nasa-gesdisc/es-publications-researchareas huggingface dataset:
The impact of the Amazon–Orinoco River plume on enthalpy flux and air–sea interaction within Caribbean Sea tropical cyclones (2019)

Abstract The influence of the AmazonOrinoco River plume in the Caribbean Sea on latent and sensible heat flux (enthalpy flux) and tropical cyclone (TC) intensity is investigated for Hurricanes Ivan (2004), Emily (2005), Dean (2007), and Felix (2007) using dropwindsonde data, satellite sea surface temperature (SST), and the SMARTS climatology. Relationships among enthalpy fluxes, ocean heat content relative to the 26C isotherm depth (OHC), and SST during storm passage are diagnosed. Results indicate that sea surface cooling in the river plume, a low-OHC region, is comparable to that in the warm eddy region, which has high OHC. An isothermal layer heat budget shows that upper-ocean cooling in the river plume can be explained predominantly by sea-to-air heat flux, rather than by entrainment flux from the thermocline. The latter two findings suggest that relatively large upper-ocean stratification in the plume regime limited entrainment cooling, sustaining SST and enthalpy flux. Inspection of atmospheric variables indicates that deep moderate wind shear is prevalent, and equivalent potential temperature is enhanced over the river plume region for most of these storms. Thus, sustained surface fluxes in this region may have provided warm, moist boundary layer conditions, which may have helped these storms to rapidly intensify even over relatively low-OHC waters and moderate shear. These findings are important because several Caribbean Sea TCs, including these cases, have been underforecast with respect to intensity and/or rapid intensifications, yet minimal upper-ocean observations exist to understand airsea interaction during TCs in the salinity-stratified AmazonOrinoco plume regime.

Research areas: Severe Storms
Influence of Saharan dust on the large‐scale meteorological environment for development of tropical cyclone over North Atlantic Ocean Basin (2020)

The tropical cyclones (TCs) frequently occur in the North Atlantic Ocean Basin, which is adjacent to West Africa, the largest global source of atmospheric dust. However, few studies have conducted systematic observational research of how dust affects the genesis conditions of TCs at large scales which includes sea surface temperature (SST), vorticity, vertical wind shear, and specific humidity. This study focused on the period from June-September in the years 2000 to 2018 to investigate the horizontal and vertical distributions of aerosol optical depth (AOD) (dust) and meteorological parameters. Dust can be transported at 600 hPa upward and is mixed well within the troposphere over land, while it is mainly distributed in the lower troposphere over the ocean. The SST is significantly suppressed by dust due to direct radiation effects, but the atmospheric temperature is warmer at 20-40°W between 700 and 850 hPa. The vertical distributions of temperature and specific humidity are similar. Dust decreases specific humidity in the lower troposphere over the ocean, especially in high AOD regions, but enhances midlevel moisture. Dust heats the lower troposphere and favors the development of convection and positive vorticity at heights of approximately 800-1,000 hPa. The warming effect of dust on the lower atmosphere over land and the nearby oceans results in strengthened West African monsoons and vertical wind shear. Thus, dust suppresses the SST and low-level specific humidities and favors wind shear and positive relative vorticity, which further influence environmental conditions in the TC genesis region.

Research areas: Severe Storms, Atmospheric/Ocean Indicators
The Effect of Typhoon Goni on the Production Characteristics of Coastal Water in Posyet Bay, the Sea of Japan (2021)

The effect caused by the typhoon Goni in the coastal water of Posyet Bay, the Sea of Japan, is considered. In nearshore expeditions, profilograph SBE-19plus was used to measure the hydrological characteristics: water temperature and salinity, as well as the hydrobiological characteristics of the fluorescence of chlorophyll a and dyed dissolved organic matter a week after the passage of the typhoon. To reveal the effect of the typhoon on the ecosystem, the data measured after typhoon passage were compared with the appropriate characteristics obtained in the same season in about the same place a year before, when there was no typhoon. A high correlation was found to exist between chlorophyll a concentration and the input of fresh water from the continent. It was shown that the dyed dissolved organic matter is determined, in addition to the continental export, by autochthonous processes. The problem formulated in the study was solved with the involvement of satellite data, which reflected changes in the ecosystem in large water areas and suggested the conclusion that the changes caused by the typhoon shift the state of the coastal zone toward that of river estuaries.

