Satellite Remote Sensing of Tropical Cyclones

This chapter provides a review on satellite remote sensing of tropical cyclones (TCs). Applications of satellite remote sensing from geostationary (GEO) and low earth orbital (LEO) platforms, especially from passive microwave (PMW) sensors, are focused on TC detection, structure, and intensity analysis as well as precipitation patterns. The impacts of satellite remote sensing on TC forecasts are discussed with respect to helping reduce the TC\u27s track and intensity forecast errors. Finally, the multi‐satellite‐sensor data fusion technique is explained as the best way to automatically monitor and track the global TC\u27s position, structure, and intensity

S-NPP ATMS Instrument Prelaunch and On-Orbit Performance Evaluation

The first of a new generation of microwave sounders was launched aboard the Suomi-National Polar-Orbiting Partnership satellite in October 2011. The Advanced Technology Microwave Sounder (ATMS) combines the capabilities and channel sets of three predecessor sounders into a single package to provide information on the atmospheric vertical temperature and moisture profiles that are the most critical observations needed for numerical weather forecast models. Enhancements include size/mass/power approximately one third of the previous total, three new sounding channels, the first space-based, Nyquist-sampled cross-track microwave temperature soundings for improved fusion with infrared soundings, plus improved temperature control and reliability. This paper describes the ATMS characteristics versus its predecessor, the advanced microwave sounding unit (AMSU), and presents the first comprehensive evaluation of key prelaunch and on-orbit performance parameters. Two-year on-orbit performance shows that the ATMS has maintained very stable radiometric sensitivity, in agreement with prelaunch data, meeting requirements for all channels (with margins of ~40% for channels 1-15), and improvements over AMSU-A when processed for equivalent spatial resolution. The radiometric accuracy, determined by analysis from ground test measurements, and using on-orbit instrument temperatures, also shows large margins relative to requirements (specified as <1.0K for channels 1, 2, and 16-22 and <0.75 K for channels 3-15). A thorough evaluation of the performance of ATMS is especially important for this first proto-flight model unit of what will eventually be a series of ATMS sensors providing operational sounding capability for the U.S. and its international partners well into the next decade

Implementation of a Discrete Dipole Approximation Scattering Database Into Community Radiative Transfer Model

The Community Radiative Transfer Model (CRTM) is a fast model that requires bulk optical properties of hydrometeors in the form of lookup tables to simulate all-sky satellite radiances. Current cloud scattering lookup tables of CRTM were generated using the Mie-Lorenz theory thus assuming spherical shapes for all frozen habits, while actual clouds contain frozen hydrometeors with different shapes. The Discrete Dipole Approximation (DDA) technique is an effective technique for simulating the optical properties of non-spherical hydrometeors in the microwave region. This paper discusses the implementation and validation of a comprehensive DDA cloud scattering database into CRTM for the microwave frequencies. The original DDA database assumes total random orientation in the calculation of single scattering properties. The mass scattering parameters required by CRTM were then computed from single scattering properties and water content dependent particle size distributions. The new lookup tables eliminate the requirement for providing the effective radius as input to CRTM by using the cloud water content for the mass dimension. A collocated dataset of short-term forecasts from Integrated Forecast System of the European Center for Medium-Range Weather Forecasts and satellite microwave data was used for the evaluation of results. The results overall showed that the DDA lookup tables, in comparison with the Mie tables, greatly reduce the differences among simulated and observed values. The Mie lookup tables especially introduce excessive scattering for the channels operating below 90\ua0GHz and low scattering for the channels above 90\ua0GHz

