1. Scientific objectives

According to the MAP U.S. Overview Document, the purpose of Wet MAP is to investigate the mechanism of orographically generated heavy precipitation events with special emphasis on their dynamics, microphysics, and hydrological consequences (especially flooding). The specific objectives are:

A. Distinguish the relative roles of orographic, baroclinic, and convective dynamics in the airflow producing precipitation over mountains.

B. Distinguish the different effects of the barrier scale in presenting an obstacle to the flow, broad indentations in the barrier in focusing the convergence and lifting on the windward slope of the barrier, and individual river valleys in concentrating the flow and runoff to produce floods.

C. Determine the four-dimensional variability of precipitation microphysics in orographically influenced heavy precipitation and flooding events.

D. Estimate the rain and runoff quantitatively over the primary precipitation and flooding zones, the regions of Ticino, Friuli (Friuli is defined here as the northeastern prealpine area extending from Veneto to Slovenia through Friuli), and Liguria [Fig. 1].

E. Obtain measurements that will aid in the validation of the precipitation physics of high-resolution numerical weather prediction models.

2. Wet MAP Intensive Observation Periods (W-IOPs)

Radar data collection in Wet MAP will be maximized during times designated as Wet MAP Intensive Observation Periods (W-IOPs). Any day on which significant precipitation is forecast for one or more of the target regions (Ticino, Friuli, or Liguria) will be a W-IOP. During a W-IOP, all ground-based radars will be operated, and the Italian operational radars will transmit full three-dimensional volume-scan data. Whenever possible during a W-IOP, Wet MAP aircraft flights will be carried out over the ground-based radar network.

3. Wet MAP observational strategy

To accomplish the scientific objectives of Wet MAP, a nested observational strategy has been designed. The networks of operational radars and rain gauges in northern Italy provide a broad general spatial context. MAP aircraft will conduct flights over the region covered by these radars (see Wet MAP Aircraft Plan). The WP-3D and Electra aircraft will provide airborne dual-Doppler measurements and cloud physics sampling in specific subregions of the area covered by the Italian radars. The French ARAT aircraft will supplement the WP-3D and Electra measurements with low-level upstream thermodynamic, moisture, and wind data. The German Falcon aircraft will provide high-level ice-particle imagery during some aircraft missions. In the Ticino region more detailed observations will be provided by 10 ground-based research radars (Fig. 2). The French RONSARD radar and Swiss Monte Lema radar will provide a background of dual-Doppler radar data over the Ticino region. The U. S. S-Pol radar will provide a third Doppler radar in this region, to increase the resolution of dual-Doppler measurements within the French-Swiss array and to provide dual-polarization measurements to map the microphysical structure within the dual-Doppler array. Three small specialized radars will provide vertical profiles of reflectivity (the U. S. S-band OPRA, the Swiss X-band, and the German Ka-band). The U. S. Doppler on Wheels (DOW) will obtain Doppler radial velocity measurements of the winds in specific river valleys to indicate how the flow is modified on the valley scale. Whenever possible, Wet MAP aircraft missions will be flown over this highly instrumented Ticino region in coordination with the 10 ground-based research radars (Fig. 2). When precipitation is occurring in the Friuli or Liguria regions and not in the Ticino region, the aircraft flights will be conducted in the Friuli or Liguria regions, with priority on the Friuli region, and coordinated with the Italian operational radar array (Fig. 3).

4. Project Operations Center (POC)

To coordinate the aircraft and ground-based observations in Wet MAP, a Project Operations Center (POC) will be operated in northern Italy, at the Linate military air base outside Milan. The Regional Meteorological Center located on this base will host the POC. The POC will coordinate both the ground and air operations of Wet MAP.

a.Daily coordination with MOC on general MAP operations

The Center Director, POC Operations Director, and Science Coordinator will communicate regularly with the MOC on all aspects of MAP planning including aircraft, radar, and other special observing systems utilization during intensive observation periods. Details of these interactions are provided in Sections 6 and 7. Descriptions of staff responsibilities are provided in Section 3d.

b. POC coordination of ground-based operations

During all W-IOPs the POC will coordinate the data collection by Wet MAP meteorological radars. In addition to the radars in the Ticino region (Fig. 2), the Wet MAP meteorological radars include six C-band Italian operational Doppler radars (Fig. 3; Bric della Croce, Fossalon di Grado, Pisa, Teolo, Spino d'Adda, S. Pietro Capofiume, shown by red circles). Since the DOW is a roving radar, it will have to be deployed each day to a location recommended by the POC. Since the S-Pol, RONSARD, and ETH VPR radars will not be operated continuously, the POC will determine when those radars should be activated. (The Karlsruhe and OPRA radars will run continuously from early September to mid-November.) The POC further must decide the specific scan strategies to be carried out at the S-Pol and RONSARD radars. The scan strategy options are discussed below in Secs. 4b-c.

During a non W-IOP operation, the engineering staff will monitor data flow from the radars to POC. Radar scientists will monitor all participating Italian and Swiss operational scanning radar. Radar scientists will notify the POC Operations Coordinator if significant precipitation appears to be developing.

During a W-IOP, the engineering staff will monitor data flow to the POC from the S-Pol, RONSARD, Monte Lema, Bric della Croce, Fossalon di Grado, Pisa, Teolo, Spino d'Adda, San Pietro Capofiume, and Istrana radars. Radar scientists will produce hourly composite radar images on the MountainZebra system and provide them around the clock to MOC via the JOSS catalog, within ~15 min of data collection from RONSARD, Mt. Lema, and S-Pol radars, during all operational periods. On the day following a W-IOP, radar scientists will generate mission summaries and post them on the JOSS catalog.

c. POC coordination of Wet MAP aircraft operations

On W-IOP days when the MAP aircraft fly Wet MAP missions, the POC will take on additional responsibilities. Planning the flights of Wet MAP will be done each day through teleconferences between the POC and MOC Operations Directors and Science Coordinators (see descriptions below). Once Wet MAP flights are planned, they will be staged by direction from the MOC. However, when the aircraft are to obtain measurements in one of the three target areas, they will be directed in real time from the POC by the POC Aircraft Coordinator (see below). Thus, once the flights are launched, the POC becomes the critical point in the Wet MAP experiment operations.

