**Second Annual Report for the Land Information System**

**Submitted under Task Agreement GSFC-CT-2**

**Cooperative Agreement Notice (CAN) CAN-00OES-01**

**Increasing Interoperability and Performance of Grand Challenge
Applications in the Earth, Space, Life, and Microgravity Sciences**

Period Covered: September 1, 2002-August 31, 2003

Version 1.0

# Table of Contents

[**Table of Contents ii**](#table-of-contents)

[List of Figures iii](#list-of-figures)

[List of Tables iii](#list-of-tables)

[Acronyms and Terms iv](#acronyms-and-terms)

[1 Objective 1](#objective)

[1.1 Project goals 1](#project-goals)

[1.2 Land Surface Modeling Background
1](#land-surface-modeling-background)

[2 Approach 2](#approach)

[2.1 FY03 Milestones 2](#fy03-milestones)

[2.2 Out-year Milestones 2](#out-year-milestones)

[3 Scientific Accomplishments 3](#scientific-accomplishments)

[4 Technology Accomplishments 3](#technology-accomplishments)

[4.1 Design Policy for Interoperability and Community Delivery
3](#design-policy-for-interoperability-and-community-delivery)

[4.2 First Code Improvement 4](#first-code-improvement)

[4.3 Interoperability Prototype 5](#interoperability-prototype)

[5 Status/Plans 6](#statusplans)

[5.1 Interfacing with the developing ESMF
6](#interfacing-with-the-developing-esmf)

[5.2 User Interface Development 7](#user-interface-development)

[5.3 Customer Delivery to NOAA/NCEP 8](#customer-delivery-to-noaancep)

[5.5 FY04 Plans 9](#fy04-plans)

[6 Points of Contact 9](#points-of-contact)

[7 List of Publications 9](#list-of-publications)

[8 List of Conference Presentations
10](#list-of-conference-presentations)

[9 List of Media References 10](#list-of-media-references)

[10 List of Patents Filed 10](#list-of-patents-filed)

[11 List of Students/Post Docs Trained
10](#list-of-studentspost-docs-trained)

[11.1 Students Trained 10](#students-trained)

[11.2 Post Docs Trained 10](#post-docs-trained)

[12 References 10](#references)

#  

# List of Figures

[Figure 1. LIS timing results for Milestone F on Lomax at 5km.
4](#__RefHeading___Toc52961070)

[Figure 2. Latent heat flux (Qle) from the VIC land surface model in LIS
v2.0. Spatial resolution is 1/4 degree. 5](#__RefHeading___Toc52961071)

[Figure 3. Same as Figure 2., except spatial resolution is 5 km. Note
features resolved by the increased resolution, including urban areas
(e.g., Baltimore-Washington, Atlanta, Houston), as well as the
coastlines. 6](#__RefHeading___Toc52961072)

[Figure 4. The Land Information System Level 1 User Interface.
7](#__RefHeading___Toc52961073)

[Figure 5. Prototype LIS level 3 user interface.
8](#__RefHeading___Toc52961074)

# List of Tables

[Table 1. Reduction in memory and execution time on a single processor
for LIS relative to LDAS for one day, 1/4 degree global run with the
Noah land surface model. 4](#__RefHeading___Toc52961077)

# Acronyms and Terms

**ALMA:** Assistance for Land-surface Modeling Activities

**API:** Application Programming Interface

**CGI:** Common Gateway Interface

**CLM:** Community Land Model

**DODS**: Distributed Ocean Data System

**EMC:** Environmental Modeling Center

**ESMF:** Earth System Modeling Framework

**GFS:** Global Forecast System

**GrADS:** Grid Analysis and Display System

**LDAS:** Land Data Assimilation System

**LIS:** Land Information System

**MRTG:** Multi Router Traffic Grapher

**NCEP:** National Centers for Environmental Prediction

**NFS:** Network File System

**NOAH:** National Centers for Environmental Prediction, Oregon State
University, United States Air Force, and Office of Hydrology Land
Surface Model

**NOAA:** National Oceanic and Atmospheric Administration

**PXE:** Preboot Execution Environment

**RAID:** Redundant Array of Inexpensive Disks

SNMP: Simple Network Management Protocol

**VIC:** Variable Infiltration Capacity Land Surface Model

# 1 Objective

This Annual Report summarizes the activities and accomplishments of the
Land Information System (LIS) project during FY03. The overarching
objective of the LIS project is to build a high-resolution,
high-performance land surface modeling and data assimilation system to
support a wide range of land surface research activities and
applications.

