PRELIMINARY INVESTIGATION OF SPLASH EFFECT ON HIGH WIND C-BAND HH-POL MODEL FUNCTION

The National Research Council Decadal Survey [1] identified a need for a future mission that would provide accurate real-time observations of ocean wind vectors from calm to tropical cyclone wind conditions with and without presence of rain. Tasked by National Oceanic and Atmospheric Administration (NOAA), the Jet Propulsion Laboratory (JPL) developed a future scatterometer design that would leverage its success on the heritage of QuikSCAT but would provide more accurate measurements under all weather conditions through use of Ku-and C-band coincident measurements of the ocean surface. To design a cost effective instrument for all weather operations from space the existing risks need to be mitigated. The work described in this paper attempts to validate results reported at hurricane strength winds i

Extrem, o no tan extrem, aquesta és la qüestió

3 pages, 2 figures[EN] This proves to be a question that is difficult to answer, but has far-reaching consequences for satellite meteorology, weather forecasting, oceanography, climate and hurricane advisories. Hurricanes are among the deadliest of the existing natural disasters, moreover causing formidable economic losses (Bevere et al. 2020). Accurate, short- and medium-range forecasting of their intensity and track (among others) are therefore essential to mitigate human and economic losses. In the longer range, it is also important to understand whether extreme weather conditions are becoming more extreme in a changing climate, stirring deeper waters in the ocean and hence affecting climate system dynamics. Unfortunately, tropical circulation conditions, such as El Niño and the Madden Julian Oscillation, are associated with large year-to-year variability in extreme wind speed distribution and their link to climate change is poorly understood, limiting our ability to determine whether the hurricane climatology is actually changing or not. […][ES] Esta es una pregunta difícil de responder, pero que tiene consecuencias de gran alcance para la meteorología satelital, la previsión meteorológica, la oceanografía, el clima y los programas de aviso de huracanes. Los huracanes se encuentran entre los desastres naturales más mortíferos y, además, causan enormes pérdidas económicas (Bevere et al. 2020). Por lo tanto, una predicción precisa de su intensidad y trayectoria a corto y medio plazo son esenciales para mitigar las pérdidas humanas y económicas. A más largo plazo, también es importante comprender si las condiciones meteorológicas extremas se están volviendo más extremas en el contexto del cambio climático, llegando a perturbar aguas más profundas y, por lo tanto, afectando la dinámica del sistema climático entero. Desafortunadamente, fenómenos como El Niño y la Oscilación de Madden-Julian, están asociados a una gran variabilidad interanual en la distribución de la intensidad de vientos extremos, con una dependencia del cambio climático todavía poco clara, limitando así nuestra capacidad para determinar si la climatología de huracanes en realidad está cambiando o no. […][CAT] Aquesta és una pregunta difícil de respondre, però que té conseqüències de gran abast per a la meteorologia satel·litària, la previsió meteorològica, l’oceanografia, el clima i els programes d’avís d’huracans. Els huracans es troben entre els desastres naturals més mortífers i, a més, causen enormes pèrdues econòmiques (Bevere et al. 2020). Per tant, una predicció precisa de la seva intensitat i trajectòria a curt i mitjà termini són essencials per a mitigar les pèrdues humanes i econòmiques. A més llarg termini, també és important comprendre si les condicions meteorològiques extremes s’estan tornant més extremes en el context del canvi climàtic, arribant a pertorbar aigües més profundes i, per tant, afectant la dinàmica del sistema climàtic sencer. Desafortunadament, fenòmens com El Niño i l’Oscil·lació de Madden-Julian estan associats a una gran variabilitat interanual en la distribució de la intensitat de vents extrems, amb una dependència del canvi climàtic encara poc clara, limitant així la nostra capacitat per a determinar si la climatologia d’huracans en realitat està canviant o no. […]Peer reviewe

