NOAA Long-term Research Initiative

*Attacking the Hurricane Intensity and Inland Flood Forecast Problem*

Project Summary

1\. Statement of Objectives

This research Initiative attacks a "Grand Challenge[^1]" for tropical
meteorology: to create a system to simulate and predict accurately
hurricane winds and rain. Everyone is familiar with the scenes of
building destruction and flooding associated with a hurricane. While
forecasts of hurricane track have improved during the past decade (Fig.
1a), our ability to forecast hurricane intensity (surface wind speed and
its areal extent and structure) has changed little (Fig. 1b), and we
have insufficient skill in predicting the heavy rain that leads to
floods. This research Initiative envisions and supports the development
of the first hurricane forecast system to accurately predict the wind
and rain that lead to death, and to damage amounting to \$5 billion
annually in the United States (Pielke and Landsea 1998). Addressing the
challenge requires a special focus by the research community on solving
some of hurricane forecasting's most vexing problems.

The goal of this Initiative is to understand and describe the physical
processes that lead to the extreme winds and heavy rain in a hurricane,
and to use this knowledge to develop an integrated hurricane simulation
and forecasting system that produces skillful forecast guidance of
intensity change and rain in hurricanes striking the United States. The
benefits will include better warnings to the public of where and when
the damaging winds and heavy rain occur so appropriate disaster
preparedness actions can be completed, and minimizing unnecessary
preparation costs and evacuations.

Advances in hurricane track forecasting occurred primarily through a
better understanding of hurricane evolution, and continuous development
and enhancement of numerical weather prediction (NWP) modeling systems.
Achieving improvements in intensity forecasts is at least an order of
magnitude more difficult problem than track, requiring understanding and
simulation of the crucial physical processes that determine the inner
core structure at \~1 km in radius, and changes on a time scale of an
hour. Achieving improvements in rain forecasts is yet a more difficult
problem, requiring resolution of convective cores on a spatial scale \~1
km in both radius and azimuth, and their changes on orders of tens of
minutes. This Initiative represents a Grand Challenge problem because of
the need for an NWP model system with an order of magnitude finer
resolution to simulate the physical processes that determine wind
structure and rain that are not now well understood. Accurately
simulating and forecasting these threats would represent a quantum leap
in our ability to protect life and property from hurricanes.

There are four compelling reasons why now is the time for this
Initiative:

i.  research models at ≤2 km resolution are available and are
    demonstrating they can reproduce many of the characteristics of the
    hurricane wind and rain field,

ii. Doppler radars exist on the NOAA aircraft and the ground that can
    provide necessary data to initialize a model at these resolutions,

iii. satellite communications and the high-speed internet will soon
     permit timely delivery of these data to modeling centers for
     assimilation, and

iv. understanding of inner core dynamics, surface fluxes at high winds,
    moisture, and microphysics through analysis of field program data
    sets is at a point where we can design models to reproduce them
    properly at a high resolution.

+-----------------------------------+----------------------------------+
| \(a\)                             | \(b\)                            |
|                                   |                                  |
| ![](media/image1.                 | ![](media/image2.jp              |
| jpeg){width="3.234027777777778in" | eg){width="3.1145833333333335in" |
| height="1.9861111111111112in"}    | height="2.002083333333333in"}    |
+-----------------------------------+----------------------------------+

Figure 1. Official yearly average 48-h (a) track and (b) intensity
forecast errors and trend lines over the period shown for the Atlantic
basin from NOAA Tropical Prediction Center/National Hurricane Center.

The National Weather Service (NWS)/Office of Oceanic and Atmospheric
Research (OAR) Science and Technology Infusion Program (STIP) process
laid out the operational goals for the intensity forecasts over the next
5-10 years. NOAA's National Center for Environmental Prediction (NCEP)
has put together a plan to address the operational goals with base-level
support. This Initiative will enhance that effort by engaging the
research community to address even more ambitious research goals.

2\. Requirements

Representing the physical processes affecting hurricane intensity and
rainfall distribution requires a very challenging set of forecast system
characteristics. A forecasting system typically comprises a numerical
model (or a suite of models interacting with each other), a set of
observations to specify the initial conditions for the model, a data
assimilation system for incorporating the observations into the modeling
framework at that desired resolution, and output products to use in
forecasting and to evaluate the results of the model forecast. This
Initiative will investigate potential components of the forecast system,
which will include the following five requirements.

**(i) Explicit representation in time and space of the moist convective
and vortex adjustment processes in the inner-core region of the storm
and in regions where the storm interacts with its environment.** The
processes important in governing hurricane intensity and rainfall span a
wide range of spatial and temporal scales. The environmental forcing
considerations require a large domain. The vortex response to that
environmental forcing ultimately involves convection on small horizontal
scales in the eyewall and rainband regions. Resolving this
environment-vortex-convection feedback in a numerical model requires
fine horizontal and vertical resolution in the inner region of the
vortex. The role of convection remains important for forecasting these
tropical cyclones even as they move up the east coasts of the U.S. and
Canada, and undergo a transition to potentially damaging, much larger
extratropical storms.

**(ii) An accurate representation of near-surface processes over water
and land to properly represent surface wind, heat, and moisture
interaction with the underlying ocean and land in the extreme wind
conditions found in hurricanes.** Correctly representing these physical
processes requires a forecast system that includes a high-resolution
atmospheric model coupled with an ocean circulation/surface wave model,
a sophisticated land surface model, and improved techniques to represent
microphysical and turbulent processes. The coupled system components add
new issues as well as complexity to the overall system. The performance
of the model components in the high-wind conditions of a hurricane and
at the high resolution required must be optimized. Vertical fluxes of
momentum, moisture, and energy across three interfaces (between the
atmospheric boundary layer and the convection above, between the
atmosphere and the land or ocean, and between the ocean mixed layer and
deeper ocean) must be accurately simulated. Knowledge of these vertical
fluxes is fairly well advanced for light to moderate wind conditions but
is lacking in the high wind conditions of the inner core.

**(iii) An accurate representation of moisture and microphysical
processes in the forecast system to predict the distribution of rain,
ice, and latent heat exchanges**. Another modeling challenge dictated by
physical process considerations is an improved representation of
microphysical processes. Because half of the rain from hurricanes
originates as ice in the upper part of the storm (Marks et al. 1992),
both ice and liquid microphysical processes must be simulated. In
addition, microphysical processes are keys to determining the vertical
distribution of latent heat release in the storm. Most model systems use
simple bulk representations of these microphysical processes, which
poorly represent the rain distribution and misplace the latent heating
in the vertical. Current techniques for simulating these processes
become problematic at very high resolutions. Thus, a new approach must
be explored to treat sub-grid scale processes in very high-resolution
models, including the coupling of microphysics and turbulent mixing.

**(iv) Appropriate assimilation technologies necessary for inner-core
observations in the forecast system.** Due to the fine-scale structure
involved, accurate predictions of intensity change and rainfall require
new observations and assimilation activities. Each forecast system
component (atmosphere, ocean surface wave, ocean circulation, and land
surface) requires an initial condition specification that is both
internally consistent and consistent between coupled model components.

**(v) An optimal forecast framework (i.e., deterministic or
probabilistic) providing the best use of ensemble techniques, and a
measure of confidence in the forecast.** Given the requirement for such
a complex, nonlinear modeling system with multiple components that are
inter-dependent, questions of predictability arise. The optimal forecast
framework (deterministic or probabilistic) for predicting damaging winds
and heavy rain must be developed.

3\. Methods

This Initiative will support research and development activities through
broadened participation of the research community in building a next
generation hurricane forecast system. Model development will be based on
the meteorological community's Weather Research and Forecasting (WRF)
model infrastructure to facilitate intercomparison of results and
promote research and technology that can benefit such operational
modeling centers as NCEP's Environmental Modeling Center (EMC). This
Initiative augments projected NOAA development in its research
laboratories by drawing in non-NOAA expertise from the university
community, international researchers, the private sector, and other
Federal agencies such as the Naval Research Laboratory. It will also
complement and strengthen ongoing and planned U.S. Weather Research
Program (USWRP) Hurricane Landfall (HL) sponsored research and
technology transfer, e.g., Joint Hurricane Testbed (JHT), NASA
Convective and Moisture Experiments (CAMEX), Office of Naval Research
(ONR) Coupled Boundary Layer Air Sea Transfer (CBLAST) program, and The
Observing-system Research and Predictability Experiment (THORPEX).
Advances from the proposed research could also benefit NWP development
in other U.S. and international tropical cyclone meteorological
services, including the U.S. Fleet Numerical Meteorology and
Oceanography Center.

These activities require the implementation of a forecast system test
capability such as envisioned for the OAR Forecast Systems Laboratory
(FSL) high-performance computer or run on such other state-of-the-art
computer technology as the Japanese Earth System Simulator.

4\. Merit

This Initiative is based on research and operational performance
measures. The NWS/OAR STIP identified a 48-hour intensity forecast error
goal of 13.9 kt for operations by 2012 (12-20% improvement over current
levels) that could be obtained if all available resources were directed
to this problem. The intensity forecast goal for this Initiative is more
ambitious, calling for a 20-33% improvement in a research mode over
current skill levels from 24-48 hours, with a doubling of the
probability of correctly forecasting rapid intensification of tropical
cyclones (currently no greater than 40%). The STIP did not adopt a
forecast error goal for hurricane rain because verification standards
for hurricane rainfall forecasts are only now being developed. However,
the current improvement rates in the skill of overall warm-season rain
forecasts exceeding 1 inch is about 1% per year. The target for this
Initiative is to double that rate of improvement in tropical cyclones
and achieve a 20% increase in skill in a research mode by 2014. To
achieve the forecast goals requires addressing the five requirements. In
turn, each of the requirements is also a scientific or technological
metric. The accelerated scientific and technical advances made through
fuller involvement of the research community constitute other important
measures of the success of this Initiative.

5\. Impacts

NOAA issues official U.S. forecasts and warnings for hurricanes over the
Atlantic and eastern North Pacific hurricane basins, near Hawaii and
Guam, and, by international agreement, forecast guidance for the
remainder of the Americas and Caribbean. NOAA NWP guidance is also
available to the U.S. Joint Typhoon Warning Center which has U.S.
tropical cyclone forecast responsibility for the remainder of the globe.
Three forecast quantities critical for public safety and the
(inter)national economy are: storm position (track), intensity, and
rain. Accurate track forecasts help identify the areas and people at
risk and the time available to prepare. Intensity forecasts are directly
related to the prediction of the location and duration of strong winds
which can cause massive ocean waves, storm surge, and widespread damage.
Hurricane rain forecasts are critical because flood-inducing rains were
responsible for more than half the U.S. hurricane-related deaths over
the past 30 years and more than 10,000 fatalities in a single Central
America storm.

