Funded by NASA Research Opportunities in Space and Earth Sciences (ROSES), 2008-2011.

Motivation:

Objectives:

Highlight:

Funded by NOAA Climate Prediction Program for the Americas (CPPA), 2006-2009.

Motivation:
Summer precipitation in the Southeast United States (SE US) is dominated by tropical-like convection driven by thermodynamic instability, thus can be highly sensitive to land surface fluxes.  However, very different land surface influences on rainfall in this region have been suggested among previous studies. The study aims to determine the relative role of land surface processes and large-scale moisture transport in control the onset and amount of warm seasonal precipitation over SE US.

Objectives:
(1) To explore the influence of pre-summer soil moisture conditions, rainfall and moisture transport from Gulf of Mexico on the land surface fluxes and increase of tropical-like thermodynamic driven precipitation in summer over SE US;
(2) To determine whether soil moisture feedbacks can prolong or amplify summer drought;
(3) To clarify the remote oceanic and atmospheric forcings for persistent summer droughts and wet anomalies in SE US.

Highlight:

Figure 1. Time series of rainfall anomalies averaged over the Southeast (25°-36.5°N, 76°-91°W). Indicating an intensification of summer rainfall variability after 1976.

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Funded by NASA Research Opportunities in Space and Earth Sciences (ROSES), 2006-2009.

Motivation:
Water resources depend on the amount, as well as the distribution of the precipitation over land, which largely relies on moisture transport from oceans. It is found that oceanic moisture transport determines the wet season onset and supplies moisture for wet season rainfall over the Amazon. The latent heat of Amazonian rainfall can significantly influence ocean surface winds and the ITCZ over the Northern and tropical Atlantic Ocean. The amount of oceanic moisture that will precipitate over land and will contribute to river discharge significantly depends on land surface/vegetation processes.  These hydrological process link the climate variability over South America and the tropical Atlantic. The advances in QuikSCAT and other satellite and in situ observations and our previous results enable us to apply QuikSCAT and SeaWinds backscatter (σ_o) and ocean surface winds and their non-standard products to the hydrological coupling between land and ocean.

Objectives:
(1) Determine the influence of oceanic moisture transport on the South American monsoon onset, demise, and rainfall pattern, and their interannual variations using the QuikSCAT moisture transport product;
(2) Use high resolution σ_o and in situ observations over the Amazon to identify the signals related to canopy wetness, to characterize its occurrence and spatial pattern, and to explore joint use of tandem QuikSCAT/SeaWinds σ_o and MODIS to improve the observations of vegetation in cloudy and rainy conditions and its seasonality over the Amazon;
(3) Examine the influence of South American rainfall on the interannual variations over the tropical Atlantic during boreal spring, particularly on the onset of Atlantic Nino and inter-hemispheric mode of SST anomalies in that region.

Highlight:

Figure 2: left panel: QuikSCAT descending egg- SIR- σ_o (horizontal axis) vs. MODIS NDVI (vertical axis) for the Southern Amazon and vicinity for three days of dry season during 2000. Right panel: MODIS NDVI (horizontal axis) vs. LAI (vertical axis).

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Funded by NASA in support of Aura, 2006-2009.

Motivation:
Aura MLS provides continuous measurements from 82°S to 82°N, a key improvement in temporal sampling for the study of extratropical water vapor and related atmospheric processes. Its measurements penetrate down to middle troposphere (500 hPa) and extend up into the stratosphere, enabling us to simultaneously diagnose the upward transport along fronts and stratosphere dry air intrusion associated with equatorward intrusion of the extratropical disturbances and Rossby wave breaking (Waugh and Fonatsu 2003).  Aura MLS measurements also overlap with the period of TRMM PR, MODIS and AIRS observations. The combination of these observations offers us an unprecedented opportunity to examine the influence of vertical and microphysical structures of deep tropospheric convection and cirrus clouds on the upper troposphere water vapor and cross tropopause transport.