This document has been prepared in accordance with the requirements of
the Task Agreement GSFC-CT-2 under Cooperative Agreement Notice
CAN-00-OES-01 Increasing Interoperability and Performance of Grand
Challenge Applications in the Earth, Space, Life, and Microgravity
Sciences, funded by NASA's ESTO Computational Technologies (formerly
High Performance Computing and Communications) Project.

## 1.1 Project goals

As stated in the proposal and approved software engineering documents,
the goals of LIS include:

-   Realistic land surface modeling. LIS will simulate the global land
    surface variables using various land surface models, driven by
    atmospheric "forcing data" (e.g., precipitation, radiation, wind
    speed, temperature, humidity) from various sources.

-   High performance computing. LIS will perform high-performance,
    parallel computing for near real-time, high-resolution land surface
    modeling research and operations.

-   Efficient data management. The high-resolution land surface
    simulation will produce a huge data throughput, and LIS will
    retrieve, store, interpolate, re-project, sub-set, and backup the
    input and output data efficiently.

-   Usability. LIS will provide intuitive web-based interfaces to users
    with varying levels of access to LIS data and system resources, and
    enforce user security policies.

-   Interoperable and portable computing. LIS will incorporate the ALMA
    (Assistance for Land surface Modeling Activities) and ESMF (Earth
    System Modeling Framework) standards to facilitate inter-operation
    with other Earth system models. In order to demonstrate portability
    of LIS, the land surface modeling component will be implemented on a
    custom-designed Linux cluster and an SGI Origin 3000.

## 1.2 Land Surface Modeling Background

In general, land surface modeling seeks to predict the terrestrial
water, energy and biogeochemical processes by solving the governing
equations of the soil-vegetation-snowpack medium. Land surface data
assimilation seeks to synthesize data and land surface models to improve
our ability to predict and understand these processes. The ability to
predict terrestrial water, energy and biogeochemical processes is
critical for applications in weather and climate prediction,
agricultural forecasting, water resources management, hazard mitigation
and mobility assessment.

In order to predict water, energy and biogeochemical processes using
(typically 1-D vertical) partial differential equations, land surface
models require three types of inputs: 1) initial conditions, which
describe the initial state of land surface; 2) boundary conditions,
which describe both the upper (atmospheric) fluxes or states---also
known as \"forcings\"---and the lower (soil) fluxes or states; and 3)
parameters, which are a function of soil, vegetation, topography, etc.,
and are used to solve the governing equations.

The LIS now includes various components that facilitate global land
surface modeling within a data assimilation system framework. The main
software components of the system are:

-   Land Data Assimilation System (LDAS): LDAS is a software system that
    integrates land surface models in a data assimilation framework.

-   Land surface Models: LIS includes 3 different land surface models,
    namely, CLM, NOAH, and VIC.

These components are explained in detail in the LIS Software Design
Document.

# 2 Approach

The overall approach for the LIS project involves parallel efforts
throughout the three-year project directed towards the performance and
interoperability goals of the original CAN, while adopting standard
software engineering methodologies to ensure that the products are
portable, reusable, extensible and maintainable.

Activities during FY03 have been focused on progress toward the
interoperability and first code improvement milestones. An annual "all
investigator" meeting, including interoperability and user interface
design reviews, was held on January 21, 2003, in addition to continuing
weekly local team meetings and monthly teleconferences. We also recently
became formal "ESMF partners", and have actively participated in ESMF
meetings and reviews. The FY03 milestones and out-year milestones are
given in the table below, and are described in more detail on the LIS
web site (http://lis.gsfc.nasa.gov).

## 2.1 FY03 Milestones

> H\) Design policy for Interoperability and 28-FEB-2003
>
> Community Delivery
>
> F\) First Code Improvement 30-MAR-2003
>
> I\) Interoperability Prototype 30-JUL-2003

C\) FY03 Annual Report 30-AUG-2003

## 2.2 Out-year Milestones

G)  Second Code Improvement 28-FEB-2004

```{=html}
<!-- -->
```
J)  Full Interoperability demonstrated 30-JUL-2004

K)  Customer delivery Accomplished 30-AUG-2004

> K\) Present LIS to Review Board 30-AUG-2004
>
> D\) Final Report Delivered 28-FEB-2005

# 3 Scientific Accomplishments

The Land Information System is based largely on the Land Data
Assimilation System (LDAS;
[http://ldas.gsfc.nasa.gov](http://ldas.gsfc.nasa.gov/)), and is the
product of a 5-year effort towards the goal of modeling land surface
states and fluxes, while relying as much as possible on
observation-based parameter and forcing fields in order to avoid biases
that are known to exist in forcing fields produced by atmospheric
models. A recently published article describes the science of LDAS in
detail (Rodell et al., 2003).

