Progress in developing GeoSTAR: a microwave sounder for GOES-R

A microwave radiometer onboard a geostationary satellite can provide for the continuous atmospheric sounding of rapidly evolving convective events even in the presence of clouds, which has aroused great research interest in recent decades. To approach the problem of high-spatial resolution and large-size antennas, three promising geostationary microwave (GEO-MW) solutions—geostationary microwave radiometer (GMR) with a 5 m real aperture antenna, geostationary synthetic thinned aperture radiometer (GeoSTAR) with a Y-shaped synthetic aperture array, and geostationary interferometric microwave sounder (GIMS) with a rotating circular synthetic aperture array—have been proposed. To compare the potential impact of assimilating the three GEO-MW sounders to typhoon prediction, observing system simulation experiments (OSSEs) with the simulated 50–60 GHz observing brightness temperature data were conducted using the mesoscale numerical model Weather Research and Forecasting (WRF) and WRF Date Assimilation-Four dimensional variational (WRFDA-4Dvar) assimilation system for Typhoons Hagibis and Bualoi which occurred in 2019. The results show that the assimilation of the three GEO-MW instruments with 4 channels of data at 50–60 GHz could lead to general positive impacts in this study. Compared with the control experiment, for the two cases of Bualoi and Hagibis, GMR improves the average 72 h typhoon track forecast accuracy by 24% and 43%, GeoSTAR by 33% and 50%, and GIMS by 10% and 29%, respectively. Overall, the three GEO-MW instruments show considerable promise in atmospheric sounding and data assimilation. The difference among these positive impacts seems to depend on the observation error of the three potential instruments. GeoSTAR is slightly better than the other two GEO-MW sounders, which may be because it has the smallest observation error of the 4 assimilation channels. Generally, this study illustrates that the performance of these three GEO-MW sounders is potentially adequate to support assimilation into numerical weather prediction models for typhoon prediction.

Preliminary details of a 2-D synthetic aperture radiometer prototype operating from 50 to 55 GHz will be presented. The laboratory prototype is being developed to demonstrate the technologies and system design needed to do millimeter-wave atmospheric soundings with high spatial resolution from Geostationary orbit. The concept is to deploy a large thinned aperture Y-array on a geostationary satellite, and to use aperture synthesis to obtain images of the Earth without the need for a large mechanically scanned antenna. The laboratory prototype consists of a Y-array of 24 horn antennas, MMIC receivers, and a digital cross-correlation subsystem

The National Oceanic and Atmospheric Administration (NOAA) have been flying microwave sounders since 1975 on Polar Operational Environmental Satellites (POES). Microwave observations have made significant contributions to the understanding of the atmosphere and earth surface. This has helped in improving weather and storm tracking forecasts. However, NOAA's Geostationary Operational Environmental Satellites (GOES) have microwave requirements that can not be met due to the unavailability of proven technologies. Several studies of a Geostationary Microwave Sounder (GMS) have been conducted. Among those, are the Geostationary Microwave Sounder (GEM) that uses a mechanically steered solid dish antenna and the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) that utilizes a sparse aperture array. Both designs take advantage of the latest developments in sensor technology. NASA/Jet Propulsion Lab (JPL) has recently successfully built and tested a prototype ground-based GeoSTAR at 50 GHz frequency with promising test results. Current GOES IR Sounders are limited to cloud top observations. Therefore, a sounding suite of IR and Microwave should be able to provide observations under clear as well as cloudy conditions all the time. This paper presents the results of the Geostationary Microwave Sounder studies, user requirements, frequencies, technologies, limitations, and implementation strategies.

There are several microwave instruments in low Earth orbit (LEO) that are used for atmospheric temperature and humidity sounding by themselves and in conjunction with companion IR sounders. These instruments have achieved a certain degree of maturity and are undergoing a redesign to minimize their size, mass, and power requirements from the previous generation instruments. An example of these instruments is the AMSU-A series, now flying on POES and Aqua spacecraft, with the IR sounders HIRS3 and AIRS respectively. These older microwave instruments are going to be replaced by the ATMS instruments that will fly on NPP and NPOESS satellites with the CrIS IR sounder. A number of enabling technologies acquired from the ATMS instrument hardware design and data processing are directly applicable to performing similar microwave sounding on a geostationary platform. Because these technologies are already in place, they are readily available for the development of a geostationary orbit (GEO) microwave instrument, thereby avoiding costly technology development and minimizing the risk of not achieving the scientific requirements. In fact, the MMIC microwave components that were developed by ATMS for size and volume reduction are directly applicable to a GEO microwave sounder. The benefits of microwave sounders are well known. They penetrate non-precipitating cloud cover and allow for accurate soundings obtained with a collocated high spectral resolution IR sounder in up to 80% cloud cover. The key advantages of a microwave instrument in GEO will be its ability to provide high temporal resolution and uniform spatial resolution, and it will expand the utility of a collocated advanced IR sounder to cases in which partial cloud cover exists. A footprint in the order of 100 km by 100 km resolution with hemispherical coverage within one hour can be easily achieved for sounding channels in the 50 to 57 GHz range. A GEO microwave sounder will also allow mesoscale sampling of select regions.