Objectives:
(1) Understand the influence of vertical and microphysical structures of the convection on the water vapor in local and downstream upper troposphere; examine the effect of monsoon variability and human induced environmental changes (such as drought and biomass burning) on convective transport of water vapor.
(2) Investigate the relative contributions of tropical convective outflow, local convective transport and isentropic intrusions of the stratosphere air associated with Rossby wave breaking to changes of water vapor in the subtropical upper troposphere.
(3) Test the relative importance of convective versus isentropic transport to the fast exchange between the troposphere and extratropical lowermost stratosphere;
(4) Optimally extend the Aura observations by synergetic use of multiple satellite observations and more effectively use these observations to support Aura modeling and assimilation activities.

Figure 3. Monthly mean ice cloud effective radius for July 1999 derived from MODIS for the Asian monsoon region.  Unit: mm

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PI: "Investigating the Influences of Vegetation, Biomass Burning, Clouds on WetSeason Onset over the Amazon Using Terra, Aqua in Conjunction with In Situ and Other Satellite Data Sets," Earth Science Enterprise (ESE), NASA, 2004-2006.

PI: "Diagnosis of the Mechanisms that Control the Seasonal Geographic Advancement and Retreat of the Rainy Areas over South America," Office of Global Program, NOAA, June 2003-July 2006.

PI: "Diagnostics of interannual variation of rainfall over South America and its interaction with atmospheric circulation over North Atlantic," to Division of Climate, Modeling, Analysis and Prediction, NSF, February 2003-January 2005.

PI: "Investigating the influences of changes in convection types and boundary layer clouds on intraseasonal to interannual variations of precipitation over Amazon and on the tropical upper troposphere water vapor using ESE multi-satellite sensors," the Global Water and Energy Cycle Research Analysis, Office of Earth Sciences, NASA, 2002-2005.

PI: "Characterize Mesoscale Convective Complex systems over Tibet Plateau using multiple satellite observations," CNSF, 2005-2007.

PI: "Investigating the influence of ocean and land surface vegetation on the seasonal and interannual variations of precipitation over Amazon through use of SeaWinds scatterometer data and atmospheric model simulations," Ocean Vector Winds Science Team (OVWST) of NASA Mission to Planet Earth and Earth Observing System Science, 2000-2005.

Co-I: "Dynamics and predictability of rainy season onset and demise for South America in observations and GCM simulations," NOAA CPPA, of 2004-2007.

Co-I: "Characteristics and predictability of the extratropical atmospheric response to the ENSO cycle," Office of Global Programs, NOAA , 2001-2004.

Co-I: "Land-ocean-atmosphere interaction: mechanisms for the seasonal variations in precipitation over tropical land," NSF, 1998-2003.

PI: "What controls the seasonal and interannual variations of precipitation in tropical South America? - A combined observational and climate model study of ocean-atmosphere-land coupling for improving climate prediction," Office of Global Programs, NOAA, 1998-2001.

PI: "Using UARS MLS to investigate the impacts of troposphere convection and planetary-scale and synoptic waves on the lower stratosphere water vapor in the tropics and mid-latitudes," NASA Mission to Planet Earth Upper Atmosphere Research Satellite Science Investigator Program, 1998-2000.

PI: "The role of atmosphere-land-ocean coupling in determining clouds, precipitation and water vapor," NASA Mission To Planet Earth New Investigator Program, 1996-1999.

PI: "A Career Development Plan with Primary Emphasis on a Process Study of Upper Troposphere Water Vapor in Midlatitude," NSF Early Career Development Program, 1995-1998.

PI: "Use of Satellite and In situ Meteorological Data to Improve the Climate Predictions in the Equatorial and South America Through a Better Understanding of Amazon Convection," Office of Global Programs, NOAA, April 1, 1995-March 31, 1997.

Co-I: "Land-Atmosphere Interactions - A Core Program in Support of Community Climate System Modeling," NSF, January 1, 1995-December 31, 1997.

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