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Papers by Sharmila Padmanabhan
The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) miss... more The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) mission is to demonstrate the capability of 6U-Class satellite constellations to perform repeat-pass radiometry to measure clouds and precipitation with high temporal resolution on a global basis. The TEMPEST mission concept is to improve understanding of clouds and precipitation by providing critical information on their time evolution in different climatic regimes. Measuring at five frequencies from 89 to 182 GHz, TEMPEST-D millimeter-wave radiometers are capable of penetrating into the cloud to observe changes as precipitation begins or ice accumulates inside the storm. The TEMPEST-D flight model radiometer instrument has been completed, passed functional testing, vibration testing and self-compatibility testing with the XB1 spacecraft bus. The next steps for the TEMPEST-D millimeter-wave radiometer are thermal vacuum testing and antenna pattern measurements. The complete TEMPEST-D flight...
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium
2017 IEEE Aerospace Conference
Sensors, Systems, and Next-Generation Satellites XXV
2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)
2019 URSI Asia-Pacific Radio Science Conference (AP-RASC)
IEEE Transactions on Geoscience and Remote Sensing
IEEE Transactions on Geoscience and Remote Sensing
![Research paper thumbnail of Modeling in Remote Sensing Technical Committee Activities [Technical Committees]](https://attachments.academia-assets.com/73195391/thumbnails/1.jpg)
](IEEE Geoscience and Remote Sensing Magazine
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
<p&amp... more <p>Passive microwave radiometer systems have provided both temperature and water vapor sounding of the Earth’s atmosphere for several decades, including MSU, AMSU, MHS, ATMS, etc.  Due to its ability to penetrate clouds, dust, and aerosols, among global datasets, microwave atmospheric sounding provides the most valuable quantitative contribution to weather prediction.  Long-term, well-calibrated sounding records can be indispensable for climate measurement and model initialization/validation.  Hence, passive microwave sounders are deployed on large, operational satellites and operated by NOAA, EUMETSAT and other similar national/international organizations.</p><p>In the past five years or so, advances in CubeSats and other small satellites have enabled highly affordable space technology, providing access to space to private industries, universities and smaller nations.  This provides a valuable opportunity for organizations such as NOAA and EUMETSAT to explore the added value of acquiring data from passive microwave sounders on small, low-cost spacecraft for relatively small investments, both for sensor and spacecraft acquisition and launch.  This provides the potential for deployment of constellations of low-Earth orbiting microwave sounders to provide much more frequent revisit times than are currently available.</p><p>For passive microwave sounding data to be valuable for weather prediction and climate monitoring, each sensor needs to be calibrated and validated to acceptable accuracy and stability.  In this context, the first CubeSat-based multi-frequency microwave sounder to provide global data over a substantial period is the Temporal Experiment for Storms and Tropical Systems Demonstration (TEMPEST-D) mission.  This mission was designed to demonstrate on-orbit capabilities of a new, five-frequency millimeter-wave radiometer to enable a complete TEMPEST mission using a closely-spaced train of eight 6U CubeSats with identical low-mass, low-power millimeter-wave sensors to sample rapid changes in convection and surrounding water vapor every 3-4 minutes for up to 30 minutes.  TEMPEST millimeter-wave radiometers scan across track and observe at five frequencies from 87 to 181 GHz, with spatial resolution ranging from 25 km to 13 km, respectively.</p><p>The TEMPEST-D satellite was launched on May 21, 2018 from NASA Wallops to the ISS and was successfully deployed on July 13, 2018, into a 400-km orbit at 51.6° inclination.  The TEMPEST-D sensor has been operating nearly continuously since its first light data on September 5, 2018.  With more than 16 months of operations to date, TEMPEST-D met all of its Level-1 mission objectives within the first 90 days of operations and has successfully achieved TRL 9 for both instrument and spacecraft systems. </p><p>Validation of observed TEMPEST-D brightness temperatures is performed by comparing to coincident observations by well-calibrated on-orbit instruments, including GPM/GMI and MHS on NOAA-19, MetOp-A and MetOp-B satellites. Absolute calibration accuracy is within 0.9 K for all except the…
Journal of Atmospheric and Oceanic Technology
The rapid development of miniaturized satellite instrument technology has created a new opportuni... more The rapid development of miniaturized satellite instrument technology has created a new opportunity to deploy constellations of passive microwave (PMW) radiometers to permit retrievals of the same Earth scene with very high temporal resolution to monitor cloud evolution and processes. In order for such a concept to be feasible, it must be shown that it is possible to distinguish actual changes in the atmospheric state from the variability induced by making observations at different Earth incidence angles (EIAs). To this end, we present a flexible and physical optimal estimation-based algorithm designed to retrieve profiles of atmospheric water vapor, cloud liquid water path, and cloud ice water path from cross-track PMW sounders. The algorithm is able to explicitly account for the dependence of forward model errors on EIA and atmospheric regime. When the algorithm is applied to data from the Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) Cub...
