Sciences and Exploration Directorate

Santiago Gassó


Santiago Gassó's Contact Card & Information.
Phone: 301.614.6244
Org Code: 610.1
Mail Code 610.1
Greenbelt, MD 20771

Brief Bio


Dr. Santiago Gassó specializes in observational studies of aerosols, clouds and their interactions using a combination of satellite detectors. He has extensive knowledge on technical fields related to the observation aerosols using laboratory, remote sensing and aircraft sensors as well as operating and modifying aerosol transport models. These activities include research and development aerosol retrieval algorithms (optical range), modeling of aerosol optical properties (including polarization) and discovery of new aerosol and cloud phenomena as well as new approaches to observe them. He has published as lead or co-author in all these subjects in major scientific journals.


Career Summary and Main Projects


He is an University of Washington graduate in geophysics (Atmospheric Science track) with thesis work on in-situ observations of aerosols, their optical properties in relation to remote sensing and evaluation of the first versions of the MODIS (first sensor of NASA's Earth Observing Satellite series) aerosol algorithm. In his post-doctoral work with the Naval Research Laboratory, he acquired aerosol global modeling experience with the design of a (and still currently operational) module to compute optical and radiative aerosol properties in the Navy Aerosol Assimilation Prediction System (NAAPS) model. From 2005 to 2008, he was an aerosol scientist in the NPOESS Preparatory Project science team and he was tasked to evaluate the first versions of the operational aerosol retrieval algorithm. From 2008 to 2107, he was an Ozone Monitoring Instrument (OMI, one of the first hyperspectral sensors with global coverage) science team and a member of the OMI aerosol remote sensing group led by Dr. Omar Torres. During 2009 to 2011, he lead the Aerosol-Ocean Interactions working group, one of the science working groups for the Aerosol, Clouds and Ecosystems (ACE) mission, a proposed NASA mission to fulfill the NRC Decadal Survey requirements. During this time he joined the science team of Japan's Cloud and Aerosol Imager to develop new ways to observe aerosols in the UV (2014-2018). In 2018, he rejoined the S-NPP science team this time as PI scientist and he worked on the development of aerosol retrievals using a combination of near ultraviolet (OMPS-NM sensor) and visible (VIIRS sensor) observations. In the same year, he joined as external science advisor to the algorithm development team of Argentina's SABIA-Mar mission, a moderate spectro-radiometer to be launched in 2024. More recently, he is working in two projects. One is as a science aerosol lead in the development of a new sensor technology for full polarimetry remote sensing (Kerry Meyer and Federico Capasso, NASA and Harvard leads respectively). The second project is within the Dark Target aerosol group (Robert Levy, NASA lead) in GSFC where he is carrying out a critical review and modification of the operational cloud mask scheme in the aerosol algorithms used by MODIS and VIIRS.




 Other Scientific Interests


In addition to the operational aspects of remote sensing retrievals, his research interests include the study of dust at high latitudes. In particular, characterization of its production and long range transport as well as its impacts in biogeochemical and paleo-climate studies. He has carried out for the last 15 years this activity. He has been a collaborator and Co-I in internationally funded projects to survey and monitor dust activity in Patagonia. He made the first dedicated satellite and model studies of dust activity in Patagonia. In 2007, he chaired and organized the Multidisciplinary Workshop on Southern South American Dust held in Puerto Madryn, Argentina, 2007 for which obtained NSF funding and had an attendance 60 participant (~20 international). Between 2010 and 2013, he participated as co-I in a NASA-IDS funded project to characterize dust transport from Alaska glaciers and has been monitoring the area with remote sensing tools since then. During the period 2014-2017, he was part of the High Latitude Dust and Cold Environment Network, a working group supported by The Leverhulme Trust (UK). He has authored or co-authored peer-reviewed journal articles many on the subject of dust transport at high latitudes as characterized by satellite, model and surface observations.


He also developed an interest in studying volcanoes through a discovery he made in 2006. He found that low levels volcanic activity (non-explosive passive degassing activity VEI<2) can be detected in cloudy conditions by studying the change in properties in nearby water clouds. The discovery provides an excellent opportunity for studying aerosol-cloud interactions as well as provides a way to detect volcanic activity in cloudy conditions.


Another subject of interest is the exploration of using measurement of aerosols polarization remotely, specifically by measuring circular polarization (or CP). Currently planned space satellite sensors with polarimetry capabilities will not measure CP. However, there are conditions in the laboratory and in the environment where aerosols can produce circular polarization. Because the scattered nature of the information available on CP in the literature, he wrote in 2022 a first review on the subject of circular polarization of aerosols in relation to satellite applications in order to provide to the science community a guiding document on the subject.


