The Role of Optically Thin Liquid Clouds in the 2012 Greenland Ice Sheet Surface Melt Event
1 like131 views
The document details a study by Kyle Nelson on the influence of optically thin liquid clouds on the surface melting of the Greenland Ice Sheet in July 2012. Using satellite data and radiative transfer modeling, it concludes that these clouds significantly increased near-surface temperatures and contributed to the observed melting. The findings suggest a consistent frequency of thin liquid clouds in both July 2011 and 2012, highlighting the need for further research on their role in climate dynamics.
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
The Role of Optically Thin
Liquid Clouds in the 2012
Greenland Ice Sheet
Surface Melt Event
Kyle Nelson
Department of Atmospheric and Oceanic Sciences
Cooperative Institute for Meteorological Satellite Studies
University of Wisconsin-Madison
M.S. Thesis Presentation
August 6, 2014](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-1-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Introduction
• July 2012: new record in surface melt
extent over Greenland Ice Sheet (GIS)
• Observed surface melt over the entire GIS
• Bennartz et al. (2012): Thin, low-level,
liquid clouds occurred very frequently over
Summit, Greenland when melt occurred
– One factor that warmed surface above
freezing](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-2-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Background
Bennartz et al. (2012)](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-3-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Surface Melt Extent
From Nghiem et al. (2012)](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-4-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Research Questions
• What range of cloud optical depth (and LWP)
yields a positive surface radiative forcing?
• What is the sensitivity of cloud base height to
surface radiative forcing?
• What is the frequency of occurrence of thin
liquid clouds over the GIS in 2012?
• Did thin, liquid clouds contribute to the July
2012 surface melt event over the entire GIS?](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-5-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Methods
• Radiative transfer modeling
• Satellite remote sensing
– MYD06 (Col. 5 & 6) Standard Cloud Product
– CALIPSO: CALIOP and IIR
– PATMOS-x MOD02 1.6μm
– Cloud Phase Determination
• ECMWF ERA Interim Reanalysis](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-6-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Cloud Surface Radiative Forcing
ΔFnet = FSW
↓
− FSW
↑
+ FLW
↓
− FLW
↑
FSW,net = FSW
↓
− FSW
↑
FLW,net = FLW
↓
− FLW
↑
CSW =
∂FSW,net
∂a0
Ac
∫ da
CLW =
∂FLW,net
∂a0
Ac
∫ da
Cnet = CSW +CLW
!
• CSW, CLW & CNET are the
shortwave, longwave,
and net cloud forcing
for the surface
• FSW,net & FLW,net are the
net shortwave and
longwave fluxes at the
surface
• Ac is the total cloud
amount
• a is the cloud fraction](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-7-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Solar Zenith Angle vs SRF
Total
Longwave
Shortwave](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-8-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Cloud Base Height vs SRF
2 4 6
−250
−200
−150
−100
−50
0
50
100
Cld Base Ht: 0.5km; SZA = 65
Cld Tau
SurfaceRadiativeForcing
2 4 6
−250
−200
−150
−100
−50
0
50
100
Cld Base Ht: 1km; SZA = 65
Cld Tau
SurfaceRadiativeForcing
2 4 6
−250
−200
−150
−100
−50
0
50
100
Cld Base Ht: 1.5km; SZA = 65
Cld Tau
SurfaceRadiativeForcing
2 4 6
−250
−200
−150
−100
−50
0
50
100
Cld Base Ht: 2km; SZA = 65
Cld Tau
SurfaceRadiativeForcing
2 4 6
−250
−200
−150
−100
−50
0
50
100
Cld Base Ht: 2.5km; SZA = 65
Cld Tau
SurfaceRadiativeForcing
2 4 6
−250
−200
−150
−100
−50
0
50
100
Cld Base Ht: 3km; SZA = 65
Cld Tau
SurfaceRadiativeForcing
Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7
Total
Longwave
Shortwave](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-9-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Summary of Modeled Cloud Forcing
• Determined range of cloud optical depth
and LWP that contribute to surface
warming
– Optical Depth: 1.5-6.5
– Liquid Water Path: 10-40 g/m2
• Assuming 10μm particle effective radius
• Maximum increases with solar zenith angle](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-10-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
MODIS: Moderate Resolution
Imaging Spectroradiometer
• Passive sensor,
measuring radiances
at 36 wavelengths
• Spatial resolutions of
250m to 1km
• Using Aqua-MODIS,
part of NASA’s A-Train
– 1:30pm local equator
crossing time](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-11-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
MYD06 Standard Cloud Product
• Visible and infrared techniques
– Cloud-particle phase (ice vs. water, clouds vs. snow)
