties. Although the magnitude of the LW impact is much smaller than that of the shortwave (SW), it can still have a noticeable influence on the energy distribution of Earth-atmosphere system, particularly due to the strong light-absorptive properties commonly found in many terrestrial minerals. The current effort is part of an ongoing research study to perform a global assessment of dust direct aerosol radiative effects (DARE) during major field deployments of key dust source regions worldwide. In this work we present results stemming from two previous field deployments: the 2006 NASA African Monsoon Multidisciplinary Activities and the 2008 Asian Monsoon Years, both utilizing NASA Goddard's mobile ground-based facility. The former study focused on transported Saharan dust at Sal (16.73degN, 22.93degW), Cape Verde along the west coast of Africa while the latter focused on Asian dust at Zhangye (39.082degN, 100.276degE), China near the source between the Taklimakan and Gobi deserts. Due to the compelling variability in spatial and temporal scale of dust properties during field experiments, a deterministic I-D radiative transfer model constrained by local measurements (i.e., spectral photometry/interferometry and lidar for physical/microphysical, mineralogy, and single-scattering properties) is employed to evaluate dust's local instantaneous SW/LW DARE both at the surface and at the top of the atmosphere along with heating rate profiles for cloud-free atmospheres. In both dust cases the efficiency in the L W DARE is investigated and its significance is compared relative to that of diurnally SW.

Tsay, Si-Chee↗

NASA NTRS2004

A Cloud Hydrology and Albedo Synthesis Mission (CHASM)

This slide presentation reviews the Cloud Hydrology and Albedo Synthesis Mission (CHASM). The interaction of clouds with radiation and the hydrological cycle represents a huge uncertainty in our understanding of climate science and the modeling of climate system feedbacks. Despite the recognized need for a unified treatment of cloud processes, the present global average values of remotely sensed cloud liquid water and theoretically accepted values used for cloud physics and precipitation modeling differ by an order of magnitude. This is due in part to sampling and saturation effects, as well as to threedimensional cloud structure effects. In recent work with the Multiangle Imaging SpectroRadiometer (MISR) on Terra, we have gained new insights as to how the remote sensing approach could be significantly improved using a new instrument that combines passive optical (visible and near infrared) and microwave measurements, both as pushbroom scanners with multiple viewing angles, to the degree that measurements of liquid water path over deep convective clouds over land also become possible. This instrument would also have the ability of measuring height-resolved cloud-tracked winds using a hyper stereo retrieval technique. Deployment into a precessing low earth orbit would be optimal for measuring diurnal cloud activity. We have explored an instrument design concept for this that looks promising if we can establish partnerships that provide launch and bus capabilities.

hydrology↗

NASA NTRS2004

Evaluation of the AMSR-E Data Calibration Over Land

Land observations by the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), particularly of soil and vegetation moisture changes, have numerous applications in hydrology, ecology and climate. Quantitative retrieval of soil and vegetation parameters relies on accurate calibration of the brightness temperature measurements. Analyses of the spectral and polarization characteristics of early versions of the AMSR-E data revealed significant calibration biases over land at 6.9 GHz. The biases were estimated and removed in the current archived version of the data Radiofrequency interference (RFI) observed at 6.9 GHz is more difficult to quanti@ however. A calibration analysis of AMSR-E data over land is presented in this paper for a complete annual cycle from June 2002 through September 2003. The analysis indicates the general high quality of the data for land applications (except for RFI), and illustrates seasonal trends of the data for different land surface types and regions.

Njoku, E.↗

NASA NTRS1994

Climate Change on Mars

Today, Mars is cold and dry. With a 7 mbar mean surface pressure, its thin predominantly CO2 atmosphere is not capable of raising global mean surface temperatures significantly above its 217K effective radiating temperature, and the amount of water vapor in the atmosphere is equivalent to a global ocean only 10 microns deep. Has Mars always been in such a deep freeze? There are several lines of evidence that suggest it has not. First, there are the valley networks which are found throughout the heavily cratered terrains. These features are old (3.8 Gyr) and appear to require liquid water to form. A warm climate early in Mars' history has often been invoked to explain them, but the precise conditions required to achieve this have yet to be determined. Second, some of the features seen in orbiter images of the surface have been interpreted in terms of glacial activity associated with an active hydrological cycle some several billion years ago. This interpretation is controversial as it requires the release of enormous quantities of ground water and enough greenhouse warming to raise temperatures to the melting point. Finally, there are the layered terrains that characterize both polar regions. These terrains are geologically young (10 Myr) and are believed to have formed by the slow and steady deposition of dust and water ice from the atmosphere. The individual layers result from the modulation of the deposition rate which is driven by changes in Mars' orbital parameters. The ongoing research into each of these areas of Martian climate change will be reviewed, and similarities to the Earth's climate system will be noted.

Haberle, R. M.↗