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meeting review

The NCAR Research Aviation Facility Fleet Workshop 18-19 February 1982, Boulder, Colo.

Peter H. Hildebrand and John McCarthy

Atmospheric Technology Division, National Center for Atmospheric Research,1 P.O. Box 3000, Boulder, Colo. 80307

Abstract

A workshop was held at the National Center for Atmospheric Re-search (NCAR) during February of 1982 to consider the scientific needs for research aircraft in the next decade and the impacts of these needs upon the fleet of aircraft that the Research Aviation Facility (RAF) supports for the atmospheric sciences research community. The workshop was attended by a group of atmospheric scientists who represented the major research interests supported by RAF. The attendees discussed scientific priorities for research in the next 10 years, the types of new instrumentation expected within the next dec-ade, and the operational requirements and aircraft fleet that would be required to serve these scientific goals.

1. Introduction

The use of ins t rumented aircraf t for a tmospher ic sciences re-search has increased greatly dur ing the last three to fou r dec-ades. Early research use of aircraf t involved simple applica-t ions of sensors mounted on civilian and military aircraf t . Modern research aircraf t , in response to new a tmospher ic re-search needs, are equipped with a wide variety of meteoro-logical sensors aimed at measuring mean and turbulent fluc-tuat ions of state variables, air mot ions , aerosols, and hydrometeors , as well as infrared and short -wave radiat ion. Because of the high cost of the p la t forms and measurement systems, many institutions turn to nat ional centers with joint-use facilities, such as the Nat iona l Center for Atmospher ic Research ( N C A R ) Research Aviation Facility ( R A F ) and the Nat ional Oceanic and Atmospher ic Adminis t ra t ion ( N O A A ) Research Flight Facility, for suppor t of their a tmospher ic sciences measurement needs.

As a tmospher ic scientists raise new quest ions, they of ten need to p robe the a tmosphere in new ways. F o r example, s t ra tospher ic measurements now appear to be an impor tan t aspect of unders tanding a tmospher ic chemistry; flight into heavy icing condi t ions is clearly an impor tan t aspect of cloud physics opera t ions ; and flight into the upper reaches of hur-ricanes and winter cyclonic s torms is essential for improved unders tand ing of these s torms and incorpora t ion of this un-

*NCAR is sponsored by the National Science Foundation.

© 1983 American Meteorological Society

Bulletin American Meteorological Society

ders tanding into numerical weather prediction models. To help researchers address these problems, new a i rborne

ins t ruments and systems are required. These systems fre-quently have negative impacts on p la t form performance . For example, compu te r technology has improved data recording and display capabilit ies, but has had a detr imental effect on the flight capabil i t ies of most a i rcraf t . In the same way, iner-tial navigat ion systems, hydrometer and aerosol measuring systems, and other ins t ruments have fur ther reduced the per-fo rmance of research aircraf t , a l though they have improved the quality and quant i ty of the measurements . For example, these improvements in ins t rumenta t ion have reduced the flight capabili t ies of the N C A R Queen Airs f rom five- to seven-hour fl ights 10 to 15 years ago to two- to f ive-hour flights in recent years. The pressures of new scientific re-search interests and new aircraft ins t rumenta t ion therefore dictate periodic reevaluation of the aircraft that are used to suppor t a tmospher ic sciences research.

The R A F Fleet Workshop was called to address the scien-tific needs for research a i rcraf t dur ing the next 10 to 15 years and to make recommenda t ions for the fu ture makeup of the Nat ional Science Founda t ion ' s (NSF) fleet of aircraft oper-ated by N C A R in suppor t of the a tmospher ic sciences. In ad-dit ion to the scientific needs for research a i rcraf t , the work-shop addressed the ins t rumentat ional developments and the opera t iona l a i rcraf t requi rements necessary to meet these scientific needs. Finally, the workshop investigated priorities for the fu tu re replacement of a ircraf t within the R A F fleet.

Section 3 of this report provides a brief interpretive sum-mary of the workshop . The next section of this report re-counts the activities of the workshop , essentially as they hap-pened. The summaries of scientific needs, ins t rumenta t ion needs, opera t iona l priorities, types of a i rcraf t , and recom-menda t ions abou t the R A F fleet are presented in the fo rm of tables fo rmula ted dur ing the workshop discussions.

2. Workshop proceedings

a. Opening remarks

The workshop was opened with welcoming and in t roductory s ta tements by Wilmot Hess, director of N C A R . He discussed the varied needs for a tmospher ic research aircraf t and the in-

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creasing flight demands on R A F . Rober t Seraf in, director of the Atmospher ic Technology Division of N C A R , followed with a discussion of the six-year lead t ime that was necessary before R A F could acquire the new King Air t u r b o p r o p air-craft . He indicated the impor tance of carefully identifying fu-ture scientific needs for a i rborne a tmospher ic research and using these needs to determine priorities for a fu ture R A F fleet.

Byron Phillips, manager of R A F , discussed the need for the a tmospher ic scientists who are involved in designing and directing a tmospher ic sciences field p rograms to set goals and describe opera t ional capabili t ies for replacement air-craft for the R A F fleet. Funding and acquisit ion of aircraft were seen as separate , administrat ive tasks.

b. Current RAF fleet capabilities

The current R A F fleet then was described: two N C A R Queen Air aircraft , the N C A R Sabreliner, the University of Wyoming King Air (acquired for R A F by lease for six months per year th rough 1986), and the N C A R Electra.