An Overview of Suomi NPP VIIRS Calibration Maneuvers

The first Visible Infrared Imager Radiometer Suite (VIIRS) instrument was successfully launched on-board the Suomi National Polar-orbiting Partnership (SNPP) spacecraft on October 28, 2011. Suomi NPP VIIRS observations are made in 22 spectral bands, from the visible (VIS) to the long-wave infrared (LWIR), and are used to produce 22 Environmental Data Records (EDRs) with a broad range of scientific applications. The quality of these VIIRS EDRs strongly depends on the quality of its calibrated and geo-located Sensor Date Records (SDRs). Built with a strong heritage to the NASA's EOS MODerate resolution Imaging Spectroradiometer (MODIS) instrument, the VIIRS is calibrated on-orbit using a similar set of on-board calibrators (OBC), including a solar diffuser (SD) and solar diffuser stability monitor (SDSM) system for the reflective solar bands (RSB) and a blackbody (BB) for the thermal emissive bands (TEB). On-orbit maneuvers of the SNPP spacecraft provide additional calibration and characterization data from the VIIRS instrument which cannot be obtained pre-launch and are required to produce the highest quality SDRs. These include multi-orbit yaw maneuvers for the characterization of SD and SDSM screen transmission, quasi-monthly roll maneuvers to acquire lunar observations to track sensor degradation in the visible through shortwave infrared, and a driven pitch-over maneuver to acquire multiple scans of deep space to determine TEB response versus scan angle (RVS). This paper pro-vides an overview of these three SNPP calibration maneuvers. Discussions are focused on their potential calibration and science benefits, pre-launch planning activities, and on-orbit scheduling and implementation strategies. Results from calibration maneuvers performed during the Intensive Calibration and Validation (ICV) period for the VIIRS sensor are illustrated. Also presented in this paper are lessons learned regarding the implementation of calibration spacecraft maneuvers on follow-on missions

Access to financial services: towards an understanding of the role and impact of financial exclusion in Sub-Saharan Africa

This thesis investigates the nature and extent of financial inclusion in Sub-Saharan Africa (SSA). It sequentially investigates this in three related studies. The first study examines the impact of access to finance on poverty, while the second investigates the extent to which cross-country structural and macroeconomic variations contribute to the observed variations in the levels of financial inclusion. Finally, because both financial inclusion and financial stability have been embraced as key policy initiatives over the past decade, the third study examines the nature of relationship between these two policy goals. The first paper uses household-level data from FinScope Surveys conducted in eight SSA countries between 2014 and 2015 to examine the impact of access to finance on household wealth. The few studies which have looked at this relationship in the past apply a linear estimation and thus inadvertently assume a uniform distribution across all levels of poverty. This study examines the heterogeneous impact of access to finance along the entire wealth distribution line using a Re-centered Influence Function (RIF) regression model. Further, to eliminate potential endogeneity, an instrumental variable quantile approach is implemented. Results from both estimations indicate that the unconditional effect of access to finance on poverty is non-monotonic. For most of the countries, the effect is highest at the median level, and very low at the bottom of the wealth index. This suggests that the extension of formal financial services disproportionately benefits the middle-class more than the very-poor and rich categories. The second paper uses macroeconomic data obtained from various World Bank databases over the period 2004-2014 to examine the extent to which the observed cross-country variations in financial inclusion are mirrored by country-specific structural and macroeconomic characteristics. To conceptualize, the study uses a benchmark model to establish the optimal level of financial inclusion given the country's fundamentals, and thus provide a meaningful cross-country comparison. The key structural and policy factors that determine the extent of the gap between the actual and predicted levels of access to finance are analysed via a fixed-effects model based on selected SSA countries. The results suggest the existence of a gap in access to finance within the region, compared to their potential. The gap is wider in banking systems with high concentration, low proportion of foreign banks and poor economic conditions. The final paper empirically examines the theoretical ambiguity between financial inclusion and stability. Theory provides conflicting views on whether the two are complimentary, or mutually exclusive. This paper examines this dynamic relationship via a system-GMM panel estimation model using a panel of 40 countries from the SSA region over the period 2004-2014, while controlling for both bank-specific and macroeconomic-wide factors. The results indicate that financial inclusion has a positive impact on bank stability, however, high market power within the banking systems and poor institutional framework tends to undermine the impact of financial inclusion on stability. Overall, the results provide evidence that the existing portfolio of formal financial services does not provide sustainable solutions to poverty eradication in terms of meeting the unique needs of the poorer members of the societies. This ultimately widens the gap between the poorest and the middle-class which further complicates the poverty structure. Therefore, there is a need for more investment on improving both the range of existing product offering and the financial capabilities of the poor, in order to improve their participation in financial markets. Demand-side policies should focus on increasing the bankable population by improving both awareness and usage of financial services and products. Supply-side policies should seek to eliminate market frictions by reducing concentration levels, improve competiveness through relaxation of entry restrictions, and opening the market to foreign institutes and non-banking players, and thus improve innovation in both new products offering and service delivery. This work further argues that financial inclusion is not only a developmental or welfare issue, but has positive ramifications on the banking system. Therefore, to be effective financial inclusion policies should adopt a market systems approach to development, which recognizes the importance of support structures and seek to benefit the poor by incentivizing service providers to improve product quality, variety and returns, and thus create value throughout the value chain. An effective approach should also embrace the role of macro-prudential regulatory and supervisory framework, as an indispensable tool, not only in governing the behavior of financial services providers, but because of its efficacy in building consumer confidence- a key element for increased access and usage of financial services