Improvements in hurricane intensity and rain forecasts will benefit most
sectors of society. These forecasts are of critical use to such decision
makers as emergency managers at the local, state, and (inter)national
levels, mariners including the U.S. Navy, NASA, and other U.S. federal
agencies responsible for the well being of millions of people and
billions of dollars of assets. It is estimated that achieving the
intensity forecast goals of this Initiative will save as much as \~\$19
million in preparedness costs, per event, for landfalling hurricanes in
the contiguous United States. This cost is a result of emergency
managers preparing communities for hurricanes one category stronger than
forecast because of current limitations in forecasting hurricane
intensity (e.g., Fig. 1b). This estimate implies the cost of the
Initiative would be recovered 3-9 years after full operational
implementation (Appendix). The savings can also be interpreted as a
\~20% reduction of the "false alarm" rate for evacuations. Reducing
unnecessary evacuations could result in such secondary benefits as
minimizing the chance for loss of life in traffic "gridlock." Advances
in rain forecast skill could save 10-15 lives each year in this country,
with the potential of saving many more lives in some situations.

While this Initiative focuses on wind and rain, the associated advances
through improved understanding, observation, and simulation of the
hurricane structure and environment, and their interaction will lead to
more accurate track forecasts, which are essential for improved wind and
rain forecasts.

Table of Contents

A. Project Description [1](#__RefHeading___Toc444699009)

1\. Introduction [1](#__RefHeading___Toc444699010)

2\. Results from Previous Research [2](#__RefHeading___Toc444699011)

a\. High horizontal resolution requirement
[2](#__RefHeading___Toc444699012)

b\. Surface flux representation requirement
[4](#__RefHeading___Toc444699013)

c\. Improved moisture and microphysics understanding requirement
[6](#__RefHeading___Toc444699014)

d\. Advanced application of inner-core data requirement
[7](#__RefHeading___Toc444699015)

e\. An optimal forecast framework requirement
[8](#__RefHeading___Toc444699016)

3\. Science Plan [9](#__RefHeading___Toc444699017)

a\. Evaluating an enhanced simulation and forecast model system
[10](#__RefHeading___Toc444699018)

b\. Probabilistic approaches versus deterministic modeling
[11](#__RefHeading___Toc444699019)

c\. Improved use of inner core observations
[11](#__RefHeading___Toc444699020)

d\. Analysis, evaluation and validation
[12](#__RefHeading___Toc444699021)

e\. Observations and instrumentation developments
[14](#__RefHeading___Toc444699022)

f\. Transition to operations [16](#__RefHeading___Toc444699023)

g\. Program management [17](#__RefHeading___Toc444699024)

h\. Schedule and interim milestones [17](#__RefHeading___Toc444699025)

i\. Deliverables [18](#__RefHeading___Toc444699026)

j\. Relevance of work and synergistic activities
[18](#__RefHeading___Toc444699027)

B. References Cited [18](#__RefHeading___Toc444699028)

C. Proposal Budget [22](#__RefHeading___Toc444699029)

1\. Cumulative budget [22](#__RefHeading___Toc444699030)

2\. Annual budget [23](#__RefHeading___Toc444699031)

3\. Justification [23](#__RefHeading___Toc444699032)

D. Current and Pending Support [24](#__RefHeading___Toc444699033)

E. Facilities, Equipment, and Other Resources
[24](#__RefHeading___Toc444699034)

Expendables [24](#expendables)

F. Acknowledgement [24](#__RefHeading___Toc444699036)

Appendix [26](#__RefHeading___Toc444699037)

A. Project Description[]{#__RefHeading___Toc444699009 .anchor}

1\. Introduction[]{#__RefHeading___Toc444699010 .anchor}

The NOAA Research Council defined short-term research, long-term
research, and research-to-operations goals. This Initiative focuses on
long-term research to provide underlying knowledge and techniques with
potential to be incorporated by operational centers in future
generations of data acquisition, assimilation, and numerical forecast
systems beyond four to five years. It addresses NOAA's Strategic Plan
Mission Goal 3 ("Reduce Society's Risks from Weather and Water
Impacts"), Strategy 2 ("Understand and Describe"). The Initiative
outlines a plan for NOAA within the next ten years (2005-2014) to
develop the means to predict accurately the processes within hurricanes
that cause damage and death through high winds and heavy rains. That
system must include new methods of obtaining and assimilating massive
amounts of data

Available operational models forecast the track of a poorly resolved,
quasi-balanced vortex that interacts crudely with its environment. As a
result, current numerical guidance products offer virtually no ability
to predict the distributions of high winds and rain in hurricanes. For
example, none of the current numerical model guidance captured the rapid
intensification and the rapid decay before the landfall of Hurricane
Lili (2002) in the Gulf of Mexico, which are the same shortfalls that
occurred with Hurricane Opal in 1995. In both instances, preparations
occurred over a broader area than would have been necessary if a more
accurate intensity forecast had been available.

Recent advances in computer capacity and modeling techniques now permit
the simulation of tropical cyclones in research models with nested grid
resolutions as fine as 1-2 km. The problem is far more complex, however,
than simply running an existing hurricane model on a more powerful
computer. The extreme environment created by a tropical cyclone, coupled
with the ability to describe features at resolutions not previously
available, necessitates the development of modeling approaches with
innovative subgrid-scale physical parameterizations, improved numerical
techniques, and the commensurate understanding of the physical processes
active at these resolutions.

Several important features of tropical cyclones justify these
requirements. For example, the hurricane model must be able to simulate
the development and breaking of unstable vortex-Rossby waves in the
eyewall (e.g., Montgomery and Kallenbach 1997; Schubert et al. 1999).
This will require a fully three-dimensional turbulence scheme because
the horizontal shears in the eyewall region and around convective cells
are very strong and capable of producing resolvable turbulence. It will
also require development of new turbulence closures to handle the
partial resolution of the boundary layer turbulence that should occur on
these fine grid meshes.

Hurricanes draw energy from the ocean and cool the ocean by wind-induced
surface fluxes and vertical mixing in the ocean. The extreme high winds,
intense rainfall, large ocean waves, and copious sea spray push the
surface-exchange parameters for temperature, water vapor, and momentum
into untested new regimes. Air-sea interactions in the eyewall region
are largely unknown, due primarily to a lack of observations at the
air-sea interface. The heat, moisture, and momentum exchange
coefficients under the high-wind conditions are difficult to determine.
For example, the stress is supported mainly by surface waves in the
wavelength range of 0.1-10 m, which are largely unresolved by present
wave models. Parameterizations of these short waves in the spectral tail
and their effects on drag coefficients and air-sea fluxes are needed in
the coupled atmosphere-wave-ocean models. Partially resolvable boundary
layer secondary circulations further modulate surface fluxes and must be
included in new parameterizations.

Similar uncertainties remain in existing microphysics formulations,
partly because of lack of observations to calibrate the schemes.
Preliminary modeling results at ≤2 km resolution indicate that
microphysical parameterizations are sensitive to whether or not the
convective up- and downdrafts are correctly represented in the model,
and this is a grid-resolution problem. The effects on ice nucleation
processes by mineral dust (e.g., Saharan Air Layer) are also not
understood.

Predicting these small, transient features and details of the
interactions with the larger-scale environment, while not possible with
the current operational models, is essential to accurately predict the
processes within hurricanes that govern the magnitude and distribution
of high winds and heavy rain (i.e., storm structure). Such a forecasting
system should meet special requirements. The proposed scientific and
technological development will address these requirements:

(i) Explicit representation in time and space of the moist convective
    and vortex adjustment processes in the inner-core region of the
    storm and in regions where the storm interacts with its environment;

(ii) An accurate representation of near-surface processes over water and
     land in the forecast system to properly represent surface wind,
     heat, and moisture interaction with the underlying ocean and land
     in the extreme wind conditions found in hurricanes;

(iii) An accurate representation of moisture and microphysical processes
      in the forecast system to predict the distribution of rain, ice,
      and latent heat exchanges;

(iv) Appropriate assimilation technologies necessary for inner-core
     observations in the forecast system; and,

(v) An optimal forecast framework (i.e., deterministic or probabilistic)
    providing the best use of ensemble techniques, and a measure of
    confidence in the forecast.

To include environmental forcing and resolve the fine structures of the
hurricane inner core and rainbands, a vortex-following, nested grid
within a large domain is needed. Although 1-2 km horizontal resolution
may be able to represent the inner core, as well as high winds and
intense rain in hurricanes, a research model that is capable of
performing well at even higher resolutions for the purpose of developing
and testing new, improved subgrid-scale parameterizations of turbulence,
microphysical, and air-sea-land coupling processes must be evaluated.

As noted above, while this Initiative focuses on wind and rain, the
associated advances through improved understanding, observation, and
simulation of the hurricane structure and environment, and their
interaction will lead to more accurate track forecasts, which are
essential for improved wind and rain forecasts.

2\. Results from Previous Research[]{#__RefHeading___Toc444699011
.anchor}

a\. High horizontal resolution requirement
[]{#__RefHeading___Toc444699012 .anchor}

Recent progress in the research community indicates the critical
processes responsible for hurricane intensity change and rainfall can be
modeled numerically. To do so requires an advanced set of model system
characteristics. The NOAA operational hurricane model, originated at the
Geophysical Fluid Dynamics Laboratory (GFDL), currently has a horizontal
resolution of \~18 km. Plans at NCEP/EMC for upgrading the operational
hurricane forecast system focus on developing a version of the WRF model
for application to the hurricane forecast problem (HWRF, Surgi and Evans
2003). HWRF will be a high-resolution, next-generation
atmosphere-ocean-land prediction system. The forecast system will
include advanced physics and coupling to a nested surface wave model and
a land system couple to hydrology. The HWRF will make use of advanced
observational systems (e.g., the 1000-fold increase in satellite-based
observations and the FY2003-04 NOAA Marine and Aviation Operation budget
initiative to upgrade the NOAA aircraft instrumentation), and data
assimilation techniques for the large-scale environment, and the
hurricane inner-core circulation. Similar to the GFDL model, the HWRF
will be a nested movable mesh model. By 2006, HWRF implementation will
run at 13 km horizontal resolution and 42 levels in the vertical, with
incremental resolution increases in the horizontal to 5-7 km and 64
vertical levels by 2010.