– Effective cloud-particle radius
– Cloud optical thickness
• Infrared only technique
– Cloud-top temperature
– Cloud-top height
– Effective emissivity
– Cloud phase (ice vs. water, opaque vs. non-opaque)
– Cloud fraction
• Visible only technique
– Cirrus reflectance](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-12-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Liquid Clouds vs All Clouds (MODIS), July 2012](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-13-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Thin Liquid Clouds vs All Clouds (MODIS), July 2012](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-14-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
MODIS Optical Depth Distribution](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-15-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Liquid Water Path Distribution - MWR](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-16-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Matchups: MODIS/CALIOP/IIR
• Cross-instrument comparison of cloud
optical depth
• Determine which sensor or combination of
data from different sensors produces a
LWP distribution using ground based
observations from the microwave
radiometer at Summit, Greenland](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-17-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
CALIPSO: Cloud-Aerosol Lidar and Infrared
Pathfinder Satellite Observations
• Launched April 28, 2006
• Part of NASA’s A-Train
• CALIPSO combines an active LIDAR
instrument with passive infrared and
visible imagers to diagnose the vertical
structure and properties of thin clouds and
aerosols over the globe.](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-18-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
CALIOP: Cloud-Aerosol Lidar with
Orthogonal Polarization
• CALIOP is a two-wavelength polarization-
sensitive LIDAR that focuses on the vertical
distributions of clouds and aerosols and their
properties
• Vertical resolutions of 30m
• 335m ground-spot spacing
• Level 2 products include
– Aerosol and cloud feature masks
– Aerosol subtype
– Extinction
– Optical depth](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-19-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
IIR: Imaging Infrared Radiometer
• 3 channel imaging radiometer in the thermal
infrared
• Channels at 8.65μm, 10.6μm and 12.05μm
• IIR measurements are combined with the
LIDAR information enabling the retrieval of
the size of ice particles in semi-transparent
clouds.
• The pairing of 10.6μm and 12.05μm channels
is sensitive to small particles, while the
8.65μm and 12.05μm channels are more
sensitive to large particles](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-20-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
CALIOP vs MODIS MYD06](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-21-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
IIR vs MODIS MYD06](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-22-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
IIR vs CALIOP](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-23-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
IIR: Thin Liquid Clouds](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-24-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Alternate Methods Needed
• MODIS Optical Depth
– Standard 2-channel visible retrieval
– Or 1.6μm & 2.1μm
• MODIS Liquid Water Path
– MODIS effective radius & optical depth
• All based on visible or infrared channels
– Challenging over highly reflective and cold
surfaces
• Can we use 1.6μm or 2.1μm channels?](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-25-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Issues: MODIS 2-channel Retrievals](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-26-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Solution: Single Channel Retrieval](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-27-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Solution: PATMOS-x & Look Up Tables
• Pathfinder Atmospheres – Extended
• PATMOS-x MOD02 (Terra)
– Level-1B Calibrated Geolocated Radiances
– Raw 1.6 micron reflectance
– Mapped to a .1°x.1° grid
– One measurement per gridbox per day
• Measurement closest to NADIR
– Used in conjunction with a look-up table
• Work backward from reflectance to optical depth
• Provided by A. Walther](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-28-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
PATMOS-x Gridboxes](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-29-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Sensitivity to Choice of Re - Liquid](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-30-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Was there a significant difference
between July 2011 and July 2012?
