Eos, Vol. 88, No. 48, 27 November 2007
w a s h o n o r e d for work that t h e E x p l o r e r s Club says h a s "revolutionized t h e field of c l i m a t e c h a n g e through t h e d i s c o v e r y of a b r u p t c l i m a t e c h a n g e a n d h u m a n i m p a c t s o n t h e c h e m i s t r y of t h e a t m o s p h e r e . "
J u l i e P a l a i s , w h o d i r e c t s t h e A n t a r c t i c G l a c i o l o g y P r o g r a m in t h e U.S. National
World Data Center Conference 2007;
Bremerhaven, Germany, 7-9 May 2007
PAGE 5 2 4
A l m o s t 5 0 y e a r s a g o , t h e World Data Cen
ter ( W D C ) s y s t e m w a s founded through t h e International C o u n c i l for Scientific Unions ( I C S U ) in o r d e r to a r c h i v e a n d distribute data c o l l e c t e d from t h e o b s e r v a t i o n a l pro
g r a m s of t h e 1 9 5 7 - 1 9 5 8 International G e o p h y s i c a l Year. Originally e s t a b l i s h e d in t h e United S t a t e s , E u r o p e , Russia, a n d J a p a n , t h e WDC s y s t e m h a s s i n c e e x p a n d e d to 51
S c i e n c e Foundation's Office of P o l a r Pro
g r a m s , w a s h o n o r e d for r e s e a r c h into t h e u s e of v o l c a n i c ash in i c e c o r e s to study t h e p a l e o c l i m a t e r e c o r d of t h e G r e e n l a n d a n d A n t a r c t i c i c e s h e e t s . S u s a n S o l o m o n , a s e n i o r s c i e n t i s t at NOAA's Earth System R e s e a r c h L a b o r a t o r y in Boulder, Colo., is
c e n t e r s in 12 c o u n t r i e s . Its current h o l d i n g s a r e t r a n s d i s c i p l i n a r y a n d i n c l u d e a w i d e r a n g e of solar, g e o p h y s i c a l , e n v i r o n m e n t a l , a n d h u m a n d i m e n s i o n s data c o v e r i n g t i m e - s c a l e s ranging from s e c o n d s to m i l l e n n i a . T h e s e data provide t h e b a s e l i n e informa
tion for r e s e a r c h in m a n y ICSU d i s c i p l i n e s , but e s p e c i a l l y for monitoring c h a n g e s in t h e g e o s p h e r e a n d b i o s p h e r e .
In o r d e r to revise a 50-year-old s t r u c t u r e a n d to d e v e l o p appropriate short- a n d
k n o w n for h e r c l i m a t e a n d o z o n e work, including r e s e a r c h that led to d i s c o v e r i n g t h e c a u s e of t h e A n t a r c t i c o z o n e h o l e . S o l o m o n a l s o c o c h a i r s Working Group I of t h e Intergovernmental P a n e l o n Climate C h a n g e .
thus b e c o m e s w i d e r a n d denser, a n d it h a s n o s h a r p outer boundary. Further, t h e Clus- ter/CODIF ( C o m p o s i t i o n a n d Distribution F u n c t i o n Analyzer) ion s p e c t r o m e t e r , in its c o l d p l a s m a d e t e c t i o n m o d e , h a s poten
tially r e v e a l e d t h e e x i s t e n c e of a n outward p l a s m a s p h e r i c wind in this situation. W h e n a strong s o l a r wind d i s t u r b a n c e s e t s in, t h e e l e c t r i c field intensifies a n d e r o d e s t h e outer r e g i o n s of t h e p l a s m a s p h e r e . T h i s pro
d u c e s a s h a r p outer density gradient (the p l a s m a p a u s e ) . T h e e r o d e d material forms a plume, initially in t h e a f t e r n o o n s e c t o r , s o m e t i m e s e x t e n d i n g up to t h e dayside m a g n e t o p a u s e . T h e nightside e d g e of t h e p l u m e foot point s e e m s to c o i n c i d e with the i n t e n s e e l e c t r i c fields a s s o c i a t e d with i o n o s p h e r i c s u b a u r o r a l ion drifts. As t i m e g o e s by, t h e plume rotates a r o u n d Earth, often at a s p e e d slower than t h e E a r t h ' s rotation.
P l u m e s c a n e x t e n d over a w i d e l o c a l time s e c t o r ; while IMAGE EUV s h o w s their high- density part (down to a b o u t 4 0 p a r t i c l e s p e r c u b i c c e n t i m e t e r ) , Cluster s o m e t i m e s s a m p l e s t h e prolongation of t h e s e p l u m e s to e a r l i e r l o c a l times, at even lower densities.
C o n f e r e n c e s e s s i o n s reviewed h o w numeri
c a l simulations support t h e p r o p o s e d t h e o ries.
Additionally, IMAGE and Cluster c o n t r i b ute to e m p i r i c a l m o d e l s of t h e p l a s m a den
sity in t h e i n n e r m a g n e t o s p h e r e , a n d of t h e e l e c t r i c field that drives t h e c o n v e c t i o n . M o d e l s of t h e b r o a d variety of p l a s m a wave e m i s s i o n s reported by b o t h m i s s i o n s will b e useful for understanding t h e t i m e evolution of t h e radiation belts.