These horizontal resolutions are known to be inadequate for fully
resolving the damaging winds and heavy rain in the eyewall and rain
bands. To resolve the inner-core structure and dynamics requires a model
horizontal grid resolution ≤2 km. A recent series of high-resolution
model simulations of tropical cyclones was conducted using fully
nonlinear, nonhydrostatic, primitive equation mesoscale models, such as
the Pennsylvania State University (PSU) and National Center for
Atmospheric Research (NCAR) Fifth Generation Mesoscale Model (MM5). For
the first time, such simulations demonstrated the ability of
high-resolution models to reproduce the fine structures in the inner
core and outer rainbands region of tropical cyclones (e.g., Liu et al.
1997; 1999; Braun and Tao 2000; Braun 2002; Rogers et al. 2002a, b; Chen
et al. 2002a, b; Chen and Yau 2001; Tenerelli and Chen 2002; Zhang et
al. 2002). Tenerelli and Chen (2001) developed a vortex-following
nested-grid using the nonhydrostatic MM5 that allows long integration
(5-7 days) with very high grid resolution (\~1-2 km) in the inner core
region of hurricanes. They used four-level nests with 45, 15, 5, and
1.67 km grid spacing, respectively. The three inner domains move
automatically with the storm. The model has been used successfully to
simulate aspects of Hurricane Bonnie (1998) (Rogers et al. 2002a, b),
Hurricane Georges (1998) (Orndorff et al. 2002), and Hurricane Floyd
(1999) (Chen et al. 2002a, b; Tenerelli and Chen 2001, 2002) that are
not represented in operational hurricane models. For example, a
high-resolution model was able to capture the development of the
observed concentric eyewalls and eyewall-replacement cycle in Hurricane
Floyd. Tenerelli and Chen (2002) show that a secondary rain maximum and
associated ring of potential vorticity precede the development of the
secondary wind maximum.

The importance of using high resolution to better simulate storm
structure is seen in Fig. 2. Figures 2a and 2b show model-simulated rain
fields at 15-km and 1.67-km horizontal grid resolutions, respectively.
The model with 1.67 km resolution effectively captured the intense rain
in the inner core seen in NOAA WP-3D lower fuselage radar data (Fig. 2c)
at the same stage of storm evolution. The 15-km model depiction doesn't
resolve the inner core and rainband structures.

A 1.3 km MM5 simulation of Hurricane Bob (1991) by Braun (2002) captured
the detailed dynamic and thermodynamic structure in the inner-core
region. The key structures that contributed to the damaging winds and
the heavy rain were identified in that simulation. Snapshots from the
Bob simulation of invertible moist potential vorticity (IMPV, defined by
Schubert et al. 2001) showed that the hurricane eyewall is a ring-like
region of enhanced cyclonic IMPV (Montgomery, personal communication).
The simulated eyewall has an approximately elliptical shape with a major
axis that rotates around the center. The simulation showed that the
major axis angular velocity was approximately one-half the mean
tangential wind at the radius of maximum potential vorticity, which is
consistent with vortex Rossby-wave theory. The strongest convection
occurred along the ends of the major axis of the eyewall wave, with the
eyewall comprising even smaller-scale (\~5-10 km) structures (eyewall
mesovortices). These mesovortices generate local horizontal wind speeds
exceeding the corresponding axisymmetric mean wind speed by 30%. In
addition, the eyewall mesovortices mix high equivalent potential
temperature air. By entraining this highly entropic air, the eyewall
convection is invigorated, and thus eyewall mesovortices act as heat
pumps that help fuel the convection in the eyewall (Persing and
Montgomery 2003).

Research shows that fine-scale structure must be considered in the
context of the interactions of the tropical cyclone with its
environment. In particular, the effects of vertical wind shear play a
critical role in storm intensity and rain forecasts. Interactions with
vertical wind shear are an important part of current statistically-based
intensity forecast models and have been the subject of considerable
research (e.g., DeMaria 1996; DeMaria and Kaplan 1994, 1999; Gallina and
Velden 2002). Frank and Ritchie (2001) and Rogers et al. (2002b) show
that the impacts of vertical shear on both inner-core

+-----------------------------------+-----------------------------------+
| \(a\) MM5 at 15 km                | \(b\) MM5 at 1.67 km              |
|                                   |                                   |
| ![](media/image2.pct)             | ![](media/image2.pct)             |
+-----------------------------------+-----------------------------------+
| \(c\) WP-3D Radar                 |                                   |
|                                   |                                   |
| ![](media/image3.                 |                                   |
| png){width="2.0034722222222223in" |                                   |
| height="1.8618055555555555in"}    |                                   |
+-----------------------------------+-----------------------------------+

Figure 2. Comparison of MM5 simulated surface rain in Hurricane Floyd
(1999) at (a) 15 km and (b) 1.67 km resolutions, and (c) NOAA WP-3D
lower fuselage radar image for the corresponding time (Chen et al.
2002b).

structure and rainfall patterns of tropical cyclones are significant.
Current operational models give reasonably good predictions of storm
environmental vertical wind shear. A more significant problem is the
simulation of the interaction of tropical cyclones with tropospheric
troughs. This interaction is currently not well simulated, despite
recent progress in understanding this issue (e.g., Davis and Bosart
2001, 2002; Hanley et al., 2001). Higher resolution and better
representation of physics in the inner-core region are needed to give
improvements, preferably using a moving, nested grid model.

b\. Surface flux representation requirement
[]{#__RefHeading___Toc444699013 .anchor}

Several recent studies emphasized the importance of air-sea interactions
in tropical cyclone evolution (e.g., Shay et al. 2000, Bosart et al.
2000, Bender and Ginis 2000). Many current tropical cyclone dynamical
forecast models use fixed sea-surface temperatures (SST) as the lower
boundary condition (e.g., DeMaria and Kaplan 1999). Progress has also
been made on more sophisticated representations of the ocean such as
coupled ocean-atmosphere models for tropical cyclones (Bender and Ginis
2000, Bao et al. 2000, Shen and Ginis 2001, Chen et al. 2002b). Radar
altimetry from the NASA JASON-1 and the European Research Satellite-2
missions provide the surface height anomaly (SHA) field and can be used
to estimate Ocean Heat Content (OHC), which is included as a parameter
in the Statistical Hurricane Intensity Prediction System (SHIPS, DeMaria
and Kaplan 1999). Mainelli et al. (2002) found improved intensity
forecasting of up to 5% using pre-storm OHC for Atlantic storms from
1997-2001. Jacob et al. (2000) and Jacob and Shay (2002) used data from
Hurricane Gilbert to assess terms used in various bulk ocean mixed layer
(OML) treatments in models. Thermal advection by the currents and
vertical current shear (entrainment heat flux) significantly affected
the OML budgets and hence OHC variations. Jacob et al. (2002) tested
turbulent ocean mixing schemes using the same initial conditions and
atmospheric forcing and found differences in the magnitude and areal
extent of the response and significant differences in the surface heat
fluxes. Observations acquired from research flights in Hurricanes
Isidore (2002) and Lili (2002) represent prototypes for use in the
development and evaluation of the oceanic and coupled models as well as
process-oriented studies of the ocean forcing over the northern boundary
of the Loop Current.

Surface heat and moisture fluxes from the ocean in high wind conditions
associated with tropical cyclones are unknown. The correct formulation
of wave-age and stability dependence of transfer coefficients for heat,
moisture, and momentum at high wind speeds is also not known because
there are presently few observations of transfer coefficients at high
wind speeds. It has been realized recently that the production of sea
spray in high wind speed regions can have an effect on the transfer of
energy from the ocean surface to the cyclone even as many indirect
observations suggest that the exchange coefficients level off or
decrease above tropical storm-force winds (e.g., Frank, 1984; Powell et
al., 2003). Andreas and Emanuel (2001) suggest that sea spray can
significantly enhance enthalpy transfer. Bao et al. (2000) have shown
that the MM5 simulation of Hurricane Opal (1996) is sensitive to sea
spray. Their results also demonstrate a complex behavior, with the
effects of the sea spray on sensible and latent heat fluxes acting in
opposite senses as the amount of the spray increases. Proposed
parameterizations of this effect give quite different impacts on the
intensity change of tropical cyclones (Fairall et al. 1994; Andreas and
Emanuel 1999; Bao et al. 2000; Wang et al. 2001; Chen et al. 2002b).
Chen et al. (2002b) used the coupled MM5-WAVEWATCH III (Tolman, 1991,
1999) modeling system to show that simulations of Hurricane Floyd (1999)
intensity varied by 10-15 m s^-1^ by varying wind-wave coupling
parameterizations (Fig. 3). The sensitivity increases at higher
resolutions (e.g., \~1.67 km).

Ocean surface wave processes can affect hurricane intensity.
Hurricane-forced ocean surface peak waves reaching 20-30 m are observed!
These large waves affect shipping and fishing interests, especially when
hurricanes move out of the tropics towards the northeast U.S. and Canada
(e.g. Bowyer 2000). The amplitude of these waves is governed by both the
surface wind distribution associated with the hurricane and its forward
motion.

  ------------------------------- ----------------------------------------------------
  Figure 3. Simulated storm       ![](media/image4.jpeg){width="3.566666666666667in"
  maximum wind speed (m s^-1^)    height="2.6527777777777777in"}
  for Hurricane Floyd (1999)      
  using coupled MM5-WAVEWATCH III 
  with two wind-wave              
  parameterizations, compared     
  with an uncoupled simulation    
  (Chen et al. 2002b).            

  ------------------------------- ----------------------------------------------------

Early land surface models arbitrarily cut off surface evaporation at
landfall and changed only the surface roughness. The GFDL model
currently uses a bulk representation of the land surface in which
potential evaporation is reduced via a cooled land surface. A
comprehensive land surface model was collaboratively developed by NCEP,
the University of Oregon, the U.S. Air Force, and the NOAA/NWS Office of
Hydrology. Various configurations of this model are currently being
tested at NCEP to account for changes in the surface fluxes as storms
make landfall over various underlying surface types (Surgi, personal
communication). The land model includes multi-layer interactions between
vegetation, evaporation, soil moisture, temperature, and canopy water
content. These processes are important for storms making landfall over
regions that include standing water. Shen et al. (2002) showed
substantial changes in the surface fluxes. They show the sensitivity for
the 48-h intensity forecast for the landfall of Hurricane Helene (2000)
to the tropical cyclone translating over a nearly dry surface versus a
saturated surface.

c\. Improved moisture and microphysics understanding requirement
[]{#__RefHeading___Toc444699014 .anchor}

These state-of-the-art numerical simulations suggest there is an
intricate interplay between vortex and thermodynamic processes in the
eye and eyewall regions of intense hurricanes. These kinds of
comparisons can only be made, and models evaluated, with special
observations collected in NOAA hurricane research flights. Over the past
15 years, data collected by NOAA WP-3D aircraft during research missions
in hurricanes led to the three-dimensional kinematic and dynamic
descriptions of the inner cores of several hurricanes (Marks 2003).
These analyses were achieved after the development of several data
analysis tools, including wind field synthesis from Doppler data and
larger scale analyses from merging dropsonde data with other data sets
(e.g., Franklin et al. 1993). The three-dimensional analyses confirmed
and extended earlier descriptions of tropical cyclone structure,
especially the secondary circulation in the eyewall, the eyewall
replacement cycle, and the interaction between the inner-core and the
environment.