• No melting of the GIS interior in July 2011
• Melting over the entire GIS in July 2012](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-31-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Number of Cloudy Days: July 2011 vs 2012](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-32-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Percentage Cloudy – 2°x2° box over Summit
July
2011
July
2012
Calendar Day
1
31
PercentCloudy
100
0
100
0](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-33-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
July
2011
July
2012
Calendar Day
1
31
FractionofThinCloudsvsAllClouds
100
100
0
Fraction of Thin Clouds – 2°x2° at Summit0](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-34-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Cloud Phase Determination
• PATMOS-x MOD02 3.7μm reflectance
• Similar method used by Key & Intrieri
(2000) and Pavolonis & Key (2003) with
AVHRR
• Threshold between ice and liquid cloud
– 3.7μm reflectance >0.07 and
– Cloud top temperature >243K](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-35-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Sensitivity to Choice of Re - Liq](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-36-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Sensitivity to Choice of Re - Ice](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-37-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
July
2011
July
2012
Calendar Day
1
31
FractionofThinLiquidCloudsvsAllClouds
100
100
0
Fraction of Thin Liquid Clouds – 2°x2° at Summit0](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-38-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Frequency of Liquid vs All Cloud – July 2011 vs 2012](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-39-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Frequency of Thin Liq vs All Cloud – July 2011 vs 2012](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-40-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
To Review:
• ICECAPS surface and PATMOS-x satellite
data show a high presence of optically
thin, liquid clouds over the GIS during the
record melt event in July 2012
• In July 2011 and 2012, the frequency of
occurrence and spatial coverage of thin,
liquid clouds was similar](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-41-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Another factor in addition to cloud
cover must have influenced the
surface temperature over the GIS to
push the temperature above freezing](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-42-320.jpg)
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
ECMWF ERA Interim
• Qualitatively assess the general
atmospheric circulation and temperature
advection in the proximity of the GIS
• Monthly Means at select pressure levels
– Geopotential Height
– Temperature
– U- and V-wind](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-43-320.jpg)
![44
[
]
Dept. AOS & CIMSS
Kyle Nelson - UW-Madison](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-44-320.jpg)
![45
[
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-45-320.jpg)
![46
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-46-320.jpg)
![47
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]
Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Conclusions
• Optically thin liquid clouds, regardless of cloud
base height, played a key role in the 2012 and
2011 melt events by increasing near-surface
temperatures across the GIS
• The work of Bennartz et al. (2013) is extended here
by expanding the study domain from a point
observation at Summit to the entirety of
Greenland by leveraging satellite data products
• Radiative transfer modeling showed that these
optically thin clouds warm the surface during the
day regardless of cloud base height](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-47-320.jpg)
![48
[
]
Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Conclusions (cont.)
• Standard cloud products from the MODIS,
CALIOP and IIR sensors did not reliably detect
optically thin, liquid clouds over ice and snow
• Frequency of occurrence and geospatial location
of optically thin liquid clouds over the GIS was
found to be nearly identical in July 2011 and 2012
• With observed melting over almost the entire GIS
in July 2012 (Nghiem 2012), warm air advection is
likely the dominant contributor
– This agrees with the findings of Bennartz et al. (2013)
and Neff et al. (2014)](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-48-320.jpg)
![49
[
]
Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Future Research
• Frequency of thin, liquid clouds in other years
– Significant surface melt
– No surface melt
• Repeat study over the Arctic Ocean to
determine the role of thin, liquid clouds on
the surface energy budget of sea ice
• Expand the time domain to the entire MODIS
satellite record to establish a 15+ year
climatology of location and frequency of
occurrence of optically thin liquid clouds in
the Arctic](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-49-320.jpg)
![50
[
]
Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Acknowledgements
• Jeff Key – Research Advisor
• Steve Ackerman – Academic Advisor
• Ralf Bennartz
• Andy Heidinger
• Andi Walther
• Denis Botambekov
• SSEC PEATE Group
• PATMOS-x Team
• Tristan L’Ecuyer – MS Committee
• Grant Petty – MS Committee
• Mark Kulie
• Erik Gould
This work was supported
by the NOAA Climate
Data Records Program](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-50-320.jpg)
![51
[
]
Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Questions?