Outreach and Other

Her received leadership awards by NASA's Climate and Radiation Branch in 2006 and 2020.


Additional outreach and networking activates include the participation in the Science Steering Committee of SOLAS (Surface-Ocean Lower Atmosphere Study). SOLAS is an organization dedicated to the promotion, coordination and training of scientists on subjects related to aerosol, gas and cloud exchanges at the marine interface and how these systems interact with each other.


While not currently with a recurrent teaching activity, he has a diverse instructional experience. He has taught in workshops and lectures at undergraduate and graduate level through the years. This included mentoring summer interns, thesis co-adviser as well as invited lecturer of small courses. His most recent teaching activity was carried out during June/2019 when he was invited by the Alfred Wegener Institute (Germany) to be a remote sensing instructor onboard of the ice-breaker Polarstern during their oceanographic summer school. He also taught an online remote sensing tutorial 2022 in the SOLAS summer virtual school and he will carry out a similar SOLAS teaching activity in person next June 202 in Cape Verde, Africa.


Much of these interests are expressed through his social media account (Twitter: @ SanGasso, 3.7K followers) where he regularly posts about his current research and aerosol events around world as seen with remote sensing.


See the ranking of publications:






Research Interests

Remote sensing of absorbing aerosols in the UV-NIR wavelength range

Earth Science: Remote Sensing

In addition to scatter light, airborne particulate matter such as smoke and dust (also known as aerosols) absorb solar energy. This absorbed energy does not reach the surface and the reduction (or redistribution) of this energy can impact photosynthetic processes in both land and ocean ecosystems. In addition, this energy is returned to the environment in the form of heat changing the ambient temperature in the atmospheric column. This results in, for example, cloud dissipation among other effects. Thus, characterization of these aerosols from space is very important because it will enable a better understanding of their impact in the energy balance in the atmosphere as well the processes that modulate cloud formation and ecosystem behavior. The observation absorbing aerosols is most effective in the ultra-violet range of the electromagnetic spectrum. Until recent there were very few space sensors with the UV channels and ground spatial resolution for adequate detection of aerosols from space. One of them was the Ozone Monitoring Instrument on board the NASA’s Aura satellite. As member of the aerosol science team of OMI (lead by Dr. Omar Torres, NASA), I worked to improve existing and try new approaches to observe these aerosols. While this platform was not quite designed for aerosol detection, my experience with OMI really helped me to be ready for the new generation of sensors (TropOMI, TEMPO) that have the right hyperspectral and spatial resolution to observe smoke and dust in ways that have not previously possible to do.

High Latitude Dust in Cold Environments

Earth Science: Aerosols

High Latitude Dust refers to dust generated in mid to high latitudes such as in cold deserts (Patagonia desert in South America) and in the vicinity of glaciers (Alaska, Iceland). The deserts are distinctive in the sense they occur in cold environments, but they do have low precipitation, dry conditions and high winds all necessary conditions for dust production. Satellite images confirm that dust production per event can be abundant. However, the frequency of the events and the abundance of the material produced in these cold environments is much lower than the mid-latitude counterparts. Yet, because their location, they could have a disproportionate and indirect effects in climate. The reason is that most of these sources are located upwind of ocean ecosystems known to be deficient of the micronutrient iron (Fe). Since it is abundant in dust, it is possible that the deposition of Fe may impact the marine ecosystem downwind (specifically via the ingest of nutrients by phytoplankton). Also, the study of high latitude dust in modern times can provide clues of the dynamics of atmospheric transport during previous ice-ages. The reason is that the dust is commonly found in ice cores in both poles, and it is well known the most of it originated from high latitude sources. By understanding the production and transport patterns of modern dust transport, it will be possible to better understand how past climates evolved.

Observations of the Impact of Passive Volcanic Activity on Clouds

Earth Science: Clouds

Volcanic activity from space is most easily detectable when the eruption is powerful enough to send ashes above clouds. However, most of the active volcanoes emit gases, water vapor and ash in rather unenergetic eruptions where the emissions stay at cloud level or do not penetrate through the cloud layer aloft. Consequently, the vast majority of volcanic activity remains undetected unless the volcano is nearby a human settlement or a surface remote sensor. In addition, volcanoes are a source of aerosol and aerosol precursors (such as sulfur dioxide) and they are regularly emitted and mixed with clouds in the environment. Because the injection of these materials into the cloud, the cloud micro- and macro-physical properties of these clouds change accordingly. The extent of this impact is rather unclear. However, passive volcanic activity provides a natural laboratory to study the indirect effect of aerosols in clouds such as the change of the cloud’s reflective and precipitation properties.