Additional research has been done on the microphysical structure of
hurricanes, using a combination of flight-level data, airborne radar,
and microphysical probe measurements (e.g., Marks et al. 1992; Houze et
al. 1992; Gamache et al. 1993; Black et al. 1994; Heymsfield et al.
2001). A number of uncertainties remain in the existing microphysics
formulations, partly because of lack of observations to calibrate the
schemes. However, the NASA-sponsored CAMEX-3 and 4 field programs during
1998 and 2001 provided valuable datasets for both model validation and
development. A number of modeling and observational studies using CAMEX
data sets are underway to understand the physical processes controlling
the microphysical properties, including the hydrometeor distributions in
tropical cyclones, and to evaluate, and subsequently validate, the
high-resolution model simulations. Rogers et al. (2002b) and Black et
al. (2002) used MM5 simulations of Hurricane Bonnie (1998) to compare
the results to observed microphysics characteristics and vertical
velocities. There are several similarities in the distribution and
strength of the vertical motions between the simulation and
observations. The majority of vertical motions are weak (between --2 and
2 m s^-1^), and 2-5% of the vertical motions in the eyewall are strong,
with values around 8 m s^-1^. Several significant differences were also
noted, in particular a tendency of the model to under-represent
low-level updrafts. This difference may reflect problems in the
production of hydrometeors and the specification of hydrometeor fallout
in the parameterization scheme.

Comparisons were also made between observed microphysics characteristics
from the NOAA WP-3D and NASA DC-8 penetrations into Hurricane Bonnie
(1998) and an equivalent sample from the simulation of Rogers et al.
(2002b). These comparisons showed that the model tends to produce more
ice and rainwater for stronger upward motions than is observed.
Microphysics data show very little correlation between upward motion and
rainwater mixing ratio, with mixing ratio values around 0.2 g kg^-1^ for
all values of upward motion. On the other hand, values of simulated
rainwater mixing ratio approach 1.6 g kg^-1^ for the strong vertical
velocities and have a strong positive correlation between upward motion
and rainwater mixing ratio. These differences are evidence of possible
problems in the specification of hydrometeor production and/or fallout
in the parameterization scheme. It should be noted that observations
from other cases have a different relationship between rainwater mixing
ratio and vertical motion. For example, probe data from Hurricane Emily
(1987) (Black et al. 1994) have strong negative correlations between
rainwater mixing ratio and vertical motion in the eyewall of the storm,
with a zero correlation in the stratiform region of the storm. Such
differences between storms indicate the complexity of the problem and
emphasize the need for continued research in developing microphysical
schemes appropriate for tropical cyclone environments.

Other studies identified similar problems with current microphysical
schemes. For example, McFarquhar and Black (2002) examined in-situ
microphysical data collected from Hurricane Norbert (1984) and Emily
(1987) and found that the way in which the mass-weighted fall speed of
frozen hydrometeors is specified may be incorrect for tropical cyclone
environments. They derived a new representation for tropical cyclone
size distributions that has significant impacts on the calculation of
the hydrometeor fall speed.

Recent work by Dunion and Velden (2003) indicates that low humidity and
high vertical wind shear associated with the Saharan air layer may limit
tropical cyclone intensification. The large geographical extent of this
phenomenon requires further understanding and tools to identify and
accurately represent the physical characteristics.

d\. Advanced application of inner-core data requirement
[]{#__RefHeading___Toc444699015 .anchor}

The initialization of the hurricane vortex is one of the biggest
scientific challenges in tropical cyclone modeling. The NCEP Global
Forecast System (GFS) makes use of three-dimensional variational
analysis (3D-var) in the Global Data Assimilation System (GDAS), and the
regional model (the GFDL hurricane prediction system) runs off the GFS.
For the GFS, Number range CHAPTERNCEP abandoned inserting synthetic data
(except where the cyclone circulation is particularly diffuse) in favor
of a first-guess field based on real-time storm center locations
provided by the National Hurricane Center (NHC) because of the negative
impact of the synthetic data on the larger scale tropical environment,
including the environmental steering flow. To address the initialization
problem, NCEP/EMC has been developing an advanced data assimilation
capability for the hurricane core circulation that will make use of new
instrumentation on NOAA G-IV aircraft.

Work continues on using various mesoscale initialization techniques in
high-resolution research simulations of hurricanes. Lee et al. (2003)
developed a method of deriving vertical motion in the inner-core of a
tropical cyclone using winds obtained from Ground-Based Velocity Track
Display (GBVTD) analyses of Doppler radar. In this method, the vertical
motion is deduced from the tendency and spatial variations in the
vorticity field. The total balanced three-dimensional wind field is then
obtained using a technique known as Bounded Derivative Initialization
(Lee and MacDonald 2000). These fields are assimilated into the model
over a period of several hours, which allows for the development of the
temperature and moisture perturbations in the model. This technique was
tested by assimilating the wind fields obtained from GBVTD analyses of
Hurricane Danny (1997) into a 1.5 km MM5 simulation. Nuissier and Roux
(2003) and Nuissier et al. (2003) have developed another technique for
initializing a hurricane vortex using wind fields obtained from Extended
Velocity Track Display (EVTD) analyses of airborne Doppler radar (Roux
and Marks 1996). In their technique, the axisymmetric-mean tangential
velocity field produced by the EVTD analysis is used to derive
thermodynamic anomalies from thermal wind balance. The Holland (1980)
wind profile is used to extend the wind fields to a radius sufficient
for properly deriving the thermodynamic fields. This balanced vortex is
then inserted into the model, after having removed the shallow, weak
vortex provided from the global model initial conditions (Kurihara et
al. 1995). Nuissier et al. (2003) tested this technique in a simulation
of Hurricane Bret (1999) using the French mesoscale model Méso-NH at a
grid length of 1.67 km. Similar to the Lee et al. (2003) results, the
initial simulated track and intensity were considerably improved using
this technique.

Over the past several years, NCEP has made significant advancements in
the assimilation of satellite data in the analyses of the tropical
cyclone environment. For example, data from the Advanced Microwave
Sounder Unit (AMSU-B) have been inserted and physical initialization of
the large-scale tropics has been improved with the rainfall rates from
the Special Sensor Microwave/Imager (SSM/I) and Tropical Rainfall
Measurement Mission (TRMM) data. In combination with other modeling
advances, these improvements have led to better hurricane track
forecasts. Currently, 99% of data in NCEP models are derived from
satellites. It is estimated that it takes two years preparation time for
the data from each instrument to be operationally utilized, which is 40%
of the expected instrument lifetime (Surgi, personal communication). To
meet this challenge from both a scientific and increased data handling
and management perspective, NOAA and NASA have recently formed a
comprehensive collaboration effort, the Joint Center for Satellite Data
Assimilation (JCSDA), to expedite the assimilation of satellite data in
operational models. Activities supported by this Initiative will
complement and draw from the JCSDA.

Some atmospheric model data assimilation techniques assume a perfect
model, allowing the assimilation process to alter only the initial
conditions ("strong constraint variational assimilation"). Bennett et
al. (1996), Leslie et al. (1998a, b), and LeMarshall and Leslie (1998)
applied a "weak constraint" system to tropical cyclone forecasting,
which does not assumes a perfect model. That system assimilated cloud
drift winds to improve the larger scale vortex structure and
environment, leading to a significant reduction in model track error.
This approach is currently too computationally expensive for operational
implementation, but further scientific and technical development could
lead to improved hurricane forecasts.

Ocean data assimilation, now in its infancy, is important for better
representing the air-sea fluxes in the coupled model systems, to include
processes in the mixed layer, and to account for the oceanic heat
content. For ocean observations, a simple nudging assimilation technique
is currently being tested in operations at NCEP, and by 2008 NCEP will
use a 3D-var (Surgi, personal communication). The coupling of the land
surface to the GFDL model is underway at NCEP and this technology will
be transferred to the HWRF, which will help to account for the surface
fluxes in landfalling tropical cyclones and toNumber range CHAPTER
depict the hydrologic processes, including stream flow and flooding. At
NCEP, a new data assimilation system has been implemented for land
surfaces over the continental U.S. that insures self-consistent analyses
of temperature and moisture for the surface, soil, and canopy.

e\. An optimal forecast framework requirement
[]{#__RefHeading___Toc444699016 .anchor}

Given the requirement for a variety of forecast products derived from
such a complex, nonlinear modeling system with multiple, inter-dependent
components, questions of predictability arise. Operational forecast
centers currently issue deterministic and a few probabilistic products.
The optimal forecast framework for predicting damaging winds and heavy
rain likely will need a probabilistic component. Ensemble forecast
techniques are used operationally for periods ranging from one week out
to seasons. A common ensemble forecast approach for mid-latitude
synoptic weather systems is to assume the model is quite accurate and
the major source of uncertainty is in the initial conditions, so that
ensemble members are created by adding positive and negative
perturbations to the initial analysis. Such a "perfect model" assumption
has not been shown to apply for tropical cyclone intensity and rain
predictions; indeed, the existing models have significant biases that
could invalidate the common assumption in ensemble prediction that the
model errors are randomly distributed around a zero mean. For the
tropics, a few ensemble techniques were adopted in the past few years in
forecast operations for the short range (i.e., 0-72 h).

There is a theoretical limit of predictability for tropical cyclones due
to the chaotic nature of the atmosphere-ocean system. If a perfect model
of this system were to exist, all errors would be due only to poor
initial conditions due to lack of data and imperfect assimilation of the
data into the model. Current errors are larger than the theoretical
predictability limit and are a combination of the initial condition
errors and model errors. These two components are difficult to separate
(Palmer 2001, Toth and Vannitsem 2002). Only very preliminary research
into the predictability of track forecasts for tropical cyclones has
been performed (e.g., Aberson 2001, 2003; Leslie et al. 1998a). Little
is known of the inherent predictability of the intensity, structure, and
rainfall of tropical cyclones.

Another useful approach for ensemble forecasting is to perturb the model
physics by modifying physical parameterizations. Thus, a combination of
different model variations and perturbed initial conditions is used to
form the ensemble system. This approach is superior to perturbing only
the initial conditions. This approach could be particularly important
for tropical cyclone intensity prediction, considering the uncertainties
in the physics representations discussed above. Most current ensembles
are global applications. Research is needed on the effects of boundary
condition perturbations on limited area models.