The N C A R Queen Airs have been the workhorses of the R A F fleet for many years. Their ma jo r l imitations include poor per formance in icing si tuations, slow speed, poor climb-ing capabilities, and low ceiling(6000 m). The Queen Airs are used heavily and excel at boundary layer and air mot ion sens-ing research. The l imitations of the Queen Airs instigated the acquisi t ion of the new N C A R King Air a i rcraf t , which will replace Queen Air N304D. The new N C A R King Air will be available for research in April 1983. The King Air has greater weight-carrying capabili ty, longer range, and im-proved speed and al t i tude capabili t ies, including reliable op-erat ion in icing condit ions. Addit ionally, the King Air is not much more expensive to opera te than the Queen Air, when all aspects of operat ion for research use are taken into ac-count . It is currently p lanned that t h e Q u e e n A i r N 3 0 6 D will be retained within the R A F fleet for the indefinite future . (It is necessary to provide the two twin-engine aircraft capabil-ity for the six mon ths the University of Wyoming King Air is not available under the lease agreement.)

The N C A R Sabreliner is a twin-jet, high-speed, medium-to-high al t i tude ( < 1 2 800 m) a i rcraf t . It has modera te range and payload capabilit ies and relatively low operat ing costs. Recent innovat ions on the Sabreliner a i rcraf t have substan-tially increased its research capabilit ies. These developments include a new, improved data system and a r a d o m e gust p robe system, which will provide higher- f requency air mo-tion measurements than were possible previously. The de-mand for Sabrel iner use has increased. The Sabrel iner 's ef-fectiveness is limited by range, its small cabin and al t i tude, and its inability to operate in icing condit ions.

The N C A R Lockheed Electra originally was acquired by N C A R for the Global Atmospher ic Research P rogram— Atlantic Tropical Experiment (GATE) project . It has been used in the Global Atmospher ic Research Program ( G A R P ) exper iments f rom G A T E through the current Alpine Exper-iment ( A L P E X ) . Fol lowing A L P E X , the Electra is expected to be avai lable to the scientific communi ty on a full cost-re imbursement basis, with a one-year notice required pr ior to use. The Electra 's main a t t r ibutes include its large cabin

TABLE 1. Atmospheric science objectives grouped according to horizontal scale.

Planetary scale (104 km) Global tropospheric chemical systems Global biogeochemical studies Global concentration distributions of trace gases Global sources and sinks Long-range aerosol transport processes Stratospheric chemical measurements

Synoptic scale (103 km) Cyclogenesis over the oceans Boundary layer structure of ocean storms Mesoscale hurricane organization Winter cyclonic storms Role of cloud dynamics in storm energy budgets Boundary layer-storm interactions Jet stream and frontal zone deformation Stratospheric-tropospheric exchanges, tropopause folding Reaction pathways (gas-gas, gas-particle)

Large mesoscale (102 km) Organized mesoscale features Mesoscale convective complexes Local circulations Boundary layer structure over complex terrain Regional boundary layer properties Orographic influences on precipitation structures Low-level fronts, boundary layer lids, flux profiles Coastal zones, upwelling, long-term oceanic sampling Open ocean reactions and interactions with storms Ozone distribution Gas-particle conversions

Storm clouds (101 km) Meso-low organization along fronts Storm cloud-environment interactions Entrainment Hydrometeor development Weather modification (stratus, fog, orographic) Coupled cloud physics and dynamics Atmospheric electricity Cloud physics and chemistry interactions Turbulent transport of chemical species Small mesoscale atmospheric phenomena Transport and diffusion in the planetary boundary layer (PBL) Three-dimensional observations: waves, rolls, etc. Surface fluxes over the ocean Inhomogeneous boundary layer Downburst, microburst

Cloud, subcloud {< 1 km) Turbulence Gust front structure Wind shear structure

volume, payload , and electrical power (available for user re-search ins t rumenta t ion) ; its excellent air mot ion measuring capabili t ies; and its extended range. The sum of these attri-butes is not matched with any other large research aircraf t now in opera t ion . Fo r example, compar i son of the Electra capabili t ies with those of the N O A A P-3 aircraf t indicates that the Electra provides superior air mot ion and user equ ipment capabili t ies and that the P-3 provides superior range and rada r capabili t ies, which are a substant ial advan-tage in the study of large oceanic s torms. A ma jo r deficiency of the Electra and of all large research aircraf t is their high cost of opera t ion . Because of the relatively small number of p rograms requir ing large aircraft and because of tight


Bulletin American Meteorological Society 483

TABLE 2. Instrumentation development needs that will be re-quired as part of the airborne scientific research of the next 10-15 years. These needs are derived from the high-priority airborne at-mospheric sciences research projects summarized in Table 1.

Cloud physics Cloud particle photography In-cloud temperature In-cloud humidity and water condensate Liquid/ice discrimination for water condensate High-rate measurement capabilities for temperature, humidity,

and water condensate within cloud Improved air-motion capabilities within cloud and precipitation

Remote probing Doppler radar Doppler lidar Multiwave length polarization diverse radar Infrared scanning radiometers Multiwavelength infrared capabilities for remote temperature

and humidity measurement Microwave radiometers for water vapor, liquid water content,

and in-cloud temperature measurement

Aircraft position Aircraft position to 20-50 m horizontally Aircraft altitude to 10 m

Air-motion measurements Air-motion measurement capabilities good to 1 m resolution Air-motion measurements in cloud and in icing Air-motion measurements made at the same time as airborne

radar measurements Remote probing air-motion measurements

A tmospheric chemistry Reliable, small, unattended measurements of ozone, carbon

monoxide, water vapor, and other chemical species Remote measurements of chemical species

Dropable in-situ sensing systems Improved dropsonde with over-land capability Ocean current measuring system Airborne expendable bathythermograph (AXBT) capability

budgets , N C A R has not been able to jus t i fy f und ing fo r the a i rcraf t .

