# Presentation: 104346

## Assessment of the NCEP data assimilation systems during the NAME04 EOP period

- Marco Carrera, Kingtse Mo,
-  and Wayne Higgins
- CPC/NCEP/NWS/NOAA

## Objectives

-  a) Inter-compare the NCEP data assimilation systems;
- b) Compare the NCEP assimilation systems with soundings;
- c) During EOP, other  NAME04 data including aircraft P3, ship , radar and PIBAL data did not get into the NCEP system in time, but the soundings did. This gives an unique opportunity to examine the impact of soundings.

## The NCEP data assimilation systems

-    Two Global systems:
- CDAS Climate data assimilation system ( resolution T62L28; approx 250 km)
- GDAS: Global data assimilation system( resolution T254L64; approx 50km)
-     **Two regional systems**
- EDAS: Eta model 3D-Var Data assimilation system (resolution 12kmL64)
- RCDAS: Regional climate data assimilation system
- (resolution 32kmL45)

## Table 1 Input data differences among the NCEP data assimilation systems

|  | GFS | Eta operational | Regional  CDAS | comments |
| --- | --- | --- | --- | --- |
| GMS, METEOSAT,GOES cloud drift IR and visible winds | u, v | u, vT |  u, v |  |
| GOES water vapor cloud top winds | u, v | u, v | not used |  |
| Surface land observations | u, v, T , Ps, q | Ps | Ps 10m winds,2m q |  |
| Surface ship and buoy observations | u, v, T, Ps, q | u, v, T, Ps, q | U ,v T, s and q
From the COADS |  |
| SSM/I wind speeds | Used directly | Assigns direction from guess | Not used |  |
| Quickscat wind speed and direction | Not used | Used | Not used |  |
| SSM/I precipitable water  | Used  | Not used | Not used |  |
| SSM/I precipitation estimates | Not used | Used | Not used | Precipitation included through variational scheme and model physics |
| TRMM TMI precipitation estimates | Not used | Used | Not used | Precipitation included through variational scheme and model physics |
| GOES precipitable water | Used over land  | Not used | Not used |  |
| NOAA-15, NOAA-16 AMSU-A 1b radiances | Used | Used | Not used |  |
| NOAA-15 –16 and –17 AMSU-B 1b radiance s | Used | Used | Not used |  |

## Precipitation assimilation

- GDAS does not assimilate precipitation;
- CDAS2 uses the CMAP pentad  P data to adjust soil moisture, but does not assimilate P directly;
- EDAS assimilates P over land;
- RCDAS assimilates P over land and oceans

## NAME EOP soundings

- P. Penasco 31.18N, 113.33W         Las Vegas     36.62N,116.02W
- Kino Bay 28.8N,111.9W                   San Diego    36.62N,116.02W
- Los Mochis 25.4N, 109.05W             Flagstaff       32.85N,117.12W
- Loreto 26.01N, 111.21W                   Albuquerque 35.05N,106.62W
- Empalme 27.95N,110.77W               El Paso          31.87N,106.7W
- Mazatlan 23.20N,106.42 W               Amarillo         35.23N,101.7W
- Chihuahua 28.63N,106.08W             Midland         31.95N,102.18W
- Torreon      25.53N,103.45W             Del Rio         29.37N, 100.92W
- Monterrey 25.87N,100.23W              Yuma          32.51N,114W
- La Paz       24.17N,110.3W                Phoenix       33.45N,111.95W
- Guadalupe 22.75N, 102.5W              Belize city    17.53N,88.3W
- Tucson    32.12N,110.92W             San Jose (Costa Rica)  10N,84.2W

## Moisture transport from data assimilation systems

- Two regional analyses have the NLDAS component and assimilate P so P, and  E are  similar and should be more reliable;
- The GDAS does not assimilate P so the differences between the GDAS and the gauge P data are larger;
-  All systems show similar low level jet from the Great Plains (GPLLJ), and the easterly zonal  low level jet in the Caribbean (CALLJ).
- The LLJs from the Gulf of California (GCLLJ) from the EDAS and the GDAS are similar, the RCDAS overestimates the strength of the jet.

