Mathew R. Schwaller

A Ground Validation Network for the Global Precipitation Measurement Mission

Abstract A prototype Validation Network (VN) is currently operating as part of the Ground Validation System for NASA’s Global Precipitation Measurement (GPM) mission. The VN supports precipitation retrieval algorithm development in the GPM prelaunch era. Postlaunch, the VN will be used to validate GPM spacecraft instrument measurements and retrieved precipitation data products. The period of record for the VN prototype starts on 8 August 2006 and runs to the present day. The VN database includes spacecraft data from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and coincident ground radar (GR) data from operational meteorological networks in the United States, Australia, Korea, and the Kwajalein Atoll in the Marshall Islands. Satellite and ground radar data products are collected whenever the PR satellite track crosses within 200 km of a VN ground radar, and these data are stored permanently in the VN database. VN products are generated from coincident PR and GR observations when...

Prospects for satellite remote sensing of Adelie penguin rookeries

Abstract Future conservation efforts are expected to require population statistics for Southern Ocean species, including penguins. Preliminary laboratory spectral reflectance measurements are presented of penguin plumage plus some of the major components of the Antarctic environment. A sketch is presented of the prospects for employing remote sensing systems for monitoring penguin populations on a regional scale.

Global Precipitation Measurement Cold Season Precipitation Experiment (GCPEx): For Measurement Sake Let it Snow

AbstractAs a component of Earth’s hydrologic cycle, and especially at higher latitudes, falling snow creates snowpack accumulation that in turn provides a large proportion of the freshwater resources required by many communities throughout the world. To assess the relationships between remotely sensed snow measurements with in situ measurements, a winter field project, termed the Global Precipitation Measurement (GPM) Cold Season Precipitation Experiment (GCPEx), was carried out in the winter of 2011/12 in Ontario, Canada. Its goal was to provide information on the precipitation microphysics and processes associated with cold season precipitation to support GPM snowfall retrieval algorithms that make use of a dual-frequency precipitation radar and a passive microwave imager on board the GPM core satellite and radiometers on constellation member satellites. Multiparameter methods are required to be able to relate changes in the microphysical character of the snow to measureable parameters from which precip...

The changes in leaf reflectance of sugar maple (Acer saccharum Marsh) seedlings in response to heavy metal stress

Abstract The effects of heavy metal stress on leaf reflectance of sugar maple (Acer saccharum Marsh) seedlings were examined. Sugar maple seedlings treated with anomalous amounts of heavy metals in the rooting medium exhibited an increased leaf reflectance over the entire range of investigated wavelengths, from 475 to 1650 nm. These results conform to those of a previous investigation in the visible wavelengths from 475 to 660 nm, but tend to contradict the previous study in the near infrared wavelengths from 1000 to 1650 nm. The differences may possibly be due to different water regimes in the two investigations.

The Olympic Mountains Experiment (OLYMPEX)

OLYMPEX is a comprehensive field campaign to study how precipitation in Pacific storms is modified by passage over coastal mountains.

Salient features of the dual‐frequency, dual‐polarized, Doppler radar for remote sensing of precipitation

The global precipitation measurement (GPM) mission is an international satellite mission to obtain accurate observations of precipitation on a global scale every 3 h. Its (GPM) core satellite was launched on 27 February 2014 with two science instruments: the microwave imager and the dual-frequency precipitation radar. Ground validation is an integral part of the GPM mission where instruments are deployed to complement and correlate with spacecraft instruments. The dual-frequency, dual-polarization, Doppler radar (D3R) is a critical ground validation instrument that was developed for the GPM program. This paper describes the salient features of the D3R in the context of the GPM ground validation mission. The engineering and architectural overview of the radar is described, and observations from successful GPM ground validation field experiments are presented.

Scientific and engineering overview of the NASA Dual-Frequency Dual-Polarized Doppler Radar (D3R) system for GPM Ground Validation

As an integral part of Global Precipitation Measurement (GPM) mission, Ground Validation (GV) program proposes to establish an independent global cross-validation process to characterize errors and quantify uncertainties in the precipitation measurements of the GPM program. A ground-based Dual-Frequency Dual-Polarized Doppler Radar (D3R) that will provide measurements at the two broadly separated frequencies (Ku- and Ka-band) is currently being developed to enable GPM ground validation, enhance understanding of the microphysical interpretation of precipitation and facilitate improvement of retrieval algorithms. The first generation D3R design will comprise of two separate co-aligned single-frequency antenna units mounted on a common pedestal with dual-frequency dual-polarized solid-state transmitter. This paper describes the salient features of this radar, the system concept and its engineering design challenges.

