The role of climate change on the ecosystems of the Luquillo LTER Craig A. Ramseyer & Thomas L. Mote University of Georgia

NE PR Climate Change Scenario Modeling Source: USGS Landsat

WRFG_NCEP Current (1981 – 1995) “Significant Severe Environments” WRFG_CCSM Future (2041 – 2065) Past Experience with CC Modeling Source: Gensini, V., Ramseyer, C., Mote, TL (in review, IJOC)

Climate Downscaling Dynamic downscaling ◦ Use of global climate models (GCMs) as boundary conditions for higher resolution regional climate model.  Nested grid(s) ◦ Able to resolve regional scale meteorological phenomena leading to more representative projections at a local level.

Climate Downscaling Source: MMM UCAR

Climate Impacts on TMCF Lowland deforestation results in warmer, drier air upwind of cloud forests and thus influences base heights of cloud (Nair et al. 2003). Climate change will affect the distribution of potential locations for cloud forests, even force them out of existence (Still et al. 1999). Under doubled CO 2, RH surface shifts upwards (inferring elevated cloud bases) and reduces TMCF cloud contact (Still et al. 1999).

Climate Impacts on TMCF Source: Still et al Simulating the effects of climate change on tropical montane cloud forests. Nature 398, 608 – 610.

Potential Research Questions How do precipitation, precipitation extremes (drought), and other climate variables change spatially and orographically in NE PR under future IPCC emissions scenarios and LULC scenarios?

Potential Research Questions Can we identify and resolve climate proxies for tropical montane cloud forest (TMCF) in the model? Is there a spatial shift in the climate proxies?

Importance of Study The Luquillo LTER and the surrounding area exhibits a steep precipitation gradient that hosts a range of ecosystems. Rainfall changes are likely to be significant and potentially more important (ecologically and hydrologically) than temperature change for TMCFs (Mulligan and Burk 2005; Foster 2010). Source: NWS SJU

Importance of Study “GCM rainfall projections over tropical mountains are still highly uncertain.” (Mulligan, 2010) “More realistic analyses of TMCF sites will require… coupled mesoscale regional models that better resolve the steep topography and local land use changes at most TMCF sites.” (Still et al. 1999)

Proposed Study Run GCM (e.g. CCSM, HadCM3) forced with IPCC emissions scenarios (LULC scenarios) Embed a nested high resolution grid over NE PR and run RCM (WRF). ◦ Potential output variables used to infer TMCF: accumulated precipitation, heat flux, cloud bottom/top height, RH, LCL... Any others? ◦ Historical run  Validate with observations/remote sensing techniques

Deliverables High resolution GIS maps of several climatological/meteorological variables at various timescales. ◦ Entire future period, seasonal, monthly Analysis of distributions projected by WRF output. Analysis of shifts in climate proxies that are used to infer TMCF.

Saharan Dust Precipitation Impacts Forest fire aerosols alter clouds ability to precipitate and microphysical properties of clouds (Ramseyer and Mote, in review Atmos. Env.).

Aerosol-Cloud-Precipitation Processes Clouds forming within Saharan dust contain small droplets and produce little precipitation (Rosenfeld et al. 2001). Rosenfeld et al. 2001: Aerosol map for the 1 st of March 2000 (left) and 5 th of March Dust aerosols in green, smoke in blue, sulfates in yellow, and black contours smoke and dust.

Aerosol-Cloud-Precipitation Processes Saharan dust particles as cloud condensation nuclei and ice nuclei impact droplet size and albedo in small clouds and ice formation in deep, convective clouds (Twohy et al. 2009). Saharan dust impacts the Caribbean mid summer drought (MSD) and has a stronger signal than other climate forcings (e.g. NAO, ITCZ). (Angeles et al. 2010).

Saharan Dust Mean MODIS AOD for 7/11/2012 – 7/19/2012 (Source: LAADS Web)

Saharan Dust Approaching PR

Future Work How does Saharan dust effect precipitation, drought events, and cloud processes in Puerto Rico? Is the amount (frequency of events, aerosol loads) of Saharan dust increasing in PR? How will these processes change in a changing climate?

Proposed Study Develop a climatology of Saharan dust in PR using MODIS AOD data and/or observed data. Assess the current impact of dust on precipitation and drought events by analyzing long term trends between AOD and precipitation, cloud particle radius, etc. Model future impacts of Saharan dust on precipitation/clouds under a suite of increased dust scenarios.

Questions? Comments?