The University of Wyoming's King Air N 2 U W cloud phys-ics a i rcraf t recently has been made available to the b roader a tmospher ic science communi ty through a lease arrange-ment between N C A R ' s R A F and the University of Wyo-ming. The lease per iod is six months , normal ly f r o m April t h rough September each year, s tar t ing in May 1982 and con-t inuing th rough September 1986. Wyoming ' s King Air air mot ion measur ing capabil i ty has been upgraded substan-tially using an inertial navigat ion unit on loan f r o m N C A R . While Wyoming ' s King Air is a m o n g the finest cloud physics a i rcraf t in the scientific communi ty , it also must be noted that it is in tended to be a mult iuser a i rcraf t and therefore lacks ins t rumenta t ion flexibility in compar i son to the R A F fleet.

The discussion of the current R A F fleet ended with em-phasis on present l imitat ions in conduc t ing scientific re-search. Opera t iona l l imitat ions such as al t i tude, payload , and range can have a significant effect on how research pro-grams are designed. In some cases, these l imitations have se-riously restricted the quest ions that can be addressed in at-mospher ic research programs.

c. Scientific needs for research aircraft

The w o r k s h o p a t tendees were asked to indicate their percep-t ions of the most impor tan t scientific needs for research air-craf t over the next decade, with an emphasis on those needs most closely identified with individual research interests. Fol lowing discussions of these specific interests, the research projects were organized into general categories based on the hor izonta l scale of meteorological interest. (The reason for this s trat i f icat ion is that the type of a i rcraf t and flight pat tern needed is related to the scales of mot ion or scales of a tmos -pheric p h e n o m e n a of interest.) Five scales were selected, as indicated in Table 1. The organiza t ion of the a tmospher ic sciences research projects into the groupings of Table 1 was done without any setting of priorities or just if icat ion of the science.

d. Instrumentation developments

The workshop proceeded to a discussion of expected devel-opmen t s in ins t rumenta t ion . The past 10-15 years have placed extreme demands on research aircraf t in terms of weight, power , and cabin volume. In the near fu ture , we can expect new chemical measuring appara tus , new and im-proved air mot ion measur ing systems, and new develop-ments in a i rborne research microwave and optical remote sensing. The development of such ins t rumenta t ion will place d e m a n d s on the a i rc raf t , and we must be prepared to meet these demands as best as possible.

The workshop at tendees indicated the most impor tan t in-s t rumen ta t ion development needs expected within the next ten years, which are listed in Table 2. Development of air-borne remote probing was placed near the top of the list.

A brief presentat ion on a i rborne Doppler radar tech-niques and testing was made by Peter Hi ldebrand. J o h n Wyngaard suggested that ano ther workshop be planned in the near fu tu re to discuss the potential of, and priorities for , a i rborne remote probing techniques. This was heartily endorsed.

The state of cloud physical ins t rumenta t ion was univer-sally deplored. Aside f rom the development of Particle Measur ing System probes and some recent work on cal ibrat-ing the measurement of liquid water content , little advance in cloud physical ins t rumenta t ion has been made in recent years. Virtually all in-cloud measurements were discussed, including mean and high rate measurement of in-cloud air mot ion , t empera ture , humidi ty , and liquid and ice content . The need fo r accura te mean and high tempora l resolution data was stressed.

The need for significant improvements in chemical in-s t rumenta t ion for a i rcraf t also was discussed. However , the a tmospher ic chemical representatives at the meeting ex-pressed little hope for immedia te widespread improvements .

e. Availability of aircraft for research and development

Concern was expressed that flight hours continually are being cut in order to fu r the r development activities for avia-t ion. The discussion indicated that there always is a t rade-off


484 Vol. 64, No. 5, May 1983

TABLE 3. Aircraft operational capabilities necessary to support the scientific goals of Table 1 and the instrumentational goals of Table 2. Cabin volume is given in terms of equivalence to the familiar Queen Air (QA), King Air (KA), and Electra (EL) cabin sizes.

Altitude Speed Cabin volume Range Endurance Experiment type (km) (m/s) (equiv) (km) (h) Comments

Planetary scale (10000 km) Global tropospheric

chemical systems Global biogeochemical

studies studies 6 100-200 1-2 EL 3000 6 Global concentration 100-200 1-2 EL 3000

distributions of trace gases

Global sources and sinks ̂ Long-range aerosol 9 — KA 1600 6

transport processes Stratospheric chemical 22 200 QA-KA 4800 7

measurements

Synoptic scale (1000 km) Ocean cyclogenesis 1 6 150 EL 2400-5600 6-10 Doppler radar

112 200 KA 2400-5600 6 Doppler radar, dropsonde Boundary layer structure 3 150 KA 5600 10 Doppler radar

of ocean storms Mesoscale hurricane 6 150 EL 5600 10 Doppler radar

organization ( 1 2 200 KA 5600 6 Doppler radar, dropsonde Winter cyclonic storms I 10 150 KA 3000 6 Two aircraft, polarization

diverse radar, Doppler radar

Role of cloud dynamics in 9 100-150 KA 2400 6 Doppler radar storm energy budgets

Boundary layer-storm 6 75-150 1-2 KA 3000 6 Two aircraft, remote interactions boundary layer winds

Jet stream and frontal 15 100 >KA 4000 6-8 Doppler radar zone deformation

Stratospheric-tropospheric 16 — QA-KA — 5-6 exchanges, tropopause folding

Reaction pathways (gas- 12 100-150 1-2 EL 3000 6 gas, particle-particle)

Large mesoscale (100 km) Organized mesoscale 9 75-100 > K A 4000 6-8 Doppler radar/lidar

features Mesoscale convective 6 75-100 KA 2400 6 Flight in icing

complexes (MCCs) 9-10 75-100 KA 2400 5 High Ze penetration , 15 — KA 1600 5 Doppler radar