# 4 Technology Accomplishments

As stated above, the second year of the LIS project has focused on
progress toward the FY03 interoperability and code improvement
milestones, and the technology accomplishments associated with these
milestones are described below.

## 4.1 Design Policy for Interoperability and Community Delivery

As stated above, the LIS interoperability design was reviewed by members
of the LIS and LDAS teams, as well as collaborators from Princeton,
COLA, and NCEP, at the LIS annual meeting held January 21, 2003. The LIS
interoperability design was approved by CT in March 2003. As part of the
Milestone H submission, the following documents were submitted and
approved:

-   Software Design Document, including detailed "sub-documents":

    -   User Interface Design Document

    -   Interface Design for Interoperability

    -   Data Management Document

-   Software Requirements Specification

-   Software Traceability Matrix

As described in detail in the above documents, LIS defines two different
types of interoperability: internal and external. ***Internal***
interoperability mainly deals with the aspects of making components
within LIS interoperable, and ***external*** interoperability deals with
the interaction of LIS with other related scientific community
applications and standards. Internal interoperability within LIS is
achieved by redesigning the LDAS driver to provide flexible and adaptive
interfaces between subsystems, including using advanced features of the
Fortran 90 programming language to simulate object oriented behavior and
thereby provide well-defined interfaces or \"hook points\" for adding
additional land surface models and input data sets. External
interoperability is achieved by adopting the ALMA data exchange
convention and by defining LIS as a fully ESMF-compliant land model
component.

## 4.2 First Code Improvement

The first code improvement milestone for LIS was approved in April,
2003, and included the first application of the global LIS at a 5km
spatial resolution. The milestone was achieved on the NASA Ames SGI
Origin system "Lomax", based on the heavy use of Chapman for the
Columbia accident investigation and the creation of a special queue on
Lomax for the LIS team. The Milestone F results demonstrate significant
improvement in the code relative to the Milestone E baseline, including
parallelization of the previously serial baseline code and P/2 scaling
up to 8 processors, as shown in Figure 1.

![](media/image1.png){width="5.997916666666667in"
height="3.1256944444444446in"}

[]{#__RefHeading___Toc52961070 .anchor}Figure 1. LIS timing results for
Milestone F on Lomax at 5km.

Based on our Milestone E baselining results, the code improvements for
Milestone F concentrated on improving the performance of functions for
spatial and temporal interpolation, as well as the land surface models
themselves. Optimization of these routines, including substantial memory
management, resulted in a factor of 5 speedup in runtime at ¼ degree
spatial resolution for a serial execution, as shown in Table 1.

[]{#__RefHeading___Toc52961077 .anchor}Table 1. Reduction in memory and
execution time on a single processor for LIS relative to LDAS for one
day, 1/4 degree global run with the Noah land surface model.

![](media/image2.wmf){width="5.492361111111111in"
height="1.4916666666666667in"}

## 4.3 Interoperability Prototype

The LIS Interoperability Prototype for Milestone I was submitted to the
CT team on August 15, 2003. Based on feedback received on September 12,
2003, the associated software engineering documents are being revised
for resubmission and approval. The LIS interoperability prototype
demonstrates both internal and external interoperability as defined
above, in addition to portability of the LIS code to the LIS cluster. In
particular, there are three key tests demonstrated by the prototype:

1.  Internal Interoperability Test

> Summary: Demonstrate interoperability of LIS driver by adding the
> third Land Surface Model, VIC. Demonstrate that LIS/VIC combination
> works on SGI 3000.

2.  External Interoperability Test

> Summary: Verify that ALMA mandatory outputs are available from CLM,
> Noah, and VIC in the current LIS driver, including variable names,
> units and sign conventions.

3.  Portability Test

> Summary: Verify that LIS will run on the LIS Cluster at both ¼ degree
> and 5 km resolution. In this test, only the ¼ degree runs were
> successful due to a bug found in the GDS code.

As shown in Figures 2 and 3, the 5km VIC results on the SGI suggest
significant new capabilities from the LIS, particularly in the area of
resolving the effects of urban areas on energy fluxes, commonly known as
the "urban heat island".

