Mark Schoeberl - Academia.edu (original) (raw)
Papers by Mark Schoeberl
Atmospheric Chemistry and Physics, Jul 10, 2009
Estimates of the radiative forcing due to anthropogenically-produced tropospheric O 3 are derived... more Estimates of the radiative forcing due to anthropogenically-produced tropospheric O 3 are derived primarily from models. Here, we use tropospheric ozone and cloud data from several instruments in the A-train constellation of satellites as well as information from the GEOS-5 Data Assimilation System to accurately estimate the radiative effect of tropospheric O 3 for January and July 2005. Since we cannot distinguish between natural and anthropogenic sources with the satellite data, our derived radiative effect reflects the unadjusted (instantaneous) effect of the total tropospheric O 3 rather than the anthropogenic component. We improve upon previous estimates of tropospheric ozone mixing ratios from a residual approach using the NASA Earth Observing System (EOS) Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) by incorporating cloud pressure information from OMI. We focus specifically on the magnitude and spatial structure of the cloud effect on both the short-and long-wave radiative budget. The estimates presented here can be used to evaluate the various aspects of model-generated radiative forcing. For example, our derived cloud impact is to reduce the radiative effect of tropospheric ozone by ∼16%. This is centered within the published range of model-produced cloud effect on unadjusted ozone radiative forcing.
The Sensor Web concept emerged as the number of Earth Science Satellites began to increase in the... more The Sensor Web concept emerged as the number of Earth Science Satellites began to increase in the recent years. The idea, part of a vision for the future of earth science, was that the sensor systems would be linked in an active way to provide improved forecast capability. This means that a system that is nearly autonomous would need to be developed to allow the satellites to re-target and deploy assets for particular phenomena or provide on board processing for real time data. This talk will describe several elements of the sensor web.
Gynecologic Oncology, 2007
The objective of this study is to develop a physical model of the behavior of beta-hCG following ... more The objective of this study is to develop a physical model of the behavior of beta-hCG following the complete evacuation of a hydatidiform mole. Because hCG is an excellent marker for continued trophoblastic activity, the model can be used for early detection of persistent sites. The model was developed from analysis of the post surgical hCG decrease in a patient with Stage III gestational trophoblastic neoplasia. As found in previous molar pregnancy studies, hCG follows a log-linear decrease after resolution. In contrast to those studies, however, we assume that the decrease can be explained by the dilution of the residual hCG from two different tissue reservoirs, a tissue reservoir with a half-life of approximately 4 days and a reservoir with a longer half-life, in this case approximately 18 days. Simple dilution of two tissue reservoirs explains behavior of hCG following tumor removal. The model also explains the hCG decrease in a larger study of Japanese and Dutch women following the evacuation of uneventful hydatidiform moles. Following an initial rapid drop in hCG after resolution of the mole, the patient should experience a slower drop associated with the dilution of residual hCG in the deep tissue reservoir. This is normal. The physical model suggests that even earlier detection of chemotherapy resistant persistent trophoblastic disease is possible if the patient's decrease in hCG is slower than a log-linear fit to the patient's previous data. The results also suggest an alternative approach to processing patient statistics in analysis of carcinomas with large variations in the tumor marker concentrations.