When aircraft are flying during a W-IOP:

• Engineering staff will assure that the aircraft tracks are continually ingested into MountainZebra and overlaid on the radar composites provided every 15 min by the radar scientists.
• The Aircraft Coordinator will guide research aircraft to the general region of study and then to specific features within the radar echo pattern. The protocol for the air-ground scientific communication will be:
  • A dedicated air traffic control frequency will be used for all communications between the POC and MAP aircraft. This frequency will also be used for communications between airborne chief scientists to coordinate flight patterns or to discuss the evolving weather and flight planning strategies. A secondary communications frequency will be established as a backup, and will probably be one of the Aircraft Operation Center's company frequencies (e.g., 122.925 MHz).
  • All scientific information will be passed from the POC aircraft coordinator to the individual aircraft chief scientists over the dedicated air traffic control frequency. The use of this frequency by other personnel should be minimized.
  • The passing of information (e.g., suggested flight track information) from the POC ground coordinator to the aircraft chief scientists must be in latitude and longitude coordinates. These coordinates will be passed as degrees, minutes, and seconds. Suggested altitudes will be passed as feet above mean sea level (MSL). Coordinates such as range and radials from ground-based radars, or locations relative to towns or mountain peaks, are unacceptable!
  • Critical precipitation information to be passed from the ground coordinator to the aircraft will include: 1) locations of high reflectivity (>40 dBZ) cells, their maximum echo tops, and motion vector, 2) end point locations and orientation of reflectivity bands, as well as motion vector of bands as a whole, 3) any observer reports of severe weather such as hail, damaging surface winds, or lightning, and 4) areas of new storm growth. This information should be passed to the aircraft at least once every 15 minutes.
  • Changes in flight tracks must be given with at least 15 minutes lead time.
  • All communications with Air Traffic Control to coordinate aircraft flight tracks (and changes to flight patterns) will be done only by the pilots of each aircraft.

All final decisions regarding penetrations of precipitation features will rest with the individual aircraft pilots and are not subject to debate.

d. Coordination with regional air traffic control agencies

The POC will be responsible for alerting Italian Air Traffic Control agencies of impending MAP flight operations in Italian air space. This may include 24-hour alert notification, provision of block air space requests and/or flight tracks and mission timing. During flight operations POC personnel may be located at nearby Air Traffic Control facilities or have direct interface with Air Traffic Control personnel coordinating regional aircraft operations. The exact procedures for this coordination are still under consideration with Air Traffic Control, CMR, and project personnel.

e. Location for Italian forecasting support to MAP

The Italian CMR will be contributing forecast staff to MAP to assist with forecasting and nowcast requirements especially in the Italian region of MAP and for Wet-MAP operations in particular. This is detailed further in Section 6.

f. Operational support capabilities at the POC

The POC will be provided with a local area network to support MAP scientists housed at the POC and several important operational tools. The operations staff will utilize the MountainZebra system and scientists to coordinate aircraft flight operations and the determination of ground-based radar scan strategies to best sample weather systems of interest. The JOSS MAP on-line field data catalog will provide operations information, weather products, facility status, flight mission summaries, and preliminary field data as input from both the POC and MOC.

g. Data flow in and out of POC

The coordination of Wet MAP ground and air operations by the POC requires the real-time data flow in and out of the POC shown in Fig. 4. Three-dimensional volume-scan data from 10 radars (S-Pol, RONSARD, Monte Lema, Bric della Croce, Fossalon di Grado, Pisa, Teolo, Spino d'Adda, San Pietro Capofiume, and Istrana) will be transmitted to the POC in real time. At the POC, the data from these 10 radars will be processed to the point that they are mapped to a navigated Cartesian grid and converted to netcdf format. The netcdf files will be ingested into MountainZebra, where they will be displayed on common maps and cross sections, in a form that will facilitate the coordination of Wet MAP aircraft by the POC Aircraft Coordinator. Aircraft position data will be received from air traffic control and ingested into MountainZebra so that the aircraft tracks of the Wet MAP aircraft can be plotted on the radar echo maps displayed in MountainZebra. The combined aircraft-track/radar-echo maps in MountainZebra will be the POC Aircraft Coordinator's primary visual aid in guiding the Wet MAP aircraft in real time. The communications network at the POC are indicated in Fig. 5. The MAP LAN portion of that figure (light blue line) that indicates the specific hardware required to accomplish the MAP data processing is further resolved in Fig. 6.

The coordination of Wet MAP ground and air operations by the POC requires this real-time data flow (Fig. 4). Three-dimensional volume-scan data from 10 radars (S-Pol, RONSARD, Monte Lema, Bric della Croce, Fossalon di Grado, Pisa, Teolo, Spino d'Adda, San Pietro Capofiume, and Istrana) must be transmitted to the POC in real time. At the POC, the data from the 10 radars will be processed to the point that they are mapped to a navigated Cartesian grid and converted to netcdf format. The netcdf files will be ingested into MountainZebra, where they will be displayed on common maps and cross sections, in a form that will facilitate the coordination of Wet MAP aircraft by the POC Aircraft Coordinator. Aircraft position data will be received from air traffic control and ingested into MountainZebra so that the aircraft tracks of the Wet MAP aircraft can be plotted on the radar echo maps displayed in MountainZebra. The combined aircraft-track/radar-echo maps in MountainZebra will be the POC Aircraft Coordinator's primary visual aid in guiding the Wet MAP aircraft in real time.

h. POC staff responsibilities

The POC will be staffed by the following essential personnel, whose responsibilities are as follows:

• POC Center Director:G. Frustaci. Responsible for overall activities of POC. Will facilitate communication and cooperation of MOC and POC forecasting and science teams. Will be responsible for day-to-day logistics and staffing of Italian forecasting and air traffic control personnel at POC.
• POC Operations Director: Jim Moore or alternate. Responsible for:
  • coordination of scientific activities of MOC and POC
  • coordinating daily deployment and operation of ground-based research radars
  • deployment of ancillary instruments (esp. soundings and rain gauges)
  • day-to-day tracking status of all Wet MAP facilities
  • day-to-day logistics and staffing of scientific personnel at POC.

