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Overview

Authors: 超级管理员 | Edit: xingqiang

Chapter 2 presents the same indicators—RAIN, TEMP, RADPAR,and BIOMSS—used in Chapter 1, and combines them with the agronomic indicators—croppedarable land fraction (CALF) and maximum indicators for each of six MPZs,comparing the indicators to their fourteen- and five-year averages.

Table 2.1. January-April 2015 agroclimaticindicators by Major Production Zone, current value and departure from 14YA

 

 rain

 

 TEMP

 

 RADPAR

 

 

Current (mm)

Departure from 14YA (%)

Current
(°C)

Departure from 14YA (°C)

Current
(MJ/m2)

Departure from 14YA (%)

West Africa

158

-10

29.2

0.7

1251

1

South America

694

3

24.8

1.2

1169

4

North America

372

28

4.0

-0.7

780

-5

South and SE Asia

149

21

24.2

0.5

1143

-2

Western Europe

163

-27

6.4

1.0

590

0

C. Europe and W. Russia

177

4

0.5

1.3

522

-3

Note: Departures are expressed in relative terms (percentage) for all variables, except for temperature, for which absolute departure in degrees Celsius is given. Zero means no change from the average value; relative departures are calculated as(C-R)/R*100, with C=current value and R=reference value, which is the fourteen-yearaverage (14YA) for the same period (January-April) for 2001-14.

Table 2.2. January-April 2015 agronomicindicators by Major Production Zone, current season values and departure from5YA

 

 BIOMSS

 

 cropped arable land fraction

 

 maximum VCI

 

Current

Departure from 5YA (%)

Current
(% of pixels)

Departure from 5YA (%)

Current

West Africa

487

-16

65

-8

0.61

South America

1808

5

89

0

0.86

North America

823

15

55

1

0.72

South and Southeast Asia

516

34

83

3

0.81

Western Europe

674

-13

92

1

0.86

Central Europe and W. Russia

676

12

65

-5

0.64









Note: Departuresare expressed in relative terms (percentage) for all variables. Zero means nochange from the average value; relative departures are calculated as(C-R)/R*100, with C=current value and R=reference value, which is the five-year(5YA) average for the same period (January-April) for 2010-2014.

2.2 West Africa

With some minor variations due to elevation and terrainfeatures, most of the West African MPZ was in the dry season in January andFebruary, when the last 2014 crops were being harvested. In March and April,the southernmost areas, particularly in the center and east, have startedplanting maize and rainfed rice. Figure 2.1 illustrates agroclimatic andagronomic indicators for the MPZ for the reporting period.

Compared with average conditions, for January to April theregion as a whole underwent a rainfall deficit in the order of 10%, accompaniedby slightly positive temperature and radiation departures. Taking into accountthe skewed statistical distribution of rainfall (that is, average rainfalloverestimates amounts actually expected), it is still early to say if theslight deficit is likely to impact crops production, although it is likely tohave delayed planting in some of the northernmost areas (the Sahelian areas) ofthe MPZ, especially in north Ghana (RAIN -8%), Côte d'Ivoire (RAIN -6% and TEMP+1.4°C), Nigeria (RAIN -12%), and the southernmost parts of Mali and BurkinaFaso. In Liberia, which is the only country in the MPZ where rice is a majorstaple next to cassava and yams, a rainfall deficit of 13% was recorded. Theonly country that recorded a marked rainfall excess was Togo (+18%), but thismay have been offset by higher than average temperature (+1.1°C).

The rainfall profiles and clusters show that rainfalldeficits occurred throughout the region in April, with the north and westusually experiencing RAIN departures around -10mm in the north and west. TheApril deficit is more marked (close to -30mm) from northern Côte d'Ivoire toCentral Nigeria, where it follows abundant rainfall (+40 mm) in March. Also inApril, the whole region experienced above average temperatures (TEMP, +1.0°C).

Generally, a somewhat late onset of the season compared with average is confirmed by the maximum VCI, for which low values occur in thenorth of Côte d'Ivoire, in Ghana, Togo, Benin, and across northern-centralNigeria. This is also where low VHI values tend to concentrate. Two additionalcrop-related indicators (fraction of cropped arable land (CALF) and BIOMSS)departures, expressed as the departure from the average of the recent fiveseasons only, confirm a drop in production potential close to or below 20% inthe north of the MPZ, except in the very west where drops and improvementscoexist, resulting in mixed but average conditions. Spatial variations in CALFare somehow difficult to interpret in southern Mali and adjacent Côte d'Ivoire,where the indicator values may result from early planting in March, followingFebruary rains.

Altogether, the indicators in the region are consistent withthe expected seasonal behavior of climate and crops, with a possible falsestart of the cropping season in the northernmost areas in the west and slightdelay of the Sahelian season in the central east, from Burkina Faso to Nigeria.