—JOHAN D E KEYSER, FABIEN DARROUZET, a n d VlVIANE PlERRARD, Belgian Institute for S p a c e Aeronomy, Brussels; E-mail: J o h a n . DeKeyser
@ a e r o n o m i e . b e
medium-term strategies, a W D C c o n f e r e n c e w a s c o n v e n e d in B r e m e n , G e r m a n y . Hosted by t h e World Data Center for M a r i n e Envi
r o n m e n t a l S c i e n c e s ( W D C - M A R E ) a n d t h e Alfred W e g e n e r Institute for P o l a r a n d Marine R e s e a r c h , a n d s u p p o r t e d by t h e G e r m a n S c i e n c e Foundation ( D F G ) a n d t h e ICSU, t h e c o n f e r e n c e w a s d e d i c a t e d to four m a i n s u b j e c t s :
1. WDC and GEOSS: T h e c u r r e n t G l o b a l Earth O b s e r v a t i o n System of S y s t e m s ( G E O S S ) effort is c o n c e i v e d for s y n o p t i c a c c e s s a n d l a r g e - s c a l e a n d c o m p l e x analy
sis of all t y p e s of e m p i r i c a l data. All s u b s c r i b i n g n a t i o n s have a u n i q u e role in d e v e l o p i n g a n d maintaining t h e s y s t e m , c o l l e c t i n g data, e n h a n c i n g data distribution,
MEETINGS
A New Perspective on the Earth's Plasmasphere
The Earth's Plasmasphere: A Cluster, IMAGE, and Modelling Perspective;
Brussels, Belgium, 19-21 September 2007
PAGE 5 2 4
Sixty y e a r s a g o , O w e n Storey c o n c l u d e d that "whistler" radio w a v e s p r o p a g a t e a l o n g t h e g e o m a g n e t i c field lines through a dis
persive m e d i u m , w h i c h is now k n o w n a s t h e p l a s m a s p h e r e . T h i s w a s c o n f i r m e d by Gringauz's p l a s m a m e a s u r e m e n t s o n Lunik 2 in 1 9 6 2 . In r e c e n t y e a r s , satellites s u c h a s NASA's I m a g e r for Magnetopause-to-Aurora G l o b a l E x p l o r a t i o n (IMAGE) a n d t h e Euro
p e a n S p a c e A g e n c y ' s Cluster p r o b e s have offered w h a t previous s p a c e c r a f t c o u l d not:
a n o n l o c a l p e r s p e c t i v e .
As IMAGE a n d Cluster have a c c u m u l a t e d m o r e t h a n 6 y e a r s of o b s e r v a t i o n s , r e s e a r c h e r s from b o t h c o m m u n i t i e s j u d g e d t h e t i m e w a s ripe for a review at a work
s h o p o r g a n i z e d last S e p t e m b e r by t h e Bel
gian Institute for S p a c e A e r o n o m y (http.7/
w w w . a e r o n o m y . b e / e n / w o r k s h o p /
p l a s m a s p h e r e / o v e r v i e w . h t m ) . T h i s m e e t i n g report s u m m a r i z e s s o m e highlights of t h e m e e t i n g .
An i m p o r t a n t t o p i c d i s c u s s e d involved t h e e m e r g e n c e of n e w m e t h o d o l o g i e s for a n a l y s i s of IMAGE a n d Cluster data. IMAGE, w h i c h c e a s e d o p e r a t i o n s in 2 0 0 5 , c a r r i e d a n e x t r e m e ultraviolet ( E U V ) i m a g e r that p r o d u c e d g l o b a l p l a s m a s p h e r e pictures e v e r y 10 m i n u t e s by r e c o r d i n g r e s o n a n t l y s c a t t e r e d h e l i u m ion ( H e+) e m i s s i o n at 3 0 . 4
n a n o m e t e r s . T h e rich detail in t h e s e i m a g e s h a s inspired a n e w m o r p h o l o g i c a l n o m e n c l a t u r e (http://image.gsfc.nasa.gov/poetry/
d i s c o v e r i e s / N 4 7 b i g . j p g ) . P r e s e n t a t i o n s at t h e m e e t i n g s h o w e d h o w the EUV t e a m c a n infer t h e flow field b y c r o s s - c o r r e l a t i n g details in s u b s e q u e n t i m a g e s . IMAGE'S radio p l a s m a i m a g e r ( R P I ) wave instrument pro
v i d e s a picture of its e n v i r o n m e n t b y a c t i v e radio sounding, t h e r e b y discovering, for i n s t a n c e , w a v e d u c t s of finite e x t e n t a l o n g t h e m a g n e t i c field lines.
O t h e r s e s s i o n s r e v e a l e d h o w t h e four- s p a c e c r a f t Cluster c o n s t e l l a t i o n gives a n i d e a of larger-scale structure in t h e p l a s m a s p h e r e w h e n t h e s p a c e c r a f t s e p a r a t i o n is large. For small s e p a r a t i o n s , diverse t e c h n i q u e s allow c o m p u t i n g the m a g n e t i c field g r a d i e n t s — a n d thus the c u r r e n t s — a s well a s t h e density gradients (density inferred from t h e p l a s m a f r e q u e n c y identified by t h e WHISPER ( W a v e s of High F r e q u e n c y a n d S o u n d e r for P r o b i n g of E l e c t r o n Density b y R e l a x a t i o n ) instrument).
T h e s e n e w m e t h o d o l o g i e s have c r e a t e d a g r e a t e r u n d e r s t a n d i n g of p l a s m a s p h e r e d y n a m i c s , w h i c h evolve in a c y c l i c pattern.
P r e s e n t a t i o n s c o v e r e d how t h e p l a s m a s p h e r e is refilled from the i o n o s p h e r e in a slow bottom-up p r o c e s s w h e n t h e s o l a r wind is s t e a d y a n d t h e m a g n e t o s p h e r i c e l e c t r i c field is c o n s t a n t . T h e p l a s m a s p h e r e
