Revisiting the factors that drive interannual variability in stratospheric entry water vapour

2020 ◽  
Author(s):  
Shlomi Ziskin Ziv ◽  
Chaim I. Garfinkel
Keyword(s):  
Water Vapor ◽  
Interannual Variability ◽  
Large Scale ◽  
Trace Gases ◽  
Transport Processes ◽  
Tropospheric Temperature ◽  
Stratospheric Water Vapor ◽  
Cold Point ◽  
Stratospheric Trace Gases

<p>Understanding the sinks, sources and transport processes of stratospheric trace gases can improve our prediction of mid to long term climate change. In this study we consider the processes that lead to variability in stratospheric water vapor. We perform a Multiple Linear Regression(MLR) on the SWOOSH combined anomaly filled water vapor product with ENSO, QBO, BDC, mid-tropospheric temperature, and CH4 as predictors, in an attempt to find the factors that most succinctly explain observed water vapor variability. We also consider the fraction of entry water vapor variability that can be accounted for by variations of the cold point temperature as an upper bound on how much water vapor variability is predictable from large scale processes. Several periods in which the MLR fails to account for interannual variability are treated as case studies in order to better understand variability in entry water not governed by these large scale processes.</p>

scholarly journals A Study of the Free Tropospheric Humidity Interannual Variability Using Meteosat Data and an Advection–Condensation Transport Model

2009 ◽  
Vol 22 (24) ◽  
pp. 6773-6787 ◽  
Author(s):  
Hélène Brogniez ◽  
Rémy Roca ◽  
Laurence Picon
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Interannual Variability ◽  
Large Scale ◽  
Transport Model ◽  
Radiation Budget ◽  
Lagrangian Model ◽  
Back Trajectory ◽  
Good Proxy

Abstract Water vapor in the midtroposphere is an important element for the earth radiation budget. Despite its importance, the relative humidity in the free troposphere is not very well documented, mainly because of the difficulties associated with its measurements. A new long-term archive of free tropospheric humidity (FTH) derived from the water vapor channel of the Meteosat satellite from 1983 to 2005 is introduced. Special attention is dedicated to the long-term homogeneity and the definition of the retrieval layer. It is shown to complement the existing databases and is used to establish the climatology of FTH. Interannual variability is then evaluated for each season by using a normalized interannual standard deviation. This normalization approach reveals the importance of the relative variability of the dry areas to the moist regions. In consequence, emphasis is on the driest area of the region. Focusing on composites of the moist and dry seasons of the time series, the authors demonstrate that the 500-hPa relative humidity field, reconstructed using an idealized Lagrangian model, is a good proxy for the FTH variability there. The analysis of the origin of the air mass, using the back trajectory model, points out that lateral mixing between the deep tropics and extratropical latitudes takes place over this area, as advocated in previous theoretical studies. Systematic estimation of this large-scale mixing shows that, indeed, a significant part of the interannual variability of the free tropospheric humidity in this subtropical region stems from the amount of mixing of air originating from the deep tropics versus extratropical latitudes. The importance of this mechanism in the general understanding of the FTH distribution and variability is then discussed.

scholarly journals Influence of ENSO on entry stratospheric water vapor in coupled chemistry-ocean CCMI and CMIP6 models

2020 ◽  
Author(s):  
Chaim Israel Garfinkel ◽  
Ohad Harari ◽  
Shlomi Ziskin ◽  
Jian Rao ◽  
Olaf Morgenstern ◽  
...  
Keyword(s):  
Water Vapor ◽  
Interannual Variability ◽  
El Niño ◽  
El Nino ◽  
Temperature Response ◽  
La Niña ◽  
Stratospheric Water Vapor ◽  
La Nina ◽  
Tropical Troposphere ◽  
Cold Point

Abstract. The connection between the dominant mode of interannual variability in the tropical troposphere, El Nino Southern Oscillation (ENSO), and entry of stratospheric water vapor, is analyzed in a set of the model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project and for phase 6 of the Coupled Model Intercomparison Project. While the models agree on the temperature response to ENSO in the tropical troposphere and lower stratosphere, and all models also agree on the zonal structure of the response in the tropical tropopause layer, the only aspect of the entry water vapor with consensus is that La Nina leads to moistening in winter relative to neutral ENSO. For El Nino and for other seasons there are significant differences among the models. For example, some models find that the enhanced water vapor for La Nina in the winter of the event reverses in spring and summer, other models find that this moistening persists, while some show a nonlinear response with both El Nino and La Nina leading to enhanced water vapor in both winter, spring, and summer. Focusing on Central Pacific ENSO versus East Pacific ENSO, or temperatures in the mid-troposphere as compared to temperatures near the surface, does not narrow the inter-model discrepancies. Despite this diversity in response, the temperature response near the cold point can explain the response of water vapor when each model is considered separately. While the observational record is too short to fully constrain the response to ENSO, it is clear that most models suffer from biases in the magnitude of interannual variability of entry water vapor. This bias could be due to missing forcing processes that contribute to observed variability in cold point temperatures.