Research areas: Severe Storms, Ecosystems
First Quasi-Synchronous Hurricane Quad-Polarization Observations by C-Band Radar Constellation Mission and RADARSAT-2 (2022)

This is the first presentation of quasi-synchronous spaceborne synthetic aperture radar (SAR) high-resolution images acquired from C-band Radar Constellation Mission (RCM) and RADARSAT-2 consisting of quad-polarization (HH + HV + VH + VV) wide-swath observations of Hurricane Epsilon. These measurements clearly show that the denoised HV- and VH-polarized normalized radar cross sections (NRCSs) have great consistency. NRCS values at HV- and VH-polarizations are more sensitive to wind speeds and less sensitive to incidence angles or wind directions than those at HH and VV for hurricane force winds. For large incidence angles and high wind speeds, the sensitivity of HH-polarized NRCS to wind speed is higher than that of VV. HH- and VV-polarized NRCSs gradually lose wind direction dependency at high winds. It is notable that the time interval between the two SAR acquisitions is only 3 min. This allows for a direct comparison of HV- and VH-polarized images to investigate the variations in high-resolution backscattering within the hurricane vortex, thereby revealing the most dynamical areas. An asymmetric dynamic is observed around the eye of Hurricane Epsilon, based on positive and negative differences (VHHV) in the western and eastern parts of the eye. The impacts of rain on quad-polarized NRCS are also examined using collocated rain rates from the Global Precipitation Mission (GPM) and wind speeds from the Soil Moisture Active Passive (SMAP). Significant rain-induced NRCS attenuations are about 1.7 dB for HH and VV, and 2.2 dB for HV and VH, when the rain rate is 20 mm/h. These attenuations are associated with rain-induced turbulence and atmospheric absorption. This work shows that the collocated RCM and RADARSAT-2 hurricane observations provide a unique analysis of synoptic and joint C-band measurements of the ocean surface in quad-polarization; this is noteworthy in view of preparations for the next generation of dual-polarization scatterometer (SCA) onboard second-generation meteorological operational satellite program (MetOp-SG).

Research areas: Severe Storms
Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations (2018)

Abstract. Aerosolcloud interactions are a major source of uncertainty in inferring the climate sensitivity from the observational record of temperature. The adjustment of clouds to aerosol is a poorly constrained aspect of these aerosolcloud interactions. Here, we examine the response of midlatitude cyclone cloud properties to a change in cloud droplet number concentration (CDNC). Idealized experiments in high-resolution, convection-permitting global aquaplanet simulations with constant CDNC are compared to 13 years of remote-sensing observations. Observations and idealized aquaplanet simulations agree that increased warm conveyor belt (WCB) moisture flux into cyclones is consistent with higher cyclone liquid water path (CLWP). When CDNC is increased a larger LWP is needed to give the same rain rate. The LWP adjusts to allow the rain rate to be equal to the moisture flux into the cyclone along the WCB. This results in an increased CLWP for higher CDNC at a fixed WCB moisture flux in both observations and simulations. If observed cyclones in the top and bottom tercile of CDNC are contrasted it is found that they have not only higher CLWP but also cloud cover and albedo. The difference in cyclone albedo between the cyclones in the top and bottom third of CDNC is observed by CERES to be between 0.018 and 0.032, which is consistent with a 4.68.3 Wm2 in-cyclone enhancement in upwelling shortwave when scaled by annual-mean insolation. Based on a regression model to observed cyclone properties, roughly 60 % of the observed variability in CLWP can be explained by CDNC and WCB moisture flux.