Meteorologist | Education & Outreach Specialist
University of Wisconsin-Madison
kyle.nelson@ssec.wisc.edu
@wxkylenelson](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-51-320.jpg)
![52
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Look Up Table Calculations](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-52-320.jpg)
![53
[
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Dept. AOS & CIMSS
Kyle Nelson - UW-Madison
Selected References
• Ackerman, S., R. Holz, R. Frey, E. Eloranta, B. Maddux, and M. McGill (2008): Cloud
detection with MODIS. Part II: Validation, J. Atmos. Oceanic Technol., 25, 1073–1086, doi:
10.1175/2007JTECHA1053.1.
• Bennartz, R. et al. (2013): July 2012 Greenland melt extent enhanced by low-level liquid
clouds. Nature Vol. 496, 83-86, doi: 10.1038/nature12002.
• Curry, J., J. Schramm, W. Rossow and D. Randall, 1996: Overview of Arctic Cloud and
Radiation Characteristics. J. Climate, 9, 1731–1764. doi:
10.1175/1520-0442(1996)009<1731:OOACAR>2.0.CO;2
• Heidinger, A. et al. (2013): The Pathfinder Atmospheres Extended (PATMOS-X) AVHRR
Climate Data Set. BAMS, doi: 10.1175/BAMS-D-12-00246.1 (in press).
• Key, J. and A. Schweiger (1998): Tools for atmospheric radiative transfer: Streamer and
FluxNet. Computers and Geosciences, 24(5), 443-451.
• Key, J. and J. Intrieri (2000): Cloud particle phase determination with the AVHRR. J. Appl.
Meteorol., 39(10), 1797-1805.
• Neff, W. D. et al. (2013): Continental heat anomalies and the extreme melting of the
Greenland ice surface in 2012 and 1889. Journal of Geophys. Research: Atmospheres. doi:
10.1002/2014JD021470 (in press).
• Nghiem, S. V. et al. (2012): The extreme melt across the Greenland Ice Sheet in 2012.
Geophys. Res. Lett. 39, L20502, doi: 10.1029/2012GL053611.
• Shupe, M. D. and J. Intrieri (2004): Cloud radiative forcing of the Arctic surface: the
influence of cloud properties, surface albedo, and solar zenith angle. J. Clim. 17, 616–628.](https://image.slidesharecdn.com/nelsonkyle-msthesistalk-160625211318/85/The-Role-of-Optically-Thin-Liquid-Clouds-in-the-2012-Greenland-Ice-Sheet-Surface-Melt-Event-53-320.jpg)
The Role of Optically Thin Liquid Clouds in the 2012 Greenland Ice Sheet Surface Melt Event
- 1. 1 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison The Role of Optically Thin Liquid Clouds in the 2012 Greenland Ice Sheet Surface Melt Event Kyle Nelson Department of Atmospheric and Oceanic Sciences Cooperative Institute for Meteorological Satellite Studies University of Wisconsin-Madison M.S. Thesis Presentation August 6, 2014
- 2. 2 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Introduction • July 2012: new record in surface melt extent over Greenland Ice Sheet (GIS) • Observed surface melt over the entire GIS • Bennartz et al. (2012): Thin, low-level, liquid clouds occurred very frequently over Summit, Greenland when melt occurred – One factor that warmed surface above freezing
- 3. 3 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Background Bennartz et al. (2012)
- 4. 4 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Surface Melt Extent From Nghiem et al. (2012)
- 5. 5 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Research Questions • What range of cloud optical depth (and LWP) yields a positive surface radiative forcing? • What is the sensitivity of cloud base height to surface radiative forcing? • What is the frequency of occurrence of thin liquid clouds over the GIS in 2012? • Did thin, liquid clouds contribute to the July 2012 surface melt event over the entire GIS?