Domain filling, forward trajectory calculations are used to examine the global dehydration proces... more Domain filling, forward trajectory calculations are used to examine the global dehydration processes that control stratospheric water vapor. As with most Lagrangian models of this type, water vapor is instantaneously removed from the parcel to keep the relative humidity (RH) with respect to ice from exceeding saturation or a specified super-saturation value. We also test a simple parameterization of stratospheric convective moistening through ice lofting and the effect of gravity waves as a mechanism that can augment dehydration. Comparing diabatic and kinematic trajectories driven by the MERRA reanalysis, we find that, unlike the results from Liu et al. (2010), the additional transport due to the vertical velocity "noise" in the kinematic calculation creates too dry a stratosphere and a too diffuse a water-vapor tape recorder signal compared observations. We also show that the kinematically driven parcels are more likely to encounter the coldest tropopause temperatures than the diabatic trajectories. The diabatic simulations produce stratospheric water vapor mixing ratios close to that observed by Aura's Microwave Limb Sounder and are consistent with the MERRA tropical tropopause temperature biases. Convective moistening, which will increase stratospheric HDO, also increases stratospheric water vapor while the addition of parameterized gravity waves does the opposite. We find that while the Tropical West Pacific is the dominant dehydration location, but dehydration over Tropical South America is also important. Antarctica makes a small contribution to the overall stratospheric water vapor budget as well by releasing very dry air into the Southern Hemisphere stratosphere following the break up of the winter vortex.
Geophysical Research Letters, 2016
Climate models predict that tropical lower stratospheric humidity will increase as the climate wa... more Climate models predict that tropical lower stratospheric humidity will increase as the climate warms. We examine this trend in two state‐of‐the‐art chemistry‐climate models. Under high greenhouse gas emissions scenarios, the stratospheric entry value of water vapor increases by ~1 ppmv over the 21st century in both models. We show with trajectory runs driven by model meteorological fields that the warming tropical tropopause layer (TTL) explains 50–80% of this increase. The remainder is a consequence of trends in evaporation of ice convectively lofted into the TTL and lower stratosphere. Our results further show that within the models we examined, ice lofting is primarily important on long time scales; on interannual time scales, TTL temperature variations explain most of the variations in lower stratospheric humidity. Assessing the ability of models to realistically represent ice lofting processes should be a high priority in the modeling community.
Journal of Geophysical Research: Atmospheres, 2015
Earth and Space Science, 2016
Using the Modern Era Retrospective‐Analysis for Research and Applications (MERRA) and MERRA‐2 rea... more Using the Modern Era Retrospective‐Analysis for Research and Applications (MERRA) and MERRA‐2 reanalysis winds, temperatures, and anvil cloud ice, we explore the impact of varying the cloud nucleation threshold relative humidity (RH) and high‐frequency gravity waves on stratospheric water vapor (H2O) and upper tropical tropopause cloud fraction (TCF). Our model results are compared to 2008/2009 winter TCF derived from Cloud‐Aerosol Lidar with Orthogonal Polarization and H2O observations from the Microwave Limb Sounder (MLS). The RH threshold affects both model H2O and TCF, while high‐frequency gravity waves mostly impact TCF. Adjusting the nucleation RH and the amplitude of high‐frequency gravity waves allows us to tune the model to observations. Reasonable observational agreement is obtained with a nucleation threshold between 130% and 150% RH consistent with airborne observations. For the MERRA reanalysis, we lower the tropopause temperature by 0.5 K roughly consistent with GPS ra...
Earth and Space Science, 2015
We use a 1‐D cloud model run using a prescribed temperature field to investigate the role of grav... more We use a 1‐D cloud model run using a prescribed temperature field to investigate the role of gravity waves in dehydration in the tropical tropopause layer (TTL). We find that gravity waves play an important role in the TTL dehydration process beyond just lowering the minimum temperature experienced by the air parcels. We show that the more rapid cooling in the presence of gravity waves significantly increases the abundance ice crystals. This increase in ice crystal concentration causes a more rapid depletion of vapor in excess of saturation, and the resultant cloud dehydration efficiency is increased. Using a spectrum of gravity waves, we generate ice particle statistics that are in good agreement with observations. We also find that the gravity waves increase cloudiness. Our results show that cloud physics and gravity wave temperature fluctuations cannot be neglected in simulating the TTL physics. In fact, it appears that short‐period waves may be an essential component of the TTL ...