Remote Sensing of Marine Biogenic Aerosols

Earth Science: Aerosols

Conventional wisdom about aerosols (i.e particles) in the clear (or remote) marine environment indicates that they are made mostly of sea-salt and sulfate and these components are the dominant components of the total aerosol budget in those environments. And until recently, they were considered the main sources of cloud-forming seeds in vast regions of the open ocean. However, relative recent and numerous in-situ and modeling investigations reveal that aerosols of biogenic origin are important cloud condensation nuclei (CCN), that is, are significant providers of cloud seeding material. Given that clouds in the clear marine environment (think for example, of the Southern Ocean) are the largest reflectors of solar sunlight back to space (thus play a major role in the energy balance of our planet), there is a need to understand the factors that control the formation of these clouds. However, biogenic aerosols are difficult to see from space (low concentrations, high cloudiness) and it is highly uncertain to determine their global distribution, typical concentrations and their impacts in clouds. In fact current remote sensing approaches based on spectral intensity measurements are not adequate for their detection. Thus my interest is to explore alternative approaches (such as using full polarization remote sensing ) that can be potentially used in future platforms or missions.



2024. "Improved simulations of biomass burning aerosol optical properties and lifetimes in the NASA GEOS Model during the ORACLES-I campaign." Atmospheric Chemistry and Physics 24 (7): 4421-4449 [10.5194/acp-24-4421-2024] [Journal Article/Letter]

2023. "An aerosol odyssey: Navigating nutrient flux changes to marine ecosystems." Elem Sci Anth 11 (1): [10.1525/elementa.2023.00037] [Journal Article/Letter]

2023. "Observing ocean ecosystem responses to volcanic ash." Remote Sensing of Environment 296 113749 [] [Journal Article/Letter]

2023. "Health and Safety Effects of Airborne Soil Dust in the Americas and Beyond." Reviews of Geophysics [10.1029/2021rg000763] [Journal Article/Letter]

2022. "Circular polarization in atmospheric aerosols." Atmospheric Chemistry and Physics 22 (20): 13581--13605 [10.5194/acp-22-13581-2022] [Journal Article/Letter]

2022. "Newly identified climatically and environmentally significant high-latitude dust sources." Atmospheric Chemistry and Physics 22 (17): 11889-11930 [10.5194/acp-22-11889-2022] [Journal Article/Letter]

2020. "The Dark Target Algorithm for Observing the Global Aerosol System: Past, Present, and Future." Remote Sensing 12 (18): 2900 [10.3390/rs12182900] [Journal Article/Letter]

2019. "Temporal Characterization of Dust Activity in the Central Patagonia Desert (Years 1964–2017)." Journal of Geophysical Research: Atmospheres 124 (6): 3417-3434 [10.1029/2018jd030209] [Journal Article/Letter]

2019. "Examining links between dust deposition and phytoplankton response using ice cores." Aeolian Research 36 45-60 [10.1016/j.aeolia.2018.11.001] [Journal Article/Letter]

2018. "Assessing the Many Influences of High-Latitude Dust." Eos 99 [10.1029/2018eo090315] [Journal Article/Letter]

2017. "Volcano and Ship Tracks Indicate Excessive Aerosol-Induced Cloud Water Increases in a Climate Model." Geophysical Research Letters 44 (24): 12,492-12,500 [10.1002/2017gl075280] [Journal Article/Letter]

2017. "Simulation of the Ozone Monitoring Instrument aerosol index using the NASA Goddard Earth Observing System aerosol reanalysis products." Atmospheric Measurement Techniques 10 (11): 4121-4134 [10.5194/amt-10-4121-2017] [Journal Article/Letter]

2017. "Multi year aerosol characterization in the tropical Andes and in adjacent Amazonia using AERONET measurements." Atmospheric Environment 166 412 - 432 [] [Journal Article/Letter]

2017. "Atmospheric deposition of glacial iron in the Gulf of Alaska impacted by the position of the Aleutian Low." Geophysical Research Letters 44 (10): 5053-5061 [10.1002/2017gl073565] [Journal Article/Letter]

2016. "High Latitude Dust in the Earth System." Review of Geophysics 54 [10.1002/2016RG000518] [Journal Article/Letter]