MCCs, another approach 9-10 100 KA 3000 5-6 13 150-200 KA 3000 5-6 Doppler radar

MCCs, another approach 9 150-200 2 KA 4800 7-10 Two aircraft Local circulations 6 75-100 QA-KA 2400 5-6 Two aircraft Boundary layer over 10 75-100 QA-KA 1600 5 Two aircraft

complex terrain Regional boundary layer

properties Orographic influences on 4-6 75-100 QA-KA 2400 6 Remote sensing of Z«,

precipitation structures • winds, clouds Low-level fronts, boundary

layer lids, flux profiles ( Coastal zones, upwelling, 6 75-100 QA — 4-6 Remote sensing of Z,, r8fC,

long-term oceanic ocean currents sampling

Open ocean reactions and 9 75-100 1-2 KA 5500 7-10 Remote and droppable interactions with storms sensing for ocean

measurements Ozone distribution 9-11 — QA-KA — 4-6 Gas-particle conversions 4-6 — QA — 3-4

(icontinued on next page)



TABLE 3. (C o n t i n u e d )

Altitude Speed Cabin volume Range Endurance Experiment type (km) (m/s) (equiv) (km) (h) Comments

Storm Cloud (10 km) Meso-low organization

along fronts Storm cloud-environment

interactions Entrainment Hydrometeor development Weather modification

(stratus, fog, orographic) Coupled cloud physics

and dynamics Atmospheric electricity Cloud physics and

interactions Turbulent transport of

chemical species Small mesoscale

atmospheric phenomena^ Transport and diffusion in

PBL Three-dimensional

observations: waves, rolls, etc.

Inhomogeneous boundary layer

Surface fluxes over the ocean

10 75-100 KA 5-6

100 KA

100 KA-EL

1600

2000

Good climb ability, flight in icing ability two aircraft

Two aircraft

75-100 KA 1600 5-6 Two aircraft

Cloud, Subcloud (1 km) Turbulence Gust front structure Wind shear

75-100 KA 1600 5-6

between a commi tmen t of funds and staff resources for de-velopment and for research operat ions . Byron Phillips stated that a f te r a decrease in R A F flight hours dur ing past years expressly to save f u n d s fo r acquisi t ion of the new King Air, the total flight hours now are being increased. The current plans are fo r an increase to at least 800 flight hours per year by FY 1984. The need to keep aircraf t available was a con-cern expressed by many of the workshop par t ic ipants . They felt that development activities should be integrated carefully with opera t iona l research activities so that research is not sacrificed to development . It was noted , however, that some ma jo r ins t rumenta t ion developments would just ify tempo-rarily limiting research flight hours slightly in order to provide the new measurement capabili t ies in the fu ture . It also was noted that R A F should have adequa te flight hours for check-ing out newly developed systems and new techniques. This need of ten has been overlooked in the past.

/ Operational requirements

The par t ic ipan ts were asked to state the opera t iona l re-qui rements necessary to meet the scientific needs described in Section 2c and to meet the ins t rumenta t ion and technique development requirements described in Sections 2d and 2e. Table 3 is a synthesis of the individual s ta tements . Many of the scientific research goals require similar a i rcraf t capabili-ties. Fo r example, an Electra-sized aircraf t having an al t i tude capability of 6 km, a speed of « 1 5 0 m / s , a range of ^ 3 0 0 0 km, and an endurance of 10 h, would satisfy all of the large-

ai rcraf t , long-range needs perceived by .the workshop . Presenta t ion of these operat ional requirements for differ-

ent research needs led to a discussion of the value of small a i rcraf t as a supplement to the general research fleet. Despite the applicabili ty of smaller (single-engine) aircraf t for some occasional research requirements , the cont inuing need to mainta in the Queen Air (or smaller-sized a i rcraf t ) for various types of limited studies was endorsed enthusiastically by sev-eral individuals. It was noted that the Queen Air aircraft does an excellent j o b for b o u n d a r y layer studies, including near-shore oceanic a tmospher ic interaction and some smaller-scale regional bounda ry layer studies.

The utility of drones , gliders, and powered gliders for var-ious types of studies was discussed briefly. The consensus was that while these a i rcraf t have interesting at t r ibutes , the development of powered aircraft ins t rumenta t ion capabili-ties would be more effective, except for special research pur-poses when drones and gliders might be necessary for safety reasons.

g. Available aircraft

Bob Burris, chief pilot at R A F , discussed the capabil i t ies of current ly available a i rcraf t , including small, medium, and large t u r b o p r o p aircraf t and small and medium jet a i rcraf t . His presenta t ion was limited to a i rcraf t that are bo th cur-rently well suppor ted within the aircraf t industry and capa-ble of fulfi l l ing the scientific research missions. He presented summar ies of a i rcraf t capabili t ies based on the Business and


486 Vol. 64, No. 5, May 1983

TABLE 4. Summary of available aircraft types and capabilities. The general types are selected by aircraft weight, with an exemplary aircraft given. The aircraft capabilities and specifications are averages of the values for the five to eight different aircraft considered in each group.

Maximum payload— maximum Range Cost

Maximum Payload zero full Range (n.mi)—with Service Service (estimated) Average values gross weight with full weight minus (n.mi)—with maximum ceiling ceiling (ft.) Cabin size (1979 dollars

by weight group (lb) take off fuel (lb) empty weight full fuel IFR payload IFR (ft.) engine out ft3 (millions)

Small twin turboprop Up to 15 000 lb (King Air 200)

13 500 650 3 100 2 000 1000 30000 15 900 610 1.7

Medium twin turboprop 15 000-60000 lb (CV 580)

45 000 4 350 11 500 1550 730 24 400 13 500 2 300 4.8

Large turboprop Over 60 000 lb (Lockheed Electra)

145 000 27 400 34 500 3 400 3 000 30900 22 600 4 700 11.0

Small turbine Up to 25 000 lb (Sabreliner)