![](media/image3.png){width="5.0in" height="3.7625in"}

[]{#__RefHeading___Toc52961071 .anchor}Figure 2. Latent heat flux (Qle)
from the VIC land surface model in LIS v2.0. Spatial resolution is 1/4
degree.

![](media/image4.png){width="5.0in" height="3.7625in"}

[]{#__RefHeading___Toc52961072 .anchor}Figure 3. Same as Figure 2.,
except spatial resolution is 5 km. Note features resolved by the
increased resolution, including urban areas (e.g., Baltimore-Washington,
Atlanta, Houston), as well as the coastlines.

# 5 Status/Plans

In addition to the Technological Accomplishments described above, the
LIS team has made significant progress towards future milestones in the
areas of interfacing with ESMF, user interface development and customer
delivery. Key progress in these areas is described below, followed by a
discussion of plans for FY04.

## 5.1 Interfacing with the developing ESMF

In an effort to ensure that the developing ESMF meets the needs of land
surface modeling, and will provide capabilities that can be successfully
demonstrated in LIS, we have formed several linkages with the ESMF team,
including becoming ESMF "Partners", with access to interim releases of
the ESMF code. In addition, we have attended all ESMF team meetings, and
have fully participated in component reviews, including the most recent
Time Manager Interface Review. Further, Arlindo da Silva continues to be
a member of our review board, and Paul Houser is a member of the ESMF
review board.

The most troubling aspect of the LIS team's dependency on ESMF is the
expectation that the ESMF team's release of an ESMF-compliant version of
CLM will be delayed until at least Spring, 2004, which puts our July
2004 Milestone J in jeopardy. To mitigate this risk, the LIS team
proposes that our interoperability design, which includes the definition
of LIS itself (including CLM, VIC and NOAH) as an ESMF land surface
model component, will meet the spirit of the full interoperability
milestone without relying on the ESMF team's ability to meet their own
demonstration milestone in a timely manner. The LIS team would like to
propose a teleconference to further discuss this issue, and renegotiate
our milestones as appropriate and necessary.

## 5.2 User Interface Development

As described in our Software Design document, and the associated User
Interface Design document, the LIS user interface will provide
functionality for three levels of users, including associated data
access and security requirements. Level 1 users are the general public,
who will access the LIS data through a standard web browser, as shown in
Figure 4. Information provided to this class will only include static
images, animations and text.

![](media/image5.png){width="5.995138888888889in"
height="5.147222222222222in"}

[]{#__RefHeading___Toc52961073 .anchor}Figure 4. The Land Information
System Level 1 User Interface.

Level 2 users will have more direct access to LIS data, and therefore
must register using the links provided in the Level 1 interface shown in
Figure 4. Level 2 users will be allowed to either dynamically generate
an image via a web browser; use a DODS client; or access raw data from
the LIS ftp server.

Level 3 users have the highest access level in addition to all the Level
2 and Level 1 access privileges; they will be able to access the
parallel computing power of LIS system, including an account on the LIS
cluster and a web interface for submitting LIS jobs, as shown in Figure
5. Level 3 users will be the LIS developers and collaborators, and a
select group of users.

![](media/image6.png){width="5.999305555555556in" height="4.69375in"}

[]{#__RefHeading___Toc52961074 .anchor}Figure 5. Prototype LIS level 3
user interface.

## 5.3 Customer Delivery to NOAA/NCEP

Towards our August 2004 customer delivery Milestone K, the LIS team has
initiated an effort to port LIS v2.0 (Milestone I) to NOAA/NCEP for
testing as an operational land data assimilation system. On May 29,
2003, the respective Land Teams of NCEP/EMC (Lead, Dr. Kenneth Mitchell)
and NASA Goddard Hydrological Sciences Branch held a 1-day workshop at
Goddard to begin the process of transferring LIS to the NCEP Central
Computing Facility (NCCF, an IBM-SP2). The purpose is for applications
by the EMC Land Team for initializing the land states of the NCEP/EMC
Global Forecast System (GFS: both weather and seasonal) via various land
data assimilation scenarios.

