Upload
others
View
0
Download
0
Embed Size (px)
Citation preview
1 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
AIM science results and their significance for PMC long-term change studies
By
James M. Russell III and Pingping Rong 2nd CAWSES Workshop
LASP Science Building, Boulder, CO
May 3 - 4, 2012
2 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
AIM was launched from VAFB by a Pegasus XL rocket
Launched April 25, 2007 at 1:26:03 PDT
Near perfect 600 km orbit - 596 km perigee, 601 km apogee - Ascending node equatorial crossing time only 47 seconds off
3 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SOFIE: Solar Occultation for Ice Experiment
- A 16-band differential absorption radiometer (UV to IR) to simultaneously measure cloud properties, the PMC environment and cosmic smoke
CIPS: Cloud Imaging and Particle Size Experiment
- Four CCD cameras; image PMCs at λ = 0.265 µm - 2000 x 2000 element array with 5km x 5km resolution
AIM has two operating instruments
4 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Two questions are addressed in this presentation:
1. What is the main driver of long-term bright PMC increases measured by SBUV? Is it temperature H2O, or other causes?
2. Is the number of clouds increasing at low latitudes in the 40O to 60O range?
5 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Albedo: DeLand et al. [2007] Frequency: Shettle et al. [2009]
PMC brightness and frequency increases over the last 27 years from SBUV data
Provided by Matt DeLand
6 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
What is the main driver of long-term increases in in bright PMCs measured by SBUV? Is it T, H2O or other causes?
Approach: Examine SOFIE T, H2O and PMC changes during the season
Use the Hervig et al. (2009) 0-D water/ice model to analyze changes
7 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
AIM SOFIE data show that T is in dominant control at the season start and end. H2O is in control during the season.
Northern Hemisphere Rong et al., 2011
PMC Workshop, Dec 2009 8
Log-
Pres
sure
Alti
tude
(km
)
WACCM Estmated Temperature and H2O trends Arctic (70°N, -90°) 2000-2050 (JJA)
Large trend in H2O, small trend in T near summer mesopause Rolando Garcia, December, 2009
PMC effect on H2O is not included
20
20
20
-2 -1 0 1 2 k/decade %/decade
-5 0 5 10 15
100
80
60
40
20
Alti
tude
(km
)
ΔT Δ H2O
9 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Is there any temporal trend in the occurrence of low latitude PMCs?
10 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Low latitude NLC observations All occurred during or after 1999
US towns where NLCs were recently sighted:
- Bellingham, WA 46.8N - Glen Ullin, ND 46.8N - Portland, OR 45.5N - Twin Falls, ID 42.6N - Logan, UT 41.7N - Boulder, CO 40.2N - McGuire, NJ 40.1N
• • •
• • •
•
•
• •
All low latitude sightings occured in or after 1999
Orange
50N
60N
11 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
NLCs observed over Omaha, NE (410N) on July 14, 2009 Mike Hollingshead
12 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
AIM CIPS observed low latitude PMCs on July 15, 2009
13 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Approach: Create clouds using the following:
- 0-D model by Hervig et al. (2009)
- SABER temperatures for 2002 to 2011 with an MLS H2O climatology for the
PMC season
- MLS temperatures and H2O for 2005 to 2011 Analyze the numbers and temporal changes in clouds as a function of latitude over the 10 year period from 2002 through 2011
Low latitude PMC data sets used and analysis approach
14 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Two H2O fields are used in 0-D modeling - the MLS mean and maximum
Steps to obtain the H2O fields:
1. 5° latitude bands
2. For each band calculate the mean or select the max
of all events for a given day and given year
3. Calculate the average for each band for each day for both the maximum and mean cases over the period 2005 - 2011
MLS H2O fields at 84 km
15 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SABER Max H2O
Sharply defined by PSAT, not very sensitive to H2O
16 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SABER Mean H2O
Sharply defined by PSAT, not very sensitive to H2O
17 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SABER derived clouds show a robust upward trend
MLS derived clouds show similar changes
SABER 84km cloud number trends for max H2O
Lower lats
18 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SABER derived clouds show a robust upward trend
For latitudes > 55N, both SABER and MLS derived clouds show no trend
SABER 84km cloud number trends for max H2O
Lower lats Higher lats Higher lats
19 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SABER 84 km temperature trends for 2002 - 2011
Downward T trend drives cloud increases for 40 – 55N
20 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SABER 84 km temperature trends for 2002 - 2011
In the saturated condition > 55N, T variation no longer controls cloud frequency, which is close to 100%.