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.

Oceanography of the New Zealand subantarctic region

2021 ◽  
Author(s):  
◽  
Aitana Forcén-Vázquez
Keyword(s):  
New Zealand ◽  
Interannual Variability ◽  
Water Column ◽  
Large Scale ◽  
Southern Oscillation ◽  
Complex Structure ◽  
Positive Trend ◽  
Intermediate Water ◽  
Subantarctic Region

<p>Subantarctic New Zealand is an oceanographycally dynamic region with the Subtropical Front (STF) to the north and the Subantarctic Front (SAF) to the south. This thesis investigates the ocean structure of the Campbell Plateau and the surrounding New Zealand subantarctic, including the spatial, seasonal, interannual and longer term variability over the ocean properties, and their connection to atmospheric variability using a combination of in-situ oceanographic measurements and remote sensing data.  The spatial and seasonal oceanographic structure in the New Zealand subantarctic region was investigated by analysing ten high resolution Conductivity Temperature and Depth (CTD) datasets, sampled during oceanographic cruises from May 1998 to February 2013. Position of fronts, water mass structure and changes over the seasons show a complex structure around the Campbell Plateau combining the influence of subtropical and subantarctic waters.  The spatial and interannual variability on the Campbell Plateau was described by analysing approximately 70 low resolution CTD profiles collected each year in December between 2002 and 2009. Conservative temperature and absolute salinity profiles reveal high variability in the upper 200m of the water column and a homogeneous water column from 200 to 600m depth. Temperature variability of about 0.7 °C, on occasions between consecutive years, is observed down to 900m depth. The presence of Subantarctic Mode Water (SAMW) on the Campbell Plateau is confirmed and Antarctic Intermediate Water (AAIW) reported for the first time in the deeper regions around the edges of the plateau.  Long-term trends and variability over the Campbell Plateau were investigated by analysing satellite derived Sea Level Anomalies (SLA) and Sea Surface Temperature (SST) time series. Links to large scale atmospheric processes are also explored through correlation with the Southern Oscillation Index (SOI) and Southern Annular Mode (SAM). SST shows a strong seasonality and interannual variability which is linked to local winds, but no significant trend is found. The SLA over the Campbell Plateau has increased at a rate of 5.2 cm decade⁻¹ in the last two decades. The strong positive trend in SLA appears to be a combination of the response of the ocean to wind stress curl (Ekman pumping), thermal expansion and ocean mass redistribution via advection amongst others.  These results suggest that the variability on the Campbell Plateau is influenced by the interaction of the STF and the SAF. The STF influence reaches the limit of the SAF over the western Campbell Plateau and the SAF influence extends all around the plateau. Results also suggest different connections between the plateau with the surrounding oceans, e.g., along the northern edge with the Bounty Trough and via the southwest edge with the SAF. A significant correlation with SOI and little correlation with SAM suggest a stronger response to tropically driven processes in the long-term variability on the Campbell Plateau.  The results of this thesis provide a new definitive assessment of the circulation, water masses and variability of the Campbell Plateau on mean, annual, and interannual time scales which will support research in other disciplines such as palaeoceanography, fisheries management and climate.</p>

scholarly journals Response of trace gases to the disrupted 2015–2016 quasi-biennial oscillation

2017 ◽  
Vol 17 (11) ◽  
pp. 6813-6823 ◽  
Author(s):  
Olga V. Tweedy ◽  
Natalya A. Kramarova ◽  
Susan E. Strahan ◽  
Paul A. Newman ◽  
Lawrence Coy ◽  
...  
Keyword(s):  
Water Vapor ◽  
Chemical Constituents ◽  
Trace Gases ◽  
Quasi Biennial Oscillation ◽  
Data Set ◽  
Uv Index ◽  
Stratospheric Water Vapor ◽  
Northern Summer ◽  
Tropical Tropopause ◽  
Biennial Oscillation