Research areas: Severe Storms
Tropical cyclone characteristics associated with extreme precipitation in the northern Philippines (2021)

The Philippines is exposed to tropical cyclones (TCs) throughout the year due to its location in the western North Pacific. While these TCs provide much-needed precipitation for the country's hydrological cycle, extreme precipitation from TCs may also cause damaging hazards such as floods and landslides. This study examines the relationship between TC extreme precipitation and TC characteristics, including movement speed, intensity and season, for westward-moving TCs crossing Luzon, northern Philippines. We measure extreme precipitation by the weighted precipitation exceedance (WPE), calculated against a 95th percentile threshold, which considers both the magnitude and spatial extent of TC-related extreme precipitation. WPE has a significant, moderate positive relationship with TC intensity with a non-significant, weak negative relationship with movement speed. When TCs are classified by intensity 1 day before landfall (or pre-landfall), Typhoons (1-min maximum sustained wind speed ≥64 knots) tend to yield higher WPE than non-Typhoons (&lt;64 knots). On the other hand, when TCs are classified by pre-landfall speed, slow TCs (movement speed &lt;11.38 knots) tend to yield higher WPE than fast TCs (movement speed ≥11.38 knots). However, the relationship between pre-landfall TC intensity and WPE is more pronounced during June-September while there is no significant difference between the WPE of the southwest monsoon (June-September) and northeast monsoon (October-December) seasons. These results suggest that it is important to consider the pre-landfall cyclone movement speed, intensity and season to anticipate extreme precipitation of incoming TCs. A decision table considering these factors is devised to aid in TC extreme precipitation forecasting.

Research areas: Severe Storms, Atmospheric/Ocean Indicators
Wet-to-dry climate shift of the Sichuan Basin during 1961-2010 (2021)

The autumn precipitation over the Sichuan Basin (APSB) experienced a significant wet-to-dry shift around the mid-1980s during the 1961-2010 period. Thus, the dataset is divided into two subperiods, 1961-1985 (P1) and 1986-2010 (P2), which are denoted as the wet period and dry period, respectively. The possible mechanisms accounting for the wet-to-dry shift in the APSB are investigated using both observational data and a baroclinic atmospheric model. Analysis shows that the sea surface temperature (SST) in the tropical Indian-western Pacific (TIWP) regions displays continuous warming during the period under examination, which may intensify the ascent motion over the warm pool and favor the descent motion over the Sichuan Basin. Meanwhile, the Gill-type atmospheric response to anomalous TIWP warm SST is accompanied by anomalous northerly winds prevailing over central and Southwest China. Both the intensified descent motion and anomalous northerly winds over central and Southwest China favor the switch to dry conditions in the APSB. Further analysis shows that the decadal changes in the North Atlantic SST lead to an atmospheric wave pattern prevailing over the extratropical Eurasian continent. An anomalous cyclone over central-eastern Eurasia, which is one component of the wave pattern, is accompanied by significant northerly winds penetrating southward to central China. These northerly winds can cause more-than-normal snow cover around Lake Baikal, which may in turn modulate the atmospheric circulation through positive feedback and therefore result in intensified northerly winds, favorable for the switch to the anomalous dry state of the APSB.

Research areas: Atmospheric/Ocean Indicators
Precipitation stable isotopic signatures of tropical cyclones in Metropolitan Manila, Philippines, show significant negative isotopic excursions (2022)

Abstract. Tropical cyclones have devastating impacts on the environment, economies, and societies and may intensify in the coming decades due to climate change. Stable water isotopes serve as tracers of the hydrological cycle, as isotope fractionation processes leave distinct precipitation isotopic signatures. Here we present a record of daily precipitation isotope measurements from March 2014 to October 2015 for Metropolitan Manila, a first-of-a-kind dataset for the Philippines and Southeast Asia. We show that precipitation isotopic variation at our study site is closely related to tropical cyclones. The most negative shift in 18O values (13.84 ) leading to a clear isotopic signal was caused by Typhoon Rammasun, which directly hit Metropolitan Manila. The average 18O value of precipitation associated with tropical cyclones is 10.24 , whereas the mean isotopic value for rainfall associated with non-cyclone events is 5.29 . Further, the closer the storm track is to the sampling site, the more negative the isotopic values are, indicating that in situ isotope measurements can provide a direct linkage between isotopes and typhoon activities in the Philippines.

