CYGNSS Surface Heat Flux Product Development

Crespo, Juan A.; Posselt, Derek J.; Asharaf, Shakeel

doi:10.3390/rs11192294

Cited by 24 publications

(27 citation statements)

References 37 publications

(60 reference statements)

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“…Exploring the effects of the atmosphere-ocean conditions on the observed wind speeds is crucial. Biases introduced by air-sea state and exchange processes have the potential to introduce biases into the applications of wind-derived products, such as in the estimation of surface heat fluxes (Crespo et al 2019). To assess the potential impact of these conditions on the matchups, wind difference residuals are regressed against a number of air-sea conditions.…”

Section: B Effects Of the Air-sea Statementioning

confidence: 99%

CYGNSS Ocean Surface Wind Validation in the Tropics

Asharaf

Waliser

Posselt

et al. 2021

Journal of Atmospheric and Oceanic Technology

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Surface wind plays a crucial role in many local/regional weather and climate processes, especially through the exchanges of energy, mass and momentum across the Earth’s surface. However, there is a lack of consistent observations with continuous coverage over the global tropical ocean. To fill this gap, the NASA Cyclone Global Navigation Satellite System (CYGNSS) mission was launched in December 2016, consisting of a constellation of eight small spacecrafts that remotely sense near surface wind speed over the tropical and sub-tropical oceans with relatively high sampling rates both temporally and spatially. This current study uses data obtained from the Tropical Moored Buoy Arrays to quantitatively characterize and validate the CYGNSS derived winds over the tropical Indian, Pacific, and Atlantic Oceans. The validation results show that the uncertainty in CYGNSS wind speed, as compared with these tropical buoy data, is less than 2 m s-1 root mean squared difference, meeting the NASA science mission Level-1 uncertainty requirement for wind speeds below 20 m s-1. The quality of the CYGNSS wind is further assessed under different precipitation conditions, and in convective cold-pool events, identified using buoy rain and temperature data. Results show that CYGNSS winds compare fairly well with buoy observations in the presence of rain, though at low wind speeds the presence of rain appears to cause a slight positive wind speed bias in the CYGNSS data. The comparison indicates the potential utility of the CYGNSS surface wind product, which in turn may help to unravel the complexities of air-sea interaction in regions that are relatively under-sampled by other observing platforms.

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Section: B Effects Of the Air-sea Statementioning

confidence: 99%

CYGNSS Ocean Surface Wind Validation in the Tropics

Asharaf

Waliser

Posselt

et al. 2021

Journal of Atmospheric and Oceanic Technology

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“…The CYGNSS wind speed products used here are estimated assuming that the sea state is in equilibrium with the wind speed, or "fully developed seas," which is the preferred product to be used over most of the tropics away from tropical cyclones (Clarizia et al, 2018). We also use the Level 2 surface latent heat flux product derived from CYGNSS wind speed coupled with thermodynamic variables from reanalysis data, as described by Crespo et al (2019). This surface flux product was generated from CYGNSS version 2.1 wind speed, and a flux product is not available for CDR version 1.0.…”

Section: Datamentioning

confidence: 99%

“…In the present study, wind-induced surface flux feedbacks and their effect on the MJO are investigated in the Cyclone Global Navigation Satellite System (CYGNSS; Ruf et al, 2016) data set and an associated latent heat flux data set derived from this (Crespo et al, 2019). CYGNSS is a relatively new tool (i.e., launched in December 2016) that can be utilized to address outstanding MJO questions related to surface feedbacks as it can provide better spatial and temporal resolution of surface wind speed over the tropical oceans than other satellite retrieval platforms.…”