  

  Alternates: R. Houze, R. Rotunno, M. Steiner, D. Dirks, J. Wilson, F. Roux

• POC Science Coordinator: R. Houze or alternate. Responsible for ensuring that scientific objectives of Wet MAP are being filled, conducting quick-look analysis, leading daily meeting, and participating in daily conference call with MOC. Alternates: R. Rotunno, M. Steiner, J. Wilson, F. Roux, E. Richard.
• POC Aircraft Coordinator: R. Houze, J. Moore, or alternate. Communicates with airborne mission scientists during flights to coordinate and optimize the flight tracks of the NCAR Electra, NOAA P-3, DLR Falcon, and the French ARAT aircraft with respect to Wet MAP science objectives. This direction and coordination will be based on real-time radar and satellite data available at the POC. The objectives will be to place the aircraft in one of three primary orographic precipitation regions: Ticino, Friuli, or Liguria. Ticino will have the highest priority since it is the location of the ground-based radars. Once the aircraft are committed to one of these regions, the aircraft coordinator (working closely with the local liaison to the air traffic control system) will advise the aircraft mission scientists on tracks that will best optimize the aircraft radar and microphysical measurements in relation to ground-based radar observations. This direction and coordination will be based on real-time radar and satellite data available at the POC. Alternates: A. Buzzi, R. Rotunno, M. Steiner, J. Wilson, R. Dirks, F. Roux.
• Engineering Staff: Stacy Brodzik, Chris Burghart. Maintain computer hardware and communications hardware and software, in collaboration with Italian Air Force personnel. Administer local computer network in POC and its connections to external network. Manage data flow into POC from 10 radars (S-Pol, RONSARD, Monte Lema, Bric della Croce, Fossalon di Grado, Pisa, Spino d'Adda, San Pietro Capofiume, Istrana, and Teolo). The received data, whether polar or Cartesian, should be converted to Cartesian netcdf files appropriate for ingesting into MountainZebra. These data must be displayed on MountainZebra. They must be near real time and updated every 20 min. The displayed fields should be 3-D and should allow for the data from the seven radars to be portrayed on the screen as a composite horizontal echo pattern and for arbitrary vertical cross sections of the data to be displayed on demand. The raw data received and the netcdf files will be archived. The continually updated Mountain Zebra display will include current aircraft position and tracks for the last hour. These tracks will be provided to the engineering staff from Italian civilian and military air traffic control by a method which is still being determined. As a backup, the aircraft position will be provided at intervals of ~5 min by voice communication from each aircraft to the POC.
• Radar scientists: C. James, Z. Zeng, S. Medina, G. Jaubert, plus one person from Laboratoire d'Aerologie, K. Pearl (part-time), and R. Meitin (part-time). Monitor radars during both non-operational and operational periods. Advise POC operations director of any significant changes in radar echo pattern. During periods of precipitation over any of the three focus regions (Ticino, Friuli, and Liguria), produce hourly radar images and provide them around the clock to MOC, within ~15 min of data collection from RONSARD, Mt. Lema, and S-Pol radars, during all operational periods. Provide post-mortem summary charts of each aircraft mission on which are overlaid the aircraft tracks, aircraft radar, and ground-based radar. Provide a complete set of these summary charts to MOC within 24 hours of mission.

The POC staff members described in the preceding section will work on a daily schedule beginning at 0600 UTC and ending at 1800 UTC, unless a MAP aircraft mission is occurring and needs guidance from the POC, in which the workday will extend until the end of the flight. The responsibilities of the POC staff given in the preceding section will be accomplished on a fairly strict schedule within the workday. The schedule on a given day depends on the type of MAP event occurring on that day. Each day at the POC will be designated as one of the following types of events:

• NonIOP down day
• Dry MAP-IOP, no Wet-MAP alert
• Wet MAP alert, no IOP going on
• Wet-MAP alert, Dry MAP-IOP going on.
• W-IOP, no A/C
• W-IOP with A/C

The daily responsibilities of all the key staff members are given in tables by time of day.

5. Ground-based radar operations

The research radars in Wet MAP (Fig. 2) follow different operating procedures as shown in Table 1, which summarizes the scan strategies of the research radars and Table 2, which lists the fields recorded by all the Wet MAP research and operational radars and displayed in the POC. The operating procedures summarized in these tables are discussed in more detail below.

a. Monte Lema operations

The Monte Lema radar operations are described in Operational Use of Radar for Precipitation Measurements in Switzerland by J. Joss et al. (1998, VDF Hochschulverlag AG, an der ETH Zurich, 108 pp). The radar operations and products transmitted are fixed to serve Swiss Meteorological Agency requirements. These operations will not be altered for MAP. The Monte Lema radar obtains a volume scan consisting of ten 360 degree azimuth sweeps every 2.5 min. The set of elevation angles alternates from one scan time to the next. A scan made up of elevation angles -0.3, 1.5, 3.5, 5.5, 7.5, 9.5, 13, 18.3, 25.3, 34.5 is performed in 2.5 min and is followed by the set 0.5, 2.5, 4.5, 6.5, 8.5, 11.0, 15.5, 21.6, 29.6, 40.0, which also takes 2.5 min. Thus it takes 5 min to complete a single high-resolution volume scan, composed of these two interleaved low-resolution volume scans.

Measurements are performed with gates of 83 m where 33 rays per azimmuthal degree are averaged to compute the associated gate value. Twelve contiguous gates are processed: those identified as clutter are rejected and the remaining are averaged to build the resultant 1-km gate observation. The number of 1-km gates depends on the elevation angle in order to sample a vertical cylinder of 230-km radius for reflectivity (130 km for Doppler velocity) and 12.5-km height.

For MAP, the Monte Lema radar data will be transmitted via an internet connection to the POC, in the form of standard SMA products:

• POLARU (Doppler radial velocity, 20 elevations), POLARZ (reflectivity, 20 elevations),
• TODAY (horizontal map of peak value of reflectity in the vertical column overlying each horizontal grid element),
• RAIN (best estimate of radar-derived precipitation rate), and
• WIND (vertical profile of horizontal wind derived by VAD methodology).