2016. "The role of cloud contamination, aerosol layer height and aerosol model in the assessment of the OMI near-UV retrievals over the ocean." Atmospheric Measurements Techniques 9 3031-3052 [10.5194/amt-9-3031-2016] [Journal Article/Letter]

2015. "Spaceborne observations of the lidar ratio of marine aerosols ." Atmos. Chem. Phys. 15 3241-3255 [10.5194/acp-15-3241-2015] [Journal Article/Letter]

2013. "Ground/satellite observations and atmospheric modeling of dust storms originating in the high Puna-Altiplano deserts (South America): Implications for the interpretation of paleo-climatic archives." J. Geophys. Res. Atmos. 118 (9): 3817–3831 [10.1002/jgrd.50036] [Journal Article/Letter]

2011. "Glacial flour dust storms in the Gulf of Alaska: Hydrologic and meteorological controls and their importance as a source of bioavailable iron." Geophysical Research Letters 38 (6): L06602 [10.1029/2010GL046573] [Journal Article/Letter]

2011. "Understanding the transport of Patagonian dust and its influence on marine biological activity in the South Atlantic Ocean." Atmos. Chem. Phys. 11 (6): 2487-2502 [10.5194/acp-11-2487-2011] [Journal Article/Letter]

2010. "Modeling Dust and Soluble Iron Deposition to the South Atlantic Ocean." J. Geophys. Res. 115 15202 [10.1029/2009JD013311] [Journal Article/Letter]

2010. "Interactions between Mineral Dust, Climate, and Ocean Ecosystems." Elements 6 (4): 247-252 [Full Text] [10.2113/gselements.6.4.247] [Journal Article/Letter]

2010. "A combined observational and modeling approach to study modern dust transport from the Patagonia desert to East Antarctica." Atmos. Chem. Phys. 10 (17): 8287-8303 [10.5194/acp-10-8287-2010] [Journal Article/Letter]

2008. "Satellite observations of the impact of weak volcanic activity on marine clouds." J. Geophys. Res. 113 (D14): D14S19 [10.1029/2007JD009106] [Journal Article/Letter]

2007. "Does dust from Patagonia reach the sub-Antarctic Atlantic Ocean?." Geophysical Research Letters 34 (1): L01801 [10.1029/2006GL027693] [Journal Article/Letter]

2007. "Analysis of a potential “solar radiation dose-dimethylsulfide-cloud condensation nuclei” link from globally mapped seasonal correlations." Global Biogeochem. Cycles 21 (2): GB2004 [10.1029/2006GB002787] [Journal Article/Letter]

2006. "Comparisons of remote sensing retrievals and in situ measurements of aerosol fine mode fraction during ACE-Asia." Geophysical Research Letters 33 (5): L05807 [10.1029/2005GL024926] [Journal Article/Letter]

2006. "What controls CCN seasonality in the Southern Ocean? A statistical analysis based on satellite-derived chlorophyll and CCN and model-estimated OH radical and rainfall." Global Biogeochem. Cycles 20 (1): GB1014 [10.1029/2005GB002597] [Journal Article/Letter]

2003. "On the Retrieval of Columnar Aerosol Mass and CCN Concentration by MODIS." J. of Geophys. Res. 108 (D1): 4010 [Full Text] [10.1029/2002JD002382] [Journal Article/Letter]

2001. "Asian dust events of April 1998." Journal of Geophysical Research-Atmospheres 106 (16): 18317-18330 [10.1029/2000JD900788] [Journal Article/Letter]

2000. "Clear-sky closure studies of lower tropospheric aerosol and water vapor during ACE-2 using airborne sunphotometer, airborne in-situ, space-borne, and ground-based measurements." Tellus B 52 (2): 568-593 [10.1034/j.1600-0889.2000.00009.x] [Journal Article/Letter]

1998. "Comparison of columnar aerosol optical properties measured by the MODIS airborne simulator with in situ measurements: A case study." Rem. Sens. Env 66 (2): 138-152 [Full Text] [10.1016/S0034-4257(98)00052-2] [Journal Article/Letter]

1997. "Urban/Industrial Aerosol: Ground-Based Sun/Sky Radiometer and Airborne In Situ Measurements." J. of Geophys. Res. 102 (D14): 16849-16859 [Full Text] [10.1029/96JD01932] [Journal Article/Letter]

1996. "Aerosol Measurements in the Arctic Relevant to Direct and Indirect Radiative Forcing." J. of Geophys. Res. 101 (D18): 23349-23363 [Full Text] [10.1029/96JD02246] [Journal Article/Letter]


2021. "US SOLAS Science Report." [10.1575/1912/27821] [Report]