Research areas: Severe Storms
Sensitivity of simulating Typhoon Haiyan (2013) using WRF: the role of cumulus convection, surface flux parameterizations, spectral nudging, and initial and boundary conditions (2022)

Abstract. Typhoon (TY) Haiyan was one of the most intense and highly
destructive tropical cyclones (TCs) to affect the Philippines. As such, it
is regarded as a baseline for extreme TC hazards. Improving the simulation
of such TCs will not only improve the forecasting of intense TCs but will
also be essential in understanding the potential sensitivity of future
intense TCs with climate change. In this study, we investigate the effects
of model configuration in simulating TY Haiyan using the Weather Research
Forecasting (WRF) Model. Sensitivity experiments were conducted by
systematically altering the choice of cumulus schemes, surface flux
options,
and spectral nudging. In addition to using the European Centre for
Medium-Range Weather Forecasts Reanalysis fifth-generation (ERA5) single
high-resolution realization as initial and boundary conditions, we also
used 4
of the 10 lower-resolution ERA5 data assimilation system (EDA) ensemble
members as initial and boundary conditions. Results indicate a high level
of
sensitivity to cumulus schemes, with a trade-off between using
KainFritsch and Tiedtke schemes that have not been mentioned in past
studies of TCs in the Philippines. The Tiedtke scheme simulates the track
better (with a lower mean direct positional error, DPE, of 33 km), while
the KainFritsch scheme produces stronger intensities (by 15 hPa minimum
sea level pressure). Spectral nudging also resulted in a reduction in the
mean DPE by 20 km, and varying the surface flux options resulted in the
improvement of the simulated maximum sustained winds by up to
10 m s1. Simulations using the EDA members initial and boundary
conditions revealed low sensitivity to the initial and boundary conditions,
having less spread than the simulations using different parameterization
schemes. We highlight the advantage of using an ensemble of cumulus
parameterizations to take into account the uncertainty in the track and
intensity of simulating intense tropical cyclones.

Research areas: Severe Storms
Zircon as a recorder of contrasting magma recharge and eruptive recurrence patterns (2021)

Contrasting Late PleistoceneHolocene eruptive behavior observed for Mt. Hasan and Mt. Erciyes, two neighboring stratovolcanic complexes in Central Anatolia, Turkey, poses general questions on the size and nature of magma systems underlying active volcanoes. Here, we complement UThPb zircon rim and interior crystallization ages for >1000 crystals from these volcanoes with trace element analyses on the same spots to unravel their magmatic histories. Thermochemical modeling of zircon crystallization is applied to quantify contrasting magma recharge and storage regimes. Both Mt. Hasan and Mt. Erciyes are characterized by protracted magmatic and volcanic activity since the Middle Pleistocene that is evident from individual crystals and crystal populations. However, zircon records contrasting thermochemical evolutions for both systems: Mt. Hasan with a history of recurrent eruptions throughout the Late Pleistocene exhibits comparatively narrow ranges of Ti-in-zircon crystallization temperatures and differentiation indices such as Zr/Hf ratios as well as Eu anomalies (Eu/Eu*) over the last ca. 300 ka. On the contrary, these parameters fluctuate over broader ranges for Mt. Erciyes, where relatively primitive zircon interiors nucleated during two major eruptive activity phases at ca. 10585 and ca. 9 ka, whereas zircon rims evolved to more differentiated compositions during the protracted eruptive lull in between. The contrasting zircon record is interpreted to mirror a protracted thermochemical steady-state of the Mt. Hasan magma system, but fluctuating conditions in Mt. Erciyes due to recharge rate variations. Zircon ages are modeled with integrated magma recharge rates of 10.5 km3/ka for Mt. Hasan, but only 0.1 km3/ka for Mt. Erciyes, indicating warm magma storage under eruptible conditions for Mt. Hasan, but cold magma storage below the rheological lockup temperature for Mt. Erciyes. The smaller volume of the Mt. Erciyes subsurface plumbing system contrasts with its larger edifice volume, suggesting that the volcano has reached a waning stage where episodically intensified magma recharge can trigger violent eruptions. The early Holocene resurgence of Mt. Erciyes may be in response to glacial unloading, whereas the peak-stage Mt. Hasan system may be less responsive to changes in magma recharge due to thermal buffering by a voluminous magma reservoir.

