
NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
Recipient: |
|
Initial Amendment Date: | April 4, 2013 |
Latest Amendment Date: | April 4, 2013 |
Award Number: | 1261948 |
Award Instrument: | Standard Grant |
Program Manager: |
Eric DeWeaver
edeweave@nsf.gov (703)292-8527 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
Start Date: | April 1, 2013 |
End Date: | March 31, 2017 (Estimated) |
Total Intended Award Amount: | $259,112.00 |
Total Awarded Amount to Date: | $259,112.00 |
Funds Obligated to Date: |
|
History of Investigator: |
|
Recipient Sponsored Research Office: |
400 HARVEY MITCHELL PKY S STE 300 COLLEGE STATION TX US 77845-4375 (979)862-6777 |
Sponsor Congressional District: |
|
Primary Place of Performance: |
TAMU 3150 College Station TX US 77843-3150 |
Primary Place of
Performance Congressional District: |
|
Unique Entity Identifier (UEI): |
|
Parent UEI: |
|
NSF Program(s): | Climate & Large-Scale Dynamics |
Primary Program Source: |
|
Program Reference Code(s): |
|
Program Element Code(s): |
|
Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.050 |
ABSTRACT
This project seeks to understand changes in tropical stratospheric water vapor seen in observations and in model simulations of future climate change. Simulations of future climate consistently show an increasing trend in tropical stratospheric water vapor due to greenhouse gas increases, but satellite data since the 1980s show interannual and decadal variability but little trend. In addition, comparison of monthly stratospheric water vapor and 100hPa heating rate are negatively correlated in observational data, but positively correlated in future climate simulations. Negative correlations are expected if changes in water vapor and heating rates are linked to variations in the Brewer-Dobson circulation, as a stronger BD circulation is associated with stronger tropical heating (i.e. stronger diabatic upwelling) and colder tropical stratospheric temperatures. But future climate simulations show increases in both water vapor and the strength of the BD circulation. Moreover, increases in surface temperature are expected to produce increases in stratospheric water vapor, but surface temperatures rose over the observed record while tropical stratospheric water vapor did not. This project uses a suite of models including a domain-filling trajectory model, the Whole Atmosphere Community Climate Model (WACCM), and a one-dimensional radiative transfer model, to understand the underlying processes responsible for the changes in observed and simulated water vapor changes.
The work has broader impacts due to the climatic effects of stratospheric water vapor, and the relationship between stratospheric ozone and water vapor. In addition, the PI will conduct outreach to general audiences through new-media outlets, thereby working to increase public understanding of the phenomena addressed in this research. The project also supports and trains a graduate student, thereby providing for the development of the scientific workforce in this research area.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This proposal is focused on analyzing and understanding the mechanisms that control stratospheric water vapor and testing whether climate models appropriately simulate them. Much of our work focused on demonstrating the existence and estimating the strenght of a stratospheric water vapor feedback, where a warming climate increases stratospheric water vapor, which in turn further warms the surface. While it had been previously speculated, ours was the first analysis to demonstrate its existence in observations (Dessler et al., PNAS, 2013). We leveraged this work to explain the variability of water vapor over the last few decades (Dessler et al., JGR, 2014). That paper showed that there was little long-term trend in stratospheric water vapor; previous suggestions that a trend existed has mistakenly confused short term variability for long-term behavior. That paper also yielded an estimate of the impact of Mt. Pinatubo on the humidity of the stratosphere. Finally, we studied the cause of long-term trends in two climate models. The conventional wisdom is that these trends are caused by a warming tropopause. We found that, while a warming tropopause is indeed a primary contributor, much of the trend is due to an increase in convectively lofted ice evaporating in the lower stratosphere (Dessler et al., GRL, 2016).
In addition to these major results, we also published several papers exploring particular mechanisms or phenomena of interest. This includes the impact of small-scale, unresolved temperature fluctuations (Wang et al., 2015), transport of O3 and CO in the TTL (Wang et al, 2014), the details of convective ice injection (Yu et al., in prep), and the details of how the the seasonal cycle is generated (Wang et al., in prep). These studies were written by graduate students supported by this grant, contributing to the education of future members of the atmospheric sciences community.
Last Modified: 04/07/2017
Modified by: Andrew E Dessler
Please report errors in award information by writing to: awardsearch@nsf.gov.