Recent technology advances in miniature microwave radiometers that can be hosted on very small satellites has made possible a new class of affordable constellation missions that provide very high revisit rates of tropical cyclones and other severe weather. The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA as part of the Earth Venture–Instrument (EVI-3) program and is now in development with planned launch readiness in late 2019. The overarching goal for TROPICS is to provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones (TCs). TROPICS will provide rapid-refresh microwave measurements (median refresh rate better than 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. TROPICS will comprise a constellation of at least six CubeSats in three low-Earth orbital planes. Each CubeSat will host a high performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles and low-level moisture. This observing system offers an unprecedented combination of horizontal and temporal resolution in the microwave spectrum to measure environmental and inner-core conditions for TCs on a nearly global scale and is a major leap forward in the temporal resolution of several key parameters needed for assimilation into advanced data assimilation systems capable of utilizing rapid-update radiance or retrieval data. Here, we provide an overview of the mission and an update on current status, with a focus on unique characteristics of the Cubesat system, recent performance simulations on a range of observables to be provided by the constellation, and a summary of science applications.
Top-of-atmosphere radiances and adjoint sensitivities for ice clouds at 600-2300 cm-1 are studied using a new fast radiative transfer system (forward, tangent linear, and adjoint) developed for the NASA/NOAA/DOD Joint Center for Satellite Data Assimilation. The radiative transfer model is based on a hybrid solution method for computing thermal radiances that fully accounts for multiple scattering and that allows clouds to be placed at any number of arbitrary layers. Called the successive order of interaction model, it has been shown to be faster in most cases and more accurate than the popular delta-Eddington model. Ice particle scattering properties are obtained from rigorous scattering theory for various particle shapes and sizes. Gas optical depths are derived from line-by-line calculations. Results indicate that top-of-atmosphere brightness temperatures are sensitive to ice water path occurring in multiple cloud layers, which suggests major challenges for retrieving cloud properties under conditions other than single-layered clouds.
A new, fast radiative transfer model including scattering
has been developed for the purpose of microwave radiance assimilation
in cloudy and precipitating areas. The model uses a technique called
successive order of interaction (SOI) which is based on a blending of the doubling and the successive order of scattering techniques. An adjoint and tangent linear version of the model are also available. Within this paper we present first applications of the SOI model. We compare brightness temperatures simulated from NCEP's Global Forecasting System (GFS) using a non-scattering version of the SOI model with global satellite data obtained by the Advanced Scanning Microwave Radiometer (AMSR-E) onboard NASA's Aqua spacecraft. Additionally, we show first sensitivity studies using the
adjoint model for cases that include scattering by liquid and frozen
The International MODIS (Moderate Resolution Imaging Spectroradiometer) and AIRS (Atmospheric Infrared Sounder) Processing Package (IMAPP) is supported by NASA with the goals of developing a software package which is freely available for processing MODIS and AIRS/AMSU/HSB Data and promoting and supporting the worldwide use of EOS data, and involving the international community in EOS validation efforts. Both NASA's TERRA and AQUA spacecrafts have direct broadcast (DB) X-band downlinks that allow MODIS (on board both TERRA and AQUA) and AIRS/AMSU/HSB and AMSR-E (on board AQUA only) data to be received in real time by sites having the proper reception hardware. In addition to the current released IMAPP, which allows ground stations capable of receiving EOS direct broadcast data to generate products derived from MODIS and AIRS/AMSU/HSB, products from AMSR-E are under developed. Comparison of one month direct broadcast AMSR-E level 1 data with standard AMSR-E level 2A (level 1 data embedded) data archived by MSFC, NASA, have been carried out and the results have shown that the DB level 1 implementation successfully matches the standard products of brightness temperatures in terms of bias, RMS errors and correlation coefficients, i.e., the DB level 1 data are well calibrated and geo-located and are ready for retrieval for geophysical products. The AMSR-E level 2 products for precipitation and soil moisture are currently under evaluation. Those products will be compared with and validated against the official products.
Conference Committee Involvement (1)
Microwave Remote Sensing of the Atmosphere and Environment IV
9 November 2004 | Honolulu, Hawai'i, United States