MWISP ELOG RECAPS FOR X-BAND RADAR
1523 Sunday 4-April-1999
1523 utc. We ran mostly unattended dual-wave both radars
experiment fixed on MWO yesterday afternoon and over night. Clouds
changed from shallow warm liquid in afternoon local time to heavy
rain by 9 pm local time with cold fropa, rain quit and cloud
gradually thinning but showing substantial slowly decreasing liquid
on radiometer. Geoff Hill launched a LW balloon about an hour ago.
Winds are cross valley northto south strong aloft (80 mph summit)
Goeff Koenig says it is clear on the west side to the mt--so all
this LW is orographic. we are recording cross valley winds briefly
now in Xband VAD. Rain gauge was operating, so it should tell us
when SMR (scanning microwave radiomtere) data are saturated, when
good. Ending todays X-band ops shortly. will run unattended K
band rhimrrmwo this afternoon.
*+*+ Name of the current author : reinking
2129 Tuesday 6-April-1999
Did NOAA/D clutter map. PPI vol 0-about 26 deg el in 2 deg steps.
Then approx .equivalent of rhidwE scan (rhis on MWO)., did el 0 to
35 deg. 87.2-88.0 deg.
*+*+ Name of the current author : Reinking
1123 Thursday 8-April-1999
See K-band elog for this time. Ran unattended overnite. Both radars
OK this a.m.
1535 Thursday 8-April-1999
Dual-wave unattended over nite, attended a.m. our 2 radars , some
of UMASS radar, and our radiometer all fixed on MWO, except our SMR
went to scanning late to test its reliability. Started with
dissipating clouds, then clearing, then altostratus early a.m.
local time, then rain and snow showers alternating, now lifting and
only a broken weak stratus layer below mtn top--weakly visible on
this radar between 3 and 4 km range. K shows about -27 dBZ cloud
between 2 and 6 km range approx.(maybe not on K either).
1931 Thursday 8-April-1999
A long period with variable weather. There are certainly
interesting monents at the summit. The next 36 hours are
expected to be boring.
2305 Saturday 10-April-1999
Long, cold day with our first concerted attempt at maintining
coordinated scanning amoung all groups on a repetitive routine
basis. Weather went from partly cloudy in the morning to
thickening cloud by midmoring and light snowfall all afternoon as
temperatures dropped from about +1 to -3C at the CRB. We mostly
did alternating hours of scanning for the polarization work and
fixed beam over the mountain for dual- and triple-wave work. The
radiometer was not able to continue scanning very long at all. It
spent most of the day doing fixed beam over the MWO or vertical.
The radars also had a number of data system freeze ups - mostly the
K-band. There was some measureable liquid present at times, as
well as long periods with large aggregate snowflkes falling at the
CRB. Might be useful data for both the multi-wave and the
polarization research. The nice thing is that we watched nearly
the full evolution of the system which was wrap-around cloudiness
from the northwest. X-band used tapes 019 and 020 today.
2027 Monday 12-April-1999
Fair weather cumuli on a cold day. No data were collected with the
X-band.
1908 Tuesday 13-April-1999
Another case of northwest flow with shallow cloud. A solid
overcast lasted several hours and produced very light snow at the
CRB. Radars operated mainly in the routine mode, alternating each
hour between scanning and fixed beam. The cloud top was near 8 kft
MSL all day but was somewhat higher over the peaks SE of the CRB.
The Twin Otter attempted to get into cloud, but the FAA restriction
of maintaining at least 8 kft in the area prevented them from doing
much. They did make several passes at 8 kft and managed to
penetrate small parts of the cloud which stuck up above that level,
mainly north of the CRB. At times the MWO reported LWC up to 0.5
g/m3 with the decent upslope forcing. The radar data may be useful
for both the polarization and multi-wave research, but usefulness
is limited once again by the fact that these were not deep clouds.
2131 Wednesday 14-April-1999
Another day of cold NW flow with overcast. A low cloud layer with
top near 8-10 kft MSL persisted all day. A midlevel cloud also was
present at times and was quite variable in thickness and character.
Late in the afternoon prominent lee waves were observed with both
radars, especially Ka-band. In the late afternoon the layers
merged for a while, giving us the deepest cloud so far this month.
There were periods of very light snow. Also periods when there
apparently was a fair amount of liquid water. Radars spent the
entire day alternating hours of fixed beam and scanning. The
aircraft stood by but did not fly. Radiometer did fixed beam over
Mt. Wash, vertical, and manual RHIs between. Might be a useful
data set for both polarization and multi-wave work.
