scholarly journals The Global Distribution of Supersaturation in the Upper Troposphere from the Atmospheric Infrared Sounder

2006 ◽  
Vol 19 (23) ◽  
pp. 6089-6103 ◽  
Author(s):  
Andrew Gettelman ◽  
Eric J. Fetzer ◽  
Annmarie Eldering ◽  
Fredrick W. Irion
Keyword(s):  
Relative Humidity ◽  
Storm Track ◽  
Satellite Observations ◽  
Atmospheric Infrared Sounder ◽  
Temperature Variance ◽  
Upper Troposphere ◽  
Tropical Tropopause ◽  
Global Coverage ◽  
Higher Temperature

Abstract Satellite data from the Atmospheric Infrared Sounder (AIRS) is analyzed to examine regions of the upper troposphere that are supersaturated: where the relative humidity (RH) is greater than 100%. AIRS data compare well to other in situ and satellite observations of RH and provide daily global coverage up to 200 hPa, though satellite observations of supersaturation are highly uncertain. The climatology of supersaturation is analyzed statistically to understand where supersaturation occurs and how frequently. Supersaturation occurs in humid regions of the upper tropical tropopause near convection 10%–20% of the time at 200 hPa. Supersaturation is very frequent in the extratropical upper troposphere, occurring 20%–40% of the time, and over 50% of the time in storm track regions below the tropopause. The annual cycle of supersaturation is consistent for the ∼2.5 yr of data analyzed. More supersaturation is seen in the Southern Hemisphere midlatitudes, which may be attributed to higher temperature variance.

scholarly journals Seasonal stratospheric intrusion of ozone in the upper troposphere over India

2010 ◽  
Vol 28 (11) ◽  
pp. 2149-2159 ◽  
Author(s):  
S. Fadnavis ◽  
T. Chakraborty ◽  
G. Beig
Keyword(s):  
Relative Humidity ◽  
Satellite Observations ◽  
Vertical Profiles ◽  
Mixing Ratio ◽  
Regular Feature ◽  
Upper Troposphere ◽  
Chemical Tracers ◽  
Earth Observing System ◽  
Stratospheric Intrusion ◽  
Downward Propagation

Abstract. The Model for Ozone and Related chemical Tracers-2 (MOZART-2) is used to examine the evolution of pollutant O3 in the upper troposphere over the Indian region. Vertical profiles of ozone mixing ratio retrieved from Microwave Limb Sounder (MLS) aboard Earth Observing System (EOS) AURA satellite for the period 2005–2009 and Tropospheric Emission Spectrometer (TES) aboard (EOS) AURA for the period 2006–2007 has been analyzed. The satellite observations reveal the evidence of downward propagation of ozone (100–200 ppb) due to stratospheric intrusion during the winter and pre-monsoon seasons. The regular feature of enhancement of ozone in the upper troposphere over India is presented. Results obtained by the MOZART-2 simulations (for years 2000–2005) confirm the observations and indicate stratospheric intrusion of O3 during winter and pre-monsoon seasons. Observed enhanced O3 mixing ratio in the upper troposphere is explained by, variation of Potential Vorticity (PV), tropopause pressure, relative humidity and CO-O3 correlation.

scholarly journals Deriving an atmospheric budget of total organic bromine using airborne in situ measurements from the western Pacific area during SHIVA

2014 ◽  
Vol 14 (13) ◽  
pp. 6903-6923 ◽  
Author(s):  
S. Sala ◽  
H. Bönisch ◽  
T. Keber ◽  
D. E. Oram ◽  
G. Mills ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Radiative Heating ◽  
Western Pacific ◽  
Data Set ◽  
Tropical Regions ◽  
Upper Troposphere ◽  
Tropical Tropopause ◽  
Vertical Range ◽  
The Western Pacific