- 6. 6 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Methods • Radiative transfer modeling • Satellite remote sensing – MYD06 (Col. 5 & 6) Standard Cloud Product – CALIPSO: CALIOP and IIR – PATMOS-x MOD02 1.6μm – Cloud Phase Determination • ECMWF ERA Interim Reanalysis
- 7. 7 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Cloud Surface Radiative Forcing ΔFnet = FSW ↓ − FSW ↑ + FLW ↓ − FLW ↑ FSW,net = FSW ↓ − FSW ↑ FLW,net = FLW ↓ − FLW ↑ CSW = ∂FSW,net ∂a0 Ac ∫ da CLW = ∂FLW,net ∂a0 Ac ∫ da Cnet = CSW +CLW ! • CSW, CLW & CNET are the shortwave, longwave, and net cloud forcing for the surface • FSW,net & FLW,net are the net shortwave and longwave fluxes at the surface • Ac is the total cloud amount • a is the cloud fraction
- 8. 8 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Solar Zenith Angle vs SRF Total Longwave Shortwave
- 9. 9 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Cloud Base Height vs SRF 2 4 6 −250 −200 −150 −100 −50 0 50 100 Cld Base Ht: 0.5km; SZA = 65 Cld Tau SurfaceRadiativeForcing 2 4 6 −250 −200 −150 −100 −50 0 50 100 Cld Base Ht: 1km; SZA = 65 Cld Tau SurfaceRadiativeForcing 2 4 6 −250 −200 −150 −100 −50 0 50 100 Cld Base Ht: 1.5km; SZA = 65 Cld Tau SurfaceRadiativeForcing 2 4 6 −250 −200 −150 −100 −50 0 50 100 Cld Base Ht: 2km; SZA = 65 Cld Tau SurfaceRadiativeForcing 2 4 6 −250 −200 −150 −100 −50 0 50 100 Cld Base Ht: 2.5km; SZA = 65 Cld Tau SurfaceRadiativeForcing 2 4 6 −250 −200 −150 −100 −50 0 50 100 Cld Base Ht: 3km; SZA = 65 Cld Tau SurfaceRadiativeForcing Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7Fresh Snow 4 of 7 Total Longwave Shortwave
- 10. 10 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Summary of Modeled Cloud Forcing • Determined range of cloud optical depth and LWP that contribute to surface warming – Optical Depth: 1.5-6.5 – Liquid Water Path: 10-40 g/m2 • Assuming 10μm particle effective radius • Maximum increases with solar zenith angle
- 11. 11 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison MODIS: Moderate Resolution Imaging Spectroradiometer • Passive sensor, measuring radiances at 36 wavelengths • Spatial resolutions of 250m to 1km • Using Aqua-MODIS, part of NASA’s A-Train – 1:30pm local equator crossing time
- 12. 12 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison MYD06 Standard Cloud Product • Visible and infrared techniques – Cloud-particle phase (ice vs. water, clouds vs. snow) – Effective cloud-particle radius – Cloud optical thickness • Infrared only technique – Cloud-top temperature – Cloud-top height – Effective emissivity – Cloud phase (ice vs. water, opaque vs. non-opaque) – Cloud fraction • Visible only technique – Cirrus reflectance
- 13. 13 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Liquid Clouds vs All Clouds (MODIS), July 2012
- 14. 14 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Thin Liquid Clouds vs All Clouds (MODIS), July 2012
- 15. 15 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison MODIS Optical Depth Distribution
- 16. 16 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Liquid Water Path Distribution - MWR
- 17. 17 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Matchups: MODIS/CALIOP/IIR • Cross-instrument comparison of cloud optical depth • Determine which sensor or combination of data from different sensors produces a LWP distribution using ground based observations from the microwave radiometer at Summit, Greenland
- 18. 18 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison CALIPSO: Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations • Launched April 28, 2006 • Part of NASA’s A-Train • CALIPSO combines an active LIDAR instrument with passive infrared and visible imagers to diagnose the vertical structure and properties of thin clouds and aerosols over the globe.