During W-IOPs Monte Lema velocity data will be unfolded at the POC by means of an algorithm supplied by the University of Washington. At the POC a reflectivity volume will be interpolated to a 3 km x 3km x 1 km grid every 20 min, the simultaneously observed radial velocities will be interpolated to the same grid at the same times (every 20 min), and the radial velocity volume will be combined by dual-Doppler synthesis with a RONSARD volume at least once every 60 min.

b. RONSARD operations

The RONSARD will be operated to obtain dual Doppler data in coordination with the Monte Lema radar on a 10-min cycle continuously throughout all W-IOPs in which rain occurs in the Ticino region. The RONSARD will conduct a sequence of scans at 20 elevation angles once every 10 min. The RONSARD will obtain only "VAD" scans (i.e. a series of PPI at increasing elevation, see below) for either 180 or 360 (preferred) degrees azimuth and will be conducted according to one of the following sequences (labeled A-L):

A: 512 100-m wide range gates every 100 m (i.e. range 0.1->51.2 km), 360 degrees azimuth. (Note however that the first 3 gates are for technological purposes only.)

B: As A, except for azimuths between 21.5 and 201.5 deg from North (clockwise).

C. As A, except for azimuths between 201.5 and 21.5 deg from North (clockwise).

D: 512 100-m wide range gates every 200 m (i.e. range 0.2 ->102.4 km), 360 degrees azimuth.

E: As D, except for azimuths between 21.5 and 201.5 deg from North (clockwise).

F. As D, except for azimuths between 201.5 and 21.5 deg from North (clockwise).

G: 512 200-m wide range gates every 200 m (i.e. range 0.2 ->102.4 km), 360 degrees azimuth.

H: As G, except for azimuths between 21.5 and 201.5 deg from North (clockwise).

I. As G, except for azimuths between 201.5 and 21.5 deg from North (clockwise).

J: 512 200-m wide range gates every 400 m (i.e. range 0.4 -> 204.8 km), 360 degrees azimuth.

K: As J, except for azimuths between 21.5 and 201.5 deg from North (clockwise).

L. As J, except for azimuths between 201.5 and 21.5 deg from North (clockwise).

Sequences D, E, and F will be preferred to G, H, and I. For sequences A-I, there will be 20 elevations at: 0.62, 1.23, 1.85, 2.46, 3.08, 3.69, 4.31, 4.92, 5.54, 6.15, 6.77, 7.38, 8.35, 9.67, 11.43, 13.89, 17.75, 24.35, 37.71 and 69.43 degrees from horizontal. For sequences J,K, and L (200-km range), we will probably use only the 4 first (0.62, 1.23, 1.85, 2.46) elevations. The highest priority will be on the 360-deg azimuth, 100-km range scans (i.e., sequence D). Sequence G gives less precise measurements; it is only for insurance, as it gives the best coordination with S-Pol and Monte Lema. Changes will be made according to the presence of precipitation in a limited part of the scanning domain [shorter range (50 km)- Sequence A, narrower azimuthal range- Sequence B, C, E, F], or to the position of the P3 and/or Electra. Any decision to change the azimuth or range will be based on consultation with the POC and will be coordinated with S-Pol (if necessary). It may turn out that it is better to continue the 360-deg and 100-km scans (Seq. D) whatever happens within the scanning region, so as to have a homogeneous data set (as Monte Lema will). These are open questions that will be considered in the field and in consulation with the POC. The 200-km range scans (360-deg J and 180-deg K and L) have only four elevations and will be used only qualitatively.

The RONSARD's typical scanning rate is 15 deg/sec. It takes about 3 sec to change elevation (and direction of the azimuth speed from clockwise to counterclockwise and vice-versa). So a 20-elevation sequence takes about: 20x(360/15+3)=540 sec = 9 min. A 20-elevation sequence over a 180 degree sector would take about half this time. Since Monte-Lema obtains a full-resolution, three-dimensional scan every 5 min, the proposed schedule will thus allow dual-Doppler data to be produced every 10 min if the RONSARD scans 360 degrees and every 5 min if RONSARD scans 180 degrees.

Figure 7 summarizes the data flow from the RONSARD and Monte Lema radars. The RONSARD data will be transmitted to the POC via an ISDN line. 20 min. (This frequency is subject to testing by French scientists and engineers in spring 1999.) At the POC the three-dimensional fields of reflectivity and radial velocity in this volume will be interpolated to a 3 km x 3 km x 1 km grid and ingested into MountainZebra. The velocity data from RONSARD will be combined at the POC with the corresponding Monte Lema and/or S-Pol data into a multiple-Doppler wind field at least every 60 min. This will be done on a PC-LINUX machine using programs (dealiasing, VAD, multi-VAD analyses, horizontal wind field, variational integration of the continuity equation over complex terrain) from Laboratoire d'Aerologie (F. Roux and J. F. Georgis) and CNRM (M. Chong). Displays of the resulting 3-D wind fields (to be written as netcdf files) will be done in MountainZebra.

c. S-Pol operations

The S-Pol radar has two objectives during its period of operation from 7 Sept to 8 Nov 1999, which are illustrated in Fig. 2. The primary objective of S-Pol is to provide microphysical coverage within the broad dual-Doppler coverage of RONSARD and Monte Lema (yellow lobes in Fig. 2) by performing precipitation particle-type mapping by dual-polarization measurements within a 75-km radius region centered between RONSARD and Monte Lema (red circle in Fig. 2). The secondary objective of S-Pol is to provide higher resolution dual- Doppler velocity data in the central portion of the coarser resolution RONSARD/Monte Lema dual-Doppler area. These two objectives will be accomplished by the following scan sequences which will be conducted throughout the duration of any W-IOP in which precipitation occurs in the Ticino region.

The following basic considerations will guide the S-Pol scanning:

1. Since microphysical particle typing is a primary goal of S-Pol, it will always scan in dual-polarization mode.
2. Since orographic lifting is of primary interest, S-Pol will preferentially but not exclusively collect polarimetric data in the western dual-Doppler lobes.
3. A secondary objective of S-Pol is to provide high resolution multiple-Doppler data with RONSARD and/or Monte Lema.
4. To be temporally commensurate with the 5 min (interleaved) volume scans at Monte Lema and the 5 or 10 min volume scans of RONSARD, S-Pol will operate on a 10-min cycle with 5 min dedicated to RHIs and 5 min to PPIs.
5. The maximum data collection rate of S-Pol is PRF = 1000, 100 samples (50H and 50V), all variables, and 1000 gates.