- ( Summary from the next 4 slides)

- P mean over the EOP:
- During this period, there are positive P anomalies over the central United States and northern Mexico, but drier over southern Mexico

- The EDAS and the RCDAS assimilate P, so P is closer to the observations, both the GDAS and CDAS miss the center of  P maximum over the central US and too much rainfall over southern Mexico

## E

- E-P

- All data assimilation systems show E>P over the central United States.
- Both EDAS and RCDAS have the NLDAS  subsystem so they are similar,  and more reliable,
- while the GDAS
- shows a shifted center of E-P.

## Vertically integrated meridional moisture flux  [qv] ( contoured) and flux( Vector) 

- Vertically integrated meridional moisture flux  [qv] ( contoured) and flux( Vector)

- The GPLLJ from 3 systems are similar;
- The GCLLJ from the GDAS and EDAS are similar , while the RCDAS depicts a very strong jet with a center over the Gulf of California

- Units:kg/(ms)

## Vertically integrated meridional moisture flux and v at 30N

- Both GDAS and EDAS show
- a) similar vertical profiles of the GPLLJ, and GCLLJ.
- b) the GCLLJ is confined in the boundary layer.
-  The RCDAS shows a similar GPLLJ, and a much stronger GCLLJ extending  to 700 hPa

- Units: kg/(ms)

- Units: m/s

## Comparison with soundings & satellite data

- The model generated T, V, U and q outputs are interpolated to the observed sounding sites from 4 nearest grid points;
- Both model and observed soundings are archived at the mandatory levels;
- For  mean vertical profiles, the mean is taken over  the period that the observed soundings are available (9July- 10 August).

- The next 5 slides

## Del Rio (29.37N,100.92W) is located near the Maximum of the GPLLJ.

- The comparison shows :
- Little difference between the RCDAS and EDAS;
- They both underestimate the strength of the (qv).  The RCDAS errors are smaller

- In comparison with the satellite Quickscat surface winds , all systems capture the location of  the easterly LLJ maximum. The magnitude differs less than 2 m/s

- All systems capture the CALLJ and they compare favorably with the satellite estimates.

## Compare v-wind profile with soundings

- ISS & GLASS  Soundings over the NAME Tier I region

- The largest differences along the Gulf of California are located over the northern Gulf, where the large GCLLJ is located. At Puerto Penasco , the RCDAS v-winds are  more than 1 m/s too strong.
- At  Tucson, both RCDAS and EDAS have weaker winds at the lower levels.

- Red RCDAS, Green: EDAS, black (sounding)

- a) Del Rio

- d)Tucson

- Penasco, Kinobay,Loreto & Losmuchis

## Compare T and q with soundings

- Red RCDAS, Green EDAS & dark soundings

- Both T and q from the EDAS and the RCDAS compare favorably with the soundings

## The comparison with the sounding at Empalme is good.

- The differences between the RCDAS and the observations are concentrated over the northern Gulf of California (e.g. near Penasco), where the difference of [qv] flux is

## Comparison with sounding at P. Penasco both the EDAS and the RCDAS over estimate [qv] at lower level, but the differences for the RCDAS are larger.

- The differences between the ECDAS and RCDAS extend to 700 hPa consistent with vertical profile of qv at 30N (slide 10)
- The largest differences are from 1-7July when the sounding was not in operation. This suggests that the soundings have impact on the analyses.
- This point is clear from the next 2 slides

## Difference between RCDAS and EDAS at Penasco site. There are total 29 vertical levels

- Penasco data were available from July 8 to 11August 2004.
- The differences between the two analyses are large when the sounding data were not available.

## Vertically integrated moisture flux [qv] from RCDAS and EDAS for the periods with & without the ISS  & GLASS soundings

- RCDAS

- EDAS

- The GCLLJ from the RCDAS is 200 kg/(ms) strong in comparison with the EDAS without soundings.
- With the ISS soundings, the difference reduces to 50 kg/(ms)
- The period with soundings: July 11-August 11
- Period with no soundings:
- 1-10 July and
- 16-31 August

## Conclusions

-   During the EOP periods, most soundings entered the NCEP buffer files and were accepted by the assimilation systems;
-                  The comparison shows:
- a) the RCDAS overestimates the [qv] from the Gulf of California with a maximum located over the northern Gulf, while the EDAS compares more favorably with soundings;
- b) All systems have similar CALLJ and GPLLJ and compare well with soundings;
- c) The soundings are effective in correcting model biases