Section: Introductionmentioning

confidence: 99%

Wind Speed, Surface Flux, and Intraseasonal Convection Coupling From CYGNSS Data

Bui

Maloney

Dellaripa

et al. 2020

Geophysical Research Letters

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This study analyzes wind speed and surface latent heat flux anomalies from the Cyclone Global Navigation Satellite System (CYGNSS), aiming to understand the physical mechanisms regulating intraseasonal convection, particularly associated with the Madden-Julian oscillation (MJO). An advantage of CYGNSS compared to other space-based data sets is that its surface wind speed retrievals have reduced attenuation by precipitation, thus providing improved information about the importance of wind-induced surface fluxes for the maintenance of convection. Consistent with previous studies from buoys, CYGNSS shows that enhanced MJO precipitation is associated with enhanced wind speeds, and that associated surface heat flux anomalies have a magnitude about 7-12% of precipitation anomalies. Thus, latent heat flux anomalies are an important maintenance mechanism for MJO convection through the column moist static energy budget. A composite analysis during boreal summer over the eastern north Pacific also supports the idea that wind-induced surface flux is important for MJO maintenance there. Plain Language Summary Enhanced surface evaporation (equivalent to a term called latent heat flux) during high wind speed periods can support precipitation through atmospheric moistening. Such evaporation anomalies form a key air-sea interaction component of the Madden-Julian oscillation (MJO). Based on the wind speed and related evaporation anomalies derived from Cyclone Global Navigation Satellite System (CYGNSS) measurements, we show that (1) enhanced MJO precipitation is associated with enhanced wind speed and surface evaporation that may help support the MJO in the Indo-Pacific warm pool and (2) enhanced local surface evaporation is important for maintenance of the MJO over the eastern north Pacific during Northern Hemisphere summer. These results verify results from previous buoy studies that suggest the importance of enhanced wind-driven surface evaporation for maintaining the MJO.

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“…This product (Figure 4) was released through the PODAAC during the last fall, with data availability from March 2017 through the present [24]. An ocean surface heat flux product was released in August 2019, which combines CYGNSS L2 winds with reanalysis data from Modern-Era Retrospective analysis for Research and Applications (MERRA-2) in order to estimate the latent and sensible heat fluxes at each CYGNSS specular point [25]. An update of L2 CDR v1.0 of the CYGNSS ocean surface heat flux product was released in October 2020.…”

mentioning

confidence: 99%

“…At the time of the meeting, the L1 ocean product remained the most popular CYGNSS product being downloaded, and the CYGNSS usage from October 2019 to May 2020 rebounded to pre-FTP retirement levels. It was also noted that by early 2021, cloud services for select An ocean surface heat flux product was released in August 2019, which combines CYGNSS L2 winds with reanalysis data from Modern-Era Retrospective analysis for Research and Applications (MERRA-2) in order to estimate the latent and sensible heat fluxes at each CYGNSS specular point [25]. An update of L2 CDR v1.0 of the CYGNSS ocean surface heat flux product was released in October 2020.…”

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confidence: 99%

The CYGNSS Mission: On-Going Science Team Investigations

et al. 2021

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In 2012, the National Aeronautics and Space Administration (NASA) selected the CYclone Global Navigation Satellite System (CYGNSS) mission coordinated by the University of Michigan (UM) as a low-cost and high-science Earth Venture Mission. The CYGNSS mission was originally proposed for ocean surface wind speed estimation over Tropical Cyclones (TCs) using Earth-reflected Global Positioning System (GPS) signals, as signals of opportunity. The orbital configuration of each CYGNSS satellite is a circular Low Earth Orbit (LEO) with an altitude ~520 km and an inclination angle of ~35°. Each single Delay Doppler Mapping Instrument (DDMI) aboard the eight CYGNSS microsatellites collects forward scattered signals along four specular directions (incidence angle of the incident wave equals incidence angle of the reflected wave) corresponding to four different transmitting GPS spacecrafts, simultaneously. As such, CYGNSS allows one to sample the Earth’s surface along 32 tracks simultaneously, within a wide range of the satellites’ elevation angles over tropical latitudes. Following the Earth Science Division 2020 Senior Review, NASA announced recently it is extending the CYGNSS mission through 30 September 2023. The extended CYGNSS mission phase is focused on both ocean and land surface scientific investigations. In addition to ocean surface wind speed estimation, CYGNSS has also shown a significant ability to retrieve several geophysical parameters over land surfaces, such as Soil Moisture Content (SMC), Above Ground Biomass (AGB), and surface water extent. The on-going science team investigations are presented in this article.

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CYGNSS Surface Heat Flux Product Development

Cited by 24 publications

References 37 publications

CYGNSS Ocean Surface Wind Validation in the Tropics

CYGNSS Ocean Surface Wind Validation in the Tropics

Wind Speed, Surface Flux, and Intraseasonal Convection Coupling From CYGNSS Data

The CYGNSS Mission: On-Going Science Team Investigations

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