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
CubeSats and NanoSats for Remote Sensing, 2016
2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2016
2016 IEEE MTT-S International Microwave Symposium (IMS), 2016
2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2016
Igarss 2008 2008 Ieee International Geoscience and Remote Sensing Symposium, Jul 7, 2008
ABSTRACT Quantitative precipitation forecasting is currently limited by the paucity of observatio... more ABSTRACT Quantitative precipitation forecasting is currently limited by the paucity of observations of thermodynamic variables in the troposphere, including water vapor. Specifically, measurements of 3-D water vapor fields are needed at sub-meso-gamma scales in pre- storm conditions. This can be achieved using a network of remote sensors to retrieve the water vapor field with high spatial and temporal resolution. Such measurements may be used for assimilation into and validation of numerical weather prediction (NWP) models. Conventional measurements of water vapor density profiles are obtained using in-situ probes on-board weather balloons, including radiosondes. Remote sensing techniques to retrieve moisture profiles include ground-based networks receiving Global Navigation Satellite Systems (GNSS) signals, including GPS, and GPS receivers aboard the COSMIC satellite constellation for atmospheric occultation. These methods provide measurements with high vertical resolution but with coarse horizontal resolution. Differential Absorption Lidars (DIAL) can retrieve water vapor with comparable resolution to that of radiosonde observations. However, these lidars are expensive, and their operation is limited to clear-sky conditions due to the high opacity of clouds at optical wavelengths. Inversion of brightness temperatures measured by upward- looking, ground-based microwave radiometers allows the estimation of vertical profiles with high temporal resolution in both clear and cloudy conditions. However, assimilation of retrieved 3-D water vapor fields with improved spatial coverage into NWP models in pre-storm conditions has the potential for substantial impact on numerical weather prediction of convective storm activity. Measurements using a network of multi-frequency microwave radiometers can provide the necessary information to retrieve the 3-D distribution of water vapor in the troposphere.
ABSTRACT: WindSat, the first polarimetric microwave radiometer on orbit, and the NPOESS Conical M... more ABSTRACT: WindSat, the first polarimetric microwave radiometer on orbit, and the NPOESS Conical Microwave Imager/Sounder,
The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) miss... more The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) mission is to demonstrate the capability of 6U-Class satellite constellations to perform repeat-pass radiometry to measure clouds and precipitation with high temporal resolution on a global basis. The TEMPEST mission concept is to improve understanding of clouds and precipitation by providing critical information on their time evolution in different climatic regimes. Measuring at five frequencies from 89 to 182 GHz, TEMPEST-D millimeter-wave radiometers are capable of penetrating into the cloud to observe changes as precipitation begins or ice accumulates inside the storm. The TEMPEST-D flight model radiometer instrument has been completed, passed functional testing, vibration testing and self-compatibility testing with the XB1 spacecraft bus. The next steps for the TEMPEST-D millimeter-wave radiometer are thermal vacuum testing and antenna pattern measurements. The complete TEMPEST-D flight...
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium
2017 IEEE Aerospace Conference
Sensors, Systems, and Next-Generation Satellites XXV
2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)
2019 URSI Asia-Pacific Radio Science Conference (AP-RASC)
IEEE Transactions on Geoscience and Remote Sensing
IEEE Transactions on Geoscience and Remote Sensing
IEEE Geoscience and Remote Sensing Magazine
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
<p&amp... more <p>Passive microwave radiometer systems have provided both temperature and water vapor sounding of the Earth’s atmosphere for several decades, including MSU, AMSU, MHS, ATMS, etc.  Due to its ability to penetrate clouds, dust, and aerosols, among global datasets, microwave atmospheric sounding provides the most valuable quantitative contribution to weather prediction.  Long-term, well-calibrated sounding records can be indispensable for climate measurement and model initialization/validation.  Hence, passive microwave sounders are deployed on large, operational satellites and operated by NOAA, EUMETSAT and other similar national/international organizations.</p><p>In the past five years or so, advances in CubeSats and other small satellites have enabled highly affordable space technology, providing access to space to private industries, universities and smaller nations.  This provides a valuable opportunity for organizations such as NOAA and EUMETSAT to explore the added value of acquiring data from passive microwave sounders on small, low-cost spacecraft for relatively small investments, both for sensor and spacecraft acquisition and launch.  This provides the potential for deployment of constellations of low-Earth orbiting microwave sounders to provide much more frequent revisit times than are currently available.