GeoSTAR is a new microwave atmospheric sounder under development, with capabilities similar to sensors now operating on low Earth orbiting weather satellites. GeoSTAR is intended for deployment in geostationary orbit - where it complements future infrared sounders and enables all-weather temperature and humidity soundings and rain mapping. The required spatial resolution of 50 km at 50 GHz dictates an aperture of 4 meters or more, which is difficult to achieve with a real aperture system. GeoSTAR is instead based on a synthetic aperture imaging approach. Among the advantages of such a system are that there are no moving parts, and the size of the aperture is easily expandable to meet future needs. A ground based prototype of GeoSTAR is currently under development in an effort led by the Jet Propulsion Laboratory. We describe the measurement and calibration approach, system design, and selected technology elements.

GipsyX/RTGx is the Jet Propulsion Laboratory’s (JPL) next generation software package for positioning, navigation, timing, and Earth science using measurements from three geodetic techniques: Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS); with Very Long Baseline Interferometry (VLBI) under development. The software facilitates combined estimation of geodetic and geophysical parameters using a Kalman filter approach on real or simulated data in both post-processing and in real-time. The estimated parameters include station coordinates and velocities, satellite orbits and clocks, Earth orientation, ionospheric and tropospheric delays. The software is also capable of full realization of a dynamic terrestrial reference through analysis and combination of time series of ground station coordinates.Applying lessons learned from its predecessors, GIPSY-OASIS and Real Time GIPSY (RTG), GipsyX/RTGx was re-designed from the ground up to offer improved precision, accuracy, usability, and operational flexibility. We present some key aspects of its new architecture, and describe some of its major applications, including Real-time orbit determination and ephemeris predictions in the U.S. Air Force Next Generation GPS Operational Control Segment (OCX), as well as in JPL’s Global Differential GPS (GDGPS) System, supporting User Range Error (URE) of <5 cm RMS; precision post-processing GNSS orbit determination, including JPL’s contributions to the International GNSS Service (IGS) with URE in the 2 cm RMS range; Precise point positioning (PPP) with ambiguity resolution, both statically and kinematically, for geodetic applications with 2 mm horizontal, and 6.5 mm vertical repeatability for static positioning; Operational orbit and clock determination for Low Earth Orbiting (LEO) satellites, such as NASA’s Gravity Recovery and Climate Experiment (GRACE) mission with GRACE relative clock alignment at the 20 ps level; calibration of radio occultation data from LEO satellites for weather forecasting and climate studies; Satellite Laser Ranging (SLR) to GNSS and LEO satellites, DORIS-based and multi-technique orbit determination for LEO; production of terrestrial reference frames and Earth rotation parameters in support of JPL’s contribution to the International Terrestrial Reference Frame (ITRF).

SUMMARY As the main contributor to global sea-level rise, the Greenland Ice Sheet (GrIS) has undergone significant mass change over the last two decades. The satellite mission of GRACE (Gravity Recovery And Climate Experiment) and its follow-on mission (GRACE-FO) provide accurate observations but low-spatial resolution. In contrast, satellite altimetry provides observations at a high-spatial resolution but with large uncertainties, limiting the understanding of glacier-scale mass change. To derive accurate and high-spatial resolution mass change estimates from GRACE/GRACE-FO observations, we present a novel constraint mascon method in which the regularization matrix is constructed with the signal variances from satellite altimetry. Based on the proposed method, we derive a series of high-resolution (25 km × 25 km) monthly mascon solutions from 2002 April to September. The glacier-scale estimates from the input–output method agree better with those from our mascon solutions than those from the global mascons of CSR (Center for Space Research, the University of Texas), JPL (Jet Propulsion Laboratory), and GSFC (Goddard Space Flight Center), with a higher linear regression coefficient of 0.71. Benefitting from the greatly improved spatial resolution, our estimates provide the first accurate monthly glacier-scale mass change estimates from GRACE/GRACE-FO observations over the GrIS, to our knowledge. The results show that 20 of the 260 glaciers contributed to more than 42 per cent of the ice loss in the GrIS from 2002 to 2022. Most strikingly, the mass loss of Jakobshavn Isbrae was the most significant at –18.7 ± 0.05 Gt yr−1, accounting for 7.4 per cent of the total in the GrIS during the study period. Furthermore, we find that the SMB (surface mass balance) and ice-dynamics-related mass changes contribute nearly equally to the observed mass changes, but the corresponding spatiotemporal characteristics differ. SMB contributed the most to the mass change in 2019, while ice dynamics played the most dominant role in 2018. Moreover, the SMB effect is widespread, and ice-dynamics-related mass loss is mainly concentrated in five small areas.