The two land teams have decided to carry out our first NCEP tests of LIS
using the NCEP Noah land model for the test period of May 2003, on the
GFS T62 Guassian grid, corresponding to the T62 Gaussian grid of EMC\'s
current seasonal forecast model. In these tests LIS will use the same
terrain-height field and land mask as the NCEP T62 global model.
Moreover, these NCEP LIS tests will use exactly the same land surface
characteristics fields (vegetation, soils) and parameters and Noah
version number as NCEP's current tests of the Noah land model in the
GFS. We fully expect that these efforts will contribute to LIS's
portability and customer delivery objectives.

## 5.5 FY04 Plans

As shown above, the key FY04 milestones relate to performance,
interoperability and customer delivery. Towards these milestones, we
will be continuing to re-design and implement parallel I/O, based on the
GDS, and in consultation with the CT staff scientists, in order to
achieve the second code improvement milestone. In addition, we will
fully implement our Level 2 and Level 3 user interfaces, including web
configuration and visualization interfaces, GDS-LDAS interface, and
LDAS-land surface model interfaces. We will also continue the porting
and testing of the LIS code to NCEP for eventual use as an operational
system. Finally, further adoption of the ESMF infrastructure utilities
will continue, based on interim releases, in order to support the
definition of LIS as a fully-compliant land model component.

# 6 Points of Contact

Dr. Paul Houser, Co-PI

Head, Hydrological Sciences Branch

NASA-GSFC Code 974

Greenbelt, Maryland 20771

Office: 301/614-5772 Home: 410/872-0549

Fax: 301/614-5808 Cellular: 301/613-3782

E-mail: houser@hsb.gsfc.nasa.gov

Web: http://hsb.gsfc.nasa.gov

Dr. Christa Peters-Lidard, Co-PI and Project Manager

Research Scientist, Hydrological Sciences Branch

NASA-GSFC Code 974

Greenbelt, Maryland 20771

Office:301/614-5811 Fax:301/614-5808

E-mail: cpeters@hsb.gsfc.nasa.gov

Web: http://hsb.gsfc.nasa.gov/cpeters

# 7 List of Publications

None at this time.

# 8 List of Conference Presentations

Peters-Lidard, C. D., P. R. Houser, M. Rodell, B. Cosgrove, 2003: NASA's
Land Data Assimilation Systems, CNES Workshop on Hydrology from Space,
29 Sep-01 Oct 2003, Toulouse, France.

Peters-Lidard, C. D., S. Kumar, Y. Tian, J. L. Eastman, and P. R.
Houser, 2004: [GLOBAL URBAN-SCALE LAND-ATMOSPHERE MODELING WITH THE LAND
INFORMATION
SYSTEM](http://ams.confex.com/ams/84Annual/PNFUZ/abstracts/73726.htm),
Oral Presentation 4.1 at [Symposium on Planning, Nowcasting, and
Forecasting in the Urban
Zone](http://ams.confex.com/ams/84Annual/PNFUZ/index.html), American
Meteorological Society Annual Meeting, January 2004, Seattle, WA.

# 

# 9 List of Media References

None at this time.

# 10 List of Patents Filed

None at this time.

# 11 List of Students/Post Docs Trained

The LIS project enlisted the help of two undergraduate students this
summer to assist with construction of the cluster. In addition, the
project hired two post-docs through GEST for the duration of the
three-year project (Kumar, Tian), and is also supporting a part-time
GEST associate (Eastman).

## Students Trained

-   Uttam Majumder, SIECA Summer Intern, 2002

-   Nikkia Anderson, Summer Intern, 2002

## Post Docs Trained

-   Sujay Kumar, Ph.D.

-   Yudong Tian, Ph.D.

-   Joseph L. Eastman, Ph.D.

# 12 References

# 

ALMA: <http://www.lmd.jussieu.fr/ALMA/>

Atlas, R. M., and R. Lucchesi, File Specification for GEOS-DAS Gridded
Output. Available online at :
<http://dao.gsfc.nasa.gov/DAO_docs/File_Spec_v4.3.html> , 2000.

Chen, F., K. Mitchell, J. Schaake, Y. Xue, H. Pan, V. Koren, Y. Duan, M.
Ek, and A. Betts, "Modeling of land-surface evaporation by four schemes
and comparison with FIFE observations", *J. Geophys. Res.*, 101, D3,
7251-7268, 1996.

CLM: <http://www.cgd.ucar.edu/tss/clm/>

Collatz G. J., C. Grivet, J. T. Ball, and J. A. Berry, J. A.
"Physiological and Environmental Regulation of Stomatal Conductance:
Photosynthesis and Transpiration: A Model that includes a Laminar
Boundary Layer", *Agric. For. Meteorol.* , 5, pp 107 \-- 136, 1991.