Abstract. During the recent SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project an extensive data set of all halogen species relevant for the atmospheric budget of total organic bromine was collected in the western Pacific region using the Falcon aircraft operated by the German Aerospace agency DLR (Deutsches Zentrum für Luft- und Raumfahrt) covering a vertical range from the planetary boundary layer up to the ceiling altitude of the aircraft of 13 km. In total, more than 700 measurements were performed with the newly developed fully automated in situ instrument GHOST-MS (Gas chromatograph for the Observation of Tracers – coupled with a Mass Spectrometer) by the Goethe University of Frankfurt (GUF) and with the onboard whole-air sampler WASP with subsequent ground-based state-of-the-art GC / MS analysis by the University of East Anglia (UEA). Both instruments yield good agreement for all major (CHBr3 and CH2Br2) and minor (CH2BrCl, CHBrCl2 and CHBr2Cl) VSLS (very short-lived substances), at least at the level of their 2σ measurement uncertainties. In contrast to the suggestion that the western Pacific could be a region of strongly increased atmospheric VSLS abundance (Pyle et al., 2011), we found only in the upper troposphere a slightly enhanced amount of total organic bromine from VSLS relative to the levels reported in Montzka and Reimann et al. (2011) for other tropical regions. From the SHIVA observations in the upper troposphere, a budget for total organic bromine, including four halons (H-1301, H-1211, H-1202, H-2402), CH3Br and the VSLS, is derived for the level of zero radiative heating (LZRH), the input region for the tropical tropopause layer (TTL) and thus also for the stratosphere. With the exception of the two minor VSLS CHBrCl2 and CHBr2Cl, excellent agreement with the values reported in Montzka and Reimann et al. (2011) is found, while being slightly higher than previous studies from our group based on balloon-borne measurements.

scholarly journals Global carbon monoxide products from combined AIRS, TES and MLS measurements on A-train satellites

2013 ◽  
Vol 13 (6) ◽  
pp. 15409-15441
Author(s):  
J. X. Warner ◽  
R. Yang ◽  
Z. Wei ◽  
F. Carminati ◽  
A. Tangborn ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Data Fusion ◽  
Lower Troposphere ◽  
Atmospheric Infrared Sounder ◽  
Upper Troposphere ◽  
In Situ Data ◽  
Diode Laser Spectrometer ◽  
Spatial Coverage ◽  
Transport Experiment

Abstract. This study tests a novel methodology to add value to satellite datasets. This methodology, data fusion, is similar to data assimilation, except that the background model-based field is replaced by a satellite dataset, in this case AIRS (Atmospheric Infrared Sounder) carbon monoxide (CO) measurements. The observational information comes from CO measurements with lower spatial coverage than AIRS, namely, from TES (Tropospheric Emission Spectrometer) and MLS (Microwave Limb Sounder). We show that combining these datasets with data fusion uses the higher spectral resolution of TES to extend AIRS CO observational sensitivity to the lower troposphere, a region especially important for air quality studies. We also show that combined CO measurements from AIRS and MLS provide enhanced information in the UTLS (upper troposphere/lower stratosphere) region compared to each product individually. The combined AIRS/TES and AIRS/MLS CO products are validated against DACOM (differential absorption mid-IR diode laser spectrometer) in situ CO measurements from the INTEX-B (Intercontinental Chemical Transport Experiment: MILAGRO and Pacific phases) field campaign and in situ data from HIPPO (HIAPER Pole-to-Pole Observations) flights. The data fusion results show improved sensitivities in the lower and upper troposphere (20–30% and above 20%, respectively) as compared with AIRS-only retrievals, and improved coverage compared with TES and MLS CO data.

scholarly journals Evaluation of balloon and satellite water vapour measurements in the Southern tropical UTLS during the HIBISCUS campaign

2007 ◽  
Vol 7 (3) ◽  
pp. 6037-6075 ◽  
Author(s):  
N. Montoux ◽  
A. Hauchecorne ◽  
J.-P. Pommereau ◽  
G. Durry ◽  
B. Morel ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
Transport Model ◽  
Tunable Diode Laser ◽  
Upper Troposphere ◽  
Satellite Systems ◽  
Mixing Ratios ◽  
Tropical Tropopause ◽  
Dry Bias