Journal of Geophysical Research: Atmospheres, 2014
We examine variations in water vapor in air entering the stratosphere through the tropical tropop... more We examine variations in water vapor in air entering the stratosphere through the tropical tropopause layer (TTL) over the past three decades in satellite data and in a trajectory model. Most of the variance can be explained by three processes that affect the TTL: the quasi‐biennial oscillation, the strength of the Brewer‐Dobson circulation, and the temperature of the tropical troposphere. When these factors act in phase, significant variations in water entering the stratosphere are possible. We also find that volcanic eruptions, which inject aerosol into the TTL, affect the amount of water entering the stratosphere. While there is clear decadal variability in the data and models, we find little evidence for a long‐term trend in water entering the stratosphere through the TTL over the past 3 decades.
ABSTRACT Much progress has been made in trying to create satellite products for tracking the impo... more ABSTRACT Much progress has been made in trying to create satellite products for tracking the important pollutants ozone and NO2 in the troposphere. Yet, in mid-latitude regions where meteorological interactions with pollutants are complex, accuracy can be difficult to achieve, largely due to rapid changes and persistent layering of some constituents. Comparisons of TTOR ozone and satellite NO2 with ground-truth are presented, mostly from the mid-Atlantic coastal area. Examples of the complexity of retrieving tropospheric ozone column amounts are illustrated with soundings and aircraft profiles from campaigns in the past several years, including the July 2011 DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality).
In both the tropical and extratropical regions there are a large number of dynamical problems whi... more In both the tropical and extratropical regions there are a large number of dynamical problems which can be addressed by mesosphere-stratosphere-troposphere (MST) radars. The distinct advantage the MST radar has over rocket observations is continuous data acquisition. Without a doubt, the time-space spectrum of the mesospheric flow field is rich in high frequency motions associated with gravity waves rather than turbulent (random) fluctuations, and these events are particularly amenable to analysis with continuous data sets. In addition to the high frequency motions these are longer period fluctuations in the upper stratosphere and mesosphere wind fields which, combined with temperature fields derived from satellite data or lidars, can greatly enhance our knowledge of the upper atmosphere.
Journal of the Atmospheric Sciences, 1989
Atmospheric Chemistry and Physics, Jul 10, 2009
Estimates of the radiative forcing due to anthropogenically-produced tropospheric O 3 are derived... more Estimates of the radiative forcing due to anthropogenically-produced tropospheric O 3 are derived primarily from models. Here, we use tropospheric ozone and cloud data from several instruments in the A-train constellation of satellites as well as information from the GEOS-5 Data Assimilation System to accurately estimate the radiative effect of tropospheric O 3 for January and July 2005. Since we cannot distinguish between natural and anthropogenic sources with the satellite data, our derived radiative effect reflects the unadjusted (instantaneous) effect of the total tropospheric O 3 rather than the anthropogenic component. We improve upon previous estimates of tropospheric ozone mixing ratios from a residual approach using the NASA Earth Observing System (EOS) Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) by incorporating cloud pressure information from OMI. We focus specifically on the magnitude and spatial structure of the cloud effect on both the short-and long-wave radiative budget. The estimates presented here can be used to evaluate the various aspects of model-generated radiative forcing. For example, our derived cloud impact is to reduce the radiative effect of tropospheric ozone by ∼16%. This is centered within the published range of model-produced cloud effect on unadjusted ozone radiative forcing.
The Sensor Web concept emerged as the number of Earth Science Satellites began to increase in the... more The Sensor Web concept emerged as the number of Earth Science Satellites began to increase in the recent years. The idea, part of a vision for the future of earth science, was that the sensor systems would be linked in an active way to provide improved forecast capability. This means that a system that is nearly autonomous would need to be developed to allow the satellites to re-target and deploy assets for particular phenomena or provide on board processing for real time data. This talk will describe several elements of the sensor web.