Measuring Winds From Space to Reduce the Uncertainty in the Southern Ocean Carbon Fluxes: Science Requirements and Proposed Mission

Strong winds in Southern Ocean storms drive air-sea carbon and heat fluxes. These fluxes are integral to the global climate system and the wind speeds that drive them are increasing. The current scatterometer constellation measuring vector winds remotely undersamples these storms and the higher winds within them, leading to potentially large biases in Southern Ocean wind reanalyses and the fluxes that derive from them. This observing system design study addresses these issues in two ways. First, we describe an addition to the scatterometer constellation, called Southern Ocean Storms -- Zephyr, to increase the frequency of independent observations, better constraining high winds. Second, we show that potential reanalysis wind biases over the Southern Ocean lead to uncertainty over the sign of the net winter carbon flux. More frequent independent observations per day will capture these higher winds and reduce the uncertainty in estimates of the global carbon and heat budgets

An Ocean Surface Wind Vector Model Function For A Spaceborne Microwave Radiometer

Surface wind vector measurements over the oceans are vital for scientists and forecasters to understand the Earth\u27s global weather and climate. In the last two decades, operational measurements of global ocean wind speeds were obtained from passive microwave radiometers (Special Sensor Microwave/Imagers); and over this period, full ocean surface wind vector data were obtained from several National Aeronautics and Space Administration and European Space Agency scatterometry missions. However, since SeaSat-A in 1978, there have not been other combined active and passive wind measurements on the same satellite until the launch of Japan Aerospace Exploration Agency\u27s Advanced Earth Observing Satellite-II in 2002. This mission provided a unique data set of coincident measurements between the SeaWinds scatterometer and the Advanced Microwave Scanning Radiometer (AMSR). The AMSR instrument measured linearly polarized brightness temperatures (TB) over the ocean. Although these measurements contained wind direction information, the overlying atmospheric influence obscured this signal and made wind direction retrievals not feasible. However, for radiometer channels between 10 and 37 GHz, a certain linear combination of vertical and horizontal brightness temperatures causes the atmospheric dependence to cancel and surface parameters such as wind speed and direction and sea surface temperature to dominate the resulting signal. In this paper, an empirical relationship between AMSR TB\u27s (specifically A • TBv - TBH) and surface wind vectors (inferred from SeaWinds\u27 retrievals) is established for three microwave frequencies: 10, 18, and 37 GHz. This newly developed wind vector model function for microwave radiometers can serve as a basis for wind vector retrievals either separately or in combination with active scatterometer measurements. © 2007 IEEE

A Novel Active And Passive Microwave Remote Sensing Technique For Measuring Ocean Surface Wind Vector

This paper describes a novel technique of ocean surface vector wind measurement using active and passive microwave sensing from a satellite. For over a decade, satellite microwave scatterometers have remotely sensed ocean wind vector (speed and direction) by measuring ocean radar backscatter (sigma-0) at several different azimuth angles (looking forward and aft). Also, ocean wind speeds have been measured by conical scanning passive microwave radiometers looking either forward or aft. This paper combines these two techniques to obtain wind speed and direction from a conical scanning instrument that scans either forward or aft, which is extremely desirable from an instrument design and satellite accommodations standpoint. An overview of the active/passive wind vector algorithm is discussed, and wind vector retrievals are presented using microwave measurements from Japan\u27s ADEOS-II satellite. These results are compared with wind vectors from the SeaWinds scatterometer

Development of Oceanic Wind Vector Model Function for AMSR Radiometer on ADEOS-II Satellite

