scholarly journals Variability of Stratospheric Water Vapor Inferred from SAGE II, HALOE, and Boulder (Colorado) Balloon Measurements

2006 ◽  
Vol 19 (16) ◽  
pp. 4121-4133 ◽  
Author(s):  
E. W. Chiou ◽  
L. W. Thomason ◽  
W. P. Chu
Keyword(s):  
Water Vapor ◽  
Correlation Coefficients ◽  
Quantitative Agreement ◽  
Stratospheric Aerosol ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
Frost Point ◽  
The North ◽  
Low Latitudes ◽  
Balloon Measurements

Abstract The variability of stratospheric water vapor between 1996 and 2004 has been studied using multiyear measurements from the Stratospheric Aerosol and Gas Experiment II (SAGE II) version 6.2 dataset, the Halogen Occultation Experiment (HALOE) version 19 dataset, and the balloon-borne frost point hygrometer data record at Boulder, Colorado (40°N, 105°W). The features derived from SAGE II and HALOE for 20° latitudinal zones from 60°S to 60°N at various altitudes (16–34 km) show good quantitative agreement regarding the phases and magnitudes of annual, semiannual, and quasi-biennial oscillations (QBO). For the latitudinal zones 20°–40° and 40°–60°, the hemispheric asymmetry at 22 km with mainly QBO in the north and predominantly annual oscillations in the south has been revealed by both SAGE II and HALOE observations. Strong correlation exists between SAGE II and HALOE lower-stratospheric H2O anomalies over low latitudes and 100-hPa tropical zonal mean temperature anomalies. The correlation coefficients based on the 0°–20°S water vapor time series with H2O lagged by 2 months are 0.81 and 0.70 for HALOE and SAGE II, respectively. For 35°–45°N, SAGE II and HALOE show consistent trends generally varying from −0.05 to −0.02 ppmv yr−1 between 16 and 34 km. The corresponding analyses based on frost point measurements over Boulder show insignificant trends. These trends are not strongly dependent on the end points of the analysis and stand in contrast to the positive trends reported in previous studies that include data records prior to 1994. For the lower stratosphere, investigations of the entire balloon-borne dataset over Boulder indicate higher values of mixing ratios after 1992–93 compared to the period 1980–92. In contrast, SAGE II monthly zonal mean measurements for 35°–45°N show insignificant differences between the periods 1987–89 and 1996–2004.

scholarly journals Enhanced stratospheric water vapor over the summertime continental United States and the role of overshooting convection

2017 ◽  
Vol 17 (9) ◽  
pp. 6113-6124 ◽  
Author(s):  
Robert L. Herman ◽  
Eric A. Ray ◽  
Karen H. Rosenlof ◽  
Kristopher M. Bedka ◽  
Michael J. Schwartz ◽  
...  
Keyword(s):  
United States ◽  
Water Vapor ◽  
Trajectory Analysis ◽  
The United States ◽  
Atmospheric Composition ◽  
Back Trajectory ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
The North ◽  
Back Trajectory Analysis

Abstract. The NASA ER-2 aircraft sampled the lower stratosphere over North America during the field mission for the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS). This study reports observations of convectively influenced air parcels with enhanced water vapor in the overworld stratosphere over the summertime continental United States and investigates three case studies in detail. Water vapor mixing ratios greater than 10 ppmv, which is much higher than the background 4 to 6 ppmv of the overworld stratosphere, were measured by the JPL Laser Hygrometer (JLH Mark2) at altitudes between 16.0 and 17.5 km (potential temperatures of approximately 380 to 410 K). Overshooting cloud tops (OTs) are identified from a SEAC4RS OT detection product based on satellite infrared window channel brightness temperature gradients. Through trajectory analysis, we make the connection between these in situ water measurements and OT. Back trajectory analysis ties enhanced water to OT 1 to 7 days prior to the intercept by the aircraft. The trajectory paths are dominated by the North American monsoon (NAM) anticyclonic circulation. This connection suggests that ice is convectively transported to the overworld stratosphere in OT events and subsequently sublimated; such events may irreversibly enhance stratospheric water vapor in the summer over Mexico and the United States. A regional context is provided by water observations from the Aura Microwave Limb Sounder (MLS).

scholarly journals Enhanced Stratospheric Water Vapor over the Summertime Continental United States and the Role of Overshooting Convection

