Menglin JinMenglin JinDepartment of Atmospheric & Oceanic ScienceDepartment of Atmospheric & Oceanic ScienceUniversity of Maryland, College parkUniversity of Maryland, College park

Observed Land Impacts on Observed Land Impacts on Clouds, Water Vapor, and Rainfall at Clouds, Water Vapor, and Rainfall at

Continental ScalesContinental Scales

Michael D. KingMichael D. KingEarth-Sun Exploration Division, Earth-Sun Exploration Division, NASA Goddard Space Flight Center, NASA Goddard Space Flight Center, Greenbelt, MarylandGreenbelt, Maryland

January5, 2006January5, 2006MODIS Science Team MeetingMODIS Science Team Meeting

How do the continents affect large-scale hydrological cycles?

How important can one continent be to the climate system?

1. Scientific Questions:

2. Data Sets Used:•5-years of NASA Terra MODIS observations; •3-year NASA Aqua MODIS observations;•TRMM observations;•Global Precipitation Climatology Project (GPCP); global precipitation analysis; •NCEP reanalysis;to assess the land impacts on clouds, rainfall, and water vapor at continental scales.

3. Why Continental Scale? - Importance of Continental Scale

• Features at continental scale is index of land impact on climate

• Continental scale is critical in testing the accuracy of GCM Coe, M.T. (2000, J. of Climate),

Jin, M. et al. (1997 J. of Climate)

• Few studies focus on continental scale

With knowledge of local/global features, can we extend to know the features at continental scale?

Answer: No, as climate system is nonlinear

Knowing other scales cannot ensure understanding at continental scale

Cloud Features at Various Spatial Scales

5 year averaged Cloud Optical Thickness

Land Impacts on Cloud Optical ThicknessLand Impacts on Cloud Optical Thickness

Continent Impacts on Cloud Optical Thickness

Probability Density FunctionProbability Density Function

land

ocean

Temporal Variations of PDF for Cloud Optical Thickness

MODIS Cloud Fraction Daytime

Ocean OnlyOcean Only (90°N-90°S, 180°E-180°W) (90°N-90°S, 180°E-180°W)

LandLandAverage 0.693 0.536

Ocean Land

Seasonal range 0.04 0.11

MODIS Cloud Fraction Daytime

MODIS Cloud Fraction Daytime

Ocean OnlyOcean Only

Land OnlyLand Only

MODIS Cloud Effective Radius

Ice clouds

Liquid water clouds

Cirrus FractionCirrus Fraction

Land enlarges seasonality of cirrus fractionLand enlarges seasonality of cirrus fraction

Column Water Vapor

Land enlarges seasonality, and reduces the absolute value of water vapor

MODIS Column Water VaporMODIS Column Water Vapor NCEP Reanalysis Water VaporNCEP Reanalysis Water Vapor

MODIS is valuable to evaluate Reanalysis and model simulationsMODIS is valuable to evaluate Reanalysis and model simulations

Probability Density FunctionProbability Density Function

Monthly rainfall forNorthern Hemisphere, North America,and Eurasia.

GPCP Data

Continents have larger rainfall seasonality

SummarySummary SummarySummary

• MODIS observations are extremely useful in understanding land MODIS observations are extremely useful in understanding land impacts on global climate. impacts on global climate.

• Land mass enhances seasonality of clouds, water vapor, and Land mass enhances seasonality of clouds, water vapor, and rainfall. rainfall.

• Land decreases the liquid cloud effective radius, cloud fraction, Land decreases the liquid cloud effective radius, cloud fraction, and water vapor.and water vapor.

• Need More Work on providing Need More Work on providing insightful statisticsinsightful statistics

physical interpretation physical interpretation