Since the advent of the first spaceborne wind scatterometers on NASA\u27s SeaSat mission in 1978, the Advanced Earth Observing Satellite (ADEOS)-II was the first satellite mission that carried both microwave scatterometer and radiometer imagers. This provided a unique opportunity to explore the possibility of combined technology for oceanic surface wind vector measurements. In contrast to conventional scatterometry that require both forward and aft multi-azimuth look measurements, our technique use only forward look radar backscatter measurement combine with collocated brightness temperature measurements to retrieve wind direction. This single-look configuration would be highly beneficial for future satellite mission to obtain improved observation of both oceanic and atmospheric information. Microwave radiometers are well-known instrument for atmospheric and oceanic physical parameters retrieval. Although, the vertical and horizontal brightness temperatures are weakly dependent on wind direction, it has been shown that certain linear combinations of vertical and horizontal brightness temperatures are almost indepentdent of the atmosphere and are predominantly a function of wind speed, direction and sea surface temperature (SST). The empirical relationship for these brightness temperatures was developed for the Advaced Microwave Scanning Radiometer (AMSR) on ADEOS-II. In addition to passive measurement, coincident radar backscatter from foreward look SeaWinds scatterometer was combined to retrieve the wind directions. The wind direction retrieval algorithm and statistical results are presented

Development Of Oceanic Wind Vector Model Function For Amsr Radiometer On Adeos-Ii Satellite

Since the advent of the first spaceborne wind scatterometers on NASA\u27s SeaSat mission in 1978, the Advanced Earth Observing Satellite (ADEOS)-II was the first satellite mission that carried both microwave scatterometer and radiometer imagers. This provided a unique opportunity to explore the possibility of combined technology for oceanic surface wind vector measurements. In contrast to conventional scatterometry that require both forward and aft multi-azimuth look measurements, our technique use only forward look radar backscatter measurement combine with collocated brightness temperature measurements to retrieve wind direction. This single-look configuration would be highly beneficial for future satellite mission to obtain improved observation of both oceanic and atmospheric information. Microwave radiometers are well-known instrument for atmospheric and oceanic physical parameters retrieval. Although, the vertical and horizontal brightness temperatures are weakly dependent on wind direction, it has been shown that certain linear combinations of vertical and horizontal brightness temperatures are almost indepentdent of the atmosphere and are predominantly a function of wind speed, direction and sea surface temperature (SST). The empirical relationship for these brightness temperatures was developed for the Advaced Microwave Scanning Radiometer (AMSR) on ADEOS-II. In addition to passive measurement, coincident radar backscatter from foreward look SeaWinds scatterometer was combined to retrieve the wind directions. The wind direction retrieval algorithm and statistical results are presented

On Dropsonde Surface-Adjusted Winds and Their Use for the Stepped Frequency Microwave Radiometer Wind Speed Calibration

8 pages, 7 figuresThe airborne stepped frequency microwave radiometer (SFMR) provides the measurements of 10-m ocean surface wind speed in high and extreme wind conditions. These winds are calibrated using the surface-adjusted wind estimates from the so-called dropsondes. The surface-adjusted winds are obtained from layer-averaged winds scaled to 10-m altitude to eliminate the local surface variability not associated with the storm strength. The SFMR measurements and, consequently, the surface-adjusted dropsonde winds represent a possible reference for satellite instrument and model calibration/validation at high and extreme wind conditions. To this end, representativeness errors that those measurements may introduce need to be taken into account to ensure that the storm variability is correctly resolved in satellite retrievals and modeling. In this work, we compare the SFMR winds with the dropsonde surface-adjusted winds derived from the so-called WL150 algorithm, which uses the lowest 150-m layer between 10 and 350 m. We use nine years of data from 2009 to 2017. We focus on the effects of the layer altitude and thickness. Our analysis shows that the layer altitude has a significant impact on dropsonde/SFMR wind comparisons. Moreover, the averaged winds obtained from layers thinner than the nominal 150 m and closer to the surface are more representative of the SFMR surface wind speed than the WL150 speeds. We also find that the surface-adjusted winds are more representative of 10-km horizontally averaged SFMR winds. We conclude that for calibration/validation purposes, the WL150 algorithm can introduce noise, and the use of actual 10-m dropsonde measurements should be further investigatedThis work was supported in part by the MCIN/AEI/10.13039/501100011033 and ERDF A way of making Europe through the Spanish Research and Development Project L-BAND under Grant ESP2017-89463-C3-1-R, in part by the MCIN/AEI/10.13039/501100011033 through the Project INTERACT under Grant PID2020-114623RB-C31, in part by the Spanish Government through the Severo Ochoa Center of Excellence Accreditation under Grant CEX2019-000928-S, in part by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) through the Tender 16_166-STC under C-band High and Extreme- Force Speeds (CHEFS) Project EUM/CO/16/4600001953, and in part by the Jet Propulsion Laboratory, California Institute of Technology, through the National Aeronautics and Space Administration (NASA) Postdoctoral Program (NPP), initially administered by Universities Space Research Association and now administered by Oak Ridge Associated Universities, under a contract with NASAPeer reviewe

