# Presentation: 858668

## Precipitation Assimilation at ECMWF

**P. Bauer**
**P. Lopez**
**A. Benedetti**
**M. Bonazzola **

## 1D+4D-Variational Analysis using Rainfall Observations

**1D+4D-Variational Analysis using Rainfall Observations**

**4D-Var**

## Forecasted Rainrate from 26-12-2002 at 12 UTC ‘ZOE’

- CONTROL

- 1D/TB

- 1D/RR

- PATER/RR

**+6 H**

**+12 H**

**+24 H**

**+48 H**

## RMS-Error of Tropical Geopotential Height Forecasts, 09/2003

**500 hPa**

**200 hPa**

**1000 hPa**

**850 hPa**

**RMS-Error of Tropical Geopotential Height Forecasts, 09/2003**

## Candidate Problems with 1D+4D-Var Analysis

**Nearest grid-point TB vs. grid-box averaged:**
**± 3h vs ± 30’ time window:**

**± 3h**
**± 30’**

**Candidate Problems with 1D+4D-Var Analysis**

## TCWV FG vs. AN Departure Statistics

**1D-Var: RR****	****	****	****	****1D-Var: TB**

**FG**
**AN**
**RAIN**
**CLEAR**
**	****          ****FG                           AN                                 FG                            AN**

**RAIN**
**CLEAR**

**TCWV FG vs. AN Departure Statistics**

## Observation-Model Bias, SSM/I 19v,h; 22v Channels

**Observation-Model Bias, SSM/I 19v,h; 22v Channels**

## TCWV FG vs. AN Departure Statistics (w/ Bias-correction)

**FG**
**AN**
**RAIN**
**CLEAR**
**	****       ****FG                            AN                                 FG                             AN**

**TCWV FG vs. AN Departure Statistics (w/ Bias-correction)**

**before****	****	****	****	****             after**

## Impact of TB Bias-correction on 4D-Var Analysis

**Impact of TB Bias-correction on 4D-Var Analysis**

**Hurricane Fabian 2003-09-01 1200 UTC**

## RMS-Error of Tropical Geopotential Height Forecasts, 09/2003

**500 hPa**

**200 hPa**

**1000 hPa**

**850 hPa**

**RMS-Error of Tropical Geopotential Height Forecasts, 09/2003**

## ‘Isabel’ Track Forecast from 1D+4D-Var Analyses (cycling)

**Analysis: 2003091212**

**Analysis: 2003091512**

**Analysis: 2003091612**

**‘****Isabel’ Track Forecast from 1D+4D-Var Analyses (cycling)**

**	****   ****control**
**      ****	****           ****rain**
**	****        ****assimilation**
**observed**

## Plans for 2004+

**Technical Issues:**
** ****Perform 1D-Var with physics package for access to all physical variables in ****  observation operator at full spatial/temporal resolution (40 km/30’ ******** 25 km/30’).**
** ****Test 1D+4D-Var (w/ bias-correction) using global SSM/I+SSMIS data (22 GHz+).**
** ****Investigate performance (observation errors, new J****b****-formulation) using ****  dynamics/precipitation scores, track forecasts, PR data, model spin-down.**
** ****Activate with December 2004 model cycle.**
**Science Issues:**
** ****Improve on bias-correction (physics, RT) for better trade-off between information ****  and bias.**
** ****Investigate direct 4D-Var TB-assimilation for stronger impact on dynamics.**
** ****Add more complementary channels (e.g. SSMIS 22+183 GHz channels, possibly ****  T-sounding channels) for more consistent cloud-precipitation analysis.**

**Global data assimilation systems provide excellent tool for GPM data monitoring:**
**Individual data quality/consistency is monitored by model fit to all other observations related to atmospheric dynamics, moisture, temperature and surface state.**