2016 ◽  
Author(s):  
Robert L. Herman ◽  
Eric A. Ray ◽  
Karen H. Rosenlof ◽  
Kristopher M. Bedka ◽  
Michael J. Schwartz ◽  
...  
Keyword(s):  
United States ◽  
Water Vapor ◽  
The United States ◽  
Atmospheric Composition ◽  
North American Monsoon ◽  
Back Trajectory ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
The North ◽  
Back Trajectory Analysis

Abstract. The NASA ER-2 aircraft sampled the UTLS region over North America during the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field mission. This study reports three case studies of convectively-influenced air parcels with enhanced water vapor in the overworld stratosphere over the summertime continental United States. Water vapor mixing ratios greater than 10 ppmv, more than twice the stratospheric background levels, were measured by the JPL Laser Hygrometer (JLH Mark2) at pressure levels between 80 and 160 hPa. Through satellite observations and analysis, we make the connection between these in situ water measurements and overshooting cloud tops. The overshooting tops (OT) are identified from a SEAC4RS OT detection product based on satellite infrared window channel brightness temperature gradients. Back trajectory analysis ties enhanced water to OT one to seven days prior to the intercept by the aircraft. The trajectory paths are dominated by the North American Monsoon (NAM) anticyclonic circulation. This connection suggests that ice is convectively transported to the overworld stratosphere in OT events and subsequently sublimated; such events may irreversibly enhance stratospheric water vapor in the summer over Mexico and the United States. Regional context is provided by water observations from the Aura Microwave Limb Sounder (MLS).

scholarly journals Impacts of Ozone Changes in the Tropopause Layer on Stratospheric Water Vapor

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 291
Author(s):  
Jinpeng Lu ◽  
Fei Xie ◽  
Hongying Tian ◽  
Jiali Luo
Keyword(s):  
Water Vapor ◽  
Ozone Depletion ◽  
Climate Model ◽  
Global Climate ◽  
Stratospheric Water Vapor ◽  
Radiative Processes ◽  
Low Latitudes ◽  
Cold Point ◽  
The Impact ◽  
Tropopause Temperature

Stratospheric water vapor (SWV) changes play an important role in regulating global climate change, and its variations are controlled by tropopause temperature. This study estimates the impacts of tropopause layer ozone changes on tropopause temperature by radiative process and further influences on lower stratospheric water vapor (LSWV) using the Whole Atmosphere Community Climate Model (WACCM4). It is found that a 10% depletion in global (mid-low and polar latitudes) tropopause layer ozone causes a significant cooling of the tropical cold-point tropopause with a maximum cooling of 0.3 K, and a corresponding reduction in LSWV with a maximum value of 0.06 ppmv. The depletion of tropopause layer ozone at mid-low latitudes results in cooling of the tropical cold-point tropopause by radiative processes and a corresponding LSWV reduction. However, the effect of polar tropopause layer ozone depletion on tropical cold-point tropopause temperature and LSWV is opposite to and weaker than the effect of tropopause layer ozone depletion at mid-low latitudes. Finally, the joint effect of tropopause layer ozone depletion (at mid-low and polar latitudes) causes a negative cold-point tropopause temperature and a decreased tropical LSWV. Conversely, the impact of a 10% increase in global tropopause layer ozone on LSWV is exactly the opposite of the impact of ozone depletion. After 2000, tropopause layer ozone decreased at mid-low latitudes and increased at high latitudes. These tropopause layer ozone changes at different latitudes cause joint cooling in the tropical cold-point tropopause and a reduction in LSWV. Clarifying the impacts of tropopause layer ozone changes on LSWV clearly is important for understanding and predicting SWV changes in the context of future global ozone recovery.

scholarly journals Intercomparison of midlatitude tropospheric and lower-stratospheric water vapor measurements and comparison to ECMWF humidity data

2018 ◽  
Vol 18 (22) ◽  
pp. 16729-16745 ◽  
Author(s):  
Stefan Kaufmann ◽  
Christiane Voigt ◽  
Romy Heller ◽  
Tina Jurkat-Witschas ◽  
Martina Krämer ◽  
...  
Keyword(s):  
Water Vapor ◽  
Climate Impact ◽  
Cloud Formation ◽  
Mean Values ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
Quality Of Water ◽  
Research Aircraft ◽  
German Aerospace