3\. Science Plan[]{#__RefHeading___Toc444699017 .anchor}

Recent advances in computer capacity and modeling techniques now permit
the simulation of tropical cyclones in research models with nested grids
finer than 2 km. However, the Grand Challenge problem to simulate and
predict accurately hurricane winds and rain is far more complex than
simply running an existing hurricane model on a more powerful computer.
It will be necessary to understand the physical processes active at
these high resolutions and their impact on the development of an
enhanced hurricane simulation system through a synergy between
observationalists and modelers. This Initiative envisions and supports
the research necessary to understand and describe these processes and
their accurate representation in such an advanced simulation system and
their impact on the development of innovative subgrid-scale physical
parameterizations and improved numerical techniques.

Number range CHAPTERThere are compelling reasons why now is appropriate
time to launch an aggressive NOAA research effort to solve these
problems. The high-resolution models in the research community are
beginning to reproduce necessary characteristics of hurricane wind and
rain features. Research computing power will soon support
high-resolution models in real time, and a Development Testbed Center
(DTC) is planned as a platform for assembling and evaluating a complete
end-to-end hurricane modeling simulation system and components. The
current operational hurricane model is running at 15-20 km resolution,
and the operational community is not planning to run such models at 1-2
km until around 2013. The activities under this Initiative are expected
to provide the necessary understanding to allow operational centers to
accelerate their research and development. This research proposal is
intended to support the investigation of alternate techniques to solving
these difficult questions and to evaluate them in a controlled manner as
part of the hurricane simulation system running on the DTC.

Further, this system must include new methods of obtaining and
assimilating massive amounts of data. The research and forecasting
communities have arrived at a critical juncture. EMC is now ingesting
and evaluating much of the next-generation satellite data on a routine
basis. In addition, NOAA Doppler radars on aircraft provide data to
initialize these high-resolution models. Satellite communications and
high-speed Internet will provide the communications necessary to deliver
these Doppler data from aircraft and the WSR-88D. Future field programs
(e.g., CBLAST, CAMEX, and NOAA Hurricane Field Program) will enable the
research to advance our understanding of the inner core dynamics,
surface fluxes in high winds, and microphysics of rain. These and other
new observations and models must be integrated into forecast operations
in a consistent framework.

An integration of various components of the hurricane forecast problem
(e.g., improved physical understanding, observing, and modeling of the
processes that cause intensity change and flooding) provides the best
chance for success.

a\. Evaluating an enhanced simulation and forecast modeling
system[]{#__RefHeading___Toc444699018 .anchor}

The proposed hurricane research model system must include a fully
coupled atmosphere-wave-ocean model and a coupled full-physics land
surface model. Physical parameterizations need to be developed and
tested in the coupled modeling system at the proposed higher spatial and
temporal model resolutions. EMC is leading the development and
application of the HWRF modeling system. This Initiative will support
the advanced research necessary to accelerate this development through
examining and evaluating HWRF model system components at high
resolution, such as:

i.  microphysical parameterizations;

ii. three-dimensional turbulence scheme and subgrid-scale moist
    turbulence parameterization suitable for ≤2 km grid resolution;

iii. mismatches between the dynamics and numerics;

iv. wind-wave coupling in high wind conditions;

v.  effects of sea spray on surface heat, moisture, and momentum fluxes;

vi. improved atmospheric boundary layer parameterizations;

vii. improved representation of lower-tropospheric moisture (e.g.,
     associated with the Saharan air layer);

viii. improved simulations of ocean mixed-layer processes controlling
      SST and upper-ocean heat content;

ix. land surface processes (e.g., soil moisture, the diurnal cycle of
    ground temperature) and coupling to hydrological model;

x.  chemical processes and transports that can be used as tracers of
    dynamic processes in the core; and

xi. radiative interactions with microphysics and aerosols.

The EMC HWRF development is constrained by operational needs and time
constraints. The benefit of an enhanced HWRF model system running in a
research mode is the ability to evaluate and test model system
components in numerous configurations, initialized with post-processed
data sets without the operational constraints. The enhanced model will
be based on, and complement, the HWRF model infrastructure that is
currently under development at EMC. Evaluation and testing of the
enhanced model components with real data sets requires a very large
number of model integrations, and therefore high-speed computer
resources to accomplish the tasks. The very-high-resolution
atmosphere-wave-ocean and atmosphere-land modeling systems will be run
at the High Performance Computer System (Jet) at the NOAA FSL, or on
such other state-of-the-art computer systems as the Japanese Earth
System Simulator.

Very-high-resolution coupled hurricane-ocean-wave modeling will require
a nested grid configuration not only in the hurricane model but in the
ocean and wave models as well. The nested mesh capabilities are
presently being developed and applied for the WRF at EMC. Funding under
this Initiative will be used for evaluating and accelerating the
development of movable mesh technologies for the ocean and surface wave
components of the coupled system. In particular, movable nested mesh
algorithms will be evaluated for modeling the ocean circulation and
surface waves in those near-coastal areas with complex coastlines and
bathymetry. Very little is known at present about the dynamics of
atmosphere-ocean-wave interactions over continental shelves and shallow
coastal regions. It is one of the reasons hurricane forecasting in
near-coastal regions remains problematic. Explicit representation of the
ocean and surface waves in near-coastal areas, especially near such
strong ocean fronts as the Gulf Stream, is expected to be an important
requirement in the future coupled model that will be investigated under
this Initiative. The ocean model must be capable of resolving the
location and structure of the Gulf Stream, Loop Current, and Warm Ocean
Rings by assimilating radar altimeter and SST data.

b\. Probabilistic approaches versus deterministic
modeling[]{#__RefHeading___Toc444699019 .anchor}

The NOAA Strategic Plan is to provide probabilistic information so that
decision-makers have some measure of confidence in the forecasts.
Uncertainty due to initial condition and model errors can be addressed
with ensemble forecasting. Perturbations to initial and boundary
conditions attempt to mimic the effects of imperfect initial data and
assimilation, whereas perturbations to the model (parameterizations,
numerics, etc.) can provide information on the effects of model error on
the forecasts. Quantifying the expected effects can provide information
on the expected reliability of the forecasts and, therefore, help to
extend the ability of the models to provide useful forecasts and help to
provide probabilistic forecasts of various impacts (Richardson 2000, Zhu
et al. 2002).

The operational constraints of limited computer resources and the need
for forecast guidance timeliness will be the primary determinants of the
proposed ensemble system. If the ensemble is to be available in a timely
period, the prediction model must be degraded relative to the single
highest resolution, most sophisticated physics, and deterministic model
run at the forecast center. The more ensemble members to be included,
and the more model physics representation variations that are to be
included, the more compromises in horizontal and vertical resolution
must be made if the ensemble prediction is to be available in time to
still be useful to the forecaster. This Initiative will attempt to
determine the optimal configuration of resolution, physics, and number
of ensemble members.

Ensemble and probabilistic forecast guidance are important for another
reason. Even a perfect wind and rain forecast in a storm-relative
framework could be of no value if the forecast track is poor. Limits of
predictability, while not yet well defined, are likely \~150 km for 48
hour forecasts of the location of a hurricane's central features (e.g.,
Leslie et al. 1998). The most useful forecast information for winds and
rain is likely probabilistic.

Until 2002, no operational tropical cyclone forecasting ensemble (other
than the Beta Advection Model family) was available. With upgrades to
the resolution of the ten-member NCEP GFS ensemble, track forecasts are
now available on a regular basis, although some problems, such as
erroneous initial locations, remain with this system. Initial tests of
ensembles with the GFDL model identified challenges for adapting the
current ensemble perturbation generation techniques, which were created
for synoptic-scale mid-latitude systems, to the tropical cyclone
problem. Research into techniques to create ensembles directly from
hurricane models is only beginning, and it is an important first step in
utilizing this important technique to improve forecasts.

c\. Improved use of inner core
observations[]{#__RefHeading___Toc444699020 .anchor}

The development of new techniques for assimilating high-resolution data
sets is a fundamental activity required for advancing numerical
prediction of hurricane intensity and rain. New data sources are
critical to initializing the forecast system in two key domains: (1) the
large-scale environment and (2) the vortex core. By 2010, the GFS will
run as a global atmosphere/ocean coupled system with an advanced
four-dimensional data assimilation system (A4DDA). One of the most
significant challenges to be met by NCEP and other operational NWP
center over the next two decades is the assimilation of satellite data
(Surgi, personal communication).

The A4DDA system is planned for implementation at NCEP during 2006-10.
Research into the best technique for assimilation of high-density data
into highly nonlinear regions such as tropical cyclones is only
beginning (Surgi, personal communication). Preliminary work suggests
that four-dimensional variational techniques (4D-var) are problematic
even in highly simplified models (e.g., DeMaria and Jones 1993, Jones
and DeMaria 1999). Other advanced techniques such as ensemble-based
Kalman Filters and weak-constraint 4D-var techniques have shown some
promise in simple tropical cyclone models. In fact, synoptic-scale data
assimilation in tropical regions is also currently a very difficult
problem, and basic research in this area is required to allow for the
assimilation at higher resolutions and timescales.

Despite recent advances in instrumentation, satellite data must still be
augmented by conventional in-situ observations to provide the
high-resolution data in the inner core of the storm needed to improve
intensity and rain forecasts. Initialization of the second domain, the
vortex core, requires the development of a new mesoscale data
assimilation capability. In anticipation of running the high resolution
HWRF operationally, NCEP is developing such a capability to initialize
the hurricane core circulation using real-time, line-of-sight winds from
airborne and ground-based Doppler radars. This capability is being
developed in concert with NCEP's current 3D-var and will make use of
future advanced mesoscale variational data assimilation techniques being
developed at NCEP and by the research community.

This Initiative will explore using new inner-core atmospheric data
sources (e.g., from aircraft flight-level, global positioning system
(GPS) dropsonde, and Doppler radar) to initialize, evaluate, and
validate the HWRF model system, e.g., clouds, aerosols and land surface
processes. New techniques specifically designed for Airborne Expendable
Current Profiler (AXCP) and Airborne Expendable Bathythermograph (AXBT)
measurements and other in-situ data, combined with satellite Advanced
Very High Resolution Radiometer (AVHRR) and altimetry data, will be
explored. Particular attention will be paid to the representation of
oceanic mesoscale features, such as the depth of the thermocline,
fronts, and eddies ahead of the storm, through comparison with
observations from field experiments.