1806 Thursday 15-April-1999
Another day of NW flow around the back side of a low pressure
system over Nova Scotia. Fixed beam dual-wave data over night in
overcast conditions conked out in both radars long before moring.
In the morning the overcast thickened abruptly and became deep
enough for the Twin Otter. There was a layer of altocumulus with
generating cells and fall streaks at about 8-11 kft MSL and a
lowery stratiform layer. The aircraft made several passes at a few
different altitudes while all remote sensors scanned away. During
the passes it began snowing with flakes ranging from large pristine
dendrites to lightly rimed dendrites to occasional large
aggregates. A little fixed beam multi-wave data were obtained
after the flight.
202 Saturday 17-April-1999
Deep warm frontal clouds with SW flow moved into the area in late
afternoon. Produced a few drops drirzle but depth was very
shallow. A fascinating ribbon of strong downslope flow was
detected by both Ka- and X-band just above the western slopes of
Mount Washington. Radars were set to run unattended overnight to
document this interesting airflow. X-band will do VADs
continuously, Ka-band will do RHIs continuously. Radiometer
vertical over night.
1802 Saturday 17-April-1999
Low stratus following a night of snowfall. The unattended VAD
scans with the X-band ended after 8 hours because of a data system
problem. But those data may be very good for a study of last
night's shallow downslope flow. Today, clouds once again were too
low most of the day for the aircraft to get into. There were a
couple of hours with light showers of column crystals at the CRB.
Tempertaure at the surface hovered just above freezing until the
sun broke through in the early afternoon. We alternated between
scanning and fixed beam. But most of the time the path length was
too short for dual-wave work, even toward the west, because the
clouds were shallow.
1601 Sunday 18-April-1999
A thin, low stratus was almost too weak to be detected at X-band.
Indications are that this was an iceless cloud. But because it was
so thin and weak it probably will not be useable for dual-wave
work. We ran some fixed beam and some scanning, but these are
unlikely to be useful for anything.
2000 Monday 19-April-99
No data collected today by either radar.
2124 Tuesday 20-April-1999
see kband elog for recap.
1918 Monday 26-April-1999
operated D in kinetics queue (vads, domer, vol) most recently for
NASA 607 operation. with K-band scanning. D in fixed beam for most
of day prior to that. See K-elog for when dual-wave actually done.
Best dual wave was probably about 1.5 hr thru the evolution of a
graupel/rain shower--so LW rampup, rain and graupel, and Lw
rampdown--several challenges. Path length probably bad all day
since the clouds are all convective. Early on, very low DBZ clouds
so D probably did not see them.
*+*+ Name of the current author : roger
1945 Tuesday 27-April-1999
Intermediate recap. The best thing from the X-band is a very long
period of dual wave in fixed beam to the west at 10 elev during a
period when the lw on this path was around 3.5 -3.5 mm. K
interspersed some rhis for crystal work, so compare logs for actual
times of dual wave. Late in day the a/c flew a mission when we
were experiencing mostly heavy aggregation. We operated in scanning
mode during that period, kinetics queue. A/c measured almost no LW
except at min alt (8.3 kft = just under 2 km agl) in those flights,
even tho cloud was to about 12 kft (2.5 km agl--cog site). We are
in fixed dual wave now and the radiometer scanning program is fixed
and also pointing up the mtn. flow has been cross valley and later
from NE so weak downslope flow primarily, thur cog site all day.
1213 Thursday 29-April-1999
Operated in unattended dual-wave nite before last, leading into
severe clear yesterday. Rime on trees on slopes of MWO suggested
good LW cloud overnite, or snow on trees for 27 april case. Check
the melt level altitude. Was the rime line melt level or cloud
base?
1559 Thursday 29-April-1999
Best thing for X-band was some dual-wave this a.m. during which LW
cycled thru a peak and went thru a long slow decline. We
erroneously left K in slant-linear pol, but kept it there thru the
whole dual wave operation, so the reflectivity is consistent (if it
was effectd at all). Cloud was deepest we have seen, extending
beyond 19.2 km max range, had high and very low dBZ layers.
Eventually layers thinned/separated. Ran kinetics queue for 08000845 L (1200-1245 utc) (approx) ops in flow from NE which overrode
slower downslope flow thru valley, creating a speed shear zone at
1 km agl. then started the dual-wave, then went back to kinetics
while finishing morning with a LW profiling expt with K and the SMR
in lenticulars capping Mt. Washington.
IT is clearing and THIS MAY be the last operation of MWISP.
*+*+ Name of the current author : Reinking