On High and Extreme Wind Calibration Using ASCAT

10 pages, 9 figures, 1 tableAccurate high and extreme sea surface wind observations are essential for the meteorological, ocean, and climate applications. To properly assess and calibrate the current and future satellite-derived extreme winds, including those from the C-band scatterometers, building a consolidated high and extreme wind reference data set is crucial. In this work, a new approach is presented to assess the consistency between moored buoys and stepped-frequency microwave radiometer (SFMR)-derived winds. To overcome the absence of abundant direct collocations between these two data sets, the reprocessed Advanced Scatterometer (ASCAT)-A winds at the 12.5-km resolution, from 2009 to 2017, have been used to perform an indirect SFMR/buoy winds’ intercomparison. The ASCAT/SFMR analysis reveals an ASCAT wind underestimation for winds of above 15 m/s. SFMR measurements are calibrated using GPS drop-wind-sondes (dropsondes) data and averaged along-track to represent ASCAT spatially. On the other hand, ASCAT and buoy winds are in good agreement up to 25 m/s. The buoy high-wind quality has been confirmed using a triple collocation approach. Comparing these results, both SFMR and buoy winds appear to be highly correlated with ASCAT at the high-wind regime; however, they show a very different wind speed scaling. An SFMR-based recalibration of ASCAT winds is proposed, the so-called ASCAT dropsonde-scale winds, for use by the extreme wind operational community. However, further work is required to reconcile dropsonde (thus, SFMR) and buoy wind measurements under extreme wind conditionsWith the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Comparison of the Sentinel-1B Synthetic Aperture Radar With Airborne Microwave Sensors in an Extra-Tropical Cyclone

In Winter 2017, the University of Massachusetts Amherst's Imaging Wind and Rain Airborne Profiler (IWRAP) was flown on a National Oceanic and Atmospheric Administration (NOAA) WP-3D Hurricane Hunter aircraft under the direction of scientists from Center for Satellite Applications and Research (STAR) at NOAA/National Environmental Satellite, Data, and Information Service (NESDIS) over the North Atlantic ocean out of Shannon, Ireland. IWRAP is a dual-frequency, conically scanning, profiling Doppler radar initially developed by Microwave Remote Sensing Laboratory (MIRSL) at the University of Massachusetts Amherst that is routinely installed on the NOAA WP-3D research aircraft. The flight on February 6, 2017, targeted a region of high winds (greater than 30 m/s) that was also observed by the Sentinel-1B satellite's synthetic aperture radar. Sentinel-1B was configured to observe in extended wide swath mode in both VV- and VH-polarizations, whereas the IWRAP C-band radar was configured to measure all of VV-, VH-, and HH-polarizations. IWRAP and Sentinel-1B VV and VH normalized radar cross section (NRCS) at the same Earthincidence angle along the flight path match reasonably well during the entire flight, but some additional trends between aircraft and satellite can be observed. IWRAP VV-polarized NRCS generally match the CMOD5.h geophysical model function (GMF), suggesting errors in the Sentinel-1B processing chain