As with the modeling efforts, the research proposal intends to support
the investigation of alternate approaches and to evaluate the more
promising techniques as part of the hurricane simulations. This
Initiative will complement and enhance current operational model system
development plans at NCEP in the areas of quality control (QC) and data
assimilation. Quality control plays a central role in the success of any
data assimilation system and requires detailed, local information about
each data type. Developing QC standards and improving QC techniques will
be needed for observing systems, e.g., WSR-88D and airborne radar wind
and reflectivity observations; surface data from mesoscale networks; and
drifting buoy data.

Specific topics including EMC's priorities are:

i.  Improving the background error covariances and their evolution for
    the atmosphere, ocean, and land;

ii. Assessing the impact of atmosphere, ocean, and land model errors and
    biases;

iii. Identifying the key variables to be measured for NWP, including the
     requirements of accuracy and resolution in time and space and the
     tradeoffs between resolution and areal coverage;

iv. Development of strategies to extract maximum meteorological
    information from the data (e.g., adaptive thinning, "super-obbing,"
    recursive filters, etc.);

v.  Specifying the observation errors, especially in sensitive regions
    such as the inner core, and for surface observations in steep
    topography;

vi. Development of techniques for optimal use of dense spatially
    correlated observations;.

vii. Development of adaptive quality-control techniques;

viii. Development of assimilation techniques for available quantities,
      e.g., Doppler line-of-sight winds, air-sea fluxes, trace gases,
      aerosols; and

ix. Modeling of radiative interactions with microphysics and aerosols.

d\. Analysis, evaluation, and validation[]{#__RefHeading___Toc444699021
.anchor}

The data analysis task of estimating the continuous spatial and temporal
field from a set of discrete observations is closely linked with nearly
all phases in the design of a modeling system. High-quality analyses of
data, from both the models and observations, are valuable in studies
aimed at improving the understanding of the important physical processes
occurring in a given situation. Reliable analyses are also vital in
evaluating the performance of a model.

Many requirements must be considered in designing a data analysis scheme
for use in a system designed to improve forecasts of tropical cyclone
wind and rain. The analysis scheme must be able to cover spatial scales
ranging from thousands of kilometers to the sub-kilometer scale, and
temporal scales ranging from multi-day to sub-hourly periods. The
analysis must cover both the atmospheric and oceanic environments, and
extend from the lower stratosphere down to a depth in the ocean to
describe the ocean mixed layer and thermocline (\~100 m).

Another requirement is flexibility and adaptability. An analysis scheme
must be flexible so that it can accommodate a multitude of models and
observational platforms, and incorporate new model components and
platforms as they come online. Observational data will need to be of a
very high resolution. A great deal of observational information is
available now from such platforms as airborne Doppler radar measurements
of three-dimensional winds and reflectivity; GPS dropsonde measurements
of pressure, temperature, humidity, and winds; aircraft and satellite
microwave radiometer and scatterometer measurements of surface winds;
flight-level microphysical, trace gas, and aerosol measurements,
multi-level AXBT, AXCP, and Airborne Expendable Conductivity,
Temperature and Depth (AXCTD) measurements of ocean temperatures, heat
contents, and currents (along with their associated shears), and
satellite measurements of hydrometeor concentrations (e.g., TRMM
satellite), sea-surface height anomalies (e.g., JASON-1 missions), and
temperature and moisture profiles (e.g., Advanced Microwave Sounder Unit
\[AMSU\]). A scheme must be able to incorporate these platforms and
future platforms to produce the best analysis possible.

Additionally, a scheme must be adaptable to the needs at hand,
incorporating model output and observations. For example, it should be
able to attain a very high spatial and temporal resolution in the
hurricane inner-core region and be able to calculate trajectories, to
conduct case studies useful in process-study research. At the same time,
a scheme should be structured to allow for multiple-case calculations
for statistical approaches. Such an approach is valuable for diagnosing
physical relationships and conducting work designed to develop and
improve physical parameterization schemes in the modeling system.

The proposed system would address:

i.  integration of the numerous model and observational data sets into
    an archive for studying tropical cyclone intensity and rain. Such an
    archive will be useful, both for process-study research,
    parameterization development and improvement, and evaluation of the
    model system components. For example, a researcher could extract a
    specific case to analyze and compare with a simulation of that case,
    or compare with an idealized simulation of a system approximating
    the case being considered.

ii. developing a new analysis scheme to ensure that it has the
    flexibility to easily incorporate new data and the adaptability to
    allow for user-dependent approaches (i.e., case study vs.
    statistical comparisons). The development of such a scheme will be
    driven by the needs of the model evaluation and validation systems.
    The metrics used to evaluate the performance of the model depend on
    the needs of the researcher. Someone using a case-study approach can
    compare spatial distributions of relevant fields with the simulated
    fields to ensure a sufficient level of agreement, while someone
    testing parameterization schemes can compare statistics from the
    analyses of multiple cases and the simulations to assess the quality
    of the simulations.

iii. analyses and idealized modeling studies, as necessary to conduct
     basic research in fundamental topics for understanding tropical
     cyclone intensity and rain, e.g., eyewall mixing events through
     vortex Rossby-waves that can modify the inner-core vortex
     structure. Detailed analysis tools, such as trajectories and the
     accumulated fluxes along those trajectories, are necessary to
     adequately investigate the physical processes.

iv. analyses of data collected in current and future field programs,
    such as the surface flux contribution via sea spray, breaking waves
    from CBLAST, and the microphysical data from CAMEX-5 and NOAA's
    hurricane field program.

The development and maintenance of such an analysis system will require
continuous upkeep to allow the ability to incorporate new model
components and observational data sources. The bulk of the effort will
occur at the beginning of the 10-year period, during which time the
archive will be created, existing data sets will be incorporated into
the archive, and the new analysis scheme will be developed. Existing
schemes can be used to guide the development of this approach, or
entirely new ones can be developed. The resulting archive will be a
national and global resource for tropical cyclone forecasters,
researchers, emergency managers, and private industry to draw upon in
future applications.

e\. Observations and instrumentation
developments[]{#__RefHeading___Toc444699022 .anchor}

Funding under this element supports the collection of data sets
necessary for the development activities of other elements of the
Initiative. In recent years, our ability to observe tropical cyclones
has exceeded our ability to make effective operational use of the
observations. As a result, this Initiative will be able to leverage
existing instrumentation as well as developmental instrumentation for
which funding has already been identified. However, it is recognized
that activities under other elements of this Initiative may identify
additional data requirements not currently anticipated. It is presumed
that it will not be possible to collect the necessary measurements from
the inner core of a tropical cyclone solely using satellite-based
instruments and, therefore, instrumented aircraft will be the primary
observation platforms. The science plan recognizes the advantages
offered by using multiple types of aircraft and the opportunities for
data acquisition offered by operational reconnaissance aircraft. This
Initiative contains funds for enhancements to the operational
reconnaissance fleet as well as to the NOAA research aircraft.

Successful initialization of the next-generation hurricane model will
require concurrent observations of the atmosphere and ocean, on scales
ranging from the synoptic to the convective.

i.  Atmospheric measurements: Synoptic-scale observations in the cyclone
    environment will continue to be obtained remotely by operational
    satellites and will be supplemented in this Initiative by GPS
    dropwindsondes (Hock and Franklin, 1999) released from the NOAA
    Gulfstream-IV (G-IV) and WP-3D, and Air Force Reserve C-130J
    aircraft. Doppler radars on the WP-3Ds and proposed for the G-IV
    will be used to obtain three-dimensional wind fields in regions with
    scatterers. Wind measurements in clear air will be made using a
    proposed scanning Doppler lidar. Wind measurements in the
    atmospheric boundary layer (Powell et al., 2003) will be obtained
    using dropwindsondes and a "Dopplerized" scatterometer referred to
    as the Imaging Wind and Rain Atmospheric Profiler (IWRAP). Surface
    winds over water will be remotely sensed using the Stepped-Frequency
    Microwave Radiometer (SFMR) from the WP-3D aircraft (Uhlhorn and
    Black 2003) and the IWRAP system operated in scatterometer mode at
    the dual C and Ku-band frequencies.

ii. Oceanic and interface instrumentation: Observations of upper-ocean
    thermal and momentum structure will be made using air-deployable
    instruments (e.g. AXBTs, AXCPs, and AXCTDs \[Shay et al. 1998\]) to
    map background and hurricane-induced oceanic circulation (current
    shears) and heat content (OHC) variability in an Eulerian sense.
    AXBTs and Lagrangian floats deployed from the Air Force Reserve
    C-130J would provide detailed OHC and upper ocean turbulence
    measurements (D'Asaro 2003). NASA Scanning Radar Altimeter (SRA) on
    the WP-3D would resolve the low-frequency surface waves, i.e., the
    ocean swell (e.g., Wright et al. 2001). The instrumentation could
    include the radome gust probe including a Lyman-α hygrometer and a
    water vapor analyzer to determine bulk exchange coefficients for
    heat, moisture, and momentum in high wind speed and ocean waves. The
    new Best Atmospheric Turbulence (BAT) probe together with the
    Infrared Gas Analyzer (IRGA), currently in the development stage for
    the Office of Naval Research (ONR) CBLAST program, could also
    measure turbulent fluxes.

iii. Microphysics, trace gas, and aerosol measurements: Microphysics
     observations from the NOAA WP-3D aircraft are essential to improve
     the representation of the rain drop-size distribution for
     development and evaluation of microphysics parameterization for the
     enhanced model system. Similar observations of the ice microphysics
     characteristics (e.g., species and number density), essential for
     the parameterization development, must be acquired in collaboration
     with the NASA CAMEX efforts. Trace gas and aerosol distributions in
     hurricanes from NOAA WP-3D aircraft will be employed to improve
     understanding of hurricane structure and dynamics, and to assess
     effects of the massive redistribution by hurricanes of boundary
     layer gases and aerosols into the upper troposphere and lower
     stratosphere. Trace gases in the marine troposphere and lower
     stratosphere are massively disturbed by hurricanes. Gas exchange
     between the ocean surface and the boundary layer is significantly
     enhanced by the strong winds and low barometric pressure of a
     hurricane. These gases are transported vertically as high as 15 km
     and redistributed over a large area, or mixed with stratospheric
     air in the region above the eye. Aerosols act as tracers for
     dynamic processes in the absence of clouds and can be used to
     delineate these processes.

iv. NOAA aircraft upgrade: While the NOAA WP-3D aircraft contain much of
    the instrumentation needed to support these observational
    requirements, separate funding (\$13M) was proposed to upgrade
    instrumentation on the NOAA G-IV. This instrumentation is likely to
    include modified nose radar for composite reflectivity and velocity
    measurements, a scanning Doppler lidar for wind measurements in
    clear air, a microwave temperature profiler, and mini-AXBTs for
    ocean temperature profiles. It is not anticipated that the G-IV
    upgrade will provide moisture or cloud microphysics observations;
    therefore, this Initiative includes development of a Differential
    Absorption Lidar (DIAL) system for the NOAA WP-3D aircraft to
    provide vertical moisture profiles and upgrades to the WP-3D
    microphysical probes.