Gynecologic Oncology, 2007
The objective of this study is to develop a physical model of the behavior of beta-hCG following ... more The objective of this study is to develop a physical model of the behavior of beta-hCG following the complete evacuation of a hydatidiform mole. Because hCG is an excellent marker for continued trophoblastic activity, the model can be used for early detection of persistent sites. The model was developed from analysis of the post surgical hCG decrease in a patient with Stage III gestational trophoblastic neoplasia. As found in previous molar pregnancy studies, hCG follows a log-linear decrease after resolution. In contrast to those studies, however, we assume that the decrease can be explained by the dilution of the residual hCG from two different tissue reservoirs, a tissue reservoir with a half-life of approximately 4 days and a reservoir with a longer half-life, in this case approximately 18 days. Simple dilution of two tissue reservoirs explains behavior of hCG following tumor removal. The model also explains the hCG decrease in a larger study of Japanese and Dutch women following the evacuation of uneventful hydatidiform moles. Following an initial rapid drop in hCG after resolution of the mole, the patient should experience a slower drop associated with the dilution of residual hCG in the deep tissue reservoir. This is normal. The physical model suggests that even earlier detection of chemotherapy resistant persistent trophoblastic disease is possible if the patient's decrease in hCG is slower than a log-linear fit to the patient's previous data. The results also suggest an alternative approach to processing patient statistics in analysis of carcinomas with large variations in the tumor marker concentrations.
Domain filling, forward trajectory calculations are used to examine the global dehydration proces... more Domain filling, forward trajectory calculations are used to examine the global dehydration processes that control stratospheric water vapor. As with most Lagrangian models of this type, water vapor is instantaneously removed from the parcel to keep the relative humidity (RH) with respect to ice from exceeding saturation or a specified super-saturation value. We also test a simple parameterization of stratospheric convective moistening through ice lofting and the effect of gravity waves as a mechanism that can augment dehydration. Comparing diabatic and kinematic trajectories driven by the MERRA reanalysis, we find that, unlike the results from Liu et al. (2010), the additional transport due to the vertical velocity "noise" in the kinematic calculation creates too dry a stratosphere and a too diffuse a water-vapor tape recorder signal compared observations. We also show that the kinematically driven parcels are more likely to encounter the coldest tropopause temperatures than the diabatic trajectories. The diabatic simulations produce stratospheric water vapor mixing ratios close to that observed by Aura's Microwave Limb Sounder and are consistent with the MERRA tropical tropopause temperature biases. Convective moistening, which will increase stratospheric HDO, also increases stratospheric water vapor while the addition of parameterized gravity waves does the opposite. We find that while the Tropical West Pacific is the dominant dehydration location, but dehydration over Tropical South America is also important. Antarctica makes a small contribution to the overall stratospheric water vapor budget as well by releasing very dry air into the Southern Hemisphere stratosphere following the break up of the winter vortex.
Geophysical Research Letters, 2016
Climate models predict that tropical lower stratospheric humidity will increase as the climate wa... more Climate models predict that tropical lower stratospheric humidity will increase as the climate warms. We examine this trend in two state‐of‐the‐art chemistry‐climate models. Under high greenhouse gas emissions scenarios, the stratospheric entry value of water vapor increases by ~1 ppmv over the 21st century in both models. We show with trajectory runs driven by model meteorological fields that the warming tropical tropopause layer (TTL) explains 50–80% of this increase. The remainder is a consequence of trends in evaporation of ice convectively lofted into the TTL and lower stratosphere. Our results further show that within the models we examined, ice lofting is primarily important on long time scales; on interannual time scales, TTL temperature variations explain most of the variations in lower stratospheric humidity. Assessing the ability of models to realistically represent ice lofting processes should be a high priority in the modeling community.