18 500 1360 2 900 2050 1650 45 300 24 900 515 4.2

Medium turbine 25 000-70 000 lb (Gulf-stream-II)

53 500 2 350 5 200 3 450 3 150 44 500 27 800 1050 9.5

Commercial Aviation Magazine's h a n d b o o k describing avail-able aircraf t .2

These a i rcraf t categories were considered to be the most likely sources of the a tmospher ic sciences research aircraf t ; o ther a i rcraf t types therefore were not considered. In this re-gard, a category of potentially useful large tw in - tu rboprop a i rcraf t may emerge in the next two to five years, but was not considered due to its current unavailabili ty. The values indi-cated in Table 4 are the average values for var ious available a i rcraf t . Clearly, for any one general a ircraf t capabil i ty, any specific a i rcraf t might have values that are smaller or large than those values printed in Table 4. The purpose of the table, therefore , is to provide guidance as to what capabilities generally are available, given the current a i rcraf t being man-ufactured. Table 5 gives specific details for some sample air-craft in each of the categories listed in Table 4.

h. Matching of scientific needs for research aircraft with available aircraft types

The workshop par t ic ipants then matched the scientific needs for research aircraft with the available aircraft types as indi-cated in Tables 4 and 5. The a tmospher ic sciences research projects of Tables 1 and 3 were sorted according to the type of a i rcraf t , as shown in Table 6. This provides an overview of what types of a ircraf t are most necessary and usable in the

2Business and Commercial Aviation Planning and Purchasing Handbook, 1980 and 1981.

a tmospher ic sciences communi ty . The small twin t u r b o p r o p aircraf t (e.g., King Air) emerges as very heavily used in a wide variety of a tmospher ic sciences research programs. The large t u r b o p r o p a i rcraf t (e.g., P-3 or Electra) remains impor tan t for large-scale and chemical a tmospher ic sciences research p rograms . This suppor t s N C A R ' s procurement of the King Air and the availabili ty of N C A R ' s Electra for selected re-search p rograms despite funding limitations.

The small- and medium-jet categories have capabilities not provided by other aircraft and extend the abilities of R A F considerably in terms of alt i tude and speed. It is clear that the small jet can satisfy many of the small twin t u r b o p r o p needs with only a slight increase in cost to the p rog ram. If modest increases in da ta rate and durabi l i ty are provided, the small jets can make meteorological measurements that approach the resolut ion of the slower propeller-driven a i rcraf t . At the same time, the jets can cover meteorological features of in-terest very quickly and can therefore reduce tempora l effects on the data .

The medium jet is capable of suppor t ing a n u m b e r of the large t u rboprop - type p rograms , specifically, some of the chemical p rograms , hurr icane environment interactions, and studies of oceanic cyclones. Due to the need to sample ahead of the propel lors fo r some types of chemical measurements , the medium jet also may have an "e f fec t ive" cabin volume similar to the Electra. It would provide similar range and greater al t i tude capabilities.

Some par t ic ipants expressed a need for flying regularly and reliably to the lower s t ra tosphere ( « 1 7 000 m) and well into the s t ra tosphere ( ^ 2 1 - 2 3 000 m). The high-al t i tude re-


Bulletin American Meteorological Society

TABLE 5. Similar to Table 4, but providing specific details for a number of aircraft in the various groups.

487

Small and medium twin

Maximum payload—

turboprops maximum Range Service Cost Maximum Payload zero full Range (n.mi.)—with Service ceiling (estimated)

Small twin gross weight with full weight minus (n.mi)—with maximum ceiling (ft.) Cabin size (1979 turboprop (lb) take off fuel (lb) empty weight full fuel IFR payload IFR (ft.) engine out ft3 dollars)

King Air 200 14000 870 2 745 1834 1248 35 000 19150 361 1475 000 Merlin IVC 14000 207 3 049 2120 1000 30000 14 550 634 1845000 HP Garrett

TPE331-3 Jet stream 12 500 850 3 600 2 160 690 25 000 14000 846

Jet stream 31 14 300 Average 1 660000

Medium twin turboprop Fokker F-27 45 200 8010 12 290 1 190 647 20000 9 500 3 029 6 350000 G-1C 36 200 890 7 400 1800 510 12000 30000 1875 3000000

Long-range CV-580 54 600 1900 14000 2 380 1064 25 000 18 000 2065 tanks DHC-7 44000 6 575 12 290 970 690 22 800 14 800 2150

Average 5 020000 4 790000

Large turboprop L-188C

Electra 116000 13 566 27 250 2 670 2 250 30000 19000 5 303 P-3 134000 12 360 26 000 3 385 2 650 28 300 19000 4260 L-100-30C 155 000 46 602 40000 2937 2937 32 600 26000 4 875 11000000 C-130H 175 000 37 252 45 000 4 770 4 197 33 000 26 500 4 500 Sabreliner 60 20000 2 250 2 250 1300 1300 45 000 25 000 543 Sabreliner 60A 22 700 2000 3 300 1620 1300 45 000 25 000 543 Sabreliner 65 23 800 1416 2 550 2407 1977 45 000 24000 543 5 100000 Lear 56 20 500 669 3 294 2 365 1242 51000 . NA 370 3614785 Westwind II

(Israel) 23 500 1070 3 650 2 542 2 172 45 000 29000 359 3 828 060 HS-125-700 24 800 740 2 350 2 200 1980 41000 21600 728

Average 4 181000 Medium turbine Falcon 50 38 000 2 640 3 240 3 165 3 100 45 000 35 000 845 8 750000 Canadair

CL600GE 41600 1400 4 525 3 700 3 040 45 000 25 000 1415 9 900000 Gulfstream II 65 500 2 800 8814 3 361 3 036 43 000 24 300 1037 7 100000 Gulfstream III 68 200 2 600 4 300 3 697 3 422 45 000 27 000 1037