While many key components of an observing system are in place, it is
unclear how best to use the observations in evaluating and validating
the proposed high-resolution model system. New observing platforms
require calibration and validation against tested platforms. While
calibration/validation programs are typically a part of the development
of remote and in-situ sensing platforms, it may not always be possible
to include tropical cyclone cases in such programs. For example, surface
wind measurement systems usually fail during hurricane-force winds. Only
after the characteristics of the new platforms are well understood can
the new observations be used effectively to answer questions about
specific physical processes and be assimilated effectively into
numerical models.

Doppler radars on the WP-3Ds currently provide three-dimensional wind
fields, but it remains unclear as to the level of airborne processing
required before these data are assimilated. It is also unclear whether
the sampling interval of these wind fields is adequate to support the
high-resolution model system initialization requirements. The
instrumentation plan includes funding to support enhanced Doppler radar
analysis techniques utilizing both the tail Doppler radar and the IWRAP
systems.

Oceanic/interface observations will be used to generate
three-dimensional maps of ocean currents, temperatures, salinities,
isotherm depths, shears, and oceanic heat content (Shay et al., 2000),
and to relate to fields of wind, shear, humidity, and temperature
(equivalent potential temperature) for assimilation and comparison to
model simulations to evaluate model physics. Surface wave spectra
(significant wave height), surface winds, and air-sea fluxes will be
used in wave modeling studies and empirical studies to examine the
enthalpy fluxes and the bulk coefficients. Process-oriented studies will
involve using simple models (e.g., effects of surface waves on the ocean
mixed layer, wave-current interactions, wave effects on air-sea fluxes,
and impact of secondary boundary layer flows on surface fluxes).

Microphysics observations are essential to define the natural
variability of hydrometeor characteristics in tropical cyclones. These
data sets will be used to define ice and raindrop number concentrations,
drop-size distributions, liquid and ice water contents, and ice crystal
habits in different parts of the storm. These characteristics will be
used for improving rain estimates from in-situ and remote sensors, and
for evaluation and development of microphysics parameterization schemes.
Trace gas and aerosol measurements will be used to provide
concentrations of the different gases and aerosol types. The horizontal
and vertical variation of these trace gas and aerosol concentrations are
critical to improving our understanding of hurricane structure and
dynamics, and in assessing effects of massive redistribution by
hurricanes of boundary layer gases into the upper troposphere and lower
stratosphere.

f\. Transition to operations[]{#__RefHeading___Toc444699023 .anchor}

As noted, the NOAA Research Council defined short-term research,
long-term research, and research-to-operations goals. This Initiative
focuses on long-term research to provide underlying knowledge and
techniques with the potential to be incorporated by operational centers
in future generations of data acquisition, assimilation, and numerical
forecast systems beyond four to five years. Unlike research and
development tasks of operational centers, which focus primarily on
systems slated for operations in the next one to four years, it is not
the intent of long-term research to investigate any one approach or
solution. Rather, the purpose of long-term research is to investigate
several lines of attack to broaden understanding and create
alternatives. These alternatives can then be evaluated under controlled
conditions, using controlled data sets, to determine which of several
approaches perform best and demonstrate the greatest potential to
improve operational systems.

Promising new knowledge or advanced techniques may require additional
applied research and development to build in necessary rigor or to adapt
the approach to operations even though such techniques have been
evaluated on the DTC. Interactions between the research and the
operations development community should specify the process for moving
promising techniques into operations. Basic and advanced research leads
to applied research and development, which then makes use of testbeds to
ensure the observations, analyses, and numerical techniques are ready
for operations. The intent is to shorten the amount of time it takes for
the long-term research knowledge to impact operations positively.

Some transition activities could be evaluated at the JHT or other future
operational testbed facilities. The purpose of JHT is to identify mature
research results that have the promise to improve operational tropical
cyclone forecasting,, then to facilitate the transition of that research
into an operational product. That transition could be to the National
Hurricane Center (or other U.S. warning center), in which case the
testing and evaluation should lead to a real-time operational guidance
product that is timely and forecaster-friendly so that an improved
forecast will be produced. The transition could also be to improve the
numerical model guidance for tropical cyclone forecasting, in which case
the coding, testing, and evaluation will be at the DTC. This Initiative
will be executed in close collaboration with these facilities as each
research component matures so that a rapid and smooth transition to
operations is ensured.

g\. Program management[]{#__RefHeading___Toc444699024 .anchor}

This program will be administered by the NOAA OAR Office of Weather and
Air Quality. NOAA OAR will be advised by a scientific and technical
advisory committee, chaired by the OAR Atlantic Oceanographic and
Meteorological Laboratory Hurricane Research Division director, with
representation from the USWRP, NWS to include the NCEP EMC and Tropical
Prediction Center/National Hurricane Center, university community, other
OAR laboratories (e.g. FSL and GFDL) and other government laboratories.
The committee will provide overall leadership and management by defining
annual programs and overseeing the awards process and extramural
research. The committee will also perform scientific assessments of
resulting research and serve as a knowledgeable source for technical
information. The committee will coordinate with other advisory groups,
e.g., DTC, WRF, JHT, JCSDA, and THORPEX.

h\. Schedule and interim milestones[]{#__RefHeading___Toc444699025
.anchor}

2005

-   Begin evaluating and examining vortex-following, multi-nested grids
    HWRF enhancement with innermost mesh at ≤2 km resolution (enhanced
    HWRF) at a computational center.

-   Assist EMC in constructing background error covariance functions for
    analyzing inner-core circulation by variational methods.

-   Begin compilation of datasets for creation of an archive from
    existing and planned datasets.

-   Begin development of flexible, adaptable data analysis system.

-   Conduct field program on moisture impacts on intensity (AMMA,
    CAMEX).

-   Begin developing techniques to better utilize inner-core data (e.g.,
    Doppler radar, AXCP and AXBT) to provide a balanced inner-core
    vortex and underlying ocean circulation.

-   Begin to explore and examine new or improved parameterizations of
    turbulence and microphysics for enhanced HWRF.

2006

-   Examine and evaluate ocean and surface wave model components for
    enhanced coupled HWRF. Evaluation must include selected operational
    model components.

-   Further examine and evaluate movable, nested grids for both ocean
    and surface wave models in enhanced HWRF, as necessary.

-   Investigate methods to better use observations in the initialization
    of the land surface model, ocean wave model, and ocean circulation
    model.

-   Complete development of archive, continuously add to archive as new
    datasets are collected; identify benchmark storms for evaluation and
    validation.

-   Install DIAL, upgraded microphysics systems, and operational IWRAP
    systems on both WP-3D aircraft; install SFMR and AXBT systems on
    four Air Force Reserve C-130J's.

2007

-   Examine and evaluate new wind-wave and wave-current coupling
    parameterizations for enhanced HWRF, including the effects of sea
    spray.

-   Examine and evaluate each model component with observations from
    archive and field experiment data.

2008

-   Begin diagnostic tests of enhanced model, running comparisons with
    operational HWRF on storms in research database, with emphasis on
    those sampled by focused observational programs. Tests will include
    comparisons to the operational HWRF using multiple horizontal
    resolutions (e.g., 1, 2, 5, 10 and 15 km) for the atmospheric model
    and 1/6, 1/12, and 1/24 degree for the ocean and surface wave
    models.

-   Complete creation of analysis system with flexibility to include new
    platforms.

-   Streamline the data analysis and make it available in near
    real-time.

-   Conduct enhanced field program on core sampling (winds,
    microphysics, trace gases, and aerosol) and ocean effects.

-   Complete Doppler radar data initialization technique evaluation.

2011

-   Conduct enhanced field program.

All years

-   Coordinate transition of successful components to operational
    systems through potential companion NOAA hurricane short-term
    initiative and testbeds .

-   Hold annual workshop.

-   Prepare annual science report.

-   Prepare annual administrative report.

-   Distribute announcements of opportunities, as appropriate.

i\. Deliverables[]{#__RefHeading___Toc444699026 .anchor}

Major deliverables include components of an enhanced HWRF model system
running with multiple movable meshes at the highest resolution of ≤2 km
as tools for future operational HWRF development. These components will
include an atmosphere and ocean model compatible with the operational
system, with appropriate microphysics and interface processes, including
waves, spray, etc., for such high-wind regimes. Along with the model
system will be an archive containing all necessary quality-controlled
observations from storms sampled during focused experiment programs to
initialize, evaluate, and validate the enhanced HWRF simulations. Any
new strategies for the use of the enhanced observations will be tested
and evaluated with the enhanced HWRF.

j\. Relevance of work and synergistic
activities[]{#__RefHeading___Toc444699027 .anchor}

This Initiative would complement and strongly benefit from ongoing and
planned USWRP HL sponsored research, technology transfer (JHT), and
planned operational forecast development activities through broadened
participation of the research community in the WRF system development
and operational development at EMC. It will be coordinated with the EMC
HWRF development efforts to facilitate transfer of improvements to
operations. This research will be accomplished by augmenting current
projections for NOAA research and drawing in non-NOAA expertise from
other Federal agencies, the university community, international
researchers (e.g., Australia, Canada, France and Taiwan), and the
private sector. It will also benefit from, and complement, efforts made
through the USWRP HL focus, such as high-resolution modeling,
observational efforts to sample moisture and microphysics via the
ongoing NASA CAMEX series, the ONR CBLAST program, and the proposed
THORPEX activities that will be addressing related issues for
mid-latitude systems on larger space and time scales.

While an HL implementation plan is in place (Elsberry 2001), a science
advisory team will be formed to update the plan by 2005. The development
of the WRF model as the next generation hurricane model was the topic of
a second USWRP Workshop on Hurricanes and Tropical Meteorology in San
Diego, CA on 29-30 May 2002 and the reader is referred to that workshop
report for a detailed description (Elsberry 2002). At the San Diego
Workshop, the design characteristics of an operational model were
discussed. This was followed by a workshop that presented a
comprehensive plan by NCEP/EMC on the development of the operational
HWRF system at the National Science Foundation in Arlington, VA (Surgi
and Evans 2003).

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C. Proposal Budget[]{#__RefHeading___Toc444699029 .anchor}

1\. Cumulative budget[]{#__RefHeading___Toc444699030 .anchor}

\$7.56M/year, where \$3.86M/year is for additional manpower beyond base,
\$2.4M/year for costs of acquiring new observations and field
experiments, \$0.3M/year for travel, and an estimate of \$1.0M/year for
computer costs. This assumes 1 man year=\$200k for salary, overhead, and
infrastructural needs (fully burdened).