Abstract. The quasi-biennial oscillation (QBO) is a quasiperiodic alternation between easterly and westerly zonal winds in the tropical stratosphere, propagating downward from the middle stratosphere to the tropopause with a period that varies from 24 to 32 months ( ∼  28 months on average). The QBO wind oscillations affect the distribution of chemical constituents, such as ozone (O3), water vapor (H2O), nitrous oxide (N2O), and hydrochloric acid (HCl), through the QBO-induced meridional circulation. In the 2015–2016 winter, radiosonde observations revealed an anomaly in the downward propagation of the westerly phase, which was disrupted by the upward displacement of the westerly phase from  ∼  30 hPa up to 15 hPa and the sudden appearance of easterlies at 40 hPa. Such a disruption is unprecedented in the observational record from 1953 to the present. In this study we show the response of trace gases to this QBO disruption using O3, HCl, H2O, and temperature from the Aura Microwave Limb Sounder (MLS) and total ozone measurements from the Solar Backscatter Ultraviolet (SBUV) Merged Ozone Data Set (MOD). Results reveal the development of positive anomalies in stratospheric equatorial O3 and HCl over  ∼  50–30 hPa in May–September of 2016 and a substantial decrease in O3 in the subtropics of both hemispheres. The SBUV observations show near-record low levels of column ozone in the subtropics in 2016, resulting in an increase in the surface UV index during northern summer. Furthermore, cold temperature anomalies near the tropical tropopause result in a global decrease in stratospheric water vapor.

scholarly journals Spatial Coherence of Monsoon Onset over Western and Central Sahel (1950–2000)

2009 ◽  
Vol 22 (5) ◽  
pp. 1313-1324 ◽  
Author(s):  
Romain Marteau ◽  
Vincent Moron ◽  
Nathalie Philippon
Keyword(s):  
Burkina Faso ◽  
Interannual Variability ◽  
Large Scale ◽  
Spatial Coherence ◽  
Daily Rainfall ◽  
Local Scale ◽  
Monsoon Onset ◽  
Onset Date ◽  
Dry Spell

Abstract The spatial coherence of boreal monsoon onset over the western and central Sahel (Senegal, Mali, Burkina Faso) is studied through the analysis of daily rainfall data for 103 stations from 1950 to 2000. Onset date is defined using a local agronomic definition, that is, the first wet day (&gt;1 mm) of 1 or 2 consecutive days receiving at least 20 mm without a 7-day dry spell receiving less than 5 mm in the following 20 days. Changing either the length or the amplitude of the initial wet spell, or both, or the length of the following dry spell modifies the long-term mean of local-scale onset date but has only a weak impact either on its interannual variability or its spatial coherence. Onset date exhibits a seasonal progression from southern Burkina Faso (mid-May) to northwestern Senegal and Saharian edges (early August). Interannual variability of the local-scale onset date does not seem to be strongly spatially coherent. The amount of common or covariant signal across the stations is far weaker than the interstation noise at the interannual time scale. In particular, a systematic spatially consistent advance or delay of the onset is hardly observed across the whole western and central Sahel. In consequence, the seasonal predictability of local-scale onset over the western and central Sahel associated, for example, with large-scale sea surface temperatures, is, at best, weak.

Interannual variability of stratospheric trace gases: The role of extratropical wave driving

2004 ◽  
Vol 130 (602) ◽  
pp. 2459-2474 ◽  
Author(s):  
J. Ma ◽  
D.W. Waugh ◽  
A.R. Douglass ◽  
S.R. Kawa ◽  
P.A. Newman ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Trace Gases ◽  
Stratospheric Trace Gases

scholarly journals Simulation of stratospheric water vapor and trends using three reanalyses

2012 ◽  
Vol 12 (14) ◽  
pp. 6475-6487 ◽  
Author(s):  
M. R. Schoeberl ◽  
A. E. Dessler ◽  
T. Wang
Keyword(s):  
Water Vapor ◽  
Calculation Model ◽  
Vapor Concentration ◽  
The West ◽  
West Pacific ◽  
Stratospheric Water Vapor ◽  
Middle Latitudes ◽  
The Pacific ◽  
Northern High Latitude ◽  
Cold Point

Abstract. The domain-filling, forward trajectory calculation model developed by Schoeberl and Dessler (2011) is extended to the 1979–2010 period. We compare results from NASA's MERRA, NCEP's CFSR, and ECMWF's ERAi reanalyses with HALOE, MLS, and balloon observations. The CFSR based simulation produces a wetter stratosphere than MERRA, and ERAi produces a drier stratosphere than MERRA. We find that ERAi 100 hPa temperatures are cold biased compared to Singapore sondes and MERRA, which explains the ERAi result, and the CFSR grid does not resolve the cold point tropopause, which explains its relatively higher water vapor concentration. The pattern of dehydration locations is also different among the three reanalyses. ERAi dehydration pattern stretches across the Pacific while CFSR and MERRA concentrate dehydration activity in the West Pacific. CSFR and ERAi also show less dehydration activity in the West Pacific Southern Hemisphere than MERRA. The trajectory models' lower northern high latitude stratosphere tends to be dry because too little methane-derived water descends from the middle stratosphere. Using the MLS tropical tape recorder signal, we find that MERRA vertical ascent is 15% too weak while ERAi is 30% too strong. The trajectory model reproduces the observed reduction in the amplitude of the 100-hPa annual cycle in zonal mean water vapor as it propagates to middle latitudes. Finally, consistent with the observations, the models show less than 0.2 ppm decade−1 trend in water vapor both at mid-latitudes and in the tropics.