Four basic scan sequences will be used:

1. When little interesting activity is in the western lobe, full 360 degree scans, each taking 10 min, will be obtained for surveillance. Scan rate = 8 deg/sec, beam spacing in horizontal = 0.8 deg, and 12 scans elev. angles = 0.6, 1.4, 2.2, 3.0, 3.8, 4.6, 5.4, 6.2, 7.0, 7.8, 8.6, 9.4.
2. Interesting activity in the western lobe and echo tops < 8 km. Scan to at least 8 km between 30 and 100 km of radar. Sixteen 120 deg PPI sectors over western lobe plus about 50 RHIs spaced ~2.5 deg apart over the same sector. Scan rate = 8 deg/sec and PPI horizontal beam spacing = 0.8 deg. RHI vertical beam spacing = ~0.5 deg. Elevation angles = 0.6, 1.4, 2.2, 3.0, 3.8, 4.6, 5.4, 6.2, 7.1, 8.1, 9.3, 10.6, 12.1, 13.9, and 15.8.
3. Interesting activity in the western lobe and echo tops 8-10 km. Scan to at least 10 km between 30 and 100 km of radar. Seventeen 120 deg PPI sectors over western lobe plus ~50 RHIs spaced ~2.5 deg apart over the same sector. Scan rate = 9 deg/sec, PPI horizontal beam spacing = 0.9 deg. RHI vertical spacing = ~0.5 deg. Elevation angles are 0.6, 1.5, 2.4, 3.2, 4.1, 5.0, 5.8, 6.7, 7.6, 8.5, 9.6, 10.8, 12.1, 13.6, 15.3, 17.1, and 19.3.
4. Interesting activity in the western lobe and echo tops 10-12 km. Scan to at least 12 km between 30 and 100 km of radar. Nineteen 120 deg PPI sectors over western lobe plus ~50 RHIs spaced ~2.5 deg apart over the same sector. Scan rate = 10 deg/sec, PPI horizontal beam spacing = 1.0 deg. RHI vertical spacing is ~0.5 deg. Elevation angles = 0.6, 1.6, 2.6, 3.5, 4.5, 5.5, 6.5, 7.5, 8.4, 9.4, 10.5, 11.7, 13.0, 14.5, 16.2, 18.1, 20.1, 22.4, and 24.0.

The S-Pol data will be sent to the POC in real time via an ISDN line. At the POC the transmitted PPI volume scans of reflectivity and radial velocity will be interpolated to a 3 km x 3 km x 1 km grid and ingested into MountainZebra. Two particle-type algorithms (NCAR and University of Washington) will be run on RHI volumes at the S-Pol site and the outputs will be sent as sweepfiles to the POC, where they will be displayed in MountainZebra (Fig. 6).

d. Italian operational radars

Reflectivity fields observed by the six C-band Italian operational Doppler radars (Bric della Croce, Fossalon di Grado, Pisa, Teolo, Spino d'Adda, S. Pietro Capofiume, see Fig. 3) and the Istrana radar will be transmitted to the POC every 30 min according to the data flow shown in Fig. 6. During non-W-IOP times, gif imagesor BUFR files of low-level reflectivity from all seven Italian radars will be sent to the POC. During W-IOPs, volumetric scans of these six radars will be transmitted to the POC. The volumetric scans will be sent as Cartesian constant-level maps (CAPPIs) in BUFR format for the levels 0.5, 2.5, 4.5, and 6.5 km. At the POC these data will be converted to netcdf format and ingested into MountainZebra where they will be overlaid on the radar data fields from the Monte Lema, RONSARD, and S-Pol radars.

e. DOW operations

The key objective for the Doppler-on-Wheels (DOW), a mobile X-band Doppler-radar platform, will be to capture the detailed precipitation and airflow structure deep within the major Toce and Ticino river valleys that cannot be observed by the larger, fix-installed research radars scanning above the ridges or airborne radars passing overhead. A secondary objective is to provide radar coverage for the boundary-layer group at their site close to the Lodrino Airport in the Ticino River valley. DOW will operate from 7 Sept-15 Nov 1999.

Because of its mobility, the DOW may be deployed flexibly at a variety of predetermined sites. There are two primary sites considered in the Toce River valley (near Pieve Vergonte on the shoulder and the valley floor) and the Ticino River valley (Lodrino and Magadino airports), pending written approval from the local authorities and/or land owners. Additional secondary sites (with limited view) may be possible.

The site selection for a particular W-IOP will be done at the POC, depending on the weather situation and the status of accomplishment of DOW objectives. It is not anticipated that synoptic/mesoscale forecasts will be sufficiently accurate to identify a clear preference between the Toce and Ticino valleys in advance of heavy precipitation events. Typical synoptic evolution of archived flood events suggests that baroclinic forcing (evidenced by banded precipitation features) advances eastward with time. The Toce and Ticino river valleys are thus expected to be impacted in sequence, though details related to the local flow dynamics in these two regions might certainly differ. An effort will be made to obtain a representative set of observations from various sites throughout the duration of the entire IOP, in order to avoid a situation in which conclusions are overly site specific.

It would be feasible to move the DOW from one site to another during an W-IOP (e.g., from the Toce Valley over to the Ticino) to follow precipitation; however, limitations arise due to time spent in traffic, while moving from one location to the next, and a maximum sustainable operation of 12-15 hours for currently identified personnel. Thus, initially, operations based on one specified site per W-IOP will be the preferred mode. If it turns out that the airflow may be well captured within shorter time periods (a few hours) then multiple site W-IOPs may become an option.

Tables DOW-1 and DOW-2 highlight some of the basic characteristics and tradeoffs for the DOW. Given the short distances of observations possible within the valleys and the anticipated, possibly significant wind speeds (likely in excess of 30 m/s, with maxima of 80 m/s), the pulse repetition frequency (PRF) used will be in the range of 3,000 to 5,000 Hz. Using a pulse integration as given in Table DOW-1, which produces radial Doppler velocity estimates accurate to within 0.25 m/s, one may scan the antenna at roughly 15 degrees per second (Table DOW-2) without losing full areal coverage. Site-dependent properties (e.g., degree of second-trip or ground clutter contamination, sidelobes) may further influence these choices in ways that will not be obvious until actual deployment of the DOW in the field, necessitating careful attention to the quality of observations by well-trained field staff.