Downward T trend drives cloud increases for 40 – 55N
21 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Brightest PMCs, mice>60 ng/m3 MLS H2O trend
MLS 84 km H2O and bright PMCs trends for 2005 - 2011
22 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
All PMCs, mice>0.15 ng/m3 MLS H2O trend
MLS 84 km H2O and all PMCs trends for 2005 - 2011
23 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Does 0-D model bright PMCs derived using MLS T, H2O agree with SBUV changes?
SBUV Long-term changes
[Shettle et al., 2009]
24 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Brightest clouds, mice>60 ng/m3
Both 0-D model bright PMCs derived using MLS T and H2O and SBUV show upward trend
[Shettle et al., 2009]
SBUV Long-term changes
25 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Brightest clouds, mice>60 ng/m3
Both 0-D model bright PMCs derived using MLS T and H2O and SBUV show upward trend
[Shettle et al., 2009]
SBUV Long-term changes
0-D model bright PMCs derived using SABER T, and MLS H2O climatology show no upward trend.
26 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
PMC long-term change analysis summary Because Psat is near zero during the PMC season and PH2O is large, H2O is the main parameter governing LT change. WACCM ΔH2O and ΔT support this idea.
Low latitude Psat gradient is sharp and PMCs form at this edge
0-D model coupled with SABER T and MLS T and H2O, show that PMCs are occurring more often at low latitudes
Downward T trend at low latitudes drives the PMC increases
H2O and not T causes brightest PMCs to increase with time for >70N
At >55N, same number of all clouds form each year, so there is no trend
Both SBUV PMC changes and 0-D model derived changes using MLS, agree, providing some amount of validation of these results.
27 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Backup
28 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
0-D water/ice model (Hervig et al., 2009)
PH2O=H2O vmr× P (hPa)
(hPa)
(ng/m3)
Assumes that ice exists in thermodynamic equilibrium with the local temperature and water vapor, i.e. “H2O vapor in excess of saturation gets assigned to the ice phase”.
Ignores: nucleation, sedimentation, horizontal transport, time depend- ence of growth and sublimation, and the Kelvin effect.
29 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Qualitatively same as max H2O case; therefore cloud numbers are not very sensitive to H2O and trend in the low latitudes driven mostly by temperature
Lower lats Higher lats Higher lats
SABER 84 km cloud number trend for mean H2O
30 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
AIM CIPS NH June 21, 2007
31 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
SOFIE: Solar Occultation for Ice Experiment
Operates over 0.3µm to 5.3 µm range
T, NLCs, CO2, H2O, CH4, NO, O3, aerosols, cosmic smoke
2 km vertical resolution
A 16-band differential absorption radiometer (UV to IR) to simultaneously measure cloud properties and the PMC environment
32 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
High SOFIE sensitivity allows subvisible ice to be measured up to about 90km
SOFIE: Solar Occultation for Ice Experiment
33 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
CIPS: Cloud Imaging and Particle Size Experiment
λ = 0.265 µm; 1 X 2.5 km pixel size
Cloud morphology and particle sizes
CIPS: Cloud Imaging and Particle Size Experiment
Four CCD cameras image PMCs at ~ 83 km
34 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
CIPS: Cloud Imaging and Particle Size Experiment
June 18, 2009
June 22, 2009
June 26, 2009
CIPS 2009 northern summer orbit strips
Four CCD cameras image PMCs at ~ 83 km
35 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
AIM CIPS NH June 22, 2007
36 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Polar-region mice is completely controlled by H2O
SABER Mean H2O
37 May 3 – 4, 2012 Russell - 2nd CAWSES WkShp
GATS
Polar-region mice is completely controlled by H2O
SABER Max H2O