CIRA annual report FY 2017/2018

Reporting period April 1, 2017-March 31, 2018

On-orbit Inter-satellite Radiometric Calibration of Cross-track Scanning Microwave Radiometers

This dissertation concerns the development of an improved algorithm for the inter-satellite radiometric calibration (XCAL) for cross track scanning microwave radiometers in support of NASA\u27s Global Precipitation Mission (GPM). This research extends previous XCAL work to assess the robustness of the CFRSL double difference technique for sounder X-CAL. In this work, using a two-year of observations, we present a statistical analysis of radiometric biases performed over time and viewing geometry. In theory, it is possible to apply the same X-CAL procedure developed for conical-scanning radiometers to cross-track scanners; however the implementation is generally more tedious. For example, with the cross-track scan angle, there is a strong response in the observed Tb due to changes in the atmosphere slant path and surface emissivity with the Earth incidence angle. For ocean scenes this is trivial; however for land scenes there is imperfect knowledge of polarized emissivity. However, for the sounder channels the surface emissivity is not the dominant component of top-of-the-atmosphere Tb, which is a mitigating factor. Also, cross-track scanners introduce changes in the radiometer antenna observed polarization with scan angle. The resulting observation is a mixture of un-polarized atmospheric emissions and vertical and horizontal polarized surface emissions. The degree of polarization mixing is known from geometry; however, reasonable estimates of the surface emissivity are required, which complicate over land comparisons. Finally, the IFOV size monotonically increases over the cross-track scan. Thus, when inter-comparing cross-track scanning radiometers, it will be necessary to carefully consider these effects when performing the double difference procedure

Introducing hydrometeor orientation into all-sky microwave and submillimeter assimilation

Numerical weather prediction systems still employ many simplifications when assimilating microwave radiances under all-sky conditions (clear sky, cloudy, and precipitation). For example, the orientation of ice hydrometeors is ignored, along with the polarization that this causes. We present a simple approach for approximating hydrometeor orientation, requiring minor adaption of software and no additional calculation burden. The approach is introduced in the RTTOV (Radiative Transfer for TOVS) forward operator and tested in the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). For the first time within a data assimilation (DA) context, this represents the ice-induced brightness temperature differences between vertical (V) and horizontal (H) polarization-the polarization difference (PD). The discrepancies in PD between observations and simulations decrease by an order of magnitude at 166.5 GHz, with maximum reductions of 10-15 K. The error distributions, which were previously highly skewed and therefore problematic for DA, are now roughly symmetrical. The approach is based on rescaling the extinction in V and H channels, which is quantified by the polarization ratio. Using dual-polarization observations from the Global Precipitation Mission microwave imager (GMI), suitable values for were found to be 1.5 and 1.4 at 89.0 and 166.5 GHz, respectively. The scheme was used for all the conical scanners assimilated at ECMWF, with a broadly neutral impact on the forecast but with an increased physical consistency between instruments that employ different polarizations. This opens the way towards representing hydrometeor orientation for cross-track sounders and at frequencies above 183.0 GHz where the polarization can be even stronger