Mapping the Abundance and Distribution of Adélie Penguins Using Landsat-7: First Steps towards an Integrated Multi-Sensor Pipeline for Tracking Populations at the Continental Scale

The last several years have seen an increased interest in the use of remote sensing to identify the location of penguin colonies in Antarctica, and the estimation of the abundance of breeding pairs contained therein. High-resolution (sub-meter) commercial satellite imagery (e.g., Worldview-1, Quickbird) is capable of colony detection and abundance estimation for both large and small colonies, and has already been used in a continental-scale survey of Adélie penguins. Medium-resolution Landsat imagery has been used successfully to detect the presence of breeding penguins, but has not been used previously for abundance estimation nor evaluated in terms of its minimum colony size detection threshold. We report on the first comprehensive analysis of the performance of these two methods for both detection and abundance estimation, identify the sensor-specific failure modes that can lead to both false positives and false negatives, and compare the abundance estimates of each method over multiple spatial scales. We find that errors of omission using Landsat imagery are low for colonies larger than ∼10,000 breeding pairs. Both high-resolution and Landsat imagery can be used to obtain unbiased estimates of abundance, and while Landsat-derived abundance estimates have high variance for individual breeding colonies relative to estimates derived from high-resolution imagery, this difference declines as the spatial domain of interest is increased. At the continental scale, abundance estimates using the two methods are roughly equivalent. Our comparison of these two methods represents a bridge between the more developed high-resolution imagery, which can be expensive to obtain, and the medium-resolution Landsat-7 record, which is freely available; this comparison of methodologies represents an essential step towards integration of these disparate sources of data for regional assessments of Adélie population abundance and distribution.

Observations of Storm Signatures by the Recently Modified Conical Scanning Millimeter-Wave Imaging Radiometer

The Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR) is an airborne total-power radiometer that, after the recent modification, measures radiation at the nine frequencies of 50.3, 52.8, 89 (dual-polarized), 165 (dual-polarized), 183.3 ± 1, 183.3 ± 3, and 183.3 ± 7 GHz. During the Mid-latitude Continental Convective Clouds Experiment of April 22-June 1, 2011, it is programmed to acquire radiometric measurements in both conical and cross-track scans nearly simultaneously. Its new capability of measuring scattering signatures from storm-associated hydrometeors in dual polarization at both 89 and 165 GHz is illustrated and reported in this paper. We find that, from all seven flights over stratiform rain and convective storms, the polarization index (PI), is small but definitively positive at both frequencies, and generally (89 GHz) ≤ PI(165 GHz). When brightness temperatures Tbps are ≥ 240 K, there is a significant correlation between PIand the brightness difference between the two frequencies (dTbp = Tbp(89) - Tbp(165) , where p is either vertical V or horizontal H polarization); linear regression between these two parameters gives positive slopes for all seven events, with 165-GHz slopes generally larger the 89-GHz ones. Observations from five special sensor microwave imager/sounder passes in near concurrence with the CoSMIR measurements are examined for the relation between PI(91.665 GHz) and dTbh (91.665 GHz-150 GHz). The regression slopes are again found to be positive, and their magnitudes show some correspondence to those of CoSMIR. The significance of these findings to improvement in the parameter retrievals of hydrometeors is briefly discussed.

Global Precipitation Measurement (GPM) Ground Validation (GV) Prototype in the Korean Peninsula

AbstractSince 2009, the Korea Meteorological Administration (KMA) has participated in ground validation (GV) projects through international partnerships within the framework of the Global Precipitation Measurement (GPM) Mission. The goal of this work is to assess the reliability of ground-based measurements in the Korean Peninsula as a means for validating precipitation products retrieved from satellite microwave sensors, with an emphasis on East Asian precipitation. KMA has a well-developed operational weather service infrastructure composed of meteorological radars, a dense rain gauge network, and automated weather stations. Measurements from these systems, including data from four ground-based radars (GRs), were combined with satellite data from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and used as a proxy for GPM GV over the Korean Peninsula. A time series of mean reflectivity differences (GR − PR) for stratiform-only and above-brightband-only data showed that the time-av...