Abstract. Among the objectives of the HIBISCUS campaign was the study of water vapour in the tropical upper troposphere and lower stratosphere (UTLS) by balloon borne in situ and remote sensing, offering a unique opportunity for evaluating the performances of balloon and satellite water vapour data available at the southern tropics in February-April 2004. Instruments evaluated include balloon borne in situ tunable diode laser spectrometer (μ SDLA) and surface acoustic wave hygrometer (SAW), and remote sensing with a near IR spectrometer (SAOZ) flown on a circumnavigating long duration balloon. The satellite systems available are those of AIRS/AMSU (v4), SAGE-II (v6.2), HALOE (v19), MIPAS (v4.62) and GOMOS (v6.0). In the stratosphere between 20–25 km, three satellite instruments, HALOE, SAGE-II and MIPAS, are showing very consistent results (nearly constant mixing ratios), while AIRS, GOMOS and the SAOZ balloon are displaying a slight increase with altitude. Considering the previous studies, the first three appear the most precise at this level, HALOE being the less variable (5%), close to the atmospheric variability shown by the REPROBUS/ECMWF Chemistry-Transport model. The three others are showing significantly larger variability, AIRS being the most variable (35%), followed by GOMOS (25%) and SAOZ (20%). Lower down in the Tropical Tropopause Layer between 14–20 km, HALOE and SAGE-II are showing marked minimum mixing ratios around 17–19 km, not seen by all others. For HALOE, this might be related to an altitude registration error already identified on ozone, while for SAGE-II, a possible explanation could be the persistence of the dry bias displayed by previous retrieval versions, not completely removed in version 6.2. On average, MIPAS is consistent with AIRS, GOMOS and SAOZ, not displaying the dry bias observed in past versions, but a fast degradation of precision below 20 km. Compared to satellites, the μ SDLA measurements shows systematically larger humidity although this conclusion may be biased by the fact that the balloon flights were carried out intentionally next or above strong convective systems where remote observations from space are difficult. In the upper troposphere below 14 km, all remote sensing measurements (except MIPAS of limited precision, and AIRS/AMSU) become rare, dry biased and less variable compared to ECMWF, but particularly HALOE and SAGE-II. The main reason for that is the frequent masking by clouds within which no remote measurements could be performed except by the AMSU microwave. Water vapour remote sensing profiles are representative of cloud free conditions only and thus dryer and less variable on average than ECMWF and AIRS/AMSU. Always in the upper troposphere, two in-situ instruments, μ SDLA and SAW, flown on the same balloon agree each other, displaying water vapour mixing ratios 100–200% larger than that of HALOE and MIPAS, which could be explained by the large ice supersaturation of the layer up to the tropopause, hardly detectable from the orbit.

scholarly journals Methane plume over South Asia during the monsoon season: satellite observation and model simulation

2008 ◽  
Vol 8 (4) ◽  
pp. 13453-13478 ◽  
Author(s):  
X. Xiong ◽  
S. Houweling ◽  
J. Wei ◽  
E. Maddy ◽  
F. Sun ◽  
...  
Keyword(s):  
South Asia ◽  
Transport Process ◽  
Model Simulation ◽  
Monsoon Season ◽  
Satellite Observation ◽  
Satellite Observations ◽  
Atmospheric Pollutants ◽  
Local Surface ◽  
Atmospheric Infrared Sounder ◽  
Upper Troposphere

Abstract. Satellite observations of methane (CH4) using the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua platform from 2003–2007 demonstrate a strong, plume-like enhancement of CH4 in the middle to upper troposphere over the South Asia during July, August and September, and its maximum occurs in early September. Simulations using the global tracer model version 3 (TM3) also show similar seasonal enhancement of CH4 in the same region. The model results also suggest that this enhancement is associated with transport process and local surface emissions, thus the observations to tropospheric CH4during the monsoon season may be used to constrain the models for a better estimation of Asian CH4 sources. Further comparisons between AIRS observations and the model simulations indicate a possible overestimate of CH4 emissions from rice paddies in Southeast Asia. Moreover, the observed tropospheric CH4 enhancement from AIRS provides evidence for the strong transport of atmospheric pollutants from the lower to the upper troposphere in Asia during the monsoon season, and the observed rapid disappearance of local CH4 maximum in September may provide valuable information for studying the dissipation of the Tibetan anticyclone and the withdrawal of monsoon.

scholarly journals Tropical thin cirrus and relative humidity observed by the Atmospheric Infrared Sounder

2008 ◽  
Vol 8 (6) ◽  
pp. 1501-1518 ◽  
Author(s):  
B. H. Kahn ◽  
C. K. Liang ◽  
A. Eldering ◽  
A. Gettelman ◽  
Q. Yue ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Climate Models ◽  
Temporal Variations ◽  
Ocean Basin ◽  
Specific Humidity ◽  
Future Climate Change ◽  
Effective Diameter ◽  
Regional Variability ◽  
Atmospheric Infrared Sounder