Abstract. Accurate measurement of water vapor in the climate-sensitive region near the tropopause is very challenging. Unexplained systematic discrepancies between measurements at low water vapor mixing ratios made by different instruments on airborne platforms have limited our ability to adequately address a number of relevant scientific questions on the humidity distribution, cloud formation and climate impact in that region. Therefore, during the past decade, the scientific community has undertaken substantial efforts to understand these discrepancies and improve the quality of water vapor measurements. This study presents a comprehensive intercomparison of airborne state-of-the-art in situ hygrometers deployed on board the DLR (German Aerospace Center) research aircraft HALO (High Altitude and LOng Range Research Aircraft) during the Midlatitude CIRRUS (ML-CIRRUS) campaign conducted in 2014 over central Europe. The instrument intercomparison shows that the hygrometer measurements agree within their combined accuracy (±10 % to 15 %, depending on the humidity regime); total mean values agree within 2.5 %. However, systematic differences on the order of 10 % and up to a maximum of 15 % are found for mixing ratios below 10 parts per million (ppm) H2O. A comparison of relative humidity within cirrus clouds does not indicate a systematic instrument bias in either water vapor or temperature measurements in the upper troposphere. Furthermore, in situ measurements are compared to model data from the European Centre for Medium-Range Weather Forecasts (ECMWF) which are interpolated along the ML-CIRRUS flight tracks. We find a mean agreement within ±10 % throughout the troposphere and a significant wet bias in the model on the order of 100 % to 150 % in the stratosphere close to the tropopause. Consistent with previous studies, this analysis indicates that the model deficit is mainly caused by too weak of a humidity gradient at the tropopause.

Water-vapor Measurements in the Lower Stratosphere

1974 ◽  
Vol 52 (8) ◽  
pp. 1527-1531 ◽  
Author(s):  
H. J. Mastenbrook
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Marked Decrease ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Mixing Ratio ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
Natural Concentration ◽  
General Range

Nearly 10 years of water-vapor measurements to heights of 30 km provide a basis for assessing the natural concentration of stratospheric water vapor and its variability. The measurements which began in 1964 have been made at monthly intervals from the mid-latitude location of Washington, D.C, using a balloon-borne frost-point hygrometer. The observations show the mixing ratio of water-vapor mass to air mass in the stratosphere to be in the general range of 1 to 4 p.p.m. with a modal concentration between 2 and 3 p.p.m. An annual cycle of mixing ratio is evident for the low stratosphere. A trend of water-vapor increase observed during the first 6 years does not persist beyond 1969 or 1970. The 6 year increase was followed by a marked decrease in 1971, with mixing ratios remaining generally below 3 p.p.m. thereafter. The measurements of recent years suggest that the series of observations may have begun during a period of low water-vapor concentration in the stratosphere.

scholarly journals Dehydration of the stratosphere

2011 ◽  
Vol 11 (16) ◽  
pp. 8433-8446 ◽  
Author(s):  
M. R. Schoeberl ◽  
A. E. Dessler
Keyword(s):  
Water Vapor ◽  
Gravity Waves ◽  
Small Contribution ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
Trajectory Calculations ◽  
Tropical Tropopause ◽  
Type Water ◽  
Dehydration Processes ◽  
Tropopause Temperature

Abstract. 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.

scholarly journals Recent divergences in stratospheric water vapor measurements by frost point hygrometers and the Aura Microwave Limb Sounder

2016 ◽  
Author(s):  
Dale F. Hurst ◽  
William G. Read ◽  
Holger Vömel ◽  
Henry B. Selkirk ◽  
Karen H. Rosenlof ◽  
...  
Keyword(s):  
Water Vapor ◽  
Linear Regression Analysis ◽  
San Jose ◽  
Average Growth ◽  
Upper Troposphere ◽  
Stratospheric Water Vapor ◽  
Frost Point ◽  
Comparison Period ◽  
Better Than