Derber, J. C., D. F. Parrish, and S. J. Lord, "The new global
operational analysis system at the National Meteorological Center",
*Wea. And Forecasting,* 6, pp 538-547, 1991.

ESMF: <http://www.esmf.ucar.edu/>

GrADS-DODS server: <http://grads.iges.org/grads/gds/>

Hamill, T. M., R. P. d'Entremont, and J. T. Bunting, "A description of
the Air Force real-time nephanalysis model", *Wea. Forecasting,* 7, pp
238-306, 1992.

Hofstee, H. P., J. J. Likkien, and J. L. A. Van De Snepscheut \"A
Distributed Implementation of a Task Pool\". *Research Directions in
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Jarvis, P. G., " The interpretation of leaf water potential and stomatal
conductance found in canopies in the field", *Phil. Trans. R. Soc.*
London, Ser. B, 273, pp 593 -- 610, 1976.

Kopp, T. J. and R. B. Kiess, "The Air Force Global Weather Central cloud
analysis model", *AMS 15^th^ Conf. on Weather Analysis and Forecasting,*
Norfolk, VA, pp 220-222, 1996.

LDAS: <http://ldas.gsfc.nasa.gov/>

NOAH: <http://www.emc.ncep.noaa.gov/mmb/gcp/noahlsm/README_2.2.htm>

Pfaendtner, J., S. Bloom, D. Lamich, M. Seablom, M. Sienkiewicz, J.
Stobbie, and A. da Silva, "Documentation of the Goddard Earth Observing
System (GEOS) Data Assimilation System -- Version 1", *NASA Technical
Memorandum* 104606, 4, pp 44, 1995.

Peters-Lidard, C. D., P. R. Houser, M. Rodell, B. Cosgrove, 2003: NASA's
Land Data Assimilation Systems, CNES Workshop on Hydrology from Space,
29 Sep-01 Oct 2003, Toulouse, France.

Peters-Lidard, C. D., S. Kumar, Y. Tian, J. L. Eastman, and P. R.
Houser, 2004: [GLOBAL URBAN-SCALE LAND-ATMOSPHERE MODELING WITH THE LAND
INFORMATION
SYSTEM](http://ams.confex.com/ams/84Annual/PNFUZ/abstracts/73726.htm),
Oral Presentation 4.1 at [Symposium on Planning, Nowcasting, and
Forecasting in the Urban
Zone](http://ams.confex.com/ams/84Annual/PNFUZ/index.html), American
Meteorological Society Annual Meeting, January 2004, Seattle, WA.

Reynolds, C. A., T. J. Jackson, and W. J. Rawls, "Estimating available
water content by linking the FAO Soil Map of the World with global soil
profile databases and pedo-transfer functions" *American Geophysical
Union, Fall Meeting, Eos Trans. AGU*, 80, 1999.

Richards, L. A., "Capillary conduction of liquids in porous media",
*Physics,* 1, pp 318---333, 1931.

Rodell, M., P. R. Houser, U. Jambor, J. Gottschalck, C.-J. Meng, K.
Arsenault, B. Cosgrove, J. Radakovich, M. Bosilovich, J. K. Entin, J. P.
Walker, and K. Mitchell, The Global Land Data Assimilation System. Bull.
Amer. Meteor. Soc., 2003.

Rogers, E., T. L. Black, D. G. Deaven, G. J. DiMego, Q. Zhao, M.
Baldwin, N. W. Junker, and Y. Lin, "Changes to the operational \"early\"
eta analysis / forecast system at the National Centers for Environmental
Prediction" *Wea. Forecasting*, 11, pp 391-413, 1996.

Shapiro, R. "A simple model for the calculation of the flux of direct
and diffuse solar radiation through the atmosphere", AFGL-TR-87-0200,
Air Force Geophysics Lab, Hanscom AFB, MA.

Turk, F. J., G. Rohaly, J. D. Hawkins, E. A. Smith, A. Grose, F. S.
Marzano, A. Mugnai, and V. Levizzani, "Analysis and assimilation of
rainfall from blended SSM/I, TRMM, and geostationary satellite data",
*AMS 10^th^ Conf. On Sat. Meteor. and Ocean.,* Long Beach, CA, 9-14
January, pp 66-69, 2000.

VIC:
<http://www.hydro.washington.edu/Lettenmaier/Models/VIC/VIChome.html>

#