</p><p>For passive microwave sounding data to be valuable for weather prediction and climate monitoring, each sensor needs to be calibrated and validated to acceptable accuracy and stability.  In this context, the first CubeSat-based multi-frequency microwave sounder to provide global data over a substantial period is the Temporal Experiment for Storms and Tropical Systems Demonstration (TEMPEST-D) mission.  This mission was designed to demonstrate on-orbit capabilities of a new, five-frequency millimeter-wave radiometer to enable a complete TEMPEST mission using a closely-spaced train of eight 6U CubeSats with identical low-mass, low-power millimeter-wave sensors to sample rapid changes in convection and surrounding water vapor every 3-4 minutes for up to 30 minutes.  TEMPEST millimeter-wave radiometers scan across track and observe at five frequencies from 87 to 181 GHz, with spatial resolution ranging from 25 km to 13 km, respectively.</p><p>The TEMPEST-D satellite was launched on May 21, 2018 from NASA Wallops to the ISS and was successfully deployed on July 13, 2018, into a 400-km orbit at 51.6° inclination.  The TEMPEST-D sensor has been operating nearly continuously since its first light data on September 5, 2018.  With more than 16 months of operations to date, TEMPEST-D met all of its Level-1 mission objectives within the first 90 days of operations and has successfully achieved TRL 9 for both instrument and spacecraft systems. </p><p>Validation of observed TEMPEST-D brightness temperatures is performed by comparing to coincident observations by well-calibrated on-orbit instruments, including GPM/GMI and MHS on NOAA-19, MetOp-A and MetOp-B satellites. Absolute calibration accuracy is within 0.9 K for all except the…
Journal of Atmospheric and Oceanic Technology
The rapid development of miniaturized satellite instrument technology has created a new opportuni... more The rapid development of miniaturized satellite instrument technology has created a new opportunity to deploy constellations of passive microwave (PMW) radiometers to permit retrievals of the same Earth scene with very high temporal resolution to monitor cloud evolution and processes. In order for such a concept to be feasible, it must be shown that it is possible to distinguish actual changes in the atmospheric state from the variability induced by making observations at different Earth incidence angles (EIAs). To this end, we present a flexible and physical optimal estimation-based algorithm designed to retrieve profiles of atmospheric water vapor, cloud liquid water path, and cloud ice water path from cross-track PMW sounders. The algorithm is able to explicitly account for the dependence of forward model errors on EIA and atmospheric regime. When the algorithm is applied to data from the Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) Cub...
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
CubeSats and NanoSats for Remote Sensing, 2016
2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2016
2016 IEEE MTT-S International Microwave Symposium (IMS), 2016
2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2016
Igarss 2008 2008 Ieee International Geoscience and Remote Sensing Symposium, Jul 7, 2008
ABSTRACT Quantitative precipitation forecasting is currently limited by the paucity of observatio... more ABSTRACT Quantitative precipitation forecasting is currently limited by the paucity of observations of thermodynamic variables in the troposphere, including water vapor. Specifically, measurements of 3-D water vapor fields are needed at sub-meso-gamma scales in pre- storm conditions. This can be achieved using a network of remote sensors to retrieve the water vapor field with high spatial and temporal resolution. Such measurements may be used for assimilation into and validation of numerical weather prediction (NWP) models. Conventional measurements of water vapor density profiles are obtained using in-situ probes on-board weather balloons, including radiosondes. Remote sensing techniques to retrieve moisture profiles include ground-based networks receiving Global Navigation Satellite Systems (GNSS) signals, including GPS, and GPS receivers aboard the COSMIC satellite constellation for atmospheric occultation. These methods provide measurements with high vertical resolution but with coarse horizontal resolution. Differential Absorption Lidars (DIAL) can retrieve water vapor with comparable resolution to that of radiosonde observations. However, these lidars are expensive, and their operation is limited to clear-sky conditions due to the high opacity of clouds at optical wavelengths. Inversion of brightness temperatures measured by upward- looking, ground-based microwave radiometers allows the estimation of vertical profiles with high temporal resolution in both clear and cloudy conditions. However, assimilation of retrieved 3-D water vapor fields with improved spatial coverage into NWP models in pre-storm conditions has the potential for substantial impact on numerical weather prediction of convective storm activity. Measurements using a network of multi-frequency microwave radiometers can provide the necessary information to retrieve the 3-D distribution of water vapor in the troposphere.
ABSTRACT: WindSat, the first polarimetric microwave radiometer on orbit, and the NPOESS Conical M... more ABSTRACT: WindSat, the first polarimetric microwave radiometer on orbit, and the NPOESS Conical Microwave Imager/Sounder,