Journal of Geophysical Research: Atmospheres, 2015
Earth and Space Science, 2016
Using the Modern Era Retrospective‐Analysis for Research and Applications (MERRA) and MERRA‐2 rea... more Using the Modern Era Retrospective‐Analysis for Research and Applications (MERRA) and MERRA‐2 reanalysis winds, temperatures, and anvil cloud ice, we explore the impact of varying the cloud nucleation threshold relative humidity (RH) and high‐frequency gravity waves on stratospheric water vapor (H2O) and upper tropical tropopause cloud fraction (TCF). Our model results are compared to 2008/2009 winter TCF derived from Cloud‐Aerosol Lidar with Orthogonal Polarization and H2O observations from the Microwave Limb Sounder (MLS). The RH threshold affects both model H2O and TCF, while high‐frequency gravity waves mostly impact TCF. Adjusting the nucleation RH and the amplitude of high‐frequency gravity waves allows us to tune the model to observations. Reasonable observational agreement is obtained with a nucleation threshold between 130% and 150% RH consistent with airborne observations. For the MERRA reanalysis, we lower the tropopause temperature by 0.5 K roughly consistent with GPS ra...
Earth and Space Science, 2015
We use a 1‐D cloud model run using a prescribed temperature field to investigate the role of grav... more We use a 1‐D cloud model run using a prescribed temperature field to investigate the role of gravity waves in dehydration in the tropical tropopause layer (TTL). We find that gravity waves play an important role in the TTL dehydration process beyond just lowering the minimum temperature experienced by the air parcels. We show that the more rapid cooling in the presence of gravity waves significantly increases the abundance ice crystals. This increase in ice crystal concentration causes a more rapid depletion of vapor in excess of saturation, and the resultant cloud dehydration efficiency is increased. Using a spectrum of gravity waves, we generate ice particle statistics that are in good agreement with observations. We also find that the gravity waves increase cloudiness. Our results show that cloud physics and gravity wave temperature fluctuations cannot be neglected in simulating the TTL physics. In fact, it appears that short‐period waves may be an essential component of the TTL ...
Journal of Geophysical Research: Atmospheres, 2014
We examine variations in water vapor in air entering the stratosphere through the tropical tropop... more We examine variations in water vapor in air entering the stratosphere through the tropical tropopause layer (TTL) over the past three decades in satellite data and in a trajectory model. Most of the variance can be explained by three processes that affect the TTL: the quasi‐biennial oscillation, the strength of the Brewer‐Dobson circulation, and the temperature of the tropical troposphere. When these factors act in phase, significant variations in water entering the stratosphere are possible. We also find that volcanic eruptions, which inject aerosol into the TTL, affect the amount of water entering the stratosphere. While there is clear decadal variability in the data and models, we find little evidence for a long‐term trend in water entering the stratosphere through the TTL over the past 3 decades.
ABSTRACT Much progress has been made in trying to create satellite products for tracking the impo... more ABSTRACT Much progress has been made in trying to create satellite products for tracking the important pollutants ozone and NO2 in the troposphere. Yet, in mid-latitude regions where meteorological interactions with pollutants are complex, accuracy can be difficult to achieve, largely due to rapid changes and persistent layering of some constituents. Comparisons of TTOR ozone and satellite NO2 with ground-truth are presented, mostly from the mid-Atlantic coastal area. Examples of the complexity of retrieving tropospheric ozone column amounts are illustrated with soundings and aircraft profiles from campaigns in the past several years, including the July 2011 DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality).
In both the tropical and extratropical regions there are a large number of dynamical problems whi... more In both the tropical and extratropical regions there are a large number of dynamical problems which can be addressed by mesosphere-stratosphere-troposphere (MST) radars. The distinct advantage the MST radar has over rocket observations is continuous data acquisition. Without a doubt, the time-space spectrum of the mesospheric flow field is rich in high frequency motions associated with gravity waves rather than turbulent (random) fluctuations, and these events are particularly amenable to analysis with continuous data sets. In addition to the high frequency motions these are longer period fluctuations in the upper stratosphere and mesosphere wind fields which, combined with temperature fields derived from satellite data or lidars, can greatly enhance our knowledge of the upper atmosphere.
Journal of the Atmospheric Sciences, 1989