Table DOW-1: Radar operation tradeoffs while maintaining a 0.25 m/s resolution for the Doppler-velocity measurements. Shown are the pulse repetition frequency (PRF), the maximum unambiguous range and Nyquist velocity, and the number of pulses to be integrated per gate to achieve that.

PRF	Max Range	Nyquist Velocity	Pulse/Gate
2,000 Hz	75.0 km	16 m/s (57.6 km/h)	128
3,000 Hz	50.0 km	24 m/s (86.4 km/h)	192
4,000 Hz	37.5 km	32 m/s (115.2 km/h)	256
5,000 Hz	30.0 km	40 m/s (144.0 km/h)	320

Table DOW-2: Average beam spacing and time to complete one sweep for a given antenna rotation speed (deg/sec), independent of the PRF. The beamwidth of the DOW is roughly 1 degree (0.9 degree).

Rotation	Beam Spacing	Time/PPI
10 deg/sec	0.64 deg	36 sec
15 deg/sec	0.96 deg	24 sec
20 deg/sec	1.28 deg	18 sec

The basic scanning strategy is to operate the DOW in multi-elevation 360-degrees PPI volume scan mode, interspersed with vertical cross section RHI scans up, down, and across the valley. This basic scanning sequence will be repeated every 15 minutes. The volume scan consists of 22 elevation PPI sweeps, based on the following tilt sequence: 0.5, 1.5, 2.5, 4.0, 5.5, 7.0, 9.0, 11.0, 13.0, 15.5, 18.0, 21.0, 24.0, 28.0, 32.0, 37.0, 42.0, 48.0, 55.0, 63.0, 72.0, and 82.0 degrees.(For elevated sites above the valley floor, the sequence may start at 0 degrees, or at negative angles if the hardware allows for that and the tilt angle sequence is shifted accordingly.) This 360-degree PPI volume scan takes approximately 9 minutes to be completed (Table DOW-3), and will be followed by a series of at most 20 vertical cross section RHI scans (Table DOW-4): minimally up, down, and on both sides across the valley. However, the operator may choose to spread some RHIs over the angle of view and add sector scans as time permits. It is important though to comply with the 15-minute repetition of the basic module (22-elevation, 360-degrees PPI volume scan followed by several vertical cross section RHI scans).

Table DOW-3: 360-degrees volume scan modes and their execution time. Radar is operated with PRF=3,000 Hz and an antenna rotation of 15 degrees per second.

Mode	Pulse Width	250 Gates	Tilts	Time
P1	1.0 us (150 m)	37.5 km	22	9 min
P2	0.6 us (90 m)	22.5 km	22	9 min
P3	0.4 us (60 m)	15.0 km	22	9 min
P4	0.2 us (30 m)	7.5 km	22	9 min

Table DOW-4: 0-90 degrees vertical cross section RHI scan modes and their execution time. The radar is operated with PRF=3,000 Hz and a vertical antenna movement of 10 degrees per second.

Mode	Pulse Width	250 Gates	Time
R1	1.0 us (150 m)	37.5 km	10 sec
R2	0.6 us (90 m)	22.5 km	10 sec
R3	0.4 us (60 m)	15.0 km	10 sec
R4	0.2 us (30 m)	7.5 km	10 sec

The standard operation mode is either P2 or P3 for the volume scans and R2 or R3 for the vertical cross sections. For the Magadino Airport site in the Ticino Valley, the P1 and R1 modes may be applied because of the larger range to possibly be covered. On the other hand, for the observations at the Lodrino Airport (Ticino Valley), particularly those in coordination with the boundary-layer group (located roughly 5 km south of Lodrino), the operation modes P4 and R4 will be used to provide highest spatial resolution. For these clear air observations, a higher PRF of 4,000 Hz and/or a slower antenna rotation of 10 degrees per second may be needed to increase the sensitivity. These clear air boundary-layer observations are most likely to take place in the time frame of 20 September through 9 October, where Falcon overflights (with the downward-looking LIDAR) are anticipated in close coordination with other enhanced boundary-layer observations.

While DOW radar data will not be transmitted to the POC in real time, quick-look products (e.g., in the form of representative GIF image sequences of reflectivity and raw radial velocity) will ideally be made available for post-W-IOP debriefings at the POC and transmission to the MOC within 24-48 hours following each W-IOP.

Key personnel supporting the DOW operations include a Chief Scientist, Technician or Engineer, and 1-2 Student Operators. Their responsibilities are outlined as follows:

• Chief Scientist (Steiner, Smull): provides oversight in planning and execution of DOW deployments (incl. site selection and periods of operation); monitors progress toward meeting DOW-related scientific objectives and serves as a key point of contact at the POC for debrief and mission planning purposes; coordinates with Technician/Engineer/Operators to generate quick-look data sets.
• Engineer (Univ. of Oklahoma: McDonald, NCAR: Lutz, Randall): knowledgable in details of DOW operations; assists with set-up, operations, and data management; trains operator personnel; calibrates radar and performs any required repairs/maintenance to DOW electric system.
• Student Operators (from Univ. of Oklahoma): responsible for transporting and operating the DOW at predetermined sites during declared W-IOPs; assist in data management and generation of quick-look data sets.

f. OPRA S-band vertically pointing radar operations

The University of Washington Orographic Precipitation Radar (OPRA) will be located at Pieve Vergonte, Italy within a fenced enclosure of a power station (OPRA site). The OPRA scientist in the field will be R. Houze. The OPRA engineer will be K. Pearl. The radar antenna and shelter for the electronics will sit near the fence on a concrete-surfaced area. A Joss-Waldvogel distrometer will be located near the radar. Power for the radar and distrometer will be provided via two extension cords from the power station building. The radar will arrive in Pieve Vergonte on 6 September 1999. Setup will be completed on 7 September 1999 and OPRA will operate until 8 November 1999.

