High Spatial Resolution Soil Moisture Mapping Using an L-Band Lobe Differencing Correlation Radiometer on a Small Unmanned Aerial System (Suas)

An L-band Lobe Differencing Correlation Radiometer (LDCR) was designed, developed and demonstrated for high spatial resolution soil moisture mapping from a small unmanned aerial system (sUAS). A lightweight lobe-differencing antenna was designed as a 2x2 rectangular L-band microstrip array with effective use of styrofoam blocks for frequency tuning and mechanical stability. An optimal vertical separation distance was identified that minimizes mutual coupling and provides maximum main-to-back lobe ratio. A method of antenna frequency tuning using dielectric overlay material is presented to correct for the dielectric impact of the sUAS fuselage. The LDCR RF front end design and performance are detailed. The LDCR was calibrated using both pre-flight lab test data and in-flight data over a calm pond to determined its sensitivities and offset which are compared with analytical values. Radio frequency interference (RFI) from the sUAS platform was observed prior to platform integration prompting RFI mitigation to be performed upon integration of the radiometer into the platform. Flight tests of the LDCR on the Black Swift Technology's Tempest sUAS were performed at the Canton, Oklahoma Soilscape site in September 2015 and Irrigation Research Foundation (IRF) in Yuma Colorado in June 2016. Based on a soil vegetation radiative transfer (SVRT) model for the LDCR, the LDCR TA measurements observed on the sUAS sampling grid were mapped to estimated volumetric soil moisture (VSM) on a regular user-defined mapping grid. The estimator used a new full-domain linear minimum mean square error (LMMSE) VSM retrieval algorithm, along with LDCR infrared physical temperature TP measurements, Landsat-based vegetation water content (VWC) maps, and soil texture information. The LDCR error budget for this algorithm was developed. The initially retrieved VSM data are favorably compared with in-situ measured VSM data and irrigation records

Characterization of clouds and their radiative effects using ground-based instrumentation at a low-mountain site

The interaction of clouds with radiation and aerosols is the greatest source of uncertainty in future climate projections. Part of the reason is the limited amount of observations of clouds and hence the limited knowledge of cloud macro- and microphysical statistics in connection to their effects on the radiative budget and on the vertical redistribution of energy within the atmosphere. In 2007, the Atmospheric Radiation Measurement program�s (ARM) Mobile Facility (AMF) was operated for a nine-month period in the Murg Valley, Black Forest, Germany, in support of the Convective and Orographically-induced Precipitation Study (COPS). Based on the measurements of the AMF and COPS partner instrumentation, the present study aims at improving the data basis of cloud macro- and microphysical statistics and to assess the potential of the derived cloud properties to estimate the radiative effects of clouds. The synergy of various instruments is exploited to derive a data set of high quality thermodynamic and cloud property profiles with a temporal resolution of 30 s. While quality filters in the cloud microphysical retrieval techniques mostly affect the representativity of ice and mixed clouds in the data sample, water clouds are very well represented in the derived 364,850 atmospheric profiles. In total, clouds are present 72% of the time with multi-layer mixed phase (28.4%) and single-layer water clouds (11.3%) occurring most frequently. In order to evaluate the derived thermodynamic and cloud property profiles,radiative closure studies are performed with independent radiation measurements. In clear sky, average differences between calculated and observed surface fluxes are less than 2.1% and 3.6% for the shortwave and longwave, respectively. In cloudy situations, differences, in particular in the shortwave, are much larger, but most of these can be related to broken cloud situations. The cloud radiative effect (CRE), i.e. the difference of cloudy and clear-sky net fluxes, has been analyzed for the whole nine-month period. The largest surface (SFC) net CRE has been found for multi-layer water (-110 Wm-2) and mixed clouds (-116 Wm-2). The estimated uncertainties in the modeled SFC and top of atmopshere (TOA) net CRE are up to 39% and 26%, respectively. For overcast, single-layer water clouds, sensitivity studies reveal that the SW CRE uncertainty at the SFC and TOA is likewise determined by uncertainties in liquid water path (LWP) and effective radius, if the LWP is larger than 100 gm-2. For low LWP values, uncertainties in SFC and TOA shortwave CRE are dominated by the uncertainty in LWP. Uncertainties in CRE due to uncertainties in the shape of the liquid water content (LWC) profile are typically smaller by a factor of two compared to LWP uncertainties. For the difference between the cloudy and clear-sky net heating rates, i.e. the cloud radiative forcing (CRF), of water clouds, the LWP and its vertical distribution within the cloud boundaries are the most important factors. In order to increase the accuracy of LWC profiles and consequentially of the estimates of CRE and CRF, advanced LWC retrieval techniques, such as the Integrated Profiling Technique (IPT), are needed. The accuracy of a LWC profile retrieval using typical microwave radiometer brightness temperatures and/or cloud radar reflectivities is investigated for two realistic cloud profiles. The interplay of the errors of the a priori profile, measurements and forward model on the retrieved LWC error and on the information content of the measurements is analyzed in detail. It is shown that the inclusion of the microwave radiometer observations in the LWC retrieval increases the number of degrees of freedom, i.e. the independent pieces of information in the measurements, by about 1 compared to a retrieval using measuremets from the cloud radar alone. Assuming realistic measurement and forward model errors, it is further demonstrated, that the error in the retrieved LWC is 60% or larger, if no a priori information is available, and that a priori information is essential for a better accuracy. The results of the present work strongly suggest to improve the LWC a priori profile and the corresponding error estimates in the IPT. However, there are few observational datasets available to construct accurate a priori profiles of LWC, and thus more observational data are needed to improve the knowledge of the a priori profile and the corresponding error covariance matrix

The Telecommunications and Data Acquisition Report

Developments in space communications, radio navigation, radio science, ground-base radio astronomy, reports on the Deep Space Network (DSN) and its Ground Communications Facility (GCF), and applications of radio interferometry at microwave frequencies are discussed

Solar thermal heating and cooling. A bibliography with abstracts

This bibliographic series cites and abstracts the literature and technical papers on the heating and cooling of buildings with solar thermal energy. Over 650 citations are arranged in the following categories: space heating and cooling systems; space heating and cooling models; building energy conservation; architectural considerations, thermal load computations; thermal load measurements, domestic hot water, solar and atmospheric radiation, swimming pools; and economics

Deep space communication and navigation study. Volume 2 - Communication technology Final report

Alternative types of communication systems for deep space probes and extent of aid spacecraft can provide for deep space navigatio

Environmental Sciences Division: Summaries of research in FY 1996

This document describes the Fiscal Year 1996 activities and products of the Environmental Sciences Division, Office of Biological and Environmental Research, Office of Energy Research. The report is organized into four main sections. The introduction identifies the basic program structure, describes the programs of the Environmental Sciences Division, and provides the level of effort for each program area. The research areas and project descriptions section gives program contact information, and provides descriptions of individual research projects including: three-year funding history, research objective and approach used in each project, and results to date. Appendixes provide postal and e-mail addresses for principal investigators and define acronyms used in the text. The indexes provide indexes of principal investigators, research institutions, and keywords for easy reference. Research projects are related to climatic change and remedial action