Average 11000000 9 187 500

Very large turbine C-5A 764 500 112 298 265 000 7 460 3 640 38 000 35 000 56 251

search is within the capabil i ty of certain research aircraf t suppor ted by N A S A , e.g., the U-2 and ER-2 a i rcraf t . The po-tential use of drones , gliders, and small , very light twin- or single-engine aircraf t also was discussed for specific applica-tions, a l though these types of aircraf t and their missions clearly were of lower priori ty than the o ther a i rcraf t types discussed because of their more limited and specific applicabili ty.

i. Other aircraft

N C A R ' s R A F is not the only potent ial source of research air-craf t for a tmospher ic sciences within this country . While the purpose of the workshop was to provide r ecommenda t ions for the acquisi t ion of new aircraf t for N C A R and the com-muni ty it serves, the potential use of other aircraf t also was considered. Table 7 lists some of the o ther research aircraf t that are available f rom time to time for use by the a tmos-

pheric sciences communi ty . Several a i rc raf t listed in Table 7, which are of par t icular

interest to the communi ty represented by this workshop, are wor th noting. In part icular , the N O A A P-3-C hurr icane re-connaissance a i rcraf t are the a i rcraf t of choice for low- to mid-level, long-range research missions involving large-scale a tmospher ic s torms. These ai rcraf t penetra te hurr icanes reli-ably, have been used in the G A R P experiments , and have been used profi tably by university investigators.

The N A S A CV-990 is a useful a i rcraf t and has f lown a wide variety of measurement systems, including a Dopp le r lidar air mot ion measur ing system capable of mapping air mot ions within the clear a tmospher ic boundary layer. Many of the ins t ruments f lown on the CV-990 are provided and op-erated by the users.

The N A S A U-2 and ER-2 are the only aircraft known to this g r o u p that are capable of satisfying the 17 000-23000 m research capabili t ies. As such, these aircraf t are of great im-por t ance to the a tmospher ic chemists. The N A S A B-57 also


488 Vol. 64, No. 5, May 1983

TABLE 6. Matching of aircraft category types with scientific requirements.

Small twin turboprop Winter cyclonic storms Role of cloud dynamics in storm energy budgets Organized mesoscale features Mesoscale convective complexes Local circulations Boundary layer structure over complex terrain Regional boundary layer properties Low-level fronts, boundary layer lids, flux profiles Meso-low organization along fronts Storm cloud-environment interactions Entrainment Hydrometeor development Weather modification (stratus, fog, orographic) Coupled cloud physics and dynamics Atmospheric electricity Cloud physics and chemistry interactions Turbulent transport of chemical species Turbulence Small mesoscale atmospheric phenomena Transport and diffusion in the boundary layer Three-dimensional observations: waves, rolls, gust fronts, wind

shear Inhomogeneous boundary layer Surface fluxes over the ocean (near shore) Coastal zones, upwelling, long-term oceanic sampling Long-range aerosol transport processes Ozone distribution Gas-particle conversions

Small jet Jet stream and frontal zone deformation Stratospheric-tropospheric exchanges, tropopause folding Mesoscale convective complexes

Boundary layer structure over complex terrain Ozone distribution Storm cloud-environment interactions Entrainment Hydrometeor development Weather modification Coupled cloud physics and dynamics Atmospheric electricity Cloud physics-chemistry interactions

Medium jet Ocean cyclogenesis Mesoscale hurricane organization Jet stream and frontal zone deformation Stratospheric-tropospheric exchanges, tropopause folding Reaction pathways (gas-gas, particle-particle) Mesoscale convective complexes

Large turboprop Global tropospheric chemical systems Global biogeochemical studies Global concentration distributions of trace gases Global sources and sinks Reaction pathways (altitude limitations) Ocean cyclogenesis Mesoscale hurricane organization Boundary layer-storm interactions Boundary layer structure of ocean storms Mesoscale convective complexes Cloud physics-chemistry interactions

High altitude jet Stratospheric chemical measurements

could provide in situ and remote measurements f r o m high alti tudes.

The par t ic ipants also discussed the availability of several university a i rcraf t , specifically, the South Dako ta School of Mining and Technology T-28, the University of Washington B-23, the University of Nor th D a k o t a Cessna Ci ta t ion, the New Mexico Tech SpitVar, the Co lo rado State University Cessna 207, and the Georgia Tech Convai rs 240 and 260. It was noted tha t , with a few exceptions, these a i rcraf t tend to be single-user a i rcraf t that are available for general research only with the involvement of the parent university staff as a principal or coinvest igator in the research. Since such staff involvement is limited because of teaching and individual re-search work loads , the availability of these a i rcraf t as general suppor t research vehicles also is limited. Nonetheless, the university a i rcraf t are viewed as being of high impor tance to the communi ty . In addi t ion to supplement ing the available research fleet, they are highly valuable for on-site t raining and experience at the university and as mot iva tors for the de-velopment of new ins t rumenta t ion and research techniques.

Together , these other a i rcraf t have many and diverse ca-pabilities and are of significant value to the a tmospher ic sciences communi ty . Of pr ime impor tance is the need to es-tablish a mechanism for using these a i rcraf t . Al though the model set fo r th by N C A R / R A F and the Universi ty of Wyoming certainly is a t t ract ive, it is by no means the only

type of agreement that can make these a i rcraf t available to o ther users. In par t icular , the wide use of the N O A A P-3s for diverse research projects has been extremely successful. There was general agreement of the need to pursue, in part ic-ular, the mechanisms for making available the N O A A P-3s, the NASA U-2s and ER-2, the NASA B-57, and possibly a few other aircraf t to the broader research communi ty . It was felt that R A F could help develop the means whereby well-focused research missions directed by scientists not otherwise con-nected with N O A A or NASA could be f lown on these a i rcraf t .