Abstract. Global observations of cloud and humidity distributions in the upper troposphere within all geophysical conditions are critically important in order to monitor the present climate and to provide necessary data for validation of climate models to project future climate change. Towards this end, tropical oceanic distributions of thin cirrus optical depth (τ), effective diameter (De), and relative humidity with respect to ice (RHi) within cirrus (RHic) are simultaneously derived from the Atmospheric Infrared Sounder (AIRS). Corresponding increases in De and cloud temperature are shown for cirrus with τ>0.25 that demonstrate quantitative consistency to other surface-based, in situ and satellite retrievals. However, inferred cirrus properties are shown to be less certain for increasingly tenuous cirrus. In-cloud supersaturation is observed for 8–12% of thin cirrus and is several factors higher than all-sky conditions; even higher frequencies are shown for the coldest and thinnest cirrus. Spatial and temporal variations in RHic correspond to cloud frequency while regional variability in RHic is observed to be most prominent over the N. Indian Ocean basin. The largest cloud/clear sky RHi anomalies tend to occur in dry regions associated with vertical descent in the sub-tropics, while the smallest occur in moist ascending regions in the tropics. The characteristics of RHic frequency distributions depend on τ and a peak frequency is located between 60–80% that illustrates RHic is on average biased dry. The geometrical thickness of cirrus is typically less than the vertical resolution of AIRS temperature and specific humidity profiles and thus leads to the observed dry bias, shown with coincident cloud vertical structure obtained from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The joint distributions of thin cirrus microphysics and humidity derived from AIRS provide unique and important regional and global-scale insights on upper tropospheric processes not available from surface, in situ, and other contemporary satellite observing platforms.

scholarly journals A 6-year global climatology of occurrence of upper-tropospheric ice supersaturation inferred from the Atmospheric Infrared Sounder after synergetic calibration with MOZAIC

2011 ◽  
Vol 11 (4) ◽  
pp. 12889-12947
Author(s):  
N. Lamquin ◽  
C. J. Stubenrauch ◽  
K. Gierens ◽  
U. Burkhardt ◽  
H. Smit
Keyword(s):  
Relative Humidity ◽  
Calibration Method ◽  
Cloud Formation ◽  
Orthogonal Polarization ◽  
Occurrence Probability ◽  
Atmospheric Infrared Sounder ◽  
Upper Troposphere ◽  
European Centre ◽  
Cloud Properties ◽  
Humidity Measurements

Abstract. Ice supersaturation in the upper troposphere is a complex and important issue for the understanding of cirrus cloud formation. Infrared sounders have the ability to provide cloud properties and atmospheric profiles of temperature and humidity. On the other hand, they suffer from coarse vertical resolution, especially in the upper troposphere and therefore are unable to detect shallow ice supersaturated layers. We have used data from the Measurements of OZone and water vapour by AIrbus in-service airCraft experiment (MOZAIC) in combination with Atmospheric InfraRed Sounder (AIRS) relative humidity measurements and cloud properties to develop a calibration method for an estimation of occurrence frequencies of ice supersaturation. This method first determines the occurrence probability of ice supersaturation, detected by MOZAIC, as a function of the relative humidity determined by AIRS. The occurrence probability function is then applied to AIRS data, independently of the MOZAIC data, to provide a global climatology of upper-tropospheric ice supersaturation occurrence. Our climatology is then related to high cloud occurrence from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and compared to ice supersaturation occurrence statistics from MOZAIC alone. Finally it is compared to model climatologies of ice supersaturation from the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) and from the European Centre HAmburg Model (ECHAM). All the comparisons show good agreements when considering the limitations of each instrument and model. This study highlights the benefits of multi-instrumental synergies for the investigation of upper tropospheric ice supersaturation.

scholarly journals A global climatology of upper-tropospheric ice supersaturation occurrence inferred from the Atmospheric Infrared Sounder calibrated by MOZAIC

2012 ◽  
Vol 12 (1) ◽  
pp. 381-405 ◽  
Author(s):  
N. Lamquin ◽  
C. J. Stubenrauch ◽  
K. Gierens ◽  
U. Burkhardt ◽  
H. Smit
Keyword(s):  
Relative Humidity ◽  
Calibration Method ◽  
Cloud Formation ◽  
Orthogonal Polarization ◽  
Occurrence Probability ◽  
Atmospheric Infrared Sounder ◽  
Upper Troposphere ◽  
European Centre ◽  
Cloud Properties ◽  
Humidity Measurements

Abstract. Ice supersaturation in the upper troposphere is a complex and important issue for the understanding of cirrus cloud formation. On one hand, infrared sounders have the ability to provide cloud properties and atmospheric profiles of temperature and humidity. On the other hand, they suffer from coarse vertical resolution, especially in the upper troposphere and therefore are unable to detect shallow ice supersaturated layers. We have used data from the Measurements of OZone and water vapour by AIrbus in-service airCraft experiment (MOZAIC) in combination with Atmospheric InfraRed Sounder (AIRS) relative humidity measurements and cloud properties to develop a calibration method for an estimation of occurrence frequencies of ice supersaturation. This method first determines the occurrence probability of ice supersaturation, detected by MOZAIC, as a function of the relative humidity determined by AIRS. The occurrence probability function is then applied to AIRS data, independently of the MOZAIC data, to provide a global climatology of upper-tropospheric ice supersaturation occurrence. Our climatology is then compared to ice supersaturation occurrence statistics from MOZAIC alone and related to high cloud occurrence from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). As an example of application it is compared to model climatologies of ice supersaturation from the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) and from the European Centre HAmburg Model (ECHAM4). This study highlights the benefits of multi-instrumental synergies for the investigation of upper tropospheric ice supersaturation.