High spatiotemporal resolution of terrestrial total water storage plays a key role in assessing trends and availability of water resources. This study presents a two-step method for downscaling GRACE-derived total water storage anomaly (GRACE TWSA) from its original coarse spatiotemporal resolution (monthly, 3-degree spherical cap/~300 km) to a high resolution (daily, 5 km) through combining land surface model (LSM) simulated high spatiotemporal resolution terrestrial water storage anomaly (LSM TWSA). In the first step, an iterative adjustment method based on the self-calibration variance-component model (SCVCM) is used to spatially downscale the monthly GRACE TWSA to the high spatial resolution of the LSM TWSA. In the second step, the spatially downscaled monthly GRACE TWSA is further downscaled to the daily temporal resolution. By applying the method to downscale the coarse resolution GRACE TWSA from the Jet Propulsion Laboratory (JPL) mascon solution with the daily high spatial resolution (5 km) LSM TWSA from the Ecological Assimilation of Land and Climate Observations (EALCO) model, we evaluated the benefit and effectiveness of the proposed method. The results show that the proposed method is capable to downscale GRACE TWSA spatiotemporally with reduced uncertainty. The downscaled GRACE TWSA are also evaluated through in-situ groundwater monitoring well observations and the results show a certain level agreement between the estimated and observed trends.

Today most operational Earth observing satellites reside in low Earth orbits (LEO) at less than 1,000 km altitude, and in geostationary Earth orbits (GEO) at ~35,800 km altitude. These orbits have been the venues of choice for observations, albeit for very different reasons. LEO provides high spatial resolution with low temporal resolution while GEO provides for low spatial resolution, but high temporal resolution. NOAA utilizes both venues for their environmental satellites. The NOAA Polar-orbiting Operational Environmental Satellites (POES) reside in LEO Sun synchronous orbits at approximately 830 km in altitude, as do the Defense Meteorological Satellite Program (DMSP) satellites of the Department of Defense. In the near future the POES and DMSP satellites will be merged into a new satellite system referred to as the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The NOAA Geostationary Operational Environmental Satellite (GOES) system, as the name specifies, resides at the other preferred observational venue of GEO. The Jet Propulsion Laboratory (JPL), under contract to NOAA, has been studying the characteristics of medium Earth orbits (MEO), at altitudes between 1000 and 35,800 km, as an observation venue to answer the question as to whether MEO might capture the attributes of the two traditional venues. This on-going study initially focused on determining the optimal altitude for MEO observations, through numerous trade studies involving altitude, instrument complexity, coverage, radiation environment, data temporality, revisit time, data rates, downlink requirements and other parameters including cost and launch complexity. Once the optimal altitude of 10,400 km had been determined the study proceeded to explore single through multiple MEO satellite constellation performance capabilities using two instrument types, a visible through infrared (IR) imager and IR sounder as the satellites’ payload. The MEO performance capabilities were compared to comparable LEO and GEO satellite constellation capabilities. This portion of the study concluded that indeed for global coverage a constellation of satellites operating in the MEO venue could capture the attributes of those operating in the LEO and GEO venues. Three 8-satellite constellations configurations - Walker, ICO, and Equatorial-Polar (EP) - then were studied to develop more constellation coverage statistics including robustness to individual satellite failure. That study phase concluded that the EP constellation was superior to both the ICO and Walker configurations. The study is presently examining if, and to what extent, the equatorial portion of the EP constellation might provide substantive supplemental data to that collected by the NPOESS and GOES satellite constellations.

Photoacoustic imaging combines advantages of both ultrasound imaging and optical imaging to provide high ultrasonic resolution and high optical contrast in noninvasive medical images. A photoacoustic computer tomography （PCT） system with a focused digital phased array transducer is proposed. In particular each element of the transducer array has a thin cylindrical ultrasonic lens to select 2D image plane and suppress the out-of-plane signals to realize photoacoustic computed tomography. A fast full-view photoacoustic imaging system for visualizing tissue structures using a linear transducer array with combined scan, whies; detects photoacoustic signals by combined electronic and mechanical scanning. An improved limited-field filtered back projection algorithm with directivity factors was applied to reconstruct the optical absorption distribution and further improve the lateral resolution. In the experiment, the spatial resolution of this imaging system is determined as 0.2mm, and the slice resolution of Z axis is 1.5mm. Mechanical step scanning was performed, leading to a measurement time of 6.4 seconds per position, and a total scan duration of 150 seconds to obtain the two-dimensional photoacoustic image. High spatial resolution of 2D photoacoustic vascular image and quasi-3D photoacoustic CT for breast cancer imaging are achicned. The experimental results demonstrate that this method and imaging system can realize the high resolution photoacoustic tomography wtich can be applied to noninvasive detection of early breast cancer.

