satellite and tower data reveal unique climate o ver the southern sierra nevada
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Satellite and Tower Data Reveal Unique Climate O ver the Southern Sierra Nevada. Eric Waller Department of Environmental Science, Policy, and Management University of California, Berkeley SSCZO Annual Meeting Fresno, CA 8/4/14. MODIS Aqua (~1 PM) April Cloud Frequency, 2003-2011. - PowerPoint PPT PresentationTRANSCRIPT
Satellite and Tower Data Reveal Unique Climate Over the Southern Sierra Nevada
Eric WallerDepartment of Environmental Science, Policy, and Management
University of California, Berkeley
SSCZO Annual MeetingFresno, CA
8/4/14
MODIS Aqua (~1 PM)April Cloud Frequency,2003-2011
Average MODIS (Aqua) 2012 Diel Land Surface Temperature Range (Day – Night)
{Clear Sky Days!}
Δ 0C
Average Annual MODIS Diel Land Surface Temperature Range (C)
Aver
age
Annu
al M
OD
IS
Clou
d Fr
eque
ncy
(%)
R2 = 0.58Sequoia Points
Other Sierra NevadaPoints
405 meters
1160 meters
2015 meters
2700 meters
NoonFebruaryMarch
April
January
Average ½ Hourly Temperature by Month: 2015 meter site
Noon
Average ½ Hourly Dew Point Temperature by Month: 2015 meter site
Afternoonpeaks
Noon
Average ½ Hourly Relative Humidity by Month: 2015 meter site
Noon
Average ½ Hourly Relative Humidity by Month: 2015 m site, Clear Afternoons
Noon
Average ½ Hourly Relative Humidity for 4 Towers: April
Noon
No daytime warm-up at tower at 2015 meters
Average ½ Hourly Temperature for 4 Towers: April
°C
October minus April maximum temperature (California mountains unusually cold in April!)
Where’s this cold spring air coming from?
-still cold North Pacific
-Pacific high migrating north: winds/weather generally coming from
northwest rather than the west (confirmed by NCEP/NARR data)
-meridional flow: cutoff or closed lows
Regional and local conditions that favor Giant Sequoia:
-Low wind-Frequent high afternoon humidity and cloud cover-Late spring shift in precipitation -Cold spring storms: late spring shift in snowfall
A lot of these factors that could be beneficial to Sequoia could be reducing sublimation substantially as well.
A need for better Sierra-wide mapping of sublimation?
This area also has among the lowest average wind speeds in the world.
Giant Sequoia is responding to some combination of these climatic features – basically outcompeting other species in this unique climate regime.
In sum:
Unusually cloudy, particularly on spring afternoons (strongest predictor of Giant Sequoia distribution)
But there are a lot of (cor)related variables:• Unusually low spring temperatures (April COLDER than January)• Low diel temperature range (so spring afternoons especially cool)• Afternoon peaks in water vapor
• Highest relative humidity in the afternoon • Lowest vapor pressure deficit in the afternoon
• Extremely low wind
Much of this unusual behavior only evident at height
NOT PRE-DAWN!
Targeted climatic measurements above the surface
Daily patterns of temperature and humidity (rather than just min and max or average)
Extra measurements: wind, radiation (direct and diffuse), etc.
Relate to plant phyisological ecology and productivity
Some extra factors to consider in assessing climates