scholarly journals Vertical transport rates and concentrations of OH and Cl radicals in the Tropical Tropopause Layer from Observations of CO<sub>2</sub> and halocarbons: implications for distributions of long- and short-lived chemical species

2010 ◽  
Vol 10 (3) ◽  
pp. 6059-6095
Author(s):  
S. Park ◽  
E. L. Atlas ◽  
R. Jiménez ◽  
B. C. Daube ◽  
E. W. Gottlieb ◽  
...  
Keyword(s):  
Large Scale ◽  
Chemical Species ◽  
Vertical Transport ◽  
Upward Movement ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Validation Experiment ◽  
In Situ Observations

Abstract. Rates for large-scale vertical transport of air in the Tropical Tropopause Layer (TTL) were determined using high-resolution, in situ observations of CO2 concentrations in the tropical upper troposphere and lower stratosphere during the NASA Tropical Composition, Cloud and Climate Coupling (TC4) campaign in August 2007. Upward movement of trace gases in the deep tropics was notably slower in TC4 than during the Costa Rica AURA Validation Experiment (CR-AVE), in January 2006. Transport rates in the TTL were combined with in situ measurements of chlorinated and brominated organic compounds from whole air samples to determine chemical loss rates for reactive chemical species, providing empirical vertical profiles for 24-h mean concentrations of hydroxyl radicals (OH) and chlorine atoms in the TTL. The analysis shows that important short-lived species such as CHCl3, CH2Cl2, and CH2Br2 have longer chemical lifetimes than the time for transit of the TTL, implying that these species, which are not included in most models, could readily reach the stratosphere and make significant contributions of chlorine and/or bromine to stratospheric loading.

scholarly journals Tropical thin cirrus and relative humidity observed by the Atmospheric Infrared Sounder

2007 ◽  
Vol 7 (6) ◽  
pp. 16185-16225 ◽  
Author(s):  
B. H. Kahn ◽  
C. K. Liang ◽  
A. Eldering ◽  
A. Gettelman ◽  
Q. Yue ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Climate Models ◽  
Temporal Variations ◽  
Ocean Basin ◽  
Specific Humidity ◽  
Future Climate Change ◽  
Effective Diameter ◽  
Regional Variability ◽  
Atmospheric Infrared Sounder

Abstract. Global observations of cloud and humidity distributions in the upper troposphere within all geophysical conditions are critically important in order to monitor the present climate and to provide necessary data for validation of climate models to project future climate change. Towards this end, tropical oceanic distributions of thin cirrus optical depth (τ), effective diameter (De), and relative humidity with respect to ice (RHi) within cirrus (RHic) are simultaneously derived from the Atmospheric Infrared Sounder (AIRS). Corresponding increases in De and cloud temperature are shown for cirrus with τ>0.25 that demonstrate quantitative consistency to other surface-based, in situ and satellite retrievals of cirrus. However, inferred cirrus properties are shown to be less certain for increasingly tenuous cirrus. In-cloud supersaturation is observed for 8–12% of thin cirrus and is several factors higher than all-sky conditions; even higher frequencies are shown for the coldest and thinnest cirrus. Spatial and temporal variations in RHic correspond to cloud frequency while regional variability in RHic is observed to be most prominent over the N. Indian Ocean basin. The largest cloud/clear sky RHi anomalies tend to occur in dry regions associated with vertical descent in the sub-tropics, while the smallest occur in moist ascending regions in the tropics. The characteristics of RHic frequency distributions depend on τ and a peak frequency is located between 60–80% that illustrates RHic is on average biased dry. The geometrical thickness of cirrus is typically less than the vertical resolution of AIRS temperature and specific humidity profiles and thus leads to the observed dry bias, shown with coincident cloud vertical structure obtained from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The joint distributions of thin cirrus microphysics and humidity derived from AIRS provide unique and important regional and global-scale insights on upper tropospheric processes not available from surface, in situ, and other contemporary satellite observing platforms.

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