OPRA will run continuously and unattended for the duration of the Wet MAP period except for when it is down for maintenance. OPRA data will be monitored remotely via phone line. Brief checks on OPRA status will be made via a PC equipped with a modem at the POC. The modem connection will be used to ftp over recent hourly data files. Except for these status checks, real-time OPRA data will not be routinely accessible from the POC. OPRA recording media (CDs) will be changed approximately weekly. At least once a month, the engineer will perform a thorough system check which will include a receiver calibration using a signal generator and a noise-level measurement.

OPRA data recorded on the CDs will be reviewed and quality controlled using a PC in the POC by the OPRA engineer. Quicklook gif or jpeg images of OPRA data produced on the PC in the POC will be selected by the OPRA scientist for inclusion in mission summaries posted on JOSS (see Section 8).

g. ETH X-band vertically pointing radar operations

The ETH-VPR will be set up, together with various microphysical instruments in Macugnaga, Italy (7.965 deg E, 45.970 deg N), at the end of a tributary valley to the Toce River. The objective of this setup is to provide detailed microphysical data of solid and liquid precipitation particles at one point within the dual-Doppler lobes of the Monte Lema, S-Pol, and RONSARD radars. Macugnaga is also within the region where the S-Pol radar provides information about particle types performing dual-polarization measurements.

The ETH-VPR will operate during long-lasting precipitation events (at least 3 hours of continuous precipitation) and/or when airborne microphysical measurements are performed above the Ticino-Toce watershed or any other time that the POC recommends that the radar be in operation.

The time resolution of the measurements is 30-60 s, range resolution is 50 m, and vertical velocity resolution is 0.125-0.25 m/s. Together with the radar, a disdrometer and meteorological instruments will be operated. In cases of long-lasting precipitation, optical particle measuring instruments will be operated on a mountain 1500 m above the radar.

Hourly gif images of radar reflectivity and Doppler velocity of the ETH-VPR will be sent to the POC via Internet either after every W-IOP or every hour during an W-IOP. Raw data will be available after the SOP or upon request.

h. U. Karlsruhe K-band vertically pointing radar operations

The Karlsruhe Micro Rain Radar (KMRR) will be operated at Locarno during the MAP field phase. The instrument will provide vertical profiles of reflectivity, rain rate, and spectral number density in six steps up to the height of 1200 m above ground level. This will be done as one-minute mean values during the whole field phase. The KMRR will be accompanied by two optical disdrometers to give ground values of the measured parameters and to have the possibility to measure snow spectra on Cimetta (approx. 1100 m above Locarno Monti). Data will be transmitted to MDC and POC once a day during SOPs, otherwise once a week.

6. Wet MAP aircraft operations

a. Electra and P-3

The Electra and P-3 aircraft will stage out of Innsbruck 15 Sept-15 Nov and 20 Sept-15 Nov, respectively. They will provide Doppler-radar coverage and microphysical sampling of precipitation particles (with PMS probes). The airborne Doppler radar will provide the mesoscale airflow upstream of the mountains and over the windward slopes. The microphysical measurements will indicate how precipitation particles are growing within the mesoscale airflow and will serve as validation for the S-Pol particle identification algorithms. Whenever possible the two aircraft will fly joint, coordinated missions.

Since these two aircraft will be located in Innsbruck, close coordination between the POC and MOC will be required in the period leading up to aircraft departure. Typically, both aircraft will require a 12-15 hour alert notification of intent to fly. This would be done by 1600 LST for an intended take-off at 0600 LST the next day. This decision will result from discussions among flight mission scientists and POC science coordinator and the operations directors from the POC and MOC. There will be a pre-flight briefing held at the MOC 2-3 hours prior to scheduled aircraft departure. It will also include POC personnel via audio conference call. Following the conclusion of the flight mission, there will be a mission debriefing among flight mission scientists, MOC, and POC staff.

A detailed wet MAP flight plan for the Electra and P-3 has been developed by D. Jorgensen and B. Smull. The Electra/P-3 flight plans include scenarios for both single aircraft and dual aircraft missions. To summarize briefly, each flight mission will start out with a survey pattern. The survey will be one of two generic types. If the precipitation is generally spread over the windward slopes of the Alps with little evident frontal organization, the survey legs of both aircraft will run generally parallel to the Alpine crest and over the windward slopes. If the precipitation is part of an elongated organized weather system oriented perpendicular to the Alpine barrier, the survey legs of the two aircraft will be anchored to the moving feature and run generally perpendicular to the mountain barrier.

After the survey, more focused modules will be flown to document the detailed airflow in specific precipitation areas. Priority will given to precipitation over the ground-based radar network centered on the S-Pol radar. When the ground-based mission coordinator at the POC identifies the target feature, the aircraft will line up and fly in a quadruple Doppler module (composed of two approximately parallel tracks separated by ~30-40 km) centered on that feature. If air traffic considerations preclude the quadruple Doppler module, a nested pattern will be flown, with one aircraft providing higher radar resolution data within a broader pattern flown by the other aircraft. The nested pattern is not as air-traffic sensitive since the two aircraft do not have to be as closely synchronized.

Both the survey and more detailed modules are extremely simple geometrically and can be flown with the aircraft at relatively low altitudes. These factors should allow them to be executed in a dense air traffic pattern.

b. DLR Falcon

The DLR Falcon flights will be planned at the MOC and staged out of Munich. Ten hours of Falcon flight time are supported by the U. S. NSF for Wet MAP, for the purpose of sampling ice particles with PMS probes. The purpose is to help validate the S-Pol particle identification algorithms. These flights will consist of multi-level legs over the S-Pol radar at altitudes extending as high as possible above the 0 deg C level. Whenever possible these flight legs will be coordinated with the P3 and Electra Doppler radar sampling (see WetMAP Aircraft Plan).

c. French ARAT aircraft

This aircraft will stage out of Milano because of its short range. It will contribute to wet MAP operations by providing upstream conditions (see WetMAP Aircraft Plan).

