The characterization and impact of Aeolus wind profile observations in NOAA's regional tropical cyclone model (HWRF)

Abstract

Observation system experiments (OSEs) are conducted to assess the potential impacts of horizontal line‐of‐sight wind profile observations from the Aeolus satellite on tropical cyclone (TC) forecasting. The OSEs utilize the operational Hurricane Weather and Research Forecasting (HWRF) model. The OSEs include 226 forecasts from seven TC cases in the Atlantic and Eastern Pacific basins. Comparisons between Aeolus and model background winds show that winds from Aeolus are consistently stronger than those from HWRF. Data assimilation statistics also demonstrate that the greatest potential impacts from the assimilation of Aeolus observations are likely to occur in the upper troposphere and lower stratosphere and within approximately 500 km from the TC centre. For TC forecasting applications, the assimilation of Aeolus observations improves TC intensity and size forecasts in the Eastern Pacific basin, while the results for track forecasts and results from the Atlantic basin are mixed. However, in both basins, the largest and most statistically significant, positive impacts from the assimilation of Aeolus observations occur when reconnaissance flight data are unavailable and during the early stages of TC development. The traditionally used forecast assessments of TC intensity, track and size are rooted in surface‐based metrics, and an additional investigation above the surface demonstrated larger improvements from assimilating Aeolus observations on TC wind structure above 400 hPa as compared to the lower troposphere. Several, different assessments throughout this study demonstrate higher uncertainty and the need for special consideration associated with assimilation techniques within 500 km from the TC centre.

The impacts of assimilating Aeolus horizontal line-of-sight winds on numerical predictions of Hurricane Ida (2021) and a mesoscale convective system over the Atlantic Ocean

“…Figure 8 (c) compares vertical cross sections of zonal wind increments along the selected Aeolus descending measurement swath on 25 August 2021, 12:00:00 UTC, between experiments 2418 and 2418_L2B. The significant impacts of assimilating Aeolus HLOS winds on the analysis increments of zonal winds are located at the upper troposphere (near the cloud top), especially near the center of Ida (2021), which is consistent withMarinescu et al (2022), andGarrett et al (2022). As shown by Fig.8 (c), the difference in the analysis increments of the zonal winds is negative at the cloud tops near the center of Ida (2021) due to the positive analysis increments of Mie-cloudy and Rayleigh-clear winds (descending orbit).…”

Assessing the benefit of variational quality control for assimilating Aeolus Mie and Rayleigh wind profiles in NOAA's global forecast system during tropical cyclones

“…The observation increment of Aeolus profiles was comparable to that in the other wind‐observing systems, in both the AEOLUS and AEOLUS+ VarQC experiments. A reversal in the profile magnitudes for Mie‐cloudy and Rayleigh‐clear is in agreement with other studies (e.g., Marinescu et al ., 2022), indicating that Mie‐cloudy winds were more biased in the upper atmosphere where the retrieval algorithm has errors due to processing of faster winds and the Rayleigh‐clear winds were more biased in the lower atmospheric levels due to the interaction with clouds and surface. The week‐long average also revealed larger RMS error values in AEOLUS + VarQC compared to the AEOLUS experiment.…”

“…We followed a verification approach similar to that in the Marinescu et al . (2022) study and evaluated the impact of assimilating Aeolus data on GFS_v16.0 forecasts of relevant tropical cyclone metrics using scorecards. Seven metrics were used to evaluate storm track, intensity, and TC size.…”

“…Even though Aeolus observations are not assimilated operationally at the National Oceanic and Atmospheric Administration (NOAA), several studies have demonstrated the value of this dataset in improving global weather forecast skill using earlier versions of the National Centers for Environmental Prediction/Global Forecast System with the Cubed Sphere dynamical core (NCEP/GFS‐FV3, Liu et al ., 2022, Apodaca et al ., 2020). Furthermore, benefits from the assimilation of Aeolus observations have also been found in hurricane prediction at NOAA using the regional Hurricane Weather Forecasting system (HWRF, Marinescu et al ., 2022).…”

Filling the Gap of Wind Observations Inside Tropical Cyclones

“…It was shown that the assimilation of Aeolus observations generally improved forecasts of several numerical weather prediction models (NWP) (G. George et al., 2021; Rennie et al., 2021; Laroche & St‐James, 2022). This includes positive impact in the forecast of TC intensity and size (Marinescu et al., 2022), despite Aeolus measurements being made in clear air and thin clouds, and mostly coming from upper troposphere and lower stratosphere. However, it is well known that the tropospheric winds have a crucial role in steering TC tracks (J. E. George & Gray, 1976) and that assimilation of inner core—where most of the rain bands are present—winds is particularly useful for improving forecasts (Feng et al., 2023; Tong et al., 2018).…”