Abstract. Balloon-borne frost point hygrometers (FPs) and the Aura Microwave Limb Sounder (MLS) provide high-quality vertical profile measurements of water vapor in the upper troposphere and lower stratosphere (UTLS). A previous comparison of stratospheric water vapor measurements by FPs and MLS over three FP sites, Boulder, Colorado (40.0° N), Hilo, Hawaii (19.7° N) and Lauder, New Zealand (45.0° S), from August 2004 through December 2012, demonstrated agreement better than 1 % between 68 and 26 hPa, but also exposed statistically significant biases of 2 to 10 % at 83 and 100 hPa (Hurst et al., 2014). A simple linear regression analysis of the FPH-MLS differences revealed no significant long-term drifts between the two instruments. Here we extend the drift comparison to mid-2015 and add two FP sites, Lindenberg, Germany (52.2° N) and San José, Costa Rica (10.0° N) that employ FPs of different manufacture and calibration for their water vapor soundings. The extended comparison period reveals that stratospheric FP and MLS measurements over 4 of the 5 sites have diverged at rates of 0.03 to 0.07 ppmv yr−1 (0.6 to 1.5 % yr−1) from ~2010 to mid-2015. These rates are similar in magnitude to the 30-year (1980–2010) average growth rate of stratospheric water vapor (~1 % yr−1) measured by FPs over Boulder (Hurst et al., 2011). By mid-2015, the FP-MLS differences at some sites were large enough to exceed the combined accuracy estimates of the FP and MLS measurements.

scholarly journals Evaluating the capability of regional-scale air quality models to capture the vertical distribution of pollutants

2013 ◽  
Vol 6 (3) ◽  
pp. 791-818 ◽  
Author(s):  
E. Solazzo ◽  
R. Bianconi ◽  
G. Pirovano ◽  
M. D. Moran ◽  
R. Vautard ◽  
...  
Keyword(s):  
Air Quality ◽  
Correlation Coefficient ◽  
Regional Scale ◽  
Model Performance ◽  
Correlation Coefficients ◽  
Surface Processes ◽  
Free Troposphere ◽  
Commercial Aircraft ◽  
Mixing Ratios ◽  
The North

Abstract. This study is conducted in the framework of the Air Quality Modelling Evaluation International Initiative (AQMEII) and aims at the operational evaluation of an ensemble of 12 regional-scale chemical transport models used to predict air quality over the North American (NA) and European (EU) continents for 2006. The modelled concentrations of ozone and CO, along with the meteorological fields of wind speed (WS) and direction (WD), temperature (T), and relative humidity (RH), are compared against high-quality in-flight measurements collected by instrumented commercial aircraft as part of the Measurements of OZone, water vapour, carbon monoxide and nitrogen oxides by Airbus In-service airCraft (MOZAIC) programme. The evaluation is carried out for five model domains positioned around four major airports in NA (Portland, Philadelphia, Atlanta, and Dallas) and one in Europe (Frankfurt), from the surface to 8.5 km. We compare mean vertical profiles of modelled and measured variables for all airports to compute error and variability statistics, perform analysis of altitudinal error correlation, and examine the seasonal error distribution for ozone, including an estimation of the bias introduced by the lateral boundary conditions (BCs). The results indicate that model performance is highly dependent on the variable, location, season, and height (e.g. surface, planetary boundary layer (PBL) or free troposphere) being analysed. While model performance for T is satisfactory at all sites (correlation coefficient in excess of 0.90 and fractional bias ≤ 0.01 K), WS is not replicated as well within the PBL (exhibiting a positive bias in the first 100 m and also underestimating observed variability), while above 1000 m, the model performance improves (correlation coefficient often above 0.9). The WD at NA airports is found to be biased in the PBL, primarily due to an overestimation of westerly winds. RH is modelled well within the PBL, but in the free troposphere large discrepancies among models are observed, especially in EU. CO mixing ratios show the largest range of modelled-to-observed standard deviations of all the examined species at all heights and for all airports. Correlation coefficients for CO are typically below 0.6 for all sites and heights, and large errors are present at all heights, particularly in the first 250 m. Model performance for ozone in the PBL is generally good, with both bias and error within 20%. Profiles of ozone mixing ratios depend strongly on surface processes, revealed by the sharp gradient in the first 2 km (10 to 20 ppb km−1). Modelled ozone in winter is biased low at all locations in the NA, primarily due to an underestimation of ozone from the BCs. Most of the model error in the PBL is due to surface processes (emissions, transport, photochemistry), while errors originating aloft appear to have relatively limited impact on model performance at the surface. Suggestions for future work include interpretation of the model-to-model variability and common sources of model bias, and linking CO and ozone bias to the bias in the meteorological fields. Based on the results from this study, we suggest possible in-depth, process-oriented and diagnostic investigations to be carried out next.

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