Larry Lee, a representat ive f rom NSF , commented that a list being developed by R A F in response to an N S F request will include all research aircraft in the country . The list will conta in a brief descript ion of the aircraf t capabilities and will indicate how to contact the agency that owns and operates the a i rcraf t . This system is under development and will be called the Atmospher ic and Oceanographic Research Air-craf t In fo rma t ion System. It is intended that potential users of aircraft will be able to access this informat ion via compute r da tabase techniques.

j. A hypothetical RAF fleet

As a final step in the workshop , the par t ic ipants were asked



to describe a hypothet ical R A F aircraf t fleet that would ful-fill the major i ty of their high-priori ty a i rcraf t needs for the decade beginning circa 1985-86. Table 8 summarizes seven suggested opt ions . There was s t rong sentiment for mainta in-ing the best possible small a i rcraf t capabil i t ies, as exempli-fied by the King Airs, and for retention of the Queen Air for more conservative specific p rograms , including bounda ry layer and o ther low-level p rograms . There was s t rong sup-port for improving the available small- to-medium-jet capa-bilities. The opt ions included improving the Sabreliner with engine and wing modif icat ions , replacing the Sabreliner with a larger medium-range jet , and adding a medium-range jet to the fleet in addi t ion to the Sabreliner. Little in fo rmat ion abou t the costs and benefits of the suggested Sabreliner mod-ifications was presented at the workshop . This precluded an in-depth discussion of the relative values of the Sabreliner, an upgraded Sabrel iner , and a larger medium-range jet . The principal interest in an upgraded Sabrel iner was that this op-tion would notably increase its al t i tude capabil i ty, but would be inexpensive compared to the acquisit ion and modif icat ion costs of a new medium jet.

To separate the opt ions into a more comprehensible pr ior-ity list, two questions were asked of the attendees: What choice would you make for the next a i rcraf t purchase for R A F ? and How should the Electra be funded?

For the next a i rcraf t purchase , the at tendees were asked to show their preference a m o n g a possible Sabreliner upgrade, a new jet (with medium-jet capabilities), and the purchase of an addi t ional King Air. The exact cost and availabili ty of the upgrade to the Sabreliner was not known, 3 but it was thought that it might be smaller than the cost of a new jet of med ium-jet capabilities. In addi t ion, a new jet could be somewhat more expensive to opera te than the Sabrel iner in its present or upgraded conf igura t ion . Of 20 people, nine voted for the upgraded Sabreliner; seven voted fo r the acquisi t ion of the new, more capable jet; and the remaining fou r voted for the acquisi t ion of an addi t ional King Air. Those voting for the Sabrel iner upgrade or the new jet indicated that they would have voted, by and large, for either of those two over the ac-quisi t ion of a second new King Air. This vote clearly indi-cates that the workshop felt that there was a higher priori ty for improvement in the jet capabili t ies at R A F than for the acquisi t ion of a second, small twin t u r b o - p r o p a i rcraf t . The N C A R King Air and Queen Air, plus half- t ime use of the University of Wyoming King Air, were deemed adequa te by the major i ty of the workshop at tendees. These conclusions could be invalid if it were determined clearly that , for example, either or both the N C A R Queen Air and the Wyoming King Air would not be available within the R A F fleet af ter 1986.

An addi t ional discussion, endors ing the acquisit ion of a medium-sized jet, centered on this a i rcraf t ' s potential ability

TABLE 7. Other aircraft that may be available to the atmos-pheric sciences community.

Aircraft Institution

3 The attendees at the workshop did not have enough information to make an accurate comparison between the Sabreliner upgrade and a new jet. This was due to a lack of knowledge of exactly what was available with regard to the Sabreliner upgrade and the need to investigate the mid-jet capabilities and market more thoroughly. It was recognized that such a discussion probably would require a new workshop to address these questions specifically. However, the con-clusion here clearly endorses having such a discussion at a reasonably early date.

P-3-C CV-990 U-2 ER-2 C-130 C-130 Electra P-3-A C-141 B-57 B-23 T-28

Cessna Citation Convair 240 Convair 260 SpitVar

Cessna 207

DeHairland Twin Otter

Sailplane

NOAA, NASA NASA NASA NASA NASA Air Force Weather Reconnaissance NASA NASA NASA NASA University of Washington South Dakota School of Mining and

Technology University of North Dakota Georgia Institute of Technology Georgia Institute of Technology New Mexico Institute of Mining and

Technology Colorado State University Atmospheric Environment Service,

Canada Convective Storms Division (NCAR)

to serve a wide variety of users. Al though it might be slightly more expensive to opera te than the Sabrel iner , it would be less expensive than the Electra and therefore might serve a wider range of users more effectively, considering the limited funds available for research aviation.

The second vote concerned the fund ing basis for the Elec-tra. The opt ions were: total N S F suppor t ; partial N S F sup-por t ; and N S F suppor t to keep the a i rcraf t operable , but not fund any flight hours . Dissension was expressed about taking this vote at all. Many of the par t ic ipants felt that too little was known of the need for long-range a tmospher ic chemistry measurements and therefore they could not vote adequate ly on the use of such an a i rcraf t . The chemists present indicated s t rong potent ia l needs for the a i rcraf t , but no immedia te concrete plans. Of 20 par t ic ipants present , only 13 expressed

TABLE 8. Suggested hypothetical NCAR/RAF fleet composition.

Medium Large Option Queen Air King Air Sabreliner jet turboprop

1 1 1 1/2 1 1* 2 1 1 1/2 1 1 j** 3 1 1 1/2 1 I** 4 1 1 1/2 It 1* 5 1 21/2 It 1 6 Itt 11/2 1 1 1 7 1 1 1 1 1

* Only available on a complete cost-recovery basis. ** It was suggested that an arrangement to use another agency

aircraft would suffice. t Sabreliner, upgraded with new engines to enable penetrating

icing conditions and new wings to enable higher altitude operation.

t t The replacement of the aging Queen Air by a more modern small aircraft of similar capabilities was suggested.