Research areas: Volcanic Eruptions
Changes in stratospheric aerosol extinction coefficient after the 2018 (2021)

Abstract. Stratospheric aerosols are an important component of the climate system. They not only change the radiative budget of the Earth but also play an
essential role in ozone depletion. These impacts are particularly noticeable after volcanic eruptions when SO2 injected with the eruption reaches the stratosphere, oxidizes, and forms stratospheric aerosol. There have been several studies in which a volcanic eruption plume and the associated radiative forcing were analyzed using climate models and/or data from satellite measurements. However, few have compared vertically and temporally resolved volcanic plumes using both measured and modeled data. In this paper, we compared changes in the stratospheric aerosol loading after the 2018 Ambae eruption observed by satellite remote sensing measurements and simulated by a global aerosol model. We use vertical profiles of the aerosol extinction coefficient at 869 nm retrieved at the Institute of Environmental Physics (IUP) in Bremen from OMPS-LP (Ozone Mapping and Profiling Suite  Limb Profiler) observations. Here, we present the retrieval algorithm and a comparison of the obtained profiles with those from SAGE III/ISS (Stratospheric Aerosol and Gas Experiment III on board the International Space Station). The observed differences are within 25 % for most latitude bins, which indicates a reasonable quality of the retrieved limb aerosol extinction product. The volcanic plume evolution is investigated using both monthly mean aerosol extinction coefficients and 10 d averaged data. The measurement results were compared with the model output from MAECHAM5-HAM (ECHAM for short). In order to simulate the eruption accurately, we use SO2 injection estimates from OMPS and OMI (Ozone Monitoring Instrument) for the first phase of eruption and the TROPOspheric Monitoring Instrument (TROPOMI) for the second phase. Generally, the agreement between the vertical and geographical distribution of the aerosol extinction coefficient from OMPS-LP and ECHAM is quite remarkable, in particular, for the second phase. We attribute the good consistency between the model and the measurements to the precise estimation of injected SO2 mass and height, as well as to the nudging to ECMWF ERA5 reanalysis data. Additionally, we compared the radiative forcing (RF) caused by the increase in the aerosol loading in the stratosphere after the eruption. After accounting for the uncertainties from different RF calculation methods, the RFs from ECHAM and OMPS-LP agree quite well. We estimate the tropical (20 N to 20 S) RF from the second Ambae eruption to be about 0.13 W m2.

Research areas: Volcanic Eruptions
Volcanic eruption eye-witnessed and recorded by prehistoric humans (2019)

Human footprints in hydrovolcanic ash near Cakallar volcano (Kula, Western Turkey) were discovered in 1968. A nearby pictograph interpreted as depicting Cakallar volcano would define it as the oldest site where humans demonstrably eye-witnessed a volcanic eruption and possibly artistically recorded it. Despite Cakallar's volcanological and cultural importance, its eruption age has remained controversial. Here, two independent dating methods, cosmogenic 36Cl and combined U-Pb and (U-Th)/He zircon (ZDD) geochronology, yielded the first internally consistent eruption ages controlled by detailed volcanostratigraphic mapping. Concordant 36Cl ages of 4.7  0.6 ka (errors 1) were obtained for a cone-breaching lava flow. ZDD ages for crustal xenoliths from scoria deposits directly overlying the footprints yielded an age of 4.7  0.7 ka. This firmly places the Cakallar eruption and prehistoric human footprints, and plausibly the rock art, into the Bronze Age, reinforcing the notion that prehistoric artwork recorded natural events.

Research areas: Volcanic Eruptions