7. POC Operations Coordination

The MAP Special Observing Period (SOP) will last from 7 September through 15 November 1999. There are 3 main groups in MAP that propose, approve, and conduct operations. The Principal Investigators are responsible for the formulation of proposals to use facilities to address the critical science objectives of MAP. The Mission Selection Team (MST) will be responsible for ensuring that all MAP science objectives are met during the field phase of the experiment. The MST is composed of 4 MAP principal investigators, the Scientific Director (SD) at the MOC, and the Operations Director (OD) at the MOC. One member of the MST will be at the POC. The Operations Directors are responsible for the operational implementation of the decisions made by the MST. The special measurements using MAP facilities will be concentrated in Intensive Observation Periods (IOP). The MST will define an IOP based on special observations made and related weather conditions. An IOP may vary in length from several hours to several days. The start of an IOP will generally be based on the investigators' scientific proposals for use of special MAP observing systems.

To coordinate MAP operations during an IOP, there must be close communication between the MOC and POC. A daily timeline of these communications is in Fig. 8. The processes indicated in the timeline are discussed in subsections a-g below.

a. The IOP planning process

Operations coordination for Wet-MAP activities will be an ongoing process throughout the field season. The present schedule calls for a daily planning meeting to occur at 1000 LST 7 days per week throughout the SOP.

b. Morning briefing

The PIs will receive an initial daily weather briefing each morning at about 0830 LST. In addition, the latest status information of MAP facilities will be provided. They will use this information and they prepare scientific proposals during the morning. There will be an initial coordinated presentation between POC and MOC using audio conference call. Further details may be provided independently by the POC forecasters to Wet MAP scientists following this call.

c. Ongoing IOP activities

If MAP is involved in IOP operations, it will be important for the POC and MOC to be briefed on the latest status and/or recent planning for flight operations of aircraft are still to be used on the current day. This should be done early in the morning and may precede the morning briefing as the timing of operations dictate. In the absence of aircraft operations, it will still be necessary to monitor the receipt of data from the 5 operational radars.

d. Preparation of Science Proposals At a designated time (following the morning briefing at about 0915 LST) the POC Science Coordinator will discuss the current situation with Wet and Dry MAP lead scientists at the MOC. Topics will include:

• weather situation
• Facilities status and availability
• Pressing scientific requirements
• Trade-off of facilities between Wet and Dry MAP objectives

All investigators that are interested in conducting data gathering activities will prepare short science mission proposals for consideration at the daily planning meeting. The proposals should contain the following information:

• Science objective(s) to be accomplished
• Responsible PIs
• Resource requirements
• Timing of facility use (aircraft launch times, sounding times, etc)
• Other special observing requirements (rapid scan satellite, etc.)

The PIs should use the opportunity of the morning weather brief and status update to gather information helpful to planning the mission.

e. Daily Planning Meeting

The Daily Planning Meeting will occur every day at 1000 LST. It will be co-chaired by the MOC Scientific Director and Operations Director and will take place in audio conference between the POC and MOC. The agenda will include the following items:

• Status of aircraft and ground systems (Operations Director and Status Coordinator)
• Weather discussion for 24-96 hour period (POC and MOC forecasters)
• Report on the status of MAP science objectives and recent results (Scientific Director and PIs), including previous days results, if appropriate.
• Presentation and discussion of PI mission proposals for the next 24-48 hours
• Logistics and administrative matters, other announcements

f. MST Meeting

The MST will meet immediately following the daily planning meeting (typically around 200 LST) to determine mission priorities, fix IOP start and stop times as necessary, and address items listed below:

• Selection of primary and alternate missions, including objectives and strategy and criteria for proceeding to the alternate mission IOP support staffing for the next 24-48 hours
• Schedule of facility operations: aircraft pre-flight brief times and take-off times, flight plans, other required special observations and timing, next operations update time

g. Evening updates

Members of the MOC or POC scientific, operations, or MST staff may request an evening update to assist with flight planning and priority mission decision making.

8. POC Documentation

• Facility status for all ground-based radar systems. This should be received daily, in the early morning prior to the 0830 LST morning briefing and immediately if an IOP is underway.
• Mission summaries. The Science Director will prepare an IOP summary discussion from the POC perspective. This may be done daily or at the conclusion of the IOP, whichever makes the most sense. Radar scientists must contribute to this discussion or provide separate summaries to help all MAP participants understand the evolution of precipitation systems in the region.

Summaries of the dual-Doppler radar data from the Electra aircraft will be posted on the JOSS catalog as follows: An mpeg movie of ELDORA scans at approximately 1-minute intervals will be made for every flight by the Electra scientists at the MOC. This movie will be posted on the JOSS catalog. The movie will also be archived by NCAR and the MDC. The movie consists of images, not raw data. It will serve as "metadata" for the archive of numerical data and thus allow for extremely easy selection of data of interest for research.

Summaries of the dual-Doppler radar data from the WP-3D aircraft will be posted on the JOSS catalog as follows:

• Radar composites of the P-3 lower fuselage C-band radar sweeps will be constructed for each straight and level flight leg segment. These composites will be available as gif images on the P-3 wet MAP web site approximately 2 days following the completion of each flight mission.
• Chief Scientist flight event logs, descriptive summaries, and Radar and Cloud Physics Operator logs will be posted to the wet MAP web page as text files within several hours of the P-3 return to Innsbruck from each flight mission.
• Plots of P-3 flight tracks, relative to ground topography, IR satellite imagery, and country borders will be produced and placed as gif images on the wet MAP web page approximately 2 days following the completion of each P-3 flight mission.
• Selected vertical sweep images of tail Doppler velocities and reflectivity will be created for times and locations of interest as gif images and placed on the wet MAP web page approximately 2 days following the completion of each P-3 flight mission. Selected psuedo-dual-Doppler analyses will also be created for interesting cases as time permits.
• ASCII files of P-3 aircraft data (including time, aircraft GPS position, radar altitude, temperature, dewpoint, etc) will be created at 1 sec resolution and placed on the NSSL anonymous FTP site for scientists interested in downloading the P-3 track information. These files should be available within several hours of the P-3 landing at Innsbruck following each flight mission.

All documentation discussed above will be made available to all MAP participants at the POC and MOC via the JOSS catalog. Input to the catalog may be made via FTP, email, or by using available html forms. Pictures in common formats (GIF, JPEG, PS, etc.) will be accessible via the catalog at all sites.