2\. Annual budget[]{#__RefHeading___Toc444699031 .anchor}

<table>
<colgroup>
<col style="width: 13%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 9%" />
</colgroup>
<tbody>
<tr class="odd">
<td></td>
<td>2005</td>
<td>2006</td>
<td>2007</td>
<td><blockquote>
<p>2008</p>
</blockquote></td>
<td>2009</td>
<td>2010</td>
<td>2011</td>
<td>2012</td>
<td>2013</td>
<td>2014</td>
<td>Totals</td>
</tr>
<tr class="even">
<td>Enhanced HWRF evaluation total ($M)</td>
<td>2.1</td>
<td>2.5</td>
<td>2.5</td>
<td><blockquote>
<p>2.5</p>
</blockquote></td>
<td>3.0</td>
<td>3.0</td>
<td>3.0</td>
<td>3.0</td>
<td>3.0</td>
<td>3.0</td>
<td>27.6</td>
</tr>
<tr class="odd">
<td>Improved use of inner core observations total ($M)</td>
<td>1.0</td>
<td>1.0</td>
<td>1.5</td>
<td><blockquote>
<p>1.5</p>
</blockquote></td>
<td>1.5</td>
<td>1.5</td>
<td>1.5</td>
<td>1.5</td>
<td>1.5</td>
<td>1.5</td>
<td>14.0</td>
</tr>
<tr class="even">
<td>Analysis and archival of data total ($M)</td>
<td>1.0</td>
<td>1.0</td>
<td>1.0</td>
<td><blockquote>
<p>1.0</p>
</blockquote></td>
<td>1.0</td>
<td>1.0</td>
<td>1.0</td>
<td>1.0</td>
<td>1.0</td>
<td>1.0</td>
<td>10.0</td>
</tr>
<tr class="odd">
<td>Observation and instrument development total ($M)</td>
<td>3.0</td>
<td>6.0</td>
<td>1.5</td>
<td><blockquote>
<p>3.0</p>
</blockquote></td>
<td>1.5</td>
<td>1.5</td>
<td>3.0</td>
<td>1.5</td>
<td>1.5</td>
<td>1.5</td>
<td>24.0</td>
</tr>
<tr class="even">
<td>Total ($M)</td>
<td>7.1</td>
<td>10.5</td>
<td>6.5</td>
<td><blockquote>
<p>8.0</p>
</blockquote></td>
<td>7.0</td>
<td>7.0</td>
<td>8.5</td>
<td>7.0</td>
<td>7.0</td>
<td>7.0</td>
<td>75.6</td>
</tr>
</tbody>
</table>

3\. Justification[]{#__RefHeading___Toc444699032 .anchor}

Supporting the proposed science plan requires \$2.8M/year on average for
enhanced HWRF evaluation, where \$1M/year is for computational costs.
The remainder covers manpower activities (\~12-13 man years including
principal investigators, research associates, post-docs, and students).
The improved use of inner core data effort averages \$1.4M/year in
manpower activities (\~6-7 man years). Analysis, evaluation and
validation effort manpower needs are estimated to average \$1M per year,
with about 10% for computing needs activities (\~4 man years).
Observation and instrumentation development costs average \$2.6M per
year. This estimate is about half for manpower (\~6-7 man years) and
half for acquiring new observational capabilities and data collection.
In all cases, resources for manpower are to be roughly evenly split
between NOAA and non-NOAA personnel (university and other private
institutes). Manpower for administrative support is expected to be 1
person per year at AOML.

The observation costs are \$1.5M per year, except for three major field
experiment years in 2005, 2008, and 2011 when the costs double to \$3M
per year. The \$1.5M is broken down roughly into the cost for 75 flight
hours with full overhead on each of the NOAA WP-3D and G-IV aircraft,
expendables for the NOAA and Air Force Reserve aircraft (300 GPS sondes
and 200 AXBTs), travel and overtime for scientists to participate in
flights, and telecommunication charges for the satellite communications.
In the major field program years, the costs are increased to accommodate
twice the flight hours, GPS sondes, AXBTs, travel, overtime, and
telecommunications charges, plus an additional \$750K per year for
AXCPs, AXCTDs, and Lagrangian floats to map the OML structure.

The additional (\$4.5M) observation and instrument costs in 2006 are for
the development and installation of a DIAL system on one WP-3D,
procurement and installation of upgrades to both WP-3D microphysical
probes, procurement and installations of IWRAP systems on both WP-3D
aircraft, and procurement and installation of new SFMR and AXBT systems
for both WP-3D aircraft and four Air Force Reserve C-130J's.

Other costs include those for non-modeling computing (e.g., servers and
disk space to support the data collection and the observational and
model data archive and analysis tools estimated at \$1M/year the first
three years and about \$500K/year the remaining years.), and non-field
experiment related telecommunications and travel (e.g., meetings,
workshops, etc. estimated at \$15K/year).

D. Current and Pending Support[]{#__RefHeading___Toc444699033 .anchor}

Base is Hurricane Research Division \~\$1.5M; GFDL \$0.4M; EMC \$0.4M

E. Facilities, Equipment, and Other
Resources[]{#__RefHeading___Toc444699034 .anchor}

NOAA and Air Force Reserve (AFRES) Aircraft

-   WP-3D hours

-   G-IV hours

-   AFRES C-130J hours

-   telecommunications

## Expendables

-   WP-3D GPS sondes

-   WP-3D Ocean probes

-   G-IV GPS sondes

-   C-130 GPS sondes

-   Ocean Floats

Aircraft Instrumentation upgrades

-   WP-3D upgrades

-   C-130 upgrades

Computational

-   Central Processor Unit hours

-   Disk space

-   Telecommunications

F. Acknowledgements[]{#__RefHeading___Toc444699036 .anchor}: The
drafting of this Initiative was a group effort, which included inputs
from:

  --------------------------- -------------------------------------------
  Frank Marks                 Hurricane Research Division (HRD)

  Ed Rappaport                NHC

  Naomi Surgi                 EMC

  Shuyi Chen                  University of Miami/Rosenstiel School for
                              Marine and Atmospheric Sciences (UM/RSMAS)

  Russ Elsberry               U. S. Naval Postgraduate School

  James Franklin              NHC

  Nick Shay                   UM/RSMAS

  Sim Aberson                 HRD

  Rob Rogers                  HRD

  Morris Bender               GFDL

  Isaac Ginis                 University of Rhode Island

  Mike Montgomery             Colorado State University

  Bill Frank                  Pennsylvania State University (PSU)

  Jenni Evans                 PSU

  Chi-Sann Liou               Naval Research Laboratory, Monterey

  Jin-Leun Lee                FSL

  Russel Morison              University of New South Wales

  Richard Pasch               NHC

  Peter Dodge                 HRD

  Kevin McCarthy              HPC
  --------------------------- -------------------------------------------

The team would also like to thank Ward Seguin and John Gaynor of the
USWRP Interagency Program Office for their invaluable assistance.

Appendix[]{#__RefHeading___Toc444699037 .anchor}Number range CHAPTER

[Benefit]{.underline}

Achieving the Initiative's goals will save up to \$19 million in
preparation costs and decrease the "false alarm" rate by about 20% for
each Atlantic hurricane striking the United States. This will occur
through projected improvement in intensity forecasts combined with
model-based guidance on forecast confidence and uncertainty.

[Background Information]{.underline}

 Hurricane preparations cost about \$640K-\$1 million per mile of
coastline.

 Preparation decisions usually begin 24-48 hours ahead of the
hurricane.

 Average 24-48 hour intensity (wind speed) forecast errors are 10-15
kt.

 15 kt corresponds to one category on the Saffir-Simpson Hurricane
Scale.

 Based on the average forecast error, emergency managers follow NWS
recommendations to prepare communities for a hurricane one category
stronger than the category NWS forecasts.

 If intensity forecasts were more accurate (off by less than one
category; goal of this Initiative is about 1/2 category) and users had
confidence in the forecast (and a means to assess forecast confidence),
communities could prepare for the specific category of hurricane
forecast by the NWS. Fewer preparations would be required and fewer
people would need to prepare, thereby decreasing the false alarm rate.
Savings realized.

[The Calculation]{.underline}

 Use \$640K per mile of coastline as the cost of preparation (likely
conservative amount).

 The United States east and Gulf coasts have about 3560 miles of
coastline.

 About 50 million people live in coastal counties.

From the above three bullets, the cost of preparation in coastal
counties is estimated at \$42 per person.

 The number of evacuees, stratified by category of hurricane, was
obtained from coastal counties in southern Florida (Sarasota, Charlotte,
Lee, Collier, Monroe, Miami-Dade and Broward). These counties extend
about 375 statute miles, or about the average length of a hurricane
warning.

 Assume preparations occur in the hurricane warning area (see Figure
A-1 for Collier County).

 The difference in the number of evacuees between categories 3 and 2
for south Florida is 406,627.

-Used half of combined categories 2+3 total exceeding category 1 for
Miami-Dade County.

 Assume preparations at the average cost per person (\$42) apply to the
extra evacuees. Total extra cost is \$17.078 million for south Florida.

• Scaling south Florida cost to average population density of U.S. east
and gulf coastline gives \$19 million for about 460,000 people per
event.

-Used U.S. east and gulf county coastal population of 50 million people
over 3560 miles.

-Used south Florida county coastal population of 4.5 million people over
375 miles.

-Gives scale factor is 1.13.

 \$19 million for the extra evacuees is an estimate of the preparation
costs to be saved for forecasts where the intensity forecast does not
have to be incremented by one category. This is the potential savings
for each storm provided by the advances intended by this Initiative.

[Cost Recovery]{.underline}

 Initiative cost recovered 3-9 years after operational implementation
of a fully successful research program. Additional savings would follow.

> -Used program cost of \$75 million and climatological average of 1.7
> hurricane hits each year.
>
> \- Assumes 1/2 category accuracy sufficient to allow preparations only
> for the category forecast in every case (3 years) to 1/3 of cases or
> 1/3 of counties in all cases (9 years).
>
> Provided by E. Rappaport
>
> ![](media/image5.jpeg){width="6.235416666666667in" height="8.23125in"}
>
> Figure A-1. Hurricane evacuation zones for Collier County, Florida.
> Available in local telephone books in the State of Florida. Colors
> from red to cyan denote evacuation zones for increasing hurricane
> strength.

[^1]: Term implying a complex problem requiring an effort of national
    scope (i.e., beyond one agency); cf, Tristram 2003