CH 4 is a potent greenhouse gas with a 100-year Global Warming Potential more than thirty times larger than CO 2 if carbon-climate feedbacks are considered.In urban areas such as Los Angeles, anthropogenic methane emissions are poorly characterized because of the large diversity of sources: landfills, sewage treatment plants, agriculture, leaks in the natural gas distribution system, cattle and dairy farms, thermogenic emissions from oil fields and seeps.The California Laboratory for Atmospheric Remote Sensing (CLARS), operated by the Jet Propulsion Laboratory, is a mountaintop facility overlooking most of the Los Angeles basin, equipped with JPL-built Fourier transform spectrometers for measurements of the slant column abundances of several greenhouse gases including methane with high spatial and temporal resolution.This presentation will cover several topics including the design features of the two FTS instruments, spectroscopic issues associated with the retrieval of slant column abundances, and uncertainty analysis.One FTS has been in continuous operation since 2011, providing sufficient data to identify several CH 4 emission hot spots in the LA basin.On October 23, 2015, a well pipe suffered a failure in a natural gas storage facility in Aliso Canyon, northwest of downtown Los Angeles resulting in a massive CH 4 plume transported by winds throughout the LA basin.The CLARS FTS captured the plume propagation throughout the 4-month duration of the leak.We will show how the emission ratio method may be employed to derive a lower bound to the CH 4 emission rate from the leaking well without the use of complex atmospheric transport models.The CLARS measurement system provides a small-scale example of the data that would be acquired by an imaging FTS on a geostationary space platform.

Arbitrary characteristics of optical interference have been realized, in our group, by Synthesis of Optical Coherence Function(SOCF) with electrical control and without mechanical scanning. Various applications for optical sensing have been developed by SOCF. Delta function like optical coherence function with higher spatial resolution and higher dynamic range have been achieved by using a broadband tunable super-structure-grating distributed Bragg reflector laser diode (SSG-DBRLD). This time, we improve driving circuit and frequency calibration of the SSG-DBR-LD to achieve a 5THz tunable band width. We apply the characteristics to distributed fiber optic force sensing using polarization maintaining fiber (PMF) as a sensing head. Its principle is polarization mode coupling by the force applied to the fiber. In the experiment, we improve the spatial resolution more than one digit compared with the previous data, and realize 20cm. This technique can be used as a nerve system for smart materials and structures.

A synthetic aperture radiometer is a new type of passive remote sensing instrument that can reach high spatial resolution. Restricted by antenna element size and operating wavelength, however, the system design is difficult at MMW band. In this paper, main technical parameters optimization of a synthetic aperture radiometer is discussed. Based on low-redundancy linear arrays, a millimeter wave synthetic aperture radiometric imaging scheme is presented. The simulation experimental results show that the system imaging effect depends on the synthetic aperture antenna pattern.

The majority of today's CubeSat fleet consists of Earth-orbiting missions that mostly use existing ground systems developed by universities because of availability, simplicity, and low-cost. The Interplanetary NanoSpacecraft Pathfinder In Relevant Environment (INSPIRE) mission is a revolutionary CubeSat mission that will launch a pair of CubeSats into deep space to study the feasibility of CubeSats beyond low-Earth orbit. This uncovers a new set of systems and software engineering challenges to the development of a robust and reliable ground system in a low-cost environment. In this paper, we discuss the approach to these challenges by using the Jet Propulsion Laboratory's (JPL) Advanced Multimission Operation System (AMMOS) Ground Data System (GDS) as well as the methodologies used to engineer the flight system to work with an existing ground system developed for large-scale missions. Specifically we will focus on the command and telemetry subsystem of AMMOS, the Multimission Data Processing and Control System. We conclude with a retrospective on the challenges encountered and a brief discussion on our efforts to provide AMMOS to support future deep space CubeSat missions.

Robotic missions beyond 2013 will likely be precursors to a manned habitat deployment on Mars. Such missions require robust control systems for long duration activities. Current single rover missions will evolve into deployment of multiple, heterogeneous cooperating robotic colonies. This paper describes the map-making memory and action selection mechanism of BISMARC (\underline{\rm B}iologically \underline{\rm I}nspired \underline{\rm S}ystem for \underline{\rm M}ap-based \underline{\rm A}utonomous \underline{\rm R}over \underline{\rm C}ontrol) that is currently under development at the Jet Propulsion Laboratory in Pasadena, CA (Huntsberger and Rose, i>Neutral Networks, 11(7/8):1497–1510). BISMARC is an integrated control system for long duration missions involving robots performing cooperative tasks.