scholarly journals The relationship between tropospheric wave forcing and tropical lower stratospheric water vapor

2008 ◽  
Vol 8 (3) ◽  
pp. 471-480 ◽  
Author(s):  
S. Dhomse ◽  
M. Weber ◽  
J. Burrows
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Satellite Data ◽  
Planetary Wave ◽  
Wave Activity ◽  
Stratospheric Water Vapor ◽  
Average Decrease ◽  
Eddy Heat Flux ◽  
Sudden Decrease ◽  
Cold Point

Abstract. Using water vapor data from HALOE and SAGE II, an anti-correlation between planetary wave driving (here expressed by the mid-latitude eddy heat flux at 50 hPa added from both hemispheres) and tropical lower stratospheric (TLS) water vapor has been obtained. This appears to be a manifestation of the inter-annual variability of the Brewer-Dobson (BD) circulation strength (the driving of which is generally measured in terms of the mid-latitude eddy heat flux), and hence amount of water vapor entering the stratosphere. Some years such as 1991 and 1997 show, however, a clear departure from the anti-correlation which suggests that the water vapor changes in TLS can not be attributed solely to changes in extratropical planetary wave activity (and its effect on the BD circulation). After 2000 a sudden decrease in lower stratospheric water vapor has been reported in earlier studies based upon satellite data from HALOE, SAGE II and POAM III indicating that the lower stratosphere has become drier since then. This is consistent with a sudden rise in the combined mid-latitude eddy heat flux with nearly equal contribution from both hemispheres as shown here and with the increase in tropical upwelling and decrease in cold point temperatures found by Randel et al. (2006). The low water vapor and enhanced planetary wave activity (in turn strength of the BD circulation) has persisted until the end of the satellite data records. From a multi-variate regression analysis applied to 27 years of NCEP and HadAT2 (radiosonde) temperatures (up to 2005) with contributions from solar cycle, stratospheric aerosols and QBO removed, the enhancement wave driving after 2000 is estimated to contribute up to 0.7 K cooling to the overall TLS temperature change during the period 2001–2005 when compared to the period 1996–2000. NCEP cold point temperature show an average decrease of nearly 0.4 K from changes in the wave driving, which is consistent with observed mean TLS water vapor changes of about −0.2 ppm after 2000.

Understanding the Changes of Stratospheric Water Vapor in Coupled Chemistry–Climate Model Simulations

2008 ◽  
Vol 65 (10) ◽  
pp. 3278-3291 ◽  
Author(s):  
Luke Oman ◽  
Darryn W. Waugh ◽  
Steven Pawson ◽  
Richard S. Stolarski ◽  
J. Eric Nielsen
Keyword(s):  
Water Vapor ◽  
Climate Model ◽  
First Century ◽  
Mixing Ratio ◽  
Stratospheric Water Vapor ◽  
Tropical Tropopause ◽  
Twenty First Century ◽  
Climate Model Simulations ◽  
Cold Point ◽  
Methane Concentrations

Past and future climate simulations from the Goddard Earth Observing System Chemistry–Climate Model (GEOS CCM), with specified boundary conditions for sea surface temperature, sea ice, and trace gas emissions, have been analyzed to assess trends and possible causes of changes in stratospheric water vapor. The simulated distribution of stratospheric water vapor in the 1990s compares well with observations. Changes in the cold point temperatures near the tropical tropopause can explain differences in entry stratospheric water vapor. The average saturation mixing ratio of a 20° latitude by 15° longitude region surrounding the minimum tropical saturation mixing ratio is shown to be a useful diagnostic for entry stratospheric water vapor and does an excellent job reconstructing the annual average entry stratospheric water vapor over the period 1950–2100. The simulated stratospheric water vapor increases over the 50 yr between 1950 and 2000, primarily because of changes in methane concentrations, offset by a slight decrease in tropical cold point temperatures. Stratospheric water vapor is predicted to continue to increase over the twenty-first century, with increasing methane concentrations causing the majority of the trend to midcentury. Small increases in cold point temperature cause increases in the entry water vapor throughout the twenty-first century. The increasing trend in future water vapor is tempered by a decreasing contribution of methane oxidation owing to cooling stratospheric temperatures and by increased tropical upwelling, leading to a near-zero trend for the last 30 yr of the twenty-first century.

Sign in / Sign up

Export Citation Format

Share Document