1. Regimes of temperature distribution change over different surface conditions
This work is now under review in GRL. I will write about it later.
Duan, S. Q., Findell, K. L., Wright, J. S. Three regimes of temperature distribution change over dry land, moist land, and oceanic surfaces, under review, GRL.
2. On using stable water isotope (HDO) to constrain convection
Here in our study, we simulate HDO in a bulk plume model of cumulus convection, and test the sensitivity of HDO to three convective parameters: entrainment/detrainment rate, raindrop re-evaporation fraction, and the distance of the raindrop fall/get-lofted before its re-evaporation.
However, we find that at a given relative humidity, the possible range of HDO is small: its range is comparable to both the measurement uncertainty in the mean tropical profile and the structural uncertainty of a single-column model. Therefore, we conclude that the mean tropical HDO profile is unlikely to add information about free tropospheric convective processes in a bulk-plume framework that cannot already be learned from relative humidity alone. Our message is, if we want to explore physics using water isotope, free tropospheric convective processes is not a good place to apply--look at topical tropopause layer or use isotope for source-seeking in the boundary layer instead.
Duan, S. Q., Wright, J. S., & Romps, D. M. (2018). On the utility (or futility) of using stable water isotopes to constrain the bulk properties of tropical convection. Journal of Advances in Modeling Earth Systems, 10.
3. On rapid intensification of tropical cyclones and its potentially-related environmental factors
Using IBTrACS dataset, we explored the statistics of tropical cyclones (TCs) in six basins recorded by different TC observation centers. We look at time series of the rapid intensification (6-hr increase of max-sustained wind above a cut) and sustained-rapid (24-hr) intensifications of TCs in different basins.
The variance of RI trend among different data centers for a basin is large. Different basins don't show consistent trends neither. We have also interpolated several environmental factors including wind shear, mid-tropospheric humidity, thermodynamic efficiency etc. from JRA-55 reanalysis data to the time and location of the TC records. We are now refining it to using daily reanalysis and enclosing the area of different TC radii. I will update later.
Duan, S. Q. and Wright, J. S.: Variations of rapid and sustained rapid intensification of tropical cyclones in a changing climate, in preparation.
4. Using complex network to construct global monsoon system.
Y. W. Wang, J. S. Wright and S. Q. Duan: A network analysis of the global monsoon system in observations, reanalyses and CMIP5 simulations, to be submitted.
Stable water isotope has a property that heavy isotopes preferably stay in the condensed phase during phase change. This phenomenon is called fractionation. Due to the property of fractionation, water isotope can track water history, and can potentially serve as proxies for physics that we cannot directly measure.
In the recent decade, people are proposing that water isotopes are promising to add constraints on convective physics which are hard to measure and simulate. Satellite measurements of water isotopes and isotope-enabled numerical models are also more developed to lend people better tools to make further explorations.
Sketch of our bulk-plume model of the tropical atmosphere. q and q' denote the mass fractions of H2O and HDO.
𝞭D (HDO) profiles at a given RH value from our model solutions with three free parameters (entrainmet rate, reevaporation fraction and evaporation distance) ranging in their plausible ranges. The colors show the cumulative distribution function of 𝞭D for the subset solutions with that RH value.
The fraction of the rapid intensification occurrences to total intensification records in each year from 1953 to 2012. Each panel is one basin (West Pacific, East Pacific, North Atlantic, North Indian Ocean, South Indian Ocean, South Pacific), and each line in each panel is data collected from one data center for that basin. Line and shading are the same for fraction of the RI occurrences, but just based on 10% and 5% cut defination of RI respectively.