- 19. 19 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison CALIOP: Cloud-Aerosol Lidar with Orthogonal Polarization • CALIOP is a two-wavelength polarization- sensitive LIDAR that focuses on the vertical distributions of clouds and aerosols and their properties • Vertical resolutions of 30m • 335m ground-spot spacing • Level 2 products include – Aerosol and cloud feature masks – Aerosol subtype – Extinction – Optical depth
- 20. 20 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison IIR: Imaging Infrared Radiometer • 3 channel imaging radiometer in the thermal infrared • Channels at 8.65μm, 10.6μm and 12.05μm • IIR measurements are combined with the LIDAR information enabling the retrieval of the size of ice particles in semi-transparent clouds. • The pairing of 10.6μm and 12.05μm channels is sensitive to small particles, while the 8.65μm and 12.05μm channels are more sensitive to large particles
- 21. 21 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison CALIOP vs MODIS MYD06
- 22. 22 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison IIR vs MODIS MYD06
- 23. 23 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison IIR vs CALIOP
- 24. 24 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison IIR: Thin Liquid Clouds
- 25. 25 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Alternate Methods Needed • MODIS Optical Depth – Standard 2-channel visible retrieval – Or 1.6μm & 2.1μm • MODIS Liquid Water Path – MODIS effective radius & optical depth • All based on visible or infrared channels – Challenging over highly reflective and cold surfaces • Can we use 1.6μm or 2.1μm channels?
- 26. 26 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Issues: MODIS 2-channel Retrievals
- 27. 27 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Solution: Single Channel Retrieval
- 28. 28 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Solution: PATMOS-x & Look Up Tables • Pathfinder Atmospheres – Extended • PATMOS-x MOD02 (Terra) – Level-1B Calibrated Geolocated Radiances – Raw 1.6 micron reflectance – Mapped to a .1°x.1° grid – One measurement per gridbox per day • Measurement closest to NADIR – Used in conjunction with a look-up table • Work backward from reflectance to optical depth • Provided by A. Walther
- 29. 29 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison PATMOS-x Gridboxes
- 30. 30 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Sensitivity to Choice of Re - Liquid
- 31. 31 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Was there a significant difference between July 2011 and July 2012? • No melting of the GIS interior in July 2011 • Melting over the entire GIS in July 2012
- 32. 32 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Number of Cloudy Days: July 2011 vs 2012
- 33. 33 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Percentage Cloudy – 2°x2° box over Summit July 2011 July 2012 Calendar Day 1 31 PercentCloudy 100 0 100 0
- 34. 34 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison July 2011 July 2012 Calendar Day 1 31 FractionofThinCloudsvsAllClouds 100 100 0 Fraction of Thin Clouds – 2°x2° at Summit0
- 35. 35 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Cloud Phase Determination • PATMOS-x MOD02 3.7μm reflectance • Similar method used by Key & Intrieri (2000) and Pavolonis & Key (2003) with AVHRR • Threshold between ice and liquid cloud – 3.7μm reflectance >0.07 and – Cloud top temperature >243K
- 36. 36 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Sensitivity to Choice of Re - Liq
- 37. 37 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Sensitivity to Choice of Re - Ice
- 38. 38 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison July 2011 July 2012 Calendar Day 1 31 FractionofThinLiquidCloudsvsAllClouds 100 100 0 Fraction of Thin Liquid Clouds – 2°x2° at Summit0
- 39. 39 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Frequency of Liquid vs All Cloud – July 2011 vs 2012
- 40. 40 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Frequency of Thin Liq vs All Cloud – July 2011 vs 2012
- 41. 41 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison To Review: • ICECAPS surface and PATMOS-x satellite data show a high presence of optically thin, liquid clouds over the GIS during the record melt event in July 2012 • In July 2011 and 2012, the frequency of occurrence and spatial coverage of thin, liquid clouds was similar