490 Vol. 64, No. 5, May 1983

an opin ion . Two saw the need fo r total N S F suppor t , five felt the Electra should be suppor ted partially by N S F under a plan in which some hours would be base- funded through N C A R / R A F and addi t ional hours would be funded by the individual research p rograms (of N S F or o ther agencies), and six people voted fo r main tenance of the Electra in a ready capabil i ty, but with research projects being expected to br ing in all opera t ional costs of flight activities on the air-craf t . The results of this discussion clearly were inconclusive, except as an il lustration of suppor t for the availability of the Electra. This reflects the turmoil that has sur rounded the Electra dur ing recent years. The conflict between the scien-tific need for the Electra and the budget ing requirements for it is ongoing.

3. Summary of the workshop

After two days of tightly focused thought and discussion, the workshop par t ic ipants reached several noteworthy conclu-sions. First, two areas of aircraft ins t rumenta t ion were pin-poin ted as being in need of a concer ted effor t by the research communi ty : 1) the development of a i rborne remote probing , including Doppler radar , Doppler lidar, and the associated da ta display and processing systems; and 2) the development of ins t rumenta t ion capable of measuring all in-cloud varia-bles, such as winds, t empera ture , humidi ty , and cloud water content . Af ter some expressions of concern over the conflict between the al locat ion of f u n d s for research and the al loca-tion for ins t rumenta t ion development , a t tendees concluded that reasonable t radeoffs can be made. Since developments in ins t rumenta t ion are almost always in direct response to specific scientific research needs, integration of the two ef-for ts , without sacrificing either one, should be possible.

Second, r ecommenda t ions were made for a fu tu re R A F fleet. These r ecommenda t ions endorsed the use of one N C A R King Air, the half-year use of the University of Wyoming King Air, and the retention of the N C A R Queen Air N306D as the workhorses of the fleet. The aircraf t that clearly were identified as having the highest priority for en-hancement were the small- to-medium jet a i rcraf t . The Sabre-liner was endorsed as a very impor tan t a ircraf t that serves critical scientific needs. The weaknesses of the Sabreliner (its inability to opera te in ic ingand its limited al t i tude and range capabili t ies) could be alleviated in large part by replacement with a medium twin-jet aircraft of the Gulfs t ream-II or Canada i r Chal lenger variety. Such an aircraf t would have greater range and cabin volume, but approximate ly the same alt i tude capabilities, as the Sabreliner.

The fate of the Electra remained as unclear a f te r the work-shop as it was before . The scientists clearly placed a high priori ty on being able to use the Electra in certain p rograms for measurements over large space or time scales, or for car-rying large payloads. The capabilities of the Electra for air-mot ion sensing and chemical sampling of the a tmosphere were regarded as unparalleled and very impor tan t . However , the workshop at tendees felt that the funding issues sur round-ing the Electra needed to be resolved between N S F and N C A R adminis t ra t ive heads. Given the choice between the

present mode of base- funding for the small R A F aircraf t and user-funding for the Electra, and base-funding for the Electra and a more restricted use of the smaller a i rcraf t , the at tendees seemed to prefer the present mode of opera t ion.

High priori ty also was placed upon the development of new mechanisms for the use of n o n - N C A R aircraft by U C A R scientists. These aircraf t included the N O A A P-3, the N A S A U-2 and ER-2, the NASA B-57, and other government agency a i rcraf t . The N O A A P-3 a i rcraf t were repeatedly ment ioned as a good example where such coopera t ion has provided impor tan t research benefits.

Acknowledgments. The authors would like to express a special debt to Darrel Baumgardner and Alex Kennel for their extensive and detailed note-taking during the workshop; to Peggy Taylor and Diane Wilson for their assistance in operating the workshop; and to Robert Serafin and Byron Phillips for their encouragement and guid-ance in preparing for and running the workshop. Ms. Shirley Pompili and Ms. Phyllis O'Rourke aided significantly in the editing of the manuscript.

The participants of the workshop must be thanked for the gener-ous donation of their time and financial support in traveling to the workshop and for their care and clear thinking in discussing complex issues. This important step in the decision process will lead to the most appropriate aircraft and instrumentation for meeting the di-verse research needs of the atmospheric sciences. The next steps of analyses and delineation of the aircraft capabilities and instrumenta-tion development needs most appropriate for future research must be accomplished within RAF, NCAR, UCAR, and NSF. Once the plans are outlined, debate and discussion by the research community are urgently needed in the immediate future.

Appendix. RAF Fleet Workshop attendees

Alan Bandy, Drexel University Peter G . Black, Nat ional Hurr icane Research Labora to ry Richard E. Carbone , N C A R Ralph Cicerone, N C A R W. A. Cooper , University of Wyoming Douglas Davis, Georgia Institute of Technology J a m e s Fankhause r , N C A R Carl Friehe, N C A R Andy J . Heymsfield, N C A R Peter Hi ldebrand , N C A R David P. Jorgensen , Nat ional Hur r icane and Experimental

Meteorology Labora to ry Larry Lee, N S F Dona ld Lenschow, N C A R Douglas K. Lilly, N C A R J o h n McCar thy , N C A R Richard Passarelli, Massachuset ts Insti tute of Technology Byron Phillips, N C A R David J . R a y m o n d , New Mexico Inst i tute of Mining and

Technology Larry Rudke , University of Washington Rober t J . Serafin, N C A R Mel A. Shapiro , N C A R Peter Sinclair, Co lo rado State University J o h n Winchester , Flor ida State University J o h n C. Wyngaard , N C A R Edward J . Zipser, N C A R •


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