- 42. 42 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Another factor in addition to cloud cover must have influenced the surface temperature over the GIS to push the temperature above freezing
- 43. 43 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison ECMWF ERA Interim • Qualitatively assess the general atmospheric circulation and temperature advection in the proximity of the GIS • Monthly Means at select pressure levels – Geopotential Height – Temperature – U- and V-wind
- 44. 44 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison
- 45. 45 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison
- 46. 46 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison
- 47. 47 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Conclusions • Optically thin liquid clouds, regardless of cloud base height, played a key role in the 2012 and 2011 melt events by increasing near-surface temperatures across the GIS • The work of Bennartz et al. (2013) is extended here by expanding the study domain from a point observation at Summit to the entirety of Greenland by leveraging satellite data products • Radiative transfer modeling showed that these optically thin clouds warm the surface during the day regardless of cloud base height
- 48. 48 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Conclusions (cont.) • Standard cloud products from the MODIS, CALIOP and IIR sensors did not reliably detect optically thin, liquid clouds over ice and snow • Frequency of occurrence and geospatial location of optically thin liquid clouds over the GIS was found to be nearly identical in July 2011 and 2012 • With observed melting over almost the entire GIS in July 2012 (Nghiem 2012), warm air advection is likely the dominant contributor – This agrees with the findings of Bennartz et al. (2013) and Neff et al. (2014)
- 49. 49 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Future Research • Frequency of thin, liquid clouds in other years – Significant surface melt – No surface melt • Repeat study over the Arctic Ocean to determine the role of thin, liquid clouds on the surface energy budget of sea ice • Expand the time domain to the entire MODIS satellite record to establish a 15+ year climatology of location and frequency of occurrence of optically thin liquid clouds in the Arctic
- 50. 50 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Acknowledgements • Jeff Key – Research Advisor • Steve Ackerman – Academic Advisor • Ralf Bennartz • Andy Heidinger • Andi Walther • Denis Botambekov • SSEC PEATE Group • PATMOS-x Team • Tristan L’Ecuyer – MS Committee • Grant Petty – MS Committee • Mark Kulie • Erik Gould This work was supported by the NOAA Climate Data Records Program
- 51. 51 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Questions? Meteorologist | Education & Outreach Specialist University of Wisconsin-Madison [email protected] @wxkylenelson
- 52. 52 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Look Up Table Calculations
- 53. 53 [ ] Dept. AOS & CIMSS Kyle Nelson - UW-Madison Selected References • Ackerman, S., R. Holz, R. Frey, E. Eloranta, B. Maddux, and M. McGill (2008): Cloud detection with MODIS. Part II: Validation, J. Atmos. Oceanic Technol., 25, 1073–1086, doi: 10.1175/2007JTECHA1053.1. • Bennartz, R. et al. (2013): July 2012 Greenland melt extent enhanced by low-level liquid clouds. Nature Vol. 496, 83-86, doi: 10.1038/nature12002. • Curry, J., J. Schramm, W. Rossow and D. Randall, 1996: Overview of Arctic Cloud and Radiation Characteristics. J. Climate, 9, 1731–1764. doi: 10.1175/1520-0442(1996)009<1731:OOACAR>2.0.CO;2 • Heidinger, A. et al. (2013): The Pathfinder Atmospheres Extended (PATMOS-X) AVHRR Climate Data Set. BAMS, doi: 10.1175/BAMS-D-12-00246.1 (in press). • Key, J. and A. Schweiger (1998): Tools for atmospheric radiative transfer: Streamer and FluxNet. Computers and Geosciences, 24(5), 443-451. • Key, J. and J. Intrieri (2000): Cloud particle phase determination with the AVHRR. J. Appl. Meteorol., 39(10), 1797-1805. • Neff, W. D. et al. (2013): Continental heat anomalies and the extreme melting of the Greenland ice surface in 2012 and 1889. Journal of Geophys. Research: Atmospheres. doi: 10.1002/2014JD021470 (in press). • Nghiem, S. V. et al. (2012): The extreme melt across the Greenland Ice Sheet in 2012. Geophys. Res. Lett. 39, L20502, doi: 10.1029/2012GL053611. • Shupe, M. D. and J. Intrieri (2004): Cloud radiative forcing of the Arctic surface: the influence of cloud properties, surface albedo, and solar zenith angle. J. Clim. 17, 616–628.